MONSTER IN THE DARK: THE ULTRALUMINOUS GRB 080607 AND ITS DUSTY ENVIRONMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perley, D. A.; Morgan, A. N.; Miller, A. A.

2011-02-15

We present early-time optical through infrared photometry of the bright Swift gamma-ray burst (GRB) 080607, starting only 6 s following the initial trigger in the rest frame. Complemented by our previously published spectroscopy, this high-quality photometric data set allows us to solve for the extinction properties of the redshift 3.036 sightline, giving perhaps the most detailed information to date on the ultraviolet continuum absorption properties of any sightline outside our Local Group. The extinction properties are not adequately modeled by any ordinary extinction template (including the average Milky Way, Large Magellanic Cloud, and Small Magellanic Cloud curves), partially because themore » 2175 A feature (while present) is weaker by about a factor of two than when seen under similar circumstances locally. However, the spectral energy distribution is exquisitely fitted by the more general Fitzpatrick and Massa parameterization of Local-Group extinction, putting it in the same family as some peculiar Milky Way extinction curves. After correcting for this (considerable, A{sub V} = 3.3 {+-} 0.4 mag) extinction, GRB 080607 is revealed to have been among the most optically luminous events ever observed, comparable to the naked-eye burst GRB 080319B. Its early peak time (t{sub rest} < 6 s) indicates a high initial Lorentz factor ({Gamma}>600), while the extreme luminosity may be explained in part by a large circumburst density. Only because of its early high luminosity could the afterglow of GRB 080607 be studied in such detail in spite of the large attenuation and great distance, making this burst an excellent prototype for the understanding of other highly obscured extragalactic objects, and of the class of 'dark' GRBs in particular.« less

The Supercritical Pile GRB Model: The Prompt to Afterglow Evolution

NASA Technical Reports Server (NTRS)

Kazanas, Demosthenes

2008-01-01

The 'Supercritical Pile' is a very economical gamma ray burst (GRB) model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at an energy sim 1 MeV. We extend this model to include also the evolution of the RBW Lorentz factor Gamma and thus follow the spectral and temporal features of this model into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model can be the sources of rich time evolution which we have begun to explore. In particular, one can this way obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the nu F spectra. Furthermore, the existence of a kinematic threshold in this model provides for a operational distinction of the prompt and afterglow GRB stages; in fact, the afterglow stage sets in when the RBW Lorentz factor cannot anymore fulfill the kinematic condition for pair formation in the photon - proton pair production reactions that constitute the fundamental process for the dissipation of the blast wave kinetic energy. We present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

Detection prospects for GeV neutrinos from collisionally heated gamma-ray bursts with IceCube/DeepCore.

PubMed

Bartos, I; Beloborodov, A M; Hurley, K; Márka, S

2013-06-14

Jet reheating via nuclear collisions has recently been proposed as the main mechanism for gamma-ray burst (GRB) emission. In addition to producing the observed gamma rays, collisional heating must generate 10-100 GeV neutrinos, implying a close relation between the neutrino and gamma-ray luminosities. We exploit this theoretical relation to make predictions for possible GRB detections by IceCube + DeepCore. To estimate the expected neutrino signal, we use the largest sample of bursts observed by the Burst and Transient Source Experiment in 1991-2000. GRB neutrinos could have been detected if IceCube + DeepCore operated at that time. Detection of 10-100 GeV neutrinos would have significant implications, shedding light on the composition of GRB jets and their Lorentz factors. This could be an important target in designing future upgrades of the IceCube + DeepCore observatory.

Search for High-Energy Muon Neutrinos from the "Naked-Eye" GRB 080319B with the IceCube Neutrino Telescope

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Bolmont, J.; Botner, O.; Bradley, L.; Braun, J.; Breder, D.; Castermans, T.; Chirkin, D.; Christy, B.; Clem, J.; Cohen, S.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Day, C. T.; De Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Diaz-Velez, J. C.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Edwards, W. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Ganugapati, R.; Gerhardt, L.; Gladstone, L.; Goldschmidt, A.; Goodman, J. A.; Gozzini, R.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gunasingha, R. M.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Hasegawa, Y.; Heise, J.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Imlay, R. L.; Inaba, M.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Knops, S.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Lauer, R.; Lennarz, D.; Lucke, A.; Lundberg, J.; Lünemann, J.; Madsen, J.; Majumdar, P.; Maruyama, R.; Mase, K.; Matis, H. S.; McParland, C. P.; Meagher, K.; Merck, M.; Mészáros, P.; Middell, E.; Milke, N.; Miyamoto, H.; Mohr, A.; Montaruli, T.; Morse, R.; Movit, S. M.; Münich, K.; Nahnhauer, R.; Nam, J. W.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; Ono, M.; Panknin, S.; Patton, S.; Pérez de los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Pohl, A. C.; Porrata, R.; Potthoff, N.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Rutledge, D.; Ryckbosch, D.; Sander, H.-G.; Sarkar, S.; Schlenstedt, S.; Schmidt, T.; Schneider, D.; Schukraft, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoufer, M. C.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sulanke, K.-H.; Sullivan, G. W.; Swillens, Q.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Terranova, C.; Tilav, S.; Toale, P. A.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; Van Overloop, A.; Voigt, B.; Walck, C.; Waldenmaier, T.; Walter, M.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebusch, C. H.; Wiedemann, A.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Woschnagg, K.; Xu, X. W.; Yodh, G.; Yoshida, S.; IceCube Collaboration

2009-08-01

We report on a search with the IceCube detector for high-energy muon neutrinos from GRB 080319B, one of the brightest gamma-ray bursts (GRBs) ever observed. The fireball model predicts that a mean of 0.1 events should be detected by IceCube for a bulk Lorentz boost of the jet of 300. In both the direct on-time window of 66 s and an extended window of about 300 s around the GRB, no excess was found above background. The 90% CL upper limit on the number of track-like events from the GRB is 2.7, corresponding to a muon neutrino fluence limit of 9.5 × 10-3 erg cm-2 in the energy range between 120 TeV and 2.2 PeV, which contains 90% of the expected events.

Fermi observations of high-energy gamma-ray emission from GRB 080916C.

PubMed

Abdo, A A; Ackermann, M; Arimoto, M; Asano, K; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Band, D L; Barbiellini, G; Baring, M G; Bastieri, D; Battelino, M; Baughman, B M; Bechtol, K; Bellardi, F; Bellazzini, R; Berenji, B; Bhat, P N; Bissaldi, E; Blandford, R D; Bloom, E D; Bogaert, G; Bogart, J R; Bonamente, E; Bonnell, J; Borgland, A W; Bouvier, A; Bregeon, J; Brez, A; Briggs, M S; Brigida, M; Bruel, P; Burnett, T H; Burrows, D; Busetto, G; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Ceccanti, M; Cecchi, C; Celotti, A; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Cominsky, L R; Connaughton, V; Conrad, J; Costamante, L; Cutini, S; Deklotz, M; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Dingus, B L; do Couto E Silva, E; Drell, P S; Dubois, R; Dumora, D; Edmonds, Y; Evans, P A; Fabiani, D; Farnier, C; Favuzzi, C; Finke, J; Fishman, G; Focke, W B; Frailis, M; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Giebels, B; Giglietto, N; Giommi, P; Giordano, F; Glanzman, T; Godfrey, G; Goldstein, A; Granot, J; Greiner, J; Grenier, I A; Grondin, M-H; Grove, J E; Guillemot, L; Guiriec, S; Haller, G; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hernando Morat, J A; Hoover, A; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kavelaars, A; Kawai, N; Kelly, H; Kennea, J; Kerr, M; Kippen, R M; Knödlseder, J; Kocevski, D; Kocian, M L; Komin, N; Kouveliotou, C; Kuehn, F; Kuss, M; Lande, J; Landriu, D; Larsson, S; Latronico, L; Lavalley, C; Lee, B; Lee, S-H; Lemoine-Goumard, M; Lichti, G G; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Marangelli, B; Mazziotta, M N; McBreen, S; McEnery, J E; McGlynn, S; Meegan, C; Mészáros, P; Meurer, C; Michelson, P F; Minuti, M; Mirizzi, N; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Moretti, E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Nelson, D; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paciesas, W S; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Perri, M; Pesce-Rollins, M; Petrosian, V; Pinchera, M; Piron, F; Porter, T A; Preece, R; Rainò, S; Ramirez-Ruiz, E; Rando, R; Rapposelli, E; Razzano, M; Razzaque, S; Rea, N; Reimer, A; Reimer, O; Reposeur, T; Reyes, L C; Ritz, S; Rochester, L S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Segal, K N; Sgrò, C; Shimokawabe, T; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stamatikos, M; Starck, J-L; Stecker, F W; Steinle, H; Stephens, T E; Strickman, M S; Suson, D J; Tagliaferri, G; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Tenze, A; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Turri, M; Tuvi, S; Usher, T L; van der Horst, A J; Vigiani, L; Vilchez, N; Vitale, V; von Kienlin, A; Waite, A P; Williams, D A; Wilson-Hodge, C; Winer, B L; Wood, K S; Wu, X F; Yamazaki, R; Ylinen, T; Ziegler, M

2009-03-27

Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. The known distance of the burst enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.

The Swift/Fermi GRB 080928 from 1 eV to 150 keV

NASA Technical Reports Server (NTRS)

Sonbas, Eda; Rossi, A.; Schulze, S.; Klose, S.; Kann, D. A.; Ferrero, P.; NicuesaGuelbenzu, A.; Rau, A.; Kruehler, T.; Greiner, J.;

GRB 060605: multi-wavelength analysis of the first GRB observed using integral field spectroscopy

NASA Astrophysics Data System (ADS)

Ferrero, P.; Klose, S.; Kann, D. A.; Savaglio, S.; Schulze, S.; Palazzi, E.; Maiorano, E.; Böhm, P.; Grupe, D.; Oates, S. R.; Sánchez, S. F.; Amati, L.; Greiner, J.; Hjorth, J.; Malesani, D.; Barthelmy, S. D.; Gorosabel, J.; Masetti, N.; Roth, M. M.

2009-04-01

The long and relatively faint gamma-ray burst GRB 060605 detected by Swift/BAT lasted about 20 s. Its afterglow could be observed with Swift/XRT for nearly 1 day, while Swift/UVOT could detect the afterglow during the first 6 h after the event. Here, we report on integral field spectroscopy of its afterglow performed with PMAS/PPak mounted at the Calar Alto 3.5 m telescope. In addition, we report on a detailed analysis of XRT and UVOT data and on the results of deep late-time VLT observations that reveal the GRB host galaxy. We find that the burst occurred at a redshift of z = 3.773, possibly associated with a faint, RC = 26.4 ± 0.3 host. Based on the optical and X-ray data, we deduce information on the SED of the afterglow, the position of the cooling frequency in the SED, the nature of the circumburst environment, its collimation factor, and its energetics. We find that the GRB fireball was expanding into a constant-density medium and that the explosion was collimated with a narrow half-opening angle of about 2.4 degrees. The initial Lorentz factor of the fireball was about 250; however, its beaming-corrected energy release in the gamma-ray band was comparably low. The optical, X-ray afterglow, on the other hand, was rather luminous. Finally, we find that the data are consistent within the error bars with an achromatic evolution of the afterglow during the suspected jet break time at about 0.27 days after the burst. Based on observations collected at the German-Spanish Calar Alto Observatory in Spain (Programme F06-3.5-055) and at the European Southern Observatory, La Silla and Paranal, Chile (ESO Programme 177.D-0591).

Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C

DOE PAGES

Abdo, A. A.; Ackermann, M.; Arimoto, M.; ...

2009-02-19

Gamma-ray bursts (GRBs) are highly energetic explosions signaling the death of massive stars in distant galaxies. The Gamma-ray Burst Monitor and Large Area Telescope onboard the Fermi Observatory together record GRBs over a broad energy range spanning about 7 decades of gammaray energy. In September 2008, Fermi observed the exceptionally luminous GRB 080916C, with the largest apparent energy release yet measured. The high-energy gamma rays are observed to start later and persist longer than the lower energy photons. A simple spectral form fits the entire GRB spectrum, providing strong constraints on emission models. Finally, the known distance of the burstmore » enables placing lower limits on the bulk Lorentz factor of the outflow and on the quantum gravity mass.« less

Time evolution of the spectral break in the high-energy extra component of GRB 090926A

NASA Astrophysics Data System (ADS)

Yassine, M.; Piron, F.; Mochkovitch, R.; Daigne, F.

2017-10-01

Aims: The prompt light curve of the long GRB 090926A reveals a short pulse 10 s after the beginning of the burst emission, which has been observed by the Fermi observatory from the keV to the GeV energy domain. During this bright spike, the high-energy emission from GRB 090926A underwent a sudden hardening above 10 MeV in the form of an additional power-law component exhibiting a spectral attenuation at a few hundreds of MeV. This high-energy break has been previously interpreted in terms of gamma-ray opacity to pair creation and has been used to estimate the bulk Lorentz factor of the outflow. In this article, we report on a new time-resolved analysis of the GRB 090926A broadband spectrum during its prompt phase and on its interpretation in the framework of prompt emission models. Methods: We characterized the emission from GRB 090926A at the highest energies with Pass 8 data from the Fermi Large Area Telescope (LAT), which offer a greater sensitivity than any data set used in previous studies of this burst, particularly in the 30-100 MeV energy band. Then, we combined the LAT data with the Fermi Gamma-ray Burst Monitor (GBM) in joint spectral fits to characterize the time evolution of the broadband spectrum from keV to GeV energies. We paid careful attention to the systematic effects that arise from the uncertainties on the LAT response. Finally, we performed a temporal analysis of the light curves and we computed the variability timescales from keV to GeV energies during and after the bright spike. Results: Our analysis confirms and better constrains the spectral break, which has been previously reported during the bright spike. Furthermore, it reveals that the spectral attenuation persists at later times with an increase of the break characteristic energy up to the GeV domain until the end of the prompt phase. We discuss these results in terms of keV-MeV synchroton radiation of electrons accelerated during the dissipation of the jet energy and inverse Compton emission at higher energies. We interpret the high-energy spectral break as caused by photon opacity to pair creation. Requiring that all emissions are produced above the photosphere of GRB 090926A, we compute the bulk Lorentz factor of the outflow, Γ. The latter decreases from 230 during the spike to 100 at the end of the prompt emission. Assuming, instead, that the spectral break reflects the natural curvature of the inverse Compton spectrum, lower limits corresponding to larger values of Γ are also derived. Combined with the extreme temporal variability of GRB 090926A, these Lorentz factors lead to emission radii R 1014 cm, which are consistent with an internal origin of both the keV-MeV and GeV prompt emissions.

Modeling the Multiband Afterglows of GRB 060614 and GRB 060908: Further Evidence for a Double Power-law Hard Electron Energy Spectrum

NASA Astrophysics Data System (ADS)

Zhang, Q.; Xiong, S. L.; Song, L. M.

2018-04-01

Electrons accelerated in relativistic collisionless shocks are usually assumed to follow a power-law energy distribution with an index of p. Observationally, although most gamma-ray bursts (GRBs) have afterglows that are consistent with p > 2, there are still a few GRBs suggestive of a hard (p < 2) electron energy spectrum. Our previous work showed that GRB 091127 gave strong evidence for a double power-law hard electron energy (DPLH) spectrum with 1 < p 1 < 2, p 2 > 2 and an “injection break” assumed as γ b ∝ γ q in the highly relativistic regime, where γ is the bulk Lorentz factor of the jet. In this paper, we show that GRB 060614 and GRB 060908 provide further evidence for such a DPLH spectrum. We interpret the multiband afterglow of GRB 060614 with the DPLH model in a homogeneous interstellar medium by taking into account a continuous energy injection process, while, for GRB 060908, a wind-like circumburst density profile is used. The two bursts, along with GRB 091127, suggest a similar behavior in the evolution of the injection break, with q ∼ 0.5. Whether this represents a universal law of the injection break remains uncertain and more afterglow observations such as these are needed to test this conjecture.

Prompt emission from the counter jet of a short gamma-ray burst

NASA Astrophysics Data System (ADS)

Yamazaki, Ryo; Ioka, Kunihito; Nakamura, Takashi

2018-03-01

The counter jet of a short gamma-ray burst (sGRB) has not yet been observed, while recent discoveries of gravitational waves (GWs) from a binary neutron star merger GW170817 and the associated sGRB 170817A have demonstrated that off-axis sGRB jets are detectable. We calculate the prompt emission from the counter jet of an sGRB and show that it is typically 23-26 mag in the optical-infrared band 10-10^3 s after the GWs for an sGRB 170817A-like event, which is brighter than the early macronova (or kilonova) emission and detectable by LSST in the near future. We also propose a new method to constrain the unknown jet properties, such as the Lorentz factor, opening angle, emission radii, and jet launch time, by observing both the forward and counter jets. To scrutinize the counter jets, space GW detectors like DECIGO are powerful in forecasting the merger time (≲ 1 s) and position (≲ 1 arcmin) (˜ a week) before the merger.

A limit on the variation of the speed of light arising from quantum gravity effects

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2009-10-28

A cornerstone of Einstein's special relativity is Lorentz invariance—the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l Planck ≈ 1.62 x 10 -33 cm or E Planck = M Planckc 2 ≈ 1.22 x 10 19 GeV), at which quantum effects are expected to strongly affect the nature of space–time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale.more » A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in γ-ray burst (GRB) light-curves. In this paper, we report the detection of emission up to ~31 GeV from the distant and short GRB 090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E Planck on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l Planck/1.2 on the length scale of the effect). Finally, our results disfavour quantum-gravity theories in which the quantum nature of space–time on a very small scale linearly alters the speed of light.« less

A limit on the variation of the speed of light arising from quantum gravity effects.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Asano, K; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Baring, M G; Bastieri, D; Bechtol, K; Bellazzini, R; Berenji, B; Bhat, P N; Bissaldi, E; Bloom, E D; Bonamente, E; Bonnell, J; Borgland, A W; Bouvier, A; Bregeon, J; Brez, A; Briggs, M S; Brigida, M; Bruel, P; Burgess, J M; Burnett, T H; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cecchi, C; Celik, O; Chaplin, V; Charles, E; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Cominsky, L R; Connaughton, V; Conrad, J; Cutini, S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; Dingus, B L; do Couto E Silva, E; Drell, P S; Dubois, R; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Finke, J; Fishman, G; Focke, W B; Foschini, L; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Germani, S; Gibby, L; Giebels, B; Giglietto, N; Giordano, F; Glanzman, T; Godfrey, G; Granot, J; Greiner, J; Grenier, I A; Grondin, M-H; Grove, J E; Grupe, D; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hoversten, E A; Hughes, R E; Jóhannesson, G; Johnson, A S; Johnson, R P; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Kippen, R M; Knödlseder, J; Kocevski, D; Kouveliotou, C; Kuehn, F; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McBreen, S; McEnery, J E; McGlynn, S; Mészáros, P; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Moretti, E; Morselli, A; Moskalenko, I V; Murgia, S; Nakamori, T; Nolan, P L; Norris, J P; Nuss, E; Ohno, M; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Ozaki, M; Paciesas, W S; Paneque, D; Panetta, J H; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Petrosian, V; Piron, F; Porter, T A; Preece, R; Rainò, S; Ramirez-Ruiz, E; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rochester, L S; Rodriguez, A Y; Roth, M; Ryde, F; Sadrozinski, H F-W; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Schalk, T L; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Stamatikos, M; Stecker, F W; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Toma, K; Torres, D F; Tosti, G; Troja, E; Uchiyama, Y; Uehara, T; Usher, T L; van der Horst, A J; Vasileiou, V; Vilchez, N; Vitale, V; von Kienlin, A; Waite, A P; Wang, P; Wilson-Hodge, C; Winer, B L; Wood, K S; Wu, X F; Yamazaki, R; Ylinen, T; Ziegler, M

2009-11-19

A cornerstone of Einstein's special relativity is Lorentz invariance-the postulate that all observers measure exactly the same speed of light in vacuum, independent of photon-energy. While special relativity assumes that there is no fundamental length-scale associated with such invariance, there is a fundamental scale (the Planck scale, l(Planck) approximately 1.62 x 10(-33) cm or E(Planck) = M(Planck)c(2) approximately 1.22 x 10(19) GeV), at which quantum effects are expected to strongly affect the nature of space-time. There is great interest in the (not yet validated) idea that Lorentz invariance might break near the Planck scale. A key test of such violation of Lorentz invariance is a possible variation of photon speed with energy. Even a tiny variation in photon speed, when accumulated over cosmological light-travel times, may be revealed by observing sharp features in gamma-ray burst (GRB) light-curves. Here we report the detection of emission up to approximately 31 GeV from the distant and short GRB 090510. We find no evidence for the violation of Lorentz invariance, and place a lower limit of 1.2E(Planck) on the scale of a linear energy dependence (or an inverse wavelength dependence), subject to reasonable assumptions about the emission (equivalently we have an upper limit of l(Planck)/1.2 on the length scale of the effect). Our results disfavour quantum-gravity theories in which the quantum nature of space-time on a very small scale linearly alters the speed of light.

Search for high-energy neutrinos from bright GRBs with ANTARES

NASA Astrophysics Data System (ADS)

Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Ardid, M.; Aubert, J.-J.; Avgitas, T.; Baret, B.; Barrios-Martí, J.; Basa, S.; Bertin, V.; Biagi, S.; Bormuth, R.; Bourret, S.; Bouwhuis, M. C.; Bruijn, R.; Brunner, J.; Busto, J.; Capone, A.; Caramete, L.; Carr, J.; Celli, S.; Chiarusi, T.; Circella, M.; Coelho, J. A. B.; Coleiro, A.; Coniglione, R.; Costantini, H.; Coyle, P.; Creusot, A.; Deschamps, A.; De Bonis, G.; Distefano, C.; di Palma, I.; Donzaud, C.; Dornic, D.; Drouhin, D.; Eberl, T.; El Bojaddaini, I.; Elsässer, D.; Enzenhöfer, A.; Felis, I.; Fusco, L. A.; Galatà, S.; Gay, P.; Geißelsöder, S.; Geyer, K.; Giordano, V.; Gleixner, A.; Glotin, H.; Gregoire, T.; Gracia-Ruiz, R.; Graf, K.; Hallmann, S.; van Haren, H.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Hößl, J.; Hofestädt, J.; Hugon, C.; Illuminati, G.; James, C. W.; de Jong, M.; Jongen, M.; Kadler, M.; Kalekin, O.; Katz, U.; Kießling, D.; Kouchner, A.; Kreter, M.; Kreykenbohm, I.; Kulikovskiy, V.; Lachaud, C.; Lahmann, R.; Lefèvre, D.; Leonora, E.; Lotze, M.; Loucatos, S.; Marcelin, M.; Margiotta, A.; Marinelli, A.; Martínez-Mora, J. A.; Mathieu, A.; Mele, R.; Melis, K.; Michael, T.; Migliozzi, P.; Moussa, A.; Mueller, C.; Nezri, E.; Păvălaş, G. E.; Pellegrino, C.; Perrina, C.; Piattelli, P.; Popa, V.; Pradier, T.; Quinn, L.; Racca, C.; Riccobene, G.; Roensch, K.; Sánchez-Losa, A.; Saldaña, M.; Salvadori, I.; Samtleben, D. F. E.; Sanguineti, M.; Sapienza, P.; Schnabel, J.; Schüssler, F.; Seitz, T.; Sieger, C.; Spurio, M.; Stolarczyk, Th.; Taiuti, M.; Tayalati, Y.; Trovato, A.; Tselengidou, M.; Turpin, D.; Tönnis, C.; Vallage, B.; Vallée, C.; Van Elewyck, V.; Vivolo, D.; Vizzocca, A.; Wagner, S.; Wilms, J.; Zornoza, J. D.; Zúñiga, J.

2017-07-01

Gamma-ray bursts are thought to be sites of hadronic acceleration, thus neutrinos are expected from the decay of charged particles, produced in pγ interactions. The methods and results of a search for muon neutrinos in the data of the ANTARES neutrino telescope from four bright GRBs (GRB 080916C, GRB 110918A, GRB 130427A and GRB 130505A) observed between 2008 and 2013 are presented. Two scenarios of the fireball model have been investigated: the internal shock scenario, leading to the production of neutrinos with energies mainly above 100 TeV, and the photospheric scenario, characterized by a low-energy component in neutrino spectra due to the assumption of neutrino production closer to the central engine. Since no neutrino events have been detected in temporal and spatial coincidence with these bursts, upper limits at 90 per cent confidence level on the expected neutrino fluxes are derived. The non-detection allows for directly constraining the bulk Lorentz factor of the jet Γ and the baryon loading fp.

Early X-Ray Flares in GRBs

NASA Astrophysics Data System (ADS)

Ruffini, R.; Wang, Y.; Aimuratov, Y.; Barres de Almeida, U.; Becerra, L.; Bianco, C. L.; Chen, Y. C.; Karlica, M.; Kovacevic, M.; Li, L.; Melon Fuksman, J. D.; Moradi, R.; Muccino, M.; Penacchioni, A. V.; Pisani, G. B.; Primorac, D.; Rueda, J. A.; Shakeri, S.; Vereshchagin, G. V.; Xue, S.-S.

2018-01-01

We analyze the early X-ray flares in the GRB “flare–plateau–afterglow” (FPA) phase observed by Swift-XRT. The FPA occurs only in one of the seven GRB subclasses: the binary-driven hypernovae (BdHNe). This subclass consists of long GRBs with a carbon–oxygen core and a neutron star (NS) binary companion as progenitors. The hypercritical accretion of the supernova (SN) ejecta onto the NS can lead to the gravitational collapse of the NS into a black hole. Consequently, one can observe a GRB emission with isotropic energy {E}{iso}≳ {10}52 erg, as well as the associated GeV emission and the FPA phase. Previous work had shown that gamma-ray spikes in the prompt emission occur at ∼ {10}15{--}{10}17 cm with Lorentz Gamma factors {{Γ }}∼ {10}2{--}{10}3. Using a novel data analysis, we show that the time of occurrence, duration, luminosity, and total energy of the X-ray flares correlate with E iso. A crucial feature is the observation of thermal emission in the X-ray flares that we show occurs at radii ∼1012 cm with {{Γ }}≲ 4. These model-independent observations cannot be explained by the “fireball” model, which postulates synchrotron and inverse-Compton radiation from a single ultrarelativistic jetted emission extending from the prompt to the late afterglow and GeV emission phases. We show that in BdHNe a collision between the GRB and the SN ejecta occurs at ≃1010 cm, reaching transparency at ∼1012 cm with {{Γ }}≲ 4. The agreement between the thermal emission observations and these theoretically derived values validates our model and opens the possibility of testing each BdHN episode with the corresponding Lorentz Gamma factor.

GRB 170817A as a jet counterpart to gravitational wave trigger GW 170817

NASA Astrophysics Data System (ADS)

Lamb, Gavin P.; Kobayashi, Shiho

2018-05-01

Fermi/GBM (Gamma-ray Burst Monitor) and INTEGRAL (the International Gamma-ray Astrophysics Laboratory) reported the detection of the γ-ray counterpart, GRB 170817A, to the LIGO (Light Interferometer Gravitational-wave Observatory)/Virgo gravitational wave detected binary neutron star merger, GW 170817. GRB 170817A is likely to have an internal jet or another origin such as cocoon emission, shock-breakout, or a flare from a viscous disc. In this paper we assume that the γ-ray emission is caused by energy dissipation within a relativistic jet and we model the afterglow synchrotron emission from a reverse- and forward-shock in the outflow. We show the afterglow for a low-luminosity γ-ray burst (GRB) jet with a high Lorentz-factor (Γ); a low-Γ and low-kinetic energy jet; a low-Γ, high kinetic energy jet; structured jets viewed at an inclination within the jet-half-opening angle; and an off-axis `typical' GRB jet. All jet models will produce observable afterglows on various timescales. The late-time afterglow from 10-110 days can be fit by a Gaussian structured jet viewed at a moderate inclination, however the GRB is not directly reproduced by this model. These jet afterglow models can be used for future GW detected NS merger counterparts with a jet afterglow origin.

A New Limit on Planck Scale Lorentz Violation from Gamma-ray Burst Polarization

NASA Technical Reports Server (NTRS)

Stecker, Floyd W.

2011-01-01

Constraints on possible Lorentz invariance violation (UV) to first order in E/M(sub Plank) for photons in the framework of effective field theory (EFT) are discussed, taking cosmological factors into account. Then. using the reported detection of polarized soft gamma-ray emission from the gamma-ray burst GRB041219a that is indicative' of an absence of vacuum birefringence, together with a very recent improved method for estimating the redshift of the burst, we derive constraints on the dimension 5 Lorentz violating modification to the Lagrangian of an effective local QFT for QED. Our new constraints are more than five orders of magnitude better than recent constraints from observations of the Crab Nebula.. We obtain the upper limit on the Lorentz violating dimension 5 EFT parameter absolute value of zeta of 2.4 x 10(exp -15), corresponding to a constraint on the dimension 5 standard model extension parameter. Kappa (sup 5) (sub (v)oo) much less than 4.2 X 10(exp -3)4 / GeV.

GRB 110731A within the IGC paradigm

NASA Astrophysics Data System (ADS)

Primorac, Daria; Ruffini, Remo; Pisani, Giovanni Battista; Aimuratov, Yerlan; Biancol, Carlo Luciano; Karlica, Mile; Melon Fuksman, Julio David; Moradi, Rahim; Muccino, Marco; Penacchioni, Ana Virginia; Rueda, Jorge Armando; Wang, Yu

2018-01-01

Bright gamma-ray burst (GRB) 110731A was simultaneously observed by Fermi and Swift observatories, with a follow up optical observation which inferred the redshift of z = 2.83. Thus, available data are spanning from optical to high energy (GeV) emission. We analyze these data within the induced gravitational collapse (IGC) paradigm, recently introduced to explain temporal coincidence of some long GRBs with type Ic supernovae. The case of binary-driven hypcrnova (BdHN) assumes a close system, which starts as an evolved core - neutron star binary. After the core-collapse event, the new NS - black hole system is formed, emitting the GRB in the process. We performed the time-resolved and time-integrated analysis of the Fermi data. Preliminary results gave isotropic energy Eiso = 6.05 × 1053 erg and the total P-GRB energy of Ep-GRB = 3.7 × 1052 erg. At transparency point we found a Lorentz factor Γ 2.17 × 103 laboratory radius of 8.33 x 1013 cm, P-GRB observed temperature of 168 keV and a baryon load B = 4.35 × 10-4. Simulated light-curve and prompt emission spectra showed the average circum burst medium density to be n 0.03 particles per cm3. We reproduced the X-ray light-curve within the rest-frame of the source, finding the common late power-law behavior, with α = -1.22. Considering these results, we interpret GRB 110731A as a member of a BdHNe group.

Constraining Gamma-ray Burst Initial Lorentz Factor with the Afterglow Onset Feature and Discovery of a Tight Γ0-E γ,iso Correlation

NASA Astrophysics Data System (ADS)

Liang, En-Wei; Yi, Shuang-Xi; Zhang, Jin; Lü, Hou-Jun; Zhang, Bin-Bin; Zhang, Bing

2010-12-01

The onset of gamma-ray burst (GRB) afterglow is characterized by a smooth bump in the early afterglow light curve as the GRB fireball is decelerated by the circumburst medium. We extensively search for GRBs with such an onset feature in their optical and X-ray light curves from the literature and from the catalog established with the Swift/XRT. Twenty optically selected GRBs and 12 X-ray-selected GRBs are obtained, among which 17 optically selected and 2 X-ray-selected GRBs have redshift measurements. We fit these light curves with a smooth broken power law and measure the width (w), rising timescale (t r), and decaying timescale (t d) at full width at half-maximum. Strong mutual correlations among these timescales and with the peak time (t p) are found. The ratio t r/t d is almost universal among bursts, but the ratio t r/t p varies from 0.3 to ~1. The optical peak luminosity in the R band (L R,p) is anti-correlated with t p and w in the burst frame, indicating a dimmer and broader bump peaking at a later time. The isotropic prompt gamma-ray energy (E γ,iso) is also tightly correlated with L R,p and t p in the burst frame. Assuming that the bumps signal the deceleration of the GRB fireballs in a constant density medium, we calculate the initial Lorentz factor (Γ0) and the deceleration radius (R d) of the GRBs with redshift measurements. The derived Γ0 is typically a few hundreds, and the deceleration radius is R dec ~ 2 × 1017 cm. More intriguingly, a tight correlation between Γ0 and E γ,iso is found, namely Γ0 ~= 182(E γ,iso/1052 erg)0.25. This correlation also applies to the small sample of GRBs which show the signature of the afterglow onset in their X-ray afterglow, and to two bursts (GRBs 990123 and 080319B) whose early optical emission is dominated by a reverse shock. The lower limits of Γ0 derived from a sample of optical afterglow light curves showing a decaying feature from the beginning of the observation are also generally consistent with such a correlation. The tight lower limits of Γ0 of GRBs 080916C and 090902B derived from the opacity constraints with Fermi/LAT observations are also consistent with the correlation at the 2σ confidence level, but the short GRB 090510 is a clear outlier of this relation. This correlation may give insight to GRB physics and could serve as an indicator of Γ0 for long GRBs without early afterglow detections. A comparison of the early X-ray and optical afterglow light curves shows that the early bright X-ray emission is usually dominated by a non-forward-shock component, but occasionally (for one case) the forward shock emission is observable, and an achromatic deceleration feature is observed. The superposition of the internal and external components in X-rays causes the diversity of the observed X-ray light curves.

The Supercritical Pile Model for GRBs

NASA Technical Reports Server (NTRS)

Kazanas, D.

2005-01-01

We present the spectral and temporal radiative signatures expected within the "Supercritical Pile" model of Gamma Ray Bursts (GRB). This model is motivated by the need for a process that provides the dissipation necessary in GRB and presents a well defined scheme for converting the energy stored in the relativistic protons of the Relativistic Blast Waves (RBW) associated with GRB into radiation; at the same time it leads to spectra which exhibit a peak in the burst nuF(sub nu) distribution at an energy E(sub p) approx. equal to 1 MeV in the observer s frame, in agreement with observation and largely independent of the Lorentz factor r of the associated relativistic outflow. Futhermore, this scheme does not require (but does not preclude) acceleration of particles at the shock other than that provided by the isotropization of the flow bulk kinetic energy on the RBW frame. In the present paper we model in detail the evolution of protons, electrons and photons from a RBW to produce detailed spectra of the prompt GRB phase as a function of time from across a very broad range spanning roughly 4 log10Gamma decades in frequency. The model spectra are in general agreement with observations and provide a means for the delineating of the model parameters through direct comparison with trends observed in GRB properties.

The Supercritical Pile Model for GRBs

NASA Technical Reports Server (NTRS)

Kazanas, Demos

2005-01-01

We present the spectral and tempora1 radiative signatures expected within the "Supercritical Pile" model of Gamma Ray Bursts (GRB). This model is motivated by the need for a process that provides the dissipation necessary in GRB and presents a well defined theme for converting the energy stored in the relativistic protons of the Relativistic Blast Waves (RBW) associated with GRB into radiation; at the same it leads to spectra which exhibit a peak in the burst vFv, distribution at an energy Ep l. MeV in the observer's frame, in agreement with observation and largely independent of the Lorentz factor P of the associated relativistic outflow. Furthermore, this scheme does not require (but does not preclude) acceleration of particles at the shock other than that provided by the isotropization of the flow kinetic energy on the RBW frame. In the present paper we model in detail the evolution of protons, electrons and photons from a RBW within the framework of this model to produce detailed spectra of the prompt GRB phase as a function of time from across a very broad range spanning roughly 4log10P decades in frequency. The model spectra are in general agreement with observations and provide a means for the delineating of the model parameters through direct comparison with trends observed in GRB properties.

The Supercritical Pile Model for GRBs

NASA Technical Reports Server (NTRS)

Kazanas, Demos

2006-01-01

We present the spectral and temporal radiative signatures expected within the Supercritical Pile model of Gamma Ray Bursts (GRB). This model is motivated by the need for a process that provides the dissipation necessary in GRB and presents a well defined scheme for converting the energy stored in the relativistic protons of the Relativistic Blast Waves (RBW) associated with GRB into radiation; at the same time it leads to spectra which exhibit a peak in the burst nuF(sub nu) distribution at an energy E(sub p) approximately equal to 1 MeV in the observer s frame, in agreement with observation and largely independent of the Lorentz factor GAMMA of the associated relativistic outflow. Furthermore, this scheme does not require (but does not preclude) acceleration of particles at the shock other than that provided by the isotropization of the flow bulk kinetic energy on the RBW frame. In the present paper we model in detail the evolution of protons, electrons and photons from a RBW to produce detailed spectra of the prompt GRB phase as a function of time from across a very broad range spanning roughly 4 log10 GAMMA decades in frequency. The model spectra are in general agreement with observations and provide a means for the delineating of the model parameters through direct comparison with trends observed in GRB properties.

A Reverse Shock and Unusual Radio Properties in GRB 160625B

NASA Astrophysics Data System (ADS)

Alexander, K. D.; Laskar, T.; Berger, E.; Guidorzi, C.; Dichiara, S.; Fong, W.; Gomboc, A.; Kobayashi, S.; Kopac, D.; Mundell, C. G.; Tanvir, N. R.; Williams, P. K. G.

2017-10-01

We present multi-wavelength observations and modeling of the exceptionally bright long γ-ray burst GRB 160625B. The optical and X-ray data are well fit by synchrotron emission from a collimated blastwave with an opening angle of {θ }j≈ 3\\buildrel{\\circ}\\over{.} 6 and kinetic energy of {E}K≈ 2× {10}51 erg, propagating into a low-density (n≈ 5× {10}-5 cm-3) medium with a uniform profile. The forward shock is sub-dominant in the radio band; instead, the radio emission is dominated by two additional components. The first component is consistent with emission from a reverse shock, indicating an initial Lorentz factor of {{{Γ }}}0≳ 100 and an ejecta magnetization of {R}B≈ 1{--}100. The second component exhibits peculiar spectral and temporal evolution and is most likely the result of scattering of the radio emission by the turbulent Milky Way interstellar medium (ISM). Such scattering is expected in any sufficiently compact extragalactic source and has been seen in GRBs before, but the large amplitude and long duration of the variability seen here are qualitatively more similar to extreme scattering events previously observed in quasars, rather than normal interstellar scintillation effects. High-cadence, broadband radio observations of future GRBs are needed to fully characterize such effects, which can sensitively probe the properties of the ISM and must be taken into account before variability intrinsic to the GRB can be interpreted correctly.

Accretion and Outflow from a Magnetized, Neutrino Cooled Torus around the Gamma Ray Burst Central Engine

NASA Astrophysics Data System (ADS)

Janiuk, Agnieszka; Moscibrodzka, Monika

Gamma Ray Bursts (GRB) are the extremely energetic transient events, visible from the most distant parts of the Universe. They are most likely powered by accretion on the hyper-Eddington rates that proceeds onto a newly born stellar mass black hole. This central engine gives rise to the most powerful, high Lorentz factor jets that are responsible for energetic gamma ray emission. We investigate the accretion flow evolution in GRB central engine, using the 2D MHD simulations in General Relativity. We compute the structure and evolution of the extremely hot and dense torus accreting onto the fast spinning black hole, which launches the magnetized jets. We calculate the chemical structure of the disk and account for neutrino cooling. Our preliminary runs apply to the short GRB case (remnant torus accreted after NS-NS or NS-BH merger). We estimate the neutrino luminosity of such an event for chosen disk and central BH mass.

On the Neutrino Non-detection of GRB 130427A

NASA Astrophysics Data System (ADS)

Gao, Shan; Kashiyama, Kazumi; Mészáros, Peter

2013-07-01

The recent gamma-ray burst GRB 130427A has an isotropic electromagnetic energy E iso ~ 1054 erg, suggesting an ample supply of target photons for photo-hadronic interactions, which at its low redshift of z ~ 0.34 would appear to make it a promising candidate for neutrino detection. However, the IceCube collaboration has reported a null result based on a search during the prompt emission phase. We show that this neutrino non-detection can provide valuable information about this gamma-ray burst's (GRB's) key physical parameters such as the emission radius Rd , the bulk Lorentz factor Γ, and the energy fraction converted into cosmic rays epsilon p . The results are discussed both in a model-independent way and in the specific scenarios of an internal shock (IS) model, a baryonic photospheric (BPH) model, and a magnetic photospheric (MPH) model. We find that the constraints are most stringent for the MPH model considered, but the constraints on the IS and the BPH models are fairly modest.

Exploring the Properties of Choked Gamma-ray Bursts with IceCube’s High-energy Neutrinos

NASA Astrophysics Data System (ADS)

Denton, Peter B.; Tamborra, Irene

2018-03-01

Long duration gamma-ray bursts (GRBs) have often been considered the natural evolution of some core-collapse supernova (CCSN) progenitors. However, the fraction of CCSNe linked to astrophysical jets and their properties are still poorly constrained. While any successful astrophysical jet harbored in a CCSN should produce high-energy neutrinos, photons may be able to successfully escape the stellar envelope only for a fraction of progenitors, possibly leading to the existence of high-luminosity, low-luminosity, and not-electromagnetically bright (“choked”) GRBs. By postulating a CCSN–GRB connection, we accurately model the jet physics within the internal-shock GRB model and assume scaling relations for the GRB parameters that depend on the Lorentz boost factor Γ. The IceCube high-energy neutrino flux is then employed as an upper limit of the neutrino background from electromagnetically bright and choked GRBs to constrain the jet and the progenitor properties. The current IceCube data set is compatible with up to 1% of all CCSNe harboring astrophysical jets. Interestingly, those jets are predominantly choked. Our findings suggest that neutrinos can be powerful probes of the burst physics and can provide major insights on the CCSN–GRB connection.

Polarization of Gamma-Ray Bursts in the Dissipative Photosphere Model

NASA Astrophysics Data System (ADS)

Lundman, Christoffer; Vurm, Indrek; Beloborodov, Andrei M.

2018-04-01

The MeV spectral peak of gamma-ray bursts (GRBs) is best explained as photospheric emission from a dissipative relativistic jet. The observed non-blackbody spectrum shows that sub-photospheric dissipation involves both thermal plasma heating and injection of nonthermal particles, which quickly cool through inverse Compton scattering and emission of synchrotron radiation. Synchrotron photons emitted around and above the photosphere are predicted to dominate the low-energy part of the GRB spectrum, starting from roughly a decade in energy below the MeV peak. We show that this leads to a unique polarization signature: a rise in GRB polarization toward lower energies. We compute the polarization degree of GRB radiation as a function of photon energy for a generic jet model, and show the predictions for GRBs 990123, 090902B, and 110721A. The expected polarization is significant in the X-ray band, in particular for bursts similar to GRB 090902B. The model predicts that radiation in the MeV peak (and at higher energies) is unpolarized as long as the jet is approximately uniform on angular scales δθ ≳ Γ‑1 where Γ is the bulk Lorentz factor of the jet.

The Supercritical Pile GRB Model: The Prompt to Afterglow Evolution

NASA Technical Reports Server (NTRS)

Mastichiadis, A.; Kazanas, D.

2009-01-01

The "Supercritical Pile" is a very economical GRB model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at energy approx. 1 MeV. We extend this model to include the evolution of the RBW Lorentz factor Gamma and thus follow its spectral and temporal features into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model can be the sources of rich time evolution which we have began to explore. In particular. one can this may obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the (nu)F(sub nu), spectra. In this note we present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

What can we learn from "internal plateaus"? The peculiar afterglow of GRB 070110

NASA Astrophysics Data System (ADS)

Beniamini, P.; Mochkovitch, R.

2017-09-01

Context. The origin of the prompt emission of gamma-ray bursts is highly debated. Proposed scenarios involve various dissipation processes (shocks, magnetic reconnection, and inelastic collisions) above or below the photosphere of an ultra-relativistic outflow. Aims: We search for observational features that could help to favour one scenario over the others by constraining the dissipation radius, the magnetization of the outflow, or by indicating the presence of shocks. Bursts showing peculiar behaviours can emphasize the role of a specific physical ingredient, which becomes more apparent under certain circumstances. Methods: We study GRB 070110, which exhibited several remarkable features during its early afterglow; I.e. a very flat plateau terminated by an extremely steep drop and immediately followed by a bump. We modelled the plateau as the photospheric emission from a long-lasting outflow of moderate Lorentz factor (Γ 20), which lags behind an ultra-relativistic (Γ > 100) ejecta that is responsible for the prompt emission. We computed the dissipation of energy in the forward and reverse shocks resulting from the deceleration of this ejecta by the external medium (uniform or stellar wind). Results: We find that photospheric emission from the long-lasting outflow can account for the plateau properties (luminosity and spectrum) assuming that some dissipation takes place in the flow. The geometrical timescale at the photospheric radius is so short that the observed decline at the end of the plateau likely corresponds to the actual shutdown of the activity in the central engine. The bump that follows results from the power dissipated in the reverse shock, which develops when the material making the plateau catches up with the initially fast shell in front, after the fast shell has decelerated. Conclusions: The proposed interpretation suggests that the prompt phase results from dissipation above the photosphere while the plateau has a photospheric origin. If the bump is produced by the reverse shock, it implies an upper limit (σ ≲ 0.1) on the magnetization of the low Γ material making the plateau. A plateau that is terminated by a drop as steep as in GRB 070110 was not observed in any other long burst. It could mean that persistent outflows are very uncommon or that the plateau luminosity or the energy of the emitted photons are generally much lower because the outflow remains mostly adiabatic or has a Lorentz factor below 10.

A multiwavelength study of Swift GRB 060111B constraining the origin of its prompt optical emission

NASA Astrophysics Data System (ADS)

Stratta, G.; Pozanenko, A.; Atteia, J.-L.; Klotz, A.; Basa, S.; Gendre, B.; Verrecchia, F.; Boër, M.; Cutini, S.; Henze, M.; Holland, S.; Ibrahimov, M.; Ienna, F.; Khamitov, I.; Klose, S.; Rumyantsev, V.; Biryukov, V.; Sharapov, D.; Vachier, F.; Arnouts, S.; Perley, D. A.

2009-09-01

Context: The detection of bright optical emission measured with good temporal resolution during the prompt phase of GRB 060111Bmakes this GRB a rare event that is especially useful for constraining theories of the prompt emission. Aims: For this reason an extended multi-wavelength campaign was performed to further constrain the physical interpretation of the observations. Methods: In this work, we present the results obtained from our multi-wavelength campaign, as well as from the public Swift/BAT, XRT, and UVOT data. Results: We identified the host galaxy at R˜25 mag from deep R-band exposures taken 5 months after the trigger. Its featureless spectrum and brightness, as well as the non-detection of any associated supernova 16 days after the trigger, enabled us to constrain the distance scale of GRB 060111B11 within 0.4≤ z ≤3 in the most conservative case. The host galaxy spectral continuum is best fit with a redshift of z˜2, and other independent estimates converge to z˜1-2. From the analysis of the early afterglow SED, we find that non-negligible host galaxy dust extinction, in addition to the Galactic one, affects the observed flux in the optical regime. The extinction-corrected optical-to-gamma-ray SED during the prompt emission shows a flux density ratio Fγ/F_opt=10-2-10-4 with spectral index βγ,opt > βγ, strongly suggesting a separate origin of the optical and gamma-ray components. This result is supported by the lack of correlated behavior in the prompt emission light curves observed in the two energy domains. The temporal properties of the prompt optical emission observed during GRB 060111B11 and their similarities to other rapidly-observed events favor interpretation of this optical light as radiation from the reverse shock. Observations are in good agreement with theoretical expectations for a thick shell limit in slow cooling regime. The expected peak flux is consistent with the observed one corrected for the host extinction, likely indicating that the starting time of the TAROT observations is very near to or coincident with the peak time. The estimated fireball initial Lorentz factor is Γ≥260-360 at z=1-2, similar to the Lorentz factors obtained from other GRBs. GRB 060111B11 is a rare case of a GRB with both a bright, well-observed optical counterpart and a “canonical” early X-ray light curve, thus providing a good test case of the reverse shock emission mechanism in both energy ranges. Based on observations performed with: TAROT at the Calern observatory. The Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. CFHT, which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the CNRS of France, and the University of Hawaii. The 2.6 m Shajn telescope at the Crimean Astrophysical Observatory. Some of the data presented here were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Prompt optical emission from gamma-ray bursts with multiple timescale variability of central engine activities

NASA Astrophysics Data System (ADS)

Xu, Si-Yao; Li, Zhuo

2014-04-01

Complete high-resolution light curves of GRB 080319B observed by Swift present an opportunity for detailed temporal analysis of prompt optical emission. With a two-component distribution of initial Lorentz factors, we simulate the dynamical process of shells being ejected from the central engine in the framework of the internal shock model. The emitted radiations are decomposed into different frequency ranges for a temporal correlation analysis between the light curves in different energy bands. The resulting prompt optical and gamma-ray emissions show similar temporal profiles, with both showing a superposition of a component with slow variability and a component with fast variability, except that the gamma-ray light curve is much more variable than its optical counterpart. The variability in the simulated light curves and the strong correlation with a time lag between the optical and gamma-ray emissions are in good agreement with observations of GRB 080319B. Our simulations suggest that the variations seen in the light curves stem from the temporal structure of the shells injected from the central engine of gamma-ray bursts. Future observations with high temporal resolution of prompt optical emission from GRBs, e.g., by UFFO-Pathfinder and SVOM-GWAC, will provide a useful tool for investigating the central engine activity.

Multiwavelength Observations of GRB 110731A: GeV Emission From Onset to Afterglow

DOE PAGES

Ackermann, M.; Ajello, M.; Asano, K.; ...

2013-01-09

In this paper, we report on the multiwavelength observations of the bright, long gamma-ray burst GRB 110731A, by the Fermi and Swift observatories, and by the MOA and GROND optical telescopes. The analysis of the prompt phase reveals that GRB 110731A shares many features with bright Large Area Telescope bursts observed by Fermi during the first three years on-orbit: a light curve with short time variability across the whole energy range during the prompt phase, delayed onset of the emission above 100 MeV, extra power-law component and temporally extended high-energy emission. In addition, this is the first GRB for whichmore » simultaneous GeV, X-ray, and optical data are available over multiple epochs beginning just after the trigger time and extending for more than 800 s, allowing temporal and spectral analysis in different epochs that favor emission from the forward shock in a wind-type medium. Lastly, the observed temporally extended GeV emission is most likely part of the high-energy end of the afterglow emission. Both the single-zone pair transparency constraint for the prompt signal and the spectral and temporal analysis of the forward-shock afterglow emission independently lead to an estimate of the bulk Lorentz factor of the jet Γ ~ 500-550.« less

Multiwavelength Observations of GRB 110731A: GeV Emission from Onset to Afterglow

NASA Astrophysics Data System (ADS)

Ackermann, M.; Ajello, M.; Asano, K.; Baldini, L.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bellazzini, R.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fegan, S. J.; Focke, W. B.; Franckowiak, A.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Granot, J.; Greiner, J.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mazziotta, M. N.; McEnery, J. E.; Mehault, J.; Mészáros, P.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paneque, D.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Romoli, C.; Roth, M.; Ryde, F.; Sanchez, D. A.; Sgrò, C.; Siskind, E. J.; Sonbas, E.; Spinelli, P.; Stamatikos, M.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Troja, E.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Winer, B. L.; Wood, K. S.; Yang, Z.; Gruber, D.; Bhat, P. N.; Bissaldi, E.; Briggs, M. S.; Burgess, J. M.; Connaughton, V.; Foley, S.; Kippen, R. M.; Kouveliotou, C.; McBreen, S.; McGlynn, S.; Paciesas, W. S.; Pelassa, V.; Preece, R.; Rau, A.; van der Horst, A. J.; von Kienlin, A.; Kann, D. A.; Filgas, R.; Klose, S.; Krühler, T.; Fukui, A.; Sako, T.; Tristram, P. J.; Oates, S. R.; Ukwatta, T. N.; Littlejohns, O.

2013-02-01

We report on the multiwavelength observations of the bright, long gamma-ray burst GRB 110731A, by the Fermi and Swift observatories, and by the MOA and GROND optical telescopes. The analysis of the prompt phase reveals that GRB 110731A shares many features with bright Large Area Telescope bursts observed by Fermi during the first three years on-orbit: a light curve with short time variability across the whole energy range during the prompt phase, delayed onset of the emission above 100 MeV, extra power-law component and temporally extended high-energy emission. In addition, this is the first GRB for which simultaneous GeV, X-ray, and optical data are available over multiple epochs beginning just after the trigger time and extending for more than 800 s, allowing temporal and spectral analysis in different epochs that favor emission from the forward shock in a wind-type medium. The observed temporally extended GeV emission is most likely part of the high-energy end of the afterglow emission. Both the single-zone pair transparency constraint for the prompt signal and the spectral and temporal analysis of the forward-shock afterglow emission independently lead to an estimate of the bulk Lorentz factor of the jet Γ ~ 500-550.

Dynamic Monte Carlo simulations of radiatively accelerated GRB fireballs

NASA Astrophysics Data System (ADS)

Chhotray, Atul; Lazzati, Davide

2018-05-01

We present a novel Dynamic Monte Carlo code (DynaMo code) that self-consistently simulates the Compton-scattering-driven dynamic evolution of a plasma. We use the DynaMo code to investigate the time-dependent expansion and acceleration of dissipationless gamma-ray burst fireballs by varying their initial opacities and baryonic content. We study the opacity and energy density evolution of an initially optically thick, radiation-dominated fireball across its entire phase space - in particular during the Rph < Rsat regime. Our results reveal new phases of fireball evolution: a transition phase with a radial extent of several orders of magnitude - the fireball transitions from Γ ∝ R to Γ ∝ R0, a post-photospheric acceleration phase - where fireballs accelerate beyond the photosphere and a Thomson-dominated acceleration phase - characterized by slow acceleration of optically thick, matter-dominated fireballs due to Thomson scattering. We quantify the new phases by providing analytical expressions of Lorentz factor evolution, which will be useful for deriving jet parameters.

Detection of a Spectral Break in the Extra Hard Component of GRB 090926A

NASA Astrophysics Data System (ADS)

Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bhat, P. N.; Bissaldi, E.; Blandford, R. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chaplin, V.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Cutini, S.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Dingus, B. L.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Goldstein, A.; Granot, J.; Greiner, J.; Grenier, I. A.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hayashi, K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Itoh, R.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Llena Garde, M.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McBreen, S.; McEnery, J. E.; McGlynn, S.; Meegan, C.; Mehault, J.; Mészáros, P.; Michelson, P. F.; Mizuno, T.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann-Godo, M.; Nishino, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Petrosian, V.; Piron, F.; Porter, T. A.; Preece, R.; Racusin, J. L.; Rainò, S.; Rando, R.; Rau, A.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Reyes, L. C.; Ripken, J.; Ritz, S.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Stecker, F. W.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Tanaka, Y.; Thayer, J. B.; Thayer, J. G.; Tibaldo, L.; Tierney, D.; Toma, K.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; Vandenbroucke, J.; van der Horst, A. J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; von Kienlin, A.; Waite, A. P.; Wang, P.; Wilson-Hodge, C.; Winer, B. L.; Wood, K. S.; Wu, X. F.; Yamazaki, R.; Yang, Z.; Ylinen, T.; Ziegler, M.

2011-03-01

We report on the observation of the bright, long gamma-ray burst, GRB 090926A, by the Gamma-ray Burst Monitor and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. GRB 090926A shares several features with other bright LAT bursts. In particular, it clearly shows a short spike in the light curve that is present in all detectors that see the burst, and this in turn suggests that there is a common region of emission across the entire Fermi energy range. In addition, while a separate high-energy power-law component has already been observed in other gamma-ray bursts, here we report for the first time the detection with good significance of a high-energy spectral break (or cutoff) in this power-law component around 1.4 GeV in the time-integrated spectrum. If the spectral break is caused by opacity to electron-positron pair production within the source, then this observation allows us to compute the bulk Lorentz factor for the outflow, rather than a lower limit.

Detection of a spectral break in the extra hard component of GRB 090926A

DOE PAGES

Ackermann, M.; Ajello, M.; Asano, K.; ...

2011-02-16

Here, we report on the observation of the bright, long gamma-ray burst, GRB 090926A, by the Gamma-ray Burst Monitor and Large Area Telescope (LAT) instruments on board the Fermi Gamma-ray Space Telescope. GRB 090926A shares several features with other bright LAT bursts. In particular, it clearly shows a short spike in the light curve that is present in all detectors that see the burst, and this in turn suggests that there is a common region of emission across the entire Fermi energy range. In addition, while a separate high-energy power-law component has already been observed in other gamma-ray bursts, heremore » we report for the first time the detection with good significance of a high-energy spectral break (or cutoff) in this power-law component around 1.4 GeV in the time-integrated spectrum. If the spectral break is caused by opacity to electron-positron pair production within the source, then this observation allows us to compute the bulk Lorentz factor for the outflow, rather than a lower limit.« less

iPTF Archival Search for Fast Optical Transients

NASA Astrophysics Data System (ADS)

Ho, Anna Y. Q.; Kulkarni, S. R.; Nugent, Peter E.; Zhao, Weijie; Rusu, Florin; Cenko, S. Bradley; Ravi, Vikram; Kasliwal, Mansi M.; Perley, Daniel A.; Adams, Scott M.; Bellm, Eric C.; Brady, Patrick; Fremling, Christoffer; Gal-Yam, Avishay; Kann, David Alexander; Kaplan, David; Laher, Russ R.; Masci, Frank; Ofek, Eran O.; Sollerman, Jesper; Urban, Alex

2018-02-01

There has been speculation about a class of relativistic explosions with an initial Lorentz factor Γinit smaller than that of classical gamma-ray bursts (GRBs). These “dirty fireballs” would lack prompt GRB emission but could be pursued via their optical afterglow, appearing as transients that fade overnight. Here we report a search for such transients (that fade by 5-σ in magnitude overnight) in four years of archival photometric data from the intermediate Palomar Transient Factory (iPTF). Our search criteria yielded 50 candidates. Of these, two were afterglows to GRBs that had been found in dedicated follow-up observations to triggers from the Fermi GRB Monitor. Another (iPTF14yb) was a GRB afterglow discovered serendipitously. Eight were spurious artifacts of reference image subtraction, and one was an asteroid. The remaining 38 candidates have red stellar counterparts in external catalogs. The photometric and spectroscopic properties of the counterparts identify these transients as strong flares from M dwarfs of spectral type M3–M7 at distances of d ≈ 0.15–2.1 kpc; three counterparts were already spectroscopically classified as late-type M stars. With iPTF14yb as the only confirmed relativistic outflow discovered independently of a high-energy trigger, we constrain the all-sky rate of transients that peak at m = 18 and fade by Δm = 2 mag in Δt = 3 hr to be 680 {{yr}}-1, with a 68% confidence interval of 119{--}2236 {{yr}}-1. This implies that the rate of visible dirty fireballs is at most comparable to that of the known population of long-duration GRBs.

iPTF Archival Search for Fast Optical Transients

DOE PAGES

Ho, Anna Y. Q.; Kulkarni, S. R.; Nugent, Peter E.; ...

2018-02-09

There has been speculation about a class of relativistic explosions with an initial Lorentz factor Γ init smaller than that of classical gamma-ray bursts (GRBs). These "dirty fireballs" would lack prompt GRB emission but could be pursued via their optical afterglow, appearing as transients that fade overnight. We report a search for such transients (that fade by 5-σ in magnitude overnight) in four years of archival photometric data from the intermediate Palomar Transient Factory (iPTF). Our search criteria yielded 50 candidates. Of these, two were afterglows to GRBs that had been found in dedicated follow-up observations to triggers from themore » Fermi GRB Monitor. Another (iPTF14yb) was a GRB afterglow discovered serendipitously. Eight were spurious artifacts of reference image subtraction, and one was an asteroid. The remaining 38 candidates have red stellar counterparts in external catalogs. The photometric and spectroscopic properties of the counterparts identify these transients as strong flares from M dwarfs of spectral type M3-M7 at distances of d ≈ 0.15-2.1 kpc; three counterparts were already spectroscopically classified as late-type M stars. With iPTF14yb as the only confirmed relativistic outflow discovered independently of a high-energy trigger, we constrain the all-sky rate of transients that peak at m = 18 and fade by Δm = 2 mag in Δt = 3 hr to be 680 yr -1, with a 68% confidence interval of 1119-2236 yr -1. This implies that the rate of visible dirty fireballs is at most comparable to that of the known population of long-duration GRBs.« less

Multi-wavelength Observations of GRB 111228A and Implications for the Fireball and its Environment

NASA Astrophysics Data System (ADS)

Xin, Li-Ping; Wang, Yuan-Zhu; Lin, Ting-Ting; Liang, En-Wei; Lü, Hou-Jun; Zhong, Shu-Qing; Urata, Yuji; Zhao, Xiao-Hong; Wu, Chao; Wei, Jian-Yan; Huang, Kui-Yun; Qiu, Yu-Lei; Deng, Jin-Song

2016-02-01

Observations of very early multi-wavelength afterglows are critical to reveal the properties of the radiating fireball and its environment as well as the central engine of gamma-ray bursts (GRBs). We report our optical observations of GRB 111228A from 95 s to about 50 hr after the burst trigger and investigate its properties of the prompt gamma-rays and the ambient medium using our data and the data from the Swift and Fermi missions. Our joint optical and X-ray spectral fits to the afterglow data show that the ambient medium features a low dust-to-gas ratio. Incorporating the energy injection effect, our best fit to the afterglow light curves with the standard afterglow model via the Markov Chain Monte Carlo technique shows that {ɛ }e=(6.9+/- 0.3)× {10}-2, {ɛ }B=(7.73+/- 0.62)× {10}-6,{E}K=(6.32+/- 0.86)× {10}53 {erg}, n=0.100+/- 0.014 cm-3. The low medium density likely implies that the afterglow jet may be in a halo or in a hot ISM. A chromatic shallow decay segment observed in the optical and X-ray bands is well explained with the long-lasting energy injection from the central engine, which would be a magnetar with a period of about 1.92 ms inferred from the data. The Ep of its time-integrated prompt gamma-ray spectrum is ˜26 KeV. Using the initial Lorentz factor ({{{Γ }}}0={476}-237+225) derived from our afterglow model fit, it is found that GRB 111228A satisfies the {L}{{iso}}-{E}p,z-{{{Γ }}}0 relation and bridges the typical GRBs and low luminosity GRBs in this relation.

New Fermi-LAT event reconstruction reveals more high-energy gamma rays from gamma-ray bursts

DOE PAGES

Atwood, W. B.; Baldini, L.; Bregeon, J.; ...

2013-08-19

Here, based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Largemore » Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy (~147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.« less

The supercritical pile gamma-ray burst model: The GRB afterglow steep decline and plateau phase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sultana, J.; Kazanas, D.; Mastichiadis, A., E-mail: joseph.sultana@um.edu.mt

2013-12-10

We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the 'supercritical pile' GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E {sub pk} ∼ m{sub e}c {sup 2}. We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Γ to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (∼25%)more » decrease in Γ at a radius that is smaller (depending on conditions) than the deceleration radius R{sub D} . Because of this reduction, the kinematic criticality criterion of the 'supercritical pile' is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by ∼m{sub p} /m{sub e} than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R{sub D} , the RBW internal energy continues to drive the RBW expansion at a constant (new) Γ and its X-ray luminosity remains constant until R{sub D} is reached, at which point it resumes its more conventional decay, thereby completing the 'unexpected' XRT light curve phase. If this transition occurs at R ≅ R{sub D} , the steep decline is followed by a flux decrease instead of a 'plateau,' consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R ≅ R{sub D} , thus providing novel insights into GRB phenomenology.« less

The Supercritical Pile Gamma-Ray Burst Model: The GRB Afterglow Steep Decline and Plateau Phase

NASA Technical Reports Server (NTRS)

Sultana, Joseph; Kazanas, D.; Mastichiadis, A.

2013-01-01

We present a process that accounts for the steep decline and plateau phase of the Swift X-Ray Telescope (XRT) light curves, vexing features of gamma-ray burst (GRB) phenomenology. This process is an integral part of the "supercritical pile" GRB model, proposed a few years ago to account for the conversion of the GRB kinetic energy into radiation with a spectral peak at E(sub pk) is approx. m(sub e)C(exp 2). We compute the evolution of the relativistic blast wave (RBW) Lorentz factor Gamma to show that the radiation-reaction force due to the GRB emission can produce an abrupt, small (approx. 25%) decrease in Gamma at a radius that is smaller (depending on conditions) than the deceleration radius R(sub D). Because of this reduction, the kinematic criticality criterion of the "supercritical pile" is no longer fulfilled. Transfer of the proton energy into electrons ceases and the GRB enters abruptly the afterglow phase at a luminosity smaller by approx. m(sub p)/m(sub e) than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than R(sub D), the RBW internal energy continues to drive the RBW expansion at a constant (new) Gamma and its X-ray luminosity remains constant until R(sub D) is reached, at which point it resumes its more conventional decay, thereby completing the "unexpected" XRT light curve phase. If this transition occurs at R is approx. equal to R(sub D), the steep decline is followed by a flux decrease instead of a "plateau," consistent with the conventional afterglow declines. Besides providing an account of these peculiarities, the model suggests that the afterglow phase may in fact begin before the RBW reaches R is approx. equal to R(sub D), thus providing novel insights into GRB phenomenology.

GRB 120422A: a Low-Luminosity Gamma-Ray Burst Driven by a Central Engine

NASA Technical Reports Server (NTRS)

Zhang, Bin-Bin; Fan, Yi-Zhong; Shen, Rong-Feng; Xu, Dong; Zhang, Fu-Wen; Wei, Da-Ming; Burrows, David N.; Zhang, Bing; Gehrels, Neil

2012-01-01

GRB 120422A is a low-luminosity gamma-ray burst (GRB) associated with a bright supernova, which distinguishesitself by its relatively short T(sub 90) (approximately 5 s) and an energetic and steep-decaying X-ray tail. We analyze the Swift BurstAlert Telescope and X-ray Telescope data and discuss the physical implications. We show that the steep declineearly in the X-ray light curve can be interpreted as the curvature tail of a late emission episode around 58-86 s,with a curved instantaneous spectrum at the end of the emission episode. Together with the main activity in thefirst 20 s and the weak emission from 40 s to 60 s, the prompt emission is variable, which points to a centralengine origin in contrast to a shock-breakout origin, which is used to interpret some other nearby low-luminosity supernova GRBs. Both the curvature effect model and interpreting the early shallow decay as the coasting externalforward shock emission in a wind medium provide a constraint on the bulk Lorentz factor to be around several.Comparing the properties ofGRB 120422A and other supernova GRBs,we find that themain criterion to distinguish engine-driven GRBs from shock-breakout GRBs is the time-averaged -ray luminosity. Engine-driven GRBs likelyhave a luminosity above approximately 10(sup 48) erg s(sup -1).

A Bulk Comptonization Model for the Prompt GRM Emission

NASA Technical Reports Server (NTRS)

Kazanas, Demos; Mastichiadis, A.

2010-01-01

The "Supercritical Pile" is a very economical GRB model that provides for the efficient conversion of the energy stored in the protons of a Relativistic Blast Wave (RBW) into radiation and at the same time produces - in the prompt GRB phase, even in the absence of any particle acceleration - a spectral peak at energy approximately 1 MeV. We extend this model to include the evolution of the RBW Lorentz factor F and thus follow its spectral and temporal features into the early GRB afterglow stage. One of the novel features of the present treatment is the inclusion of the feedback of the GRB produced radiation on the evolution of Gamma with radius. This feedback and the presence of kinematic and dynamic thresholds in the model are sources of potentially very rich time evolution which we have began to explore. In particular, one can this way obtain afterglow light curves with steep decays followed by the more conventional flatter afterglow slopes, while at the same time preserving the desirable features of the model, i.e. the well defined relativistic electron source and radiative processes that produce the proper peak in the nu F(sub nu) spectra. In this note we present the results of a specific set of parameters of this model with emphasis on the multiwavelength prompt emission and transition to the early afterglow.

Possible Class of Nearby Gamma-Ray Burst / Gravitational Wave Sources

NASA Astrophysics Data System (ADS)

Norris, Jay P.

2003-10-01

A possible subclass of gamma-ray bursts - those with few, wide pulses, spectral lags of order one to several seconds, and soft spectra - has been identified. Their Log[N]-Log[Fp] distribution approximates a -3/2 power-law, suggesting homogeneity and relatively nearby sources. These mostly dim bursts account for ~ 50% of the BATSE sample of long bursts near that instrument's trigger threshold, suggesting that this subluminous class constitutes a more common variety than the more familiar burst sources which lie at truly cosmological distances. Theoretical scenarios predicted such a class, motivated by their exemplar GRB 980425 (SN 1998bw) lying at a distance of ~ 38 Mpc. The observations are explained by invoking off-axis viewing of the GRB jet and/or bulk Lorentz factors of order a few. Long-lag bursts show a tendency to concentrate near the Supergalactic Plane with a quadrupole moment of -0.10 +/- 0.04, similar to that for SNe type Ib/c within the same volume. The rate of the observed subluminous bursts is of order 14 that of SNe Ib/c. Evidence for a sequential relationship between SNe Ib/c and GRBs is critiqued for two cases, as simultaneity of the SN and GRB events may be important for detection of the expected gravitational wave signal; at most, SN to GRB delays appear to be a few days. SN asymmetries and ultrarelativistic GRB jets suggest the possibility of rapid rotation in the pre-collapse objects, a primary condition required for highly non-axisymmetric SN collapse to produce strong gravitational waves.

The Supercritical Pile Model: Prompt Emission Across the Electromagnetic Spectrum

NASA Technical Reports Server (NTRS)

Kazanas, Demos; Mastichiadis, A.

2008-01-01

The "Supercritical Pile" GRB model is an economical model that provides the dissipation necessary to convert explosively the energy stored in relativistic protons in the blast wave of a GRB into radiation; at the same time it produces spectra whose luminosity peaks at 1 MeV in the lab frame, the result of the kinematics of the proton-photon - pair production reaction that effects the conversion of proton energy to radiation. We outline the fundamental notions behind the "Supercritical Pile" model and discuss the resulting spectra of the prompt emission from optical to gamma-ray energies of order Gamma^2 m_ec^2, (Gamma is the Lorentz factor of the blast wave) present even in the absence of an accelerated particle distribution and compare our results to bursts that cover this entire energy range. Particular emphasis is given on the emission at the GLAST energy range both in the prompt and the afterglow stages of the burst.

GRAVITATIONAL-WAVE OBSERVATIONS MAY CONSTRAIN GAMMA-RAY BURST MODELS: THE CASE OF GW150914–GBM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veres, P.; Preece, R. D.; Goldstein, A.

The possible short gamma-ray burst (GRB) observed by Fermi /GBM in coincidence with the first gravitational-wave (GW) detection offers new ways to test GRB prompt emission models. GW observations provide previously inaccessible physical parameters for the black hole central engine such as its horizon radius and rotation parameter. Using a minimum jet launching radius from the Advanced LIGO measurement of GW 150914, we calculate photospheric and internal shock models and find that they are marginally inconsistent with the GBM data, but cannot be definitely ruled out. Dissipative photosphere models, however, have no problem explaining the observations. Based on the peakmore » energy and the observed flux, we find that the external shock model gives a natural explanation, suggesting a low interstellar density (∼10{sup −3} cm{sup −3}) and a high Lorentz factor (∼2000). We only speculate on the exact nature of the system producing the gamma-rays, and study the parameter space of a generic Blandford–Znajek model. If future joint observations confirm the GW–short-GRB association we can provide similar but more detailed tests for prompt emission models.« less

Can the bump in the composite spectrum of GRB 910503 be an emission line feature of gamma-ray bursts?

NASA Astrophysics Data System (ADS)

Qin, Yi-Ping; Zhang, Fu-Wen

2005-12-01

Appearing in the composite spectral data of BATSE, EGRET and COMPTEL for GRB 910503, there is a bump at around 1600 keV. We perform a statistical analysis on the spectral data, trying to find out if the bump could be accounted for by a blue-shifted and significantly broadened rest frame line due to the Doppler effect of an expanding fireball surface. We made an F-test and adopted previously proposed criteria. The study reveals that the criteria are well satisfied and the feature can be interpreted as the blue shifted 6.4 keV line. From the fit with this line taken into account, we find the Lorentz factor of this source to be Γ = 116+9-9 (at the 68% confident level, triangleχ2 = 1) and the rest frame spectral peak energy to be E0,p = 2.96+0.24-0.18 keV. Although the existence of the emission line feature requires other independent tests to confirm, the analysis suggests that it is feasible to detect emission line features in the high energy range of GRB spectra when taking into account the Doppler effect of fireball expansion.

Efficiency of Magnetic to Kinetic Energy Conversion in a Monopole Magnetosphere

NASA Astrophysics Data System (ADS)

Tchekhovskoy, Alexander; McKinney, Jonathan C.; Narayan, Ramesh

2009-07-01

Unconfined relativistic outflows from rotating, magnetized compact objects are often well modeled by assuming that the field geometry is approximately a split-monopole at large radii. Earlier work has indicated that such an unconfined flow has an inefficient conversion of magnetic energy to kinetic energy. This has led to the conclusion that ideal magnetohydrodynamical (MHD) processes fail to explain observations of, e.g., the Crab pulsar wind at large radii where energy conversion appears efficient. In addition, as a model for astrophysical jets, the monopole field geometry has been abandoned in favor of externally confined jets since the latter appeared to be generically more efficient jet accelerators. We perform time-dependent axisymmetric relativistic MHD simulations in order to find steady-state solutions for a wind from a compact object endowed with a monopole field geometry. Our simulations follow the outflow for 10 orders of magnitude in distance from the compact object, which is large enough to study both the initial "acceleration zone" of the magnetized wind as well as the asymptotic "coasting zone." We obtain the surprising result that acceleration is actually efficient in the polar region, which develops a jet despite not being confined by an external medium. Our models contain jets that have sufficient energy to account for moderately energetic long and short gamma-ray burst (GRB) events (~1051-1052 erg), collimate into narrow opening angles (opening half-angle θ j ≈ 0.03 rad), become matter-dominated at large radii (electromagnetic energy flux per unit matter energy flux σ < 1), and move at ultrarelativistic Lorentz factors (γ j ~ 200 for our fiducial model). The simulated jets have γ j θ j ~ 5-15, so they are in principle capable of generating "achromatic jet breaks" in GRB afterglow light curves. By defining a "causality surface" beyond which the jet cannot communicate with a generalized "magnetic nozzle" near the axis of rotation, we obtain approximate analytical solutions for the Lorentz factor that fit the numerical solutions well. This allows us to extend our results to monopole wind models with arbitrary magnetization. Overall, our results demonstrate that the production of ultrarelativistic jets is a more robust process than previously thought.

Dynamics and stability of relativistic gamma-ray-bursts blast waves

NASA Astrophysics Data System (ADS)

Meliani, Z.; Keppens, R.

2010-09-01

Aims: In gamma-ray-bursts (GRBs), ultra-relativistic blast waves are ejected into the circumburst medium. We analyse in unprecedented detail the deceleration of a self-similar Blandford-McKee blast wave from a Lorentz factor 25 to the nonrelativistic Sedov phase. Our goal is to determine the stability properties of its frontal shock. Methods: We carried out a grid-adaptive relativistic 2D hydro-simulation at extreme resolving power, following the GRB jet during the entire afterglow phase. We investigate the effect of the finite initial jet opening angle on the deceleration of the blast wave, and identify the growth of various instabilities throughout the coasting shock front. Results: We find that during the relativistic phase, the blast wave is subject to pressure-ram pressure instabilities that ripple and fragment the frontal shock. These instabilities manifest themselves in the ultra-relativistic phase alone, remain in full agreement with causality arguments, and decay slowly to finally disappear in the near-Newtonian phase as the shell Lorentz factor drops below 3. From then on, the compression rate decreases to levels predicted to be stable by a linear analysis of the Sedov phase. Our simulations confirm previous findings that the shell also spreads laterally because a rarefaction wave slowly propagates to the jet axis, inducing a clear shell deformation from its initial spherical shape. The blast front becomes meridionally stratified, with decreasing speed from axis to jet edge. In the wings of the jetted flow, Kelvin-Helmholtz instabilities occur, which are of negligible importance from the energetic viewpoint. Conclusions: Relativistic blast waves are subject to hydrodynamical instabilities that can significantly affect their deceleration properties. Future work will quantify their effect on the afterglow light curves.

External Shock in a Multi-bursting Gamma-Ray Burst: Energy Injection Phase Induced by the Later Launched Ejecta

NASA Astrophysics Data System (ADS)

Lin, Da-Bin; Huang, Bao-Quan; Liu, Tong; Gu, Wei-Min; Mu, Hui-Jun; Liang, En-Wei

2018-01-01

Central engines of gamma-ray bursts (GRBs) may be intermittent and launch several episodes of ejecta separated by a long quiescent interval. In this scenario, an external shock is formed due to the propagation of the first launched ejecta into the circum-burst medium and the later launched ejecta may interact with the external shock at a later period. Owing to the internal dissipation, the later launched ejecta may be observed at a later time (t jet). In this paper, we study the relation of t b and t jet, where t b is the collision time of the later launched ejecta with the formed external shock. It is found that the relation of t b and t jet depends on the bulk Lorentz factor (Γjet) of the later launched ejecta and the density (ρ) of the circum-burst medium. If the value of Γjet or ρ is low, the t b would be significantly larger than t jet. However, the t b ∼ t jet can be found if the value of Γjet or ρ is significantly large. Our results can explain the large lag of the optical emission relative to the γ-ray/X-ray emission in GRBs, e.g., GRB 111209A. For GRBs with a precursor, our results suggest that the energy injection into the external shock and thus more than one external-reverse shock may appear in the main prompt emission phase. According to our model, we estimate the Lorentz factor of the second launched ejecta in GRB 160625B.

Propagation of partially coherent Lorentz and Lorentz-Gauss beams through a paraxial ABCD optical system in a turbulent atmosphere

NASA Astrophysics Data System (ADS)

Zhao, Chengliang; Cai, Yangjian

2011-05-01

Based on the generalized Huygens-Fresnel integral, propagation of partially coherent Lorentz and Lorentz-Gauss beams through a paraxial ABCD optical system in a turbulent atmosphere was investigated. Analytical propagation formulae were derived for the cross-spectral densities of partially coherent Lorentz and Lorentz-Gauss beams. As an application example, the focusing properties of partially coherent Gaussian, Lorentz and Lorentz-Gauss beams in a turbulent atmosphere and in free space were studied numerically and comparatively. It is found that the focusing properties of such beams are closely related to the initial coherence length and the structure constant of turbulence. By choosing a suitable initial coherence length, a partially coherent Lorentz beam can be focused more tightly than a Gaussian or Lorentz-Gauss beam in free space or in a turbulent atmosphere with small structure constant at the geometrical focal plane.

Fermi Observations of GRB 090510: A Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 keV to GeV Energies

DOE PAGES

Ackermann, M.; Asano, K.; Atwood, W. B.; ...

2010-05-27

We present detailed observations of the bright short-hard gamma-ray burst GRB 090510 made with the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board the Fermi observatory. GRB 090510 is the first burst detected by the LAT that shows strong evidence for a deviation from a Band spectral fitting function during the prompt emission phase. The time-integrated spectrum is fit by the sum of a Band function with E peak = 3.9 ± 0.3 MeV, which is the highest yet measured, and a hard power-law component with photon index –1.62 ± 0.03 that dominates the emission below ≈20more » keV and above ≈100 MeV. The onset of the high-energy spectral component appears to be delayed by ~0.1 s with respect to the onset of a component well fit with a single Band function. A faint GBM pulse and a LAT photon are detected 0.5 s before the main pulse. During the prompt phase, the LAT detected a photon with energy 30.5 +5.8 –2.6 GeV, the highest ever measured from a short GRB. Observation of this photon sets a minimum bulk outflow Lorentz factor, Γ≳ 1200, using simple γγ opacity arguments for this GRB at redshift z = 0.903 and a variability timescale on the order of tens of ms for the ≈100 keV-few MeV flux. Stricter high confidence estimates imply Γ ≳ 1000 and still require that the outflows powering short GRBs are at least as highly relativistic as those of long-duration GRBs. Finally, implications of the temporal behavior and power-law shape of the additional component on synchrotron/synchrotron self-Compton, external-shock synchrotron, and hadronic models are considered.« less

Transient survey rates for orphan afterglows from compact merger jets

NASA Astrophysics Data System (ADS)

Lamb, Gavin P.; Tanaka, Masaomi; Kobayashi, Shiho

2018-06-01

Orphan afterglows from short γ-ray bursts (GRBs) are potential candidates for electromagnetic (EM) counterpart searches to gravitational wave (GW) detected neutron star or neutron star black hole mergers. Various jet dynamical and structure models have been proposed that can be tested by the detection of a large sample of GW-EM counterparts. We make predictions for the expected rate of optical transients from these jet models for future survey telescopes, without a GW or GRB trigger. A sample of merger jets is generated in the redshift limits 0 ≤ z ≤ 3.0, and the expected peak r-band flux and time-scale above the Large Synoptic Survey Telescope (LSST) or Zwicky Transient Factory (ZTF) detection threshold, mr = 24.5 and 20.4, respectively, is calculated. General all-sky rates are shown for mr ≤ 26.0 and mr ≤ 21.0. The detected orphan and GRB afterglow rate depends on jet model, typically 16≲ R≲ 76 yr-1 for the LSST, and 2≲ R ≲ 8 yr-1 for ZTF. An excess in the rate of orphan afterglows for a survey to a depth of mr ≤ 26 would indicate that merger jets have a dominant low-Lorentz factor population, or the jets exhibit intrinsic jet structure. Careful filtering of transients is required to successfully identify orphan afterglows from either short- or long-GRB progenitors.

A VLA Study of High-redshift GRBs. II. The Complex Radio Afterglow of GRB 140304A: Shell Collisions and Two Reverse Shocks

NASA Astrophysics Data System (ADS)

Laskar, Tanmoy; Berger, Edo; Margutti, Raffaella; Zauderer, B. Ashley; Williams, Peter K. G.; Fong, Wen-fai; Sari, Re’em; Alexander, Kate D.; Kamble, Atish

2018-06-01

We present detailed multifrequency, multiepoch radio observations of GRB 140304A at z = 5.283 from 1 to 86 GHz and from 0.45 to 89 days. The radio and millimeter data exhibit unusual multiple spectral components, which cannot be simply explained by standard forward and reverse shock scenarios. Through detailed multiwavelength analysis spanning radio to X-rays, we constrain the forward shock parameters to E k,iso ≈ 4.9 × 1054 erg, {A}* ≈ 2.6 × 10‑2, {ε }{{e}} ≈ 2.5 × 10‑2, {ε }{{B}} ≈ 5.9 × 10‑2, p ≈ 2.6, and {θ }jet} ≈ 1.°1, yielding a beaming-corrected γ-ray and kinetic energy, {E}γ ≈ 2.3 × 1049 erg and {E}{{K}} ≈ 9.5 × 1050 erg, respectively. We model the excess radio emission as due to a combination of a late-time reverse shock (RS) launched by a shell collision, which also produces a rebrightening in the X-rays at ≈0.26 days, and either a standard RS or diffractive interstellar scintillation (ISS). Under the standard RS interpretation, we invoke consistency arguments between the forward and reverse shocks to derive a deceleration time, t dec ≈ 100 s, the ejecta Lorentz factor, Γ(t dec) ≈ 300, and a low RS magnetization, R B ≈ 0.6. Our observations highlight both the power of radio observations in capturing RS emission and thus constraining the properties of GRB ejecta and central engines and the challenge presented by ISS in conclusively identifying RS emission in GRB radio afterglows.

Predicting supernova associated to gamma-ray burst 130427a

NASA Astrophysics Data System (ADS)

Wang, Y.; Ruffini, R.; Kovacevic, M.; Bianco, C. L.; Enderli, M.; Muccino, M.; Penacchioni, A. V.; Pisani, G. B.; Rueda, J. A.

2015-07-01

Binary systems constituted by a neutron star and a massive star are not rare in the universe. The Induced Gravitational Gamma-ray Burst (IGC) paradigm interprets Gamma-ray bursts as the outcome of a neutron star that collapses into a black hole due to the accretion of the ejecta coming from its companion massive star that underwent a supernova event. GRB 130427A is one of the most luminous GRBs ever observed, of which isotropic energy exceeds 1054 erg. And it is within one of the few GRBs obtained optical, X-ray and GeV spectra simultaneously for hundreds of seconds, which provides an unique opportunity so far to understand the multi-wavelength observation within the IGC paradigm, our data analysis found low Lorentz factor blackbody emission in the Episode 3 and its X-ray light curve overlaps typical IGC Golden Sample, which comply to the IGC mechanisms. We consider these findings as clues of GRB 130427A belonging to the IGC GRBs. We predicted on GCN the emergence of a supernova on May 2, 2013, which was later successfully detected on May 13, 2013.

GRB 090227B: THE MISSING LINK BETWEEN THE GENUINE SHORT AND LONG GAMMA-RAY BURSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muccino, M.; Ruffini, R.; Bianco, C. L.

2013-02-15

The time-resolved spectral analysis of GRB 090227B, made possible by the Fermi-GBM data, allows us to identify in this source the missing link between the genuine short and long gamma-ray bursts (GRBs). Within the Fireshell model of the GRBs we predict genuine short GRBs: bursts with the same inner engine of the long bursts but endowed with a severely low value of the baryon load, B {approx}< 5 Multiplication-Sign 10{sup -5}. A first energetically predominant emission occurs at the transparency of the e {sup +} e {sup -} plasma, the Proper-GRB (P-GRB), followed by a softer emission, the extended afterglow.more » The typical separation between the two emissions is expected to be of the order of 10{sup -3}-10{sup -2} s. We identify the P-GRB of GRB 090227B in the first 96 ms of emission, where a thermal component with the temperature kT = (517 {+-} 28) keV and a flux comparable with the non-thermal part of the spectrum is observed. This non-thermal component as well as the subsequent emission, where there is no evidence for a thermal spectrum, is identified with the extended afterglow. We deduce a theoretical cosmological redshift z = 1.61 {+-} 0.14. We then derive the total energy E{sup tot}{sub e{sup +}e{sup -}}= (2.83{+-}0.15) Multiplication-Sign 10{sup 53} erg, the baryon load B = (4.13 {+-} 0.05) Multiplication-Sign 10{sup -5}, the Lorentz {Gamma} factor at transparency {Gamma}{sub tr} = (1.44 {+-} 0.01) Multiplication-Sign 10{sup 4}, and the intrinsic duration {Delta}t' {approx} 0.35 s. We also determine the average density of the circumburst medium (CBM), (n {sub CBM}) = (1.90 {+-} 0.20) Multiplication-Sign 10{sup -5} particles cm{sup -3}. There is no evidence of beaming in the system. In view of the energetics and of the baryon load of the source, as well as of the low interstellar medium and of the intrinsic timescale of the signal, we identify the GRB progenitor as a binary neutron star. From the recent progress in the theory of neutron stars, we obtain masses of the stars m {sub 1} = m {sub 2} = 1.34 M {sub Sun} and their corresponding radii R {sub 1} = R {sub 2} = 12.24 km and thickness of their crusts {approx}0.47 km, consistent with the above values of the baryon load, of the energetics and of the time duration of the event.« less

Constraining the High-Energy Emission from Gamma-Ray Bursts with Fermi

NASA Technical Reports Server (NTRS)

Gehrels, Neil; Harding, A. K.; Hays, E.; Racusin, J. L.; Sonbas, E.; Stamatikos, M.; Guirec, S.

2012-01-01

We examine 288 GRBs detected by the Fermi Gamma-ray Space Telescope's Gamma-ray Burst Monitor (GBM) that fell within the field-of-view of Fermi's Large Area Telescope (LAT) during the first 2.5 years of observations, which showed no evidence for emission above 100 MeV. We report the photon flux upper limits in the 0.1-10 GeV range during the prompt emission phase as well as for fixed 30 s and 100 s integrations starting from the trigger time for each burst. We compare these limits with the fluxes that would be expected from extrapolations of spectral fits presented in the first GBM spectral catalog and infer that roughly half of the GBM-detected bursts either require spectral breaks between the GBM and LAT energy bands or have intrinsically steeper spectra above the peak of the nuF(sub v) spectra (E(sub pk)). In order to distinguish between these two scenarios, we perform joint GBM and LAT spectral fits to the 30 brightest GBM-detected bursts and find that a majority of these bursts are indeed softer above E(sub pk) than would be inferred from fitting the GBM data alone. Approximately 20% of this spectroscopic subsample show statistically significant evidence for a cut-off in their high-energy spectra, which if assumed to be due to gamma gamma attenuation, places limits on the maximum Lorentz factor associated with the relativistic outflow producing this emission. All of these latter bursts have maximum Lorentz factor estimates that are well below the minimum Lorentz factors calculated for LAT-detected GRBs, revealing a wide distribution in the bulk Lorentz factor of GRB outflows and indicating that LAT-detected bursts may represent the high end of this distribution.

Constraining the high-energy emission from gamma-ray bursts with Fermi

DOE PAGES

Ackermann, M.; Ajello, M.; Baldini, L.; ...

2012-07-17

Here, we examine 288 gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Space Telescope's Gamma-ray Burst Monitor (GBM) that fell within the field of view of Fermi's Large Area Telescope (LAT) during the first 2.5 years of observations, which showed no evidence for emission above 100 MeV. We report the photon flux upper limits in the 0.1-10 GeV range during the prompt emission phase as well as for fixed 30 s and 100 s integrations starting from the trigger time for each burst. We also compare these limits with the fluxes that would be expected from extrapolations of spectral fitsmore » presented in the first GBM spectral catalog and infer that roughly half of the GBM-detected bursts either require spectral breaks between the GBM and LAT energy bands or have intrinsically steeper spectra above the peak of the νF ν spectra (E pk). In order to distinguish between these two scenarios, we perform joint GBM and LAT spectral fits to the 30 brightest GBM-detected bursts and find that a majority of these bursts are indeed softer above E pk than would be inferred from fitting the GBM data alone. Approximately 20% of this spectroscopic subsample show statistically significant evidence for a cutoff in their high-energy spectra, which if assumed to be due to γγ attenuation, places limits on the maximum Lorentz factor associated with the relativistic outflow producing this emission. Furthermore, all of these latter bursts have maximum Lorentz factor estimates that are well below the minimum Lorentz factors calculated for LAT-detected GRBs, revealing a wide distribution in the bulk Lorentz factor of GRB outflows and indicating that LAT-detected bursts may represent the high end of this distribution.« less

Constraining the High-energy Emission from Gamma-Ray Bursts with Fermi

NASA Astrophysics Data System (ADS)

Fermi Large Area Telescope Team; Ackermann, M.; Ajello, M.; Baldini, L.; Barbiellini, G.; Baring, M. G.; Bechtol, K.; Bellazzini, R.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bottacini, E.; Bouvier, A.; Brigida, M.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Cutini, S.; D'Ammando, F.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Drlica-Wagner, A.; Favuzzi, C.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Giroletti, M.; Glanzman, T.; Granot, J.; Grenier, I. A.; Grove, J. E.; Hadasch, D.; Hanabata, Y.; Harding, A. K.; Hays, E.; Horan, D.; Jóhannesson, G.; Kataoka, J.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Mazziotta, M. N.; McEnery, J.; McGlynn, S.; Michelson, P. F.; Mitthumsiri, W.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Naumann-Godo, M.; Norris, J. P.; Nuss, E.; Nymark, T.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Racusin, J. L.; Rainò, S.; Rando, R.; Razzaque, S.; Reimer, A.; Reimer, O.; Ritz, S.; Ryde, F.; Sgrò, C.; Siskind, E. J.; Sonbas, E.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Stawarz, Łukasz; Suson, D. J.; Takahashi, H.; Tanaka, T.; Thayer, J. G.; Thayer, J. B.; Tibaldo, L.; Tinivella, M.; Tosti, G.; Uehara, T.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vitale, V.; Waite, A. P.; Fermi Gamma-ray Burst Monitor Team; Connaughton, V.; Briggs, M. S.; Guirec, S.; Goldstein, A.; Burgess, J. M.; Bhat, P. N.; Bissaldi, E.; Camero-Arranz, A.; Fishman, J.; Fitzpatrick, G.; Foley, S.; Gruber, D.; Jenke, P.; Kippen, R. M.; Kouveliotou, C.; McBreen, S.; Meegan, C.; Paciesas, W. S.; Preece, R.; Rau, A.; Tierney, D.; van der Horst, A. J.; von Kienlin, A.; Wilson-Hodge, C.; Xiong, S.

2012-08-01

We examine 288 gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray Space Telescope's Gamma-ray Burst Monitor (GBM) that fell within the field of view of Fermi's Large Area Telescope (LAT) during the first 2.5 years of observations, which showed no evidence for emission above 100 MeV. We report the photon flux upper limits in the 0.1-10 GeV range during the prompt emission phase as well as for fixed 30 s and 100 s integrations starting from the trigger time for each burst. We compare these limits with the fluxes that would be expected from extrapolations of spectral fits presented in the first GBM spectral catalog and infer that roughly half of the GBM-detected bursts either require spectral breaks between the GBM and LAT energy bands or have intrinsically steeper spectra above the peak of the νF ν spectra (E pk). In order to distinguish between these two scenarios, we perform joint GBM and LAT spectral fits to the 30 brightest GBM-detected bursts and find that a majority of these bursts are indeed softer above E pk than would be inferred from fitting the GBM data alone. Approximately 20% of this spectroscopic subsample show statistically significant evidence for a cutoff in their high-energy spectra, which if assumed to be due to γγ attenuation, places limits on the maximum Lorentz factor associated with the relativistic outflow producing this emission. All of these latter bursts have maximum Lorentz factor estimates that are well below the minimum Lorentz factors calculated for LAT-detected GRBs, revealing a wide distribution in the bulk Lorentz factor of GRB outflows and indicating that LAT-detected bursts may represent the high end of this distribution.

Simulations of Gamma-Ray Burst Jets in a Stratified External Medium: Dynamics, Afterglow Light Curves, Jet Breaks, and Radio Calorimetry

NASA Astrophysics Data System (ADS)

De Colle, Fabio; Ramirez-Ruiz, Enrico; Granot, Jonathan; Lopez-Camara, Diego

2012-05-01

The dynamics of gamma-ray burst (GRB) jets during the afterglow phase is most reliably and accurately modeled using hydrodynamic simulations. All published simulations so far, however, have considered only a uniform external medium, while a stratified external medium is expected around long duration GRB progenitors. Here, we present simulations of the dynamics of GRB jets and the resulting afterglow emission for both uniform and stratified external media with ρextvpropr -k for k = 0, 1, 2. The simulations are performed in two dimensions using the special relativistic version of the Mezcal code. Common to all calculations is the initiation of the GRB jet as a conical wedge of half-opening angle θ0 = 0.2 whose radial profile is taken from the self-similar Blandford-McKee solution. The dynamics for stratified external media (k = 1, 2) are broadly similar to those derived for expansion into a uniform external medium (k = 0). The jet half-opening angle is observed to start increasing logarithmically with time (or radius) once the Lorentz factor Γ drops below θ-1 0. For larger k values, however, the lateral expansion is faster at early times (when Γ > θ-1 0) and slower at late times with the jet expansion becoming Newtonian and slowly approaching spherical symmetry over progressively longer timescales. We find that, contrary to analytic expectations, there is a reasonably sharp jet break in the light curve for k = 2 (a wind-like external medium), although the shape of the break is affected more by the viewing angle (for θobs <= θ0) than by the slope of the external density profile (for 0 <= k <= 2). Steeper density profiles (i.e., increasing k values) are found to produce more gradual jet breaks while larger viewing angles cause smoother and later appearing jet breaks. The counterjet becomes visible as it becomes sub-relativistic, and for k = 0 this results in a clear bump-like feature in the light curve. However, for larger k values the jet decelerates more gradually, causing only a mild flattening in the radio light curve that might be hard to discern when k = 2. Late-time radio calorimetry, which makes use of a spherical flow approximation near the non-relativistic transition, is likely to consistently overestimate the true energy by up to a factor of a few for k = 2, but likely to either overpredict or underpredict it by a smaller factor for k = 0, 1.

GRB afterglows in the nonrelativistic phase

NASA Astrophysics Data System (ADS)

Huang, Y. F.; Lu, T.

2008-10-01

When discussing the afterglows of gamma-ray bursts analytically, it is usually assumed that the external shock is always ultra-relativisitc, with the bulk Lorentz factor much larger than 1. However, we show that the deceleration of the external shock is actually very quick. The afterglow may typically enter the nonrelativistic phase in several days to teens of days, and may even enter the deep Newtonian phase in tens of days to several months. One thus should be careful in using those familiar analytical expressions that are derived only under the ultra-relativistic assumption. To explain the observed afterglows that typically last for a few weeks to several months, we need to consider the dynamics and radiation in the nonrelativisitic phase.

Distinct Involvement of the Gab1 and Grb2 Adaptor Proteins in Signal Transduction by the Related Receptor Tyrosine Kinases RON and MET

PubMed Central

Chaudhuri, Amitabha; Xie, Ming-Hong; Yang, Becky; Mahapatra, Kaushiki; Liu, Jinfeng; Marsters, Scot; Bodepudi, Sweta; Ashkenazi, Avi

2011-01-01

Although the signal transduction mechanisms of the receptor tyrosine kinase MET are well defined, less is known about its close relative RON. MET initiates intracellular signaling by autophosphorylation on specific cytoplasmic tyrosines that form docking sites for the adaptor proteins Grb2 and Gab1. Grb2 binds directly and is essential for all of the biological activities of MET. Gab1 docks either directly or indirectly via Grb2 and controls only a subset of MET functions. Because MET and RON possess similar adaptor binding sites, it was anticipated that their adaptor interactions would be conserved. Here we show that in contrast to MET, RON relies primarily on Gab1 for signal transmission. Surprisingly, disruption of the Grb2 docking site of RON or Grb2 depletion augments activity, whereas enhancement of Grb2 binding attenuates Gab1 recruitment and signaling. Hence, RON and MET differ in their adaptor interactions; furthermore, Grb2 performs a novel antagonistic role in the context of RON signaling. PMID:21784853

Variable jet properties in GRB 110721A: time resolved observations of the jet photosphere

NASA Astrophysics Data System (ADS)

Iyyani, S.; Ryde, F.; Axelsson, M.; Burgess, J. M.; Guiriec, S.; Larsson, J.; Lundman, C.; Moretti, E.; McGlynn, S.; Nymark, T.; Rosquist, K.

2013-08-01

Fermi Gamma-ray Space Telescope observations of GRB 110721A have revealed two emission components from the relativistic jet: emission from the photosphere, peaking at ˜100 keV, and a non-thermal component, which peaks at ˜1000 keV. We use the photospheric component to calculate the properties of the relativistic outflow. We find a strong evolution in the flow properties: the Lorentz factor decreases with time during the bursts from Γ ˜ 1000 to ˜150 (assuming a redshift z = 2; the values are only weakly dependent on unknown efficiency parameters). Such a decrease is contrary to the expectations from the internal shocks and the isolated magnetar birth models. Moreover, the position of the flow nozzle measured from the central engine, r0, increases by more than two orders of magnitude. Assuming a moderately magnetized outflow we estimate that r0 varies from 106 to ˜109 cm during the burst. We suggest that the maximal value reflects the size of the progenitor core. Finally, we show that these jet properties naturally explain the observed broken power-law decay of the temperature which has been reported as a characteristic for gamma-ray burst pulses.

Correlation Analysis of Prompt Emission from Gamma Ray Bursts

NASA Astrophysics Data System (ADS)

Pothapragada, Sriharsha

Prompt emission from gamma-ray bursts (GRBs) exhibits very rapid, complicated temporal and spectral evolution. This diverse variability in the light-curves reflects the complicated nature of the underlying physics, in which inter-penetrating relativistic shells in the outflow are believed to generate strong magnetic fields that vary over very small scales. We use the theory of jitter radiation to model the emission from such regions and the resulting overall prompt gamma ray emission from a series of relativistic collisionless shocks. We present simulated GRB light-curves developed as a series of "pulses" corresponding to instantaneously illuminated "thin-shell" regions emitting via the jitter radiation mechanism. The effects of various geometries, viewing angles, and bulk Lorentz factor profiles of the radiating outflow jets on the spectral features and evolution of these light-curves are explored. Our results demonstrate how an anisotropic jitter radiation pattern, in conjunction with relativistic shock kinematics, can produce certain features observed in the GRB prompt emission spectra, such as the occurrence of hard, synchrotron violating spectra, the "tracking" of observed flux with spectral parameters, and spectral softening below peak energy within individual episodes of the light curve. We highlight predictions in the light of recent advances in the observational sphere of GRBs.

AN EVOLVING STELLAR INITIAL MASS FUNCTION AND THE GAMMA-RAY BURST REDSHIFT DISTRIBUTION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, F. Y.; Dai, Z. G.

2011-02-01

Recent studies suggest that Swift gamma-ray bursts (GRBs) may not trace an ordinary star formation history (SFH). Here, we show that the GRB rate turns out to be consistent with the SFH with an evolving stellar initial mass function (IMF). We first show that the latest Swift sample of GRBs reveals an increasing evolution in the GRB rate relative to the ordinary star formation rate at high redshifts. We then assume only massive stars with masses greater than the critical value to produce GRBs and use an evolving stellar IMF suggested by Dave to fit the latest GRB redshift distribution.more » This evolving IMF would increase the relative number of massive stars, which could lead to more GRB explosions at high redshifts. We find that the evolving IMF can well reproduce the observed redshift distribution of Swift GRBs.« less

Electron and ion acceleration in relativistic shocks with applications to GRB afterglows

NASA Astrophysics Data System (ADS)

Warren, Donald C.; Ellison, Donald C.; Bykov, Andrei M.; Lee, Shiu-Hang

2015-09-01

We have modelled the simultaneous first-order Fermi shock acceleration of protons, electrons, and helium nuclei by relativistic shocks. By parametrizing the particle diffusion, our steady-state Monte Carlo simulation allows us to follow particles from particle injection at non-relativistic thermal energies to above PeV energies, including the non-linear smoothing of the shock structure due to cosmic ray (CR) backpressure. We observe the mass-to-charge (A/Z) enhancement effect believed to occur in efficient Fermi acceleration in non-relativistic shocks and we parametrize the transfer of ion energy to electrons seen in particle-in-cell (PIC) simulations. For a given set of environmental and model parameters, the Monte Carlo simulation determines the absolute normalization of the particle distributions and the resulting synchrotron, inverse Compton, and pion-decay emission in a largely self-consistent manner. The simulation is flexible and can be readily used with a wide range of parameters typical of γ-ray burst (GRB) afterglows. We describe some preliminary results for photon emission from shocks of different Lorentz factors and outline how the Monte Carlo simulation can be generalized and coupled to hydrodynamic simulations of GRB blast waves. We assume Bohm diffusion for simplicity but emphasize that the non-linear effects we describe stem mainly from an extended shock precursor where higher energy particles diffuse further upstream. Quantitative differences will occur with different diffusion models, particularly for the maximum CR energy and photon emission, but these non-linear effects should be qualitatively similar as long as the scattering mean-free path is an increasing function of momentum.

CONSTRAINING THE GRB-MAGNETAR MODEL BY MEANS OF THE GALACTIC PULSAR POPULATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rea, N.; Gullón, M.; Pons, J. A.

2015-11-10

A large fraction of Gamma-ray bursts (GRBs) displays an X-ray plateau phase within <10{sup 5} s from the prompt emission, proposed to be powered by the spin-down energy of a rapidly spinning newly born magnetar. In this work we use the properties of the Galactic neutron star population to constrain the GRB-magnetar scenario. We re-analyze the X-ray plateaus of all Swift GRBs with known redshift, between 2005 January and 2014 August. From the derived initial magnetic field distribution for the possible magnetars left behind by the GRBs, we study the evolution and properties of a simulated GRB-magnetar population using numericalmore » simulations of magnetic field evolution, coupled with Monte Carlo simulations of Pulsar Population Synthesis in our Galaxy. We find that if the GRB X-ray plateaus are powered by the rotational energy of a newly formed magnetar, the current observational properties of the Galactic magnetar population are not compatible with being formed within the GRB scenario (regardless of the GRB type or rate at z = 0). Direct consequences would be that we should allow the existence of magnetars and “super-magnetars” having different progenitors, and that Type Ib/c SNe related to Long GRBs form systematically neutron stars with higher initial magnetic fields. We put an upper limit of ≤16 “super-magnetars” formed by a GRB in our Galaxy in the past Myr (at 99% c.l.). This limit is somewhat smaller than what is roughly expected from Long GRB rates, although the very large uncertainties do not allow us to draw strong conclusion in this respect.« less

The Discovery of an Evolving Dust Scattered X-ray Halo Around GRB 031203

NASA Technical Reports Server (NTRS)

Vaughan, S.; Willingale, R.; OBrien, P. T.; Osborne, J. P.; Reeves, J. N.; Levan, A. J.; Watson, M. G.; Tedds, J. A.; Watson, D.; Santos-Lleo, M.

2003-01-01

We report the first detection of a time-dependent, dust-scattered X-ray halo around a gamma-ray burst. GRB3 031203 was observed by XMM-Newton starting six hours after the burst. The halo appeared as concentric ring-like structures centered on the GRB location. The radii of these structures increased with time as t(sup 1/2), consistent with small-angle X-ray scattering caused by a large column of dust along the line of sight to a cosmologically distant GRB. The rings are due to dust concentrated in two distinct slabs in the Galaxy located at distances of 880 and 1390 pc, consistent with known Galactic features. The halo brightness implies an initial soft X-ray pulse consistent with the observed GRB.

Did a Gamma-Ray Burst Initiate the Late Ordovician Mass Extinction?

NASA Technical Reports Server (NTRS)

Melott, A. L.; Lieberman, B. S.; Laird, C. M.; Martin, L. D.; Medvedov, M. V.; Thomas, B. C.; Cannizzo, J. K.; Gehrels, N.; Jackman, C. H.

2004-01-01

Gamma-ray bursts (hereafter GRB) produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average several times per billion years. At leastfive times in the history of lfe, the Earth experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and GRB may also have contributed. The late Ordovician mass extinction approximately 440 million years ago may be at least partly the result of a GRB. Due to severe depletion of the ozone layer, intense solar ultraviolet radiation is expected to result from a nearby GRB, and some of the patterns of extinction and survivorship at this time may be attributable to elevated levels of UV radiation reaching the Earth. In addition a GRB could trigger the global cooling which occurs at the end of the Ordovician period that follows an interval of relatively warm climate. Intense rapid cooling and glaciation at that time, previously identijied as the probable cause of this mass extinction, may have resultedfiom a GRB.

Lorentz violations in multifractal spacetimes

NASA Astrophysics Data System (ADS)

Calcagni, Gianluca

2017-05-01

Using the recent observation of gravitational waves (GW) produced by a black-hole merger, we place a lower bound on the energy above which a multifractal spacetime would display an anomalous geometry and, in particular, violations of Lorentz invariance. In the so-called multifractional theory with q-derivatives, we show that the deformation of dispersion relations is much stronger than in generic quantum-gravity approaches (including loop quantum gravity) and, contrary to the latter, present observations on GWs can place very strong bounds on the characteristic scales at which spacetime deviates from standard Minkowski. The energy at which multifractal effects should become apparent is E_{*}>10^{14} {GeV} (thus improving previous bounds by 12 orders of magnitude) when the exponents in the measure are fixed to their central value 1 / 2. We also estimate, for the first time, the effect of logarithmic oscillations in the measure (corresponding to a discrete spacetime structure) and find that they do not change much the bounds obtained in their absence, unless the amplitude of the oscillations is fine tuned. This feature, unavailable in known quantum-gravity scenarios, may help the theory to avoid being ruled out by gamma-ray burst (GRB) observations, for which E_{*}> 10^{17} {GeV} or greater.

Studies on High Energy Radiation Mechanisms and Gamma-Ray Burst Prompt Emissions

NASA Astrophysics Data System (ADS)

Zhang, B.

2014-07-01

Gamma-Ray Bursts (GRBs) are the most violent high-energy explosion in the universe. They are randomly happened, pulse-like phenomena with short durations. Since its discovery in 1960's by Vela satellite, GRBs have become a hot topic for astrophysical research. In 1997 the BeppoSAX satellite discovered afterglows of GRBs, and then helped to measure GRB redshifts. Thus it was found that GRBs are the events occurred at cosmological distances. Now it is widely accepted that the long bursts with durations longer than 2 s are from the collapsing massive stars, while the short bursts with durations less than 2 s are results of the merging compact binaries. By studying GRBs, the physical processes in ultrarelativistic and very high energy conditions can be investigated, and the researches on other fields, including constraining the cosmological models, can also get helped. The goal of this thesis is to present some discussions on possible radiation mechanisms and prompt light curves of GRBs. Since radiation mechanisms and prompt emissions are related to GRB central engines directly, studying these topics can help us to get a better understanding of some properties of the central engine. In Chapter 1, we review the discovery and observations of GRBs, presenting major achievements from major GRB-monitoring satellites including Compton Gamma-ray Observatory, BeppoSAX satellite, Swift satellite, as well as the latest Fermi Gamma-ray Space Telescope. The multi-wavelength properties of prompt emission as well as afterglows of GRBs are also summarized in Chapter 1. In Chapter 2 the current GRB standard model is presented. According to standard model, a fireball is ejected by the central engine. The internal shock is produced by collisions between various shells with different velocities inside the fireball. The directional kinetic energy of the fireball is then converted to internal energy, and finally the non-thermal radiation (the prompt emission) is produced by internal shocks. And the interaction between the fireball and the outer medium gives rise to external forward and reverse shocks, producing the observed afterglow. In the framework of standard model, we introduce the properties of the fireball, the evolution of shocks, some possible radiation mechanisms, as well as some post-standard effects. Also we present a brief introduction of central engines. And since the internal shock model for prompt emission has some problems hard to be solved, we also introduce some possible alternatives, including the electromagnetic model, the turbulent model, as well as the Internal-Collision-induced Magnetic Reconnection and Turbulence (ICMART) model. In Chapter 3, we present the spectrum of synchro-curvature self-Compton (SCSC) radiation of relativistic electrons with a power-law distribution of Lorentz factors. Synchro-curvature radiation from relativistic electrons moving around curved magnetic field lines and its self-Compton radiation are possible radiation mechanisms in the GRB enviroment. We find that the resulting SCSC spectrum is significantly different from that of either synchrotron self-Compton or curvature self-Compton radiation if both the curvature radius of the magnetic field and the cyclotron radius of the electrons are within some proper ranges. The effects of electrons' cooling and drifting, the low-energy self absorption in seed spectra, and the Klein-Nishina cutoff are also discussed, in order to get an accurate picture. We take GRBs as our example environment for discussions. The results would be considered as a universal approach of the self-Compton emission of relativistic electrons moving in curved magnetic fields, and thus could be applied to many astrophysical phenomena, including active galactic nuclei (AGNs), pulsars, as well as GRBs. In Chapter 4, we simulate the prompt emission light curves of GRBs within the framework of the ICMART model. This model is applied to GRBs with a moderately-high magnetization parameter σ in the emission region. We show that this model can produce highly variable light curves with both fast and slow components. The rapid variability is caused by many locally Doppler-boosted mini-emitters due to turbulent magnetic reconnection in a moderately-high-σ ejecta. The run-away growth and subsequent depletion of these mini-emitters as a function of time define a broad slow component for each ICMART event. A GRB light curve is usually composed of multiple ICMART events fundamentally driven by the erratic GRB central engine activity. Allowing variations of model parameters, including initial Lorentz factor, orientation and size distributions of reconnection regions, jet opening angle, radius of emission region, as well as observing energy band, one is able to reproduce a variety of light curves and the power density spectra (PDS) as observed. We also discuss the effects of these parameters on PDS . Finally in Chapter 5 we present our discussions, and list some remaining problems to be solved, as well as observing instruments to be commissioned in the future. We also present calculations of synchro-curvature radiation in Appendix A, and some discussions on ICMART model in Appendix B.

Affinity chromatography for purification of the modular protein growth factor receptor-bound protein 2 and development of a screening test for growth factor receptor-bound protein 2 Src homology 3 domain inhibitor using peroxidase-linked ligand.

PubMed

Gril, B; Liu, W Q; Lenoir, C; Garbay, C; Vidal, M

2006-04-01

Growth factor receptor-bound protein 2 (Grb2) is an adapter protein involved in the Ras-dependent signaling pathway that plays an important role in human cancers initiated by oncogenic receptors. Grb2 is constituted by one Src homology 2 domain surrounded by two SH3 domains, and the inhibition of the interactions produced by these domains could provide an antitumor approach. In evaluating chemical libraries, to search for potential Grb2 inhibitors, it was necessary to elaborate a rapid test for their screening. We have developed, first, a batch method based on the use of an affinity column bearing a Grb2-SH3 peptide ligand to isolate highly purified Grb2. We subsequently describe a very rapid 96-well screening of inhibitors based on a simple competition between purified Grb2 and a peroxidase-coupled proline-rich peptide.

Kinematic arguments against single relativistic shell models for GRBs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fenimore, E.E.; Ramirez, E.; Sumner, M.C.

1997-09-01

Two main types of models have been suggested to explain the long durations and multiple peaks of Gamma Ray Bursts (GRBs). In one, there is a very quick release of energy at a central site resulting in a single relativistic shell that produces peaks in the time history through its interactions with the ambient material. In the other, the central site sporadically releases energy over hundreds of seconds forming a peak with each burst of energy. The authors show that the average envelope of emission and the presence of gaps in GRBs are inconsistent with a single relativistic shell. Theymore » estimate that the maximum fraction of a single shell that can produce gamma-rays in a GRB with multiple peaks is 10{sup {minus}3}, implying that single relativistic shells require 10{sup 3} times more energy than previously thought. They conclude that either the central site of a GRB must produce {approx}10{sup 51} erg/s{sup {minus}1} for hundreds of seconds, or the relativistic shell must have structure on a scales the order of {radical}{epsilon}{Gamma}{sup {minus}1}, where {Gamma} is the bulk Lorentz factor ({approximately}10{sup 2} to 10{sup 3}) and {epsilon} is the efficiency.« less

Firework Model: Time Dependent Spectral Evolution of GRB

NASA Astrophysics Data System (ADS)

Barbiellini, Guido; Longo, Francesco; Ghirlanda, G.; Celotti, A.; Bosnjak, Z.

2004-09-01

The energetics of the long duration GRB phenomenon is compared with models of a rotating BH in a strong magnetic field generated by an accreting torus. The GRB energy emission is attributed to magnetic field vacuum breakdown that gives origin to a e +/- fireball. Its subsequent evolution is hypothesized in analogy with the in-flight decay of an elementary particle. An anisotropy in the fireball propagation is thus naturally produced. The recent discovery in some GRB of an initial phase characterized by a thermal spectrum could be interpreted as the photon emission of the fireball photosphere when it becomes transparent. In particular, the temporal evolution of the emission can be explained as the effect of a radiative deceleration of the out-moving ejecta.

ALMA and GMRT Constraints on the Off-axis Gamma-Ray Burst 170817A from the Binary Neutron Star Merger GW170817

NASA Astrophysics Data System (ADS)

Kim, S.; Schulze, S.; Resmi, L.; González-López, J.; Higgins, A. B.; Ishwara-Chandra, C. H.; Bauer, F. E.; de Gregorio-Monsalvo, I.; De Pasquale, M.; de Ugarte Postigo, A.; Kann, D. A.; Martín, S.; Oates, S. R.; Starling, R. L. C.; Tanvir, N. R.; Buchner, J.; Campana, S.; Cano, Z.; Covino, S.; Fruchter, A. S.; Fynbo, J. P. U.; Hartmann, D. H.; Hjorth, J.; Jakobsson, P.; Levan, A. J.; Malesani, D.; Michałowski, M. J.; Milvang-Jensen, B.; Misra, K.; O’Brien, P. T.; Sánchez-Ramírez, R.; Thöne, C. C.; Watson, D. J.; Wiersema, K.

2017-12-01

Binary neutron-star mergers (BNSMs) are among the most readily detectable gravitational-wave (GW) sources with the Laser Interferometer Gravitational-wave Observatory (LIGO). They are also thought to produce short γ-ray bursts (SGRBs) and kilonovae that are powered by r-process nuclei. Detecting these phenomena simultaneously would provide an unprecedented view of the physics during and after the merger of two compact objects. Such a Rosetta Stone event was detected by LIGO/Virgo on 2017 August 17 at a distance of ∼44 Mpc. We monitored the position of the BNSM with Atacama Large Millimeter/submillimeter Array (ALMA) at 338.5 GHz and the Giant Metrewave Radio Telescope (GMRT) at 1.4 GHz, from 1.4 to 44 days after the merger. Our observations rule out any afterglow more luminous than 3× {10}26 {erg} {{{s}}}-1 {{Hz}}-1 in these bands, probing >2–4 dex fainter than previous SGRB limits. We match these limits, in conjunction with public data announcing the appearance of X-ray and radio emission in the weeks after the GW event, to templates of off-axis afterglows. Our broadband modeling suggests that GW170817 was accompanied by an SGRB and that the γ-ray burst (GRB) jet, powered by {E}{AG,{iso}}∼ {10}50 erg, had a half-opening angle of ∼ 20^\\circ , and was misaligned by ∼ 41^\\circ from our line of sight. The data are also consistent with a more collimated jet: {E}{AG,{iso}}∼ {10}51 erg, {θ }1/2,{jet}∼ 5^\\circ ,{θ }{obs}∼ 17^\\circ . This is the most conclusive detection of an off-axis GRB afterglow and the first associated with a BNSM-GW event to date. We use the viewing angle estimates to infer the initial bulk Lorentz factor and true energy release of the burst.

OT1_mhuang01_1: GRB Afterglow Photometry with Herschel Infrared Cameras

NASA Astrophysics Data System (ADS)

Huang, M.

2010-07-01

GRB Afterglow Photometry with Herschel Infrared Cameras (GRAPHICS) Gamma-ray bursts (GRBs) are the most luminous explosions in the universe. It has been difficult to obtain a full spectral picture of the phenomena in the short period when GRBs become ``alive'', i.e. when they generate bursts in Gamma-ray and produce afterglows in other wavelengths. Between NIR (12micron) and submillimeter (850micron) there lies nearly two orders of magnitude of spectral range where GRB afterglows have never been detected. Herschel is unique in its cutting edge sensitivity, efficiency, and readiness in FIR observations, and is capable of detecting GRB afterglows. Observing GRB afterglows with Herschel would greatly enrich our understanding of GRB physics and conditions of the Universe in early epochs. We propose Target of Opportunity studies using the SPIRE and PACS instruments of Herschel to observe 3 bright GRB afterglows, each within a few hours to a few tens of days after burst. We will make follow-up observations after the initial one to photometrically measure GRB light curves and IR SEDs. We will make ground optical observations to compliment Herschel data, and have the the GRB community informed. Observing the forward shock peak in the FIR light curve and compare it (both the flux and time) with those in the optical and radio bands would give a unambiguous test to the fireball model, and offer a direct measurement of the density profile of the circumburst material. Catching the short-lived reverse shock emission and measure its magnitude would lead to constraints on some important parameters of the GRB ejecta and address the unknown composition of GRBs, baryonic vs. magnetic.

Photospheric Emission from Stratified Jets

NASA Astrophysics Data System (ADS)

Ito, Hirotaka; Nagataki, Shigehiro; Ono, Masaomi; Lee, Shiu-Hang; Mao, Jirong; Yamada, Shoichi; Pe'er, Asaf; Mizuta, Akira; Harikae, Seiji

2013-11-01

We explore photospheric emissions from stratified two-component jets, wherein a highly relativistic spine outflow is surrounded by a wider and less relativistic sheath outflow. Thermal photons are injected in regions of high optical depth and propagated until the photons escape at the photosphere. Because of the presence of shear in velocity (Lorentz factor) at the boundary of the spine and sheath region, a fraction of the injected photons are accelerated using a Fermi-like acceleration mechanism such that a high-energy power-law tail is formed in the resultant spectrum. We show, in particular, that if a velocity shear with a considerable variance in the bulk Lorentz factor is present, the high-energy part of observed gamma-ray bursts (GRBs) photon spectrum can be explained by this photon acceleration mechanism. We also show that the accelerated photons might also account for the origin of the extra-hard power-law component above the bump of the thermal-like peak seen in some peculiar bursts (e.g., GRB 090510, 090902B, 090926A). We demonstrate that time-integrated spectra can also reproduce the low-energy spectrum of GRBs consistently using a multi-temperature effect when time evolution of the outflow is considered. Last, we show that the empirical E p-L p relation can be explained by differences in the outflow properties of individual sources.

Marginally fast cooling synchrotron models for prompt GRBs

NASA Astrophysics Data System (ADS)

Beniamini, Paz; Barniol Duran, Rodolfo; Giannios, Dimitrios

2018-05-01

Previous studies have considered synchrotron as the emission mechanism for prompt gamma-ray bursts (GRBs). These works have shown that the electrons must cool on a time-scale comparable to the dynamic time at the source in order to satisfy spectral constraints while maintaining high radiative efficiency. We focus on conditions where synchrotron cooling is balanced by a continuous source of heating, and in which these constraints are naturally satisfied. Assuming that a majority of the electrons in the emitting region are contributing to the observed peak, we find that the energy per electron has to be E ≳ 20 GeV and that the Lorentz factor of the emitting material has to be very large 103 ≲ Γem ≲ 104, well in excess of the bulk Lorentz factor of the jet inferred from GRB afterglows. A number of independent constraints then indicate that the emitters must be moving relativistically, with Γ΄ ≈ 10, relative to the bulk frame of the jet and that the jet must be highly magnetized upstream of the emission region, σup ≳ 30. The emission radius is also strongly constrained in this model to R ≳ 1016 cm. These values are consistent with magnetic jet models where the dissipation is driven by magnetic reconnection that takes place far away from the base of the jet.

GRB 011121: A Collimated Outflow into Wind-Blown Surroundings

NASA Technical Reports Server (NTRS)

Greiner, J.; Klose, S.; Salvato, M.; Zeh, A.; Schwarz, R.; Hartmann, D. H.; Masetti, N.; Stecklum, B.; Lamer, G.; Lodieu, N.;

An infrared flash contemporaneous with the gamma-rays of GRB 041219a.

PubMed

Blake, C H; Bloom, J S; Starr, D L; Falco, E E; Skrutskie, M; Fenimore, E E; Duchêne, G; Szentgyorgyi, A; Hornstein, S; Prochaska, J X; McCabe, C; Ghez, A; Konopacky, Q; Stapelfeldt, K; Hurley, K; Campbell, R; Kassis, M; Chaffee, F; Gehrels, N; Barthelmy, S; Cummings, J R; Hullinger, D; Krimm, H A; Markwardt, C B; Palmer, D; Parsons, A; McLean, K; Tueller, J

2005-05-12

The explosion that results in a cosmic gamma-ray burst (GRB) is thought to produce emission from two physical processes: the central engine gives rise to the high-energy emission of the burst through internal shocking, and the subsequent interaction of the flow with the external environment produces long-wavelength afterglows. Although observations of afterglows continue to refine our understanding of GRB progenitors and relativistic shocks, gamma-ray observations alone have not yielded a clear picture of the origin of the prompt emission nor details of the central engine. Only one concurrent visible-light transient has been found and it was associated with emission from an external shock. Here we report the discovery of infrared emission contemporaneous with a GRB, beginning 7.2 minutes after the onset of GRB 041219a (ref. 8). We acquired 21 images during the active phase of the burst, yielding early multi-colour observations. Our analysis of the initial infrared pulse suggests an origin consistent with internal shocks.

Early optical polarization of a gamma-ray burst afterglow.

PubMed

Mundell, Carole G; Steele, Iain A; Smith, Robert J; Kobayashi, Shiho; Melandri, Andrea; Guidorzi, Cristiano; Gomboc, Andreja; Mottram, Chris J; Clarke, David; Monfardini, Alessandro; Carter, David; Bersier, David

2007-03-30

We report the optical polarization of a gamma-ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma-rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2sigma) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region.

CONSTRAINTS ON THE SYNCHROTRON EMISSION MECHANISM IN GAMMA-RAY BURSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beniamini, Paz; Piran, Tsvi, E-mail: paz.beniamini@mail.huji.ac.il, E-mail: tsvi.piran@mail.huji.ac.il

2013-05-20

We reexamine the general synchrotron model for gamma-ray bursts' (GRBs') prompt emission and determine the regime in the parameter phase space in which it is viable. We characterize a typical GRB pulse in terms of its peak energy, peak flux, and duration and use the latest Fermi observations to constrain the high-energy part of the spectrum. We solve for the intrinsic parameters at the emission region and find the possible parameter phase space for synchrotron emission. Our approach is general and it does not depend on a specific energy dissipation mechanism. Reasonable synchrotron solutions are found with energy ratios ofmore » 10{sup -4} < {epsilon}{sub B}/{epsilon}{sub e} < 10, bulk Lorentz factor values of 300 < {Gamma} < 3000, typical electrons' Lorentz factor values of 3 Multiplication-Sign 10{sup 3} < {gamma}{sub e} < 10{sup 5}, and emission radii of the order 10{sup 15} cm < R < 10{sup 17} cm. Most remarkable among those are the rather large values of the emission radius and the electron's Lorentz factor. We find that soft (with peak energy less than 100 keV) but luminous (isotropic luminosity of 1.5 Multiplication-Sign 10{sup 53}) pulses are inefficient. This may explain the lack of strong soft bursts. In cases when most of the energy is carried out by the kinetic energy of the flow, such as in the internal shocks, the synchrotron solution requires that only a small fraction of the electrons are accelerated to relativistic velocities by the shocks. We show that future observations of very high energy photons from GRBs by CTA could possibly determine all parameters of the synchrotron model or rule it out altogether.« less

CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM GRB 130427A

DOE PAGES

Aliu, E.; Aune, T.; Barnacka, A.; ...

2014-10-10

In this study, prompt emission from the very fluent and nearby (z = 0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of this GRB, it is exceptional due to the extremely long-lived high-energy (100 MeV to 100 GeV) gamma-ray emission, which was detected by the Large Area Telescope on the Fermi Gamma-Ray Space Telescope for ~70 ks after the initial burst. The persistent, hard-spectrum, high-energy emission suggests that the highest-energy gamma rays may have been produced via synchrotron self-Compton processes though there is alsomore » evidence that the high-energy emission may instead be an extension of the synchrotron spectrum. VERITAS, a ground-based imaging atmospheric Cherenkov telescope array, began follow-up observations of GRB 130427A ~71 ks (~20 hr) after the onset of the burst. The GRB was not detected with VERITAS; however, the high elevation of the observations, coupled with the low redshift of the GRB, make VERITAS a very sensitive probe of the emission from GRB 130427A for E > 100 GeV. In conclusion, the non-detection and consequent upper limit derived place constraints on the synchrotron self-Compton model of high-energy gamma-ray emission from this burst.« less

High-energy non-thermal and thermal emission from GRB 141207A detected by Fermi

DOE PAGES

Arimoto, Makoto; Asano, Katsuaki; Ohno, Masanori; ...

2016-12-13

A bright long gamma-ray burst GRB 141207A was observed by the Fermi Gamma-ray Space Telescope and detected by both instruments onboard. The observations show that the spectrum in the prompt phase is not well described by the canonical empirical Band function alone, and that an additional power-law component is needed. In the early phase of the prompt emission, a modified blackbody with a hard low-energy photon index (α = +0.2 to +0.4) is detected, which suggests a photospheric origin. In a finely time-resolved analysis, the spectra are also well fitted by the modified blackbody combined with a power-law function. Heremore » we discuss the physical parameters of the photosphere such as the bulk Lorentz factor of the relativistic flow and the radius. We also discuss the physical origin of the extra power-law component observed during the prompt phase in the context of different models such as leptonic and hadronic scenarios in the internal shock regime and synchrotron emission in the external forward shock. In the afterglow phase, the temporal and spectral behaviors of the temporally extended high-energy emission and the fading X-ray emission detected by the X-Ray Telescope on-board Swift are consistent with synchrotron emission in a radiative external forward shock.« less

Hadronic Origin of Prompt High-energy Emission of Gamma-ray Bursts Revisited: In the Case of a Limited Maximum Proton Energy

NASA Astrophysics Data System (ADS)

Wang, Kai; Liu, Ruo-Yu; Dai, Zi-Gao; Asano, Katsuaki

2018-04-01

The high-energy (>100 MeV) emission observed by the Fermi Large Area Telescope during the prompt phase of some luminous gamma-ray bursts (GRBs) could arise from the cascade induced by interactions between accelerated protons and the radiation field of GRBs. The photomeson process, which is usually suggested to operate in such a hadronic explanation, requires a rather high proton energy (>1017 eV) for an efficient interaction. However, whether GRBs can accelerate protons to such a high energy is far from guaranteed, although they have been suggested as the candidate source for ultrahigh-energy cosmic rays. In this work, we revisit the hadronic model for the prompt high-energy emission of GRBs with a smaller maximum proton energy than the usually adopted value estimated from the Bohm condition. In this case, the Bethe–Heitler pair production process becomes comparably important or even dominates over the photomeson process. We show that with a relatively low maximum proton energy with a Lorentz factor of 105 in the comoving frame, the cascade emission can still reproduce various types of high-energy spectra of GRBs. For most GRBs without high-energy emission detected, the maximum proton energy could be even lower and relax the constraints on the parameters of the GRB jet resulting from the nondetection of GRB neutrinos by IceCube.

Structure of gamma-ray burst jets: intrinsic versus apparent properties

NASA Astrophysics Data System (ADS)

Salafia, O. S.; Ghisellini, G.; Pescalli, A.; Ghirlanda, G.; Nappo, F.

2015-07-01

With this paper we introduce the concept of apparent structure of a gamma-ray burst (GRB) jet, as opposed to its intrinsic structure. The latter is customarily defined specifying the functions ɛ(θ) (the energy emitted per jet unit solid angle) and Γ(θ) (the Lorentz factor of the emitting material); the apparent structure is instead defined by us as the isotropic equivalent energy Eiso(θv) as a function of the viewing angle θv. We show how to predict the apparent structure of a jet given its intrinsic structure. We find that a Gaussian intrinsic structure yields a power-law apparent structure: this opens a new viewpoint on the Gaussian (which can be understood as a proxy for a realistic narrow, well-collimated jet structure) as a possible candidate for a quasi-universal GRB jet structure. We show that such a model (a) is consistent with recent constraints on the observed luminosity function of GRBs; (b) implies fewer orphan afterglows with respect to the standard uniform model; (c) can break out the progenitor star (in the collapsar scenario) without wasting an unreasonable amount of energy; (d) is compatible with the explanation of the Amati correlation as a viewing angle effect; (e) can be very standard in energy content, and still yield a very wide range of observed isotropic equivalent energies.

Naked-eye optical flash from gamma-ray burst 080319B: Tracing the decaying neutrons in the outflow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan Yizhong; Zhang Bing; Wei Daming

For an unsteady baryonic gamma-ray burst (GRB) outflow, the fast and slow proton shells collide with each other and produce energetic soft gamma-ray emission. If the outflow has a significant neutron component, the ultrarelativistic neutrons initially expand freely until decaying at a larger radius. The late-time proton shells ejected from the GRB central engine, after powering the regular internal shocks, will sweep these {beta}-decay products and give rise to very bright UV/optical emission. The naked-eye optical flash from GRB 080319B, an energetic explosion in the distant Universe, can be well explained in this way.

Relativistic Shear Flow between Electron-Ion and Electron-Positron Plasmas and Astrophysical Applications

NASA Astrophysics Data System (ADS)

Liang, Edison; Fu, Wen; Böttcher, Markus

2017-10-01

We present particle-in-cell simulation results of relativistic shear boundary layers between electron-ion and electron-positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron-positron spine surrounded by a slow-moving or stationary electron-ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. This is in stark contrast to the case of pure electron-ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.

Relativistic Shear Flow between Electron–Ion and Electron–Positron Plasmas and Astrophysical Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Edison; Fu, Wen; Böttcher, Markus

We present particle-in-cell simulation results of relativistic shear boundary layers between electron–ion and electron–positron plasmas and discuss their potential applications to astrophysics. Specifically, we find that in the case of a fast electron–positron spine surrounded by a slow-moving or stationary electron–ion sheath, lepton acceleration proceeds in a highly anisotropic manner due to electromagnetic fields created at the shear interface. While the highest-energy leptons still produce a beaming pattern (as seen in the quasi-stationary frame of the sheath) of order 1/Γ, where Γ is the bulk Lorentz factor of the spine, for lower-energy particles, the beaming is much less pronounced. Thismore » is in stark contrast to the case of pure electron–ion shear layers, in which anisotropic particle acceleration leads to significantly narrower beaming patterns than 1/Γ for the highest-energy particles. In either case, shear-layer acceleration is expected to produce strongly angle-dependent lepton (hence, emanating radiation) spectra, with a significantly harder spectrum in the forward direction than viewed from larger off-axis angles, much beyond the regular Doppler boosting effect from a co-moving isotropic lepton distribution. This may solve the problem of the need for high (and apparently arbitrarily chosen) minimum Lorentz factors of radiating electrons, often plaguing current blazar and GRB jet modeling efforts.« less

Early afterglows in wind environments revisited

NASA Astrophysics Data System (ADS)

Zou, Y. C.; Wu, X. F.; Dai, Z. G.

2005-10-01

When a cold shell sweeps up the ambient medium, a forward shock and a reverse shock will form. We analyse the reverse-forward shocks in a wind environment, including their dynamics and emission. An early afterglow is emitted from the shocked shell, e.g. an optical flash may emerge. The reverse shock behaves differently in two approximations: the relativistic and Newtonian cases, which depend on the parameters, e.g. the initial Lorentz factor of the ejecta. If the initial Lorentz factor is much less than 114E1/453Δ-1/40,12A-1/4*,-1, the early reverse shock is Newtonian. This may take place for the wider of a two-component jet, an orphan afterglow caused by a low initial Lorentz factor and so on. The synchrotron self-absorption effect is significant especially for the Newtonian reverse shock case, as the absorption frequency νa is larger than the cooling frequency νc and the minimum synchrotron frequency νm for typical parameters. For the optical to X-ray band, the flux is nearly unchanged with time during the early period, which may be a diagnostic for the low initial Lorentz factor of the ejecta in a wind environment. We also investigate the early light curves with different wind densities and compare them with those in the interstellar medium model.

Implications of Lag-Luminosity Relationship for Unified GRB Paradigms

NASA Technical Reports Server (NTRS)

Norris, J. P.; White, Nicholas E. (Technical Monitor)

2002-01-01

Spectral lags (tau(sub lag)) are deduced for 1437 long (T(sub 90) greater than 2 s) BATSE gamma-ray bursts (GRBs) with peak flux F(sub p) greater than 0.25 photons cm(sup -2)/s, near to the BATSE trigger threshold. The lags are modeled to approximate the observed distribution in the F(sub p)-T(sub lag) plane, realizing a noise-free representation. Assuming a two-branch lag-luminosity relationship, the lags are self-consistently corrected for cosmological effects to yield distributions in luminosity, distance, and redshift. The results have several consequences for GRB populations and for unified gamma-ray/afterglow scenarios which would account for afterglow break times and gamma-ray spectral evolution in terms of jet opening angle, viewing angle, or a profiled jet with variable Lorentz factor: A component of the burst sample is identified - those with few, wide pulses, lags of a few tenths to several seconds, and soft spectra - whose Log[N]-Log[F(sub p)] distribution approximates a -3/2 power-law, suggesting homogeneity and thus relatively nearby sources. The proportion of these long-lag bursts increases from negligible among bright BATSE bursts to approx. 50% at trigger threshold. Bursts with very long lags, approx. 1-2 less than tau(sub lag) (S) less than 10, show a tendency to concentrate near the Supergalactic Plane with a quadrupole moment of approx. -0.10 +/- 0.04. GRB 980425 (SN 1998bw) is a member of this subsample of approx. 90 bursts with estimated distances less than 100 Mpc. The frequency of the observed ultra-low luminosity bursts is approx. 1/4 that of SNe Ib/c within the same volume. If truly nearby, the core-collapse events associated with these GRBs might produce gravitational radiation detectable by LIGO-II. Such nearby bursts might also help explain flattening of the cosmic ray spectrum at ultra-high energies, as observed by AGASA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wei, Jun-Jie; Wu, Xue-Feng; Gao, He

Five TeV neutrino events weakly correlated with five gamma-ray bursts (GRBs) were detected recently by IceCube. This work is an attempt to show that if the GRB identifications are verified, the observed time delays between the TeV neutrinos and gamma-ray photons from GRBs provide attractive candidates for testing fundamental physics with high accuracy. Based on the assumed associations between the TeV neutrinos and GRBs, we find that the limiting velocity of the neutrinos is equal to that of photons to an accuracy of ∼ 1.9 × 10{sup -15} – 2.5 × 10{sup -18}, which is about 10{sup 4} – 10{supmore » 7} times better than the constraint obtained with the neutrino possibly from a blazar flare. In addition, we set the most stringent limits up to date on the energy scale of quantum gravity for both the linear and quadratic violations of Lorentz invariance, namely E {sub QG,} {sub 1} > 6.3 × 10{sup 18} – 1.5 × 10{sup 21} GeV and E {sub QG,} {sub 2} > 2.0 × 10{sup 11} – 4.2 × 10{sup 12} GeV, which are essentially as good as or are an improvement of one order of magnitude over the results previously obtained by the GeV photons of GRB 090510 and the PeV neutrino from a blazar flare. Assuming that the Shapiro time delay is caused by the gravitational potential of the Laniakea supercluster of galaxies, we also place the tightest limits to date on Einstein's weak equivalence principle through the relative differential variations of the parameterized post-Newtonian parameter γ values for two different species of particles (i.e., neutrinos and photons), yielding Δγ ∼ 10{sup -11} – 10{sup -13}. However, it should be emphasized again that these limits here obtained are at best forecast of what could be achieved if the GRB/neutrino correlations would be finally confirmed.« less

Phosphorylation of tyrosine 720 in the platelet-derived growth factor alpha receptor is required for binding of Grb2 and SHP-2 but not for activation of Ras or cell proliferation.

PubMed Central

Bazenet, C E; Gelderloos, J A; Kazlauskas, A

1996-01-01

Following binding of platelet-derived growth factor (PDGF), the PDGF alpha receptor (alphaPDGFR) becomes tyrosine phosphorylated and associates with a number of signal transduction molecules, including phospholipase Cgamma-1 (PLCgamma-1), phosphatidylinositol 3-kinase (PI3K), the phosphotyrosine phosphatase SHP-2, Grb2, and Src. Here, we present data identifying a novel phosphorylation site in the kinase insert domain of the alphaPDGFR at tyrosine (Y) 720. We replaced this residue with phenylalanine and expressed the mutated receptor (F720) in Patch fibroblasts that do not express the alphaPDGFR. Characterization of the F720 mutant indicated that binding of two proteins, SHP-2 and Grb2, was severely impaired, whereas PLCgamma-1 and PI3K associated to wild-type levels. In addition, mutating Y720 to phenylalanine dramatically reduced PDGF-dependent tyrosine phosphorylation of SHP-2. Since Y720 was required for recruitment of two proteins, we investigated the mechanism by which these two proteins associated with the alphaPDGFR. SHP-2 bound the alphaPDGFR directly, whereas Grb2 associated indirectly, most probably via SHP-2, as Grb2 and SHP-2 coimmunoprecipitated when SHP-2 was tyrosine phosphorylated. We also compared the ability of the wild-type and F720 alphaPDGFRs to mediate a number of downstream events. Preventing the alphaPDGFR from recruiting SHP-2 and Grb2 did not compromise PDGF-AA-induced activation of Ras, initiation of DNA synthesis, or growth of cells in soft agar. We conclude that phosphorylation of the alphaPDGFR at Y720 is required for association of SHP-2 and Grb2 and tyrosine phosphorylation of SHP-2; however, these events are not required for the alphaPDGFR to activate Ras or initiate a proliferative response. In addition, these findings reveal that while SHP-2 binds to both of the receptors, it binds in different locations: to the carboxy terminus of the betaPDGFR but to the kinase insert of the alphaPDGFR. PMID:8943348

Prompt Emission of GRB 121217A from Gamma-Rays to the Near-Infrared

NASA Technical Reports Server (NTRS)

Elliott, J.; Yu, H.-F.; Schmidl, S.; Greiner, J.; Gruber, D.; Oates, S.; Kobayashi, S.; Zhang, B.; Cummings, J. R.; Filgas, R.;

Potent blockade of hepatocyte growth factor-stimulated cell motility, matrix invasion and branching morphogenesis by antagonists of Grb2 Src homology 2 domain interactions.

PubMed

Atabey, N; Gao, Y; Yao, Z J; Breckenridge, D; Soon, L; Soriano, J V; Burke, T R; Bottaro, D P

2001-04-27

Hepatocyte growth factor (HGF) stimulates mitogenesis, motogenesis, and morphogenesis in a wide range of cellular targets during development, homeostasis and tissue regeneration. Inappropriate HGF signaling occurs in several human cancers, and the ability of HGF to initiate a program of protease production, cell dissociation, and motility has been shown to promote cellular invasion and is strongly linked to tumor metastasis. Upon HGF binding, several tyrosines within the intracellular domain of its receptor, c-Met, become phosphorylated and mediate the binding of effector proteins, such as Grb2. Grb2 binding through its SH2 domain is thought to link c-Met with downstream mediators of cell proliferation, shape change, and motility. We analyzed the effects of Grb2 SH2 domain antagonists on HGF signaling and observed potent blockade of cell motility, matrix invasion, and branching morphogenesis, with ED(50) values of 30 nm or less, but only modest inhibition of mitogenesis. These compounds are 1000-10,000-fold more potent anti-motility agents than any previously characterized Grb2 SH2 domain antagonists. Our results suggest that SH2 domain-mediated c-Met-Grb2 interaction contributes primarily to the motogenic and morphogenic responses to HGF, and that these compounds may have therapeutic application as anti-metastatic agents for tumors where the HGF signaling pathway is active.

Constraints on violation of Lorentz invariance from atmospheric showers initiated by multi-TeV photons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubtsov, Grigory; Satunin, Petr; Sibiryakov, Sergey, E-mail: grisha@ms2.inr.ac.ru, E-mail: satunin@ms2.inr.ac.ru, E-mail: Sergey.Sibiryakov@cern.ch

2017-05-01

Parameterizing hypothetical violation of Lorentz invariance at high energies using the framework of effective quantum field theory, we discuss its effect on the formation of atmospheric showers by very-high-energy gamma rays. In the scenario where Lorentz invariance violation leads to a decrease of the photon velocity with energy the formation of the showers is suppressed compared to the Lorentz invariant case. Absence of such suppression in the high-energy part of spectrum of the Crab nebula measured independently by HEGRA and H.E.S.S. collaborations is used to set lower bounds on the energy scale of Lorentz invariance violation. These bounds are competitivemore » with the strongest existing constraints obtained from timing of variable astrophysical sources and the absorption of TeV photons on the extragalactic background light. They will be further improved by the next generation of multi-TeV gamma-ray observatories.« less

COMPTEL Studies of Gamma-Ray Bursts at MeV Energies

NASA Technical Reports Server (NTRS)

McConnell, Mark L.

1999-01-01

The purpose of this program was to analyse and interpret gamma-ray burst (GRB) data using both telescope mode data and single detector burst mode data from COMPTEL. Collectively, these data span the energy range from 300 keV up to 30 MeV. The initial goal of our proposal was to perform a standard analysis for each significant GRB event seen by COMPTEL. This includes GRBs that are registered by the telescope mode data as well as GRBs that are registered only in the burst mode data. (The latter category includes both GRBs that he outside of the FoV as well as GRBs within the FoV that are too weak to be seen in the telescope mode.) A second goal of our proposal was to define a set of data products (including deconvolved photon spectra) that, for each detected GRB event, would be made available via the COMPTEL GRB Web Page. The third goal of our program was to perform more detailed studies of selected GRB events. This represented a continuation of past GRB studies by the COMPTEL team. In general, we have met with only limited success in achieving these goals, in part due to the limited resources provided and our philosophy of utilizing local high school students to participate in this effort. Using local high school student support, however, we expect that considerable progress will be made in our efforts to catalog the COMPTEL gamma-ray burst data between now and the end of the current academic year. In addition, observations with COMPTEL contributed to an analysis of GRB 990123, the first gamma-ray burst with simultaneous optical observations.

Investigating a population of infrared-bright gamma-ray burst host galaxies

NASA Astrophysics Data System (ADS)

Chrimes, Ashley A.; Stanway, Elizabeth R.; Levan, Andrew J.; Davies, Luke J. M.; Angus, Charlotte R.; Greis, Stephanie M. L.

2018-07-01

We identify and explore the properties of an infrared-bright gamma-ray burst (GRB) host population. Candidate hosts are selected by coincidence with sources in WISE, with matching to random coordinates and a false alarm probability analysis showing that the contamination fraction is ˜0.5. This methodology has already identified the host galaxy of GRB 080517. We combine survey photometry from Pan-STARRS, SDSS, APASS, 2MASS, GALEX, and WISE with our own WHT/ACAM and VLT/X-shooter observations to classify the candidates and identify interlopers. Galaxy SED fitting is performed using MAGPHYS, in addition to stellar template fitting, yielding 13 possible IR-bright hosts. A further seven candidates are identified from the previously published work. We report a candidate host for GRB 061002, previously unidentified as such. The remainder of the galaxies have already been noted as potential hosts. Comparing the IR-bright population properties including redshift z, stellar mass M⋆, star formation rate SFR, and V-band attenuation AV to GRB host catalogues in the literature, we find that the infrared-bright population is biased towards low z, high M⋆, and high AV. This naturally arises from their initial selection - local and dusty galaxies are more likely to have the required IR flux to be detected in WISE. We conclude that while IR-bright GRB hosts are not a physically distinct class, they are useful for constraining existing GRB host populations, particularly for long GRBs.

Investigating a population of infrared-bright gamma-ray burst host galaxies

NASA Astrophysics Data System (ADS)

Chrimes, Ashley A.; Stanway, Elizabeth R.; Levan, Andrew J.; Davies, Luke J. M.; Angus, Charlotte R.; Greis, Stephanie M. L.

2018-04-01

We identify and explore the properties of an infrared-bright gamma-ray burst (GRB) host population. Candidate hosts are selected by coincidence with sources in WISE, with matching to random coordinates and a false alarm probability analysis showing that the contamination fraction is ˜ 0.5. This methodology has already identified the host galaxy of GRB 080517. We combine survey photometry from Pan-STARRS, SDSS, APASS, 2MASS, GALEX and WISE with our own WHT/ACAM and VLT/X-shooter observations to classify the candidates and identify interlopers. Galaxy SED fitting is performed using MAGPHYS, in addition to stellar template fitting, yielding 13 possible IR-bright hosts. A further 7 candidates are identified from previously published work. We report a candidate host for GRB 061002, previously unidentified as such. The remainder of the galaxies have already been noted as potential hosts. Comparing the IR-bright population properties including redshift z, stellar mass M⋆, star formation rate SFR and V-band attenuation AV to GRB host catalogues in the literature, we find that the infrared-bright population is biased toward low z, high M⋆ and high AV. This naturally arises from their initial selection - local and dusty galaxies are more likely to have the required IR flux to be detected in WISE. We conclude that while IR-bright GRB hosts are not a physically distinct class, they are useful for constraining existing GRB host populations, particularly for long GRBs.

Constraints on Lorentz Invariance Violation from Fermi -Large Area Telescope Observations of Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Vasileiou, V.; Jacholkowska, A.; Piron, F.; Bolmont, J.; Courturier, C.; Granot, J.; Stecker, Floyd William; Cohen-Tanugi, J.; Longo, F.

2013-01-01

We analyze the MeV/GeV emission from four bright Gamma-Ray Bursts (GRBs) observed by the Fermi-Large Area Telescope to produce robust, stringent constraints on a dependence of the speed of light in vacuo on the photon energy (vacuum dispersion), a form of Lorentz invariance violation (LIV) allowed by some Quantum Gravity (QG) theories. First, we use three different and complementary techniques to constrain the total degree of dispersion observed in the data. Additionally, using a maximally conservative set of assumptions on possible source-intrinsic spectral-evolution effects, we constrain any vacuum dispersion solely attributed to LIV. We then derive limits on the "QG energy scale" (the energy scale that LIV-inducing QG effects become important, E(sub QG)) and the coefficients of the Standard Model Extension. For the subluminal case (where high energy photons propagate more slowly than lower energy photons) and without taking into account any source-intrinsic dispersion, our most stringent limits (at 95% CL) are obtained from GRB 090510 and are E(sub QG,1) > 7.6 times the Planck energy (E(sub Pl)) and E(sub QG,2) > 1.3×10(exp 11) GeV for linear and quadratic leading order LIV-induced vacuum dispersion, respectively. These limits improve the latest constraints by Fermi and H.E.S.S. by a factor of approx. 2. Our results disfavor any class of models requiring E(sub QG,1) < or approx. E(sub Pl)

Constraints on Lorentz invariance violation from Fermi -Large Area Telescope observations of gamma-ray bursts

DOE PAGES

Vasileiou, V.; Jacholkowska, A.; Piron, F.; ...

2013-06-04

For this research, we analyze the MeV/GeV emission from four bright gamma-ray bursts (GRBs) observed by the Fermi Large Area Telescope to produce robust, stringent constraints on a dependence of the speed of light in vacuo on the photon energy (vacuum dispersion), a form of Lorentz invariance violation (LIV) allowed by some quantum gravity (QG) theories. First, we use three different and complementary techniques to constrain the total degree of dispersion observed in the data. Additionally, using a maximally conservative set of assumptions on possible source-intrinsic, spectral-evolution effects, we constrain any vacuum dispersion solely attributed to LIV. We then derivemore » limits on the QG energy scale (the energy scale where LIV-inducing QG effects become strong, E QG) and the coefficients of the Standard Model Extension. For the subluminal case (where high-energy photons propagate more slowly than lower-energy photons) and without taking into account any source-intrinsic dispersion, our most stringent limits (at 95% C.L.) are obtained from GRB 090510 and are E QG,1 > 7.6 times the Planck energy (E Pl) and E QG,2 > 1.3 × 10 11 GeV for linear and quadratic leading-order LIV-induced vacuum dispersion, respectively. In conclusion, these limits improve the latest constraints by Fermi and H.E.S.S. by a factor of ~2 . Our results disfavor any class of models requiring E QG,1 ≲ E Pl .« less

Extremely Bright GRB 160625B with Multiple Emission Episodes: Evidence for Long-term Ejecta Evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, Hou-Jun; Lü, Jing; Zhong, Shu-Qing

GRB 160625B is an extremely bright GRB with three distinct emission episodes. By analyzing its data observed with the Gamma-Ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board the Fermi mission, we find that a multicolor blackbody (mBB) model can be used to fit very well the spectra of the initial short episode (Episode I) within the hypothesis of photosphere emission of a fireball model. The time-resolved spectra of its main episode (Episode II), which was detected with both GBM and LAT after a long quiescent stage (∼180 s) following the initial episode, can be fitted with amore » model comprising an mBB component plus a cutoff power-law (CPL) component. This GRB was detected again in the GBM and LAT bands with a long extended emission (Episode III) after a quiescent period of ∼300 s. The spectrum of Episode III is adequately fitted with CPL plus single power-law models, and no mBB component is required. These features may imply that the emission of the three episodes are dominated by distinct physics processes, i.e., Episode I is possible from the cocoon emission surrounding the relativistic jet, Episode II may be from photosphere emission and internal shock of the relativistic jet, and Episode III is contributed by internal and external shocks of the relativistic jet. On the other hand, both X-ray and optical afterglows are consistent with the standard external shocks model.« less

Extremely Bright GRB 160625B with Multiple Emission Episodes: Evidence for Long-term Ejecta Evolution

NASA Astrophysics Data System (ADS)

Lü, Hou-Jun; Lü, Jing; Zhong, Shu-Qing; Huang, Xiao-Li; Zhang, Hai-Ming; Lan, Lin; Xie, Wei; Lu, Rui-Jing; Liang, En-Wei

2017-11-01

GRB 160625B is an extremely bright GRB with three distinct emission episodes. By analyzing its data observed with the Gamma-Ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board the Fermi mission, we find that a multicolor blackbody (mBB) model can be used to fit very well the spectra of the initial short episode (Episode I) within the hypothesis of photosphere emission of a fireball model. The time-resolved spectra of its main episode (Episode II), which was detected with both GBM and LAT after a long quiescent stage (˜180 s) following the initial episode, can be fitted with a model comprising an mBB component plus a cutoff power-law (CPL) component. This GRB was detected again in the GBM and LAT bands with a long extended emission (Episode III) after a quiescent period of ˜300 s. The spectrum of Episode III is adequately fitted with CPL plus single power-law models, and no mBB component is required. These features may imply that the emission of the three episodes are dominated by distinct physics processes, I.e., Episode I is possible from the cocoon emission surrounding the relativistic jet, Episode II may be from photosphere emission and internal shock of the relativistic jet, and Episode III is contributed by internal and external shocks of the relativistic jet. On the other hand, both X-ray and optical afterglows are consistent with the standard external shocks model.

How Special Is GRB 170817A?

NASA Astrophysics Data System (ADS)

Yue, Chuan; Hu, Qian; Zhang, Fu-Wen; Liang, Yun-Feng; Jin, Zhi-Ping; Zou, Yuan-Chuan; Fan, Yi-Zhong; Wei, Da-Ming

2018-01-01

GRB 170817A is the first short gamma-ray burst (GRB) with direct detection of the gravitational-wave radiation and also the spectroscopically identified macronova emission (i.e., AT 2017gfo). The prompt emission of this burst, however, is underluminous in comparison with the other short GRBs with known redshift. In this work, we examine whether GRB 170817A is indeed unique. We first show that GRB 130603B/macronova may be the on-axis “analogs” of GRB 170817A/AT 2017gfo, and the extremely dim but long-lasting afterglow emission of GRB 170817A may suggest a low number density (∼ {10}-5 {{cm}}-3) of its circumburst medium and a structured outflow. We then discuss whether GRB 070923, GRB 080121, GRB 090417A, GRB 111005A, and GRB 170817A form a new group of very nearby underluminous GRBs originated from neutron star mergers. If the short events GRB 070923, GRB 080121, and GRB 090417A are indeed at a redshift of ∼ 0.076, 0.046, 0.088, respectively, their isotropic energies of the prompt emission are ∼ {10}47 erg and thus comparable to the other two events. The non-detection of optical counterparts of GRB 070923, GRB 080121, GRB 090417A, and GRB 111005A, however, strongly suggests that the macronovae from neutron star mergers are significantly diverse in luminosities or, alternatively, there is another origin channel (for instance, the white dwarf and black hole mergers). We finally suggest that GW170817/GRB 170817A are likely not alone and similar events will be detected by the upgraded/upcoming gravitational-wave detectors and the electromagnetic monitors.

Transparency Parameters from Relativistically Expanding Outflows

NASA Astrophysics Data System (ADS)

Bégué, D.; Iyyani, S.

2014-09-01

In many gamma-ray bursts a distinct blackbody spectral component is present, which is attributed to the emission from the photosphere of a relativistically expanding plasma. The properties of this component (temperature and flux) can be linked to the properties of the outflow and have been presented in the case where there is no sub-photospheric dissipation and the photosphere is in coasting phase. First, we present the derivation of the properties of the outflow for finite winds, including when the photosphere is in the accelerating phase. Second, we study the effect of localized sub-photospheric dissipation on the estimation of the parameters. Finally, we apply our results to GRB 090902B. We find that during the first epoch of this burst the photosphere is most likely to be in the accelerating phase, leading to smaller values of the Lorentz factor than the ones previously estimated. For the second epoch, we find that the photosphere is likely to be in the coasting phase.

Lorentz Invariance Violation: the Latest Fermi Results and the GRB-AGN Complementarity

NASA Technical Reports Server (NTRS)

Bolmont, J.; Vasileiou, V.; Jacholkowska, A.; Piron, F.; Couturier, C.; Granot, J.; Stecker, F. W.; Cohen-Tanugi, J.; Longo, F.

2013-01-01

Because they are bright and distant, Gamma-ray Bursts (GRBs) have been used for more than a decade to test propagation of photons and to constrain relevant Quantum Gravity (QG) models in which the velocity of photons in vacuum can depend on their energy. With its unprecedented sensitivity and energy coverage, the Fermi satellite has provided the most constraining results on the QG energy scale so far. In this talk, the latest results obtained from the analysis of four bright GRBs observed by the Large Area Telescope will be reviewed. These robust results, cross-checked using three different analysis techniques set the limit on QG energy scale at E(sub QG,1) greater than 7.6 times the Planck energy for linear dispersion and E(sub QG,2) greater than 1.3 x 10(exp 11) gigaelectron volts for quadratic dispersion (95% CL). After describing the data and the analysis techniques in use, results will be discussed and confronted to latest constraints obtained with Active Galactic Nuclei.

Supernovae and gamma-ray bursts: The moment of the formation of a black hole and a newly born neutron star

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ruffini, Remo, E-mail: ruffini@icra.it; ICRANet, Piazzale della Repubblica 10, I-65122 Pescara; Université de Nice Sophie Antipolis, Nice, CEDEX 2 Grand Château Parc Valros

2014-01-14

We review recent progress in our understanding of the nature of gamma ray bursts (GRBs) and in particular, in the relationship between the short GRBs and the long GRBs. The coincidental occurence of a GRB with a Supernova (SN) is explained within the Induced Gravitational Collapse (IGC) paradigm, following the sequence: 1) an initial binary system consists in a compact Carbon-Oxygen (CO) core and a NS; 2) the CO core explodes giving origin to a SN and part of the SN ejecta accretes onto the NS which reaches its critical mass and collapses to a BH giving rise to amore » long GRB; 3) a new NS is generated by the SN as a remnant. The observational consequences of this scenario are outlined. The first example of a short GRB is given.« less

On the Time Evolution of Gamma-Ray Burst Pulses: A Self-Consistent Description.

PubMed

Ryde; Svensson

2000-01-20

For the first time, the consequences of combining two well-established empirical relations that describe different aspects of the spectral evolution of observed gamma-ray burst (GRB) pulses are explored. These empirical relations are (1) the hardness-intensity correlation and (2) the hardness-photon fluence correlation. From these we find a self-consistent, quantitative, and compact description for the temporal evolution of pulse decay phases within a GRB light curve. In particular, we show that in the case in which the two empirical relations are both valid, the instantaneous photon flux (intensity) must behave as 1&solm0;&parl0;1+t&solm0;tau&parr0;, where tau is a time constant that can be expressed in terms of the parameters of the two empirical relations. The time evolution is fully defined by two initial constants and two parameters. We study a complete sample of 83 bright GRB pulses observed by the Compton Gamma-Ray Observatory and identify a major subgroup of GRB pulses ( approximately 45%) which satisfy the spectral-temporal behavior described above. In particular, the decay phase follows a reciprocal law in time. It is unclear what physics causes such a decay phase.

A New Paradigm for Gamma Ray Bursts: Long Term Accretion Rate Modulation by an External Accretion Disk

NASA Technical Reports Server (NTRS)

Cannizzo, John; Gehrels, Neil

2009-01-01

We present a new way of looking at the very long term evolution of GRBs in which the disk of material surrounding the putative black hole powering the GRB jet modulates the mass flow, and hence the efficacy of the process that extracts rotational energy from the black hole and inner accretion disk. The pre-Swift paradigm of achromatic, shallow-to-steep "breaks" in the long term GRB light curves has not been borne out by detailed Swift data amassed in the past several years. We argue that, given the initial existence of a fall-back disk near the progenitor, an unavoidable consequence will be the formation of an "external disk" whose outer edge continually moves to larger radii due to angular momentum transport and lack of a confining torque. The mass reservoir at large radii moves outward with time and gives a natural power law decay to the GRB light curves. In this model, the different canonical power law decay segments in the GRB identified by Zhang et al. and Nousek et al. represent different physical states of the accretion disk. We identify a physical disk state with each power law segment.

MODELING THE AFTERGLOW OF THE POSSIBLE FERMI -GBM EVENT ASSOCIATED WITH GW150914

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morsony, Brian J.; Workman, Jared C.; Ryan, Dominic M., E-mail: morsony@astro.umd.edu

2016-07-10

We model the possible afterglow of the Fermi Gamma-ray Burst Monitor (GBM) event associated with LIGO detection GW150914, under the assumption that the gamma-rays are produced by a short GRB-like relativistic outflow. We model GW150914-GBM as both a weak, on-axis short GRB and normal short GRB seen far off-axis. Given the large uncertainty in the position of GW150914, we determine that the best chance of finding the afterglow is with ASKAP or possibly the Murchinson Widefield Array (MWA), with the flux from an off-axis short GRB reaching 0.2–4 mJy (0.12–16 mJy) at 150 MHz (863.5 MHz) by 1–12 months aftermore » the initial event. At low frequencies, the source would evolve from a hard to soft spectrum over several months. The radio afterglow would be detectable for several months to years after it peaks, meaning the afterglow may still be detectable and increasing in brightness NOW (2016 mid-July). With a localization from the MWA or ASKAP, the afterglow would be detectable at higher radio frequencies with the ATCA and in X-rays with Chandra or XMM .« less

GRB 111005A at z = 0.0133 and the Prospect of Establishing Long-Short GRB/GW Association

NASA Astrophysics Data System (ADS)

Wang, Yuan-Zhu; Huang, Yong-Jia; Liang, Yun-Feng; Li, Xiang; Jin, Zhi-Ping; Zhang, Fu-Wen; Zou, Yuan-Chuan; Fan, Yi-Zhong; Wei, Da-Ming

2017-12-01

GRB 111005A, a long-duration gamma-ray burst (GRB) that occurred within a metal-rich environment that lacks massive stars with {M}{ZAMS}≥slant 15 {M}⊙ , is not coincident with supernova emission down to a stringent limit and thus should be classified as a “long-short” GRB (lsGRB; also known as an SN-less long GRB or hybrid GRB), like GRB 060505 and GRB 060614. In this work, we show that in the neutron star merger model the non-detection of the optical/infrared emission of GRB 111005A requires sub-relativistic neutron-rich ejecta with a mass of ≤slant 0.01 {M}⊙ , which is (significantly) less massive than that of GRB 130603B, GRB 060614, GRB 050709, and GRB 170817A. The lsGRBs are found to have a high rate density and the neutron star merger origin model can be unambiguously tested by the joint observations of the second-generation gravitational-wave (GW) detectors and the full-sky gamma-ray monitors such as Fermi-GBM and the proposed GECAM. If no lsGRB/GW association is observed in the 2020s, alternative scenarios have to be systematically investigated. With the detailed environmental information achievable for the nearby events, a novel kind of merger or explosion origin may be identified.

The origins of length contraction: I. The FitzGerald-Lorentz deformation hypothesis

NASA Astrophysics Data System (ADS)

Brown, Harvey R.

2001-10-01

"Can there be some point in the theory of Mr. Michelson's experiment which has yet been overlooked?" H. A. Lorentz, letter to Lord Rayleigh, August 1892. One of the widespread confusions concerning the history of the 1887 Michelson-Morley experiment has to do with the initial explanation of this celebrated null result due independently to FitzGerald and Lorentz. In neither case was a strict, longitudinal length contraction hypothesis invoked, as is commonly supposed. Lorentz postulated, particularly in 1895, any one of a certain family of possible deformation effects for rigid bodies in motion, including purely transverse alteration, and expansion as well as contraction; FitzGerald may well have had the same family in mind. A careful analysis of the Michelson-Morley experiment (which reveals a number of serious inadequacies in many textbook treatments) indeed shows that strict contraction is not required.

Bulk Lorentz factors of gamma-ray bursts

NASA Astrophysics Data System (ADS)

Ghirlanda, G.; Nappo, F.; Ghisellini, G.; Melandri, A.; Marcarini, G.; Nava, L.; Salafia, O. S.; Campana, S.; Salvaterra, R.

2018-01-01

Knowledge of the bulk Lorentz factor Γ0 of gamma-ray bursts (GRBs) allows us to compute their comoving frame properties shedding light on their physics. Upon collisions with the circumburst matter, the fireball of a GRB starts to decelerate, producing a peak or a break (depending on the circumburst density profile) in the light curve of the afterglow. Considering all bursts with known redshift and with an early coverage of their emission, we find 67 GRBs (including one short event) with a peak in their optical or GeV light curves at a time tp. For another 106 GRBs we set an upper limit tpUL. The measure of tp provides the bulk Lorentz factor Γ0 of the fireball before deceleration. We show that tp is due to the dynamics of the fireball deceleration and not to the passage of a characteristic frequency of the synchrotron spectrum across the optical band. Considering the tp of 66 long GRBs and the 85 most constraining upper limits, we estimate Γ0 or a lower limit Γ0LL. Using censored data analysis methods, we reconstruct the most likely distribution of tp. All tp are larger than the time Tp,γ when the prompt γ-ray emission peaks, and are much larger than the time Tph when the fireball becomes transparent, that is, tp>Tp,γ>Tph. The reconstructed distribution of Γ0 has median value 300 (150) for a uniform (wind) circumburst density profile. In the comoving frame, long GRBs have typical isotropic energy, luminosity, and peak energy ⟨ Eiso ⟩ = 3(8) × 1050 erg, ⟨ Liso ⟩ = 3(15) × 1047 erg s-1, and ⟨ Epeak ⟩ = 1(2) keV in the homogeneous (wind) case. We confirm that the significant correlations between Γ0 and the rest frame isotropic energy (Eiso), luminosity (Liso), and peak energy (Ep) are not due to selection effects. When combined, they lead to the observed Ep-Eiso and Ep-Liso correlations. Finally, assuming a typical opening angle of 5 degrees, we derive the distribution of the jet baryon loading which is centered around a few 10-6M⊙.

Insight into the Selectivity of the G7-18NATE Inhibitor Peptide for the Grb7-SH2 Domain Target.

PubMed

Watson, Gabrielle M; Lucas, William A H; Gunzburg, Menachem J; Wilce, Jacqueline A

2017-01-01

Growth factor receptor bound protein 7 (Grb7) is an adaptor protein with established roles in the progression of both breast and pancreatic cancers. Through its C-terminal SH2 domain, Grb7 binds to phosphorylated tyrosine kinases to promote proliferative and migratory signaling. Here, we investigated the molecular basis for the specificity of a Grb7 SH2-domain targeted peptide inhibitor. We identified that arginine 462 in the BC loop is unique to Grb7 compared to Grb2, another SH2 domain bearing protein that shares the same consensus binding motif as Grb7. Using surface plasmon resonance we demonstrated that Grb7-SH2 binding to G7-18NATE is reduced 3.3-fold when the arginine is mutated to the corresponding Grb2 amino acid. The reverse mutation in Grb2-SH2 (serine to arginine), however, was insufficient to restore binding of G7-18NATE to Grb2-SH2. Further, using a microarray, we confirmed that G7-18NATE is specific for Grb7 over a panel of 79 SH2 domains, and identified that leucine at the βD6 position may also be a requirement for Grb7-SH2 binding. This study provides insight into the specificity defining features of Grb7 for the inhibitor molecule G7-18NATE, that will assist in the development of improved Grb7 targeted inhibitors.

Insight into the Selectivity of the G7-18NATE Inhibitor Peptide for the Grb7-SH2 Domain Target

PubMed Central

Watson, Gabrielle M.; Lucas, William A. H.; Gunzburg, Menachem J.; Wilce, Jacqueline A.

2017-01-01

Growth factor receptor bound protein 7 (Grb7) is an adaptor protein with established roles in the progression of both breast and pancreatic cancers. Through its C-terminal SH2 domain, Grb7 binds to phosphorylated tyrosine kinases to promote proliferative and migratory signaling. Here, we investigated the molecular basis for the specificity of a Grb7 SH2-domain targeted peptide inhibitor. We identified that arginine 462 in the BC loop is unique to Grb7 compared to Grb2, another SH2 domain bearing protein that shares the same consensus binding motif as Grb7. Using surface plasmon resonance we demonstrated that Grb7-SH2 binding to G7-18NATE is reduced 3.3-fold when the arginine is mutated to the corresponding Grb2 amino acid. The reverse mutation in Grb2-SH2 (serine to arginine), however, was insufficient to restore binding of G7-18NATE to Grb2-SH2. Further, using a microarray, we confirmed that G7-18NATE is specific for Grb7 over a panel of 79 SH2 domains, and identified that leucine at the βD6 position may also be a requirement for Grb7-SH2 binding. This study provides insight into the specificity defining features of Grb7 for the inhibitor molecule G7-18NATE, that will assist in the development of improved Grb7 targeted inhibitors. PMID:29018805

Multi-wavelength observations of the GRB 080319B afterglow and the modeling constraints

NASA Astrophysics Data System (ADS)

Pandey, S. B.; Castro-Tirado, A. J.; Jelínek, M.; Kamble, A. P.; Gorosabel, J.; de Ugarte Postigo, A.; Prins, S.; Oreiro, R.; Chantry, V.; Trushkin, S.; Bremer, M.; Winters, J. M.; Pozanenko, A.; Krugly, Yu.; Slyusarev, I.; Kornienko, G.; Erofeeva, A.; Misra, K.; Ramprakash, A. N.; Mohan, V.; Bhattacharya, D.; Volnova, A.; Plá, J.; Ibrahimov, M.; Im, M.; Volvach, A.; Wijers, R. A. M. J.

2009-09-01

Context: We present observations of the GRB 080319B afterglow at optical, mm, and radio frequencies between a few hours and 67 days after the burst. Aims: We attempt to understand the nature of this extraordinarily bright explosion based on the observed properties and its comparison with afterglow models. Methods: Our observations and other published multiwavelength data were used to reconstruct the light curves and spectral energy distributions of the burst afterglow. Results: Our results indicate that the observed features of the afterglow agrees equally well with the inter stellar matter and the stellar wind density profiles of the circumburst medium. In the case of both density profiles, the maximum synchrotron frequency νm is below optical value and the cooling break frequency νc is below X-rays, ~104 s after the burst. The derived value of the Lorentz factor at the time of naked-eye brightness is also ~300 for a corresponding blast-wave size of ~1018 cm. Conclusions: The numerical fit to the multiwavelength afterglow data constraints the values of physical parameters and the emission mechanism of the burst. Based on observations obtained with the 0.22 m telescope at Russia the 0.7 m telescope at of Kharkov University, Ukraine, the 0.8 m telescope at Observatorio del Teide (IAC-80), Spain the 1.2 m Mercator telescope at La Palma, Spain, the 1.5 m telescope of Maidanak observatory Uzbekistan, the 2.0 m IGO Telescope at IUCAA Pune, India, the 2.5 m NOT, the PdB millimeter interferometric array France, the RATAN-600 Radio Telescope at Russia and the RT-22 radio telescope of CrAO, Ukraine.

Long-Lag, Wide-pulse Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Norris, J. P.; Bonnell, J. T.; Kazanas, D.; Scargie, J. D.; Hakkila, J.; Giblin, T. W.

2005-01-01

The best available probe of the early phase of gamma-ray burst (GRB) jet attributes is the prompt gamma-ray emission, in which several intrinsic and extrinsic variables determine observed GRB pulse evolution, including at least: jet opening angle, profiles of Lorentz factor and matter/field density, distance of emission region from central source, and viewing angle. Bright, usually complex bursts have many narrow pulses that are difficult to model due to overlap. However, the relatively simple, long spectral lag, wide-pulse bursts may have simpler physics and are easier to model. We have analyzed the temporal and spectral behavior of wide pulses in 24 long-lag bursts from the BATSE sample, using a pulse model with two shape parameters - width and asymmetry - and the Band spectral model with three shape parameters. We find that pulses in long-lag bursts are distinguished both temporally and spectrally from those in bright bursts: the pulses in long spectral lag bursts are few in number, and approximately 100 times wider (10s of seconds), have systemtically lower peaks in nu*F(nu), harder low-energy spectra and softer high-energy spectra. These five pulse descriptors are essentially uncorrelated for our long-lag sample, suggesting that at least approximately 5 parameters are needed to model burst temporal and spectral behavior, roughly commensurate with the theoretical phase space. However, we do find that pulse width is strongly correlated with spectral lag; hence these two parameters may be viewed as mutual surrogates. The prevalence of long-lag bursts near the BATSE trigger threshold, their predominantly low nu*F(nu) spectral peaks, and relatively steep upper power-law spectral indices indicate that Swiift will detect many such bursts.

Cooling Timescales and Temporal Structure of Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Sari, Re'em; Narayan, Ramesh; Piran, Tsvi

1996-12-01

A leading mechanism for producing cosmological gamma-ray bursts (GRBs) is via ultrarelativistic particles in an expanding fireball. The kinetic energy of the particles is converted into thermal energy in two shocks, a forward shock and a reverse shock, when the outward flowing particles encounter the interstellar medium. The thermal energy is then radiated via synchrotron emission and Comptonization. We estimate the synchrotron cooling timescale of the shocked material in the forward and reverse shocks for electrons of various Lorentz factors, focusing in particular on those electrons whose radiation falls within the energy detection range of the BATSE detectors. We find that in order to produce the rapid variability observed in most bursts, the energy density of the magnetic field in the shocked material must be greater than about 1% of the thermal energy density. In addition, the electrons must be nearly in equipartition with the protons, since otherwise we do not have reasonable radiative efficiencies of GRBs. Inverse Compton scattering can increase the cooling rate of the relevant electrons, but the Comptonized emission itself is never within the BATSE range. These arguments allow us to pinpoint the conditions within the radiating regions in GRBs and to determine the important radiation processes. In addition, they provide a plausible explanation for several observations. The model predicts that the duty cycle of intensity variations in GRB light curves should be nearly independent of burst duration and should scale inversely as the square root of the observed photon energy. Both correlations are in agreement with observations. The model also provides a plausible explanation for the bimodal distribution of burst durations. There is no explanation, however, for the presence of a characteristic break energy in GRB spectra.

Identification and properties of the photospheric emission in GRB090902B

DOE PAGES

Ryde, F.; Axelsson, M.; Zhang, B. B.; ...

2010-01-14

We observed the Fermi Gamma-ray Space Telescope using the bright and long GRB090902B, lying at a redshift of z = 1.822. Together the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM) cover the spectral range from 8 keV to >300 GeV. Here we show that the prompt burst spectrum is consistent with emission from the jet photosphere combined with nonthermal emission described by a single power law with photon index –1.9. The photosphere gives rise to a strong quasi-blackbody spectrum which is somewhat broader than a single Planck function and has a characteristic temperature of ~290 keV. Wemore » model the photospheric emission with a multicolor blackbody, and its shape indicates that the photospheric radius increases at higher latitudes. We derive the averaged photospheric radius R ph = (1.1 ± 0.3) × 10 12 Y 1/4 cm and the bulk Lorentz factor of the flow, which is found to vary by a factor of 2 and has a maximal value of Γ = 750 Y 1/4. Here, Y is the ratio between the total fireball energy and the energy emitted in the gamma rays. Here, we find that during the first quarter of the prompt phase the photospheric emission dominates, which explains the delayed onset of the observed flux in the LAT compared to the GBM. We also interpret the broadband emission as synchrotron emission at R ~ 4 × 10 15 cm. Our analysis emphasizes the importance of having high temporal resolution when performing spectral analysis on gamma-ray bursts, since there is strong spectral evolution.« less

Polarimetry and Photometry of Gamma-Ray Bursts with RINGO2

NASA Astrophysics Data System (ADS)

Steele, I. A.; Kopač, D.; Arnold, D. M.; Smith, R. J.; Kobayashi, S.; Jermak, H. E.; Mundell, C. G.; Gomboc, A.; Guidorzi, C.; Melandri, A.; Japelj, J.

2017-07-01

We present a catalog of early-time (˜ {10}2-{10}4 s) photometry and polarimetry of all gamma-ray burst (GRB) optical afterglows observed with the RINGO2 imaging polarimeter on the Liverpool Telescope. Of the 19 optical afterglows observed, the following nine were bright enough to perform photometry and attempt polarimetry: GRB 100805A, GRB 101112A, GRB 110205A, GRB 110726A, GRB 120119A, GRB 120308A, GRB 120311A, GRB 120326A, and GRB 120327A. We present multiwavelength light curves for these 9 GRBs, together with estimates of their optical polarization degrees and/or limits. We carry out a thorough investigation of detection probabilities, instrumental properties, and systematics. Using two independent methods, we confirm previous reports of significant polarization in GRB 110205A and 120308A, and report the new detection of P={6}-2+3% in GRB101112A. We discuss the results for the sample in the context of the reverse- and forward-shock afterglow scenario, and show that GRBs with detectable optical polarization at early time have clearly identifiable signatures of reverse-shock emission in their optical light curves. This supports the idea that GRB ejecta contain large-scale magnetic fields, and it highlights the importance of rapid-response polarimetry.

GRB 060614 in the canonical fireshell model

NASA Astrophysics Data System (ADS)

Caito, L.; Bernardini, M. G.; Bianco, C. L.; Dainotti, M. G.; Guida, R.; Ruffini, R.

2008-10-01

Gamma-Ray Burst (GRB) 060614 is the first nearby long duration GRB clearly not associated to any bright Ib/c Supernova. The explosion of this burst undermines one of the fundamental assumptions of the standard scenario and opens new horizons and hints of investigation. GRB 060614, hardly classifiable as a short GRB, is not either a ``typical'' long GRB since it occurs in a low star forming region. Moreover, it presents deep similarities with GRB 970228, which is the prototype of the ``fake'' short bursts, or better canonical GRBs disguised as short ones. Within the ``fireshell'' model ([1]), we test if this ``anomalous'' source can be a disguised short GRB([2]).

Deletion of the Imprinted Gene Grb10 Promotes Hematopoietic Stem Cell Self-Renewal and Regeneration.

PubMed

Yan, Xiao; Himburg, Heather A; Pohl, Katherine; Quarmyne, Mamle; Tran, Evelyn; Zhang, Yurun; Fang, Tiancheng; Kan, Jenny; Chao, Nelson J; Zhao, Liman; Doan, Phuong L; Chute, John P

2016-11-01

Imprinted genes are differentially expressed by adult stem cells, but their functions in regulating adult stem cell fate are incompletely understood. Here we show that growth factor receptor-bound protein 10 (Grb10), an imprinted gene, regulates hematopoietic stem cell (HSC) self-renewal and regeneration. Deletion of the maternal allele of Grb10 in mice (Grb10 m/+ mice) substantially increased HSC long-term repopulating capacity, as compared to that of Grb10 +/+ mice. After total body irradiation (TBI), Grb10 m/+ mice demonstrated accelerated HSC regeneration and hematopoietic reconstitution, as compared to Grb10 +/+ mice. Grb10-deficient HSCs displayed increased proliferation after competitive transplantation or TBI, commensurate with upregulation of CDK4 and Cyclin E. Furthermore, the enhanced HSC regeneration observed in Grb10-deficient mice was dependent on activation of the Akt/mTORC1 pathway. This study reveals a function for the imprinted gene Grb10 in regulating HSC self-renewal and regeneration and suggests that the inhibition of Grb10 can promote hematopoietic regeneration in vivo. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Constraints on millisecond magnetars as the engines of prompt emission in gamma-ray bursts

NASA Astrophysics Data System (ADS)

Beniamini, Paz; Giannios, Dimitrios; Metzger, Brian D.

2017-12-01

We examine millisecond magnetars as central engines of gamma-ray bursts' (GRBs) prompt emission. Using the protomagnetar wind model of Metzger et al., we estimate the temporal evolution of the magnetization and power injection at the base of the GRB jet and apply these to different prompt emission models to make predictions for the GRB energetics, spectra and light curves. We investigate both shock and magnetic reconnection models for the particle acceleration, as well as the effects of energy dissipation across optically thick and thin regions of the jet. The magnetization at the base of the jet, σ0, is the main parameter driving the GRB evolution in the magnetar model and the emission is typically released for 100 ≲σ0 ≲3000. Given the rapid increase in σ0 as the protomagnetar cools and its neutrino-driven mass loss subsides, the GRB duration is typically limited to ≲100 s. This low baryon loading at late times challenges magnetar models for ultralong GRBs, though black hole models likely run into similar difficulties without substantial entrainment from the jet walls. The maximum radiated gamma-ray energy is ≲5 × 1051 erg, significantly less than the magnetar's total initial rotational energy and in strong tension with the high end of the observed GRB energy distribution. However, the gradual magnetic dissipation model applied to a magnetar central engine, naturally explains several key observables of typical GRBs, including energetics, durations, stable peak energies, spectral slopes and a hard to soft evolution during the burst.

Active control and synchronization chaotic satellite via the geomagnetic Lorentz force

NASA Astrophysics Data System (ADS)

Abdel-Aziz, Yehia

2016-07-01

The use of geomagnetic Lorentz force is considered in this paper for the purpose of satellite attitude control. A satellite with an electrostatic charge will interact with the Earth's magnetic field and experience the Lorentz force. An analytical attitude control and synchronization two identical chaotic satellite systems with different initial condition Master/ Slave are proposed to allows a charged satellite remains near the desired attitude. Asymptotic stability for the closed-loop system are investigated by means of Lyapunov stability theorem. The control feasibility depend on the charge requirement. Given a significantly and sufficiently accurate insertion, a charged satellite could maintains the desired attitude orientation without propellant. Simulations is performed to prove the efficacy of the proposed method.

NEAR-EXTREMAL BLACK HOLES AS INITIAL CONDITIONS OF LONG GRB SUPERNOVAE AND PROBES OF THEIR GRAVITATIONAL WAVE EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Putten, Maurice H. P. M.

2015-09-01

Long gamma-ray bursts (GRBs) associated with supernovae and short GRBs with extended emission (SGRBEE) from mergers are probably powered by black holes as a common inner engine, as their prompt GRB emission satisfies the same Amati correlation in the E{sub p,i}–E{sub iso} plane. We introduce modified Bardeen equations to identify hyper-accretion driving newly formed black holes in core-collapse supernovae to near-extremal spin as a precursor to prompt GRB emission. Subsequent spin-down is observed in the BATSE catalog of long GRBs. Spin-down provides a natural unification of long durations associated with the lifetime of black hole spin for normal long GRBsmore » and SGRBEEs, given the absence of major fallback matter in mergers. The results point to major emissions unseen in high frequency gravitational waves. A novel matched filtering method is described for LIGO–Virgo and KAGRA broadband probes of nearby core-collapse supernovae at essentially maximal sensitivity.« less

One-way membrane trafficking of SOS in receptor-triggered Ras activation.

PubMed

Christensen, Sune M; Tu, Hsiung-Lin; Jun, Jesse E; Alvarez, Steven; Triplet, Meredith G; Iwig, Jeffrey S; Yadav, Kamlesh K; Bar-Sagi, Dafna; Roose, Jeroen P; Groves, Jay T

2016-09-01

SOS is a key activator of the small GTPase Ras. In cells, SOS-Ras signaling is thought to be initiated predominantly by membrane recruitment of SOS via the adaptor Grb2 and balanced by rapidly reversible Grb2-SOS binding kinetics. However, SOS has multiple protein and lipid interactions that provide linkage to the membrane. In reconstituted-membrane experiments, these Grb2-independent interactions were sufficient to retain human SOS on the membrane for many minutes, during which a single SOS molecule could processively activate thousands of Ras molecules. These observations raised questions concerning how receptors maintain control of SOS in cells and how membrane-recruited SOS is ultimately released. We addressed these questions in quantitative assays of reconstituted SOS-deficient chicken B-cell signaling systems combined with single-molecule measurements in supported membranes. These studies revealed an essentially one-way trafficking process in which membrane-recruited SOS remains trapped on the membrane and continuously activates Ras until being actively removed via endocytosis.

One-way membrane trafficking of SOS in receptor-triggered Ras activation

PubMed Central

Christensen, Sune M.; Tu, Hsiung-Lin; Jun, Jesse E.; Alvarez, Steven; Triplet, Meredith G.; Iwig, Jeffrey S.; Yadav, Kamlesh K.; Bar-Sagi, Dafna; Roose, Jeroen P.; Groves, Jay T.

2016-01-01

SOS is a key activator of the small GTPase Ras. In cells, SOS-Ras signaling is thought to be initiated predominantly by membrane-recruitment of SOS via the adaptor Grb2 and balanced by rapidly reversible Grb2:SOS binding kinetics. However, SOS has multiple protein and lipid interactions that provide linkage to the membrane. In reconstituted membrane experiments, these Grb2-independent interactions are sufficient to retain SOS on the membrane for many minutes, during which a single SOS molecule can processively activate thousands of Ras molecules. These observations raise questions concerning how receptors maintain control of SOS in cells and how membrane-recruited SOS is ultimately released. We addressed these questions in quantitative reconstituted SOS-deficient chicken B cell signaling systems combined with single molecule measurements in supported membranes. These studies reveal an essentially one-way trafficking process in which membrane-recruited SOS remains trapped on the membrane and continuously activates Ras until it is actively removed via endocytosis. PMID:27501536

The GOES-R Rebroadcast (GRB) Data Stream Simulator

NASA Astrophysics Data System (ADS)

Dittberner, G. J.; Gibbons, K.; Czopkiewicz, E.; Miller, C.; Brown-Bergtold, B.; Haman, B.; Marley, S.

2013-12-01

GOES Rebroadcast (GRB) signals in the GOES-R era will replace the current legacy GOES Variable (GVAR) signal and will have substantially different characteristics, including a change in data rate from a single 2.1 Mbps stream to two digital streams of 15.5 Mbps each. Five GRB Simulators were developed as portable systems that output a high-fidelity stream of Consultative Committee for Space Data Systems (CCSDS) formatted GRB packet data equivalent to live GRB data. The data are used for on-site testing of user ingest and data handling systems known as field terminal sites. The GRB Simulator is a fully self-contained system which includes all software and hardware units needed for operation. The operator manages configurations to edit preferences, define individual test scenarios, and manage event logs and reports. Simulations are controlled by test scenarios, which are scripts that specify the test data and provide a series of actions for the GRB Simulator to perform when generating GRB output. Scenarios allow for the insertion of errors or modification of GRB packet headers for testing purposes. The GRB Simulator provides a built-in editor for managing scenarios. The GRB Simulator provides GRB data as either baseband (digital) or Intermediate Frequency (IF) output to the test system. GRB packet data are sent in the same two output streams used in the operational system: one for Left Hand Circular Polarization (LHCP) and one for Right Hand Circular Polarization (RHCP). Use of circular polarization in the operational system allows the transmitting antenna to multiplex the two digital streams into the same signal, thereby doubling the available bandwidth. The GRB Simulator is designed to be used at sites that receive the GRB downlink.

Direct association between the Ret receptor tyrosine kinase and the Src homology 2-containing adapter protein Grb7.

PubMed

Pandey, A; Liu, X; Dixon, J E; Di Fiore, P P; Dixit, V M

1996-05-03

Adapter proteins containing Src homology 2 (SH2) domains link transmembrane receptor protein-tyrosine kinases to downstream signal transducing molecules. A family of SH2 containing adapter proteins including Grb7 and Grb10 has been recently identified. We had previously shown that Grb10 associates with Ret via its SH2 domain in an activation-dependent manner (Pandey, A., Duan, H., Di Fiore, P.P., and Dixit, V.M. (1995) J. Biol, Chem. 270, 21461-21463). We now demonstrate that the related adapter molecule Grb7 also associates with Ret in vitro and in vivo, and that the binding of the SH2 domain of Grb7 to Ret is direct. This binding is dependent upon Ret autophosphorylation since Grb7 is incapable of binding a kinase-defective mutant of Ret. Thus two members of the Grb family, Grb7 and Grb10, likely relay signals emanating from Ret to other, as yet, unidentified targets within the cell.

Long High Redshift GRB and Xrt/swift Lightcurves

NASA Astrophysics Data System (ADS)

Arkhangelskaja, Irene

At February of 2010 the volume of Swift GRB subset with known redshift consisted of more than 150 bursts. Long GRB redshift distribution analysis has shown that confidence level of single peak approximation of this distribution is only ˜60%. Moreover, more than 40% of GRB are in very heavy tails outside 3σ level for this fit. More detailed analysis of long GRB redshift distribution reveals that at 97% confidence level at least two subgroups could be separated with following parameters: = 0.9 ± 0.1 and = 2.7 ± 0.2. It allows to make conclusion that Swift long GRB sources subset is not uniform. In the presented article attention is paid on the measure of discrepancy of long GRB with z>3 and subset of other long GRB with known redshifts. XRT/Swift lightcurves for these groups of GRB were considered and it have shown that at least 90% XRT/Swift lightcurves for GRB with z>3 are more complicated and have got a number of maxima.

Grb7 protein RA domain oligomerization.

PubMed

Godamudunage, Malika P; Foster, Albert; Warren, Darius; Lyons, Barbara A

2017-08-01

The growth factor receptor bound protein 7 (Grb7) is an adaptor protein that is often coamplified with the erythroblastosis oncogene B 2 receptor in 20% to 30% of breast cancer patients. Grb7 overexpression has been linked to increased cell migration and cancer metastasis. The ras associating and pleckstrin homology domain region of Grb7 has been reported to interact with various other downstream signaling proteins such as four and half Lin11, Isl-1, Mec-3 (LIM) domains isoform 2 and filamin α. These interactions are believed to play a role in regulating Grb7-mediated cell migration function. The full-length Grb7 protein has been shown to dimerize, and the oligomeric state of the Grb7SH2 domain has been extensively studied; however, the oligomerization state of the ras associating and pleckstrin homology domains, and the importance of this oligomerization in Grb7 function, is yet to be fully known. In this study, we characterize the oligomeric state of the Grb7RA domain using size exclusion chromatography, nuclear magnetic resonance, nuclear relaxation studies, glutaraldehyde cross linking, and dynamic light scattering. We report the Grb7RA domain can exist in transient multimeric forms and, based upon modeling results, postulate the potential role of Grb7RA domain oligomerization in Grb7 function. Copyright © 2017 John Wiley & Sons, Ltd.

The adapter protein, Grb10, is a positive regulator of vascular endothelial growth factor signaling.

PubMed

Giorgetti-Peraldi, S; Murdaca, J; Mas, J C; Van Obberghen, E

2001-07-05

Vascular endothelial growth factor (VEGF) is an important regulator of vasculogenesis and angiogenesis. Activation of VEGF receptors leads to the recruitment of SH2 containing proteins which link the receptors to the activation of signaling pathways. Here we report that Grb10, an adapter protein of which the biological role remains unknown, is tyrosine phosphorylated in response to VEGF in endothelial cells (HUVEC) and in 293 cells expressing the VEGF receptor KDR. An intact SH2 domain is required for Grb10 tyrosine phosphorylation in response to VEGF, and this phosphorylation is mediated in part through the activation of Src. In HUVEC, VEGF increases Grb10 mRNA level. Expression of Grb10 in HUVEC or in KDR expressing 293 cells results in an increase in the amount and in the tyrosine phosphorylation of KDR. In 293 cells, this is correlated with the activation of signaling molecules, such as MAP kinase. By expressing mutants of Grb10, we found that the positive action of Grb10 is independent of its SH2 domain. Moreover, these Grb10 effects on KDR seem to be specific since Grb10 has no effect on the insulin receptor, and Grb2, another adapter protein, does not mimic the effect of Grb10 on KDR. In conclusion, we propose that VEGF up-regulates Grb10 level, which in turn increases KDR molecules, suggesting that Grb10 could be involved in a positive feedback loop in VEGF signaling.

Implications of the radio and X-ray emission that followed GW170817

NASA Astrophysics Data System (ADS)

Nakar, Ehud; Piran, Tsvi

2018-04-01

The radio and X-rays that followed GW170817 increased gradually over ˜ 100 days, resembling the radio flare predicted to arise from the interaction of a binary neutron star merger outflow with the ISM (Nakar & Piran 2011). Considering a blast wave moving with a Lorentz factor Γ, we show that an off-axis observer, namely an observer at θobs > 1/Γ, sees a light curve rising faster than Fν∝t3. Therefore, the observed rise, Fν∝ t0.78, implies that at all times we have seen an on-axis emission. Namely, the emitting matter was within θobs < 1/Γ at the time of observations (even if it was off-axis beforehand). The observations tightly constrain the blast wave Lorentz factor: Γ ˜ (1.5 - 7)(t/10 day)-0.21. The isotropic equivalent energy in the observed region increases with time, Eiso ˜ 1050 erg (t/150 day)1.3, implying that the outflow was structured. This structure could have different origins, however, the only physically motivated one, proposed so far, is the interaction of a relativistic jet with the ejecta and the resulting cocoon. The jet could have been choked or successful. In the latter case, it has produced a short GRB pointing elsewhere (this successful jet-cocoon system is sometimes called a "structured jet"). Although circumstantial evidence disfavors a successful jet, the jet fate cannot be decisively determined from current observations. The light curve alone may not be sufficient to resolve this question, since both chocked and successful jets can lead to a gradual rise to a peak, followed by a decay. Therefore, the recent turnover of the light curve does not necessitate a successful jet.

Grb7 is over-expressed in cervical cancer and facilitate invasion and inhibit apoptosis in cervical cancer cells.

PubMed

Zhao, Hong-Bing; Zhang, Xi-Feng; Jia, Xue-Lin; Wang, Hao-Bin

2017-09-01

Growth factor receptor bound protein-7 (Grb7) is a multi-domain adaptor protein that is co-opted by numerous tyrosine kinases involved in various cellular signaling. The objective of this study was to investigate the expression of Grb7 and its clinicopathological significance in cervical cancer. Utilising immunohistochemical staining, we examined the expression of Grb7 in 120 cases of human cervical cancer tissue and 10 cases of adjacent non-cancerous cervical tissue. The positive rate of Grb7 protein expression was 34.2%, which was significantly higher than that in adjacent non-cancerous cervical tissue (0%, p<0.05). The expression of Grb7 was found to be correlated with age, tumor size, serosal invasion, differentiated degree, tumor stage, early or advanced stage and lymph node metastasis. Kaplan-Meier survival analysis showed that patients with positive Grb7 protein expression had a lower overall survival rate than patients without Grb7 expression. In addition, Grb7 plays an important role in promoting tumor progression, including invasion and anti-apoptosis, in cervical cancer cell line. Down-regulation of Grb7 repressed the expression of MMP-9 and Bcl-2, and increased the expression of Bax in Grb7 knockdown Hela cells. Cell invasion assay showed decreased number of Grb7 knockdown Hela cells (18.7±2.1) compared to Hela cells (65.3±2.5, P<0.05). Our results indicated that Grb7 over-expression may facilitate invasion and inhibit apoptosis in cervical cancer and Grb7 is a potentially molecular target of cervical cancer chemotherapy. Copyright © 2017 Elsevier GmbH. All rights reserved.

Measurement of the Shape of the Optical-IR Spectrum of Prompt Emission from Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Grossan, Bruce; Kistaubayev, M.; Smoot, G.; Scherr, L.

2017-06-01

While the afterglow phase of gamma-ray bursts (GRBs) has been extensively measured, detections of prompt emission (i.e. during bright X-gamma emission) are more limited. Some prompt optical measurements are regularly made, but these are typically in a single wide band, with limited time resolution, and no measurement of spectral shape. Some models predict a synchrotron self-absorption spectral break somewhere in the IR-optical region. Measurement of the absorption frequency would give extensive information on each burst, including the electron Lorentz factor, the radius of emission, and more (Shen & Zhang 2008). Thus far the best prompt observations have been explained invoking a variety of models, but often with a non-unique interpretation. To understand this apparently heterogeneous behavior, and to reduce the number of possible models, it is critical to add data on the optical - IR spectral shape.Long GRB prompt X-gamma emission typically lasts ~40-80 s. The Swift BAT instrument rapidly measures GRB positions to within a few arc minutes and communicates them via the internet within a few seconds. We have measured the time for a fast-moving D=700 mm telescope to point and settle to be less than 9 s anywhere on the observable sky. Therefore, the majority of prompt optical-IR emission can be measured responding to BAT positions with this telescope. In this presentation, we describe our observing and science programs, and give our design for the Burst Simultaneous Three-channel Instrument (BSTI), which uses dichroics to send eparate bands to 3 cameras. Two EMCCD cameras, give high-time resolution in B and V; a third camera with a HgCdTe sensor covers H band, allowing us to study extinguished bursts. For a total exposure time of 10 s, we find a 5 sigma sensitivity of 21.3 and 20.3 mag in B and R for 1" seeing and Kitt Peak sky brightness, much fainter than typical previous prompt detections. We estimate 5 sigma H-band sensitivity for an IR optimized telescope to be ~16.9 mag in 20 s. With three channels broadly separated in wavelength, two separate slopes would be measured, or if present between our bands, the absorption frequency would be determined, a brand-new window into GRB physics.

Classifying GRB 170817A/GW170817 in a Fermi duration-hardness plane

NASA Astrophysics Data System (ADS)

Horváth, I.; Tóth, B. G.; Hakkila, J.; Tóth, L. V.; Balázs, L. G.; Rácz, I. I.; Pintér, S.; Bagoly, Z.

2018-03-01

GRB 170817A, associated with the LIGO-Virgo GW170817 neutron-star merger event, lacks the short duration and hard spectrum of a Short gamma-ray burst (GRB) expected from long-standing classification models. Correctly identifying the class to which this burst belongs requires comparison with other GRBs detected by the Fermi GBM. The aim of our analysis is to classify Fermi GRBs and to test whether or not GRB 170817A belongs—as suggested—to the Short GRB class. The Fermi GBM catalog provides a large database with many measured variables that can be used to explore gamma-ray burst classification. We use statistical techniques to look for clustering in a sample of 1298 gamma-ray bursts described by duration and spectral hardness. Classification of the detected bursts shows that GRB 170817A most likely belongs to the Intermediate, rather than the Short GRB class. We discuss this result in light of theoretical neutron-star merger models and existing GRB classification schemes. It appears that GRB classification schemes may not yet be linked to appropriate theoretical models, and that theoretical models may not yet adequately account for known GRB class properties. We conclude that GRB 170817A may not fit into a simple phenomenological classification scheme.

A neutron-star-driven X-ray flash associated with supernova SN 2006aj.

PubMed

Mazzali, Paolo A; Deng, Jinsong; Nomoto, Ken'ichi; Sauer, Daniel N; Pian, Elena; Tominaga, Nozomu; Tanaka, Masaomi; Maeda, Keiichi; Filippenko, Alexei V

2006-08-31

Supernovae connected with long-duration gamma-ray bursts (GRBs) are hyper-energetic explosions resulting from the collapse of very massive stars ( approximately 40 M\\circ, where M\\circ is the mass of the Sun) stripped of their outer hydrogen and helium envelopes. A very massive progenitor, collapsing to a black hole, was thought to be a requirement for the launch of a GRB. Here we report the results of modelling the spectra and light curve of SN 2006aj (ref. 9), which demonstrate that the supernova had a much smaller explosion energy and ejected much less mass than the other GRB-supernovae, suggesting that it was produced by a star whose initial mass was only approximately 20 M\\circ. A star of this mass is expected to form a neutron star rather than a black hole when its core collapses. The smaller explosion energy of SN 2006aj is matched by the weakness and softness of GRB 060218 (an X-ray flash), and the weakness of the radio flux of the supernova. Our results indicate that the supernova-GRB connection extends to a much broader range of stellar masses than previously thought, possibly involving different physical mechanisms: a 'collapsar' (ref. 8) for the more massive stars collapsing to a black hole, and magnetic activity of the nascent neutron star for the less massive stars.

The sub-energetic gamma-ray burst GRB 031203 as a cosmic analogue to the nearby GRB 980425.

PubMed

Soderberg, A M; Kulkarni, S R; Berger, E; Fox, D W; Sako, M; Frail, D A; Gal-Yam, A; Moon, D S; Cenko, S B; Yost, S A; Phillips, M M; Persson, S E; Freedman, W L; Wyatt, P; Jayawardhana, R; Paulson, D

2004-08-05

Over the six years since the discovery of the gamma-ray burst GRB 980425, which was associated with the nearby (distance approximately 40 Mpc) supernova 1998bw, astronomers have debated fiercely the nature of this event. Relative to bursts located at cosmological distance (redshift z approximately 1), GRB 980425 was under-luminous in gamma-rays by three orders of magnitude. Radio calorimetry showed that the explosion was sub-energetic by a factor of 10. Here we report observations of the radio and X-ray afterglow of the recent GRB 031203 (refs 5-7), which has a redshift of z = 0.105. We demonstrate that it too is sub-energetic which, when taken together with the low gamma-ray luminosity, suggests that GRB 031203 is the first cosmic analogue to GRB 980425. We find no evidence that this event was a highly collimated explosion viewed off-axis. Like GRB 980425, GRB 031203 appears to be an intrinsically sub-energetic gamma-ray burst. Such sub-energetic events have faint afterglows. We expect intensive follow-up of faint bursts with smooth gamma-ray light curves (common to both GRB 031203 and 980425) to reveal a large population of such events.

The First Pulse of the Extremely Bright GRB 130427A: A Test Lab for Synchrotron Shocks

NASA Technical Reports Server (NTRS)

Preece, R.; Burgess, J. Michael; von Kienlin, A.; Bhat, P. N.; Briggs, M. S.; Byrne, D.; Chaplin, V.; Cleveland, W.; Collazzi, A. C.; Goldstein, A.;

A search for Fermi bursts associated with supernovae and their frequency of occurrence

NASA Astrophysics Data System (ADS)

Kovacevic, M.; Izzo, L.; Wang, Y.; Muccino, M.; Della Valle, M.; Amati, L.; Barbarino, C.; Enderli, M.; Pisani, G. B.; Li, L.

2014-09-01

Context. Observations suggest that most long duration gamma-ray bursts (GRBs) are connected with broad-line supernovae Ib/c, (SNe-Ibc). The presence of GRB-SNe is revealed by rebrightenings emerging from the optical GRB afterglow 10-15 days, in the rest-frame of the source, after the prompt GRB emission. Aims: Fermi/GBM has a field of view (FoV) about 6.5 times larger than the FoV of Swift, therefore we expect that a number of GRB-SN connections have been missed because of lack of optical and X-ray instruments on board of Fermi, which are essential for revealing SNe associated with GRBs. This has motivated our search in the Fermi catalog for possible GRB-SN events. Methods: The search for possible GRB-SN associations follows two requirements: (1) SNe should fall inside the Fermi/GBM error box of the considered long GRB, and (2) this GRB should occur within 20 days before the SN event. Results: We have found five cases within z< 0.2 fulfilling the above reported requirements. One of them, GRB 130702A-SN 2013dx, was already known to have a GRB-SN association. We have analyzed the remaining four cases and we have concluded that three of them are, very likely, just random coincidences due to the Fermi/GBM large error box associated with each GRB detection. We found one GRB possibly associated with a SN 1998bw-like source, GRB 120121B/SN 2012ba. Conclusions: The very low redshift of GRB 120121B/SN 2012ba (z = 0.017) implies a low isotropic energy of this burst (Eiso = 1.39 × 1048) erg. We then compute the rate of Fermi low-luminosity GRBs connected with SNe to be ρ0,b ≤ 770 Gpc-3 yr-1. We estimate that Fermi/GBM could detect 1-4 GRBs-SNe within z ≤ 0.2 in the next 4 years.

Dissecting GRB7-mediated signals for proliferation and migration in HER2 overexpressing breast tumor cells: GTP-ase rules.

PubMed

Pradip, De; Bouzyk, Mark; Dey, Nandini; Leyland-Jones, Brian

2013-01-01

Amplification of human Her2 and its aberrant signaling in 20-30% of early breast cancer patients is responsible for highly aggressive tumors with poor outcome. Grb7 is reported to be co-amplified with Her2. We report a concurrent high expression of mRNA (from FFPE tumor samples; mRNA correlation, Pearson r(2)= 0.806), and high levels of GRB7 protein (immunoblot) in HER2+ breast cancer cell lines. We demonstrated the signaling mechanism of HER2 and downstream effectors that contributes to proliferation and migration. Using HER2+ and trastuzumab-resistant breast cancer cell lines, we identified the interaction between GRB7 and HER2 in the control of HER2+ cell proliferation. Our co-IP data show that GRB7 recruits SHC into the HER2-GRB7 signaling complex. This complex formation leads to activation of RAS-GTP. We also observed that following integrin engagement, GRB7 is phosphorylated at tyrosine in a p-FAK (Y397) dependent manner. This FAK-GRB7 complex leads to downstream activation of RAC1-GTP (responsible for migration) probably through the recruitment of VAV2. Our CO-IP data demonstrate that GRB7 directly binds with VAV2 following fibronectin engagement in HER2+ cells. To address whether GRB7 could serve as a pathway specific therapeutic target, we used siRNA to suppress GRB7 expression. Knockdown of GRB7 expression in the HER2+ breast cancer cell lines decreases RAS activation, cell proliferation, 2D and 3D colony formation and also blocked integrin-mediated RAC1 activation along with integrin-directed cell migration. These findings dissected the HER2-mediated signaling cascade into (1) HER2+ cell proliferation (HER2-GRB7-SHC-RAS) and (2) HER2+ cell migration (alpha5 beta1/alpha4 beta1-FAK-GRB7-VAV2-RAC1). Our data clearly demonstrate that a coupling of GRB7 with HER2 is required for the proliferative and migratory signals in HER2+ breast tumor cells.

Molecular Cloning and Characterization of Growth Factor Receptor Bound-Protein in Clonorchis sinensis

PubMed Central

Bai, Xuelian; Lee, Ji-Yun; Kim, Tae Im; Dai, Fuhong; Lee, Tae-Jin; Hong, Sung-Jong

2014-01-01

Background Clonorchis sinensis causes clonorchiasis, a potentially serious disease. Growth factor receptor-bound protein 2 (Grb2) is a cytosolic protein conserved among animals and plays roles in cellular functions such as meiosis, organogenesis and energy metabolism. In the present study, we report first molecular characters of growth factor receptor bound-protein (CsGrb2) from C. sinensis as counter part of Grb2 from animals and its possible functions in development and organogenesis of C. sinensis. Methodology/Principal Findings A CsGrb2 cDNA clone retrieved from the C. sinensis transcriptome encoded a polypeptide with a SH3-SH2-SH3 structure. Recombinant CsGrb2 was bacterially produced and purified to homogeneity. Native CsGrb2 with estimated molecular weight was identified from C. sinensis adult extract by western blotting using a mouse immune serum to recombinant CsGrb2. CsGrb2 transcripts was more abundant in the metacercariae than in the adults. Immunohistochemical staining showed that CsGrb2 was localized to the suckers, mesenchymal tissues, sperms in seminal receptacle and ovary in the adults, and abundantly expressed in most organs of the metacercariae. Recombinant CsGrb2 was evaluated to be little useful as a serodiagnostic reagent for C. sinesis human infections. Conclusion Grb2 protein found in C. sinensis was conserved among animals and suggested to play a role in the organogenesis, energy metabolism and mitotic spermatogenesis of C. sinensis. These findings from C. sinensis provide wider understanding on diverse function of Grb2 in lower animals such as platyhelminths. PMID:24454892

Preparation of crystals for characterizing the Grb7 SH2 domain before and after complex formation with a bicyclic peptide antagonist.

PubMed

Ambaye, Nigus D; Gunzburg, Menachem J; Traore, Daouda A K; Del Borgo, Mark P; Perlmutter, Patrick; Wilce, Matthew C J; Wilce, Jacqueline A

2014-02-01

Human growth factor receptor-bound protein 7 (Grb7) is an adapter protein involved in cell growth, migration and proliferation. It is now recognized that Grb7 is an emerging therapeutic target in specific cancer subtypes. Recently, the discovery of a bicyclic peptide inhibitor that targets the Grb7 SH2 domain, named G7-B1, was reported. In an attempt to probe the foundation of its interaction with Grb7, the crystallization and preliminary data collection of both the apo and G7-B1-bound forms of the Grb7 SH2 domain are reported here. Diffraction-quality crystals were obtained using the hanging-drop vapour-diffusion method. After several rounds of microseeding, crystals of the apo Grb7 SH2 domain were obtained that diffracted to 1.8 Å resolution, while those of the G7-B1-Grb7 SH2 domain complex diffracted to 2.2 Å resolution. The apo Grb7 SH2 domain crystallized in the trigonal space group P63, whereas the G7-B1-Grb7 SH2 domain complex crystallized in the monoclinic space group P21. The experimental aspects of crystallization, crystal optimization and data collection and the preliminary data are reported.

Scientific prospects for spectroscopy of the gamma-ray burst prompt emission with SVOM

NASA Astrophysics Data System (ADS)

Bernardini, M. G.; Xie, F.; Sizun, P.; Piron, F.; Dong, Y.; Atteia, J.-L.; Antier, S.; Daigne, F.; Godet, O.; Cordier, B.; Wei, J.

2017-10-01

SVOM (Space-based multi-band astronomical Variable Objects Monitor) is a Sino-French space mission dedicated to the study of Gamma-Ray Bursts (GRBs) in the next decade, capable to detect and localise the GRB emission, and to follow its evolution in the high-energy and X-ray domains, and in the visible and NIR bands. The satellite carries two wide-field high-energy instruments: a coded-mask gamma-ray imager (ECLAIRs; 4-150 keV), and a gamma-ray spectrometer (GRM; 15-5500 keV) that, together, will characterise the GRB prompt emission spectrum over a wide energy range. In this paper we describe the performances of the ECLAIRs and GRM system with different populations of GRBs from existing catalogues, from the classical ones to those with a possible thermal component superimposed to their non-thermal emission. The combination of ECLAIRs and the GRM will provide new insights also on other GRB properties, as for example the spectral characterisation of the subclass of short GRBs showing an extended emission after the initial spike.

GRO: Black hole models for gamma-ray bursts

NASA Technical Reports Server (NTRS)

Ruderman, Malvin

1995-01-01

The Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) has established that the distribution of gamma-ray bursts (GRB's) is isotropic but is bound radially. This finding suggests that the bursts are either cosmological or they originate from an extended Galactic halo. The implied luminosities and the observed variability of the GRB's on time scales as short as one millisecond suggest that they originate from compact objects. We are presently studying black hole models for GRB's. Any such model must produce a non-thermal photon spectrum to agree with the observed properties. For a wide range of burst parameters the assumed bursting source consists of a non-thermal electron-positron-photon plasma of very high density. It seems possible to produce such a plasma in accretion onto black holes. In our on-going work, we are developing the kinetic theory for a non-equilibrium pair plasma. The main new features of our work are as follows: (1) We do not assume the presence of a thermal electron bath. (2) Non-thermal, high-energy pairs are allowed to have an arbitrary concentration and energy distribution. (3) There is no soft photon source in our model; initially all the photons in the plasma are either energetic X-rays or gamma-rays. (4) The initial energy distribution of the pairs as well as photons is arbitrary. (5) We collect the analytical expressions for the kinetic kernels for all relevant processes. And (6) we present a different approach to finding the time-evolution of pair and photon spectra, which is a combination of the kinetic-theory and the non-linear Monte-Carlo schemes. We have developed many Monte-Carlo programs to model various process, to take into account the time evolution, and to incorporate various physical effects which are unique to non-thermal plasmas. The hydrodynamics of fireballs in GRB's was studied before. Applying results from kinetic theory will improve our understanding of these systems.

GRB 170817A: a short GRB seen off-axis

NASA Astrophysics Data System (ADS)

He, Xin-Bo; Tam, Pak-Hin Thomas; Shen, Rong-Feng

2018-04-01

The angular distribution of gamma-ray burst (GRB) jets is not yet clear. The observed luminosity of GRB 170817A is the lowest among all known short GRBs, which is best explained by the fact that our line of sight is outside of the jet opening angle, θ obs > θ j , where θ obs is the angle between our line of sight and the jet axis. As inferred by gravitational wave observations, as well as radio and X-ray afterglow modeling of GRB 170817A, it is likely that θ obs ∼ 20° – 28°. In this work, we quantitatively consider two scenarios of angular energy distribution of GRB ejecta: a top-hat jet and a structured jet with a power law index s. For the top-hat jet model, we get a large θ j (e.g., θ j > 10°), a rather high local (i.e., z < 0.01) short GRB rate ∼8–15×103, Gpc‑3, yr‑1 (estimated to be 90∼1850 Gpc‑3, yr‑1 in Fong et al.) and an extremely high E peak,0 (on-axis, rest-frame) > 7.5 × 104, keV (∼500, keV for a typical short GRB). For the structured jet model, we use θ obs to give limits on s and θj for typical on-axis luminosity of a short GRB (e.g., 1049 erg s‑1 ∼ 1051 erg s‑1), and a low on-axis luminosity case (e.g., 1049 erg s‑1) gives more reasonable values of s. The structured jet model is more feasible for GRB 170817A than the top-hat jet model due to the rather high local short GRB rate, and the extremely high on-axis E peak,0 almost rules out the top-hat jet model. GRB 170817A is likely a low on-axis luminosity GRB (1049 erg s‑1) with a structured jet.

Development of binding assays for the SH2 domain of Grb7 and Grb2 using fluorescence polarization.

PubMed

Luzy, Jean-Philippe; Chen, Huixiong; Gril, Brunilde; Liu, Wang-Qing; Vidal, Michel; Perdereau, Dominique; Burnol, Anne-Françoise; Garbay, Christiane

2008-02-01

Adaptor proteins Grb7 and Grb2 have been implicated as being 2 potential therapeutic targets in several human cancers, especially those that overexpress ErbB2. These 2 proteins contain both a SH2 domain (Src homology 2) that binds to phosphorylated tyrosine residues contained within ErbB2 and other specific protein targets. Two assays based on enzyme-linked immunosorbent assay and fluorescence polarization methods have been developed and validated to find and rank inhibitors for both proteins binding to the pY(1139). Fluorescence polarization assays allowed the authors to determine quickly and reproducibly affinities of peptides from low nanomolar to high micromolar range and to compare them directly for Grb7 and Grb2. As a result, the assays have identified a known peptidomimetic Grb2 SH2 inhibitor (mAZ-pTyr-(alphaMe)pTyr-Asn-NH(2)) that exhibits the most potent affinity for the Grb7 SH2 domain described to date.

Growth factor receptor-binding protein 10 (Grb10) as a partner of phosphatidylinositol 3-kinase in metabolic insulin action.

PubMed

Deng, Youping; Bhattacharya, Sujoy; Swamy, O Rama; Tandon, Ruchi; Wang, Yong; Janda, Robert; Riedel, Heimo

2003-10-10

The regulation of the metabolic insulin response by mouse growth factor receptor-binding protein 10 (Grb10) has been addressed in this report. We find mouse Grb10 to be a critical component of the insulin receptor (IR) signaling complex that provides a functional link between IR and p85 phosphatidylinositol (PI) 3-kinase and regulates PI 3-kinase activity. This regulatory mechanism parallels the established link between IR and p85 via insulin receptor substrate (IRS) proteins. A direct association was demonstrated between Grb10 and p85 but was not observed between Grb10 and IRS proteins. In addition, no effect of mouse Grb10 was observed on the association between IRS-1 and p85, on IRS-1-associated PI 3-kinase activity, or on insulin-mediated activation of IR or IRS proteins. A critical role of mouse Grb10 was observed in the regulation of PI 3-kinase activity and the resulting metabolic insulin response. Dominant-negative Grb10 domains, in particular the SH2 domain, eliminated the metabolic response to insulin in differentiated 3T3-L1 adipocytes. This was consistently observed for glycogen synthesis, glucose and amino acid transport, and lipogenesis. In parallel, the same metabolic responses were substantially elevated by increased levels of Grb10. A similar role of Grb10 was confirmed in mouse L6 cells. In addition to the SH2 domain, the Pro-rich amino-terminal region of Grb10 was implicated in the regulation of PI 3-kinase catalytic activity. These regulatory roles of Grb10 were extended to specific insulin mediators downstream of PI 3-kinase including PKB/Akt, glycogen synthase kinase, and glycogen synthase. In contrast, a regulatory role of Grb10 in parallel insulin response pathways including p70 S6 kinase, ubiquitin ligase Cbl, or mitogen-activated protein kinase p38 was not observed. The dissection of the interaction of mouse Grb10 with p85 and the resulting regulation of PI 3-kinase activity should help elucidate the complexity of the IR signaling mechanism.

Patient-derived Hormone-naive Prostate Cancer Xenograft Models Reveal Growth Factor Receptor Bound Protein 10 as an Androgen Receptor-repressed Gene Driving the Development of Castration-resistant Prostate Cancer.

PubMed

Hao, Jun; Ci, Xinpei; Xue, Hui; Wu, Rebecca; Dong, Xin; Choi, Stephen Yiu Chuen; He, Haiqing; Wang, Yu; Zhang, Fang; Qu, Sifeng; Zhang, Fan; Haegert, Anne M; Gout, Peter W; Zoubeidi, Amina; Collins, Colin; Gleave, Martin E; Lin, Dong; Wang, Yuzhuo

2018-06-01

Although androgen deprivation therapy is initially effective in controlling growth of hormone-naive prostate cancers (HNPCs) in patients, currently incurable castration-resistant prostate cancer (CRPC) inevitably develops. To identify CRPC driver genes that may provide new targets to enhance CRPC therapy. Patient-derived xenografts (PDXs) of HNPCs that develop CRPC following host castration were examined for changes in expression of genes at various time points after castration using transcriptome profiling analysis; particular attention was given to pre-CRPC changes in expression indicative of genes acting as potential CRPC drivers. The functionality of a potential CRPC driver was validated via its knockdown in cultured prostate cancer cells; its clinical relevance was established using data from prostate cancer patient databases. Eighty genes were found to be significantly upregulated at the CRPC stage, while seven of them also showed elevated expression prior to CRPC development. Among the latter, growth factor receptor bound protein 10 (GRB10) was the most significantly and consistently upregulated gene. Moreover, elevated GRB10 expression in clinical prostate cancer samples correlated with more aggressive tumor types and poorer patient treatment outcome. GRB10 knockdown markedly reduced prostate cancer cell proliferation and activity of AKT, a well-established CRPC mediator. A positive correlation between AKT activity and GRB10 expression was also found in clinical cohorts. GRB10 acts as a driver of CRPC and sensitizes androgen receptor pathway inhibitors, and hence GRB10 targeting provides a novel therapeutic strategy for the disease. Development of castration-resistant prostate cancer (CRPC) is a major problem in the management of the disease. Using state-of-the-art patient-derived hormone-naive prostate cancer xenograft models, we found and validated the growth factor receptor bound protein 10 gene as a driver of CRPC, indicating that it may be used as a new molecular target to enhance current CRPC therapy. Copyright © 2018 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Allostery Mediates Ligand Binding to Grb2 Adaptor in a Mutually Exclusive Manner

PubMed Central

McDonald, Caleb B.; El Hokayem, Jimmy; Zafar, Nawal; Balke, Jordan E.; Bhat, Vikas; Mikles, David C.; Deegan, Brian J.; Seldeen, Kenneth L.; Farooq, Amjad

2012-01-01

Allostery plays a key role in dictating the stoichiometry and thermodynamics of multi-protein complexes driving a plethora of cellular processes central to health and disease. Herein, using various biophysical tools, we demonstrate that although Sos1 nucleotide exchange factor and Gab1 docking protein recognize two non-overlapping sites within the Grb2 adaptor, allostery promotes the formation of two distinct pools of Grb2-Sos1 and Grb2-Gab1 binary signaling complexes in concert in lieu of a composite Sos1-Grb2-Gab1 ternary complex. Of particular interest is the observation that the binding of Sos1 to the nSH3 domain within Grb2 sterically blocks the binding of Gab1 to the cSH3 domain and vice versa in a mutually exclusive manner. Importantly, the formation of both the Grb2-Sos1 and Grb2-Gab1 binary complexes is governed by a stoichiometry of 2:1, whereby the respective SH3 domains within Grb2 homodimer bind to Sos1 and Gab1 via multivalent interactions. Collectively, our study sheds new light on the role of allostery in mediating cellular signaling machinery. PMID:23334917

Broadband Study of GRB 091127: A Sub-Energetic Burst at Higher Redshift?

NASA Technical Reports Server (NTRS)

Troja, E.; Sakamoto, T.; Guidorzi, C.; Norris, J. P.; Panaitescu, A.; Kobayashi, S.; Omodei, N.; Brown, J. C.; Burrows, D. N.; Evans, P. A.;

ORIGIN: Metal Creation and Evolution From The Cosmic Dawn

NASA Astrophysics Data System (ADS)

Piro, L.; den Herder, J. W.; Ohashi, T.; Hartmann, D. H.; Kouveliotou, C.

2011-08-01

ORIGIN is a mission designed to use Gamma-Ray Bursts as a unique probe to study the cosmic history of baryons and the metal enrichment from the first stars up to the present Universe. Reconstructing the cosmic history of metals, from the first population of stars to the processes involved in the formation of galaxies and clusters of galaxies, is a key observational challenge. Observing any single star in the early Universe is in fact beyond the reach of presently planned mission. By measuring GRB redshifts and abundances in the circumburst medium deep into the era of re-ionization (z>6), ORIGIN will discover when star formation started and how it evolved into the present day structures. ORIGIN will collect 400 GRBs per year covering the full redshift distribution. About twice per month a GRB from the re-ionization era will trigger the instruments. The resulting multi-element abundance patterns derived from high resolution X-ray and IR observations will map the evolving chemical composition of the early Universe, ``fingerprint'' the elusive PopIII stars, and constrain the shape of the Initial Mass Function (IMF) of the first stars. While not observing GRB afterglows, ORIGIN will map element abundances in local structures (z<2) by determining the properties of the hot IGM in clusters and groups of galaxies and the Warm-Hot Intergalactic Medium (WHIM). In this paper we focus on the use of GRB to track the earliest star populations.

The First Pulse of the Extremely Bright GRB 130427A: A Test Lab for Synchrotron Shocks

DOE PAGES

Preece, R.; Burgess, J. Michael; von Kienlin, A.; ...

2013-11-21

Gamma-ray burst (GRB) 130427A is one of the most energetic GRBs ever observed. The initial pulse up to 2.5 seconds is possibly the brightest well-isolated pulse observed to date. A fine time resolution spectral analysis shows power-law decays of the peak energy from the onset of the pulse, consistent with models of internal synchrotron shock pulses. But, a strongly correlated power-law behavior is observed between the luminosity and the spectral peak energy that is inconsistent with curvature effects arising in the relativistic outflow. We found it difficult for any of the existing models to account for all of the observedmore » spectral and temporal behaviors simultaneously.« less

Hydrodynamics of Gamma-Ray Burst Afterglow

NASA Astrophysics Data System (ADS)

Sari, Re'em

1997-11-01

The detection of delayed emission at X-ray optical and radio wavelengths (``afterglow'') following gamma-ray bursts (GRBs) suggests that the relativistic shell that emitted the initial GRB as the result of internal shocks decelerates on encountering an external medium, giving rise to the afterglow. We explore the interaction of a relativistic shell with a uniform interstellar medium (ISM) up to the nonrelativistic stage. We demonstrate the importance of several effects that were previously ignored and must be included in a detailed radiation analysis. At a very early stage (few seconds), the observed bolometric luminosity increases as t2. On longer timescales (more than ~10 s), the luminosity drops as t-1. If the main burst is long enough, an intermediate stage of constant luminosity will form. In this case, the afterglow overlaps the main burst; otherwise there is a time separation between the two. On the long timescale, the flow decelerates in a self-similar way, reaching nonrelativistic velocities after ~30 days. Explicit expressions for the radial profiles of this self-similar deceleration are given. As a result of the deceleration and the accumulation of ISM material, the relation between the observed time, the shock radius, and its Lorentz factor is given by t=R/16γ2c, which is a factor of 8 different from the usual expression. We show that even though only a small fraction of the internal energy is given to the electrons, most of the energy can be radiated over time. If the fraction of energy in electrons is greater than ~10%, radiation losses will significantly influence the hydrodynamical evolution at early times (less than ~1 day).

A Tale of Two Faint Bursts: GRB 050223 and GRB 050911

NASA Astrophysics Data System (ADS)

Page, K. L.; Barthelmy, S. D.; Beardmore, A. P.; Burrows, D. N.; Campana, S.; Chincharini, G.; Cummings, J. R.; Cusumano, G.; Gehrels, N.; Giommi, P.; Goad, M. R.; Godet, O.; Graham, J.; Kaneko, Y.; Kennea, J. A.; Mangano, V.; Markwardt, C. B.; O'Brien, P. T.; Osborne, J. P.; Reichart, D. E.; Rol, E.; Sakamoto, T.; Tagliaferri, G.; Tanvir, N. R.; Wells, A. A.; Zhang, B.

2006-05-01

GRBs 050223 and 050911 were discovered by the Swift Burst Alert Telescope (BAT) on 23rd February and 11th September 2005 respectively. The observation of GRB 050223 showed a faint, fading X-ray source, which was identified as the afterglow; GRB 050911, however, was not detected, making any X-ray afterglow extremely faint. The faintness of the afterglow of GRB 050223 could be explained by a large opening or viewing angle, or by the burst being at high redshift. The non-detection of GRB 050911 may indicate the burst occurred in a low-density environment, or, alternatively, was due to a compact object merger, in spite of the apparent long duration of the burst.

A New GRB follow-up Software at TUG

NASA Astrophysics Data System (ADS)

Dindar, M.; Parmaksizoglu, M.; Helhel, S.; Esenoglu, H.; Kirbiyik, H.

2016-12-01

A gamma-ray burst (GRB) optical photometric follow-up system at TUBITAK (Scientic and Technological Research Council of Turkey) National Observatory (TUG) has been planned. It uses the 0.6 m Telescope (T60) and can automatically respond to GRB Coordinates Network (GCN) alerts. The telescopes slew relatively fast, being able to point to a new target field within 30 s upon a request. Whenever available, the 1 m T100 and 2.5 m RTT150 telescopes will be used in the future. As an example in 2015, the GRB software system (will be server side) at T60-telescope responded to GRB alert and started the observation as early as 129 s after the GRB trigger autonomously.

Molecular targeting of growth factor receptor-bound 2 (Grb2) as an anti-cancer strategy.

PubMed

Dharmawardana, Pathirage G; Peruzzi, Benedetta; Giubellino, Alessio; Burke, Terrence R; Bottaro, Donald P

2006-01-01

Growth factor receptor-bound 2 (Grb2) is a ubiquitously expressed adapter protein that provides a critical link between cell surface growth factor receptors and the Ras signaling pathway. As such, it has been implicated in the oncogenesis of several important human malignancies. In addition to this function, research over the last decade has revealed other fundamental roles for Grb2 in cell motility and angiogenesis--processes that also contribute to tumor growth, invasiveness and metastasis. This functional profile makes Grb2 a high priority target for anti-cancer drug development. Knowledge of Grb2 protein structure, its component Src homology domains and their respective structure-function relationships has facilitated the rapid development of sophisticated drug candidates that can penetrate cells, bind Grb2 with high affinity and potently antagonize Grb2 signaling. These novel compounds offer considerable promise in our growing arsenal of rationally designed anti-cancer therapeutics.

VizieR Online Data Catalog: GRB prompt emission fitted with the DREAM model (Ahlgren+, 2015)

NASA Astrophysics Data System (ADS)

Ahlgren, B.; Larsson, J.; Nymark, T.; Ryde, F.; Pe'Er, A.

2018-01-01

We illustrate the application of the DREAM model by fitting it to two different, bright Fermi GRBs; GRB 090618 and GRB 100724B. While GRB 090618 is well fitted by a Band function, GRB 100724B was the first example of a burst with a significant additional BB component (Guiriec et al. 2011ApJ...727L..33G). GRB 090618 is analysed using Gamma-ray Burst Monitor (GBM) data (Meegan et al. 2009ApJ...702..791M) from the NaI and BGO detectors. For GRB 100724B, we used GBM data from the NaI and BGO detectors as well as Large Area Telescope Low Energy (LAT-LLE) data. For both bursts we selected NaI detectors seeing the GRB at an off-axis angle lower than 60° and the BGO detector as being the best aligned of the two BGO detectors. The spectra were fitted in the energy ranges 8-1000 keV (NaI), 200-40000 keV (BGO) and 30-1000 MeV (LAT-LLE). (2 data files).

Lorentz, the Solvay Councils and the Physics Institute

NASA Astrophysics Data System (ADS)

Berends, Frits A.

2015-09-01

This paper describes the crucial role which Lorentz played in shaping and continuing the Solvay Councils and the Physics Institute. At the same time it will become clear that Lorentz* intensive involvement in these activities added significantly to his influence on, and recognition in, the international physics community. The first Solvay Council in 1911 was an initiative of the German physical chemist Walther Nernst. It was generously supported by the wealthy industrialist and philantropist Ernest Solvay. About five months before the Council*s start Nernst invited Lorentz to chair the meeting. That was no simple task in view of the fundamental problem of the quanta and the practical problem of communication in different languages. Lorentz*s way of presiding the conference impressed all participants. When, after the meeting, Solvay was willing to support research in the field, it was only natural to ask Lorentz for a plan. Within two months Lorentz provided Solvay with a draft which would serve as an outline for the statutes of an institute. The international Solvay Institute of Physics was founded on 1 May 1912. It would support research proposals in a specified field and would regularly organize Councils. An international scientific committee would decide on grants which could be requested from everywhere. Between the Institute*s beginnings and the outbreak of WWI, 97 requests were considered and 40 proposals - originating from 7 countries - were accepted. A second Council took place in 1913. Lorentz was given the possibility to spend considerable time on chairing the scientific committee when in 1912 his full time professorship in Leiden was changed into a part-time one. During WWI Lorentz maintained contacts with Solvay and with several of his foreign colleagues in the countries at war. He tried to remain objective, impartial and helpful, and did not lose hope that pre-war international scientific relations would eventually be re-established. After the war he had to accept the Allied exclusion of the scientists of the Central Powers, but considered this a temporary necessity which should be lifted as soon as possible. He therefore advocated the continuation of the Solvay Physics Institute. At the time, this idea was far from obvious, but it was endorsed by Solvay. After two Councils without participants from the Central Powers the administrative committee decided in 1926 to lift this exclusion for the fifth Council, and to accept the idea of inviting Einstein to become a member of the scientific committee. This happened after a visit of Lorentz to King Albert in order to explain the intentions of the committee. Thus, the way was paved for a truly international Council in 1927.

Time-resolved GRB spectra in the complex radiation of synchrotron and Compton processes

NASA Astrophysics Data System (ADS)

Jiang, Y. G.; Hu, S. M.; Chen, X.; Li, K.; Guo, D. F.; Li, Y. T.; Li, H. Z.; Zhao, Y. Y.; Lin, H. N.; Chang, Z.

2016-03-01

Under the steady-state condition, the spectrum of electrons is investigated by solving the continuity equation under the complex radiation of both the synchrotron and Compton processes. The resulted gamma-ray burst (GRB) spectrum is a broken power law in both the fast and slow cooling phases. On the basis of this electron spectrum, the spectral indices of the Band function in four different phases are presented. In the complex radiation frame, the detail investigation on physical parameters reveals that three models can answer the α ˜ -1 problem, which are the synchrotron plus synchrotron self-Compton in the internal and the external shock models, and the synchrotron plus the external Compton processes in the external shock model. A possible marginal to fast cooling phase transition in GRB 080916C is discussed. The time-resolved spectra in different main pulses of GRB 100724B, GRB 100826A and GRB 130606B are investigated. We found that the flux is proportional to the peak energy in almost all main pulses. A significant (5σ) correlation for Fp ˜ Ep is evident the first main pulse of GRB 100826A, and three marginally significant (3σ) correlations Fp ˜ Ep are found in main pulses of GRB 100826A and GRB 130606B. The correlation between spectral index and Ep at 3 ˜ 4σ level are observed in the first main pulse of GRB 100826A. Such correlations are possible explained in the complex radiation scenario.

Short GRBs: Opening Angles, Local Neutron Star Merger Rate, and Off-axis Events for GRB/GW Association

NASA Astrophysics Data System (ADS)

Jin, Zhi-Ping; Li, Xiang; Wang, Hao; Wang, Yuan-Zhu; He, Hao-Ning; Yuan, Qiang; Zhang, Fu-Wen; Zou, Yuan-Chuan; Fan, Yi-Zhong; Wei, Da-Ming

2018-04-01

The jet breaks in the afterglow light curves of short gamma-ray bursts (SGRBs), rarely detected so far, are crucial for estimating the half-opening angles of the ejecta (θ j) and hence the neutron star merger rate. In this work, we report the detection of jet decline behaviors in GRB 150424A and GRB 160821B, and find θ j ∼ 0.1 rad. Together with five events reported before 2015 and three others “identified” recently (GRB 050709, GRB 060614, and GRB 140903A), we have a sample consisting of nine SGRBs and one long-short GRB with reasonably estimated θ j. In particular, three Swift bursts in the sample have redshifts z ≤ 0.2, with which we estimate the local neutron star merger rate density to be ∼ {1109}-657+1432 {Gpc}}-3 {yr}}-1 or {162}-83+140 {Gpc}}-3 {yr}}-1 if the narrowly beamed GRB 061201 is excluded. Inspired by the typical θ j ∼ 0.1 rad found currently, we further investigate whether the off-beam GRBs (in the uniform jet model) or the off-axis events (in the structured jet model) can significantly enhance the GRB/GW association. For the former, the enhancement is at most moderate, while for the latter the enhancement can be much greater and a high GRB/GW association probability of ∼10% is possible. We also show that the data of GRB 160821B may contain a macronova/kilonova emission component with a temperature of ∼3100 K at ∼3.6 days after the burst and more data are needed to ultimately clarify.

Recruitment of the Adaptor Protein Grb2 to EGFR Tetramers

PubMed Central

2015-01-01

Adaptor protein Grb2 binds phosphotyrosines in the epidermal growth factor (EGF) receptor (EGFR) and thereby links receptor activation to intracellular signaling cascades. Here, we investigated how recruitment of Grb2 to EGFR is affected by the spatial organization and quaternary state of activated EGFR. We used the techniques of image correlation spectroscopy (ICS) and lifetime-detected Förster resonance energy transfer (also known as FLIM-based FRET or FLIM–FRET) to measure ligand-induced receptor clustering and Grb2 binding to activated EGFR in BaF/3 cells. BaF/3 cells were stably transfected with fluorescently labeled forms of Grb2 (Grb2–mRFP) and EGFR (EGFR–eGFP). Following stimulation of the cells with EGF, we detected nanometer-scale association of Grb2–mRFP with EGFR–eGFP clusters, which contained, on average, 4 ± 1 copies of EGFR–eGFP per cluster. In contrast, the pool of EGFR–eGFP without Grb2–mRFP had an average cluster size of 1 ± 0.3 EGFR molecules per punctum. In the absence of EGF, there was no association between EGFR–eGFP and Grb2–mRFP. To interpret these data, we extended our recently developed model for EGFR activation, which considers EGFR oligomerization up to tetramers, to include recruitment of Grb2 to phosphorylated EGFR. The extended model, with adjustment of one new parameter (the ratio of the Grb2 and EGFR copy numbers), is consistent with a cluster size distribution where 2% of EGFR monomers, 5% of EGFR dimers, <1% of EGFR trimers, and 94% of EGFR tetramers are associated with Grb2. Together, our experimental and modeling results further implicate tetrameric EGFR as the key signaling unit and call into question the widely held view that dimeric EGFR is the predominant signaling unit. PMID:24697349

GRB2 Interaction with the Ecotropic Murine Leukemia Virus Receptor, mCAT-1, Controls Virus Entry and Is Stimulated by Virus Binding

PubMed Central

Chen, Zeming; Kolokoltsov, Andrey A.; Wang, Jia; Adhikary, Shramika; Lorinczi, Marta; Elferink, Lisa A.

2012-01-01

For retroviruses such as HIV-1 and murine leukemia virus (MLV), active receptor recruitment and trafficking occur during viral entry. However, the underlying mechanisms and cellular factors involved in the process are largely uncharacterized. The viral receptor for ecotropic MLV (eMLV), a classical model for retrovirus infection mechanisms and pathogenesis, is mouse cationic amino acid transporter 1 (mCAT-1). Growth factor receptor-bound protein 2 (GRB2) is an adaptor protein that has been shown to couple cell surface receptors, such as epidermal growth factor receptor (EGFR) and hepatocyte growth factor receptor, to intracellular signaling events. Here we examined if GRB2 could also play a role in controlling infection by retroviruses by affecting receptor function. The GRB2 RNA interference (RNAi)-mediated suppression of endogenous GRB2 resulted in a consistent and significant reduction of virus binding and membrane fusion. The binding between eMLV and cells promoted increased GRB2–mCAT-1 interactions, as detected by immunoprecipitation. Consistently, the increased colocalization of GRB2 and mCAT-1 signals was detected by confocal microscopy. This association was time dependent and paralleled the kinetics of cell-virus membrane fusion. Interestingly, unlike the canonical binding pattern seen for GRB2 and growth factor receptors, GRB2–mCAT-1 binding does not depend on the GRB2-SH2 domain-mediated recognition of tyrosine phosphorylation on the receptor. The inhibition of endogenous GRB2 led to a reduction in surface levels of mCAT-1, which was detected by immunoprecipitation and by a direct binding assay using a recombinant MLV envelope protein receptor binding domain (RBD). Consistent with this observation, the expression of a dominant negative GRB2 mutant (R86K) resulted in the sequestration of mCAT-1 from the cell surface into intracellular vesicles. Taken together, these findings suggest a novel role for GRB2 in ecotropic MLV entry and infection by facilitating mCAT-1 trafficking. PMID:22090132

GRB2 interaction with the ecotropic murine leukemia virus receptor, mCAT-1, controls virus entry and is stimulated by virus binding.

PubMed

Chen, Zeming; Kolokoltsov, Andrey A; Wang, Jia; Adhikary, Shramika; Lorinczi, Marta; Elferink, Lisa A; Davey, Robert A

2012-02-01

For retroviruses such as HIV-1 and murine leukemia virus (MLV), active receptor recruitment and trafficking occur during viral entry. However, the underlying mechanisms and cellular factors involved in the process are largely uncharacterized. The viral receptor for ecotropic MLV (eMLV), a classical model for retrovirus infection mechanisms and pathogenesis, is mouse cationic amino acid transporter 1 (mCAT-1). Growth factor receptor-bound protein 2 (GRB2) is an adaptor protein that has been shown to couple cell surface receptors, such as epidermal growth factor receptor (EGFR) and hepatocyte growth factor receptor, to intracellular signaling events. Here we examined if GRB2 could also play a role in controlling infection by retroviruses by affecting receptor function. The GRB2 RNA interference (RNAi)-mediated suppression of endogenous GRB2 resulted in a consistent and significant reduction of virus binding and membrane fusion. The binding between eMLV and cells promoted increased GRB2-mCAT-1 interactions, as detected by immunoprecipitation. Consistently, the increased colocalization of GRB2 and mCAT-1 signals was detected by confocal microscopy. This association was time dependent and paralleled the kinetics of cell-virus membrane fusion. Interestingly, unlike the canonical binding pattern seen for GRB2 and growth factor receptors, GRB2-mCAT-1 binding does not depend on the GRB2-SH2 domain-mediated recognition of tyrosine phosphorylation on the receptor. The inhibition of endogenous GRB2 led to a reduction in surface levels of mCAT-1, which was detected by immunoprecipitation and by a direct binding assay using a recombinant MLV envelope protein receptor binding domain (RBD). Consistent with this observation, the expression of a dominant negative GRB2 mutant (R86K) resulted in the sequestration of mCAT-1 from the cell surface into intracellular vesicles. Taken together, these findings suggest a novel role for GRB2 in ecotropic MLV entry and infection by facilitating mCAT-1 trafficking.

THE PROPERTIES OF THE 2175 A EXTINCTION FEATURE DISCOVERED IN GRB AFTERGLOWS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zafar, Tayyaba; Watson, Darach; Eliasdottir, Ardis

The unequivocal, spectroscopic detection of the 2175 A bump in extinction curves outside the Local Group is rare. To date, the properties of the bump have been examined in only two gamma-ray burst (GRB) afterglows (GRB 070802 and GRB 080607). In this work, we analyze in detail the detections of the 2175 Angstrom-Sign extinction bump in the optical spectra of two further GRB afterglows: GRB 080605 and 080805. We gather all available optical/near-infrared photometric, spectroscopic, and X-ray data to construct multi-epoch spectral energy distributions (SEDs) for both GRB afterglows. We fit the SEDs with the Fitzpatrick and Massa model withmore » a single or broken power law. We also fit a sample of 38 GRB afterglows, known to prefer a Small Magellanic Cloud (SMC)-type extinction curve, with the same model. We find that the SEDs of GRB 080605 and GRB 080805 at two epochs are fit well with a single power law with a derived extinction of A{sub V} = 0.52{sup +0.13}{sub -0.16} and 0.50{sup +0.13}{sub -0.10}, and 2.1{sup +0.7}{sub -0.6} and 1.5 {+-} 0.2, respectively. While the slope of the extinction curve of GRB 080805 is not well constrained, the extinction curve of GRB 080605 has an unusual very steep far-UV rise together with the 2175 A bump. Such an extinction curve has previously been found in only a small handful of sightlines in the Milky Way. One possible explanation of such an extinction curve may be dust arising from two different regions with two separate grain populations, however we cannot distinguish the origin of the curve. We finally compare the four 2175 A bump sightlines to the larger GRB afterglow sample and to Local Group sightlines. We find that while the width and central positions of the bumps are consistent with what is observed in the Local Group, the relative strength of the detected bump (A{sub bump}) for GRB afterglows is weaker for a given A{sub V} than for almost any Local Group sightline. Such dilution of the bump strength may offer tentative support to a dual dust-population scenario.« less

Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph and FORS2 spectroscopy of the GRB 081008 afterglow

NASA Astrophysics Data System (ADS)

D'Elia, V.; Campana, S.; Covino, S.; D'Avanzo, P.; Piranomonte, S.; Tagliaferri, G.

2011-11-01

We aim at studying the gamma-ray burst (GRB), GRB 081008, environment by analysing the spectra of its optical afterglow. Ultraviolet and Visual Echelle Spectrograph/Very Large Telescope (UVES/VLT) high-resolution spectroscopy of GRB 081008 was secured ˜5 h after the Swift-BAT trigger. Our data set also comprises three VLT/FORS2 nearly simultaneous spectra of the same source. The availability of nearly simultaneous high- and low-resolution spectra for a GRB afterglow is an extremely rare event. The GRB-damped Lyman α system at z= 1.9683 shows that the interstellar medium (ISM) of the host galaxy is constituted by at least three components which contribute to the line profiles. Component I is the redmost one, and is 20 and 78 km s-1 redward components II and III, respectively. We detect several ground state and excited absorption features in components I and II. These features have been used to compute the distances between the GRB and the absorbers. Component I is found to be 52 ± 6 pc away from the GRB, while component II presents few excited transitions and its distance is 200+60- 80 pc. Component III only features a few, low-ionization and saturated lines suggesting that it is even farther from the GRB. Component I represents the closest absorber ever detected near a GRB. This (relatively) low distance can possibly be a consequence of a dense GRB environment, which prevents the GRB prompt/afterglow emission to strongly affect the ISM up to higher distances. The hydrogen column density associated with GRB 081008 is log NH/cm-2= 21.11 ± 0.10, and the metallicity of the host galaxy is in the range of [X/H] =-1.29 to -0.52. In particular, we found [Fe/H] =-1.19 ± 0.11 and [Zn/H] =-0.52 ± 0.11 with respect to solar values. This discrepancy can be explained by the presence of dust in the GRB ISM, given the opposite refractory properties of iron and zinc. By deriving the depletion pattern for GRB 081008, we find the optical extinction in the visual band to be AV˜ 0.19 mag. The curve-of-growth analysis applied to the FORS2 spectra brings column densities consistent at the 3σ level to that evaluated from the UVES data using the line-fitting procedure. This reflects the low saturation of the detected GRB 081008 absorption features. Based on observations collected at the European Southern Observatory, ESO, the VLT/Kueyen telescope, Paranal, Chile, in the framework of the programme 082-0755.

The origin and location of the 5 March 1979 gamma-ray burst

NASA Technical Reports Server (NTRS)

Kazanas, Demosthenes

1988-01-01

Evidence and arguments concerning the origin and location of the gamma-ray burst (GRB) of March 5, 1979 are reviewed. This GRB has been positionally identified with the SNR 49 in the LMC. Such an association would fix the GRB's distance at 55 kpc, and the observed flux from the GRB would require prodigious energy and luminosity, casting doubt on the GRB's distance and its association with the LMC. Some Kosmos 856 observations which may provide more direct evidence on the energy released are discussed.

Broadband Study of GRB 091127: A Sub-energetic Burst at Higher Redshift?

NASA Astrophysics Data System (ADS)

Troja, E.; Sakamoto, T.; Guidorzi, C.; Norris, J. P.; Panaitescu, A.; Kobayashi, S.; Omodei, N.; Brown, J. C.; Burrows, D. N.; Evans, P. A.; Gehrels, N.; Marshall, F. E.; Mawson, N.; Melandri, A.; Mundell, C. G.; Oates, S. R.; Pal'shin, V.; Preece, R. D.; Racusin, J. L.; Steele, I. A.; Tanvir, N. R.; Vasileiou, V.; Wilson-Hodge, C.; Yamaoka, K.

2012-12-01

GRB 091127 is a bright gamma-ray burst (GRB) detected by Swift at a redshift z = 0.49 and associated with SN 2009nz. We present the broadband analysis of the GRB prompt and afterglow emission and study its high-energy properties in the context of the GRB/SN association. While the high luminosity of the prompt emission and standard afterglow behavior are typical of cosmological long GRBs, its low-energy release (E γ < 3 × 1049 erg), soft spectrum, and unusual spectral lag connect this GRB to the class of sub-energetic bursts. We discuss the suppression of high-energy emission in this burst, and investigate whether this behavior could be connected with the sub-energetic nature of the explosion.

A Reconnection Switch to Trigger gamma-Ray Burst Jet Dissipation

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKinney, Jonathan C.; Uzdensky, Dmitri A.

2012-03-14

Prompt gamma-ray burst (GRB) emission requires some mechanism to dissipate an ultrarelativistic jet. Internal shocks or some form of electromagnetic dissipation are candidate mechanisms. Any mechanism needs to answer basic questions, such as what is the origin of variability, what radius does dissipation occur at, and how does efficient prompt emission occur. These mechanisms also need to be consistent with how ultrarelativistic jets form and stay baryon pure despite turbulence and electromagnetic reconnection near the compact object and despite stellar entrainment within the collapsar model. We use the latest magnetohydrodynamical models of ultrarelativistic jets to explore some of these questionsmore » in the context of electromagnetic dissipation due to the slow collisional and fast collisionless reconnection mechanisms, as often associated with Sweet-Parker and Petschek reconnection, respectively. For a highly magnetized ultrarelativistic jet and typical collapsar parameters, we find that significant electromagnetic dissipation may be avoided until it proceeds catastrophically near the jet photosphere at large radii (r {approx} 10{sup 13}-10{sup 14}cm), by which the jet obtains a high Lorentz factor ({gamma} {approx} 100-1000), has a luminosity of L{sub j} {approx} 10{sup 50}-10{sup 51} erg s{sup -1}, has observer variability timescales of order 1s (ranging from 0.001-10s), achieves {gamma}{theta}{sub j} {approx} 10-20 (for opening half-angle {theta}{sub j}) and so is able to produce jet breaks, and has comparable energy available for both prompt and afterglow emission. A range of model parameters are investigated and simplified scaling laws are derived. This reconnection switch mechanism allows for highly efficient conversion of electromagnetic energy into prompt emission and associates the observed prompt GRB pulse temporal structure with dissipation timescales of some number of reconnecting current sheets embedded in the jet. We hope this work helps motivate the development of self-consistent radiative compressible relativistic reconnection models.« less

Laser-Induced Skyrmion Writing and Erasing in an Ultrafast Cryo-Lorentz Transmission Electron Microscope

NASA Astrophysics Data System (ADS)

Berruto, G.; Madan, I.; Murooka, Y.; Vanacore, G. M.; Pomarico, E.; Rajeswari, J.; Lamb, R.; Huang, P.; Kruchkov, A. J.; Togawa, Y.; LaGrange, T.; McGrouther, D.; Rønnow, H. M.; Carbone, F.

2018-03-01

We demonstrate that light-induced heat pulses of different duration and energy can write Skyrmions in a broad range of temperatures and magnetic field in FeGe. Using a combination of camera-rate and pump-probe cryo-Lorentz transmission electron microscopy, we directly resolve the spatiotemporal evolution of the magnetization ensuing optical excitation. The Skyrmion lattice was found to maintain its structural properties during the laser-induced demagnetization, and its recovery to the initial state happened in the sub-μ s to μ s range, depending on the cooling rate of the system.

Developmental Programming Mediated by Complementary Roles of Imprinted Grb10 in Mother and Pup

PubMed Central

Cowley, Michael; Garfield, Alastair S.; Madon-Simon, Marta; Charalambous, Marika; Clarkson, Richard W.; Smalley, Matthew J.; Kendrick, Howard; Isles, Anthony R.; Parry, Aled J.; Carney, Sara; Oakey, Rebecca J.; Heisler, Lora K.; Moorwood, Kim; Wolf, Jason B.; Ward, Andrew

2014-01-01

Developmental programming links growth in early life with health status in adulthood. Although environmental factors such as maternal diet can influence the growth and adult health status of offspring, the genetic influences on this process are poorly understood. Using the mouse as a model, we identify the imprinted gene Grb10 as a mediator of nutrient supply and demand in the postnatal period. The combined actions of Grb10 expressed in the mother, controlling supply, and Grb10 expressed in the offspring, controlling demand, jointly regulate offspring growth. Furthermore, Grb10 determines the proportions of lean and fat tissue during development, thereby influencing energy homeostasis in the adult. Most strikingly, we show that the development of normal lean/fat proportions depends on the combined effects of Grb10 expressed in the mother, which has the greater effect on offspring adiposity, and Grb10 expressed in the offspring, which influences lean mass. These distinct functions of Grb10 in mother and pup act complementarily, which is consistent with a coadaptation model of imprinting evolution, a model predicted but for which there is limited experimental evidence. In addition, our findings identify Grb10 as a key genetic component of developmental programming, and highlight the need for a better understanding of mother-offspring interactions at the genetic level in predicting adult disease risk. PMID:24586114

Panchromatic Observations of GRB 110205A and Other GRB Optical Prompt Observations Obtained by ROTSE

NASA Astrophysics Data System (ADS)

Zheng, Weikang; with a larger Collaboration

2011-09-01

The leading radiation mechanisms for gamma-ray bursts (GRBs), as predicted by the standard GRB fireball model, include synchrotron radiation, synchrotron self-Compton (SSC), and inverse Compton scattering from thermal photons. Panchromatic observations during GRB prompt emission are important to distinguish the mechanisms. GRB 110205A, triggered by Swift, is also detected by Suzaku, ROTSE-IIIb and BOOTES telescopes when the GRB is still radiating gamma-rays. These panchromatic observations, covering 6 orders of energy range from 1 eV to 5 MeV, will be presented. We clearly discover an interesting two-break energy spectrum for the first time, roughly consistent with the synchrotron spectrum predicted by the standard GRB fireball model. The two break energies can be explained as νc, the synchrotron cooling frequency, and νm, the synchrotron typical frequency. With a sample of GRBs with optical prompt detections from ROTSE observations, one can also constrain the self-absorption frequency, νa. These detailed prompt observations are important to discriminate different mechanisms and thus lead us to a better and deeper understanding of the GRB fireball model. This research is supported by the NASA grant NNX08AV63G and the NSF grant PHY-0801007.

DISCOVERY OF SN 2009nz ASSOCIATED WITH GRB 091127

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobb, B. E.; Bloom, J. S.; Perley, D. A.

2010-08-01

We report SMARTS, Gemini, and Swift-UVOT observations of the optical transient (OT) associated with gamma-ray burst (GRB) 091127, at redshift 0.49, taken between 0.9 hr and 102 days following the Swift trigger. In our early-time observations, the OT fades in a manner consistent with previously observed GRB afterglows. However, after nine days post-burst, the OT is observed to brighten for a period of {approx}two weeks, after which the source resumes fading. A comparison of this late-time 'bump' to SN 1998bw (the broad-lined Type Ic supernova associated with GRB 980425), and several other GRB supernovae (SNe), indicates that the most straightforwardmore » explanation is that GRB 091127 was accompanied by a contemporaneous SN (SN 2009nz) that peaked at a magnitude of M{sub V} = -19.0 {+-} 0.2. SN 2009nz is globally similar to other GRB SNe, but evolves slightly faster than SN 1998bw and reaches a slightly dimmer peak magnitude. We also analyze the early-time UV-optical-IR spectral energy distribution of the afterglow of GRB 091127 and find that there is little to no reddening in the host galaxy along the line of sight to this burst.« less

BATSE Observations of Gamma-Ray Burst Tails

NASA Technical Reports Server (NTRS)

Connaughton, Valerie

2002-01-01

With the observation of low-energy radiation coming from the site of gamma-ray bursts in the hours to weeks after the initial gamma ray burst, it appears that astronomers have discovered a cosmological imprint made by the burster on its surroundings. This paper discusses the phenomenon of postburst emission in Burst and Transient Source Experiment (BATSE) gamma-ray bursts at energies usually associated with prompt emission. After summing up the background-subtracted signals from hundreds of bursts, it is found that tails out to hundreds of seconds after the trigger could be a common feature of events of a duration greater than 2 seconds, and perhaps of the shorter bursts at a lower and shorter-lived level. The tail component may be softer and seems independent of the duration (within the long-GRB sample) and brightness of the prompt burst emission. Some individual bursts have visible tails at gamma-ray energies, and the spectrum in a few cases differs from that of the prompt emission. For one of these bursts, GRB 991216, afterglow at lower energies was detected, which raised the possibility of seeing afterglow observations over large energy ranges using the next generation of GRB detectors in addition to sensitive space- or ground-based telescopes.

GRB110721A: An Extreme Peak Energy and Signatures of the Photosphere

NASA Technical Reports Server (NTRS)

Axelsson, M.; Baldini, L.; Barbiellini, G.; Baring, M. G.; Bellazzini, R.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Caliandro, G. A.;

Gamma-ray bursts and their use as cosmic probes

PubMed Central

2017-01-01

Since the launch of the highly successful and ongoing Swift mission, the field of gamma-ray bursts (GRBs) has undergone a revolution. The arcsecond GRB localizations available within just a few minutes of the GRB alert has signified the continual sampling of the GRB evolution through the prompt to afterglow phases revealing unexpected flaring and plateau phases, the first detection of a kilonova coincident with a short GRB, and the identification of samples of low-luminosity, ultra-long and highly dust-extinguished GRBs. The increased numbers of GRB afterglows, GRB-supernova detections, redshifts and host galaxy associations has greatly improved our understanding of what produces and powers these immense, cosmological explosions. Nevertheless, more high-quality data often also reveal greater complexity. In this review, I summarize some of the milestones made in GRB research during the Swift era, and how previous widely accepted theoretical models have had to adapt to accommodate the new wealth of observational data. PMID:28791158

Broad band simulation of Gamma Ray Bursts (GRB) prompt emission in presence of an external magnetic field

NASA Astrophysics Data System (ADS)

Ziaeepour, Houri; Gardner, Brian

2011-12-01

The origin of prompt emission in GRBs is not yet well understood. The simplest and most popular model is Synchrotron Self-Compton (SSC) emission produced by internal shocks inside an ultra-relativistic jet. However, recent observations of a delayed high energy component by the Fermi-LAT instrument have encouraged alternative models. Here we use a recently developed formulation of relativistic shocks for GRBs to simulate light curves and spectra of synchrotron and self-Compton emissions in the framework of internal shock model. This model takes into account the evolution of quantities such as densities of colliding shells, and fraction of kinetic energy transferred to electrons and to induced magnetic field. We also extend this formulation by considering the presence of a precessing external magnetic field. These simulations are very realistic and present significant improvement with respect to previous phenomenological GRB simulations. They reproduce light curves of separate peaks of real GRBs and variety of spectral slopes at E > Epeak observed by the Fermi-LAT instrument. The high energy emission can be explained by synchrotron emission and a subdominant contribution from inverse Compton. We also suggest an explanation for extended tail emission and relate it to the screening of the magnetic field and/or trapping of accelerated electrons in the electromagnetic energy structure of the plasma in the shock front. Spectral slopes of simulated bursts at E << Epeak are consistent with theoretical prediction and at E < Epeak can be flatter if the spectrum of electrons is roughly flat or has a shallow slope at low energies. The observed flat spectra at soft gamma-ray and hard x-ray bands is the evidence that there is a significant contribution at E < Epeak from lower Lorentz factor wing of electron distribution which have a roughly random acceleration rather than being thermal. This means that the state of matter in the jet at the time of ejection is most probably nonthermal. As for the effect of a precessing external magnetic field, we show that due to the fast variation of other quantities, its signature in the Power Distribution Spectrum (PDS) is significantly suppressed and only when the duration of the burst is few times longer than the oscillation period it can be detected, otherwise either it is confused with the Poisson noise or with intrinsic variations of the emission. Therefore, low significant oscillations observed in the PDS of GRB 090709a are most probably due to a precessing magnetic field.

Spectral evolution of GRBs with negative spectral lag using Fermi GBM observations

NASA Astrophysics Data System (ADS)

Chakrabarti, Arundhati; Chaudhury, Kishor; Sarkar, Samir K.; Bhadra, Arunava

2018-06-01

The positive spectral lag of Gamma Ray Bursts (GRBs) is often explained in terms of hard-to-soft spectral evolution of GRB pulses. While positive lags of GRBs is very common, there are few GRB pulses that exhibits negative spectral lags. In the present work we examine whether negative lags of GRBs also can be interpreted in terms of spectral evolution of GRB pulses or not. Using Fermi-GBM data, we identify two GRBs, GRB 090426C and GRB 150213A, with clean pulses that exhibit negative spectral lag. An indication of soft to hard transition has been noticed for the negative spectral lag events from the spectral evolution study. The implication of the present findings on the models of GRB spectral lags are discussed.

Broadband Study of GRB 091127: A Sub-Energetic Burst at Higher Redshift?

DOE PAGES

Troja, E.; Sakamoto, T.; Guidorzi, C.; ...

2012-11-21

GRB 091127 is a bright gamma-ray burst (GRB) detected by Swift at a redshift z = 0.49 and associated with SN 2009nz. In this paper, we present the broadband analysis of the GRB prompt and afterglow emission and study its high-energy properties in the context of the GRB/SN association. While the high luminosity of the prompt emission and standard afterglow behavior are typical of cosmological long GRBs, its low-energy release (E γ < 3 x 10 49 erg), soft spectrum, and unusual spectral lag connect this GRB to the class of sub-energetic bursts. Finally, we discuss the suppression of high-energymore » emission in this burst, and investigate whether this behavior could be connected with the sub-energetic nature of the explosion.« less

The Nck family of adapter proteins: regulators of actin cytoskeleton.

PubMed

Buday, László; Wunderlich, Livius; Tamás, Peter

2002-09-01

SH2/SH3 domain-containing adapter proteins, such as the Nck family, play a major role in regulating tyrosine kinase signalling. They serve to recruit proline-rich effector molecules to tyrosine-phosphorylated kinases or their substrates. Initially, it was not clear why cells from nematodes to vertebrates contain redundant and closely related SH2/SH3 adapters, such as Grb2, Crk and Nck. Recent evidence suggests that their biological roles are clearly different, whereas, for example, Grb2 connects activated receptor tyrosine kinases to Sos and Ras, leading to cell proliferation. The proteins of Nck family are implicated in organisation of actin cytoskeleton, cell movement or axon guidance in flies. In this review, the author attempts to summarise signalling pathways in which Nck plays a critical role.

Highly-ionized metals as probes of the circumburst gas in the natal regions of gamma-ray bursts

NASA Astrophysics Data System (ADS)

Heintz, K. E.; Watson, D.; Jakobsson, P.; Fynbo, J. P. U.; Bolmer, J.; Arabsalmani, M.; Cano, Z.; Covino, S.; D'Elia, V.; Gomboc, A.; Japelj, J.; Kaper, L.; Krogager, J.-K.; Pugliese, G.; Sánchez-Ramírez, R.; Selsing, J.; Sparre, M.; Tanvir, N. R.; Thöne, C. C.; de Ugarte Postigo, A.; Vergani, S. D.

2018-06-01

We present here a survey of high-ionization absorption lines in the afterglow spectra of long-duration gamma-ray bursts (GRBs) obtained with the VLT/X-shooter spectrograph. Our main goal is to investigate the circumburst medium in the natal regions of GRBs. Our primary focus is on the N V λλ 1238,1242 line transitions, but we also discuss other high-ionization lines such as O VI, C IV and Si IV. We find no correlation between the column density of N V and the neutral gas properties such as metallicity, H I column density and dust depletion, however the relative velocity of N V, typically a blueshift with respect to the neutral gas, is found to be correlated with the column density of H I. This may be explained if the N V gas is part of an H II region hosting the GRB, where the region's expansion is confined by dense, neutral gas in the GRB's host galaxy. We find tentative evidence (at 2σ significance) that the X-ray derived column density, NH, X, may be correlated with the column density of N V, which would indicate that both measurements are sensitive to the column density of the gas located in the vicinity of the GRB. We investigate the scenario where N V (and also O VI) is produced by recombination after the corresponding atoms have been stripped entirely of their electrons by the initial prompt emission, in contrast to previous models where highly-ionized gas is produced by photoionization from the GRB afterglow.

A recombined fusion protein PTD-Grb2-SH2 inhibits the proliferation of breast cancer cells in vitro.

PubMed

Yin, Jikai; Cai, Zhongliang; Zhang, Li; Zhang, Jian; He, Xianli; Du, Xilin; Wang, Qing; Lu, Jianguo

2013-03-01

The growth factor receptor bound protein 2 (Grb2) is one of the affirmative targets for cancer therapy, especially for breast cancer. In this study, we hypothesized the Src-homology 2 (SH2) domain in Grb2 may serve as a competitive protein-binding agent to interfere with the proliferation of breast cancer cells in vitro. We designed, constructed, expressed and purified a novel fusion protein containing the protein transduction domain (PTD) and Grb2-SH2 domain (we named it after PTD-Grb2-SH2). An immunofluorescence assay was used to investigate the location of PTD-Grb2-SH2 in cells. MTT assay and EdU experiments were applied to detect the proliferation of breast cancer cells. The ultra-structure was observed using transmission electron microscopy. Flow cytometry was used to determine the cytotoxicity of PTD-Grb2-SH2 on cell proliferation. We successfully obtained the PTD-Grb2-SH2 fusion protein in soluble form using a prokaryotic expression system. The new fusion protein successfully passed through both the cellular and nuclear membranes of breast cancer cells. The MTT assay showed that PTD-Grb2-SH2 exhibited significant toxicity to breast cancer cells in a dose- and time-dependent manner in vitro. EdU identified the decreased proliferation rates in treated MDA-MB-231 and SK-BR-3 cells. Observation by transmission electron microscopy and flow cytometry further confirmed the cytotoxicity as apoptosis. Our results show that the HIV1-TAT domain is a useful tool for transporting a low molecular weight protein across the cell membrane in vitro. The PTD-Grb2-SH2 may be a novel agent for breast cancer therapy.

Unexpected involvement of staple leads to redesign of selective bicyclic peptide inhibitor of Grb7

NASA Astrophysics Data System (ADS)

Gunzburg, Menachem J.; Kulkarni, Ketav; Watson, Gabrielle M.; Ambaye, Nigus D.; Del Borgo, Mark P.; Brandt, Rebecca; Pero, Stephanie C.; Perlmutter, Patrick; Wilce, Matthew C. J.; Wilce, Jacqueline A.

2016-06-01

The design of potent and specific peptide inhibitors to therapeutic targets is of enormous utility for both proof-of-concept studies and for the development of potential new therapeutics. Grb7 is a key signaling molecule in the progression of HER2 positive and triple negative breast cancers. Here we report the crystal structure of a stapled bicyclic peptide inhibitor G7-B1 in complex with the Grb7-SH2 domain. This revealed an unexpected binding mode of the peptide, in which the staple forms an alternative contact with the surface of the target protein. Based on this structural information, we designed a new series of bicyclic G7 peptides that progressively constrain the starting peptide, to arrive at the G7-B4 peptide that binds with an approximately 2-fold enhanced affinity to the Grb7-SH2 domain (KD = 0.83 μM) compared to G7-B1 and shows low affinity binding to Grb2-, Grb10- and Grb14-SH2 domains (KD > 100 μM). Furthermore, we determined the structure of the G7-B4 bicyclic peptide in complex with the Grb7-SH2 domain, both before and after ring closing metathesis to show that the closed staple is essential to the target interaction. The G7-B4 peptide represents an advance in the development of Grb7 inhibitors and is a classical example of structure aided inhibitor development.

Fermi-LAT observations of the gamma-ray burst GRB 130427A.

PubMed

Ackermann, M; Ajello, M; Asano, K; Atwood, W B; Axelsson, M; Baldini, L; Ballet, J; Barbiellini, G; Baring, M G; Bastieri, D; Bechtol, K; Bellazzini, R; Bissaldi, E; Bonamente, E; Bregeon, J; Brigida, M; Bruel, P; Buehler, R; Burgess, J Michael; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Cecchi, C; Chaplin, V; Charles, E; Chekhtman, A; Cheung, C C; Chiang, J; Chiaro, G; Ciprini, S; Claus, R; Cleveland, W; Cohen-Tanugi, J; Collazzi, A; Cominsky, L R; Connaughton, V; Conrad, J; Cutini, S; D'Ammando, F; de Angelis, A; DeKlotz, M; de Palma, F; Dermer, C D; Desiante, R; Diekmann, A; Di Venere, L; Drell, P S; Drlica-Wagner, A; Favuzzi, C; Fegan, S J; Ferrara, E C; Finke, J; Fitzpatrick, G; Focke, W B; Franckowiak, A; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gehrels, N; Germani, S; Gibby, M; Giglietto, N; Giles, M; Giordano, F; Giroletti, M; Godfrey, G; Granot, J; Grenier, I A; Grove, J E; Gruber, D; Guiriec, S; Hadasch, D; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Horan, D; Hughes, R E; Inoue, Y; Jogler, T; Jóhannesson, G; Johnson, W N; Kawano, T; Knödlseder, J; Kocevski, D; Kuss, M; Lande, J; Larsson, S; Latronico, L; Longo, F; Loparco, F; Lovellette, M N; Lubrano, P; Mayer, M; Mazziotta, M N; McEnery, J E; Michelson, P F; Mizuno, T; Moiseev, A A; Monzani, M E; Moretti, E; Morselli, A; Moskalenko, I V; Murgia, S; Nemmen, R; Nuss, E; Ohno, M; Ohsugi, T; Okumura, A; Omodei, N; Orienti, M; Paneque, D; Pelassa, V; Perkins, J S; Pesce-Rollins, M; Petrosian, V; Piron, F; Pivato, G; Porter, T A; Racusin, J L; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Ritz, S; Roth, M; Ryde, F; Sartori, A; Parkinson, P M Saz; Scargle, J D; Schulz, A; Sgrò, C; Siskind, E J; Sonbas, E; Spandre, G; Spinelli, P; Tajima, H; Takahashi, H; Thayer, J G; Thayer, J B; Thompson, D J; Tibaldo, L; Tinivella, M; Torres, D F; Tosti, G; Troja, E; Usher, T L; Vandenbroucke, J; Vasileiou, V; Vianello, G; Vitale, V; Winer, B L; Wood, K S; Yamazaki, R; Younes, G; Yu, H-F; Zhu, S J; Bhat, P N; Briggs, M S; Byrne, D; Foley, S; Goldstein, A; Jenke, P; Kippen, R M; Kouveliotou, C; McBreen, S; Meegan, C; Paciesas, W S; Preece, R; Rau, A; Tierney, D; van der Horst, A J; von Kienlin, A; Wilson-Hodge, C; Xiong, S; Cusumano, G; La Parola, V; Cummings, J R

2014-01-03

The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of these unique astrophysical sources. GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest γ-ray duration (20 hours), and one of the largest isotropic energy releases ever observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge the widely accepted model that the nonthermal high-energy emission in the afterglow phase of GRBs is synchrotron emission radiated by electrons accelerated at an external shock.

The First Unambiguous Electromagnetic Counterpart to a Gravitational-Wave Signal: GRB 170817A and GW170817

NASA Astrophysics Data System (ADS)

Goldstein, Adam

2018-01-01

On 2017 August 17 at 12:41:06 UTC the Fermi Gamma-ray Burst Monitor (GBM) detected and triggered on the short gamma-ray burst (GRB) 170817A. Approximately 2 s prior to this GRB, the LIGO gravitational-wave observatory triggered on a binary compact merger candidate associated with the GRB. This is the first unambiguous coincident observation of gravitational waves and electromagnetic radiation from a single astrophysical source and marks the start of gravitational-wave multi-messenger astronomy. We report the GBM observations and analysis of this short GRB and the joint science that results from this discovery.

Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A

DOE PAGES

Ackermann, M.; Ajello, M.; Asano, K.; ...

2013-11-21

The Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of these unique astrophysical sources using the observations of the exceptionally bright gamma-ray burst (GRB) 130427A. We found that GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest γ-ray duration (20 hours), and one of the largest isotropic energy releases ever observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge the widely accepted model that the nonthermal high-energy emission in the afterglow phase of GRBs is synchrotron emission radiated by electrons accelerated at an external shock.

Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A

NASA Technical Reports Server (NTRS)

Ackermann, M.; Ajello, M.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.;

GRB 060614: a Fake Short Gamma-Ray Burst

NASA Astrophysics Data System (ADS)

Caito, L.; Bernardini, M. G.; Bianco, C. L.; Dainotti, M. G.; Guida, R.; Ruffini, R.

2008-05-01

The explosion of GRB 060614 produced a deep break in the GRB scenario and opened new horizons of investigation because it can't be traced back to any traditional scheme of classification. In fact, it has features both of long bursts and of short bursts and, above all, it is the first case of long duration near GRB without any bright Ib/c associated Supernova. We will show that, in our canonical GRB scenario [1], this ``anomalous'' situation finds a natural interpretation and allows us to discuss a possible variation to the traditional classification scheme, introducing the distinction between ``genuine'' and ``fake'' short bursts.

GRB 060614: a progress report

NASA Astrophysics Data System (ADS)

Caito, L.; Bernardini, M. G.; Bianco, C. L.; Dainotti, M. G.; Guida, R.; Ruffini, R.

2008-01-01

The explosion of GRB 060614, detected by the Swift satellite, produced a deep break in the GRB scenario opening new horizons of investigation, because it can't be traced back to any traditional scheme of classification. In fact, it manifests peculiarities both of long bursts and of short bursts. Above all, it is the first case of long duration near GRB without any bright Ib/c associated Supernova. We will show that, in our canonical GRB scenario ([l]), this ``anomalous'' situation finds a natural interpretation and allows us to discuss a possible variation to the traditional classification scheme, introducing the distinction between ``genuine'' and ``fake'' short bursts.

Grb2 regulates B-cell maturation, B-cell memory responses and inhibits B-cell Ca2+ signalling.

PubMed

Ackermann, Jochen A; Radtke, Daniel; Maurberger, Anna; Winkler, Thomas H; Nitschke, Lars

2011-04-20

Grb2 is a ubiquitously expressed adaptor protein, which activates Ras and MAP kinases in growth factor receptor signalling, while in B-cell receptor (BCR) signalling this role is controversial. In B cell lines it was shown that Grb2 can inhibit BCR-induced Ca(2+) signalling. Nonetheless, the physiological role of Grb2 in primary B cells is still unknown. We generated a B-cell-specific Grb2-deficient mouse line, which had a severe reduction of mature follicular B cells in the periphery due to a differentiation block and decreased B-cell survival. Moreover, we found several changes in important signalling pathways: enhanced BCR-induced Ca(2+) signalling, alterations in mitogen-activated protein kinase activation patterns and strongly impaired Akt activation, the latter pointing towards a defect in PI3K signalling. Interestingly, B-cell-specific Grb2-deficient mice showed impaired IgG and B-cell memory responses, and impaired germinal centre formation. Thus, Grb2-dependent signalling pathways are crucial for lymphocyte differentiation processes, as well as for control of secondary humoral immune responses.

Probing the Nature of Short Swift Bursts via Deep INTEGRAL Monitoring of GRB 050925

NASA Technical Reports Server (NTRS)

Sakamoto, T.; Barbier, L.; Barthelmy, S. D.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.;

LFlGRB: Luminosity function of long gamma-ray bursts

NASA Astrophysics Data System (ADS)

Paul, Debdutta

2018-04-01

LFlGRB models the luminosity function (LF) of long Gamma Ray Bursts (lGRBs) by using a sample of Swift and Fermi lGRBs to re-derive the parameters of the Yonetoku correlation and self-consistently estimate pseudo-redshifts of all the bursts with unknown redshifts. The GRB formation rate is modeled as the product of the cosmic star formation rate and a GRB formation efficiency for a given stellar mass.

Optical GRB Afterglows Detected with UVOT

NASA Astrophysics Data System (ADS)

Marshall, F. E.

2008-05-01

The automated response of the UltraViolet and Optical Telescope (UVOT) on Swift to new GRBs has several parameters, including exposure time, filter sequence and data mode, that can be adjusted to optimize the science return of early afterglow observations. After some initial changes, the response has remained stable since March 15, 2006. From then through August 10, 2007, UVOT observed 122 of the 130 GRBs detected with Swift's Burst Alert Telescope (BAT). UVOT typically takes an initial 100-s exposure with the White filter (160-650 nm) starting 60-180 s after the trigger and then takes exposures with the other 6 filters. In its first finding chart exposure UVOT detected 39% of the 84 long (T90>2.0 s) GRBs that were not heavily reddened in the Milky Way (EB-V<0.5) and were observed within 500 seconds of the trigger. Another 4% were detected after including subsequent exposures. Afterglow magnitudes ranged from 12.8 to the sensitivity limit of ~21. Only 1 of 11 short GRBs were detected, and its magnitude was near the sensitivity limit. We also report correlations of afterglow magnitudes with other GRB properties.

Internal shocks in microquasar jets with a continuous Lorentz factor modulation

NASA Astrophysics Data System (ADS)

Pjanka, Patryk; Stone, James M.

2018-06-01

We perform relativistic hydrodynamic simulations of internal shocks formed in microquasar jets by continuous variation of the bulk Lorentz factor, in order to investigate the internal shock model. We consider one-, two-, and flicker noise 20-mode variability. We observe emergence of a forward-reverse shock structure for each peak of the Lorentz factor modulation. The high pressure in the shocked layer launches powerful outflows perpendicular to the jet beam into the ambient medium. These outflows dominate the details of the jet's kinetic energy thermalization. They are responsible for mixing between the jet and the surrounding medium and generate powerful shocks in the latter. These results do not concur with the popular picture of well-defined internal shells depositing energy as they collide within the confines of the jet, in fact collisions between internal shells themselves are quite rare in our continuous formulation of the problem. For each of our simulations, we calculate the internal energy deposited in the system, the `efficiency' of this deposition (defined as the ratio of internal to total flow energy), and the maximum temperature reached in order to make connections to emission mechanisms. We probe the dependence of these diagnostics on the Lorentz factor variation amplitudes, modulation frequencies, as well as the initial density ratio between the jet and the ambient medium.

An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi -GBM Detection of GRB 170817A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldstein, A.; Roberts, O. J.; Connaughton, V.

On 2017 August 17 at 12:41:06 UTC the Fermi Gamma-ray Burst Monitor (GBM) detected and triggered on the short gamma-ray burst (GRB) 170817A. Approximately 1.7 s prior to this GRB, the Laser Interferometer Gravitational-wave Observatory triggered on a binary compact merger candidate associated with the GRB. This is the first unambiguous coincident observation of gravitational waves and electromagnetic radiation from a single astrophysical source and marks the start of gravitational-wave multi-messenger astronomy. We report the GBM observations and analysis of this ordinary short GRB, which extraordinarily confirms that at least some short GRBs are produced by binary compact mergers.

An Ordinary Short Gamma-Ray Burst with Extraordinary Implications: Fermi-GBM Detection of GRB 170817A

NASA Astrophysics Data System (ADS)

Goldstein, A.; Veres, P.; Burns, E.; Briggs, M. S.; Hamburg, R.; Kocevski, D.; Wilson-Hodge, C. A.; Preece, R. D.; Poolakkil, S.; Roberts, O. J.; Hui, C. M.; Connaughton, V.; Racusin, J.; von Kienlin, A.; Dal Canton, T.; Christensen, N.; Littenberg, T.; Siellez, K.; Blackburn, L.; Broida, J.; Bissaldi, E.; Cleveland, W. H.; Gibby, M. H.; Giles, M. M.; Kippen, R. M.; McBreen, S.; McEnery, J.; Meegan, C. A.; Paciesas, W. S.; Stanbro, M.

2017-10-01

On 2017 August 17 at 12:41:06 UTC the Fermi Gamma-ray Burst Monitor (GBM) detected and triggered on the short gamma-ray burst (GRB) 170817A. Approximately 1.7 s prior to this GRB, the Laser Interferometer Gravitational-wave Observatory triggered on a binary compact merger candidate associated with the GRB. This is the first unambiguous coincident observation of gravitational waves and electromagnetic radiation from a single astrophysical source and marks the start of gravitational-wave multi-messenger astronomy. We report the GBM observations and analysis of this ordinary short GRB, which extraordinarily confirms that at least some short GRBs are produced by binary compact mergers.

The Swift Gamma-ray Burst Explorer: Early views into Black-hole Creation

NASA Technical Reports Server (NTRS)

Hill, Joe

2006-01-01

Swift has exceeded every pre-launch predicted advance in GRB science. It has discovered the farthest GRB ever seen and identified new GRBs at a rate of 100/year. It has also explored a brand new time interval in GRB light curves by revealing unpredicted phenomena of GRB flares and rapid x-ray afterglow declines. Swift has conducted 20,00o successful slews to sources and is predicted to stay in orbit until 2022.

Strategies for Prompt Searches for GRB Afterglows: The Discovery of GRB 001011 Optical/Near-Infrared Counterpart Using Colour-Colour Selection

NASA Technical Reports Server (NTRS)

Gorosabel, J.; Fynbo, J. U.; Hjorth, J.; Wolf, C.; Andersen, M. I.; Pedersen, H.; Christensen, L.; Jensen, B. L.; Moller, P.; Afonso, J.;

HIV-1 Tat binds to SH3 domains: cellular and viral outcome of Tat/Grb2 interaction

PubMed Central

Rom, Slava; Pacifici, Marco; Passiatore, Giovanni; Aprea, Susanna; Waligorska, Agnieszka; Valle, Luis Del; Peruzzi, Francesca

2011-01-01

The Src-homology 3 (SH3) domain is one of the most frequent protein recognition modules (PRMs), being represented in signal transduction pathways and in several pathologies such as cancer and AIDS. Grb2 (growth factor receptor-bound protein 2) is an adaptor protein that contains two SH3 domains and is involved in receptor tyrosine kinase (RTK) signal transduction pathways. The HIV-1 transactivator factor Tat is required for viral replication and it has been shown to bind directly or indirectly to several host proteins, deregulating their functions. In this study, we show interaction between the cellular factor Grb2 and the HIV-1 trans-activating protein Tat. The binding is mediated by the proline-rich sequence of Tat and the SH3 domain of Grb2. As the adaptor protein Grb2 participates in a wide variety of signaling pathways, we characterized at least one of the possible downstream effects of the Tat/Grb2 interaction on the well-known IGF-1R/Raf/MAPK cascade. We show that the binding of Tat to Grb2 impairs activation of the Raf/MAPK pathway, while potentiating the PKA/Raf inhibitory pathway. The Tat/Grb2 interaction affects also viral function by inhibiting the Tat-mediated transactivation of HIV-1 LTR and viral replication in infected primary microglia. PMID:21745501

Isolation, characterization, and evaluation of multi-trait plant growth promoting rhizobacteria for their growth promoting and disease suppressing effects on ginger.

PubMed

Dinesh, Raghavan; Anandaraj, Muthuswamy; Kumar, Aundy; Bini, Yogiyar Kundil; Subila, Kizhakke Purayil; Aravind, Ravindran

2015-04-01

In this study, 100 PGPR strains isolated from different varieties of ginger (Zingiber officinale Rosc.) were first characterized for their morphological, biochemical, and nutrient mobilization traits in vitro. The PGPR were also screened in vitro for inhibition of Pythium myriotylum causing soft rot in ginger. Results revealed that only five PGPR showed >70% suppression of P. myriotylum. These 5 PGPR viz., GRB (Ginger rhizobacteria) 25--Burkholderia cepacia, GRB35--Bacillus amyloliquefaciens; GRB58--Serratia marcescens; GRB68--S. marcescens; GRB91--Pseudomonas aeruginosa were used for further growth promotion and biocontrol studies in the green house and field. The green house study revealed that GRB35 (B. amyloliquefaciens) and GRB68 (S. marcescens) registered markedly higher sprouting (96.3%) and lower disease incidence (48.1%) and greater rhizome yield (365.6 g pot(-1) and 384.4 g pot(-1), respectively), while control registered the lowest sprouting (66%), maximum soft rot incidence (100%) and lowest rhizome yield (134.4 g pot(-1)). In the field experiments also, GRB68 (S. marcescens) and GRB35 (B. amyloliquefaciens) registered the greatest sprouting (80% each), markedly lower soft rot incidence (5.2% and 7.3%, respectively) and higher yield (5.0 and 4.3 kg(3)m(-2), respectively) compared to chemicals like Streptomycin sulphate (73.0%, 18.5% and 2.3 kg(3)m(-2), respectively), Metalaxyl-Mancozeb (73.0%, 14.0% and 3.8 kg(3)m(-2), respectively) and control (73.0%, 25.1% and 2.2 kg 3m(-2), respectively). Overall, the results suggested that for growth promotion and management of soft rot disease in ginger, GRB35 B. amyloliquefaciens and GRB68 S. marcescens could be good alternatives to chemical measures. Since, the latter has been reported to be an opportunistic human pathogen, we recommend the use of B. amyloliquefaciens for integration into nutrient and disease management schedules for ginger cultivation. Copyright © 2015 Elsevier GmbH. All rights reserved.

On the light-curve of OT/GRB970508

NASA Astrophysics Data System (ADS)

Pedersen, H.; Jaunsen, A. O.; Østensen, R.; Grav, T.; Wold, M.; Lacy, M.; Kristen, H.; Broeils, A.; Castro-Tirado, A. J.; Gorosabel, J.; Rodriguez Espinosa, J. M.; Perez, A. M.; Näslund, M.; Fransson, C.; Andersen, M. I.; Wolf, C.; Fockenbrock, R.; Piro, L.; Feroci, M.; Costa, E.; Nicastro, L.; Palazzi, E.; Frontera, F.; Monaldi, L.; Heise, J.; Hjorth, J.

1998-05-01

Using the Nordic Optical Telescope, La Palma, Spain, optical studies of OT/GRB970508 were initiated 3 hours 5 minutes after the high energy event (This appears to be sooner than achieved elsewhere, for any optical transient). The OT was clearly detected in the earliest images. The last observation was done August 13-15, i.e. 95-97 days after the event. We have combined the NOT R and unfiltered data with similar photometry from elsewhere. We conclude that the observed source brightness cannot easily be modeled by theories predicting a monotonic rise to maximum. Also the post-maximum power-law decay, albeit predicted by several models, is no longer valid at the moment of our last observation. The contribution of a constant source, mR=25.5 is indicated, but this does not show up in the image profile.

GRB-081029: A Step Towards Understanding Multiple Afterglow Components

NASA Technical Reports Server (NTRS)

Holland Stephen T.

2010-01-01

We present an analysis of the unusual optical light curve of the gamma-ray burst-081029 at a redshift of z = 3.8474. We combine X-ray and optical observations from (Swift) with optical and infrared data from REM to obtain a detailed data set extending from approx 10(exp 2)s to approx 10(exp 5)s after the BAT trigger, and from approx.10 keV to 16,000 AA. The X-ray afterglow showed a shallow initial decay followed by u rapid decay after about 18,000 s. The optical afterglow, however, shows an uncharecteristic rise at about 5000 s that has no corresponding feature in the X-ray light curve. The data are not consistent with a single-component jet. It is possible that there are multiple physical components contributing to the afterglow of GRB-081029.

Rapid fading of optical afterglows as evidence for beaming in gamma-ray bursts

NASA Astrophysics Data System (ADS)

Huang, Y. F.; Dai, Z. G.; Lu, T.

2000-03-01

Based on the refined dynamical model proposed by us earlier for beamed gamma -ray burst ejecta, we carry out detailed numerical procedure to study those gamma -ray bursts with rapidly fading afterglows (i.e., ~ t-2). It is found that optical afterglows from GRB 970228, 980326, 980519, 990123, 990510 and 991208 can be satisfactorily fitted if the gamma -ray burst ejecta are highly collimated, with a universal initial half opening angle theta_0 ~ 0.1. The obvious light curve break observed in GRB 990123 is due to the relativistic-Newtonian transition of the beamed ejecta, and the rapidly fading optical afterglows come from synchrotron emissions during the mildly relativistic and non-relativistic phases. We strongly suggest that the rapid fading of afterglows currently observed in some gamma -ray bursts is evidence for beaming in these cases.

ASTROBIOLOGICAL EFFECTS OF GAMMA-RAY BURSTS IN THE MILKY WAY GALAXY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gowanlock, Michael G., E-mail: gowanloc@mit.edu

A planet having protective ozone within the collimated beam of a gamma-ray burst (GRB) may suffer ozone depletion, potentially causing a mass extinction event to existing life on a planet’s surface and oceans. We model the dangers of long GRBs to planets in the Milky Way and utilize a static statistical model of the Galaxy, which matches major observable properties, such as the inside-out star formation history (SFH), metallicity evolution, and three-dimensional stellar number density distribution. The GRB formation rate is a function of both the SFH and metallicity. However, the extent to which chemical evolution reduces the GRB ratemore » over time in the Milky Way is still an open question. Therefore, we compare the damaging effects of GRBs to biospheres in the Milky Way using two models. One model generates GRBs as a function of the inside-out SFH. The other model follows the SFH, but generates GRB progenitors as a function of metallicity, thereby favoring metal-poor host regions of the Galaxy over time. If the GRB rate only follows the SFH, the majority of the GRBs occur in the inner Galaxy. However, if GRB progenitors are constrained to low-metallicity environments, then GRBs only form in the metal-poor outskirts at recent epochs. Interestingly, over the past 1 Gyr, the surface density of stars (and their corresponding planets), which survive a GRB is still greatest in the inner galaxy in both models. The present-day danger of long GRBs to life at the solar radius ( R {sub ⊙} = 8 kpc) is low. We find that at least ∼65% of stars survive a GRB over the past 1 Gyr. Furthermore, when the GRB rate was expected to have been enhanced at higher redshifts, such as z ≳ 0.5, our results suggest that a large fraction of planets would have survived these lethal GRB events.« less

A Missing-link in the Supernova-GRB Connection: The Case of SN 2012ap

NASA Astrophysics Data System (ADS)

Chakraborti, Sayan; Soderberg, Alicia; Chomiuk, Laura; Kamble, Atish; Yadav, Naveen; Ray, Alak; Hurley, Kevin; Margutti, Raffaella; Milisavljevic, Dan; Bietenholz, Michael; Brunthaler, Andreas; Pignata, Giuliano; Pian, Elena; Mazzali, Paolo; Fransson, Claes; Bartel, Norbert; Hamuy, Mario; Levesque, Emily; MacFadyen, Andrew; Dittmann, Jason; Krauss, Miriam; Briggs, M. S.; Connaughton, V.; Yamaoka, K.; Takahashi, T.; Ohno, M.; Fukazawa, Y.; Tashiro, M.; Terada, Y.; Murakami, T.; Goldsten, J.; Barthelmy, S.; Gehrels, N.; Cummings, J.; Krimm, H.; Palmer, D.; Golenetskii, S.; Aptekar, R.; Frederiks, D.; Svinkin, D.; Cline, T.; Mitrofanov, I. G.; Golovin, D.; Litvak, M. L.; Sanin, A. B.; Boynton, W.; Fellows, C.; Harshman, K.; Enos, H.; von Kienlin, A.; Rau, A.; Zhang, X.; Savchenko, V.

2015-06-01

Gamma-ray bursts (GRBs) are characterized by ultra-relativistic outflows, while supernovae are generally characterized by non-relativistic ejecta. GRB afterglows decelerate rapidly, usually within days, because their low-mass ejecta rapidly sweep up a comparatively larger mass of circumstellar material. However, supernovae with heavy ejecta can be in nearly free expansion for centuries. Supernovae were thought to have non-relativistic outflows except for a few relativistic ones accompanied by GRBs. This clear division was blurred by SN 2009bb, the first supernova with a relativistic outflow without an observed GRB. However, the ejecta from SN 2009bb was baryon loaded and in nearly free expansion for a year, unlike GRBs. We report the first supernova discovered without a GRB but with rapidly decelerating mildly relativistic ejecta, SN 2012ap. We discovered a bright and rapidly evolving radio counterpart driven by the circumstellar interaction of the relativistic ejecta. However, we did not find any coincident GRB with an isotropic fluence of more than one-sixth of the fluence from GRB 980425. This shows for the first time that central engines in SNe Ic, even without an observed GRB, can produce both relativistic and rapidly decelerating outflows like GRBs.

Fall-Back Disks in Long and Short GRBS

NASA Technical Reports Server (NTRS)

Cannizo, John K.; Troja, E.; Gehrels, N.

2011-01-01

We present numerical time-dependent calculations for fall-back disks relevant for GRBs in which the disk of material surrounding the black hole (BH) powering the GRB jet modulates the mass flow, and hence the strength of the jet. Given the initial existence of a small mass appr oximately less than 10(exp -4) M(solar) near the progenitor with a circularization radius approximately 10(exp 10) - 10(exp 11) cm, an una voidable consequence will be the formation of an "external disk" whose outer edge continually moves to larger radii due to angular momentum transport and lack of a confining torque. For long GRBs, if the mass distribution in the initial fall-back disk traces the progenitor envelope, then a radius approximates 10(exp 11) cm gives a time scale app roximately 10(exp 4) s for the X-ray plateau. For late times t > 10(exp 7) s a steepening due to a cooling front in the disk may have obser vational support in GRB 060729. For short GRBs, one expects most of t he mass initially to lie at small radii < 10(exp 8) cm; however the presence of even a trace amount approximately 10(exp -9) M(solar) of hi gh angular material can give a brief plateau in the light curve.

The GRB All-sky Spectrometer Experiment I: Instrument Overview and Science Drivers

NASA Astrophysics Data System (ADS)

Martinot, Zachary; Voigt, Elana; Banks, Zachary; Pober, Jonathan; Morales, Miguel F.

2015-01-01

The GRB All-sky Spectrometer Experiment (GASE) is an experiment designed to detect low frequency highly dispersed radio emission in the afterglow of a GRB. The detection of such a signal could provide a probe of IGM density as well as the conditions near the source of a GRB. The instrument used is an eight-element array of dipole antennas located on the University of Washington campus. This poster will further elaborate the design of the instrument and its scientific goals.

MASTER: high amplitude OT and OT during Fermi inspection

NASA Astrophysics Data System (ADS)

Balanutsa, P.; Lipunov, V.; Rebolo, R.; Serra-Ricart, M.; Podesta, R.; Levato, H.; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Shumkov, V.; Gress, O.; Pogrosheva, T.; Kuznetsov, A.; Kornilov, V.; Chazov, V.; Vlasenko, D.; Vladimirov, V.; Gorbunov, I.; Krylov, A.; Lopez, C.; Podesta, F.; Saffe, C.; Gabovich, A.

2017-06-01

During trigger (short GRB)/ (GRB_TIME: 17/06/04 14:28:05.09 UT, GRB_RA,Dec(2000):22h 41m 46s,+40d 40' 12", GRB_ERROR: 4.10 [deg radius, statistical only] )inspection MASTER-Kislovodsk auto-detection system detected optical transient at (RA, Dec) = 23h 01m 48.65s +41d 19m 04.2s on 2017-06-04.97120 UT. The OT unfiltered magnitude is 19.2m (limit 19.3m).

BATSE Observations of Gamma-Ray Burst Tails

NASA Technical Reports Server (NTRS)

Connaughton, Valerie; Six, N. Frank (Technical Monitor)

2001-01-01

With the discovery of low-energy radiation appearing to come from the site of gamma-ray bursts in the hours to weeks after the initial burst of gamma rays, it would appear that astronomers have seen a cosmological imprint made by the burster on its surroundings. I discuss in this paper the phenomenon of post-burst emission in BATSE (Burst and Transient Source Experiment) gamma-ray bursts at energies traditionally associated with prompt emission. By summing the background-subtracted signals from hundreds of bursts, I find that tails out to hundreds of seconds after the trigger may be a common feature of long events (duration greater than 2s), and perhaps of the shorter bursts at a lower and shorter-lived level. The tail component appears independent of both the duration (within the long GRB sample) and brightness of the prompt burst emission, and may be softer. Some individual bursts have visible tails at gamma-ray energies and the spectrum in at least a few cases is different from that of the prompt emission. Afterglow at lower energies was detected for one of these bursts, GRB-991216, raising the possibility of afterglow observations over large energy ranges using the next generation of GRB detectors in conjunction with sensitive space or ground-based telescopes.

Shock break-out: how a GRB revealed the beginnings of a supernova.

PubMed

Blustin, Alexander J

2007-05-15

In February 2006, Swift caught a gamma-ray burst (GRB) in the act of turning into a supernova, and made the first ever direct observations of the break-out and early expansion of a supernova shock wave. GRB 060218 began with an exceptionally long burst of non-thermal gamma-rays, lasting over 2000s, as a jet erupted through the surface of the star. While this was in progress, an optically-thick thermal component from the shock wave of the supernova explosion grew to prominence, and we were able to track the mildly relativistic expansion of this shell as the blackbody peak moved from the X-rays into the UV and optical bands. The initial radius of the shock implied that it was a blue supergiant that had exploded, but the lack of hydrogen emission lines in the supernova spectrum indicated a more compact star. The most likely scenario is that the shock ploughed into the massive stellar wind of a Wolf-Rayet progenitor, with the shock breaking-out and becoming visible to us once it reached the radius where the wind became optically-thin. I present the Swift observations of this landmark event, and discuss the new questions and answers it leaves us with.

GRB110721A: An extreme peak energy and signatures of the photosphere

DOE PAGES

Axelsson, M.; Baldini, L.; Barbiellini, G.; ...

2012-09-17

GRB110721A was observed by the Fermi Gamma-ray Space Telescope using its two instruments, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). This burst consisted of one major emission episode which lasted for ~24.5 s (in the GBM) and had a peak flux of (5.7 ± 0.2) × 10 –5 erg s –1 cm –2. The time-resolved emission spectrum is best modeled with a combination of a Band function and a blackbody spectrum. The peak energy of the Band component was initially 15 ± 2 MeV, which is the highest value ever detected in a GRB. We mademore » this measurement by combining GBM/BGO data with LAT Low Energy events to achieve continuous 10-100 MeV coverage. The peak energy later decreased as a power law in time with an index of –1.89 ± 0.10. The temperature of the blackbody component also decreased, starting from ~80 keV, and the decay showed a significant break after ~2 s. The spectrum provides strong constraints on the standard synchrotron model, indicating that alternative mechanisms may give rise to the emission at these energies.« less

Modularly Constructed Synthetic Granzyme B Molecule Enables Interrogation of Intracellular Proteases for Targeted Cytotoxicity.

PubMed

Ho, Patrick; Ede, Christopher; Chen, Yvonne Y

2017-08-18

Targeted therapies promise to increase the safety and efficacy of treatments against diseases ranging from cancer to viral infections. However, the vast majority of targeted therapeutics relies on the recognition of extracellular biomarkers, which are rarely restricted to diseased cells and are thus prone to severe and sometimes-fatal off-target toxicities. In contrast, intracellular antigens present a diverse yet underutilized repertoire of disease markers. Here, we report a protein-based therapeutic platform-termed Cytoplasmic Oncoprotein VErifier and Response Trigger (COVERT)-which enables the interrogation of intracellular proteases to trigger targeted cytotoxicity. COVERT molecules consist of the cytotoxic protein granzyme B (GrB) fused to an inhibitory N-terminal peptide, which can be removed by researcher-specified proteases to activate GrB function. We demonstrate that fusion of a small ubiquitin-like modifier 1 (SUMO1) protein to GrB yields a SUMO-GrB molecule that is specifically activated by the cancer-associated sentrin-specific protease 1 (SENP1). SUMO-GrB selectively triggers apoptotic phenotypes in HEK293T cells that overexpress SENP1, and it is highly sensitive to different SENP1 levels across cell lines. We further demonstrate the rational design of additional COVERT molecules responsive to enterokinase (EK) and tobacco etch virus protease (TEVp), highlighting the COVERT platform's modularity and adaptability to diverse protease targets. As an initial step toward engineering COVERT-T cells for adoptive T-cell therapy, we verified that primary human T cells can express, package, traffic, and deliver engineered GrB molecules in response to antigen stimulation. Our findings set the foundation for future intracellular-antigen-responsive therapeutics that can complement surface-targeted therapies.

SYNCHROTRON ORIGIN OF THE TYPICAL GRB BAND FUNCTION—A CASE STUDY OF GRB 130606B

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Bin-Bin; Briggs, Michael S.; Uhm, Z. Lucas

2016-01-10

We perform a time-resolved spectral analysis of GRB 130606B within the framework of a fast-cooling synchrotron radiation model with magnetic field strength in the emission region decaying with time, as proposed by Uhm and Zhang. The data from all time intervals can be successfully fit by the model. The same data can be equally well fit by the empirical Band function with typical parameter values. Our results, which involve only minimal physical assumptions, offer one natural solution to the origin of the observed GRB spectra and imply that, at least some, if not all, Band-like GRB spectra with typical Bandmore » parameter values can indeed be explained by synchrotron radiation.« less

Hypernovae: Observational aspects

NASA Astrophysics Data System (ADS)

Danziger, I. J.

2001-05-01

Following the discovery of a supernova SN 1998bw very probably associated with the γ-ray burst source GRB980425 the term ``hypernova'' has been re-defined to embrace SNe of high energy associated with GRB's. Here we discuss in some detail the observed and inferred properties of SN 1998bw and its relation to other previously observed SNe to which it may be related. A brief account is given of other relatively nearby SNe where a possible association with GRB's has been suggested ex post facto. There are also cases where less direct but suggestive evidence for a SN/GRB association has been adduced for well observed GRB events and their associated afterglow. These are also referred to. Our conclusion is that observationally we are still near the beginning of understanding which types of SNe give rise to GRB's and how frequently they occur. Nevertheless objects such as SN1998bw surely give rise to young supernova remnants with high velocity oxygen-enriched filaments. .

The association of GRB 060218 with a supernova and the evolution of the shock wave.

PubMed

Campana, S; Mangano, V; Blustin, A J; Brown, P; Burrows, D N; Chincarini, G; Cummings, J R; Cusumano, G; Della Valle, M; Malesani, D; Mészáros, P; Nousek, J A; Page, M; Sakamoto, T; Waxman, E; Zhang, B; Dai, Z G; Gehrels, N; Immler, S; Marshall, F E; Mason, K O; Moretti, A; O'Brien, P T; Osborne, J P; Page, K L; Romano, P; Roming, P W A; Tagliaferri, G; Cominsky, L R; Giommi, P; Godet, O; Kennea, J A; Krimm, H; Angelini, L; Barthelmy, S D; Boyd, P T; Palmer, D M; Wells, A A; White, N E

2006-08-31

Although the link between long gamma-ray bursts (GRBs) and supernovae has been established, hitherto there have been no observations of the beginning of a supernova explosion and its intimate link to a GRB. In particular, we do not know how the jet that defines a gamma-ray burst emerges from the star's surface, nor how a GRB progenitor explodes. Here we report observations of the relatively nearby GRB 060218 (ref. 5) and its connection to supernova SN 2006aj (ref. 6). In addition to the classical non-thermal emission, GRB 060218 shows a thermal component in its X-ray spectrum, which cools and shifts into the optical/ultraviolet band as time passes. We interpret these features as arising from the break-out of a shock wave driven by a mildly relativistic shell into the dense wind surrounding the progenitor. We have caught a supernova in the act of exploding, directly observing the shock break-out, which indicates that the GRB progenitor was a Wolf-Rayet star.

A Spatially Resolved Study of the GRB 020903 Host Galaxy

NASA Astrophysics Data System (ADS)

Thorp, Mallory D.; Levesque, Emily M.

2018-03-01

GRB 020903 is a long-duration gamma-ray burst with a host galaxy close enough and extended enough for spatially resolved observations, making it one of less than a dozen GRBs where such host studies are possible. GRB 020903 lies in a galaxy host complex that appears to consist of four interacting components. Here we present the results of spatially resolved spectroscopic observations of the GRB 020903 host. By taking observations at two different position angles, we were able to obtain optical spectra (3600–9000 Å) of multiple regions in the galaxy. We confirm redshifts for three regions of the host galaxy that match that of GRB 020903. We measure the metallicity of these regions, and find that the explosion site and the nearby star-forming regions both have comparable subsolar metallicities. We conclude that, in agreement with past spatially resolved studies of GRBs, the GRB explosion site is representative of the host galaxy as a whole rather than localized in a metal-poor region of the galaxy.

THE BLACK HOLE CENTRAL ENGINE FOR ULTRA-LONG GAMMA-RAY BURST 111209A AND ITS ASSOCIATED SUPERNOVA 2011KL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, He; You, Zhi-Qiang; Lei, Wei-Hua

Recently, the first association between an ultra-long gamma-ray burst (GRB) and a supernova was reported, i.e., GRB 111209A/SN 2011kl, enabling us to investigate the physics of central engines or even progenitors for ultra-long GRBs. In this paper, we inspect the broadband data of GRB 111209A/SN 2011kl. The late-time X-ray light curve exhibits a GRB 121027A-like fallback bump, suggesting a black hole (BH) central engine. We thus propose a collapsar model with fallback accretion for GRB 111209A/SN 2011kl. The required model parameters, such as the total mass and radius of the progenitor star, suggest that the progenitor of GRB 111209A ismore » more likely a Wolf–Rayet star instead of a blue supergiant, and the central engine of this ultra-long burst is a BH. The implications of our results are discussed.« less

Revealing Physical Activity of GRB Central Engine with Macronova/Kilonova Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Zhao-Qiang; Jin, Zhi-Ping; Liang, Yun-Feng

The modeling of Li-Paczyński macronova/kilonova signals gives a reasonable estimate on the neutron-rich material ejected during the neutron star mergers. Usually the accretion disk is more massive than the macronova ejecta, with which the efficiencies of converting the disk mass into prompt emission of three merger-driven GRBs can hence be directly constrained. Supposing the macronovae/kilonovae associated with GRB 050709, GRB 060614, and GRB 130603B arose from radioactive decay of the r -process material, the upper limit on energy conversion efficiencies are found to be as low as ∼10{sup −6}–10{sup −4}. Moreover, for all three events, neutrino annihilation is likely powerfulmore » enough to account for the brief gamma-ray flashes. Neutrino annihilation can also explain the “extended” emission lasting ∼100 s in GRB 050709, but does not work for the one in GRB 060614. These progresses demonstrate that the macronova can serve as a novel probe of the central engine activity.« less

Unveiling the Secrets of Metallicity and Massive Star Formation Using DLAs Along Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Cucchiara, A.; Fumagalli, M.; Rafelski, M.; Kocevski, D.; Prochaska, J. X.; Cooke, R. J.; Becker, G. D.

2015-01-01

We present the largest, publicly available, sample of Damped Lyman-alpha systems (DLAs) along Swift discovered Gamma-ray Bursts (GRB) line of sights in order to investigate the environmental properties of long GRB hosts in the z = 1.8 - 6 redshift range. Compared with the most recent quasar DLAs sample (QSO-DLA), our analysis shows that GRB-DLAs probe a more metal enriched environment at z approximately greater than 3, up to [X/H] approximately -0.5. In the z = 2 - 3 redshift range, despite the large number of lower limits, there are hints that the two populations may be more similar (only at 90% significance level) than at higher redshifts. Also, at high-z, the GRB-DLA average metallicity seems to decline at a shallower rate than the QSO-DLAs: GRB-DLA hosts may be polluted with metals at least as far as approximately 2 kpc from the GRB explosion site, probably due to previous star-formation episodes and/or supernovae explosions. This shallow metallicity trend, extended now up to z approximately 5, confirms previous results that GRB hosts are star-forming and have, on average, higher metallicity than the general QSO-DLA population. Finally, our host metallicity measurements are broadly consistent with the predictions derived from the hypothesis of two channels of GRB progenitors, one of which is mildly affected by a metallicity bias, although more data are needed to constrain the models at z approximately greater than 4.

A Comparative Study between a Failed and a Successful Eruption Initiated from the Same Polarity Inversion Line in AR 11387

NASA Astrophysics Data System (ADS)

Liu, Lijuan; Wang, Yuming; Zhou, Zhenjun; Dissauer, Karin; Temmer, Manuela; Cui, Jun

2018-05-01

In this paper, we analyzed a failed and a successful eruption that initiated from the same polarity inversion line within NOAA AR 11387 on 2011 December 25. They both started from a reconnection between sheared arcades, with distinct pre-eruption conditions and eruption details: before the failed one, the magnetic fields of the core region had a weaker non-potentiality; the external fields had a similar critical height for torus instability, and a similar local torus-stable region, but a larger magnetic flux ratio (of low corona and near-surface region) compared to the successful one. During the failed eruption, a smaller Lorentz force impulse was exerted on the outward ejecta; the ejecta had a much slower rising speed. Factors that might lead to the initiation of the failed eruption are identified: (1) a weaker non-potentiality of the core region, and a smaller Lorentz force impulse gave the ejecta a small momentum; (2) the large flux ratio, and the local torus-stable region in the corona provided strong confinements that made the erupting structure regain an equilibrium state.

Unusual Central Engine Activity in the Double Burst GRB 110709B

NASA Technical Reports Server (NTRS)

Zhang, Bin-Bin; Burrows, David N.; Zhang, Bing; Meszaros, Peter; Stratta, Giulia; D'Elia, Valerio; Frederiks, Dmitry; Golenetskii, S.; Cummings, Jay R.; Wang, Xiang-Yu;

Gamma-Ray Burst Afterglows with ALMA

NASA Astrophysics Data System (ADS)

Urata, Y.; Huang, K.; Takahashi, S.

2015-12-01

We present multi-wavelength observations including sub-millimeter follow-ups for two GRB afterglows. The rapid SMA and multi-wavelength observations for GRB120326A revealed their complex emissions as the synchrotron self-inverse Compton radiation from reverse shock. The observations including ALMA for GRB131030A also showed the significant X-ray excess from the standard forward shock synchrotron model. Based on these results, we also discuss further observations for (A) constraining of the mass of progenitor with polarization, (B) the first confirmation of GRB jet collimation, and (C) revealing the origin of optically dark GRBs.

Observation of X-ray lines from a gamma-ray burst (GRB991216): evidence of moving ejecta from the progenitor.

PubMed

Piro, L; Garmire, G; Garcia, M; Stratta, G; Costa, E; Feroci, M; Mészáros, P; Vietri, M; Bradt, H; Frail, D; Frontera, F; Halpern, J; Heise, J; Hurley, K; Kawai, N; Kippen, R M; Marshall, F; Murakami, T; Sokolov, V V; Takeshima, T; Yoshida, A

2000-11-03

We report on the discovery of two emission features observed in the x-ray spectrum of the afterglow of the gamma-ray burst (GRB) of 16 December 1999 by the Chandra X-ray Observatory. These features are identified with the Ly(alpha) line and the narrow recombination continuum by hydrogenic ions of iron at a redshift z = 1.00 +/- 0.02, providing an unambiguous measurement of the distance of a GRB. Line width and intensity imply that the progenitor of the GRB was a massive star system that ejected, before the GRB event, a quantity of iron approximately 0.01 of the mass of the sun at a velocity approximately 0.1 of the speed of light, probably by a supernova explosion.

FERMI Observations of High-Energy Gamma-Ray Emission from GRB 080825C

DOE PAGES

Abdo, A. A.; Ackermann, M.; Asano, K.; ...

2009-11-24

The Fermi Gamma-ray Space Telescope has opened a new high-energy window in the study of gamma-ray bursts (GRBs). Here in this paper, we present a thorough analysis of GRB 080825C, which triggered the Fermi Gamma-ray Burst Monitor (GBM), and was the first firm detection of a GRB by the Fermi Large Area Telescope (LAT). We discuss the LAT event selections, background estimation, significance calculations, and localization for Fermi GRBs in general and GRB 080825C in particular. We show the results of temporal and time-resolved spectral analysis of the GBM and LAT data. Finally, we also present some theoretical interpretation ofmore » GRB 080825C observations as well as some common features observed in other LAT GRBs.« less

Gamma-Ray Burst Supernovae as Standardizable Candles

NASA Astrophysics Data System (ADS)

Cano, Z.

2014-10-01

A long-duration gamma-ray burst (GRB) marks the violent end of a massive star. GRBs are rare in the universe, and their progenitor stars are thought to possess unique physical properties such as low metal content and rapid rotation, while the supernovae (SNe) that are associated with GRBs are expected to be highly aspherical. To date, it has been unclear whether GRB-SNe could be used as standardizable candles, with contrasting conclusions found by different teams. In this paper, I present evidence that GRB-SNe have the potential to be used as standardizable candles and show that a statistically significant relation exists between the brightness and width of their decomposed light curves relative to a template SN. Every single nearby spectroscopically identified GRB-SN for which the rest frame and host contributions have been accurately determined follows this relation. Additionally, it is shown that not only GRB-SNe, but perhaps all SNe whose explosions are powered by a central engine may eventually be used as a standardizable candle. Finally, I suggest that the use of GRB-SNe as standardizable candles likely arises from a combination of the viewing angle and similar explosion geometry in each event, the latter of which is influenced by the explosion mechanism of GRB-SNe.

A MISSING-LINK IN THE SUPERNOVA–GRB CONNECTION: THE CASE OF SN 2012ap

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborti, Sayan; Soderberg, Alicia; Kamble, Atish

2015-06-01

Gamma-ray bursts (GRBs) are characterized by ultra-relativistic outflows, while supernovae are generally characterized by non-relativistic ejecta. GRB afterglows decelerate rapidly, usually within days, because their low-mass ejecta rapidly sweep up a comparatively larger mass of circumstellar material. However, supernovae with heavy ejecta can be in nearly free expansion for centuries. Supernovae were thought to have non-relativistic outflows except for a few relativistic ones accompanied by GRBs. This clear division was blurred by SN 2009bb, the first supernova with a relativistic outflow without an observed GRB. However, the ejecta from SN 2009bb was baryon loaded and in nearly free expansion formore » a year, unlike GRBs. We report the first supernova discovered without a GRB but with rapidly decelerating mildly relativistic ejecta, SN 2012ap. We discovered a bright and rapidly evolving radio counterpart driven by the circumstellar interaction of the relativistic ejecta. However, we did not find any coincident GRB with an isotropic fluence of more than one-sixth of the fluence from GRB 980425. This shows for the first time that central engines in SNe Ic, even without an observed GRB, can produce both relativistic and rapidly decelerating outflows like GRBs.« less

The Third Swift Burst Alert Telescope Gamma-Ray Burst Catalog

NASA Astrophysics Data System (ADS)

Lien, Amy; Sakamoto, Takanori; Barthelmy, Scott D.; Baumgartner, Wayne H.; Cannizzo, John K.; Chen, Kevin; Collins, Nicholas R.; Cummings, Jay R.; Gehrels, Neil; Krimm, Hans A.; Markwardt, Craig. B.; Palmer, David M.; Stamatikos, Michael; Troja, Eleonora; Ukwatta, T. N.

2016-09-01

To date, the Burst Alert Telescope (BAT) onboard Swift has detected ˜1000 gamma-ray bursts (GRBs), of which ˜360 GRBs have redshift measurements, ranging from z = 0.03 to z = 9.38. We present the analyses of the BAT-detected GRBs for the past ˜11 years up through GRB 151027B. We report summaries of both the temporal and spectral analyses of the GRB characteristics using event data (I.e., data for each photon within approximately 250 s before and 950 s after the BAT trigger time), and discuss the instrumental sensitivity and selection effects of GRB detections. We also explore the GRB properties with redshift when possible. The result summaries and data products are available at http://swift.gsfc.nasa.gov/results/batgrbcat/index.html. In addition, we perform searches for GRB emissions before or after the event data using the BAT survey data. We estimate the false detection rate to be only one false detection in this sample. There are 15 ultra-long GRBs (˜2% of the BAT GRBs) in this search with confirmed emission beyond ˜1000 s of event data, and only two GRBs (GRB 100316D and GRB 101024A) with detections in the survey data prior to the starting of event data.

THE THIRD SWIFT BURST ALERT TELESCOPE GAMMA-RAY BURST CATALOG

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lien, Amy; Baumgartner, Wayne H.; Cannizzo, John K.

2016-09-20

To date, the Burst Alert Telescope (BAT) onboard Swift has detected ∼1000 gamma-ray bursts (GRBs), of which ∼360 GRBs have redshift measurements, ranging from z = 0.03 to z = 9.38. We present the analyses of the BAT-detected GRBs for the past ∼11 years up through GRB 151027B. We report summaries of both the temporal and spectral analyses of the GRB characteristics using event data (i.e., data for each photon within approximately 250 s before and 950 s after the BAT trigger time), and discuss the instrumental sensitivity and selection effects of GRB detections. We also explore the GRB propertiesmore » with redshift when possible. The result summaries and data products are available at http://swift.gsfc.nasa.gov/results/batgrbcat/index.html. In addition, we perform searches for GRB emissions before or after the event data using the BAT survey data. We estimate the false detection rate to be only one false detection in this sample. There are 15 ultra-long GRBs (∼2% of the BAT GRBs) in this search with confirmed emission beyond ∼1000 s of event data, and only two GRBs (GRB 100316D and GRB 101024A) with detections in the survey data prior to the starting of event data.« less

Direct time integration of Maxwell's equations in linear dispersive media with absorption for scattering and propagation of femtosecond electromagnetic pulses

NASA Technical Reports Server (NTRS)

Joseph, Rose M.; Hagness, Susan C.; Taflove, Allen

1991-01-01

The initial results for femtosecond pulse propagation and scattering interactions for a Lorentz medium obtained by a direct time integration of Maxwell's equations are reported. The computational approach provides reflection coefficients accurate to better than 6 parts in 10,000 over the frequency range of dc to 3 x 10 to the 16th Hz for a single 0.2-fs Gaussian pulse incident upon a Lorentz-medium half-space. New results for Sommerfeld and Brillouin precursors are shown and compared with previous analyses. The present approach is robust and permits 2D and 3D electromagnetic pulse propagation directly from the full-vector Maxwell's equations.

CGRO/BATSE Data Support the New Paradigm For GRB Prompt Emission and the New L-i(nTh)-E-peak,i(nTh,rest) Relation

NASA Technical Reports Server (NTRS)

Guiriec, S.; Gonzalez, M.M.; Sacahui, J.R.; Kouveliotou, C.; Gehrels, N.; McEnery, J.

2016-01-01

The paradigm for gamma-ray burst (GRB) prompt emission is changing. Since early in the Compton Gamma RayObservatory (CGRO) era, the empirical Band function has been considered a good description of the keV-MeV-gamma-ray prompt emission spectra despite the fact that its shape was very often inconsistent with the theoretical predictions, especially those expected in pure synchrotron emission scenarios. We have recently established a new observational model analyzing data of the NASA Fermi Gamma-ray Space Telescope. In this model, GRB prompt emission would be a combination of three main emission components: (i) a thermal-like component that we have interpreted so far as emission from the jet photosphere, (ii) a non-thermal component that we have interpreted so far as either synchrotron radiation from the propagating and accelerated charged particles within the jet or reprocessed jet photospheric emission, and (iii) an additional non-thermal (cutoff) power law (PL) extending from low to high energies in gamma-rays and most likely of inverse Compton origin. In this article we reanalyze some of the bright GRBs, namely GRBs 941017, 970111, and 990123, observed with the Burst And Transient Source Experiment (BATSE) on board CGRO with the new model. We conclude that BATSE data for these three GRBs are fully consistent with the recent results obtained with Fermi: some bright BATSE GRBs exhibit three separate components during the prompt phase with similar spectral parameters as those reported from Fermi data. In addition, the analysis of the BATSE GRBs with the new prompt emission model results in a relation between the time-resolved energy flux of the non-thermal component, F(in)(Th), and its corresponding nuFnu spectral peak energy,Epeak,inTh (i.e., FinThEpeak,inTh ), which has a similar index when fitted to a PL as the one initially derived from Fermi data. For GRBs with known redshifts (z) this results in a possible universal relation between the luminosity of the non-thermal component, LinTh, and its corresponding nuFnu spectral peak energy in the rest frame, Epeak,iNT,rest (i.e.,LinThEpeak,iNT,rest). We estimated the redshifts of GRBs 941017 and 970111 using GRB 990123 with z = 1.61as a reference. The estimated redshift for GRB 941017 is typical for long GRBs and the estimated redshift for GRB970111 is right in the range of the expected values for this burst.

Coupling between p210bcr-abl and Shc and Grb2 adaptor proteins in hematopoietic cells permits growth factor receptor-independent link to ras activation pathway.

PubMed

Tauchi, T; Boswell, H S; Leibowitz, D; Broxmeyer, H E

1994-01-01

Enforced expression of p210bcr-abl transforms interleukin 3 (IL-3)-dependent hematopoietic cell lines to growth factor-independent proliferation. It has been demonstrated that nonreceptor tyrosine kinase oncogenes may couple to the p21ras pathway to exert their transforming effect. In particular, p210bcr-abl was recently found to effect p21ras activation in hematopoietic cells. In this context, experiments were performed to evaluate a protein signaling pathway by which p210bcr-abl might regulate p21ras. It was asked whether Shc p46/p52, a protein containing a src-homology region 2 (SH2) domain, and known to function upstream from p21ras, might form specific complexes with p210bcr-abl and thus, possibly alter p21ras activity by coupling to the guanine nucleotide exchange factor (Sos/CDC25) through the Grb2 protein-Sos complex. This latter complex has been previously demonstrated to occur ubiquitously. We found that p210bcr-abl formed a specific complex with Shc and with Grb2 in three different murine cell lines transfected with a p210bcr-abl expression vector. There appeared to be a higher order complex containing Shc, Grb2, and bcr-abl proteins. In contrast to p210bcr-abl transformed cells, in which there was constitutive tight association between Grb2 and Shc, binding between Grb2 and Shc was Steel factor (SLF)-dependent in a SLF-responsive, nontransformed parental cell line. The SLF-dependent association between Grb2 and Shc in nontransformed cells involved formation of a complex of Grb2 with c-kit receptor after SLF treatment. Thus, p210bcr-abl appears to function in a hematopoietic p21ras activation pathway to allow growth factor-independent coupling between Grb2, which exists in a complex with the guanine nucleotide exchange factor (Sos), and p21ras. Shc may not be required for Grb2-c-kit interaction, because it fails to bind strongly to c-kit.

Probing the Cosmic Gamma-Ray Burst Rate with Trigger Simulations of the Swift Burst Alert Telescope

NASA Technical Reports Server (NTRS)

Lien, Amy; Sakamoto, Takanori; Gehrels, Neil; Palmer, David M.; Barthelmy, Scott D.; Graziani, Carlo; Cannizzo, John K.

2013-01-01

The gamma-ray burst (GRB) rate is essential for revealing the connection between GRBs, supernovae and stellar evolution. Additionally, the GRB rate at high redshift provides a strong probe of star formation history in the early universe. While hundreds of GRBs are observed by Swift, it remains difficult to determine the intrinsic GRB rate due to the complex trigger algorithm of Swift. Current studies of the GRB rate usually approximate the Swift trigger algorithm by a single detection threshold. However, unlike the previously own GRB instruments, Swift has over 500 trigger criteria based on photon count rate and additional image threshold for localization. To investigate possible systematic biases and explore the intrinsic GRB properties, we develop a program that is capable of simulating all the rate trigger criteria and mimicking the image threshold. Our simulations show that adopting the complex trigger algorithm of Swift increases the detection rate of dim bursts. As a result, our simulations suggest bursts need to be dimmer than previously expected to avoid over-producing the number of detections and to match with Swift observations. Moreover, our results indicate that these dim bursts are more likely to be high redshift events than low-luminosity GRBs. This would imply an even higher cosmic GRB rate at large redshifts than previous expectations based on star-formation rate measurements, unless other factors, such as the luminosity evolution, are taken into account. The GRB rate from our best result gives a total number of 4568 +825 -1429 GRBs per year that are beamed toward us in the whole universe.

Ginsenoside Rb1 inhibits autophagy through regulation of Rho/ROCK and PI3K/mTOR pathways in a pressure-overload heart failure rat model.

PubMed

Yang, Tianrui; Miao, Yunbo; Zhang, Tong; Mu, Ninghui; Ruan, Libo; Duan, Jinlan; Zhu, Ying; Zhang, Rongping

2018-06-01

This study was designed to explore the relationship between ginsenoside Rb1 (Grb1) and high-load heart failure (HF) in rats. The parameters of cardiac systolic function (left ventricular posterior wall thickness (LVPWT), left ventricular internal diastolic diameter (LVID), fraction shortening (FS) and mitral valves (MVs)) of rat hearts in each group were inspected by echocardiogram. The expressions of rat myocardial contractile proteins, autophagy-related proteins and the activation of Rho/ROCK and PI3K/mTOR pathways were detected by Western blot. LVPWT, FS, MVs and the expression of myocardial contractile proteins α-MHC, apoptosis-related proteins Bcl-2 and signalling pathway involved proteins pAkt and mTOR were significantly reduced in the HF, HF+5 mg/kg Grb1 (HF+Grb1-5) and HF+Grb1+arachidonic acid (AA) groups with LVID, β-MHC, cell apoptosis, cell autophagy and Rho/ROCK significantly increased compared with the control group, of which the tendency was contrary to the HF+20 mg/kg Grb1 (HF+Grb1-20) group compared with the HF group (P < 0.05). In the HF+Grb1+AA group, there was no significant change in the above indexes compared with the HF group. The results indicated that Grb1 can exert anti-HF function by inhibiting cardiomyocyte autophagy of rats through regulation of Rho/ROCK and PI3K/mTOR pathways. © 2018 Royal Pharmaceutical Society.

Synchrotron radiation and diffusive shock acceleration - A short review and GRB perspective

NASA Astrophysics Data System (ADS)

Karlica, Mile

2015-12-01

In this talk we present the sponge" model and its possible implications on the GRB afterglow light curves. "Sponge" model describes source of GRB afterglow radiation as fragmented GRB ejecta where bubbles move through the rarefied medium. In the first part of the talk a short introduction to synchrotron radiation and Fermi acceleration was presented. In the assumption that X-ray luminosity of GRB afterglow phase comes from the kinetic energy losses of clouds in ejecta medium radiated as synchrotron radiation we solved currently very simple equation of motion to find which combination of cloud and medium regime describes the afterglow light curve the best. We proposed for the first step to watch simple combinations of expansion regimes for both bubbles and surrounding medium. The closest case to the numerical fit of GRB 150403A with time power law index k = 1.38 is the combination of constant bubbles and Sedov like expanding medium with time power law index k = 1.25. Of course the question of possible mixture of variuos regime combinations is still open within this model.

Optical polarimetric observations of GRB prompt emissions by MASTER robots-telescopes net.

NASA Astrophysics Data System (ADS)

Gorbovskoy, Evgeny; Lipunov, Vladimir; Kornilov, Victor; Shatskij, Nikolaj; Kuvshi-Nov, Dmitry; Tyurina, Nataly; Belinski, Alexander; Krylov, Alexander; Balanutsa, Pavel; Chazov, Vadim; Kuznetsov, Artem; Zimnuhov, Dmitry; Balanutsa, Pavel; Kortunov, Petr; Sankovich, Anatoly; Tlatov, An-Drey; Parkhomenko, A.; Krushinsky, Vadim; Zalozhnyh, Ivan; Popov, A.; Kopytova, Taisia; Ivanov, Kirill; Yazev, Sergey; Yurkov, Vladimir

The main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 19 -20mag. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovas (including SNIa), search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes. Observations on telescopes capable to observ polarisation of GRB prompt emission have been begun in the summer of 2009. Since summer of 2009 an observations of several GRB have been made. In particular for GRB0910 and GRB091127 optical polarisation has been measured. So, for GRB091127 which supervision have begun all through 91 sec polarisation at level of several tens percent has been registered. (GCN 10231, GCN 10052, GCN 10203)

ON THE HOST GALAXY OF GRB 150101B AND THE ASSOCIATED ACTIVE GALACTIC NUCLEUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Chen; Fang, Taotao; Wang, Junfeng

We present a multi-wavelength analysis of the host galaxy of short-duration gamma-ray burst (GRB) 150101B. Follow-up optical and X-ray observations suggested that the host galaxy, 2MASX J12320498-1056010, likely harbors low-luminosity active galactic nuclei (AGNs). Our modeling of the spectral energy distribution has confirmed the nature of the AGN, making it the first reported GRB host that contains an AGN. We have also found the host galaxy is a massive elliptical galaxy with stellar population of ∼5.7 Gyr, one of the oldest among the short-duration GRB hosts. Our analysis suggests that the host galaxy can be classified as an X-ray bright,more » optically normal galaxy, and the central AGN is likely dominated by a radiatively inefficient accretion flow. Our work explores an interesting connection that may exist between GRB and AGN activities of the host galaxy, which can help in understanding the host environment of the GRB events and the roles of AGN feedback.« less

Conformational change of Sos-derived proline-rich peptide upon binding Grb2 N-terminal SH3 domain probed by NMR

NASA Astrophysics Data System (ADS)

Ogura, Kenji; Okamura, Hideyasu

2013-10-01

Growth factor receptor-bound protein 2 (Grb2) is a small adapter protein composed of a single SH2 domain flanked by two SH3 domains. The N-terminal SH3 (nSH3) domain of Grb2 binds a proline-rich region present in the guanine nucleotide releasing factor, son of sevenless (Sos). Using NMR relaxation dispersion and chemical shift analysis methods, we investigated the conformational change of the Sos-derived proline-rich peptide during the transition between the free and Grb2 nSH3-bound states. The chemical shift analysis revealed that the peptide does not present a fully random conformation but has a relatively rigid structure. The relaxation dispersion analysis detected conformational exchange of several residues of the peptide upon binding to Grb2 nSH3.

A Unified Model for GRB Prompt Emission from Optical to Gamma-Rays; Exploring GRBs as Standard Candles

NASA Technical Reports Server (NTRS)

Guiriec, S.; Kouveliotou, C.; Hartmann, D. H.; Granot, J.; Asano, K.; Meszaros, P.; Gill, R.; Gehrels, N.; McEnery, J.

2016-01-01

The origin of prompt emission from gamma-ray bursts (GRBs) remains to be an open question. Correlated prompt optical and gamma-ray emission observed in a handful of GRBs strongly suggests a common emission region, but failure to adequately fit the broadband GRB spectrum prompted the hypothesis of different emission mechanisms for the low- and high-energy radiations. We demonstrate that our multi-component model for GRB -ray prompt emission provides an excellent fit to GRB 110205A from optical to gamma-ray energies. Our results show that the optical and highest gamma-ray emissions have the same spatial and spectral origin, which is different from the bulk of the X- and softest gamma-ray radiation. Finally, our accurate redshift estimate for GRB 110205A demonstrates promise for using GRBs as cosmological standard candles.

GRB 130427A: A Nearby Ordinary Monster

NASA Technical Reports Server (NTRS)

Maselli, A.; Melandri, A.; Nava, L.; Mundell, C. G.; Kawai, N.; Campana, S.; Covino, S.; Cummings, J. R.; Cusumano, G.; Evans, P. A.;

GRB 130427A: a nearby ordinary monster.

PubMed

Maselli, A; Melandri, A; Nava, L; Mundell, C G; Kawai, N; Campana, S; Covino, S; Cummings, J R; Cusumano, G; Evans, P A; Ghirlanda, G; Ghisellini, G; Guidorzi, C; Kobayashi, S; Kuin, P; La Parola, V; Mangano, V; Oates, S; Sakamoto, T; Serino, M; Virgili, F; Zhang, B-B; Barthelmy, S; Beardmore, A; Bernardini, M G; Bersier, D; Burrows, D; Calderone, G; Capalbi, M; Chiang, J; D'Avanzo, P; D'Elia, V; De Pasquale, M; Fugazza, D; Gehrels, N; Gomboc, A; Harrison, R; Hanayama, H; Japelj, J; Kennea, J; Kopac, D; Kouveliotou, C; Kuroda, D; Levan, A; Malesani, D; Marshall, F; Nousek, J; O'Brien, P; Osborne, J P; Pagani, C; Page, K L; Page, M; Perri, M; Pritchard, T; Romano, P; Saito, Y; Sbarufatti, B; Salvaterra, R; Steele, I; Tanvir, N; Vianello, G; Wiegand, B; Weigand, B; Wiersema, K; Yatsu, Y; Yoshii, T; Tagliaferri, G

2014-01-03

Long-duration gamma-ray bursts (GRBs) are an extremely rare outcome of the collapse of massive stars and are typically found in the distant universe. Because of its intrinsic luminosity (L ~ 3 × 10(53) ergs per second) and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the γ-ray band. Here, we present a comprehensive multiwavelength view of GRB 130427A with Swift, the 2-meter Liverpool and Faulkes telescopes, and by other ground-based facilities, highlighting the evolution of the burst emission from the prompt to the afterglow phase. The properties of GRB 130427A are similar to those of the most luminous, high-redshift GRBs, suggesting that a common central engine is responsible for producing GRBs in both the contemporary and the early universe and over the full range of GRB isotropic energies.

Radioactive decay of the late-time light curves of GRB-SNe

NASA Astrophysics Data System (ADS)

Misra, Kuntal; Fruchte, Andrew Steven

2018-04-01

We present the late-time Hubble Space Telescope observations of two GRB associated supernovae, GRB 030329/SN 2003dh and XRF 060218/SN 2006aj. Using the multi-color data upto ˜ 320 days after the burst, we constrain the late-time decay nature of these supernovae. The decay rates of SN 2003dh are steeper than SN 2006aj. A comparison with two other GRB supernovae, GRB 980425/SN 1998bw and the supernova associated with XRF 020903, shows that the decay rates of SN 2003dh are similar to XRF 020903 and those of SN 2006aj are similar to SN 1998bw. The late-time decay rates are steeper than the 56Co?56Fe radioactive decay rate (0.0098 mag day-1) indicating that there is some leakage of gamma-rays.

Adaptor protein GRB2 promotes Src tyrosine kinase activation and podosomal organization by protein-tyrosine phosphatase ϵ in osteoclasts.

PubMed

Levy-Apter, Einat; Finkelshtein, Eynat; Vemulapalli, Vidyasiri; Li, Shawn S-C; Bedford, Mark T; Elson, Ari

2014-12-26

The non-receptor isoform of protein-tyrosine phosphatase ϵ (cyt-PTPe) supports adhesion of bone-resorbing osteoclasts by activating Src downstream of integrins. Loss of cyt-PTPe reduces Src activity in osteoclasts, reduces resorption of mineralized matrix both in vivo and in cell culture, and induces mild osteopetrosis in young female PTPe KO mice. Activation of Src by cyt-PTPe is dependent upon this phosphatase undergoing phosphorylation at its C-terminal Tyr-638 by partially active Src. To understand how cyt-PTPe activates Src, we screened 73 Src homology 2 (SH2) domains for binding to Tyr(P)-638 of cyt-PTPe. The SH2 domain of GRB2 bound Tyr(P)-638 of cyt-PTPe most prominently, whereas the Src SH2 domain did not bind at all, suggesting that GRB2 may link PTPe with downstream molecules. Further studies indicated that GRB2 is required for activation of Src by cyt-PTPe in osteoclast-like cells (OCLs) in culture. Overexpression of GRB2 in OCLs increased activating phosphorylation of Src at Tyr-416 and of cyt-PTPe at Tyr-638; opposite results were obtained when GRB2 expression was reduced by shRNA or by gene inactivation. Phosphorylation of cyt-PTPe at Tyr-683 and its association with GRB2 are integrin-driven processes in OCLs, and cyt-PTPe undergoes autodephosphorylation at Tyr-683, thus limiting Src activation by integrins. Reduced GRB2 expression also reduced the ability of bone marrow precursors to differentiate into OCLs and reduced the fraction of OCLs in which podosomal adhesion structures assume organization typical of active, resorbing cells. We conclude that GRB2 physically links cyt-PTPe with Src and enables cyt-PTPe to activate Src downstream of activated integrins in OCLs. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

miR-411-5p inhibits proliferation and metastasis of breast cancer cell via targeting GRB2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yunda; State Key Laboratory of Cellular Stress Biology, Innovation Center for Cell Signaling Network, School of Life Sciences, Xiamen University, Xiamen 361102; Xu, Guoxing

miR-411-5p (previously called miR-411) is severely involved in human diseases, however, the relationship between miR-411-5p and breast cancer has not been investigated thoroughly. Here, we found that the expression of miR-411-5p was downregulated in breast cancer tissues compared with their matched adjacent non-neoplastic tissues. In addition, the expression of miR-411-5p was also lower in breast cancer cell lines in contrast with MCF-10A. Moreover, we investigated the target and mechanism of miR-411-5p in breast cancer using mimic and inhibitor, and demonstrated the involvement of GRB2 and Ras activation. Ectopic expression of miR-411-5p suppressed the breast cancer cell proliferation, migration and invasionmore » while low expression of miR-411-5p exhibited the opposite effect. Furthermore, GRB2 was demonstrated to be significantly overexpressed in breast cancer tissues compared with normal tissues, and low expression of GRB2 had a longer overall survival compared with high expression of GRB2 in breast cancer. In general, our study shed light on the miR-411-5p related mechanism in the progression of breast cancer and, miR-411-5p/GRB2/Ras axis is potential to be molecular target for breast cancer therapy. - Highlights: • miR-411-5p is downregulated in breast cancer tissues and cell lines. • miR-411-5p inhibits breast cancer cells growth, migration and invasion in vitro. • GRB2 is a direct target of miR-411-5p in breast cancer. • GRB2 is overexpressed in breast cancer and associates with disease outcome. • miR-411-5p suppresses breast cancer progression though GRB2-SOS-Ras pathway.« less

Ginsenoside Rb1 ameliorates liver fat accumulation by upregulating perilipin expression in adipose tissue of db/db obese mice

PubMed Central

Yu, Xizhong; Ye, Lifang; Zhang, Hao; Zhao, Juan; Wang, Guoqiang; Guo, Chao; Shang, Wenbin

2014-01-01

Background Ginsenoside Rb1 (G-Rb1), the major active constituent of ginseng, improves insulin sensitivity and exerts antidiabetic effects. We tested whether the insulin-sensitizing and antidiabetic effects of G-Rb1 results from a reduction in ectopic fat accumulation, mediated by inhibition of lipolysis in adipocytes. Methods Obese and diabetic db/db mice were treated with daily doses of 20 mg/kg G-Rb1 for 14 days. Hepatic fat accumulation was evaluated by measuring liver weight and triglyceride content. Levels of blood glucose and serum insulin were used to evaluate insulin sensitivity in db/db mice. Lipolysis in adipocytes was evaluated by measuring plasma-free fatty acids and glycerol release from 3T3-L1 adipocytes treated with G-Rb1. The expression of relevant genes was analyzed by western blotting, quantitative real-time polymerase chain reaction, and enzyme-linked immunosorbent assay kit. Results G-Rb1 increased insulin sensitivity and alleviated hepatic fat accumulation in obese diabetic db/db mice, and these effects were accompanied by reduced liver weight and hepatic triglyceride content. Furthermore, G-Rb1 lowered the levels of free fatty acids in obese mice, which may contribute to a decline in hepatic lipid accumulation. Corresponding to these results, G-Rb1 significantly suppressed lipolysis in 3T3-L1 adipocytes and upregulated the perilipin expression in both 3T3-L1 adipocytes and mouse epididymal fat pads. Moreover, G-Rb1 increased the level of adiponectin and reduced that of tumor necrosis factor-α in obese mice, and these effects were confirmed in 3T3-L1 adipocytes. Conclusion G-Rb1 may improve insulin sensitivity in obese and diabetic db/db mice by reducing hepatic fat accumulation and suppressing adipocyte lipolysis; these effects may be mediated via the upregulation of perilipin expression in adipocytes. PMID:26199550

The 'Supercritical Pile' GRB Model: Afterglows and GRB, XRR, XRF Unification

NASA Technical Reports Server (NTRS)

Kazanas, D.

2007-01-01

We present the general notions and observational consequences of the "Supercritical Pile" GRB model; the fundamental feature of this model is a detailed process for the conversion of the energy stored in relativistic protons in the GRB Relativistic Blast Waves (RBW) into relativistic electrons and then into radiation. The conversion is effected through the $p \\, \\gamma \\rightarrow p \\, e circumflex + e circumflex -$ reaction, whose kinematic threshold is imprinted on the GRB spectra to provide a peak of their emitted luminosity at energy \\Ep $\\sim 1$ MeV in the lab frame. We extend this model to include, in addition to the (quasi--)thermal relativistic post-shock protons an accelerated component of power law form. This component guarantees the production of $e circumflex +e circumflex- - $pairs even after the RBW has slowed down to the point that its (quasi-) thermal protons cannot fulfill the threshold of the above reaction. We suggest that this last condition marks the transition from the prompt to the afterglow GRB phase. We also discuss conditions under which this transition is accompanied by a significant drop in the flux and could thus account for several puzzling, recent observations. Finally, we indicate that the same mechanism applied to the late stages of the GRB evolution leads to a decrease in \\Ep $\\propto \\Gamma circumflex 2(t)\\propto t circumflex {-3/4}$, a feature amenable to future observational tests.

Mass and metallicity scaling relations of high-redshift star-forming galaxies selected by GRBs

NASA Astrophysics Data System (ADS)

Arabsalmani, M.; Møller, P.; Perley, D. A.; Freudling, W.; Fynbo, J. P. U.; Le Floc'h, E.; Zwaan, M. A.; Schulze, S.; Tanvir, N. R.; Christensen, L.; Levan, A. J.; Jakobsson, P.; Malesani, D.; Cano, Z.; Covino, S.; D'Elia, V.; Goldoni, P.; Gomboc, A.; Heintz, K. E.; Sparre, M.; de Ugarte Postigo, A.; Vergani, S. D.

2018-01-01

We present a comprehensive study of the relations between gas kinematics, metallicity and stellar mass in a sample of 82 gamma-ray burst (GRB)-selected galaxies using absorption and emission methods. We find the velocity widths of both emission and absorption profiles to be a proxy of stellar mass. We also investigate the velocity-metallicity correlation and its evolution with redshift. Using 33 GRB hosts with measured stellar mass and metallicity, we study the mass-metallicity relation for GRB host galaxies in a stellar mass range of 108.2-1011.1 M⊙ and a redshift range of z ∼ 0.3-3.4. The GRB-selected galaxies appear to track the mass-metallicity relation of star-forming galaxies but with an offset of 0.15 towards lower metallicities. This offset is comparable with the average error bar on the metallicity measurements of the GRB sample and also the scatter on the mass-metallicity relation of the general population. It is hard to decide whether this relatively small offset is due to systematic effects or the intrinsic nature of GRB hosts. We also investigate the possibility of using absorption-line metallicity measurements of GRB hosts to study the mass-metallicity relation at high redshifts. Our analysis shows that the metallicity measurements from absorption methods can significantly differ from emission metallicities and assuming identical measurements from the two methods may result in erroneous conclusions.

GrpL, a Grb2-related Adaptor Protein, Interacts with SLP-76 to Regulate Nuclear Factor of Activated T Cell Activation

PubMed Central

Law, Che-Leung; Ewings, Maria K.; Chaudhary, Preet M.; Solow, Sasha A.; Yun, Theodore J.; Marshall, Aaron J.; Hood, Leroy; Clark, Edward A.

1999-01-01

Propagation of signals from the T cell antigen receptor (TCR) involves a number of adaptor molecules. SH2 domain–containing protein 76 (SLP-76) interacts with the guanine nucleotide exchange factor Vav to activate the nuclear factor of activated cells (NF-AT), and its expression is required for normal T cell development. We report the cloning and characterization of a novel Grb2-like adaptor molecule designated as Grb2-related protein of the lymphoid system (GrpL). Expression of GrpL is restricted to hematopoietic tissues, and it is distinguished from Grb2 by having a proline-rich region. GrpL can be coimmunoprecipitated with SLP-76 but not with Sos1 or Sos2 from Jurkat cell lysates. In contrast, Grb2 can be coimmunoprecipitated with Sos1 and Sos2 but not with SLP-76. Moreover, tyrosine-phosphorylated LAT/pp36/38 in detergent lysates prepared from anti-CD3 stimulated T cells associated with Grb2 but not GrpL. These data reveal the presence of distinct complexes involving GrpL and Grb2 in T cells. A functional role of the GrpL–SLP-76 complex is suggested by the ability of GrpL to act alone or in concert with SLP-76 to augment NF-AT activation in Jurkat T cells. PMID:10209041

An optical supernova associated with the X-ray flash XRF 060218.

PubMed

Pian, E; Mazzali, P A; Masetti, N; Ferrero, P; Klose, S; Palazzi, E; Ramirez-Ruiz, E; Woosley, S E; Kouveliotou, C; Deng, J; Filippenko, A V; Foley, R J; Fynbo, J P U; Kann, D A; Li, W; Hjorth, J; Nomoto, K; Patat, F; Sauer, D N; Sollerman, J; Vreeswijk, P M; Guenther, E W; Levan, A; O'Brien, P; Tanvir, N R; Wijers, R A M J; Dumas, C; Hainaut, O; Wong, D S; Baade, D; Wang, L; Amati, L; Cappellaro, E; Castro-Tirado, A J; Ellison, S; Frontera, F; Fruchter, A S; Greiner, J; Kawabata, K; Ledoux, C; Maeda, K; Møller, P; Nicastro, L; Rol, E; Starling, R

2006-08-31

Long-duration gamma-ray bursts (GRBs) are associated with type Ic supernovae that are more luminous than average and that eject material at very high velocities. Less-luminous supernovae were not hitherto known to be associated with GRBs, and therefore GRB-supernovae were thought to be rare events. Whether X-ray flashes--analogues of GRBs, but with lower luminosities and fewer gamma-rays--can also be associated with supernovae, and whether they are intrinsically 'weak' events or typical GRBs viewed off the axis of the burst, is unclear. Here we report the optical discovery and follow-up observations of the type Ic supernova SN 2006aj associated with X-ray flash XRF 060218. Supernova 2006aj is intrinsically less luminous than the GRB-supernovae, but more luminous than many supernovae not accompanied by a GRB. The ejecta velocities derived from our spectra are intermediate between these two groups, which is consistent with the weakness of both the GRB output and the supernova radio flux. Our data, combined with radio and X-ray observations, suggest that XRF 060218 is an intrinsically weak and soft event, rather than a classical GRB observed off-axis. This extends the GRB-supernova connection to X-ray flashes and fainter supernovae, implying a common origin. Events such as XRF 060218 are probably more numerous than GRB-supernovae.

Maltose-Binding Protein Enhances Secretion of Recombinant Human Granzyme B Accompanied by In Vivo Processing of a Precursor MBP Fusion Protein

PubMed Central

Dälken, Benjamin; Jabulowsky, Robert A.; Oberoi, Pranav; Benhar, Itai; Wels, Winfried S.

2010-01-01

Background The apoptosis-inducing serine protease granzyme B (GrB) is an important factor contributing to lysis of target cells by cytotoxic lymphocytes. Expression of enzymatically active GrB in recombinant form is a prerequisite for functional analysis and application of GrB for therapeutic purposes. Methods and Findings We investigated the influence of bacterial maltose-binding protein (MBP) fused to GrB via a synthetic furin recognition motif on the expression of the MBP fusion protein also containing an N-terminal α-factor signal peptide in the yeast Pichia pastoris. MBP markedly enhanced the amount of GrB secreted into culture supernatant, which was not the case when GrB was fused to GST. MBP-GrB fusion protein was cleaved during secretion by an endogenous furin-like proteolytic activity in vivo, liberating enzymatically active GrB without the need of subsequent in vitro processing. Similar results were obtained upon expression of a recombinant fragment of the ErbB2/HER2 receptor protein or GST as MBP fusions. Conclusions Our results demonstrate that combination of MBP as a solubility enhancer with specific in vivo cleavage augments secretion of processed and functionally active proteins from yeast. This strategy may be generally applicable to improve folding and increase yields of recombinant proteins. PMID:21203542

α-Lipoic acid inhibits human lung cancer cell proliferation through Grb2-mediated EGFR downregulation.

PubMed

Yang, Lan; Wen, Ya; Lv, Guoqing; Lin, Yuntao; Tang, Junlong; Lu, Jingxiao; Zhang, Manqiao; Liu, Wen; Sun, Xiaojuan

2017-12-09

Alpha lipoic acid (α -LA) is a naturally occurring antioxidant and metabolic enzyme co-factor. Recently, α -LA has been reported to inhibit the growth of various cancer cells, but the precise signaling pathways that mediate the effects of α -LA on non-small cell lung cancer (NSCLC) development remain unclear. The CCK-8 assay was used to assess cell proliferation in NSCLC cell lines after α -LA treatment. The expression of growth factor receptor-bound protein 2 (Grb2), cyclin-dependent kinase (CDK)-2, CDK4, CDK6, Cyclin D3, Cyclin E1, Ras, c-Raf, epidermal growth factor receptor (EGFR), ERK1/2 and activated EGFR and ERK1/2 was evaluated by western blotting. Grb2 levels were restored in α-LA-treated cells by transfection of a plasmid carrying Grb2 and were reduced in NSCLC cells via specific siRNA-mediated knockdown. α -LA dramatically decreased NSCLC cell proliferation by downregulating Grb2; in contrast, Grb2 overexpression significantly prevented α-LA-induced decrease in cell growth in vitro. Western blot analysis indicated that α-LA decreased the levels of phospho-EGFR, CDK2/4/6, Cyclins D3 and E1, which are associated with the inhibition of G1/S-phase transition. Additional experiments indicated that Grb2 inhibition partially abolished EGF-induced phospho-EGFR and phospho-ERK1/2 activity. In addition, α-LA exerted greater inhibitory effects than gefitinib on NSCLC cells by preventing EGF-induced EGFR activation. For the first time, these findings provide the first evidence that α-LA inhibits cell proliferation through Grb2 by suppressing EGFR phosphorylation and that MAPK/ERK is involved in this pathway. Copyright © 2017. Published by Elsevier Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Getachew, Yonas, E-mail: yonas.getachew@utsouthwestern.edu; Cusimano, Frank A.; James, Laura P.

The role of the immune system, specifically NK, NKT and CD3 cells, in acetaminophen (APAP) induced liver injury remains inconsistently defined. In the present study, wild type (C57BL/6J) mice and granzyme B deficient (GrB −/−) mice were treated with acetaminophen to assess the role of the immune system in acute liver injury. Doses of acetaminophen that induced sub lethal liver injury in wild type mice unexpectedly produced fatal hepatotoxicity in granzyme B deficient (GrB −/−) mice. Analysis revealed that GrB −/− mice had an increased population of intrahepatic CD3 (+), CD4 (−), and CD8 (−) lymphocytes expressing the CD69 activationmore » marker and Fas ligand. Depletion of these cells in the GrB −/− and wild type mice made them less susceptible to APAP injury, while depletion of NK1.1 (+) cells or both CD4 (+) and CD8 (+) T cells failed to provide the same hepatoprotection. Transfer of the GrB −/− IHLs further exacerbated liver injury and increased mortality in wild type mice but not in LRP/LPR mice, lacking fas expression. Conclusions: Acetaminophen toxicity is enhanced by the presence of activated, FasL expressing intrahepatic CD3 (+), CD4 (−), CD8 (−), NK1.1 (−) T cells. Depletion of these cells from GrB −/− mice and wild type mice greatly reduces mortality and improves the course of liver injury recovery. - Highlights: • Intrahepatic lymphocytes (IHLs) from GrB −/− mice harbor activated DNT cells. • IHLs from GrB −/− mice exhibit enhanced Fas ligand expression. • Acetaminophen toxicity is enhanced by activated, FasL expressing DNT cells.« less

Relationship between quantitative GRB7 RNA expression and recurrence after adjuvant anthracycline chemotherapy in triple-negative breast cancer.

PubMed

Sparano, Joseph A; Goldstein, Lori J; Childs, Barrett H; Shak, Steven; Brassard, Diana; Badve, Sunil; Baehner, Frederick L; Bugarini, Roberto; Rowley, Steve; Perez, Edith A; Shulman, Lawrence N; Martino, Silvana; Davidson, Nancy E; Kenny, Paraic A; Sledge, George W; Gray, Robert

2011-11-15

To conduct an exploratory analysis of the relationship between gene expression and recurrence in patients with operable triple-negative breast cancer (TNBC) treated with adjuvant doxorubicin-containing chemotherapy. RNA was extracted from archived tumor samples derived from 246 patients with stage I-III TNBC treated with adjuvant doxorubicin-containing chemotherapy, and was analyzed by quantitative reverse transcriptase PCR for a panel of 374 genes. The relationship between gene expression and recurrence was evaluated using weighted Cox proportional hazards model score tests. Growth factor receptor bound protein 7 (GRB7) was the only gene for which higher expression was significantly associated with increased recurrence in TNBC (Korn's adjusted P value = 0.04). In a Cox proportional hazards model adjusted for clinicopathologic features, higher GRB7 expression was associated with an increased recurrence risk (HR = 2.31; P = 0.04 using the median as the split). The 5-year recurrence rates were 10.5% [95% confidence intervals (CI), 7.8-14.1] in the low and 20.4% (95% CI, 16.5-25.0) in the high GRB7 groups. External validation in other datasets indicated that GRB7 expression was not prognostic in two adjuvant trials including variable systemic therapy, but in two other trials showed that high GBR7 expression was associated with resistance to neoadjuvant doxorubicin and taxane therapy. GRB7 was associated with an increased risk of recurrence in TNBC, suggesting that GRB7 or GRB7-dependent pathways may serve as potential biomarkers for therapeutic targets. Therapeutic targeting of one or more factors identified which function as interaction nodes or effectors should also be considered.

Relationship Between Quantitative GRB7 RNA Expression and Recurrence after Adjuvant Anthracycline Chemotherapy in Triple Negative Breast Cancer

PubMed Central

Sparano, Joseph A.; Goldstein, Lori J.; Childs, Barrett H.; Shak, Steven; Brassard, Diana; Badve, Sunil; Baehner, Frederick L.; Bugarini, Roberto; Rowley, Steve; Perez, Edith; Shulman, Lawrence N.; Martino, Silvana; Davidson, Nancy E.; Kenny, Paraic A.; Sledge, George W.; Gray, Robert

2012-01-01

Purpose To perform an exploratory analysis of the relationship between gene expression and recurrence in patients with operable triple negative breast cancer (TNBC) treated with adjuvant doxorubicin-containing chemotherapy. Experimental design RNA was extracted from archived tumor samples derived from 246 patients with stage I-III TNBC treated with adjuvant doxorubicin-containing chemotherapy, and was analyzed by quantitative RT-PCR for a panel of 374 genes. The relationship between gene expression and recurrence was evaluated using weighted Cox proportional hazards model score tests. Results GRB7 was the only gene for which higher expression was significantly associated with increased recurrence in TNBC (Korn’s adjusted p value=0.04). In a Cox proportional hazards model adjusted for clinicopathologic features, higher GRB7 expression was associated with an increased recurrence risk (HR 2.31, p=0.04 using the median as the split). The 5-year recurrence rates were 10.5% (95% confidence intervals [CI] 7.8%, 14.1%) in the low and 20.4% (95% CI 16.5%, 25.0%) in the high GRB7 groups. External validation in other datasets indicated that GRB7 expression was not prognostic in two adjuvant trials including variable systemic therapy, but in two other trials showed that high GBR7 expression was associated with resistance to neoadjuvant doxorubicin and taxane therapy. Conclusions GRB7 was associated with an increased risk of recurrence in TNBC, suggesting that GRB7 or GRB7-dependent pathways may serve as potential biomarkers for therapeutic targets. Therapeutic targeting of one or more factors identified which function as interaction nodes or effectors should also be considered. PMID:21933890

Probing the cosmic gamma-ray burst rate with trigger simulations of the swift burst alert telescope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lien, Amy; Cannizzo, John K.; Sakamoto, Takanori

The gamma-ray burst (GRB) rate is essential for revealing the connection between GRBs, supernovae, and stellar evolution. Additionally, the GRB rate at high redshift provides a strong probe of star formation history in the early universe. While hundreds of GRBs are observed by Swift, it remains difficult to determine the intrinsic GRB rate due to the complex trigger algorithm of Swift. Current studies of the GRB rate usually approximate the Swift trigger algorithm by a single detection threshold. However, unlike the previously flown GRB instruments, Swift has over 500 trigger criteria based on photon count rate and an additional imagemore » threshold for localization. To investigate possible systematic biases and explore the intrinsic GRB properties, we develop a program that is capable of simulating all the rate trigger criteria and mimicking the image threshold. Our simulations show that adopting the complex trigger algorithm of Swift increases the detection rate of dim bursts. As a result, our simulations suggest that bursts need to be dimmer than previously expected to avoid overproducing the number of detections and to match with Swift observations. Moreover, our results indicate that these dim bursts are more likely to be high redshift events than low-luminosity GRBs. This would imply an even higher cosmic GRB rate at large redshifts than previous expectations based on star formation rate measurements, unless other factors, such as the luminosity evolution, are taken into account. The GRB rate from our best result gives a total number of 4568{sub −1429}{sup +825} GRBs per year that are beamed toward us in the whole universe.« less

A Central Role for GRB10 in Regulation of Islet Function in Man

PubMed Central

Prasad B, Rashmi; Salehi, S. Albert; Almgren, Peter; Osmark, Peter; Bouatia-Naji, Nabila; Wierup, Nils; Fall, Tove; Stančáková, Alena; Barker, Adam; Lagou, Vasiliki; Osmond, Clive; Xie, Weijia; Lahti, Jari; Jackson, Anne U.; Cheng, Yu-Ching; Liu, Jie; O'Connell, Jeffrey R.; Blomstedt, Paul A.; Fadista, Joao; Alkayyali, Sami; Dayeh, Tasnim; Ahlqvist, Emma; Taneera, Jalal; Lecoeur, Cecile; Kumar, Ashish; Hansson, Ola; Hansson, Karin; Voight, Benjamin F.; Kang, Hyun Min; Levy-Marchal, Claire; Vatin, Vincent; Palotie, Aarno; Syvänen, Ann-Christine; Mari, Andrea; Weedon, Michael N.; Loos, Ruth J. F.; Ong, Ken K.; Nilsson, Peter; Isomaa, Bo; Tuomi, Tiinamaija; Wareham, Nicholas J.; Stumvoll, Michael; Widen, Elisabeth; Lakka, Timo A.; Langenberg, Claudia; Tönjes, Anke; Rauramaa, Rainer; Kuusisto, Johanna; Frayling, Timothy M.; Froguel, Philippe; Walker, Mark; Eriksson, Johan G.; Ling, Charlotte; Kovacs, Peter; Ingelsson, Erik; McCarthy, Mark I.; Shuldiner, Alan R.; Silver, Kristi D.; Laakso, Markku; Groop, Leif; Lyssenko, Valeriya

2014-01-01

Variants in the growth factor receptor-bound protein 10 (GRB10) gene were in a GWAS meta-analysis associated with reduced glucose-stimulated insulin secretion and increased risk of type 2 diabetes (T2D) if inherited from the father, but inexplicably reduced fasting glucose when inherited from the mother. GRB10 is a negative regulator of insulin signaling and imprinted in a parent-of-origin fashion in different tissues. GRB10 knock-down in human pancreatic islets showed reduced insulin and glucagon secretion, which together with changes in insulin sensitivity may explain the paradoxical reduction of glucose despite a decrease in insulin secretion. Together, these findings suggest that tissue-specific methylation and possibly imprinting of GRB10 can influence glucose metabolism and contribute to T2D pathogenesis. The data also emphasize the need in genetic studies to consider whether risk alleles are inherited from the mother or the father. PMID:24699409

Constraints on an Optical Afterglow and on Supernova Light Following the Short Burst GRB 050813

NASA Technical Reports Server (NTRS)

Ferrero, P.; Sanchez, S. F.; Kann, D. A.; Klose, S.; Greiner, J.; Gorosabel, J.; Hartmann, D. H.; Henden, A. A.; Moller, P.; Palazzi, E.;

The Swift GRB Host Galaxy Legacy Survey

NASA Astrophysics Data System (ADS)

Perley, Daniel A.

2015-01-01

I introduce the Swift Host Galaxy Legacy Survey (SHOALS), a comprehensive multiwavelength program to characterize the demographics of the GRB host population across its entire redshift range. Using unbiased selection criteria we have designated a subset of 130 Swift gamma-ray bursts which are now being targeted with intensive observational follow-up. Deep Spitzer imaging of every field has already been obtained and analyzed, with major programs ongoing at Keck, GTC, and Gemini to obtain complementary optical/NIR photometry to enable full SED modeling and derivation of fundamental physical parameters such as mass, extinction, and star-formation rate. Using these data I will present an unbiased measurement of the GRB host-galaxy luminosity and mass functions and their evolution with redshift between z=0 and z=5, compare GRB hosts to other star-forming galaxy populations, and discuss implications for the nature of the GRB progenitor and the ability of GRBs to probe cosmic star-formation.

The Very Red Afterglow of GRB 000418: Further Evidence for Dust Extinction in a Gamma-Ray Burst Host Galaxy

NASA Astrophysics Data System (ADS)

Klose, S.; Stecklum, B.; Masetti, N.; Pian, E.; Palazzi, E.; Henden, A. A.; Hartmann, D. H.; Fischer, O.; Gorosabel, J.; Sánchez-Fernández, C.; Butler, D.; Ott, Th.; Hippler, S.; Kasper, M.; Weiss, R.; Castro-Tirado, A.; Greiner, J.; Bartolini, C.; Guarnieri, A.; Piccioni, A.; Benetti, S.; Ghinassi, F.; Magazzú, A.; Hurley, K.; Cline, T.; Trombka, J.; McClanahan, T.; Starr, R.; Goldsten, J.; Gold, R.; Mazets, E.; Golenetskii, S.; Noeske, K.; Papaderos, P.; Vreeswijk, P. M.; Tanvir, N.; Oscoz, A.; Muñoz, J. A.; Castro Cerón, J. M.

2000-12-01

We report near-infrared and optical follow-up observations of the afterglow of the GRB 000418 starting 2.5 days after the occurrence of the burst and extending over nearly 7 weeks. GRB 000418 represents the second case for which the afterglow was initially identified by observations in the near-infrared. During the first 10 days its R-band afterglow was well characterized by a single power-law decay with a slope of 0.86. However, at later times the temporal evolution of the afterglow flattens with respect to a simple power-law decay. Attributing this to an underlying host galaxy, we find its magnitude to be R=23.9 and an intrinsic afterglow decay slope of 1.22. The afterglow was very red with R-K~4 mag. The observations can be explained by an adiabatic, spherical fireball solution and a heavy reddening due to dust extinction in the host galaxy. This supports the picture that (long) bursts are associated with events in star-forming regions. Based on observations collected at the Bologna Astronomical Observatory in Loiano, Italy; at the TNG, Canary Islands, Spain; at the German-Spanish Astronomical Centre, Calar Alto, operated by the Max-Planck-Institut for Astronomy, Heidelberg, jointly with the Spanish National Commission for Astronomy; at the US Naval Observatory; and at the UK Infrared Telescope.

The X-Ray Light Curve in GRB 170714A: Evidence for a Quark Star?

NASA Astrophysics Data System (ADS)

Hou, Shu-Jin; Liu, Tong; Xu, Ren-Xin; Mu, Hui-Jun; Song, Cui-Ying; Lin, Da-Bin; Gu, Wei-Min

2018-02-01

Two plateaus and a following bump in the X-ray light curve of GRB 170714A have been detected by the Swift/X-ray Telescope, which could be very significant for the central engine of gamma-ray bursts (GRBs), implying that the origin of this burst might be different from those of other ultra-long GRBs. We propose that merging two neutron stars into a hyper-massive quark star (QS) and then collapsing into a black hole (BH), with a delay time around 104 s, could be responsible for these X-ray components. The hyper-massive QS is initially in a fluid state, being turbulent and differentially rotating, but would solidify and release its latent heat, injecting it into the GRB fireball (lasting about 103 s during the liquid–solid phase transition). A magnetic field as high as ∼1015 G can be created by dynamo action of the newborn liquid QS, and a magnetar-like central engine (after solidification) supplies significant energy for the second plateau. More energy could be released during a fall-back accretion after the post-merger QS collapses to a BH, and the X-ray bump forms. This post-merger QS model could be tested by future observations, with either advanced gravitational wave detectors (e.g., advanced LIGO and VIRGO) or X-ray/optical telescopes.

The MUSE view of the host galaxy of GRB 100316D

NASA Astrophysics Data System (ADS)

Izzo, L.; Thöne, C. C.; Schulze, S.; Mehner, A.; Flores, H.; Cano, Z.; de Ugarte Postigo, A.; Kann, D. A.; Amorín, R.; Anderson, J. P.; Bauer, F. E.; Bensch, K.; Christensen, L.; Covino, S.; Della Valle, M.; Fynbo, J. P. U.; Jakobsson, P.; Klose, S.; Kuncarayakti, H.; Leloudas, G.; Milvang-Jensen, B.; Møller, P.; Puech, M.; Rossi, A.; Sánchez-Ramírez, R.; Vergani, S. D.

2017-12-01

The low distance, z = 0.0591, of GRB 100316D and its association with SN 2010bh represent two important motivations for studying this host galaxy and the GRB's immediate environment with the integral field spectrographs like Very Large Telescope/Multi-Unit Spectroscopic Explorer. Its large field of view allows us to create 2D maps of gas metallicity, ionization level and the star formation rate (SFR) distribution maps, as well as to investigate the presence of possible host companions. The host is a late-type dwarf irregular galaxy with multiple star-forming regions and an extended central region with signatures of on-going shock interactions. The gamma-ray burst (GRB) site is characterized by the lowest metallicity, the highest SFR and the youngest (∼20-30 Myr) stellar population in the galaxy, which suggest a GRB progenitor stellar population with masses up to 20-40 M⊙. We note that the GRB site has an offset of ∼660 pc from the most luminous SF region in the host. The observed SF activity in this galaxy may have been triggered by a relatively recent gravitational encounter between the host and a small undetected (LH α ≤ 1036 erg s-1) companion.

Afterglows and Kilonovae Associated with Nearby Low-luminosity Short-duration Gamma-Ray Bursts: Application to GW170817/GRB 170817A

NASA Astrophysics Data System (ADS)

Xiao, Di; Liu, Liang-Duan; Dai, Zi-Gao; Wu, Xue-Feng

2017-12-01

Very recently, the gravitational-wave (GW) event GW170817 was discovered to be associated with the short gamma-ray burst (GRB) 170817A. Multi-wavelength follow-up observations were carried out, and X-ray, optical, and radio counterparts to GW170817 were detected. The observations undoubtedly indicate that GRB 170817A originates from a binary neutron star merger. However, the GRB falls into the low-luminosity class that could have a higher statistical occurrence rate and detection probability than the normal (high-luminosity) class. This implies the possibility that GRB 170817A is intrinsically powerful, but we are off-axis and only observe its side emission. In this Letter, we provide a timely modeling of the multi-wavelength afterglow emission from this GRB and the associated kilonova signal from the merger ejecta, under the assumption of a structured jet, a two-component jet, and an intrinsically less-energetic quasi-isotropic fireball, respectively. Comparing the afterglow properties with the multi-wavelength follow-up observations, we can distinguish between these three models. Furthermore, a few model parameters (e.g., the ejecta mass and velocity) can be constrained.

Photometric and Spectroscopic Observations of GRB 140629A

NASA Astrophysics Data System (ADS)

Xin, Li-Ping; Zhong, Shu-Qing; Liang, En-Wei; Wang, Jing; Liu, Hao; Zhang, Tian-Meng; Huang, Xiao-Li; Li, Hua-Li; Qiu, Yu-Lei; Han, Xu-Hui; Wei, Jian-Yan

2018-06-01

We present our optical photometric and spectroscopical observations of GRB 140629A. A redshift of z = 2.275 ±0.043 is measured through the metal absorption lines in our spectroscopic data. Using our photometric data and multiple observational data from other telescopes, we show that its optical light curve is well interpreted with the standard forward shock models in the thin shell case. Its optical–X-ray afterglow spectrum is jointly fitted with a single power-law function, yielding a photon index of ‑1.90 ± 0.05. The optical extinction and neutral hydrogen absorption of the gamma-ray burst (GRB) host galaxy are negligible. The fit to the light curve with the standard models shows that the ambient density is 60 ± 9 cm‑3 and the GRB radiating efficiency is as low as ∼0.24%, likely indicating a baryonic-dominated ejecta of this GRB. This burst agrees well with the {L}{{p},{iso}}{--}{E}p{\\prime }{--}{{{Γ }}}0 relation, but confidently violates those empirical relations involving geometric corrections (or jet break time). This gives rise to an issue of the possible selection effect on these relations since the jet opening angle of this GRB is extremely narrow (0.04 rad).

Expanding relativistic shells and gamma-ray burst temporal structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fenimore, E.E.; Madras, C.D.; Nayakshin, S.

1996-12-01

Many models of gamma-ray bursts (GRBs) involve a shell expanding at extreme relativistic speeds. The shell of material expands in a photon-quiet phase for a period {ital t}{sub 0} and then becomes gamma-ray active, perhaps due to inhomogeneities in the interstellar medium or the generation of shocks. Based on kinematics, we relate the envelope of the emission of the event to the characteristics of the photon-quiet and photon-active phases. We initially assume local spherical symmetry wherein, on average, the same conditions prevail over the shell`s surface within angles the order of {Gamma}{sup {minus}1}, where {Gamma} is the Lorentz factor formore » the bulk motion. The contribution of the curvature to the temporal structure is comparable to the contribution from the overall expansion. As a result, GRB time histories from a shell should have an envelope similar to {open_quotes}FRED{close_quotes} (fast rise, exponential decay) events in which the rise time is related to the duration of the photon-active phase and the fall time is related to the duration of the photon-quiet phase. This result depends only on local spherical symmetry and, since most GRBs do not have such envelopes, we introduce the {open_quotes}shell symmetry{close_quotes} problem: the observed time history envelopes of most GRBs do not agree with that expected for a relativistic expanding shell. Although FREDs have the signature of a relativistic shell, they may not be due to a single shell, as required by some cosmological models. Some FREDs have precursors in which the peaks are separated by more than the expansion time required to explain FRED shape. Such a burst is most likely explained by a central engine; that is, the separation of the multiple peaks occurs because the central site produced multiple releases of energy on timescales comparable to the duration of the event. (Abstract Truncated)« less

On the nature of the extremely fast optical rebrightening of the afterglow of GRB 081029

NASA Astrophysics Data System (ADS)

Nardini, M.; Greiner, J.; Krühler, T.; Filgas, R.; Klose, S.; Afonso, P.; Clemens, C.; Guelbenzu, A. N.; Olivares E., F.; Rau, A.; Rossi, A.; Updike, A.; Küpcü Yoldaş, A.; Yoldaş, A.; Burlon, D.; Elliott, J.; Kann, D. A.

2011-07-01

Context. After the launch of the Swift satellite, the gamma-ray burst (GRB) optical light-curve smoothness paradigm has been questioned thanks to the faster and better sampled optical follow-up, which has unveiled a very complex behaviour. This complexity is triggering the interest of the whole GRB community. The GROND multi-channel imager is used to study optical and near-infrared (NIR) afterglows of GRBs with unprecedented optical and near-infrared temporal and spectral resolution. The GRB 081029 has a very prominent optical rebrightening event and is an outstanding example of the application of the multi-channel imager to GRB afterglows. Aims: Here we exploit the rich GROND multi-colour follow-up of GRB 081029 combined with XRT observations to study the nature of late-time rebrightenings that appear in the optical-NIR light-curves of some GRB afterglows. Methods: We analyse the optical and NIR observations obtained with the seven-channel Gamma-Ray burst Optical and Near-infrared Detector (GROND) at the 2.2 m MPI/ESO telescope and the X-ray data obtained with the XRT telescope on board the Swift observatory. The multi-wavelength temporal and spectral evolution is discussed in the framework of different physical models. Results: The extremely steep optical and NIR rebrightening observed in GRB 081029 cannot be explained in the framework of the standard forward shock afterglow model. The absence of a contemporaneous X-ray rebrightening and the evidence of a strong spectral evolution in the optical-NIR bands during the rise suggest two separate components that dominate in the early and late-time light-curves, respectively. The steepness of the optical rise cannot be explained even in the framework of the alternative scenarios proposed in the literature unless a late-time activity of the central engine is assumed. Full GROND photometry of GRB 081029 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/531/A39

Ginsenoside Rb1 improves energy metabolism in the skeletal muscle of an animal model of postoperative fatigue syndrome.

PubMed

Tan, Shan-Jun; Li, Ning; Zhou, Feng; Dong, Qian-Tong; Zhang, Xiao-Dong; Chen, Bi-Cheng; Yu, Zhen

2014-10-01

Postoperative fatigue syndrome (POFS) is a common clinical complication followed by almost every major abdominal surgery. Ginsenoside Rb1 (GRb1), a principle ginsenoside in ginseng, could exert a potent anti-fatigue effect on POFS. However, the mechanism is still unknown. Previous studies revealed that alterations in the energy metabolism in the skeletal muscle may play a vital role in the development and progression of fatigue. In the present study, we investigate the effect of GRb1 on energy metabolism in the skeletal muscle of a rat model of POFS induced by major small intestinal resection. GRb1 (10 mg/kg) was intraperitoneally administrated once daily for 1, 3, 7, and 10 d from the operation day, respectively. The locomotor activity was recorded every day, and total food intake was calculated starting from 24 h after surgery. After GRb1 treatment was completed, blood and skeletal muscle were sampled. The level of blood glucose was determined by an automatic biochemical analyzer. The content of adenosine triphosphate (ATP) in skeletal muscle was determined by high-performance liquid chromatography. The activity of energy metabolic enzymes Na(+)-K(+)-ATPase, pyruvate kinase, and succinate dehydrogenase (SDH) was assessed by commercially available kits. The results revealed that GRb1 could increase locomotor activity of POFS rats and significantly increase their total food intake postoperatively (P < 0.05). Furthermore, GRb1 also significantly increased ATP content in the skeletal muscle of POFS rats (P < 0.05). Meanwhile, the activity of Na(+)-K(+)-ATPase and SDH in the skeletal muscle of POFS rats was enhanced by GRb1 (P < 0.05). However, no significant differences in blood glucose and pyruvate kinase were found between the POFS and GRb1 treatment rats (P > 0.05). These results suggest that GRb1 may improve skeletal muscle energy metabolism in POFS, and the underlying mechanism may be associated with an increase in the content of ATP and an enhancement in the activity of energy metabolic enzymes such as Na(+)-K(+)-ATPase ATPase and SDH in the skeletal muscle. Copyright © 2014 Elsevier Inc. All rights reserved.

A Different Point of View towards GRB 031203

NASA Technical Reports Server (NTRS)

Ramirez-Ruiz, E.; Granot, J.; Kouveliotou, C.; Woosley, S. E.; Patel, S. K.; Mazzali, P. A.

2004-01-01

One of the most fundamental characteristics of any explosion is its energy, yet despite lively debates, the gamma-ray burst (GRB) community has still to reach a consensus on whether GRBs are standard bombs with a total energy in their relativistic ejecta approximately 10(exp 51) ergs, or a broad range of phenomena with energies varying by many orders of magnitude. While low energy GRBs may well exist, we show here that observations of GRB 031203, do not require a sub-energetic nature for that event. In fact, contrary to previous claims, the data are more consistent with a typical, powerful GRB seen at an angle of about twice the opening angle of the central jet.

GRB 080503: IMPLICATIONS OF A NAKED SHORT GAMMA-RAY BURST DOMINATED BY EXTENDED EMISSION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perley, D. A.; Metzger, B. D.; Butler, N. R.

We report on observations of GRB 080503, a short gamma-ray burst (GRB) with very bright extended emission (about 30 times the gamma-ray fluence of the initial spike) in conjunction with a thorough comparison to other short Swift events. In spite of the prompt-emission brightness, however, the optical counterpart is extraordinarily faint, never exceeding 25 mag in deep observations starting at {approx}1 hr after the Burst Alert Telescope (BAT) trigger. The optical brightness peaks at {approx}1 day and then falls sharply in a manner similar to the predictions of Li and Paczynski (1998) for supernova-like emission following compact binary mergers. However,more » a shallow spectral index and similar evolution in X-rays inferred from Chandra observations are more consistent with an afterglow interpretation. The extreme faintness of this probable afterglow relative to the bright gamma-ray emission argues for a very low density medium surrounding the burst (a 'naked' GRB), consistent with the lack of a coincident host galaxy down to 28.5 mag in deep Hubble Space Telescope imaging. The late optical and X-ray peak could be explained by a slightly off-axis jet or by a refreshed shock. Our observations reinforce the notion that short GRBs generally occur outside regions of active star formation, but demonstrate that in some cases the luminosity of the extended prompt emission can greatly exceed that of the short spike, which may constrain theoretical interpretation of this class of events. This extended emission is not the onset of an afterglow, and its relative brightness is probably either a viewing-angle effect or intrinsic to the central engine itself. Because most previous BAT short bursts without observed extended emission are too faint for this signature to have been detectable even if it were present at typical level, conclusions based solely on the observed presence or absence of extended emission in the existing Swift sample are premature.« less

Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

NASA Astrophysics Data System (ADS)

Mao, Jirong; Wang, Jiancheng

2017-04-01

Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radio bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.

A novel explosive process is required for the gamma-ray burst GRB 060614.

PubMed

Gal-Yam, A; Fox, D B; Price, P A; Ofek, E O; Davis, M R; Leonard, D C; Soderberg, A M; Schmidt, B P; Lewis, K M; Peterson, B A; Kulkarni, S R; Berger, E; Cenko, S B; Sari, R; Sharon, K; Frail, D; Moon, D-S; Brown, P J; Cucchiara, A; Harrison, F; Piran, T; Persson, S E; McCarthy, P J; Penprase, B E; Chevalier, R A; MacFadyen, A I

2006-12-21

Over the past decade, our physical understanding of gamma-ray bursts (GRBs) has progressed rapidly, thanks to the discovery and observation of their long-lived afterglow emission. Long-duration (> 2 s) GRBs are associated with the explosive deaths of massive stars ('collapsars', ref. 1), which produce accompanying supernovae; the short-duration (< or = 2 s) GRBs have a different origin, which has been argued to be the merger of two compact objects. Here we report optical observations of GRB 060614 (duration approximately 100 s, ref. 10) that rule out the presence of an associated supernova. This would seem to require a new explosive process: either a massive collapsar that powers a GRB without any associated supernova, or a new type of 'engine', as long-lived as the collapsar but without a massive star. We also show that the properties of the host galaxy (redshift z = 0.125) distinguish it from other long-duration GRB hosts and suggest that an entirely new type of GRB progenitor may be required.

The Macronova in GRB 050709 and the GRB-macronova connection

PubMed Central

Jin, Zhi-Ping; Hotokezaka, Kenta; Li, Xiang; Tanaka, Masaomi; D'Avanzo, Paolo; Fan, Yi-Zhong; Covino, Stefano; Wei, Da-Ming; Piran, Tsvi

2016-01-01

GRB 050709 was the first short Gamma-ray Burst (sGRB) with an identified optical counterpart. Here we report a reanalysis of the publicly available data of this event and the discovery of a Li-Paczynski macronova/kilonova that dominates the optical/infrared signal at t>2.5 days. Such a signal would arise from 0.05 r-process material launched by a compact binary merger. The implied mass ejection supports the suggestion that compact binary mergers are significant and possibly main sites of heavy r-process nucleosynthesis. Furthermore, we have reanalysed all afterglow data from nearby short and hybrid GRBs (shGRBs). A statistical study of shGRB/macronova connection reveals that macronova may have taken place in all these GRBs, although the fraction as low as 0.18 cannot be ruled out. The identification of two of the three macronova candidates in the I-band implies a more promising detection prospect for ground-based surveys. PMID:27659791

Confronting GRB prompt emission with a model for subphotospheric dissipation

DOE PAGES

Ahlgren, Björn; Larsson, Josefin; Nymark, Tanja; ...

2015-09-16

The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. We fit Fermi GRB data with a photospheric emission model which includes dissipation of the jet kinetic energy below the photosphere. The resulting spectra are dominated by Comptonization and contain no significant contribution from synchrotron radiation. In order to fit to the data, we span a physically motivated part of the model's parameter space and create DREAM (Dissipation with Radiative Emission as A table Model), a table model for XSPEC. Here, we show that this model can describemore » different kinds of GRB spectra, including GRB 090618, representing a typical Band function spectrum, and GRB 100724B, illustrating a double peaked spectrum, previously fitted with a Band+blackbody model, suggesting they originate from a similar scenario. We also suggest that the main difference between these two types of bursts is the optical depth at the dissipation site.« less

The Swift GRB Host Galaxy Legacy Survey

NASA Astrophysics Data System (ADS)

Perley, Daniel

2015-08-01

I will describe the Swift Host Galaxy Legacy Survey (SHOALS), a comprehensive multiwavelength program to characterize the demographics of the GRB host population and its redshift evolution from z=0 to z=7. Using unbiased selection criteria we have designated a subset of 119 Swift gamma-ray bursts which are now being targeted with intensive observational follow-up. Deep Spitzer imaging of every field has already been obtained and analyzed, with major programs ongoing at Keck, GTC, Gemini, VLT, and Magellan to obtain complementary optical/NIR photometry and spectroscopy to enable full SED modeling and derivation of fundamental physical parameters such as mass, extinction, and star-formation rate. Using these data I will present an unbiased measurement of the GRB host-galaxy luminosity and mass distributions and their evolution with redshift, compare GRB hosts to other star-forming galaxy populations, and discuss implications for the nature of the GRB progenitor and the ability of GRBs to serve as tools for measuring and studying cosmic star-formation in the distant universe.

Missing GRB host galaxies in deep mid-infrared observations: implications on the use of GRBs as star formation tracers

NASA Astrophysics Data System (ADS)

Le Floc'h, Emeric; Charmandaris, Vassilis; Forrest, Bill; Mirabel, Félix; Armus, Lee; Devost, Daniel

2006-05-01

We report on the first mid-infrared observations of 16 GRB host galaxies performed with the Spitzer Space Telescope, and investigate the presence of evolved stellar populations and dust-enshrouded star-forming activity associated with GRBs. Only a very small fraction of our sample is detected by Spitzer, which is not consistent with recent works suggesting the presence of a GRB host population dominated by massive and strongly-starbursting galaxies (SFR >~ 100Msolaryr-1). Should the GRB hosts be representative of star-forming galaxies at high redshift, models of galaxy evolution indicate that >~ 50% of GRB hosts would be easily detected at the depth of our mid-infrared observations. Unless our sample suffers from a strong observational bias which remains to be understood, we infer in this context that the GRBs identified with the current techniques can not be directly used as unbiased probes of the global and integrated star formation history of the Universe.

Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Jirong; Wang, Jiancheng, E-mail: jirongmao@mail.ynao.ac.cn

Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radiomore » bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.« less

Integrin-mediated signal transduction linked to Ras pathway by GRB2 binding to focal adhesion kinase.

PubMed

Schlaepfer, D D; Hanks, S K; Hunter, T; van der Geer, P

The cytoplasmic focal adhesion protein-tyrosine kinase (FAK) localizes with surface integrin receptors at sites where cells attach to the extracellular matrix. Increased FAK tyrosine phosphorylation occurs upon integrin engagement with fibronectin. Here we show that adhesion of murine NIH3T3 fibroblasts to fibronectin promotes SH2-domain-mediated association of the GRB2 adaptor protein and the c-Src protein-tyrosine kinase (PTK) with FAK in vivo, and also results in activation of mitogen-activated protein kinase (MAPK). In v-Src-transformed NIH3T3, the association of v-Src, GRB2 and Sos with FAK is independent of cell adhesion to fibronectin. The GRB2 SH2 domain binds directly to tyrosine-phosphorylated FAK. Mutation of tyrosine residue 925 of FAK (YENV motif) to phenylalanine blocks GRB2 SH2-domain binding to FAK in vitro. Our results show that fibronectin binding to integrins on NIH3T3 fibroblasts promotes c-Src and FAK association and formation of an integrin-activated signalling complex. Phosphorylation of FAK at Tyr 925 upon fibronectin stimulation creates an SH2-binding site for GRB2 which may link integrin engagement to the activation of the Ras/MAPK signal transduction pathway.

The high-redshift gamma-ray burst GRB 140515A

DOE PAGES

Melandri, A.; Bernardini, M. G.; D'Avanzo, P. D.; ...

2015-09-09

High-redshift gamma-ray bursts (GRBs) offer several advantages when studying the distant Universe, providing unique information about the structure and properties of the galaxies in which they exploded. Spectroscopic identification with large ground-based telescopes has improved our knowledge of this kind of distant events. We present the multi-wavelength analysis of the high-zSwift GRB GRB 140515A (z = 6.327). The best estimate of the neutral hydrogen fraction of the intergalactic medium towards the burst is x HI ≤ 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded inmore » a very low-density environment. Its circum-burst medium is characterised by an average extinction (AV ~ 0.1) that seems to be typical of z ≥ 6 events. The observed multi-band light curves are explained either with a very hard injected spectrum (p = 1.7) or with a multi-component emission (p = 2.1). In the second case a long-lasting central engine activity is needed in order to explain the late time X-ray emission. Furthermore, the possible origin of GRB 140515A in a Pop III (or in a Pop II star with a local environment enriched by Pop III) massive star is unlikely.« less

Fusion protein based on Grb2-SH2 domain for cancer therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saito, Yuriko; Graduate School of Pharmaceutical Sciences, Chiba University; Furukawa, Takako, E-mail: tfuru@nirs.go.jp

2010-08-20

Research highlights: {yields} Grb2 mediates EGFR signaling through binding to phosphorylate EGFR with SH2 domain. {yields} We generated fusion proteins containing 1 or 2 SH2 domains of Grb2 added with TAT. {yields} The one with 2 SH2 domains (TSSF) interfered ERK phosphorylation. {yields} TSSF significantly delayed the growth of EGFR overexpressing tumor in a mouse model. -- Abstract: Epidermal growth factor receptor (EGFR) is one of the very attractive targets for cancer therapy. In this study, we generated fusion proteins containing one or two Src-homology 2 (SH2) domains of growth factor receptor bound protein 2 (Grb2), which bind to phosphorylatedmore » EGFR, added with HIV-1 transactivating transcription for cell membrane penetration (termed TSF and TSSF, respectively). We examined if they can interfere Grb2-mediated signaling pathway and suppress tumor growth as expected from the lack of SH3 domain, which is necessary to intermediate EGFR-Grb2 cell signaling, in the fusion proteins. The transduction efficiency of TSSF was similar to that of TSF, but the binding activity of TSSF to EGFR was higher than that of TSF. Treatment of EGFR-overexpressing cells showed that TSSF decreased p42-ERK phosphorylation, while TSF did not. Both the proteins delayed cell growth but did not induce cell death in culture. TSSF also significantly suppressed tumor growth in vivo under consecutive administration. In conclusion, TSSF showed an ability to inhibit EGFR-Grb2 signaling and could have a potential to treat EGFR-activated cancer.« less

GRB 140619B: a short GRB from a binary neutron star merger leading to black hole formation

NASA Astrophysics Data System (ADS)

Ruffini, R.; Muccino, M.; Kovacevic, M.; Oliveira, F. G.; Rueda, J. A.; Bianco, C. L.; Enderli, M.; Penacchioni, A. V.; Pisani, G. B.; Wang, Y.; Zaninoni, E.

2015-08-01

We show the existence of two families of short gamma-ray bursts (GRBs), both originating from the merger of binary neutron stars (NSs): family-1 with {E}{iso}\\lt {10}52 erg, leading to a massive NS as the merged core, and family-2 with {E}{iso}\\gt {10}52 erg, leading to a black hole (BH). Following the identification of the prototype GRB 090227B, we present the details of a new example of family-2 short burst: GRB 140619B. From the spectral analysis of the early ˜0.2 s, we infer an observed temperature {kT}=(324+/- 33) keV of the {{{e}}}+{{{e}}}--plasma at transparency (P-GRB), a theoretically derived redshift z=2.67+/- 0.37, a total burst energy {E}{{{e}}+{{{e}}}-}{tot}=(6.03+/- 0.79)× {10}52 erg, a rest-frame peak energy {E}p,i=4.7 MeV, and a baryon load B=(5.52+/- 0.73)× {10}-5. We also estimate the corresponding emission of gravitational waves. Two additional examples of family-2 short bursts are identified: GRB 081024B and GRB 090510, remarkable for its well determined cosmological distance. We show that marked differences exist in the nature of the afterglows of these two families of short bursts: family-2 bursts, leading to BH formation, consistently exhibit high energy emission following the proper-GRB emission; family-1 bursts, leading to the formation of a massive NS, should never exhibit high energy emission. We also show that both the families fulfill an {E}p,i-Eiso relation with slope γ =0.59+/- 0.07 and a normalization constant incompatible with the one for long GRBs. The observed rate of such family-2 events is {ρ }0=≤ft({2.1}-1.4+2.8\\right)× {10}-4 Gpc-3 yr-1.

Evidence for in vivo phosphorylation of the Grb2 SH2-domain binding site on focal adhesion kinase by Src-family protein-tyrosine kinases.

PubMed

Schlaepfer, D D; Hunter, T

1996-10-01

Focal adhesion kinase (FAK) is a nonreceptor protein-tyrosine kinase (PTK) that associates with integrin receptors and participates in extracellular matrix-mediated signal transduction events. We showed previously that the c-Src nonreceptor PTK and the Grb2 SH2/SH3 adaptor protein bound directly to FAK after fibronectin stimulation (D. D. Schlaepfer, S.K. Hanks, T. Hunter, and P. van der Geer, Nature [London] 372:786-791, 1994). Here, we present evidence that c-Src association with FAK is required for Grb2 binding to FAK. Using a tryptic phosphopeptide mapping approach, the in vivo phosphorylation of the Grb2 binding site on FAK (Tyr-925) was detected after fibronectin stimulation of NIH 3T3 cells and was constitutively phosphorylated in v-Src-transformed NIH 3T3 cells. In vitro, c-Src phosphorylated FAK Tyr-925 in a glutathione S-transferase-FAK C-terminal domain fusion protein, whereas FAK did not. Using epitope-tagged FAK constructs, transiently expressed in human 293 cells, we determined the effect of site-directed mutations on c-Src and Grb2 binding to FAK. Mutation of FAK Tyr-925 disrupted Grb2 binding, whereas mutation of the c-Src binding site on FAK (Tyr-397) disrupted both c-Src and Grb2 binding to FAK in vivo. These results support a model whereby Src-family PTKs are recruited to FAK and focal adhesions following integrin-induced autophosphorylation and exposure of FAK Tyr-397. Src-family binding and phosphorylation of FAK at Tyr-925 creates a Grb2 SH2-domain binding site and provides a link to the activation of the Ras signal transduction pathway. In Src-transformed cells, this pathway may be constitutively activated as a result of FAK Tyr-925 phosphorylation in the absence of integrin stimulation.

GRB 021211 as a Faint Analogue of GRB 990123: Exploring the Similarities and Differences in the Optical Afterglows

NASA Technical Reports Server (NTRS)

Holland, Stephen T.; Bersier, David; Bloom, J. S.; Garnavich, Peter M.; Caldwell, Nelson; Challis, Peter; Kirshner, Robert; Luhman, Kevin; McLeod, Brian; Stanek, K. Z.

2004-01-01

We present BVR(sub c)JHK(sub s) photometry of the optical afterglow of the gamma-ray burst GRB 021211 taken at the Magellan, MMT, and WIYN observatories between 0.7 and 50 days after the burst. We find an intrinsic spectral slope at optical and near-infrared wavelengths of 0.69 +/- 0.14 at 0.87 days. The optical decay during the first day is almost identical to that of GRB 990123 except that GRB 021211's optical afterglow was intrinsically approximately 38 times fainter and the transition from the reverse shock to the forward shock may have occurred earlier than it did for GRB 990123. We find no evidence for a jet break or the cooling break passing through optical frequencies during the first day after the burst. There is weak evidence for a break in the J-band decay between 0.89 and 1.87 days which may be due to a jet. The optical and infrared data are consistent with a relativistic fireball where the shocked electrons are in the slow cooling regime and the electron index is 2.3 +/- 0.1. The burst appears to have occurred in a homogeneous ambient medium. Our analysis suggests that the jet of GRB 021211 may have a small opening angle (1.4 deg-4.4 deg) and that the total gamma-ray energy is much less than the canonical value of 1.33 x 10(exp 51) erg. If, this is the case then most of the energy of the burst may be in another form such as a frozen magnetic field, in supernova ejecta, or in a second jet component. The host galaxy of GRB 021211 is subluminous and has a star formation rate of at least 1 solar mass/yr.

In Search of Progenitors for Supernovaless Gamma-Ray Bursts 060505 and 060614: Re-examination of Their Afterglows

NASA Astrophysics Data System (ADS)

Xu, D.; Starling, R. L. C.; Fynbo, J. P. U.; Sollerman, J.; Yost, S.; Watson, D.; Foley, S.; O'Brien, P. T.; Hjorth, J.

2009-05-01

GRB 060505 and GRB 060614 are nearby long-duration gamma-ray bursts (LGRBs) without accompanying supernovae (SNe) down to very strict limits. They thereby challenge the conventional LGRB-SN connection and naturally give rise to the question: are there other peculiar features in their afterglows which would help shed light on their progenitors? To answer this question, we combine new observational data with published data and investigate the multiband temporal and spectral properties of the two afterglows. We find that both afterglows can be well interpreted within the framework of the jetted standard external shock wave model, and that the afterglow parameters for both bursts fall well within the range observed for other LGRBs. Hence, from the properties of the afterglows there is nothing to suggest that these bursts should have another progenitor than other LGRBs. Recently, Swift-discovered GRB 080503 also has the spike + tail structure during its prompt γ-ray emission seemingly similar to GRB 060614. We analyze the prompt emission of this burst and find that this GRB is actually a hard-spike + hard-tail burst with a spectral lag of 0.8 ± 0.4 s during its tail emission. Thus, the properties of the prompt emission of GRB 060614 and GRB 080503 are clearly different, motivating further thinking of GRB classification (and even identification of faint core-collapse SNe). Finally, we note that, whereas the progenitor of the two SN-less bursts remains uncertain, the core-collapse origin for the SN-less bursts would be quite certain if a windlike environment can be observationally established, e.g., from an optical decay faster than the X-ray decay in the afterglow's slow cooling phase. Based on observations collected at the European Organization for Astronomical Research in the Southern Hemisphere, Chile, under programs 077.D-0661 and 177.A-0591.

GRB 161219B/SN 2016jca: A low-redshift gamma-ray burst supernova powered by radioactive heating

NASA Astrophysics Data System (ADS)

Cano, Z.; Izzo, L.; de Ugarte Postigo, A.; Thöne, C. C.; Krühler, T.; Heintz, K. E.; Malesani, D.; Geier, S.; Fuentes, C.; Chen, T.-W.; Covino, S.; D'Elia, V.; Fynbo, J. P. U.; Goldoni, P.; Gomboc, A.; Hjorth, J.; Jakobsson, P.; Kann, D. A.; Milvang-Jensen, B.; Pugliese, G.; Sánchez-Ramírez, R.; Schulze, S.; Sollerman, J.; Tanvir, N. R.; Wiersema, K.

2017-09-01

Since the first discovery of a broad-lined type Ic supernova (SN) with a long-duration gamma-ray burst (GRB) in 1998, fewer than fifty GRB-supernovae (SNe) have been discovered. The intermediate-luminosity Swift GRB 161219B and its associated supernova SN 2016jca, which occurred at a redshift of z = 0.1475, represents only the seventh GRB-SN to have been discovered within 1 Gpc, and hence provides an excellent opportunity to investigate the observational and physical properties of these very elusive and rare type of SN. As such, we present optical to near-infrared photometry and optical spectroscopy of GRB 161219B and SN 2016jca, spanning the first three months since its discovery. GRB 161219B exploded in the disk of an edge-on spiral galaxy at a projected distance of 3.4 kpc from the galactic centre. GRB 161219B itself is an outlier in the Ep,I - Eγ,iso plane, while SN 2016jca had a rest-frame, peak absolute V-band magnitude of MV = - 19.0 ± 0.1, which it reached after 12.3 ± 0.7 rest-frame days. We find that the bolometric properties of SN 2016jca are inconsistent with being powered solely by a magnetar central engine, and demonstrate that it was likely powered exclusively by energy deposited by the radioactive decay of nickel and cobalt into their daughter products, which were nucleosynthesised when its progenitor underwent core collapse. We find that 0.22 ± 0.08M⊙ of nickel is required to reproducethe peak luminosity of SN 2016jca, and we constrain an ejecta mass of 5.8 ± 0.3M⊙ and a kinetic energy of 5.1 ± 0.8 × 1052 erg. Finally, we report on a chromatic, pre-maximum bump in the g-band light curve, and discuss its possible origin.

Aspects of T-Dually Extended Superspaces

NASA Astrophysics Data System (ADS)

Polacek, Martin

This dissertation is divided into three main parts where we derive various properties of the T-dually extended superspaces. In the first part we reformulate the manifestly T-dual description of the massless sector of the closed bosonic string, directly from the geometry associated with the (left and right) affine Lie algebra of the coset space Poincare/Lorentz. This construction initially doubles not only the (space-time) coordinates for translations but also those for Lorentz transformations (and their "dual"). As a result, the Lorentz connection couples directly to the string (as does the vielbein), rather than being introduced indirectly through covariant derivatives as previously. This not only reproduces the old definition of T-dual torsion, but automatically gives a general, covariant definition of T-dual curvature (but still with some undetermined connections). In the second part we give the manifestly T-dual formulation of the massless sector of the classical 3D Type II superstring in off-shell 3D N = 2 superspace, including the action. It has a simple relation to the known superspace of 4D N = 1 supergravity in 4D M-theory via 5D F-theory. The pre-potential appears as part of the vielbein, without derivatives. In the last and the most involved part we find the pre-potential in the superspace with AdS5 x S5 background. The pre-potential appears as part of the vielbeins, without derivatives. In both subspaces (AdS5 and S 5) we use Poincare coordinates. We pick one bulk coordinate in AdS5 and one bulk coordinate in S 5 to define the space-cone gauge. Such space-cone gauge destroys the bulk Lorentz covariance. However, it still preserves boundary Lorentz covariance (and gives projective superspace) SO ( 3, 1) ⊗ SO (4) and so symmetries of boundary CFT are manifest.

The Observer's Guide to the Gamma-Ray Burst-Supernova Connection

NASA Astrophysics Data System (ADS)

Cano, Z.

2016-10-01

In this review we present a progress report of the connection between long-duration gamma-ray bursts (GRBs) and their accompanying supernovae (SNe). The analysis is from the point of view of an observer, with much of the emphasis placed on how observations, and the modelling of observations, have constrained what we known about GRB-SNe. We discuss their photometric and spectroscopic properties, their role as cosmological probes, including their measured luminosity-decline relationships, and how they can be used to measure the Hubble constant. We present a statistical analysis of their bolometric properties, and use this to determine the properties of the "average" GRB-SNe: which has a kinetic energy of EK≈2.5×10^52 erg, an ejecta mass of Mej≈6 M⊙, a nickel mass of MNi≈0.4 M⊙, a peak photospheric velocity of vph≈21,000 km s-1, a peak bolometric luminosity of Lp≈1×10^43 erg s-1, and it reaches peak bolometric light in tp≈13 days. We discuss their geometry, consider the various physical processes that are thought to power the luminosity of GRB-SNe, and whether differences exist between GRB-SNe and the SNe associated with ultra-long duration GRBs. We discuss how observations of the environments of GRB-SNe further constrain the physical properties of their progenitor stars, and give an overview of the current theoretical paradigms of their suspected central engines. We also present an overview of the radioactively powered transients that have been photometrically associated with short-duration GRBs. We conclude the review by discussing what additional research is needed to further our understanding of GRB-SNe, in particular the role of binary-formation channels and the connection of GRB-SNe with superluminous SNe (abridged).

Structural and biophysical investigation of the interaction of a mutant Grb2 SH2 domain (W121G) with its cognate phosphopeptide.

PubMed

Papaioannou, Danai; Geibel, Sebastian; Kunze, Micha B A; Kay, Christopher W M; Waksman, Gabriel

2016-03-01

The adaptor protein Grb2 is a key element of mitogenetically important signaling pathways. With its SH2 domain it binds to upstream targets while its SH3 domains bind to downstream proteins thereby relaying signals from the cell membranes to the nucleus. The Grb2 SH2 domain binds to its targets by recognizing a phosphotyrosine (pY) in a pYxNx peptide motif, requiring an Asn at the +2 position C-terminal to the pY with the residue either side of this Asn being hydrophobic. Structural analysis of the Grb2 SH2 domain in complex with its cognate peptide has shown that the peptide adopts a unique β-turn conformation, unlike the extended conformation that phosphopeptides adopt when bound to other SH2 domains. TrpEF1 (W121) is believed to force the peptide into this unusual conformation conferring this unique specificity to the Grb2 SH2 domain. Using X-ray crystallography, electron paramagnetic resonance (EPR) spectroscopy, and isothermal titration calorimetry (ITC), we describe here a series of experiments that explore the role of TrpEF1 in determining the specificity of the Grb2 SH2 domain. Our results demonstrate that the ligand does not adopt a pre-organized structure before binding to the SH2 domain, rather it is the interaction between the two that imposes the hairpin loop to the peptide. Furthermore, we find that the peptide adopts a similar structure when bound to both the wild-type Grb2 SH2 domain and a TrpEF1Gly mutant. This suggests that TrpEF1 is not the determining factor for the conformation of the phosphopeptide. © 2015 The Protein Society.

DDC and COBL, flanking the imprinted GRB10 gene on 7p12, are biallelically expressed.

PubMed

Hitchins, Megan P; Bentley, Louise; Monk, David; Beechey, Colin; Peters, Jo; Kelsey, Gavin; Ishino, Fumitoshi; Preece, Michael A; Stanier, Philip; Moore, Gudrun E

2002-12-01

Maternal duplication of human 7p11.2-p13 has been associated with Silver-Russell syndrome (SRS) in two familial cases. GRB10 is the only imprinted gene identified within this region to date. GRB10 demonstrates an intricate tissue- and isoform-specific imprinting profile in humans, with paternal expression in fetal brain and maternal expression of one isoform in skeletal muscle. The mouse homolog is maternally transcribed. The GRB10 protein is a potent growth inhibitor and represents a candidate for SRS, which is characterized by pre- and postnatal growth retardation and a spectrum of additional dysmorphic features. Since imprinted genes tend to be grouped in clusters, we investigated the imprinting status of the dopa-decarboxylase gene (DDC) and the Cordon-bleu gene (COBL) which flank GRB10 within the 7p11.2-p13 SRS duplicated region. Although both genes were found to replicate asynchronously, suggestive of imprinting, SNP expression analyses showed that neither gene was imprinted in multiple human fetal tissues. The mouse homologues, Ddc and Cobl, which map to the homologous imprinted region on proximal Chr 11, were also biallelically expressed in mice with uniparental maternal or paternal inheritance of this region. With the intent of using mouse Grb10 as an imprinted control, biallelic expression was consistently observed in fetal, postnatal, and adult brain of these mice, in contrast to the maternal-specific transcription previously demonstrated in brain in inter-specific F1 progeny. This may be a further example of over-expression of maternally derived transcripts in inter-specific mouse crosses. GRB10 remains the only imprinted gene identified within 7p11.2-p13.

Growth of chronic myeloid leukemia cells is inhibited by infection with Ad-SH2-HA adenovirus that disrupts Grb2-Bcr-Abl complexes.

PubMed

Peng, Zhi; Luo, Hong-Wei; Yuan, Ying; Shi, Jing; Huang, Shi-Feng; Li, Chun-Li; Cao, Wei-Xi; Huang, Zong-Gan; Feng, Wen-Li

2011-05-01

The persistence of Bcr-Abl-positive cells in patients on imatinib therapy indicates that inhibition of the Bcr-Abl kinase activity alone might not be sufficient to eradicate the leukemia cells. Many downstream effectors of Bcr-Abl have been described, including activation of both the Grb2-SoS-Ras-MAPK and Grb2-Gab2-PI3K-Akt pathways. The Bcr-Abl-Grb2 interaction, which is mediated by the direct interaction of the Grb2 SH2 domain with the phospho-Bcr-Abl Y177, is required for activation of these signaling pathways. Therefore, disrupting their interaction represents a potential therapeutic strategy for inhibiting the oncogenic downstream signals of Bcr-Abl. Adenovirus Ad-SH2-HA expressing the Grb2 SH2 domain was constructed and applied in this study. As expected, Ad-SH2-HA efficiently infected CML cells and functioned by binding to the phospho-Bcr-Abl Y177 site, competitively disrupting the Grb2 SH2-phospho-Bcr-Abl Y177 complex. They induced potent anti-proliferation and apoptosis-inducing effects in CML cell lines. Moreover, the Ras, MAPK and Akt activities were significantly reduced in the Ad-SH2-HA treated cells. These were not observed with the point-mutated control adenovirus Ad-Sm-HA with abolished phospho-Bcr-Abl Y177 binding sites. These data indicate that, in addition to the direct targeting of Bcr-Abl, selective inhibition of its downstream signaling pathways may be a therapeutic option for CML, and the Ad-SH2-HA-mediated killing strategy could be explored as a promising anti-leukemia agent in CML.

RAPTOR: Closed-Loop monitoring of the night sky and the earliest optical detection of GRB 021211

NASA Astrophysics Data System (ADS)

Vestrand, W. T.; Borozdin, K.; Casperson, D. J.; Fenimore, E.; Galassi, M.; McGowan, K.; Starr, D.; White, R. R.; Wozniak, P.; Wren, J.

2004-10-01

We discuss the RAPTOR (Rapid Telescopes for Optical Response) sky monitoring system at Los Alamos National Laboratory. RAPTOR is a fully autonomous robotic system that is designed to identify and make follow-up observations of optical transients with durations as short as one minute. The RAPTOR design is based on Biomimicry of Human Vision. The sky monitor is composed of two identical arrays of telescopes, separated by 38 kilometers, which stereoscopically monitor a field of about 1300 square-degrees for transients. Both monitoring arrays are carried on rapidly slewing mounts and are composed of an ensemble of wide-field telescopes clustered around a more powerful narrow-field telescope called the ``fovea'' telescope. All telescopes are coupled to real-time analysis pipelines that identify candidate transients and relay the information to a central decision unit that filters the candidates to find real celestial transients and command a response. When a celestial transient is found, the system can point the fovea telescopes to any position on the sky within five seconds and begin follow-up observations. RAPTOR also responds to Gamma Ray Burst (GRB) alerts generated by GRB monitoring spacecraft. Here we present RAPTOR observations of GRB 021211 that constitute the earliest detection of optical emission from that event and are the second fastest achieved for any GRB. The detection of bright optical emission from GRB021211, a burst with modest gamma-ray fluence, indicates that prompt optical emission, detectable with small robotic telescopes, is more common than previously thought. Further, the very fast decline of the optical afterglow from GRB 021211 suggests that some so-called ``optically dark'' GRBs were not detected only because of the slow response of the follow-up telescopes.

Search for GRB related prompt optical emission and other fast varying objects with ``Pi of the Sky'' detector

NASA Astrophysics Data System (ADS)

Ćwiok, M.; Dominik, W.; Małek, K.; Mankiewicz, L.; Mrowca-Ciułacz, J.; Nawrocki, K.; Piotrowski, L. W.; Sitek, P.; Sokołowski, M.; Wrochna, G.; Żarnecki, A. F.

2007-06-01

Experiment “Pi of the Sky” is designed to search for prompt optical emission from GRB sources. 32 CCD cameras covering 2 steradians will monitor the sky continuously. The data will be analysed on-line in search for optical flashes. The prototype with 2 cameras operated at Las Campanas (Chile) since 2004 has recognised several outbursts of flaring stars and has given limits for a few GRB.

Activation of the JNK pathway is essential for transformation by the Met oncogene.

PubMed

Rodrigues, G A; Park, M; Schlessinger, J

1997-05-15

The Met/Hepatocyte Growth Factor (HGF) receptor tyrosine kinase is oncogenically activated through a rearrangement that creates a hybrid gene Tpr-Met. The resultant chimeric p65(Tpr-Met) protein is constitutively phosphorylated on tyrosine residues in vivo and associates with a number of SH2-containing signaling molecules including the p85 subunit of PI-3 kinase and the Grb2 adaptor protein, which couples receptor tyrosine kinases to the Ras signaling pathway. Mutation of the binding site for Grb2 impairs the ability of Tpr-Met oncoprotein to transform fibroblasts, suggesting that the activation of the Ras/MAP kinase signaling pathway through Grb2 may be essential for cellular transformation. To test this hypothesis dominant-negative mutants of Grb2 with deletions of the SH3 domains were introduced into Tpr-Met transformed fibroblasts. Cells overexpressing the mutants were found to be morphologically reverted and exhibited reduced growth in soft agar. Surprisingly, the Grb2 mutants blocked activation of the JNK/SAPK but not MAP kinase activity induced by the Tpr-Met oncoprotein. Additionally, cells expressing dominant-negative Grb2 mutants had reduced PI-3-kinase activity and dominant-negative mutants of Rac1 blocked both Tpr-Met-induced transformation and activation of JNK. These experiments reveal a novel link between Met and the JNK pathway, which is essential for transformation by this oncogene.

In brain, Axl recruits Grb2 and the p85 regulatory subunit of Pl3 kinase; in vitro mutagenesis defines th requisite binding sites for downstream Akt activation

PubMed Central

Weinger, Jason G.; Gohari, Pouyan; Yan, Ying; Backer, Jonathan M.; Varnum, Brian; Shafit-Zagardo, Bridget

2010-01-01

Axl is a receptor tyrosine kinase implicated in cell survival following growth factor withdrawal and other stressors. The binding of Axl's ligand, growth arrest-specific protein 6 (Gas6), results in Axl autophosphorylation, recruitment of signaling molecules, and activation of downstream survival pathways. Pull-down assays and immunoprecipitations using wildtype and mutant Axl transfected cells determined that Axl directly binds growth factor receptor-bound protein 2 (Grb2) at pYVN and the p85 subunit of phosphatidylinositol-3 kinase (PI3 kinase) at two pYXXM sites (pY779 and pY821). Also, p85 can indirectly bind to Axl via an interaction between p85's second proline-rich region and the N-terminal SH3 domain of Grb2. Further, Grb2 and p85 can compete for binding at the pY821VNM site. Gas6-stimulation of Axl-transfected COS7 cells recruited activated PI3 kinase and phosphorylated Akt. An interaction between Axl, p85 and Grb2 was confirmed in brain homogenates, enriched populations of O4+ oligodendrocytes, and O4– flow-through prepared from day 10 mouse brain, indicating that cells with active Gas6/Axl signal through Grb2 and the PI3 kinase/Akt pathways. PMID:18346204

Calibration of GRB Luminosity Relations with Cosmography

NASA Astrophysics Data System (ADS)

Gao, He; Liang, Nan; Zhu, Zong-Hong

For the use of gamma-ray bursts (GRBs) to probe cosmology in a cosmology-independent way, a new method has been proposed to obtain luminosity distances of GRBs by interpolating directly from the Hubble diagram of SNe Ia, and then calibrating GRB relations at high redshift. In this paper, following the basic assumption in the interpolation method that objects at the same redshift should have the same luminosity distance, we propose another approach to calibrate GRB luminosity relations with cosmographic fitting directly from SN Ia data. In cosmography, there is a well-known fitting formula which can reflect the Hubble relation between luminosity distance and redshift with cosmographic parameters which can be fitted from observation data. Using the Cosmographic fitting results from the Union set of SNe Ia, we calibrate five GRB relations using GRB sample at z ≤ 1.4 and deduce distance moduli of GRBs at 1.4 < z ≤ 6.6 by generalizing above calibrated relations at high redshift. Finally, we constrain the dark energy parameterization models of the Chevallier-Polarski-Linder (CPL) model, the Jassal-Bagla-Padmanabhan (JBP) model and the Alam model with GRB data at high redshift, as well as with the cosmic microwave background radiation (CMB) and the baryonic acoustic oscillation (BAO) observations, and we find the ΛCDM model is consistent with the current data in 1-σ confidence region.

Could GRB170817A be really correlated to an NS-NS merging?

NASA Astrophysics Data System (ADS)

Fargion, D.; Khlopov, M. Yu.; Oliva, P.

The exciting development of gravitational wave (GW) astronomy in the correlation of LIGO and VIRGO detection of GW signals makes possible to expect registration of effects of not only binary black hole (BH) coalescence but also binary neutron star (NS) merging accompanied by electromagnetic (gamma ray burst; GRB) signal. Here we consider the possibility that an NS, merging in an NS-NS or NS-BH system might be (soon) observed in correlation with any LIGO-VIRGO GWs detection. We analyze as an example the recent case of the short GRB170817A observed by Fermi and integral. The associated optical transient (OT) source in NGC4993 implies a rare near source, a consequent averaged large rate of such events (almost) compatible with expected NS-NS merging rate. However the expected beamed GRB (or short GRB) may be mostly aligned to a different direction than ours. Therefore, even soft GRB photons, spread more than hard ones, might be hardly able to shower to us. Nevertheless, a prompt spiraling electron turbine jet in largest magnetic fields, at the base of the NS-NS collapse, might shine by its tangential synchrotron radiation in spread way with its skimming photons shining in large open disk. The consequent solid angle for such soft disk gamma radiation may be large enough to be nevertheless often observed.

GRB070610: A Curious Galactic Transient

NASA Technical Reports Server (NTRS)

Kasliwal, M. M.; Kulkrarni. S. R.; Cameron, P. B.; Nakar, E.; Ofek, E. O.; Rau, A.; Soderberg, A. M.; Campana, S.; Bloom, J. S.; Perley, D. A.;

GRB 070610: A Curious Galactic Transient

NASA Astrophysics Data System (ADS)

Kasliwal, M. M.; Cenko, S. B.; Kulkarni, S. R.; Cameron, P. B.; Nakar, E.; Ofek, E. O.; Rau, A.; Soderberg, A. M.; Campana, S.; Bloom, J. S.; Perley, D. A.; Pollack, L. K.; Barthelmy, S.; Cummings, J.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Sato, G.; Chandra, P.; Frail, D.; Fox, D. B.; Price, P. A.; Berger, E.; Grebenev, S. A.; Krivonos, R. A.; Sunyaev, R. A.

2008-05-01

GRB 070610 is a typical high-energy event with a duration of 5 s. Yet within the burst localization we detect a highly unusual X-ray and optical transient, Swift J195509.6+261406. We see high-amplitude X-ray and optical variability on very short timescales even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive optics, we identified the counterpart of Swift J195509.6+261406. Late-time optical and near-infrared imaging constrain the spectral type of the counterpart to be fainter than a K-dwarf, assuming it is of Galactic origin. It is possible that GRB 070610 and Swift J195509.6+261406 are unrelated sources. However, the absence of a typical X-ray afterglow from GRB 070610 in conjunction with the spatial and temporal coincidence of the two motivate us to suggest that the sources are related. The closest (imperfect) analog to Swift J195509.6+261406 is V4641 Sgr, an unusual black hole binary. We suggest that Swift J195509.6+261406 along with V4641 Sgr define a subclass of stellar black hole binaries—the fast X-ray novae. We further suggest that fast X-ray novae are associated with bursts of gamma rays. If so, GRB 070610 defines a new class of celestial gamma-ray bursts and these bursts dominate the long-duration GRB demographics.

A cross-correlation search for intermediate-duration gravitational waves from GRB magnetars

NASA Astrophysics Data System (ADS)

Coyne, Robert

2015-04-01

Since the discovery of the afterglow in 1997, the progress made in our understanding of gamma-ray bursts (GRBs) has been spectacular. Yet a direct proof of GRB progenitors is still missing. In the last few years, evidence for a long-lived and sustained central engine in GRBs has mounted. This has called attention to the so-called millisecond-magnetar model, which proposes that a highly magnetized, rapidly-rotating neutron star may exist at the heart of some of these events. The advent of advanced gravitational wave detectors such as LIGO and Virgo may enable us to probe directly, for the first time, the nature of GRB progenitors and their byproducts. In this context, we describe a novel application of a generalized cross-correlation technique optimized for the detection of long-duration gravitational wave signals that may be associated with bar-like deformations of GRB magnetars. The detection of these signals would allow us to answer some of the most intriguing questions on the nature of GRB progenitors, and serve as a starting point for a new class of intermediate-duration gravitational wave searches.

Implications for the Origin of GRB 051103 from LIGO Observations

NASA Astrophysics Data System (ADS)

Abadie, J.; Abbott, B. P.; Abbott, T. D.; Abbott, R.; Abernathy, M.; Adams, C.; Adhikari, R.; Affeldt, C.; Ajith, P.; Allen, B.; Allen, G. S.; Amador Ceron, E.; Amariutei, D.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Arain, M. A.; Araya, M. C.; Aston, S. M.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballmer, S.; Barker, D.; Barnum, S.; Barr, B.; Barriga, P.; Barsotti, L.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Bauchrowitz, J.; Behnke, B.; Bell, A. S.; Belopolski, I.; Benacquista, M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Biswas, R.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bondarescu, R.; Bork, R.; Born, M.; Bose, S.; Boyle, M.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Breyer, J.; Bridges, D. O.; Brinkmann, M.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brummitt, A.; Buonanno, A.; Burguet-Castell, J.; Burmeister, O.; Byer, R. L.; Cadonati, L.; Camp, J. B.; Campsie, P.; Cannizzo, J.; Cannon, K.; Cao, J.; Capano, C.; Caride, S.; Caudill, S.; Cavaglia, M.; Cepeda, C.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chelkowski, S.; Chen, Y.; Christensen, N.; Chua, S. S. Y.; Chung, S.; Chung, C. T. Y.; Clara, F.; Clark, D.; Clark, J.; Clayton, J. H.; Conte, R.; Cook, D.; Corbitt, T. R. C.; Cornish, N.; Costa, C. A.; Coughlin, M.; Coward, D. M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Cumming, A.; Cunningham, L.; Culter, R. M.; Dahl, K.; Danilishin, S. L.; Dannenberg, R.; Danzmann, K.; Das, K.; Daudert, B.; Daveloza, H.; Davies, G.; Daw, E. J.; Dayanga, T.; DeBra, D.; Degallaix, J.; Dent, T.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Palma, I.; Díaz, M.; Donovan, F.; Dooley, K. L.; Dorsher, S.; Douglas, E. S. D.; Drever, R. W. P.; Driggers, J. C.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Engel, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fairhurst, S.; Fan, Y.; Farr, B. F.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Finn, L. S.; Flanigan, M.; Foley, S.; Forsi, E.; Fotopoulos, N.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Garcia, J.; Garofoli, J. A.; Gholami, I.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Gill, C.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Graef, C.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Grosso, R.; Grote, H.; Grunewald, S.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hong, T.; Hooper, S.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hughey, B.; Husa, S.; Huttner, S. H.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kanner, J. B.; Katsavounidis, E.; Katzman, W.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Kelner, M.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, N.; Kim, H.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Korth, W. Z.; Kozak, D.; Kringel, V.; Krishnamurthy, S.; Krishnan, B.; Kuehn, G.; Kumar, R.; Kwee, P.; Landry, M.; Lantz, B.; Lastzka, N.; Lazzarini, A.; Leaci, P.; Leong, J.; Leonor, I.; Li, J.; Lindquist, P. E.; Lockerbie, N. A.; Lodhia, D.; Lormand, M.; Lu, P.; Luan, J.; Lubinski, M.; Lück, H.; Lundgren, A. P.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Mageswaran, M.; Mailand, K.; Mandel, I.; Mandic, V.; Marandi, A.; Márka, S.; Márka, Z.; Maros, E.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; McKechan, D. J. A.; Meadors, G.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Miller, J.; Mino, Y.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Moesta, P.; Mohanty, S. D.; Moraru, D.; Moreno, G.; Mossavi, K.; Mow-Lowry, C. M.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murphy, D.; Murray, P. G.; Nash, T.; Nawrodt, R.; Nelson, J.; Newton, G.; Nishizawa, A.; Nolting, D.; Nuttall, L.; O'Reilly, B.; O'Shaughnessy, R.; Ochsner, E.; O'Dell, J.; Ogin, G. H.; Oldenburg, R. G.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Pan, Y.; Pankow, C.; Papa, M. A.; Patel, P.; Pedraza, M.; Pekowsky, L.; Penn, S.; Peralta, C.; Perreca, A.; Phelps, M.; Pickenpack, M.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Podkaminer, J.; Pöld, J.; Postiglione, F.; Predoi, V.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prokhorov, L.; Puncken, O.; Quetschke, V.; Raab, F. J.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C. R.; Rankins, B.; Mohapatra, S. R. P.; Raymond, V.; Redwine, K.; Reed, C. M.; Reed, T.; Reid, S.; Reitze, D. H.; Riesen, R.; Riles, K.; Roberts, P.; Robertson, N. A.; Robinson, C.; Robinson, E. L.; Roddy, S.; Rollins, J.; Romano, J. D.; Romie, J. H.; Röver, C.; Rowan, S.; Rüdiger, A.; Ryan, K.; Sakata, S.; Sakosky, M.; Salemi, F.; Salit, M.; Sammut, L.; Sancho de la Jordana, L.; Sandberg, V.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saraf, S.; Sathyaprakash, B. S.; Sato, S.; Saulson, P. R.; Savage, R.; Schilling, R.; Schlamminger, S.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Searle, A. C.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shihan Weerathunga, T.; Shoemaker, D. H.; Sibley, A.; Siemens, X.; Sigg, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G.; Slagmolen, B. J. J.; Slutsky, J.; Smith, R.; Smith, J. R.; Smith, M. R.; Smith, N. D.; Somiya, K.; Sorazu, B.; Soto, J.; Speirits, F. C.; Stein, A. J.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stefszky, M.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Szokoly, G. P.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, J. R.; Taylor, R.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Tokmakov, K. V.; Torres, C.; Torrie, C. I.; Traylor, G.; Trias, M.; Tseng, K.; Ugolini, D.; Urbanek, K.; Vahlbruch, H.; Vaishnav, B.; Vallisneri, M.; Van Den Broeck, C.; van der Sluys, M. V.; van Veggel, A. A.; Vass, S.; Vaulin, R.; Vecchio, A.; Veitch, J.; Veitch, P. J.; Veltkamp, C.; Villar, A. E.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Wanner, A.; Ward, R. L.; Wei, P.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wen, S.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D.; Whiting, B. F.; Wilkinson, C.; Willems, P. A.; Williams, H. R.; Williams, L.; Willke, B.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, K.; Yamamoto, H.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yu, P.; Zanolin, M.; Zhang, L.; Zhang, Z.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Collaboration; Bizouard, M. A.; Dietz, A.; Guidi, G. M.; Was, M.

2012-08-01

We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst (GRB) whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6 Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at a distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. Assuming weakly beamed γ-ray emission with a jet semi-angle of 30°, we exclude a binary neutron star merger in M81 as the progenitor with a confidence of 98%. Neutron star-black hole mergers are excluded with >99% confidence. If the event occurred in M81, then our findings support the hypothesis that GRB 051103 was due to an SGR giant flare, making it one of the most distant extragalactic magnetars observed to date.

FERMI observations of high-energy gamma-ray emission from GRB 090217A

DOE PAGES

Ackermann, M.; Ajello, M.; Baldini, L.; ...

2010-06-22

The Fermi observatory is advancing our knowledge of gamma-ray bursts (GRBs) through pioneering observations at high energies, covering more than seven decades in energy with the two on-board detectors, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). Here, we report on the observation of the long GRB 090217A which triggered the GBM and has been detected by the LAT with a significance greater than 9σ. We present the GBM and LAT observations and on-ground analyses, including the time-resolved spectra and the study of the temporal profile from 8 keV up to ~1 GeV. All spectra are wellmore » reproduced by a Band model. We compare these observations to the first two LAT-detected, long bursts GRB 080825C and GRB 080916C. These bursts were found to have time-dependent spectra and exhibited a delayed onset of the high-energy emission, which are not observed in the case of GRB 090217A. We discuss some theoretical implications for the high-energy emission of GRBs.« less

The Gamma-Ray Burst ToolSHED is Open for Business

NASA Astrophysics Data System (ADS)

Giblin, Timothy W.; Hakkila, Jon; Haglin, David J.; Roiger, Richard J.

2004-09-01

The GRB ToolSHED, a Gamma-Ray Burst SHell for Expeditions in Data-Mining, is now online and available via a web browser to all in the scientific community. The ToolSHED is an online web utility that contains pre-processed burst attributes of the BATSE catalog and a suite of induction-based machine learning and statistical tools for classification and cluster analysis. Users create their own login account and study burst properties within user-defined multi-dimensional parameter spaces. Although new GRB attributes are periodically added to the database for user selection, the ToolSHED has a feature that allows users to upload their own burst attributes (e.g. spectral parameters, etc.) so that additional parameter spaces can be explored. A data visualization feature using GNUplot and web-based IDL has also been implemented to provide interactive plotting of user-selected session output. In an era in which GRB observations and attributes are becoming increasingly more complex, a utility such as the GRB ToolSHED may play an important role in deciphering GRB classes and understanding intrinsic burst properties.

Optical study of the counterpart to GRB 990712

NASA Astrophysics Data System (ADS)

Gorosabel, J.; Castro-Tirado, A. J.; Saizar, P.; Rattenbury, N. J.; Bond, I. A.; Yock, P.; Hearnshaw, J.; Kilmartin, P. M.; Muraki, Y.; Nakamura, T.; Ohnishi, K.; Reid, M.; Saito, To; Noda, S.

2000-09-01

Quasi-simultaneous BVR-band observations performed from New Zealand and Argentina ~16 hr after the burst clearly detected the optical counterpart to GR-B 990712. Based on these measurements we construct the optical multi-band spectrum. We report that the spectrum between the R and B bands follows a power law Fv~νβ with index β=-0.50+/-0.16. The spectrum is consistent with a stretch of an afterglow spectrum between the peak frequency, νm, and the cooling break, νc. The photon index derived following the model of Sari et al. (1998), p=2.36+/-0.08 is compatible with β and the power law decay, α, only if no absorption is introduced. Thus, our results support that GRB 990712 occurred in a low density region, resembling GRB 970508. .

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guiriec, S.; Kouveliotou, C.; Hartmann, D. H.

The origin of prompt emission from gamma-ray bursts (GRBs) remains to be an open question. Correlated prompt optical and γ -ray emission observed in a handful of GRBs strongly suggests a common emission region, but failure to adequately fit the broadband GRB spectrum prompted the hypothesis of different emission mechanisms for the low- and high-energy radiations. We demonstrate that our multi-component model for GRB γ -ray prompt emission provides an excellent fit to GRB 110205A from optical to γ -ray energies. Our results show that the optical and highest γ -ray emissions have the same spatial and spectral origin, whichmore » is different from the bulk of the X- and softest γ -ray radiation. Finally, our accurate redshift estimate for GRB 110205A demonstrates promise for using GRBs as cosmological standard candles.« less

Understanding Grb Physics With Multi-Wavelength Data

NASA Astrophysics Data System (ADS)

Zhang, Bing

The study of Gamma-ray bursts (GRBs) has entered a full multi-wavelength era. A rich trove of data from NASA GRB missions and ground-based follow up observations have been collected. Careful data mining with well-defined scientific objectives holds the key to address open questions in GRB physics, such as jet composition, radiation mechanism, progenitor and central engine physics. We propose to perform data analyses in the following three directions. 1. The time resolved GRB spectra have a dominant component that can be fit with a phenomenological ``Band'' function. The physical meaning of this function remains unclear. Recently we made a breakthrough in theoretical modeling, and showed that fast-cooling synchrotron radiation of electrons in a decreasing magnetic field can mimic the Band function in detector's bandpass, but differs from Band function slightly. We propose to apply this physically-motivated model to systematically fit the GRB prompt emission data collected by Fermi GBM and LAT, and test whether the dominant GRB emission mechanism is fast cooling synchrotron radiation. We will also fit time-dependent spectra with a time-dependent model to investigate whether a quasi- thermal "photosphere'' emission component is indeed needed to fit the observed spectra. This would shed light onto the unknown composition of GRB jets. By fitting the time resolved spectra, we will also constrain important physical parameters of GRB prompt emission, such as the emission site of GRBs, the strength of magnetic fields, as well as their evolution with radius. 2. Recent GRB multi-wavelength observations suggest that it is not straightforward to define the physical category of a GRB based on the traditional classification in the "duration''-"hardness'' domain. Some long-duration GRBs may not have a massive star origin, while some short-duration GRBs may instead have a massive star origin. We propose to systematically study the gamma-ray Swift/BAT, Fermi/GBM- LAT), X-ray (Swift/XRT, Chandra), and optical (ground-based and HST) properties of all short GRBs, and apply multi-wavelength observational criteria to constrain the possible progenitor(s) of them. 3. The GRB central engine is still not identified. Growing observational data and theoretical modeling suggest that at least some GRBs may host a magnetar (in contrast to a hyper-accreting black hole) central engine. We propose to carry out a statistical study of the prompt emission and afterglow properties of GRBs that show possible evidence of magnetar behavior and compare their properties with those that do not show such evidence. We will define three samples: a gold sample that show a steady X-ray emission followed by a rapid decline, which are likely powered by internal dissipation of a magnetar wind, a silver sample showing a shallow decay segment followed by a normal decay, which can be interpreted as external shock emission with a magnetar continuous energy injection into the blastwave, and a sample that includes other GRBs that do not show any evidence of magnetar. We will compare various observational properties (e.g. isotropic energy/luminosity, jet-corrected energy/luminosity, jet opening angle, peak energy) of these samples and investigate whether there are noticeable differences among these samples. The results would shed light onto the difficult problem of GRB central engine, addressing whether different engines work in GRBs, and if so, what difference. The program conforms to NASA's Strategic Plan, and will make use of the public archival data of many NASA missions, including Fermi, Swift, HST, and Chandra.

Testing local Lorentz invariance with gravitational waves

DOE PAGES

Kostelecký, V. Alan; Mewes, Matthew

2016-04-20

The effects of local Lorentz violation on dispersion and birefringence of gravitational waves are investigated. The covariant dispersion relation for gravitational waves involving gauge-invariant Lorentz violating operators of arbitrary mass dimension is constructed. The chirp signal from the gravitational wave event GW150914 is used to place numerous first constraints on gravitational Lorentz violation. (C) 2016 The Authors. Published by Elsevier B.V.

Lorentz violation and Faddeev-Popov ghosts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altschul, B.

2006-02-15

We consider how Lorentz-violating interactions in the Faddeev-Popov ghost sector will affect scalar QED. The behavior depends sensitively on whether the gauge symmetry is spontaneously broken. If the symmetry is not broken, Lorentz violations in the ghost sector are unphysical, but if there is spontaneous breaking, radiative corrections will induce Lorentz-violating and gauge-dependent terms in other sectors of the theory.

Direct terrestrial test of Lorentz symmetry in electrodynamics to 10-18

NASA Astrophysics Data System (ADS)

Nagel, Moritz; Parker, Stephen R.; Kovalchuk, Evgeny V.; Stanwix, Paul L.; Hartnett, John G.; Ivanov, Eugene N.; Peters, Achim; Tobar, Michael E.

2015-09-01

Lorentz symmetry is a foundational property of modern physics, underlying the standard model of particles and general relativity. It is anticipated that these two theories are low-energy approximations of a single theory that is unified and consistent at the Planck scale. Many unifying proposals allow Lorentz symmetry to be broken, with observable effects appearing at Planck-suppressed levels; thus, precision tests of Lorentz invariance are needed to assess and guide theoretical efforts. Here we use ultrastable oscillator frequency sources to perform a modern Michelson-Morley experiment and make the most precise direct terrestrial test to date of Lorentz symmetry for the photon, constraining Lorentz violating orientation-dependent relative frequency changes Δν/ν to 9.2+/-10.7 × 10-19 (95% confidence interval). This order of magnitude improvement over previous Michelson-Morley experiments allows us to set comprehensive simultaneous bounds on nine boost and rotation anisotropies of the speed of light, finding no significant violations of Lorentz symmetry.

Identification of GRB2 and GAB1 Coexpression as an Unfavorable Prognostic Factor for Hepatocellular Carcinoma by a Combination of Expression Profile and Network Analysis

PubMed Central

Yang, Mei; Wang, Danhua; Yu, Lingxiang; Guo, Chaonan; Guo, Xiaodong; Lin, Na

2013-01-01

Aim To screen novel markers for hepatocellular carcinoma (HCC) by a combination of expression profile, interaction network analysis and clinical validation. Methods HCC significant molecules which are differentially expressed or had genetic variations in HCC tissues were obtained from five existing HCC related databases (OncoDB.HCC, HCC.net, dbHCCvar, EHCO and Liverome). Then, the protein-protein interaction (PPI) network of these molecules was constructed. Three topological features of the network ('Degree', 'Betweenness', and 'Closeness') and the k-core algorithm were used to screen candidate HCC markers which play crucial roles in tumorigenesis of HCC. Furthermore, the clinical significance of two candidate HCC markers growth factor receptor-bound 2 (GRB2) and GRB2-associated-binding protein 1 (GAB1) was validated. Results In total, 6179 HCC significant genes and 977 HCC significant proteins were collected from existing HCC related databases. After network analysis, 331 candidate HCC markers were identified. Especially, GAB1 has the highest k-coreness suggesting its central localization in HCC related network, and the interaction between GRB2 and GAB1 has the largest edge-betweenness implying it may be biologically important to the function of HCC related network. As the results of clinical validation, the expression levels of both GRB2 and GAB1 proteins were significantly higher in HCC tissues than those in their adjacent nonneoplastic tissues. More importantly, the combined GRB2 and GAB1 protein expression was significantly associated with aggressive tumor progression and poor prognosis in patients with HCC. Conclusion This study provided an integrative analysis by combining expression profile and interaction network analysis to identify a list of biologically significant HCC related markers and pathways. Further experimental validation indicated that the aberrant expression of GRB2 and GAB1 proteins may be strongly related to tumor progression and prognosis in patients with HCC. The overexpression of GRB2 in combination with upregulation of GAB1 may be an unfavorable prognostic factor for HCC. PMID:24391994

Chandra Observations of the X-Ray Environs of SN 1998BW / GRB 980425

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kouveliotou , C.

2004-07-14

We report X-ray studies of the environs of SN 1998bw and GRB 980425 using the Chandra X-Ray Observatory 1281 days after the GRB. Eight X-ray point sources were localized, three and .ve each in the original error boxes--S1 and S2--assigned for variable X-ray counterparts to the GRB by BeppoSAX. The sum of the discrete X-ray sources plus continuous emission in S2 observed by CXO on day 1281 is within a factor of 1.5 of the maximum and the upper limits seen by BeppoSAX. We conclude that S2 is the sum of several variable sources that have not disappeared, and thereforemore » is not associated with the GRB. Within S1, clear evidence is seen for a decline of approximately a factor of 12 between day 200 and day 1281. One of the sources in S1, S1a, is coincident with the well-determined radio location of SN 1998bw, and is certainly the remnant of that explosion. The nature of the other sources is also discussed. Combining our observation of the supernova with others of the GRB afterglow, a smooth X-ray light curve, spanning {approx} 1300 days, is obtained by assuming the burst and supernova were coincident at 35.6 Mpc. When this X-ray light curve is compared with those of the X-ray ''afterglows'' of ordinary GRBs, X-ray Flashes, and ordinary supernovae, evidence emerges for at least two classes of lightcurves, perhaps bounding a continuum. By three to ten years, all these phenomena seem to converge on a common X-ray luminosity, possibly indicative of the supernova underlying them all. This convergence strengthens the conclusion that SN 1998bw and GRB 980425 took place in the same object. One possible explanation for the two classes is a (nearly) standard GRB observed at different angles, in which case X-ray afterglows with intermediate luminosities should eventually be discovered. Finally, we comment on the contribution of GRBs to the ULX source population.« less

Overview of the SVOM Gamma-Ray Burst mission under development with a focus on its Trigger system

NASA Astrophysics Data System (ADS)

Schanne, Stephane

2017-08-01

The SVOM mission (Space-based Variable Objects Monitor) is a Chinese-French satellite mission under development, devoted to collecting a complete sample of Gamma-Ray Bursts (GRBs) observed at multi-wavelengths with a high fraction of redshift determinations. In January 2017 the mission entered Phase C, starting officially construction, and the launch is foreseen in 2021. The SVOM satellite is equipped with 4 instruments, 2 of which cover the prompt GRB phase. The ECLAIRs coded-mask imager surveys a 2-sr large portion of the sky in the 4-150 keV energy range, well suited for the detection of X-ray rich and highly redshifted GRBs. The ECLAIRs trigger system continuously searches for GRBs using two algorithms, a count-rate trigger for short time scales and an image trigger for long time scales. In case of a localized new GRB candidate or a bright outburst of a known source, it promptly requests a satellite slew and sends an alert to ground. The onboard GRM (Gamma-Ray Monitor) extends the prompt energy coverage up to 5 MeV. After slew, 2 more onboard instruments study the GRB afterglow and refine the GRB localization: the MXT (Multi-pore optics X-ray Telescope) and the VT (Visible Telescope). Two types of ground telescopes are dedicated to SVOM. The GFTs (Ground Follow-up Telescopes) repoint autonomously to GRB alerts, refine their localization and provide photometric redshift. The SVOM observing strategy with roughly antisolar pointing combined with Galactic plane avoidance, ensures that most GRBs are quickly visible by the GFTs and large spectroscopic telescopes. The GWAC (Ground Wide Angle Camera) will observe the sky simultaneously with ECLAIRs to detect prompt optical GRB emissions. Today part of the GWAC is already operational. The SVOM GRB program is complemented by pre-planned target observations and ground-commanded targets of opportunity, e.g. to search for electromagnetic counterparts of gravity-wave events. On behalf of the SVOM and ECLAIRs teams, this paper presents an overview of SVOM with a focus on its GRB trigger system.

Pi of the Sky observation of GRB160625B

NASA Astrophysics Data System (ADS)

Opiela, Rafał; Batsch, Tadeusz; Castro-Tirado, Alberto Javier; Czyrkowski, Henryk; Ćwiek, Arkadiusz; Ćwiok, Mikołaj; DÄ browski, Ryszard; Jelinek, Martin; Kasprowicz, Grzegorz; Majcher, Ariel; Małek, Katarzyna; Mankiewicz, Lech; Nawrocki, Krzysztof; Obara, Łukasz; Piotrowski, Lech; Siudek, Małgorzata; Sokołowski, Marcin; Wawrzaszek, Roman; Wrochna, Grzegorz; Zaremba, Marcin; Żarnecki, Aleksander Filip

2017-08-01

Pi of the Sky is a system of wide field of view robotic telescopes, which search for short timescale astrophysical phenomena, especially for prompt optical GRB emission. The system was designed for autonomous operation, monitoring a large fraction of the sky to a depth of 12m-13m and with time resolution of the order of 10 seconds. Custom designed CCD cameras are equipped with Canon lenses f = 85 mm, f/d = 1.2 and cover 20° × 20° of the sky each. The final system with 16 cameras on 4 equatorial mounts was completed in 2014 at the INTA El Arenosillo Test Centre in Spain. GRB160625B was an extremely bright GRB with three distinct emission episodes. Cameras of the Pi of the Sky observatory in Spain were not observing the position of the GRB160625B prior to the first emission episode. Observations started only after receiving Fermi/GBM trigger, about 140 seconds prior to the second emission. As the position estimate taken from the Fermi alert and used to position the telescope was not very accurate, the actual position of the burst happened to be in the overlap region of two cameras, resulting in two independent sets of measurements. Light curves from both cameras were reconstructed using the Luiza framework. No object brighter than 12.4m (3σ limit) was observed prior to the second GRB emission. An optical flash was identified on an image starting -5.9s before the time of the Fermi/LAT trigger, brightening to about 8m on the next image and then becoming gradually dimmer, fading below our sensitivity after about 400s. Emission features as measured in different spectral bands indicate that the three emission episodes of GRB160625B were dominated by distinct physics process. Simultaneously observations in gamma-rays and optical wavelengths support the hypothesis that this was the first observed transition from thermal to non-thermal radiation in a single GRB. Main results of the combined analysis are presented.

Gamma-Ray Bursts: Lighting Up the High-Redshift Universe

NASA Astrophysics Data System (ADS)

Toy, Vicki Louise

Gamma-ray bursts (GRBs) are the most luminous events in the Universe with Egamma,iso ˜ 1048-54 erg. Leading models hypothesize that GRBs are created from inter- nal collisions within collimated and ultrarelativistic jets. The jets then shock-heat the surrounding material (e.g. interstellar medium) to create GRB afterglows. These afterglows are extremely useful probes of the Universe because long GRBs are (1) bright events that can be used as backlights for absorption studies, (2) able to probe at all redshifts massive stars exist, and (3) transient events that allow us to follow- up on the host galaxies at late times. In this thesis we study the environments of GRBs. We first explore the relationship between GRB and supernova (SN) using a nearby GRB-SN (GRB 130702A/SN 2013dx) at z = 0.145. There are only nine other GRB-SNe that were close enough to have extensive spectroscopic and photometric follow-up of the SN at late times. We create a quasi-bolometic light curve of SN 2013dx and fit an analytical equation to the quasi-bolometric light curve combined with measurements of the photospheric velocity to determine SN parameters: mass of 56Ni, kinetic energy, and ejecta mass. We examine the relationship between SN parameters and E gamma,iso for the 10 well-studied GRB-SNe, but find no correlations despite numerical simulation predictions that the mass of 56Ni should correlate with the degree of asymmetry. We then move to larger distance scales and use GRB afterglows as bright back- lights to study distant galaxies. We examine the galactic environments of Damped Lyman-alpha systems (DLAs; NHI ≥ 1020.3 cm-2 ) identified with GRB afterglows at z ˜ 2 - 6. We use late-time photometry after the GRB afterglow has faded to determine star formation rates (SFRs) from rest-frame ultraviolet measurements or spectral energy distribution (SED) models from multiband photometry. We com- pare our sample's SFRs to a sample of quasars (QSOs) DLA host galaxies. Despite the overlapping NHI and redshift ranges, our GRB-DLA galaxies have much larger SFRs than the QSO-DLA host galaxy sample; this may suggest that the QSO-DLA and GRB-DLA galaxy populations are different. We also compare star formation efficiencies to the local Universe and simulations at z = 3. A large portion of this thesis has focused on the development of a new ground- based GRB afterglow follow-up instrument, the Rapid infrared IMAger-Spectrometer (RIMAS), that will target high-redshift GRB afterglows to study early galaxy envi- ronments. RIMAS covers 0.97-2.37 mum and can simultaneously observe two band-passes in any observing mode: photometry, low-resolution spectroscopy (R ˜ 30), or high-resolution spectroscopy (R ˜ 4000). In particular, this thesis focuses on RIMAS's three detectors: two science grade Teledyne HgCdTe Astronomy Wide Area Infrared Imager with 2K x 2K, Reference Pixels and Guide Mode (H2RG) and a slit-viewer Spitzer Legacy Indium-Antimonide (InSb) array. We describe the detector hardware and characterization in detail and discuss general infrared detector troubleshooting methods at both cryogenic and room temperatures. Several software packages have been developed for RIMAS throughout this thesis work. We introduce RIMAS's quick reduction pipeline that takes raw images from a single acquisition and returns a single result frame. We then present a generalized data reduction pipeline that we have tested on two currently operational photometers. We also describe our detailed and realistic RIMAS throughput models for all three observing modes as well as our online observer calculators with these throughput models. All of our data products are open source and are publicly available on Github repositories with detailed documentation.

Average intensity and coherence properties of a partially coherent Lorentz-Gauss beam propagating through oceanic turbulence

NASA Astrophysics Data System (ADS)

Liu, Dajun; Wang, Guiqiu; Wang, Yaochuan

2018-01-01

Based on the Huygens-Fresnel integral and the relationship of Lorentz distribution and Hermite-Gauss function, the average intensity and coherence properties of a partially coherent Lorentz-Gauss beam propagating through oceanic turbulence have been investigated by using numerical examples. The influences of beam parameters and oceanic turbulence on the propagation properties are also discussed in details. It is shown that the partially coherent Lorentz-Gauss beam with smaller coherence length will spread faster in oceanic turbulence, and the stronger oceanic turbulence will accelerate the spreading of partially coherent Lorentz-Gauss beam in oceanic turbulence.

The Fast Evolution of SN 2010bh Associated with XRF 100316D

NASA Technical Reports Server (NTRS)

Olivares E., F.; Greiner, J.; Schady, P.; Rau, A.; Klose, S.; Kruhler, T.; Afonso, P. M. J.; Updike, A. C.; Nardini, M.; Filgas, R.;

Thomas precession, Wigner rotations and gauge transformations

NASA Technical Reports Server (NTRS)

Han, D.; Kim, Y. S.; Son, D.

1987-01-01

The exact Lorentz kinematics of the Thomas precession is discussed in terms of Wigner's O(3)-like little group which describes rotations in the Lorentz frame in which the particle is at rest. A Lorentz-covariant form for the Thomas factor is derived. It is shown that this factor is a Lorentz-boosted rotation matrix, which becomes a gauge transformation in the infinite-momentum or zero-mass limit.

First measurement of H I 21 cm emission from a GRB host galaxy indicates a post-merger system

NASA Astrophysics Data System (ADS)

Arabsalmani, Maryam; Roychowdhury, Sambit; Zwaan, Martin A.; Kanekar, Nissim; Michałowski, Michał J.

2015-11-01

We report the detection and mapping of atomic hydrogen in H I 21 cm emission from ESO 184-G82, the host galaxy of the gamma-ray burst 980425. This is the first instance where H I in emission has been detected from a galaxy hosting a gamma-ray burst (GRB). ESO 184-G82 is an isolated galaxy and contains a Wolf-Rayet region close to the location of the GRB and the associated supernova, SN 1998bw. This is one of the most luminous H II regions identified in the local Universe, with a very high inferred density of star formation. The H I 21 cm observations reveal a high H I mass for the galaxy, twice as large as the stellar mass. The spatial and velocity distribution of the H I 21 cm emission reveals a disturbed rotating gas disc, which suggests that the galaxy has undergone a recent minor merger that disrupted its rotation. We find that the Wolf-Rayet region and the GRB are both located in the highest H I column density region of the galaxy. We speculate that the merger event has resulted in shock compression of the gas, triggering extreme star formation activity, and resulting in the formation of both the Wolf-Rayet region and the GRB. The high H I column density environment of the GRB is consistent with the high H I column densities seen in absorption in the host galaxies of high-redshift GRBs.

HAPPY BIRTHDAY SWIFT: ULTRA-LONG GRB 141121A AND ITS BROADBAND AFTERGLOW

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cucchiara, A.; Veres, P.; Corsi, A.

2015-10-20

We present our extensive observational campaign on the Swift-discovered GRB 141121A, almost 10 years after its launch. Our observations cover radio through X-rays and extend for more than 30 days after discovery. The prompt phase of GRB 141121A lasted 1410 s and, at the derived redshift of z = 1.469, the isotropic energy is E{sub γ,iso} = 8.0 × 10{sup 52} erg. Due to the long prompt duration, GRB 141121A falls into the recently discovered class of ultra-long GRBs (UL-GRBs). Peculiar features of this burst are (1) a flat early-time optical light curve and (2) a radio-to-X-ray rebrightening around threemore » days after the burst. The latter is followed by a steep optical-to-X-ray decay and a much shallower radio fading. We analyze GRB 141121A in the context of the standard forward–reverse shock (FS, RS) scenario and we disentangle the FS and RS contributions. Finally, we comment on the puzzling early-time (t ≲ 3 days) behavior of GRB 141121A, and suggest that its interpretation may require a two-component jet model. Overall, our analysis confirms that the class of UL-GRBs represents our best opportunity to firmly establish the prominent emission mechanisms in action during powerful gamma-ray burst explosions, and future missions (like SVOM, XTiDE, or ISS-Lobster) will provide many more of such objects.« less

The GW170817/GRB 170817A/AT 2017gfo Association: Some Implications for Physics and Astrophysics

NASA Astrophysics Data System (ADS)

Wang, Hao; Zhang, Fu-Wen; Wang, Yuan-Zhu; Shen, Zhao-Qiang; Liang, Yun-Feng; Li, Xiang; Liao, Neng-Hui; Jin, Zhi-Ping; Yuan, Qiang; Zou, Yuan-Chuan; Fan, Yi-Zhong; Wei, Da-Ming

2017-12-01

On 2017 August 17, a gravitational-wave event (GW170817) and an associated short gamma-ray burst (GRB 170817A) from a binary neutron star merger had been detected. The follow-up optical/infrared observations also identified the macronova/kilonova emission (AT 2017gfo). In this work, we discuss some implications of the remarkable GW170817/GRB 170817A/AT 2017gfo association. We show that the ∼1.7 s time delay between the gravitational-wave (GW) and GRB signals imposes very tight constraints on the superluminal movement of gravitational waves (i.e., the relative departure of GW velocity from the speed of light is ≤slant 4.3× {10}-16) or the possible violation of the weak equivalence principle (i.e., the difference of the gamma-ray and GW trajectories in the gravitational field of the galaxy and the local universe should be within a factor of ∼ 3.4× {10}-9). The so-called Dark Matter Emulators and a class of contender models for cosmic acceleration (“Covariant Galileon”) are ruled out as well. The successful identification of lanthanide elements in the macronova/kilonova spectrum also excludes the possibility that the progenitors of GRB 170817A are a binary strange star system. The high neutron star merger rate (inferred from both the local sGRB data and the gravitational-wave data) together with the significant ejected mass strongly suggest that such mergers are the prime sites of heavy r-process nucleosynthesis.

GRB 110715A: the peculiar multiwavelength evolution of the first afterglow detected by ALMA

NASA Astrophysics Data System (ADS)

Sánchez-Ramírez, R.; Hancock, P. J.; Jóhannesson, G.; Murphy, Tara; de Ugarte Postigo, A.; Gorosabel, J.; Kann, D. A.; Krühler, T.; Oates, S. R.; Japelj, J.; Thöne, C. C.; Lundgren, A.; Perley, D. A.; Malesani, D.; de Gregorio Monsalvo, I.; Castro-Tirado, A. J.; D'Elia, V.; Fynbo, J. P. U.; Garcia-Appadoo, D.; Goldoni, P.; Greiner, J.; Hu, Y.-D.; Jelínek, M.; Jeong, S.; Kamble, A.; Klose, S.; Kuin, N. P. M.; Llorente, A.; Martín, S.; Nicuesa Guelbenzu, A.; Rossi, A.; Schady, P.; Sparre, M.; Sudilovsky, V.; Tello, J. C.; Updike, A.; Wiersema, K.; Zhang, B.-B.

2017-02-01

We present the extensive follow-up campaign on the afterglow of GRB 110715A at 17 different wavelengths, from X-ray to radio bands, starting 81 s after the burst and extending up to 74 d later. We performed for the first time a GRB afterglow observation with the ALMA observatory. We find that the afterglow of GRB 110715A is very bright at optical and radio wavelengths. We use the optical and near-infrared spectroscopy to provide further information about the progenitor's environment and its host galaxy. The spectrum shows weak absorption features at a redshift z = 0.8225, which reveal a host-galaxy environment with low ionization, column density, and dynamical activity. Late deep imaging shows a very faint galaxy, consistent with the spectroscopic results. The broad-band afterglow emission is modelled with synchrotron radiation using a numerical algorithm and we determine the best-fitting parameters using Bayesian inference in order to constrain the physical parameters of the jet and the medium in which the relativistic shock propagates. We fitted our data with a variety of models, including different density profiles and energy injections. Although the general behaviour can be roughly described by these models, none of them are able to fully explain all data points simultaneously. GRB 110715A shows the complexity of reproducing extensive multiwavelength broad-band afterglow observations, and the need of good sampling in wavelength and time and more complex models to accurately constrain the physics of GRB afterglows.

Possible correlations between gamma-ray burst and its host galaxy offset

NASA Astrophysics Data System (ADS)

Wang, Fei-Fei; Zou, Yuan-Chuan; Liu, Yu; Liao, Bin; Moharana, Reetanjali

2018-06-01

We collected the information of 304 gamma-ray bursts (GRBs) from the literature, and analyzed the correlations among the host galaxy offsets (the distance from the site of the GRB to the center of its host galaxy), T90,i (the duration T90 in rest-frame), TR45,i (the duration TR45 in rest-frame), Eγ,iso (the isotropic equivalent energy), Lγ,iso (=Eγ,iso /T90,i, the isotropic equivalent luminosity) and Lpk (peak luminosity). We found that T90,i, TR45,i, Eγ,iso, Lpk have negative correlation with offset, which is consistent with origin of short GRBs (SGRBs) and long GRBs (LGRBs). On separate analysis, we found similar results for log ⁡Eγ,iso - log ⁡ (offset) and log ⁡Lpk - log ⁡ (offset) relations in case of SGRBs only, while no obvious relation for LGRBs. There is no correlations between offset and Lγ,iso. We also put the special GRB 170817A and GRB 060218A on the plots. The two GRBs both have low luminosity and small offset. In the log ⁡ (offset) - log ⁡T90,i plot, we found GRB 170817A locates in between the two regions of SGRBs and LGRBs and it is the outlier in the offset -Eγ,iso, offset -Lγ,iso and offset -Lpk plots. Together with GRB 060218A being an outlier in all plots, it indicates the speciality of GRBs 170817A and 060218A, and might imply more subgroups of the GRB samples.

Studies of Gamma-Ray Burst Prompt Emission with RHESSI and NCT

NASA Astrophysics Data System (ADS)

Bellm, Eric Christopher

Gamma-Ray Bursts (GRBs) are the most luminous objects in the universe. They herald a catastrophic energy release which manifests itself in tenths to hundreds of seconds of irregular gamma-ray emission. This initial "prompt" emission is followed by "afterglow" emission at other wavelengths that fades smoothly over hours to years. GRB prompt emission has been observed with ever-increasing sophistication for more than four decades, but many details of its origin remain unknown. While GRBs are under-stood to result from relativistic jets produced by violent reconfigurations of compact objects, the composition of the outflow, the means of energy dissipation, and the radiative processes underlying the observed emission are all uncertain. I review the present understanding of all facets of GRB science in Chapter 1. Gamma-ray spectroscopy and polarimetry provide two channels for testing models of GRB prompt emission with observed data. In Chapters 2--4, I employ the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) to conduct broad-band time-resolved spectroscopy of bright GRBs. RHESSI is a solar observatory that uses nine coaxial germanium detectors for imaging and spectroscopy of solar flares. Because the detectors are unshielded, RHESSI also records counts from off-axis sources like GRBs. In Chapter 2, I detail the methods I use for analyzing RHESSI GRB data. In Chapter 3, I conduct joint spectral analysis of bursts co-observed by RHESSI and Swift-BAT, enabling spectral modeling over a wide 15 keV--17 MeV band. These results reveal the difficulty of predicting the peak spectral energy of a burst from BAT observations alone. While GRB spectra commonly have been assumed to be non-thermal and have been fit by purely phenomenological models, some authors have proposed that thermal emission from the GRB photosphere may be the source of the GRB spectral peak. In Chapter 4, I perform time-resolved spectroscopy of bright GRBs observed by RHESSI and compare the fit results of several phenomenological and quasi-thermal models. The fit results for the quasi-thermal models are poorer than those reported for fits in more narrow energy bands, and the fit parameters show significant dependence on the fit band. More sophisticated models and additional data are needed to determine the relevance of the photospheric emission. Polarimetric studies of GRBs are in their infancy, but they have the potential to distinguish GRB emission models and probe the structure of the relativistic jet. Observations to date have exploited the polarimetric signatures produced by Compton scattering in gamma-ray observatories. Since these instruments have poor spatial resolution and are not calibrated for polarimetric observations, only a few bright GRBs have been observed, each with significant systematic effects. In Chapters 5--8, I present development work for a balloon-borne Compton telescope, the Nuclear Compton Telescope (NCT), which is capable of measuring GRB polarization. NCT uses planar cross-strip germanium detectors for Compton imaging (200 keV--10 MeV) and polarimetry (200 keV--2 MeV). Chapter 5 describes NCT and its flight history. In Chapter 6, I discuss calibrations of the effective area of NCT during the 2009 New Mexico and 2010 Australia balloon campaigns. By placing radioactive sources of known activity throughout the NCT field of view, it is possible to determine the efficiency of the telescope. I compare these values to those derived from detailed Monte Carlo simulations. The values derived from the real data show a roughly constant deficit relative to those derived from the Monte Carlo simulations which may be related to known deficiencies in the lower-level event calibrations. Chapter 7 assesses NCT's polarimetric performance. I generated partially polarized beams throughout NCT's field of view by scattering photons off of a scintillator slab triggered in coincidence with the NCT detectors. The measured polarimetric modulation showed good agreement with Monte Carlo simulations for some calibrations, although systematic geometric effects are present. NCT's polarimetric performance compares well to that of other Compton telescopes. Finally, in Chapter 8 I calculate NCT's sensitivity to GRBs and expected detection rate. Using single-site and incompletely-absorbed events, NCT has about one-fourth the sensitivity of BATSE LAD. NCT could detect about half of the bursts in the BATSE catalog if they occurred in its field of view. Bursts bright enough for polarimetric analysis are too rare to detect effectively from a balloon platform, however, so a satellite instrument with NCT-like detectors would be needed to perform a useful census of GRB polarization. Better understanding of the GRB prompt emission will clarify the place of GRBs in stellar life cycles, provide new insights into the physics of collisionless shocks and relativistic jets, and facilitate the use of GRBs as probes of the early universe and electromagnetic counterparts to gravitational wave and neutrino signals. The complex phenomenology of GRBs creates both a challenge and a rich opportunity to explain and utilize these enigmatic events.

Gamma-ray Burst Cosmology

NASA Astrophysics Data System (ADS)

Wang, F. Y.

2011-07-01

Gamma-ray bursts (GRBs) are brief flashes of gamma-rays occurring at cosmological distances. GRB was discovered by Vela satellite in 1967. The discovery of afterglows in 1997 made it possible to measure the GRBs' redshifts and confirmed the cosmological origin. GRB cosmology includes utilizing long GRBs as standard candles to constrain the dark energy and cosmological parameters, measuring the high-redshift star formation rate (SFR), probing the metal enrichment history of the universe, dust, quantum gravity, etc. The correlations between GRB observables in the prompt emission and afterglow phases were discovered, so we can use these correlations as standard candles to constrain the cosmological parameters and dark energy, especially at high redshifts. Observations show that long GRBs may be associated with supernovae. So long GRBs are promising tools to measure the high-redshift SFR. GRB afterglows have a smooth continuum, so the extraction of IGM absorption features from the spectrum is very easy. The information of metal enrichment history and reionization can be obtained from the absorption lines. In this thesis, we investigate the high-redshift cosmology using GRBs, called GRB cosmology. This is a new and fast developing field. The structure of this thesis is as follows. In the first chapter, we introduce the progress of GRB studies. First we introduce the progress of GRB studies in various satellite eras, mainly in the Swift and Fermi eras. The fireball model and standard afterglow model are also presented. In chapter 2, we introduce the standard cosmology model, astronomical observations and dark energy models. Then progress on the GRB cosmology studies is introduced. Some of my works including what to be submitted are also introduced in this chapter. In chapter 3, we present our studies on constraining the cosmological parameters and dark energy using latest observations. We use SNe Ia, GRBs, CMB, BAO, the X-ray gas mass fraction in clusters and the linear growth rate of perturbations, and find that the ΛCDM is the best fitted model. The transition redshift z_{T} is from 0.40_{-0.08}^{+0.14} to 0.65_{-0.05}^{+0.10}. This is the first time to combine GRBs with other observations to constrain the cosmological parameters, dark energy and transition redshift. In chapter 4, we investigate the early dark energy model using GRBs, SNe Ia, CMB and BAO. The negligible dark energy at high redshift will influence the growth of cosmic structures and leave observable signatures that are different from the standard cosmology. We propose that GRBs are promising tools to study the early dark energy. We find that the fractional dark energy density is less than 0.03 and the linear growth index of perturbations is 0.66. In chapter 5, we use a model-independent method to constrain the dark energy equation of state (EOS) w(z). Among the parameters describing the properties of dark energy, EOS is the most important. Whether and how it evolves with time are crucial in distinguishing different cosmological models. In our analysis, we include high-redshift GRBs. We find that w(z)<0 at z>1.7, and EOS deviates from the cosmological constant at z>0.5 at 95.4% confidence level. In chapter 6, we probe the cosmographic parameters to distinguish between the dark energy and modified gravity models. These two families of models can drive the universe to acclerate. We first derive the expressions of deceleration, jerk and snap parameters in the dark energy and modified gravity models. The snap parameters in these models are different, so they can be used to distinguish between the models. In chapter 7, we measure the high-redshift SFR using long GRBs. Swift observations reveal that the number of high-redshift GRBs is larger than the predication from SFR. We find that the evolving initial mass function can interpret this discrepancy. We study the high-redshift SFR up to z˜ 8.2 considering the Swift GRBs tracing the star formation history and the cosmic metallicity evolution in different background cosmological models. In chapter 8, we present the observational signatures of Pop III GRBs and study the pre-galactic metal enrichment with the metal absorption lines in the GRB spectrum from first galaxy. We focus on the unusual circumburst environment inside the systems that hosted Pop III stars. The metals in the first galaxies produced by the first supernova explosion are likely to reside in the low-ionization states (C II, O I, Si II and Fe II). When GRB afterglow goes through the metal polluted region, the metal absorption lines may appear. The topology of metal enrichment could be highly inhomogeneous, so along different lines of sight, the metal absorption lines may show distinct signatures. A summary of the open questions in GRB cosmology filed is presented in chapter 9.

The Second Swift BAT Gamma-Ray Burst Catalog

NASA Technical Reports Server (NTRS)

Barthelmy, S. D.; Baumgartner, W. H.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.; Sato, G.;

New 40Ar/ 39Ar dating of the Grande Ronde lavas, Columbia River Basalts, USA: Implications for duration of flood basalt eruption episodes

NASA Astrophysics Data System (ADS)

Barry, T. L.; Self, S.; Kelley, S. P.; Reidel, S.; Hooper, P.; Widdowson, M.

2010-08-01

Grande Ronde Basalt (GRB) lavas represent the most voluminous eruptive pulse of the Columbia River-Snake River-Yellowstone hotspot volcanism. With an estimated eruptive volume of 150,000 km 3, GRB lavas form at least 66% of the total volume of the Columbia River Basalt Group. New 40Ar/ 39Ar dates for GRB lavas reveal they were emplaced within a maximum period of 0.42 ± 0.18 My. A well-documented stratigraphy indicates at least 110 GRB flow fields (or individual eruptions), and on this basis suggests an average inter-eruption hiatus of less than 4000 years. Isotopic age-dating cannot resolve time gaps between GRB eruptions, and it is difficult to otherwise form a picture of the durations of eruptions because of non-uniform weathering in the top of flow fields and a general paucity of sediments between GR lavas. Where sediment has formed on top of GRB lavas, it varies in thickness from zero to 20-30 cm of silty to fine-sandy material, with occasional diatomaceous sediment. Individual GRB eruptions varied considerably in volume but many were greater than 1000 km 3 in size. Most probably eruptive events were not equally spaced in time; some eruptions may have followed short periods of volcanic repose (perhaps 10 2 to 10 3 of years), whilst others could have been considerably longer (many 1000 s to > 10 4 years). Recent improvements in age-dating for other continental flood basalt (CFB) lava sequences have yielded estimates of total eruptive durations of less than 1 My for high-volume pulses of lava production. The GRB appears to be a similar example, where the main pulse occupied a brief period. Even allowing for moderate to long-duration pahoehoe flow field production, the amount of time the system spends in active lava-producing mode is small — less than c. 2.6% (based on eruption durations of approximately 10,000 years, compared to the duration of the entire eruptive pulse of c. 420,000 years). A review of available 40Ar/ 39Ar data for the major voluminous phases of the Columbia River Basalt Group suggests that activity of the Steens Basalt-Imnaha Basalt-GRB may have, at times, been simultaneous, with obvious implications for climatic effects. Resolving intervals between successive eruptions during CFB province construction, and durations of main eruptive pulses, remains vital to determining the environmental impact of these huge eruptions.

Propagation of a radial phased-locked Lorentz beam array in turbulent atmosphere.

PubMed

Zhou, Guoquan

2011-11-21

A radial phased-locked (PL) Lorentz beam array provides an appropriate theoretical model to describe a coherent diode laser array, which is an efficient radiation source for high-power beaming use. The propagation of a radial PL Lorentz beam array in turbulent atmosphere is investigated. Based on the extended Huygens-Fresnel integral and some mathematical techniques, analytical formulae for the average intensity and the effective beam size of a radial PL Lorentz beam array are derived in turbulent atmosphere. The average intensity distribution and the spreading properties of a radial PL Lorentz beam array in turbulent atmosphere are numerically calculated. The influences of the beam parameters and the structure constant of the atmospheric turbulence on the propagation of a radial PL Lorentz beam array in turbulent atmosphere are discussed in detail. © 2011 Optical Society of America

Lorentz quantum mechanics

NASA Astrophysics Data System (ADS)

Zhang, Qi; Wu, Biao

2018-01-01

We present a theoretical framework for the dynamics of bosonic Bogoliubov quasiparticles. We call it Lorentz quantum mechanics because the dynamics is a continuous complex Lorentz transformation in complex Minkowski space. In contrast, in usual quantum mechanics, the dynamics is the unitary transformation in Hilbert space. In our Lorentz quantum mechanics, three types of state exist: space-like, light-like and time-like. Fundamental aspects are explored in parallel to the usual quantum mechanics, such as a matrix form of a Lorentz transformation, and the construction of Pauli-like matrices for spinors. We also investigate the adiabatic evolution in these mechanics, as well as the associated Berry curvature and Chern number. Three typical physical systems, where bosonic Bogoliubov quasi-particles and their Lorentz quantum dynamics can arise, are presented. They are a one-dimensional fermion gas, Bose-Einstein condensate (or superfluid), and one-dimensional antiferromagnet.

Lorentz violation, gravitoelectromagnetism and Bhabha scattering at finite temperature

NASA Astrophysics Data System (ADS)

Santos, A. F.; Khanna, Faqir C.

2018-04-01

Gravitoelectromagnetism (GEM) is an approach for the gravitation field that is described using the formulation and terminology similar to that of electromagnetism. The Lorentz violation is considered in the formulation of GEM that is covariant in its form. In practice, such a small violation of the Lorentz symmetry may be expected in a unified theory at very high energy. In this paper, a non-minimal coupling term, which exhibits Lorentz violation, is added as a new term in the covariant form. The differential cross-section for Bhabha scattering in the GEM framework at finite temperature is calculated that includes Lorentz violation. The Thermo Field Dynamics (TFD) formalism is used to calculate the total differential cross-section at finite temperature. The contribution due to Lorentz violation is isolated from the total cross-section. It is found to be small in magnitude.

Lorentz and CPT Tests with Atoms

NASA Astrophysics Data System (ADS)

Vargas Silva, Arnaldo J.

The prospects for using atomic-spectroscopy experiments to test Lorentz and CPT symmetry are investigated. Phenomenological models for Lorentz violation studied in this work include ones with contributions from all quadratic operators for a Dirac fermion in the Lagrange density of the Standard-Model Extension (SME), without restriction on the operator mass dimension. The systems considered include atoms composed of conventional matter, antimatter, and second-generation particles. Generic expressions for the Lorentz-violating energy shifts applicable to a broad range of atomic transitions are obtained. Signals for Lorentz violation that can in principle be studied in spectroscopic experiments are identified from the theoretical corrections to the spectrum. Some of these signals include sidereal and annual variations of atomic transition frequencies measured in a laboratory on the surface of the Earth. Other possibilities include effects produced by changing the orientation of the applied magnetic field or by realizing space-based experiments. Discrepancies in the experimental values for fundamental constants and energy levels based on self-consistent predictions from the Standard Model also offer potential signals for Lorentz violation. The sensitivities of different experiments to distinct sets of coefficients for Lorentz violation are considered. Using atoms composed of different particle species allows measurements of coefficients for Lorentz violation in different fermion sectors of the SME. Experiments comparing hydrogen and antihydrogen can discriminate between coefficients for Lorentz violation that are associated with CPT-odd or CPT-even operators. Additionally, certain systems and transitions are more sensitive to nonminimal operators, while others are particularly sensitive to minimal ones.

Wind-Interaction Models for the Early Afterglows of Gamma-Ray Bursts: The Case of GRB 021004

NASA Astrophysics Data System (ADS)

Li, Zhi-Yun; Chevalier, Roger A.

2003-06-01

Wind-interaction models for gamma-ray burst (GRB) afterglows predict that the optical emission from the reverse shock drops below that from the forward shock within hundreds of seconds of the burst. The typical frequency νm of the synchrotron emission from the forward shock passes through the optical band typically on a timescale of minutes to hours. Before the passage of νm, the optical flux evolves as t-1/4, and after the passage, the decay steepens to t-(3p-2)/4, where p is the exponent for the assumed power-law energy distribution of nonthermal electrons and is typically ~2. The steepening in the slope of temporal decay should be readily identifiable in the early afterglow light curves. We propose that such a steepening was observed in the R-band light curve of GRB 021004 around day 0.1. Available data at several radio frequencies are consistent with this interpretation, as are the X-ray observations around day 1. The early evolution of GRB 021004 contrasts with that of GRB 990123, which can be described by emission from interaction with a constant density medium.

Photospheric Emission in the Joint GBM and Konus Prompt Spectra of GRB 120323A

NASA Technical Reports Server (NTRS)

Guiriec, S.; Gehrels, N.; McEnery, J.; Kouveliotou, C.; Hartmann, D. H.

2017-01-01

GRB 120323A is a very intense short gamma-ray burst (GRB) detected simultaneously during its prompt gamma-ray emission phase with the Gamma-Ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Space Telescope and the Konus experiment on board the Wind satellite. GBM and Konus operate in the kiloelectronvolt - megaelectronvolt regime; however, the GBM range is broader toward both the low and the high parts of the gamma-ray spectrum. Analyses of such bright events provide a unique opportunity to check the consistency of the data analysis as well as cross-calibrate the two instruments. We performed time-integrated and coarse time-resolved spectral analysis of GRB 120323A prompt emission. We conclude that the analyses of GBM and Konus data are only consistent when using a double-hump spectral shape for both data sets; in contrast, the single hump of the empirical Band function, traditionally used to fit GRB prompt emission spectra, leads to significant discrepancies between GBM and Konus analysis results. Our two-hump model is a combination of a thermal-like and a non-thermal component. We interpret the first component as a natural manifestation of the jet photospheric emission.

Long-Duration Gamma-Ray Burst Host Galaxies in Emission and Absorption

NASA Astrophysics Data System (ADS)

Perley, Daniel A.; Niino, Yuu; Tanvir, Nial R.; Vergani, Susanna D.; Fynbo, Johan P. U.

2016-12-01

The galaxy population hosting long-duration GRBs provides a means to constrain the progenitor and an opportunity to use these violent explosions to characterize the nature of the high-redshift universe. Studies of GRB host galaxies in emission reveal a population of star-forming galaxies with great diversity, spanning a wide range of masses, metallicities, and redshifts. However, as a population GRB hosts are significantly less massive and poorer in metals than the hosts of other core-collapse transients, suggesting that GRB production is only efficient at metallicities significantly below Solar. GRBs may also prefer compact galaxies, and dense and/or central regions of galaxies, more than other types of core-collapse explosion. Meanwhile, studies of hosts in absorption against the luminous GRB optical afterglow provide a unique means of unveiling properties of the ISM in even the faintest and most distant galaxies; these observations are helping to constrain the chemical evolution of galaxies and the properties of interstellar dust out to very high redshifts. New ground- and space-based instrumentation, and the accumulation of larger and more carefully-selected samples, are continually enhancing our view of the GRB host population.

TGF-β2 induces Grb2 to recruit PI3-K to TGF-RII that activates JNK/AP-1-signaling and augments invasiveness of Theileria-transformed macrophages

PubMed Central

Haidar, Malak; Whitworth, Jessie; Noé, Gaelle; Liu, Wang Qing; Vidal, Michel; Langsley, Gordon

2015-01-01

Theileria-infected macrophages display many features of cancer cells such as heightened invasive capacity; however, the tumor-like phenotype is reversible by killing the parasite. Moreover, virulent macrophages can be attenuated by multiple in vitro passages and so provide a powerful model to elucidate mechanisms related to transformed macrophage virulence. Here, we demonstrate that in two independent Theileria-transformed macrophage cell lines Grb2 expression is down-regulated concomitant with loss of tumor virulence. Using peptidimer-c to ablate SH2 and SH3 interactions of Grb2 we identify TGF-receptor II and the p85 subunit of PI3-K, as Grb2 partners in virulent macrophages. Ablation of Grb2 interactions reduces PI3-K recruitment to TGF-RII and decreases PIP3 production, and dampens JNK phosphorylation and AP-1-driven transcriptional activity down to levels characteristic of attenuated macrophages. Loss of TGF-R>PI3-K>JNK>AP-1 signaling negatively impacts on virulence traits such as reduced JAM-L/ITG4A and Fos-B/MMP9 expression that contribute to virulent macrophage adhesion and invasiveness. PMID:26511382

UFFO/ Lomonosov: The Payload for the Observation of Early Photons from Gamma Ray Bursts

NASA Astrophysics Data System (ADS)

Park, I. H.; Panasyuk, M. I.; Reglero, V.; Chen, P.; Castro-Tirado, A. J.; Jeong, S.; Bogomolov, V.; Brandt, S.; Budtz-Jørgensen, C.; Chang, S.-H.; Chang, Y. Y.; Chen, C.-R.; Chen, C.-W.; Choi, H. S.; Connell, P.; Eyles, C.; Gaikov, G.; Garipov, G.; Huang, J.-J.; Huang, M.-H. A.; Jeong, H. M.; Kim, J. E.; Kim, M. B.; Kim, S.-W.; Lee, H. K.; Lee, J.; Lim, H.; Lin, C.-Y.; Liu, T.-C.; Nam, J. W.; Petrov, V.; Ripa, J.; Rodrigo, J. M.; Svertilov, S.; Wang, M.-Z.; Yashin, I.

2018-02-01

The payload of the UFFO (Ultra-Fast Flash Observatory)-pathfinder now onboard the Lomonosov spacecraft (hereafter UFFO/ Lomonosov) is a dedicated instrument for the observation of GRBs. Its primary aim is to capture the rise phase of the optical light curve, one of the least known aspects of GRBs. Fast response measurements of the optical emission of GRB will be made by a Slewing Mirror Telescope (SMT), a key instrument of the payload, which will open a new frontier in transient studies by probing the early optical rise of GRBs with a response time in seconds for the first time. The SMT employs a rapidly slewing mirror to redirect the optical axis of the telescope to a GRB position prior determined by the UFFO Burst Alert Telescope (UBAT), the other onboard instrument, for the observation and imaging of X-rays. UFFO/Lomonosov was launched successfully from Vostochny, Russia on April 28, 2016, and will begin GRB observations after completion of functional checks of the Lomonosov spacecraft. The concept of early GRB photon measurements with UFFO was reported in 2012. In this article, we will report in detail the first mission, UFFO/Lomonosov, for the rapid response to GRB observations.

ALMA and RATIR observations of GRB 131030A

NASA Astrophysics Data System (ADS)

Huang, Kuiyun; Urata, Yuji; Takahashi, Satoko; Im, Myungshin; Yu, Po-Chieh; Choi, Changsu; Butler, Nathaniel; Watson, Alan M.; Kutyrev, Alexander; Lee, William H.; Klein, Chris; Fox, Ori D.; Littlejohns, Owen; Cucchiara, Nino; Troja, Eleonora; González, Jesús; Richer, Michael G.; Román-Zúñiga, Carlos; Bloom, Josh; Prochaska, J. Xavier; Gehrels, Neil; Moseley, Harvey; Georgiev, Leonid; de Diego, José A.; Ramirez-Ruiz, Enrico

2017-04-01

We report on the first open-use based Atacama Large Millimeter/submm Array (ALMA) 345 GHz observation for the late afterglow phase of GRB 131030A. The ALMA observation constrained a deep limit at 17.1 d for the afterglow and host galaxy. We also identified a faint submillimeter source (ALMA J2300-0522) near the GRB 131030A position. The deep limit at 345 GHz and multifrequency observations obtained using Swift and RATIR yielded forward-shock modeling with a two-dimensional relativistic hydrodynamic jet simulation and described X-ray excess in the afterglow. The excess was inconsistent with the synchrotron self-inverse Compton radiation from the forward shock. The host galaxy of GRB 131030A and optical counterpart of ALMA J2300-0522 were also identified in the Subaru image. Based on the deep ALMA limit for the host galaxy, the 3σ upper limits of IR luminosity and the star formation rate (SFR) are estimated as LIR < 1.11 × 1011 L⊙ and SFR <18.7 (M⊙ yr-1), respectively. Although the separation angle from the burst location (3{^''.}5) was rather large, ALMA J2300-0522 may be one component of the GRB 131030A host galaxy, according to previous host galaxy cases.

MODELING THE MULTI-BAND AFTERGLOW OF GRB 130831A: EVIDENCE FOR A SPINNING-DOWN MAGNETAR DOMINATED BY GRAVITATIONAL WAVE LOSSES?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Q.; Zong, H. S.; Huang, Y. F., E-mail: zonghs@nju.edu.cn, E-mail: hyf@nju.edu.cn

2016-06-01

The X-ray afterglow of GRB 130831A shows an “internal plateau” with a decay slope of ∼0.8, followed by a steep drop at around 10{sup 5} s with a slope of ∼6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which themore » magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with an approximately constant flux which is compatible with observation. Assuming that the magnetar wind has a negligible contribution in the optical band, we interpret the optical afterglow as the forward shock emission by invoking the energy injection from a continuously refreshed shock following the prompt emission phase. It is shown that our model can basically describe the temporal evolution of the multi-band afterglow of GRB 130831A.« less

Relativistic simulations of long-lived reverse shocks in stratified ejecta: the origin of flares in GRB afterglows

NASA Astrophysics Data System (ADS)

Lamberts, A.; Daigne, F.

2018-02-01

The X-ray light curves of the early afterglow phase from gamma-ray bursts (GRBs) present a puzzling variability, including flares. The origin of these flares is still debated, and often associated with a late activity of the central engine. We discuss an alternative scenario where the central engine remains short-lived and flares are produced by the propagation of a long-lived reverse shock in a stratified ejecta. Here we focus on the hydrodynamics of the shock interactions. We perform one-dimensional ultrarelativistic hydrodynamic simulations with different initial internal structure in the GRB ejecta. We use them to extract bolometric light curves and compare with a previous study based on a simplified ballistic model. We find a good agreement between both approaches, with similar slopes and variability in the light curves, but identify several weaknesses in the ballistic model: the density is underestimated in the shocked regions, and more importantly, late shock reflections are not captured. With accurate dynamics provided by our hydrodynamic simulations, we confirm that internal shocks in the ejecta lead to the formation of dense shells. The interaction of the long-lived reverse shock with a dense shell then produces a fast and intense increase of the dissipated power. Assuming that the emission is due to the synchrotron radiation from shock-accelerated electrons, and that the external forward shock is radiatively inefficient, we find that this results in a bright flare in the X-ray light curve, with arrival times, shapes, and duration in agreement with the observed properties of X-ray flares in GRB afterglows.

Modeling the Multi-band Afterglow of GRB 130831A: Evidence for a Spinning-down Magnetar Dominated by Gravitational Wave Losses?

NASA Astrophysics Data System (ADS)

Zhang, Q.; Huang, Y. F.; Zong, H. S.

2016-06-01

The X-ray afterglow of GRB 130831A shows an “internal plateau” with a decay slope of ˜0.8, followed by a steep drop at around 105 s with a slope of ˜6. After the drop, the X-ray afterglow continues with a much shallower decay. The optical afterglow exhibits two segments of plateaus separated by a luminous optical flare, followed by a normal decay with a slope basically consistent with that of the late-time X-ray afterglow. The decay of the internal X-ray plateau is much steeper than what we expect in the simplest magnetar model. We propose a scenario in which the magnetar undergoes gravitational-wave-driven r-mode instability, and the spin-down is dominated by gravitational wave losses up to the end of the steep plateau, so that such a relatively steep plateau can be interpreted as the internal emission of the magnetar wind and the sharp drop can be produced when the magnetar collapses into a black hole. This scenario also predicts an initial X-ray plateau lasting for hundreds of seconds with an approximately constant flux which is compatible with observation. Assuming that the magnetar wind has a negligible contribution in the optical band, we interpret the optical afterglow as the forward shock emission by invoking the energy injection from a continuously refreshed shock following the prompt emission phase. It is shown that our model can basically describe the temporal evolution of the multi-band afterglow of GRB 130831A.

X-Ray Spectral Diagnostics of Gamma-Ray Burst Environments.

PubMed

Paerels; Kuulkers; Heise; Liedahl

2000-05-20

Recently, detection of discrete features in the X-ray afterglow spectra of GRB 970508 and GRB 970828 was reported. The most natural interpretation of these features is that they are redshifted Fe K emission complexes. The identification of the line emission mechanism has drastic implications for the inferred mass of radiating material and hence the nature of the burst site. X-ray spectroscopy provides a direct observational constraint on these properties of gamma-ray bursters. We briefly discuss how these constraints arise in the context of an application to the spectrum of GRB 970508.

GCN and VOEvent - A Status Report

NASA Technical Reports Server (NTRS)

Barthelmy, Scott

2006-01-01

The GRB Coordinates Network (GCN) has filled an important niche in the conduct and progress of research on GRB for more than 14 years. The methods used to collect and distribute the positions, lightcurves, spectra, and images on GRB is real time (a few seconds) will be reviewed. For the research on GRBs to continue to move forward and for other fields of transient astronomy to move forward, enhancements are needed to the GCN. VOEvents is one of those changes, and that addition will be described here. The enhanced system will be called VO-GCN.

Magnetostriction of a sphere: stress development during magnetization and residual stresses due to the remanent field

NASA Astrophysics Data System (ADS)

Reich, Felix A.; Rickert, Wilhelm; Stahn, Oliver; Müller, Wolfgang H.

2017-03-01

Based on the principles of rational continuum mechanics and electrodynamics (see Truesdell and Toupin in Handbuch der Physik, Springer, Berlin, 1960 or Kovetz in Electromagnetic theory, Oxford University Press, Oxford, 2000), we present closed-form solutions for the mechanical displacements and stresses of two different magnets. Both magnets are initially of spherical shape. The first (hard) magnet is uniformly magnetized and deforms due to the field induced by the magnetization. In the second problem of a (soft) linear-magnetic sphere, the deformation is caused by an applied external field, giving rise to magnetization. Both problems can be used for modeling parts of general magnetization processes. We will address the similarities between both settings in context with the solutions for the stresses and displacements. In both problems, the volumetric Lorentz force density vanishes. However, a Lorentz surface traction is present. This traction is determined from the magnetic flux density. Since the obtained displacements and stresses are small in magnitude, we may use Hooke's law with a small-strain approximation, resulting in the Lamé- Navier equations of linear elasticity theory. If gravity is neglected and azimuthal symmetry is assumed, these equations can be solved in terms of a series. This has been done by Hiramatsu and Oka (Int J Rock Mech Min Sci Geomech Abstr 3(2):89-90, 1966) before. We make use of their series solution for the displacements and the stresses and expand the Lorentz tractions of the analyzed problems suitably in order to find the expansion coefficients. The resulting algebraic system yields finite numbers of nonvanishing coefficients. Finally, the resulting stresses, displacements, principal strains and the Lorentz tractions are illustrated and discussed.

GRB 980425 host: [C II], [O I], and CO lines reveal recent enhancement of star formation due to atomic gas inflow

NASA Astrophysics Data System (ADS)

Michałowski, M. J.; Castro Cerón, J. M.; Wardlow, J. L.; Karska, A.; Messias, H.; van der Werf, P.; Hunt, L. K.; Baes, M.; Castro-Tirado, A. J.; Gentile, G.; Hjorth, J.; Le Floc'h, E.; Pérez-Martínez, R.; Nicuesa Guelbenzu, A.; Rasmussen, J.; Rizzo, J. R.; Rossi, A.; Sánchez-Portal, M.; Schady, P.; Sollerman, J.; Xu, D.

2016-11-01

Context. Accretion of gas from the intergalactic medium is required to fuel star formation in galaxies. We have recently suggested that this process can be studied using host galaxies of gamma-ray bursts (GRBs). Aims: Our aim is to test this possibility by studying in detail the properties of gas in the closest galaxy hosting a GRB (980425). Methods: We obtained the first ever far-infrared (FIR) line observations of a GRB host, namely Herschel/PACS resolved [C II] 158 μm and [O I] 63 μm spectroscopy, and an APEX/SHeFI CO(2-1) line detection and ALMA CO(1-0) observations of the GRB 980425 host. Results: The GRB 980425 host has elevated [C II]/FIR and [O I]/FIR ratios and higher values of star formation rates (SFR) derived from line ([C II], [O I], Hα) than from continuum (UV, IR, radio) indicators. [C II] emission exhibits a normal morphology, peaking at the galaxy centre, whereas [O I] is concentrated close to the GRB position and the nearby Wolf-Rayet region. The high [O I] flux indicates that there is high radiation field and high gas density at these positions, as derived from modelling of photo-dissociation regions. The [C II]/CO luminosity ratio of the GRB 980425 host is close to the highest values found for local star-forming galaxies. Indeed, its CO-derived molecular gas mass is low given its SFR and metallicity, but the [C II]-derived molecular gas mass is close to the expected value. Conclusions: The [O I] and H I concentrations and the high radiation field and density close to the GRB position are consistent with the hypothesis of a very recent (at most a few tens of Myr ago) inflow of atomic gas triggering star formation. In this scenario dust has not had time to build up (explaining high line-to-continuum ratios). Such a recent enhancement of star formation activity would indeed manifest itself in high SFRline/SFRcontinuum ratios because the line indicators are sensitive only to recent (≲10 Myr) activity, whereas the continuum indicators measure the SFR averaged over much longer periods ( 100 Myr). Within a sample of 32 other GRB hosts, 20 exhibit SFRline/SFRcontinuum> 1 with a mean ratio of 1.74 ± 0.32. This is consistent with a very recent enhancement of star formation that is common among GRB hosts, so galaxies that have recently experienced inflow of gas may preferentially host stars exploding as GRBs. Therefore GRBs may be used to select a unique sample of galaxies that is suitable for the investigation of recent gas accretion. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

THE SWIFT GRB HOST GALAXY LEGACY SURVEY. II. REST-FRAME NEAR-IR LUMINOSITY DISTRIBUTION AND EVIDENCE FOR A NEAR-SOLAR METALLICITY THRESHOLD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perley, D. A.; Tanvir, N. R.; Hjorth, J.

2016-01-20

We present rest-frame near-IR (NIR) luminosities and stellar masses for a large and uniformly selected population of gamma-ray burst (GRB) host galaxies using deep Spitzer Space Telescope imaging of 119 targets from the Swift GRB Host Galaxy Legacy Survey spanning 0.03 < z < 6.3, and we determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the GRB host population across cosmic history. We find a rapid increase in the characteristic NIR host luminosity between z ∼ 0.5 and z ∼ 1.5, but little variation between z ∼ 1.5 and z ∼ 5. Dust-obscured GRBs dominate the massive host population but are only rarely seen associated withmore » low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high redshift while low-mass star-forming galaxies retain little dust in their interstellar medium. Comparing our luminosity distributions with field surveys and measurements of the high-z mass–metallicity relation, our results have good consistency with a model in which the GRB rate per unit star formation is constant in galaxies with gas-phase metallicity below approximately the solar value but heavily suppressed in more metal-rich environments. This model also naturally explains the previously reported “excess” in the GRB rate beyond z ≳ 2; metals stifle GRB production in most galaxies at z < 1.5 but have only minor impact at higher redshifts. The metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. Our observations also constrain the fraction of cosmic star formation in low-mass galaxies undetectable to Spitzer to be small at z < 4.« less

Growth Factor Receptor–Bound Protein 2 Contributes to (Hem)Immunoreceptor Tyrosine-Based Activation Motif–Mediated Signaling in Platelets

PubMed Central

Morowski, Martina; Schiessl, Sarah; Schäfer, Carmen M.; Watson, Stephanie K.; Hughes, Craig E.; Ackermann, Jochen A.; Radtke, Daniel; Hermanns, Heike M.; Watson, Steve P.; Nitschke, Lars; Nieswandt, Bernhard

2015-01-01

Rationale Platelets are anuclear cell fragments derived from bone marrow megakaryocytes (MKs) that safeguard vascular integrity but may also cause pathological vessel occlusion. One major pathway of platelet activation is triggered by 2 receptors that signal through an (hem)immunoreceptor tyrosine-based activation motif (ITAM), the activating collagen receptor glycoprotein (GP) VI and the C-type lectin-like receptor 2 (CLEC-2). Growth factor receptor–bound protein 2 (Grb2) is a ubiquitously expressed adapter molecule involved in signaling processes of numerous receptors in different cell types, but its function in platelets and MKs is unknown. Objective We tested the hypothesis that Grb2 is a crucial adapter protein in (hem)immunoreceptor tyrosine-based activation motif signaling in platelets. Methods and Results Here, we show that genetic ablation of Grb2 in MKs and platelets did not interfere with MK differentiation or platelet production. However, Grb2-deficiency severely impaired glycoprotein VI–mediated platelet activation because of defective stabilization of the linker of activated T-cell (LAT) signalosome and activation of downstream signaling proteins that resulted in reduced adhesion, aggregation, and coagulant activity on collagen in vitro. Similarly, CLEC-2–mediated signaling was impaired in Grb2-deficient platelets, whereas the cells responded normally to stimulation of G protein–coupled receptors. In vivo, this selective (hem) immunoreceptor tyrosine-based activation motif signaling defect resulted in prolonged bleeding times but affected arterial thrombus formation only after concomitant treatment with acetylsalicylic acid, indicating that defective glycoprotein VI signaling in the absence of Grb2 can be compensated through thromboxane A2–induced G protein–coupled receptor signaling pathways. Conclusions These results reveal an important contribution of Grb2 in (hem)immunoreceptor tyrosine-based activation motif signaling in platelets in hemostasis and thrombosis by stabilizing the LAT signalosome. PMID:24265393

An Artificial Intelligence Classification Tool and Its Application to Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Hakkila, Jon; Haglin, David J.; Roiger, Richard J.; Giblin, Timothy; Paciesas, William S.; Pendleton, Geoffrey N.; Mallozzi, Robert S.

2004-01-01

Despite being the most energetic phenomenon in the known universe, the astrophysics of gamma-ray bursts (GRBs) has still proven difficult to understand. It has only been within the past five years that the GRB distance scale has been firmly established, on the basis of a few dozen bursts with x-ray, optical, and radio afterglows. The afterglows indicate source redshifts of z=1 to z=5, total energy outputs of roughly 10(exp 52) ergs, and energy confined to the far x-ray to near gamma-ray regime of the electromagnetic spectrum. The multi-wavelength afterglow observations have thus far provided more insight on the nature of the GRB mechanism than the GRB observations; far more papers have been written about the few observed gamma-ray burst afterglows in the past few years than about the thousands of detected gamma-ray bursts. One reason the GRB central engine is still so poorly understood is that GRBs have complex, overlapping characteristics that do not appear to be produced by one homogeneous process. At least two subclasses have been found on the basis of duration, spectral hardness, and fluence (time integrated flux); Class 1 bursts are softer, longer, and brighter than Class 2 bursts (with two second durations indicating a rough division). A third GRB subclass, overlapping the other two, has been identified using statistical clustering techniques; Class 3 bursts are intermediate between Class 1 and Class 2 bursts in brightness and duration, but are softer than Class 1 bursts. We are developing a tool to aid scientists in the study of GRB properties. In the process of developing this tool, we are building a large gamma-ray burst classification database. We are also scientifically analyzing some GRB data as we develop the tool. Tool development thus proceeds in tandem with the dataset for which it is being designed. The tool invokes a modified KDD (Knowledge Discovery in Databases) process, which is described as follows.

Lorentz-violating electrodynamics and the cosmic microwave background.

PubMed

Kostelecký, V Alan; Mewes, Matthew

2007-07-06

Possible Lorentz-violating effects in the cosmic microwave background are studied. We provide a systematic classification of renormalizable and nonrenormalizable operators for Lorentz violation in electrodynamics and use polarimetric observations to search for the associated violations.

Tests of Lorentz Symmetry with Electrodynamics

NASA Astrophysics Data System (ADS)

Bailey, Quentin; Kostelecky, Alan

2004-05-01

Lorentz and CPT violation is a promising candidate signal for Planck-scale physics. Low-energy effects of Lorentz and CPT violation are described by the general theoretical framework called the Standard-Model Extension (SME). This talk focuses on Lorentz-violating effects arising in the limit of classical electrodynamics. Analysis of the theory shows that suitable experiments could improve by several orders of magnitude on the sensitivities achieved in modern Michelson-Morley and Kennedy-Thorndike tests.

Physics of the Lorentz Group

NASA Astrophysics Data System (ADS)

Başkal, Sibel

2015-11-01

This book explains the Lorentz mathematical group in a language familiar to physicists. While the three-dimensional rotation group is one of the standard mathematical tools in physics, the Lorentz group of the four-dimensional Minkowski space is still very strange to most present-day physicists. It plays an essential role in understanding particles moving at close to light speed and is becoming the essential language for quantum optics, classical optics, and information science. The book is based on papers and books published by the authors on the representations of the Lorentz group based on harmonic oscillators and their applications to high-energy physics and to Wigner functions applicable to quantum optics. It also covers the two-by-two representations of the Lorentz group applicable to ray optics, including cavity, multilayer and lens optics, as well as representations of the Lorentz group applicable to Stokes parameters and the Poincaré sphere on polarization optics.

Lorentz violation, gravitoelectromagnetic field and Bhabha scattering

NASA Astrophysics Data System (ADS)

Santos, A. F.; Khanna, Faqir C.

2018-01-01

Lorentz symmetry is a fundamental symmetry in the Standard Model (SM) and in General Relativity (GR). This symmetry holds true for all models at low energies. However, at energies near the Planck scale, it is conjectured that there may be a very small violation of Lorentz symmetry. The Standard Model Extension (SME) is a quantum field theory that includes a systematic description of Lorentz symmetry violations in all sectors of particle physics and gravity. In this paper, SME is considered to study the physical process of Bhabha Scattering in the Gravitoelectromagnetism (GEM) theory. GEM is an important formalism that is valid in a suitable approximation of general relativity. A new nonminimal coupling term that violates Lorentz symmetry is used in this paper. Differential cross-section for gravitational Bhabha scattering is calculated. The Lorentz violation contributions to this GEM scattering cross-section are small and are similar in magnitude to the case of the electromagnetic field.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahlgren, Björn; Larsson, Josefin; Nymark, Tanja

The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. We fit Fermi GRB data with a photospheric emission model which includes dissipation of the jet kinetic energy below the photosphere. The resulting spectra are dominated by Comptonization and contain no significant contribution from synchrotron radiation. In order to fit to the data, we span a physically motivated part of the model's parameter space and create DREAM (Dissipation with Radiative Emission as A table Model), a table model for XSPEC. Here, we show that this model can describemore » different kinds of GRB spectra, including GRB 090618, representing a typical Band function spectrum, and GRB 100724B, illustrating a double peaked spectrum, previously fitted with a Band+blackbody model, suggesting they originate from a similar scenario. We also suggest that the main difference between these two types of bursts is the optical depth at the dissipation site.« less

General Features of GRB 030329 in the EMBH Model

NASA Astrophysics Data System (ADS)

Bernardini, Maria Grazia; Bianco, Carlo Luciano; Ruffini, Remo; Xue, She-Sheng; Chardonnet, Pascal; Fraschetti, Federico

2006-02-01

GRB 030329 is considered within the EMBH model. We determine the three free parameters and deduce its luminosity in given energy bands comparing it with the observations. The observed substructures are compared with the predictions of the model: by applying the result that substructures observed in the extended afterglow peak emission (E-APE) do indeed originate in the collision of the accelerated baryonic matter (ABM) pulse with the inhomogeneities in the interstellar medium around the black-hole, masks of density inhomogeneities are considered in order to reproduce the observed temporal substructures. The induced supernova concept is applied to this system and the general consequences that we are witnessing are the formation of a cosmological thriptych of a black hole originating the GRB 030329, the supernova SN2003dh and a young neutron star. Analogies to the system GRB 980425-SN1998bw are outlined.

NuSTAR observations of GRB 130427A establish a single component synchrotron afterglow origin for the late optical to multi-GEV emission

DOE PAGES

Kouveliotou, Chryssa; Granot, J.; Racusin, J. L.; ...

2013-11-21

Here, GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest GRB fluence ever recorded. The afterglow of GRB 130427A was bright enough for the Nuclear Spectroscopic Telescope ARray ( NuSTAR) to observe it in the 3-79 keV energy range long after its prompt emission (~1.5 and 5 days). This range, where afterglow observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi, and ground-based optical data, NuSTAR observations unambiguously establish a single afterglow spectral component from optical to multi-GeV energies a day after the event, which is almost certainly synchrotron radiation.more » Such an origin of the late-time Fermi/Large Area Telescope >10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.« less

BATSE analysis techniques for probing the GRB spatial and luminosity distributions

NASA Technical Reports Server (NTRS)

Hakkila, Jon; Meegan, Charles A.

1992-01-01

The Burst And Transient Source Experiment (BATSE) has measured homogeneity and isotropy parameters from an increasingly large sample of observed gamma-ray bursts (GRBs), while also maintaining a summary of the way in which the sky has been sampled. Measurement of both of these are necessary for any study of the BATSE data statistically, as they take into account the most serious observational selection effects known in the study of GRBs: beam-smearing and inhomogeneous, anisotropic sky sampling. Knowledge of these effects is important to analysis of GRB angular and intensity distributions. In addition to determining that the bursts are local, it is hoped that analysis of such distributions will allow boundaries to be placed on the true GRB spatial distribution and luminosity function. The technique for studying GRB spatial and luminosity distributions is direct. Results of BATSE analyses are compared to Monte Carlo models parameterized by a variety of spatial and luminosity characteristics.

Swift and Fermi observations of the early afterglow of the short gamma-ray burst 090510

DOE PAGES

De Pasquale, M.

2010-01-14

Here, we present the observations of GRB090510 performed by the Fermi Gamma-Ray Space Telescope and the Swift observatory. In a GeV range, we detected a bright, short burst that shows an extended emission. Furthermore, its optical emission initially rises, a feature so far observed only in long bursts, while the X-ray flux shows an initial shallow decrease, followed by a steeper decay. This exceptional behavior enables us to investigate the physical properties of the gamma-ray burst outflow, poorly known in short bursts. Here, we discuss internal and external shock models for the broadband energy emission of this object.

BEAM ON TARGET MODEL Produces All Gamma Ray Burst Phenomena Including Afterglow

NASA Astrophysics Data System (ADS)

Greyber, H.

2000-12-01

While one must applaud the splendid research by L. Piro et al and L. Amati et al reported in SCIENCE recently, one must question, as M. Rees and S. Woolsey have done, their conclusion that a ``supranova model" is the only explanation for these new X-ray observations. In fact L. Piro was quoted as saying, ``Our data helps rule out the scenario where two neutron stars or black holes collide. We think GRBs result from something similar to a supernova explosion, but much more powerful." A relatively unknown physical model for GRBs, Greyber's Beam On Target model (BOT), dating back to the first CGRO observations, can plausibly explain the iron emission lines observed for GRB991216, and also the mass of the dense medium within a light-day of the GRB being roughly equivalent to at least one-tenth solar mass, as well as the initial shedding of material followed by the GRB event. When a galaxy forms under gravitational collapse in the presence of a primordial magnetic field, Mestel and Strittmatter demonstrated that, for finite Ohmic diffusion, a growing equatorial current loop is formed. Even if this stable ``Storage Ring" has only 10exp-9 of the total energy released during a typical galaxy's formation, the relativistic beam can possess 10exp58 ergs. The GRB ``fireball" occurs when a target star races across the powerful beam, blowing off target material as a hot, rapidly expanding plasma cloud, simulating an explosion. Since currents in space are known to be sometimes filamentary, sharp millisecond spikes can be expected in some GRBs. Proton and alpha particle nuclear reactions produce a gamma ray beam. Beam particles impinging on denser cloud material create an electromagnetic shower, producing X-ray, optical and radio radiation. Since the Storage Ring has an intense magnetic field around it, synchrotron radiation is expected. The beam, striking a highly evolved massive target star, produces the iron emission lines. H. D. Greyber, in ``After the Dark Ages:When Galaxies Were Young", A.I.P. Confer. Proc. no.470, 388, (1999) L. Mestel & P. Strittmatter, Mon. Not. Royal Astron. Society, 137, 95, (1967)

Terrestrial ozone depletion due to a Milky Way gamma-ray burst

NASA Astrophysics Data System (ADS)

Thomas, Brian C.

Gamma-Ray Bursts (GRBs) are short, incredibly powerful astrophysical events which produce a flux of radiation detectable across the observable universe. A GRB within our own galaxy could cause major damage to the Earth's biosphere. Rate estimates suggest that at least one GRB has occurred within a dangerous range (about 2 kpc) in the last billion years. The gamma radiation from such a burst would quickly deplete much of the Earth's protective ozone layer, allowing an increase in solar UVB radiation reaching the surface. This radiation is harmful to life, causing sunburn and damaging DNA. In addition, NO 2 produced in the atmosphere would cause a decrease in visible sunlight reaching the surface and could cause global cooling. Nitric acid rain could stress portions of the biosphere, but the increased nitrate deposition could be helpful to land plants. We have used a two-dimensional atmospheric model to investigate the effects on the Earth's atmosphere of a GRB. We have simulated bursts delivering a range of fluences, at various latitudes, at the equinoxes and solstices, and at different times of day. We have computed DNA damage caused by increased solar UVB radiation, reduction in solar visible light due to NO 2 opacity; and deposition of nitrates through rainout of HNO 3 . For a "typical" burst in the last billion years, we find globally averaged ozone depletion up to 38%. Localized depletion reaches as much as 74%. Significant global depletion (at least 10%) persists up to about 7 years after the burst. Our results depend strongly on time of year and latitude over which the burst occurs. We find DNA damage of up to 16 times the normal annual global average, with greatest damage occurring at low to mid latitudes. We find reductions in visible sunlight of a few percent, primarily in the polar regions. Nitrate deposition similar to or slightly greater than that currently caused by lightning is also observed. We find support in our results for the hypothesis that the Late Ordovician mass extinction may have been initiated by a GRB and this connection is briefly discussed.

GRB 091127: The Cooling Break Race on Magnetic Fuel

NASA Technical Reports Server (NTRS)

Filgas, R.; Greiner, J.; Schady, P.; Kruhler, T.; Updike, A. C.; Klose, S.; Nardini, M.; Kann, D. A.; Rossi, A.; Sudilovsky, V.;

GRB/GW Association: Long-Short GRB Candidates, Time Lag, Measuring Gravitational Wave Velocity, and Testing Einstein’s Equivalence Principle

NASA Astrophysics Data System (ADS)

Li, Xiang; Hu, Yi-Ming; Fan, Yi-Zhong; Wei, Da-Ming

2016-08-01

Short-duration gamma-ray bursts (SGRBs) are widely believed to be powered by the mergers of compact binaries, such as binary neutron stars or possibly neutron star-black hole binaries. Though the prospect of detecting SGRBs with gravitational wave (GW) signals by the advanced Laser Interferometer Gravitational-Wave Observatory (LIGO)/VIRGO network is promising, no known SGRB has been found within the expected advanced LIGO/VIRGO sensitivity range for binary neutron star systems. We find, however, that the two long-short GRBs (GRB 060505 and GRB 060614) may be within the horizon of advanced GW detectors. In the upcoming era of GW astronomy, the merger origin of some long-short GRBs, as favored by the macronova signature displayed in GRB 060614, can be unambiguously tested. The model-dependent time lags between the merger and the onset of the prompt emission of the GRB are estimated. The comparison of such time lags between model predictions and the real data expected in the era of the GW astronomy would be helpful in revealing the physical processes taking place at the central engine (including the launch of the relativistic outflow, the emergence of the outflow from the dense material ejected during the merger, and the radiation of gamma rays). We also show that the speed of GWs, with or without a simultaneous test of Einstein’s equivalence principle, can be directly measured to an accuracy of ˜ 3× {10}-8 {cm} {{{s}}}-1 or even better in the advanced LIGO/VIRGO era.

The luminous, massive and solar metallicity galaxy hosting the Swift γ-ray burst GRB 160804A at z = 0.737

NASA Astrophysics Data System (ADS)

Heintz, K. E.; Malesani, D.; Wiersema, K.; Jakobsson, P.; Fynbo, J. P. U.; Savaglio, S.; Cano, Z.; Covino, S.; D'Elia, V.; Gomboc, A.; Hammer, F.; Kaper, L.; Milvang-Jensen, B.; Møller, P.; Piranomonte, S.; Selsing, J.; Rhodin, N. H. P.; Tanvir, N. R.; Thöne, C. C.; de Ugarte Postigo, A.; Vergani, S. D.; Watson, D.

2018-02-01

We here present the spectroscopic follow-up observations with VLT/X-shooter of the Swift long-duration gamma-ray burst GRB 160804A at z = 0.737. Typically, GRBs are found in low-mass, metal-poor galaxies that constitute the sub-luminous population of star-forming galaxies. For the host galaxy of the GRB presented here, we derive a stellar mass of log (M*/ M⊙) = 9.80 ± 0.07, a roughly solar metallicity (12 + log (O/H) = 8.74 ± 0.12) based on emission line diagnostics, and an infrared luminosity of M3.6/(1 + z) = -21.94 mag, but find it to be dust-poor (E(B - V) < 0.05 mag). This establishes the galaxy hosting GRB 160804A as one of the most luminous, massive and metal-rich GRB hosts at z < 1.5. Furthermore, the gas-phase metallicity is found to be representative of the physical conditions of the gas close to the explosion site of the burst. The high metallicity of the host galaxy is also observed in absorption, where we detect several strong Fe II transitions as well as Mg II and Mg I. Although host galaxy absorption features are common in GRB afterglow spectra, we detect absorption from strong metal lines directly in the host continuum (at a time when the afterglow was contributing to < 15 per cent). Finally, we discuss the possibility that the geometry and state of the absorbing and emitting gas are indicative of a galactic scale outflow expelled at the final stage of two merging galaxies.

Gamma-Ray Bursts in the Swift Era

NASA Technical Reports Server (NTRS)

Gehrels, Neil; Cannizzo, John K.; Norris, Jay P.

2007-01-01

GRB research has undergone a revolution in the last two years. The launch of Swift, with its rapid slewing capability, has greatly increased the number and quality of GRB localizations and X-ray and optical afterglow lightcurves. Over 160 GRBs have been detected, and nearly all that have been followed up with the on-board narrow field telescopes. Advances in our understanding of short GRBs have been spectacular. The detection of X-ray afterglows has led to accurate localizations from ground based observatories, which have given host identifications and redshifts. Theoretical models for short GRB progenitors have, for the first time, been placed on a sound foundation. The hosts for the short GRBs differ in a fundamental way from the long GRB hosts: short GRBs tend to occur in non-star forming galaxies or regions, whereas long GRBs are strongly concentrated within star forming regions. Observations are consistent with a binary neutron star merger model, but other models involving old stellar populations are also viable. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at zeta approx. 5-6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova. The prospects for future progress are excellent given the >10 year orbital lifetime of the Swift satellite.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruehler, Thomas; Malesani, Daniele; Milvang-Jensen, Bo

We present simultaneous optical and near-infrared (NIR) spectroscopy of 19 Swift {gamma}-ray burst (GRB) host galaxies observed with the VLT/X-shooter with the aim of measuring their redshifts. Galaxies were selected from The Optically Unbiased GRB Host (TOUGH) survey (15 of the 19 galaxies) or because they hosted GRBs without a bright optical afterglow. Here we provide emission-line redshifts for 13 of the observed galaxies with brightnesses between F606W > 27 mag and R = 22.9 mag (median R-tilde =24.6 mag). The median redshift is z-tilde =2.1 for all hosts and z-tilde =2.3 for the TOUGH hosts. Our new data significantlymore » improve the redshift completeness of the TOUGH survey, which now stands at 77% (53 out of 69 GRBs). They furthermore provide accurate redshifts for nine prototype dark GRBs (e.g., GRB 071021 at z = 2.452 and GRB 080207 at z = 2.086), which are exemplary of GRBs where redshifts are challenging to obtain via afterglow spectroscopy. This establishes X-shooter spectroscopy as an efficient tool for redshift determination of faint, star-forming, high-redshift galaxies such as GRB hosts. It is hence a further step toward removing the bias in GRB samples that is caused by optically dark events, and provides the basis for a better understanding of the conditions in which GRBs form. The distribution of column densities as measured from X-ray data (N{sub H,X}), for example, is closely related to the darkness of the afterglow and skewed toward low N{sub H,X} values in samples that are dominated by bursts with bright optical afterglows.« less

Vacuum Cherenkov radiation for Lorentz-violating fermions

NASA Astrophysics Data System (ADS)

Schreck, M.

2017-11-01

The current work focuses on the process of vacuum Cherenkov radiation for Lorentz-violating fermions that are described by the minimal standard-model extension (SME). To date, most considerations of this important hypothetical process have been restricted to Lorentz-violating photons, as the necessary theoretical tools for the SME fermion sector have not been available. With their development in a very recent paper, we are now in a position to compute the decay rates based on a modified Dirac theory. Two realizations of the Cherenkov process are studied. In the first scenario, the spin projection of the incoming fermion is assumed to be conserved, and in the second, the spin projection is allowed to flip. The first type of process is shown to be still forbidden for the dimensionful a and b coefficients where there are strong indications that it is energetically disallowed for the H coefficients, as well. However, it is rendered possible for the dimensionless c , d , e , f , and g coefficients. For large initial fermion energies, the decay rates for the c and d coefficients were found to grow linearly with momentum and to be linearly suppressed by the smallness of the Lorentz-violating coefficient where for the e , f , and g coefficients this suppression is even quadratic. The decay rates vanish in the vicinity of the threshold, as expected. The decay including a fermion spin-flip plays a role for the spin-nondegenerate operators and it was found to occur for the dimensionful b and H coefficients as well as for the dimensionless d and g . The characteristics of this process differ much from the properties of the spin-conserving one, e.g., there is no threshold. Based on experimental data of ultra-high-energy cosmic rays, new constraints on Lorentz violation in the quark sector are obtained from the thresholds. However, it does not seem to be possible to derive bounds from the spin-flip decays. This work reveals the usefulness of the quantum field theoretic methods recently developed to study the phenomenology of high-energy fermions within the framework of the SME.

Comment on 'Noncommutative gauge theories and Lorentz symmetry'

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iorio, Alfredo

2008-02-15

We show that Lorentz symmetry is generally absent for noncommutative (Abelian) gauge theories and obtain a compact formula for the divergence of the Noether currents that allows a thorough study of this instance of symmetry violation. We use that formula to explain why the results of ''Noncommutative gauge theories and Lorentz symmetry'', Phys. Rev. D 70, 125004 (2004) by R. Banerjee, B. Chakraborty, and K. Kumar, interpreted there as new criteria for Lorentz invariance, are in fact just a particular case of the general expression for Lorentz violation obtained here. Finally, it is suggested that the divergence formula should holdmore » in a vast class of cases, such as, for instance, the standard model extension.« less

Propagation of partially coherent Lorentz-Gauss vortex beam through oceanic turbulence.

PubMed

Liu, Dajun; Yin, Hongming; Wang, Guiqiu; Wang, Yaochuan

2017-11-01

The partially coherent Lorentz-Gauss vortex beam generated by a Schell-model source has been introduced. Based on the extended Huygens-Fresnel principle, the cross-spectral density function of a partially coherent Lorentz-Gauss vortex beam propagating in oceanic turbulence is derived. The influences of coherence length, topological charge M, and oceanic turbulence on the spreading properties and position of the coherence vortex for a partially coherent Lorentz-Gauss vortex beam are analyzed in detail. The results show that a partially coherent Lorentz-Gauss vortex beam propagating in stronger oceanic turbulence will evolve into a Gaussian-like beam more rapidly as the propagation distance increases, and the number of coherent vortices will change.

A Method to Constrain Mass and Spin of GRB Black Holes within the NDAF Model

NASA Astrophysics Data System (ADS)

Liu, Tong; Xue, Li; Zhao, Xiao-Hong; Zhang, Fu-Wen; Zhang, Bing

2016-04-01

Black holes (BHs) hide themselves behind various astronomical phenomena and their properties, I.e., mass and spin, are usually difficult to constrain. One leading candidate for the central engine model of gamma-ray bursts (GRBs) invokes a stellar mass BH and a neutrino-dominated accretion flow (NDAF), with the relativistic jet launched due to neutrino-anti-neutrino annihilations. Such a model gives rise to a matter-dominated fireball, and is suitable to interpret GRBs with a dominant thermal component with a photospheric origin. We propose a method to constrain BH mass and spin within the framework of this model and apply the method to the thermally dominant GRB 101219B, whose initial jet launching radius, r0, is constrained from the data. Using our numerical model of NDAF jets, we estimate the following constraints on the central BH: mass MBH ˜ 5-9 M⊙, spin parameter a* ≳ 0.6, and disk mass 3 M⊙ ≲ Mdisk ≲ 4 M⊙. Our results also suggest that the NDAF model is a competitive candidate for the central engine of GRBs with a strong thermal component.

Search for long-lived gravitational-wave transients coincident with long gamma-ray bursts

NASA Astrophysics Data System (ADS)

Aasi, J.; Abadie, J.; Abbott, B. P.; Abbott, R.; Abbott, T.; Abernathy, M. R.; Accadia, T.; Acernese, F.; Adams, C.; Adams, T.; Adhikari, R. X.; Affeldt, C.; Agathos, M.; Aggarwal, N.; Aguiar, O. D.; Ajith, P.; Allen, B.; Allocca, A.; Amador Ceron, E.; Amariutei, D.; Anderson, R. A.; Anderson, S. B.; Anderson, W. G.; Arai, K.; Araya, M. C.; Arceneaux, C.; Areeda, J.; Ast, S.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Austin, L.; Aylott, B. E.; Babak, S.; Baker, P. T.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; Barker, D.; Barnum, S. H.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J.; Bauchrowitz, J.; Bauer, Th. S.; Bebronne, M.; Behnke, B.; Bejger, M.; Beker, M. G.; Bell, A. S.; Bell, C.; Belopolski, I.; Bergmann, G.; Berliner, J. M.; Bersanetti, D.; Bertolini, A.; Bessis, D.; Betzwieser, J.; Beyersdorf, P. T.; Bhadbhade, T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Blom, M.; Bock, O.; Bodiya, T. P.; Boer, M.; Bogan, C.; Bond, C.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bowers, J.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; Brannen, C. A.; Brau, J. E.; Breyer, J.; Briant, T.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brückner, F.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Calderón Bustillo, J.; Calloni, E.; Camp, J. B.; Campsie, P.; Cannon, K. C.; Canuel, B.; Cao, J.; Capano, C. D.; Carbognani, F.; Carbone, L.; Caride, S.; Castiglia, A.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chakraborty, R.; Chalermsongsak, T.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Chen, X.; Chen, Y.; Chincarini, A.; Chiummo, A.; Cho, H. S.; Chow, J.; Christensen, N.; Chu, Q.; Chua, S. S. Y.; Chung, S.; Ciani, G.; Clara, F.; Clark, D. E.; Clark, J. A.; Cleva, F.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Colombini, M.; Constancio, M., Jr.; Conte, A.; Conte, R.; Cook, D.; Corbitt, T. R.; Cordier, M.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M. W.; Coulon, J.-P.; Countryman, S.; Couvares, P.; Coward, D. M.; Cowart, M.; Coyne, D. C.; Craig, K.; Creighton, J. D. E.; Creighton, T. D.; Crowder, S. G.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Dal Canton, T.; Damjanic, M.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G. S.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; Debreczeni, G.; Degallaix, J.; Del Pozzo, W.; Deleeuw, E.; Deléglise, S.; Denker, T.; Dent, T.; Dereli, H.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Di Virgilio, A.; Díaz, M.; Dietz, A.; Dmitry, K.; Donovan, F.; Dooley, K. L.; Doravari, S.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edwards, M.; Effler, A.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Endrőczi, G.; Essick, R.; Etzel, T.; Evans, K.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fang, Q.; Farinon, S.; Farr, B.; Farr, W.; Favata, M.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Ferrini, F.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Fisher, R.; Flaminio, R.; Foley, E.; Foley, S.; Forsi, E.; Fotopoulos, N.; Fournier, J.-D.; Franco, S.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Fritschel, P.; Frolov, V. V.; Fujimoto, M.-K.; Fulda, P.; Fyffe, M.; Gair, J.; Gammaitoni, L.; Garcia, J.; Garufi, F.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; Gergely, L.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gil-Casanova, S.; Gill, C.; Gleason, J.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gordon, N.; Gorodetsky, M. L.; Gossan, S.; Goßler, S.; Gouaty, R.; Graef, C.; Graff, P. B.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Griffo, C.; Groot, P.; Grote, H.; Grover, K.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, B.; Hall, E.; Hammer, D.; Hammond, G.; Hanke, M.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Heefner, J.; Heidmann, A.; Heintze, M.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Holtrop, M.; Hong, T.; Hooper, S.; Horrom, T.; Hosken, D. J.; Hough, J.; Howell, E. J.; Hu, Y.; Hua, Z.; Huang, V.; Huerta, E. A.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh, M.; Huynh-Dinh, T.; Iafrate, J.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Iyer, B. R.; Izumi, K.; Jacobson, M.; James, E.; Jang, H.; Jang, Y. J.; Jaranowski, P.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Haris, K.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Kasprzack, M.; Kasturi, R.; Katsavounidis, E.; Katzman, W.; Kaufer, H.; Kaufman, K.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kéfélian, F.; Keitel, D.; Kelley, D. B.; Kells, W.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, B. K.; Kim, C.; Kim, K.; Kim, N.; Kim, W.; Kim, Y.-M.; King, E. J.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kline, J.; Koehlenbeck, S.; Kokeyama, K.; Kondrashov, V.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kremin, A.; Kringel, V.; Królak, A.; Kucharczyk, C.; Kudla, S.; Kuehn, G.; Kumar, A.; Kumar, P.; Kumar, R.; Kurdyumov, R.; Kwee, P.; Landry, M.; Lantz, B.; Larson, S.; Lasky, P. D.; Lawrie, C.; Lazzarini, A.; Le Roux, A.; Leaci, P.; Lebigot, E. O.; Lee, C.-H.; Lee, H. K.; Lee, H. M.; Lee, J.; Lee, J.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levine, B.; Lewis, J. B.; Lhuillier, V.; Li, T. G. F.; Lin, A. C.; Littenberg, T. B.; Litvine, V.; Liu, F.; Liu, H.; Liu, Y.; Liu, Z.; Lloyd, D.; Lockerbie, N. A.; Lockett, V.; Lodhia, D.; Loew, K.; Logue, J.; Lombardi, A. L.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J.; Luan, J.; Lubinski, M. J.; Lück, H.; Lundgren, A. P.; Macarthur, J.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magana-Sandoval, F.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Manca, G. M.; Mandel, I.; Mandic, V.; Mangano, V.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Martinelli, L.; Martynov, D.; Marx, J. N.; Mason, K.; Masserot, A.; Massinger, T. J.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; May, G.; Mazumder, N.; Mazzolo, G.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McIver, J.; Meacher, D.; Meadors, G. D.; Mehmet, M.; Meidam, J.; Meier, T.; Melatos, A.; Mendell, G.; Mercer, R. A.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Mikhailov, E. E.; Milano, L.; Miller, J.; Minenkov, Y.; Mingarelli, C. M. F.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moe, B.; Mohan, M.; Mohapatra, S. R. P.; Mokler, F.; Moraru, D.; Moreno, G.; Morgado, N.; Mori, T.; Morriss, S. R.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, C. L.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Munch, J.; Murphy, D.; Murray, P. G.; Mytidis, A.; Nagy, M. F.; Nanda Kumar, D.; Nardecchia, I.; Nash, T.; Naticchioni, L.; Nayak, R.; Necula, V.; Nelemans, G.; Neri, I.; Neri, M.; Newton, G.; Nguyen, T.; Nishida, E.; Nishizawa, A.; Nitz, A.; Nocera, F.; Nolting, D.; Normandin, M. E.; Nuttall, L. K.; Ochsner, E.; O'Dell, J.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oppermann, P.; O'Reilly, B.; Ortega Larcher, W.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Ou, J.; Overmier, H.; Owen, B. J.; Padilla, C.; Pai, A.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Paoletti, R.; Papa, M. A.; Paris, H.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Pedraza, M.; Peiris, P.; Penn, S.; Perreca, A.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pierro, V.; Pinard, L.; Pindor, B.; Pinto, I. M.; Pitkin, M.; Poeld, J.; Poggiani, R.; Poole, V.; Poux, C.; Predoi, V.; Prestegard, T.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Quintero, E.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Raja, S.; Rajalakshmi, G.; Rakhmanov, M.; Ramet, C.; Rapagnani, P.; Raymond, V.; Re, V.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Robertson, N. A.; Robinet, F.; Rocchi, A.; Roddy, S.; Rodriguez, C.; Rodruck, M.; Roever, C.; Rolland, L.; Rollins, J. G.; Romano, J. D.; Romano, R.; Romanov, G.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Salemi, F.; Sammut, L.; Sandberg, V.; Sanders, J.; Sannibale, V.; Santiago-Prieto, I.; Saracco, E.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Savage, R.; Schilling, R.; Schnabel, R.; Schofield, R. M. S.; Schreiber, E.; Schuette, D.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D.; Shah, S.; Shahriar, M. S.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sidery, T. L.; Siellez, K.; Siemens, X.; Sigg, D.; Simakov, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G. R.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, R. J. E.; Smith-Lefebvre, N. D.; Soden, K.; Son, E. J.; Sorazu, B.; Souradeep, T.; Sperandio, L.; Staley, A.; Steinert, E.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stevens, D.; Stochino, A.; Stone, R.; Strain, K. A.; Straniero, N.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szeifert, G.; Tacca, M.; Talukder, D.; Tang, L.; Tanner, D. B.; Tarabrin, S. P.; Taylor, R.; ter Braack, A. P. M.; Thirugnanasambandam, M. P.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Tiwari, V.; Tokmakov, K. V.; Tomlinson, C.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C. V.; Torrie, C. I.; Travasso, F.; Traylor, G.; Tse, M.; Ugolini, D.; Unnikrishnan, C. S.; Vahlbruch, H.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Heijningen, J.; van Veggel, A. A.; Vass, S.; Vasúth, M.; Vaulin, R.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Verkindt, D.; Verma, S.; Vetrano, F.; Viceré, A.; Vincent-Finley, R.; Vinet, J.-Y.; Vitale, S.; Vlcek, B.; Vo, T.; Vocca, H.; Vorvick, C.; Vousden, W. D.; Vrinceanu, D.; Vyachanin, S. P.; Wade, A.; Wade, L.; Wade, M.; Waldman, S. J.; Walker, M.; Wallace, L.; Wan, Y.; Wang, J.; Wang, M.; Wang, X.; Wanner, A.; Ward, R. L.; Was, M.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Welborn, T.; Wen, L.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D. J.; Whiting, B. F.; Wibowo, S.; Wiesner, K.; Wilkinson, C.; Williams, L.; Williams, R.; Williams, T.; Willis, J. L.; Willke, B.; Wimmer, M.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yancey, C. C.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yum, H.; Yvert, M.; Zadrożny, A.; Zanolin, M.; Zendri, J.-P.; Zhang, F.; Zhang, L.; Zhao, C.; Zhu, H.; Zhu, X. J.; Zotov, N.; Zucker, M. E.; Zweizig, J.

2013-12-01

Long gamma-ray bursts (GRBs) have been linked to extreme core-collapse supernovae from massive stars. Gravitational waves (GW) offer a probe of the physics behind long GRBs. We investigate models of long-lived (˜10-1000s) GW emission associated with the accretion disk of a collapsed star or with its protoneutron star remnant. Using data from LIGO’s fifth science run, and GRB triggers from the Swift experiment, we perform a search for unmodeled long-lived GW transients. Finding no evidence of GW emission, we place 90% confidence-level upper limits on the GW fluence at Earth from long GRBs for three waveforms inspired by a model of GWs from accretion disk instabilities. These limits range from F<3.5ergscm-2 to F<1200ergscm-2, depending on the GRB and on the model, allowing us to probe optimistic scenarios of GW production out to distances as far as ≈33Mpc. Advanced detectors are expected to achieve strain sensitivities 10× better than initial LIGO, potentially allowing us to probe the engines of the nearest long GRBs.

The Role of Magnetic Forces in Biology and Medicine

PubMed Central

Roth, Bradley J

2011-01-01

The Lorentz force (the force acting on currents in a magnetic field) plays an increasingly larger role in techniques to image current and conductivity. This review will summarize several applications involving the Lorentz force, including 1) magneto-acoustic imaging of current, 2) “Hall effect” imaging, 3) ultrasonically-induced Lorentz force imaging of conductivity, 4) magneto-acoustic tomography with magnetic induction, and 5) Lorentz force imaging of action currents using magnetic resonance imaging. PMID:21321309

Association between GRB2/Sos and insulin receptor substrate 1 is not sufficient for activation of extracellular signal-regulated kinases by interleukin-4: implications for Ras activation by insulin.

PubMed

Pruett, W; Yuan, Y; Rose, E; Batzer, A G; Harada, N; Skolnik, E Y

1995-03-01

Insulin receptor substrate 1 (IRS-1) mediates the activation of a variety of signaling pathways by the insulin and insulin-like growth factor 1 receptors by serving as a docking protein for signaling molecules with SH2 domains. We and others have shown that in response to insulin stimulation IRS-1 binds GRB2/Sos and have proposed that this interaction is important in mediating Ras activation by the insulin receptor. Recently, it has been shown that the interleukin (IL)-4 receptor also phosphorylates IRS-1 and an IRS-1-related molecule, 4PS. Unlike insulin, however, IL-4 fails to activate Ras, extracellular signal-regulated kinases (ERKs), or mitogen-activated protein kinases. We have reconstituted the IL-4 receptor into an insulin-responsive L6 myoblast cell line and have shown that IRS-1 is tyrosine phosphorylated to similar degrees in response to insulin and IL-4 stimulation in this cell line. In agreement with previous findings, IL-4 failed to activate the ERKs in this cell line or to stimulate DNA synthesis, whereas the same responses were activated by insulin. Surprisingly, IL-4's failure to activate ERKs was not due to a failure to stimulate the association of tyrosine-phosphorylated IRS-1 with GRB2/Sos; the amounts of GRB2/Sos associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. Moreover, the amounts of phosphatidylinositol 3-kinase activity associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Previous studies have indicated that activation of ERks in this cell line is dependent upon Ras since a dominant-negative Ras (Asn-17) blocks ERK activation by insulin. Our findings, taken in the context of previous work, suggest that binding of GRB2/Sos to Shc may be the predominant mechanism whereby insulin as well as cytokine receptors activate Ras.

The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy

NASA Astrophysics Data System (ADS)

Castro-Tirado, A. J.; Sokolov, V. V.; Gorosabel, J.; Castro Cerón, J. M.; Greiner, J.; Wijers, R. A. M. J.; Jensen, B. L.; Hjorth, J.; Toft, S.; Pedersen, H.; Palazzi, E.; Pian, E.; Masetti, N.; Sagar, R.; Mohan, V.; Pandey, A. K.; Pandey, S. B.; Dodonov, S. N.; Fatkhullin, T. A.; Afanasiev, V. L.; Komarova, V. N.; Moiseev, A. V.; Hudec, R.; Simon, V.; Vreeswijk, P.; Rol, E.; Klose, S.; Stecklum, B.; Zapatero-Osorio, M. R.; Caon, N.; Blake, C.; Wall, J.; Heinlein, D.; Henden, A.; Benetti, S.; Magazzù, A.; Ghinassi, F.; Tommasi, L.; Bremer, M.; Kouveliotou, C.; Guziy, S.; Shlyapnikov, A.; Hopp, U.; Feulner, G.; Dreizler, S.; Hartmann, D.; Boehnhardt, H.; Paredes, J. M.; Martí, J.; Xanthopoulos, E.; Kristen, H. E.; Smoker, J.; Hurley, K.

2001-05-01

Broad-band optical observations of the extraordinarily bright optical afterglow of the intense gamma-ray burst GRB 991208 started ~2.1 days after the event and continued until 4 Apr. 2000. The flux decay constant of the optical afterglow in the R-band is -2.30 +/- 0.07 up to ~5 days, which is very likely due to the jet effect, and it is followed by a much steeper decay with constant -3.2 +/- 0.2, the fastest one ever seen in a GRB optical afterglow. A negative detection in several all-sky films taken simultaneously with the event, that otherwise would have reached naked eye brightness, implies either a previous additional break prior to ~2 days after the occurrence of the GRB (as expected from the jet effect) or a maximum, as observed in GRB 970508. The existence of a second break might indicate a steepening in the electron spectrum or the superposition of two events, resembling GRB 000301C. Once the afterglow emission vanished, contribution of a bright underlying supernova was found on the basis of the late-time R-band measurements, but the light curve is not sufficiently well sampled to rule out a dust echo explanation. Our redshift determination of z = 0.706 indicates that GRB 991208 is at 3.7 Gpc (for Ho = 60 km s-1 Mpc-1, OMEGAo = 1 and LAMDAo = 0), implying an isotropic energy release of 1.15 x 1053 erg which may be relaxed by beaming by a factor >102. Precise astrometry indicates that the GRB coincides within 0.2" with the host galaxy, thus supporting a massive star origin. The absolute magnitude of the galaxy is MB = -18.2, well below the knee of the galaxy luminosity function and we derive a star-forming rate of (11.5 +/- 7.1) Msun yr-1, which is much larger than the present-day rate in our Galaxy. The quasi-simultaneous broad-band photometric spectral energy distribution of the afterglow was determined ~3.5 day after the burst (Dec. 12.0) implying a cooling frequency nuc below the optical band, i.e. supporting a jet model with p = -2.30 as the index of the power-law electron distribution.

Constraints and stability in vector theories with spontaneous Lorentz violation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bluhm, Robert; Gagne, Nolan L.; Potting, Robertus

2008-06-15

Vector theories with spontaneous Lorentz violation, known as bumblebee models, are examined in flat spacetime using a Hamiltonian constraint analysis. In some of these models, Nambu-Goldstone modes appear with properties similar to photons in electromagnetism. However, depending on the form of the theory, additional modes and constraints can appear that have no counterparts in electromagnetism. An examination of these constraints and additional degrees of freedom, including their nonlinear effects, is made for a variety of models with different kinetic and potential terms, and the results are compared with electromagnetism. The Hamiltonian constraint analysis also permits an investigation of the stabilitymore » of these models. For certain bumblebee theories with a timelike vector, suitable restrictions of the initial-value solutions are identified that yield ghost-free models with a positive Hamiltonian. In each case, the restricted phase space is found to match that of electromagnetism in a nonlinear gauge.« less

Lorentz Trial Function for the Hydrogen Atom: A Simple, Elegant Exercise

ERIC Educational Resources Information Center

Sommerfeld, Thomas

2011-01-01

The quantum semester of a typical two-semester physical chemistry course is divided into two parts. The initial focus is on quantum mechanics and simple model systems for which the Schrodinger equation can be solved in closed form, but it then shifts in the second half to atoms and molecules, for which no closed solutions exist. The underlying…

Lorentz covariance of loop quantum gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rovelli, Carlo; Speziale, Simone

2011-05-15

The kinematics of loop gravity can be given a manifestly Lorentz-covariant formulation: the conventional SU(2)-spin-network Hilbert space can be mapped to a space K of SL(2,C) functions, where Lorentz covariance is manifest. K can be described in terms of a certain subset of the projected spin networks studied by Livine, Alexandrov and Dupuis. It is formed by SL(2,C) functions completely determined by their restriction on SU(2). These are square-integrable in the SU(2) scalar product, but not in the SL(2,C) one. Thus, SU(2)-spin-network states can be represented by Lorentz-covariant SL(2,C) functions, as two-component photons can be described in the Lorentz-covariant Gupta-Bleulermore » formalism. As shown by Wolfgang Wieland in a related paper, this manifestly Lorentz-covariant formulation can also be directly obtained from canonical quantization. We show that the spinfoam dynamics of loop quantum gravity is locally SL(2,C)-invariant in the bulk, and yields states that are precisely in K on the boundary. This clarifies how the SL(2,C) spinfoam formalism yields an SU(2) theory on the boundary. These structures define a tidy Lorentz-covariant formalism for loop gravity.« less

Using the Gurobi Solvers on the Peregrine System | High-Performance

Science.gov Websites

Peregrine System Gurobi Optimizer is a suite of solvers for mathematical programming. It is licensed for ('GRB_MATLAB_PATH') >> path(path,grb) Gurobi and GAMS GAMS is a high-level modeling system for mathematical

the Large Aperture GRB Observatory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertou, Xavier

2009-04-30

The Large Aperture GRB Observatory (LAGO) aims at the detection of high energy photons from Gamma Ray Bursts (GRB) using the single particle technique (SPT) in ground based water Cherenkov detectors (WCD). To reach a reasonable sensitivity, high altitude mountain sites have been selected in Mexico (Sierra Negra, 4550 m a.s.l.), Bolivia (Chacaltaya, 5300 m a.s.l.) and Venezuela (Merida, 4765 m a.s.l.). We report on the project progresses and the first operation at high altitude, search for bursts in 6 months of preliminary data, as well as search for signal at ground level when satellites report a burst.

The SH2 and SH3 domains of mammalian Grb2 couple the EGF receptor to the Ras activator mSos1.

PubMed

Rozakis-Adcock, M; Fernley, R; Wade, J; Pawson, T; Bowtell, D

1993-05-06

Many tyrosine kinases, including the receptors for hormones such as epidermal growth factor (EGF), nerve growth factor and insulin, transmit intracellular signals through Ras proteins. Ligand binding to such receptors stimulates Ras guanine-nucleotide-exchange activity and increases the level of GTP-bound Ras, suggesting that these tyrosine kinases may activate a guanine-nucleotide releasing protein (GNRP). In Caenorhabditis elegans and Drosophila, genetic studies have shown that Ras activation by tyrosine kinases requires the protein Sem-5/drk, which contains a single Src-homology (SH) 2 domain and two flanking SH3 domains. Sem-5 is homologous to the mammalian protein Grb2, which binds the autophosphorylated EGF receptor and other phosphotyrosine-containing proteins such as Shc through its SH2 domain. Here we show that in rodent fibroblasts, the SH3 domains of Grb2 are bound to the proline-rich carboxy-terminal tail of mSos1, a protein homologous to Drosophila Sos. Sos is required for Ras signalling and contains a central domain related to known Ras-GNRPs. EGF stimulation induces binding of the Grb2-mSos1 complex to the autophosphorylated EGF receptor, and mSos1 phosphorylation. Grb2 therefore appears to link tyrosine kinases to a Ras-GNRP in mammalian cells.

Exploring the Cosmic Dawn, Galaxy Evolution, and Exotic Stellar Deaths with Rapid GRB Follow-Up Observations

NASA Astrophysics Data System (ADS)

Berger, Edo; Cenko, Stephen; Schmidt, Brian; Perley, Daniel; Berger, Edo; Fox, Derek; Fruchter, Andrew; Bloom, Joshua; Prochaska, Jason X.; Lopez, Sebastian; Cobb, Bethany; Roth, Kathy; Levan, Andrew; Tanvir, Nial; Rapoport, Sharon; Yuan, Fang; Chornock, Ryan; Wen-Fai, Fong; Morgan, Adam; Wiersema, Klaas; Cucchiara, Antonino

2013-08-01

The study of gamma-ray burst (GRB) afterglows, host galaxies, and associated supernovae (SNe) sheds light on a wide range of open questions in astrophysics, ranging from the deaths of massive stars to cosmic chemical enrichment and the reionization epoch, and soon, the electromagnetic (EM) counterparts of gravitational wave (GW) sources. Over the past decade, Gemini has played a leading role in all aspects of GRB science through its combination of rapid-response spectroscopy and imaging coupled with deep late-time host galaxy, afterglow, and GRB-SN follow-up. Here, we propose to step forward in our long-standing program of ToO observations, with this proposal focusing on "Rapid ToO" science, observations at t <˜ 1 day. In conjunction with an array of multi-wavelength EM facilities, we focus on three key science topics: (1) Identification, characterization, and exploitation of high-redshift GRBs in order to study the evolving IGM and galaxy populations at these redshifts; (2) Studies of short GRB afterglows and their environments to yield insight into the nature of their progenitor population, for connection with forthcoming GW facilities; and (3) Observation of exceptionally energetic bursts detected by the Fermi-LAT instrument, to test models of burst engines and enable their use as testbeds for quantum gravity effects.

Exploring the Cosmic Dawn, Galaxy Evolution, and Exotic Stellar Deaths with Rapid GRB Follow-Up Observations

NASA Astrophysics Data System (ADS)

Berger, Edo; Fox, Derek; Chornock, Ryan; Fong, Wen-Fai; Cobb, Bethany; Cenko, Brad; Perley, Daniel; Bloom, Joshua; Prochaska, Jason X.; Morgan, Adam; Cucchiara, Antonino; Levan, Andrew; Tanvir, Nial; Fruchter, Andrew; Lopez, Sebastian; Wiersema, Klaas; Roth, Kathy

2014-02-01

The study of gamma-ray burst (GRB) afterglows, host galaxies, and associated supernovae (SNe) sheds light on a wide range of open questions in astrophysics, ranging from the deaths of massive stars to cosmic chemical enrichment and the reionization epoch, and soon, the electromagnetic (EM) counterparts of gravitational wave (GW) sources. Over the past decade, Gemini has played a leading role in all aspects of GRB science through its combination of rapid-response spectroscopy and imaging coupled with deep late-time host galaxy, afterglow, and GRB-SN follow-up. Here, we propose to step forward in our long-standing program of ToO observations, with this proposal focusing on "Rapid ToO" science, observations at t <˜ 1 day. In conjunction with an array of multi-wavelength EM facilities, we focus on three key science topics: (1) Identification, characterization, and exploitation of high-redshift GRBs in order to study the evolving IGM and galaxy populations at these redshifts; (2) Studies of short GRB afterglows and their environments to yield insight into the nature of their progenitor population, for connection with forthcoming GW facilities; and (3) Observation of exceptionally energetic bursts detected by the Fermi-LAT instrument, to test models of burst engines and enable their use as testbeds for quantum gravity effects.

GRB 060505: A Possible Short-Duration Gamma-Ray Burst in a Star Forming Region at Redshift of 0.09

NASA Technical Reports Server (NTRS)

Ofek, E. O.; Cenko, S. B.; Gal-Yam, A.; Fox, D. B.; Nakar, E.; Rau, A.; Frail, D. A.; Kullkarni, S. R.; Price, P. A.; Schmidt, B. P.;

On the Afterglow and Progenitor of FRB 150418

NASA Astrophysics Data System (ADS)

Zhang, Bing

2016-05-01

Keane et al. recently detected a fading radio source following FRB 150418, leading to the identification of a putative host galaxy at z = 0.492 ± 0.008. Assuming that the fading source is the afterglow of FRB 150418, I model the afterglow and constrain the isotropic energy of the explosion to be a few 1050 erg, comparable to that of a short-duration gamma-ray burst (GRB). The outflow may have a jet opening angle of ˜0.22 rad, so that the beaming-corrected energy is below 1049 erg. The results rule out most fast radio burst (FRB) progenitor models for this FRB, but may be consistent with either of the following two scenarios. The first scenario invokes a merger of an NS-NS binary, which produced an undetected short GRB and a supra-massive neutron star, which subsequently collapsed into a black hole, probably hundreds of seconds after the short GRB. The second scenario invokes a merger of a compact star binary (BH-BH, NS-NS, or BH-NS) system whose pre-merger dynamical magnetospheric activities made the FRB, which is followed by an undetected short GRB-like transient. The gravitational-wave (GW) event GW 150914 would be a sister of FRB 150418 in this second scenario. In both cases, one expects an exciting prospect of GW/FRB/GRB associations.

Photospheric Emission in the Joint GBM and Konus Prompt Spectra of GRB 120323A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guiriec, S.; Kouveliotou, C.; Gehrels, N.

GRB 120323A is a very intense short gamma -ray burst (GRB) detected simultaneously during its prompt γ -ray emission phase with the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope and the Konus experiment on board the Wind satellite. GBM and Konus operate in the keV–MeV regime; however, the GBM range is broader toward both the low and the high parts of the γ -ray spectrum. Analyses of such bright events provide a unique opportunity to check the consistency of the data analysis as well as cross-calibrate the two instruments. We performed time-integrated and coarse time-resolved spectralmore » analysis of GRB 120323A prompt emission. We conclude that the analyses of GBM and Konus data are only consistent when using a double-hump spectral shape for both data sets; in contrast, the single hump of the empirical Band function, traditionally used to fit GRB prompt emission spectra, leads to significant discrepancies between GBM and Konus analysis results. Our two-hump model is a combination of a thermal-like and a non-thermal component. We interpret the first component as a natural manifestation of the jet photospheric emission.« less

Radio afterglow rebrightening: evidence for multiple active phases in gamma-ray burst central engines

NASA Astrophysics Data System (ADS)

Li, Long-Biao; Zhang, Zhi-Bin; Rice, Jared

2015-09-01

The rebrightening phenomenon is an interesting feature in some X-ray, optical, and radio afterglows of gamma-ray bursts (GRBs). Here, we propose a possible energy-supply assumption to explain the rebrightenings of radio afterglows, in which the central engine with multiple active phases can supply at least two GRB pulses in a typical GRB duration time. Considering the case of double pulses supplied by the central engine, the double pulses have separate physical parameters, except for the number density of the surrounding interstellar medium (ISM). Their independent radio afterglows are integrated by the ground detectors to form the rebrightening phenomenon. In this Letter, we firstly simulate diverse rebrightening light curves under consideration of different and independent physical parameters. Using this assumption, we also give our best fit to the radio afterglow of GRB 970508 at three frequencies of 1.43, 4.86, and 8.46 GHz. We suggest that the central engine may be active continuously at a timescale longer than that of a typical GRB duration time as many authors have suggested (e.g., Zhang et al., Astrophys. J. 787:66, 2014; Gao and Mészáros, Astrophys. J. 802:90, 2015), and that it may supply enough energy to cause the long-lasting rebrightenings observed in some GRB afterglows.

Constraining Lorentz Violation in Electroweak Physics

NASA Astrophysics Data System (ADS)

Lehnert, Ralf

2018-01-01

For practical reasons, the majority of past Lorentz tests has involved stable or quasistable particles, such as photons, neutrinos, electrons, protons, and neutrons. Similar efforts in the electroweak sector have only recently taken shape. Within this context, Lorentz-violation searches in the Standard-Model Extension’s Z-Boson sector will be discussed. It is argued that existing precision data on polarized electron-electron scattering can be employed to extract the first conservative two-sided limits on Lorentz breakdown in this sector at the level of 10-7.

Lorentz-violating gravitoelectromagnetism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bailey, Quentin G.

2010-09-15

The well-known analogy between a special limit of general relativity and electromagnetism is explored in the context of the Lorentz-violating standard-model extension. An analogy is developed for the minimal standard-model extension that connects a limit of the CPT-even component of the electromagnetic sector to the gravitational sector. We show that components of the post-Newtonian metric can be directly obtained from solutions to the electromagnetic sector. The method is illustrated with specific examples including static and rotating sources. Some unconventional effects that arise for Lorentz-violating electrostatics and magnetostatics have an analog in Lorentz-violating post-Newtonian gravity. In particular, we show that evenmore » for static sources, gravitomagnetic fields arise in the presence of Lorentz violation.« less

Lorentz violation and deep inelastic scattering

DOE PAGES

Kostelecký, V. Alan; Lunghi, E.; Vieira, A. R.

2017-03-28

We study the effects of quark-sector Lorentz violation on deep inelastic electron–proton scattering. Here, we show that existing data can be used to establish first constraints on numerous coefficients for Lorentz violation in the quark sector at an estimated sensitivity of parts in a million.

Superconducting-Gravimeter Tests of Local Lorentz Invariance

NASA Astrophysics Data System (ADS)

Flowers, Natasha A.; Goodge, Casey; Tasson, Jay D.

2017-11-01

Superconducting-gravimeter measurements are used to test the local Lorentz invariance of the gravitational interaction and of matter-gravity couplings. The best laboratory sensitivities to date are achieved via a maximum-reach analysis for 13 Lorentz-violating operators, with some improvements exceeding an order of magnitude.

Superconducting-Gravimeter Tests of Local Lorentz Invariance.

PubMed

Flowers, Natasha A; Goodge, Casey; Tasson, Jay D

2017-11-17

Superconducting-gravimeter measurements are used to test the local Lorentz invariance of the gravitational interaction and of matter-gravity couplings. The best laboratory sensitivities to date are achieved via a maximum-reach analysis for 13 Lorentz-violating operators, with some improvements exceeding an order of magnitude.

The SEDs and Host Galaxies of the Dustiest GRB Afterglows

NASA Technical Reports Server (NTRS)

Kruhler, T.; Greiner, J.; Schady, P.; Savaglio, S.; Afonso, P. M. J.; Clemens, C.; Elliott, J.; Filgas, R.; Gruber, D.; Kann, D. A.;

The VLT/X-shooter GRB afterglow legacy survey

NASA Astrophysics Data System (ADS)

Kaper, Lex; Fynbo, Johan P. U.; Pugliese, Vanna; van Rest, Daan

2017-11-01

The Swift satellite allows us to use gamma-ray bursts (GRBs) to peer through the hearts of star forming galaxies through cosmic time. Our open collaboration, representing most of the active European researchers in this field, builds a public legacy sample of GRB X-shooter spectroscopy while Swift continues to fly. To date, our spectroscopy of more than 100 GRB afterglows covers a redshift range from 0.059 to about 8 (Tanvir et al. 2009, Nature 461, 1254), with more than 20 robust afterglow-based metallicity measurements (over a redshift range from 1.7 to 5.9). With afterglow spectroscopy (throughout the electromagnetic spectrum from X-rays to the sub-mm) we can hence characterize the properties of star-forming galaxies over cosmic history in terms of redshift, metallicity, molecular content, ISM temperature, UV-flux density, etc.. These observations provide key information on the final evolution of the most massive stars collapsing into black holes, with the potential of probing the epoch of the formation of the first (very massive) stars. VLT/X-shooter (Vernet et al. 2011, A&A 536, A105) is in many ways the ideal GRB follow-up instrument and indeed GRB follow-up was one of the primary science cases behind the instrument design and implementation. Due to the wide wavelength coverage of X-shooter, in the same observation one can detect molecular H2 absorption near the atmospheric cut-off and many strong emission lines from the host galaxy in the near-infrared (e.g., Friis et al. 2015, MNRAS 451, 167). For example, we have measured a metallicity of 0.1 Z ⊙ for GRB 100219A at z = 4.67 (Thöne et al. 2013, MNRAS 428, 3590), 0.02 Z ⊙ for GRB 111008A at z = 4.99 (Sparre et al. 2014, ApJ 785, 150) and 0.05 Z ⊙ for GRB 130606A at z = 5.91 (Hartoog et al. 2015, A&A 580, 139). In the latter, the very high value of [Al/Fe]=2.40 +/- 0.78 might be due to a proton capture process and may be a signature of a previous generation of massive (perhaps even the first) stars. Reconciling the abundance patterns of GRB absorbers, other types of absorbers (in particular QSO DLAs), and old stars in the Local Group is an important long-term goal of this program (see Sparre et al. 2014, ApJ 785, 150). Metallicities are also measured from host emission lines (Krühler et al. 2015, A&A 581, A125). GRB spectroscopy also allows us to determine the dust content of their environments, both through analysis of the depletion pattern and the measurement of the associated extinction (Japelj et al. 2015, A&A 451, 2050). This way one can quantify the dust-to-metals ratio and its evolution with redshift. The detection of GRBs at z > 6 shows that GRBs have become competitive as a tool to identifying galaxies at the highest redshifts and unsurpassed in providing detailed abundance information via absorption line spectroscopy.

The Konus-Wind Catalog of Gamma-Ray Bursts with Known Redshifts. I. Bursts Detected in the Triggered Mode

NASA Astrophysics Data System (ADS)

Tsvetkova, A.; Frederiks, D.; Golenetskii, S.; Lysenko, A.; Oleynik, P.; Pal'shin, V.; Svinkin, D.; Ulanov, M.; Cline, T.; Hurley, K.; Aptekar, R.

2017-12-01

In this catalog, we present the results of a systematic study of gamma-ray bursts (GRBs) with reliable redshift estimates detected in the triggered mode of the Konus-Wind (KW) experiment during the period from 1997 February to 2016 June. The sample consists of 150 GRBs (including 12 short/hard bursts) and represents the largest set of cosmological GRBs studied to date over a broad energy band. From the temporal and spectral analyses of the sample, we provide the burst durations, the spectral lags, the results of spectral fits with two model functions, the total energy fluences, and the peak energy fluxes. Based on the GRB redshifts, which span the range 0.1≤slant z≤slant 5, we estimate the rest-frame, isotropic-equivalent energy, and peak luminosity. For 32 GRBs with reasonably constrained jet breaks, we provide the collimation-corrected values of the energetics. We consider the behavior of the rest-frame GRB parameters in the hardness-duration and hardness-intensity planes, and confirm the “Amati” and “Yonetoku” relations for Type II GRBs. The correction for the jet collimation does not improve these correlations for the KW sample. We discuss the influence of instrumental selection effects on the GRB parameter distributions and estimate the KW GRB detection horizon, which extends to z˜ 16.6, stressing the importance of GRBs as probes of the early universe. Accounting for the instrumental bias, we estimate the KW GRB luminosity evolution, luminosity and isotropic-energy functions, and the evolution of the GRB formation rate, which are in general agreement with those obtained in previous studies.

Thermal Emissions Spanning the Prompt and the Afterglow Phases of the Ultra-long GRB 130925A

NASA Astrophysics Data System (ADS)

Basak, Rupal; Rao, A. R.

2015-07-01

GRB 130925A is an ultra-long gamma-ray burst (GRB), and it shows clear evidence for thermal emission in the soft X-ray data of the Swift/X-ray Telescope (XRT; ∼0.5 keV), lasting until the X-ray afterglow phase. Due to the long duration of the GRB, the burst could be studied in hard X-rays with high-resolution focusing detectors (NuSTAR). The blackbody temperature, as measured by the Swift/XRT, shows a decreasing trend until the late phase (Piro et al.) whereas the high-energy data reveal a significant blackbody component during the late epochs at an order of magnitude higher temperature (∼5 keV) compared to contemporaneous low energy data (Bellm et al.). We resolve this apparent contradiction by demonstrating that a model with two black bodies and a power law (2BBPL) is consistent with the data right from the late prompt emission to the afterglow phase. Both blackbodies show a similar cooling behavior up to late times. We invoke a structured jet, having a fast spine and a slower sheath layer, to identify the location of these blackbodies. Independent of the physical interpretation, we propose that the 2BBPL model is a generic feature of the prompt emission of all long GRBs, and the thermal emission found in the afterglow phase of different GRBs reflects the lingering thermal component of the prompt emission with different timescales. We strengthen this proposal by pointing out a close similarity between the spectral evolutions of this GRB and GRB 090618, a source with significant wide band data during the early afterglow phase.

SWIFT OBSERVATIONS OF GAMMA-RAY BURST PULSE SHAPES: GRB PULSE SPECTRAL EVOLUTION CLARIFIED

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hakkila, Jon; Lien, Amy; Sakamoto, Takanori

Isolated Swift gamma-ray burst (GRB) pulses, like their higher-energy BATSE counterparts, emit the bulk of their pulsed emission as a hard-to-soft component that can be fitted by the Norris et al. empirical pulse model. This signal is overlaid by a fainter, three-peaked signal that can be modeled by the residual fit of Hakkila and Preece: the two fits combine to reproduce GRB pulses with distinctive three-peaked shapes. The precursor peak appears on or before the pulse rise and is often the hardest component, the central peak is the brightest, and the decay peak converts exponentially decaying emission into a long,more » soft, power-law tail. Accounting for systematic instrumental differences, the general characteristics of the fitted pulses are remarkably similar. Isolated GRB pulses are dominated by hard-to-soft evolution; this is more pronounced for asymmetric pulses than for symmetric ones. Isolated GRB pulses can also exhibit intensity tracking behaviors that, when observed, are tied to the timing of the three peaks: pulses with the largest maximum hardnesses are hardest during the precursor, those with smaller maximum hardnesses are hardest during the central peak, and all pulses can re-harden during the central peak and/or during the decay peak. Since these behaviors are essentially seen in all isolated pulses, the distinction between “hard-to-soft and “intensity-tracking” pulses really no longer applies. Additionally, the triple-peaked nature of isolated GRB pulses seems to indicate that energy is injected on three separate occasions during the pulse duration: theoretical pulse models need to account for this.« less

Detection of GRB 060927 at zeta = 5.47: Implications for the Use of Gamma-Ray Bursts as Probes of the End of the Dark Ages

NASA Technical Reports Server (NTRS)

Ruiz-Velasco, A. E.; Swan, H.; Troja, E.; Malesani, D.; Fynbo, J. P. U.; Sterling, R. L. C.; Xu, D.; Aharonian, F.; Akerlof, C.; Andersen, M. I.;

A molecular gas-rich GRB host galaxy at the peak of cosmic star formation

NASA Astrophysics Data System (ADS)

Arabsalmani, M.; Le Floc'h, E.; Dannerbauer, H.; Feruglio, C.; Daddi, E.; Ciesla, L.; Charmandaris, V.; Japelj, J.; Vergani, S. D.; Duc, P.-A.; Basa, S.; Bournaud, F.; Elbaz, D.

2018-05-01

We report the detection of the CO(3-2) emission line from the host galaxy of gamma-ray burst (GRB) 080207 at z = 2.086. This is the first detection of molecular gas in emission from a GRB host galaxy beyond redshift 1. We find this galaxy to be rich in molecular gas with a mass of 1.1 × 10^{11} M_{{\\odot }} assuming αCO = 4.36 M_{{\\odot }} (K km s^{-1} pc^2)^{-1}. The molecular gas mass fraction of the galaxy is ˜0.5, typical of star-forming galaxies (SFGs) with similar stellar masses and redshifts. With an SFR_{FIR} of 260 M_{{\\odot }} yr^{-1}, we measure a molecular gas depletion time-scale of 0.43 Gyr, near the peak of the depletion time-scale distribution of SFGs at similar redshifts. Our findings are therefore in contradiction with the proposed molecular gas deficiency in GRB host galaxies. We argue that the reported molecular gas deficiency for GRB hosts could be the artefact of improper comparisons or neglecting the effect of the typical low metallicities of GRB hosts on the CO-to-molecular-gas conversion factor. We also compare the kinematics of the CO(3-2) emission line to that of the H α emission line from the host galaxy. We find the H α emission to have contributions from two separate components, a narrow and a broad one. The narrow component matches the CO emission well in velocity space. The broad component, with a full width at half-maximum of ˜1100 km s^{-1}, is separated by +390 km s^{-1} in velocity space from the narrow component. We speculate this broad component to be associated with a powerful outflow in the host galaxy or in an interacting system.

Effect of carbamate pesticides on perforin, granzymes A-B-3/K, and granulysin in human natural killer cells.

PubMed

Li, Qing; Kobayashi, Maiko; Kawada, Tomoyuki

2015-09-01

We previously found that ziram, a carbamate pesticide, significantly reduced perforin, granzyme A (GrA), granzyme B (GrB), granzyme 3/K (Gr3/K), and granulysin (GRN) levels in NK-92MI cells, a human natural killer (NK) cell line. To investigate whether other carbamate pesticides also show similar toxicity on human NK cells, we conducted further experiments with NK-92CI cells, a human NK cell line, using a more sensitive assay. We previously confirmed that NK-92CI cells express CD56, perforin, GrA, GrB, Gr3/K, and GRN and are highly cytotoxic to K562 cells in a chromium release assay, which are more sensitive to organophosphorus pesticides and ziram than the NK-92MI cell line. NK-92CI cells were treated with ziram, thiram, maneb, or carbaryl at various concentrations for 4-24 h at 37°C in vitro. Thereafter, intracellular levels of perforin, GrA, GrB, Gr3/K, and GRN were determined by flow cytometry. It was found that all carbamate pesticides significantly reduced the intracellular levels of perforin, GrA, GrB, Gr3/K, and GRN in NK-92CI cells in a dose-dependent manner. However, the strength of the effect differed among the pesticides, and the order was thiram > ziram > maneb > carbaryl. In addition, it was also found that the degree of the reductions differed among the five proteins, with perforin more sensitive to pesticides than GRN, GrA, GrB, and Gr3/K, and the order was perforin > GRN > Gr3/K ≒ GrA ≒ GrB. © The Author(s) 2015.

The Spitzer/Swift Gamma-Ray Burst Host Galaxy Extended Legacy Survey

NASA Astrophysics Data System (ADS)

Perley, Daniel; Berger, Edo; Butler, Nathaniel; Cenko, S. Bradley; Chary, Ranga-Ram; Cucchiara, Antonino; Ellis, Richard; Fong, Wen-fai; Fruchter, Andrew; Fynbo, Johan; Gehrels, Neil; Graham, John; Greiner, Jochen; Hjorth, Jens; Hunt, Leslie; Jakobsson, Pall; Kruehler, Thomas; Laskar, Tanmoy; Le Floc'h, Emerich; Levan, Andrew; Levesque, Emily; Littlejohns, Owen; Malesani, Daniele; Michalowski, Michal; Prochaska, J. Xavier; Salvaterra, Ruben; Schulze, Steve; Schady, Patricia; Tanvir, Nial; de Ugarte Postigo, Antonio; Vergani, Susanna

2014-12-01

Long-duration gamma-ray bursts act as beacons to the sites of star-formation in the distant universe. GRBs reveal galaxies too faint and star-forming regions too dusty to characterize in detail using any other method, and provide a powerful independent constraint on the evolution of the cosmic star-formation rate density at high-redshift. However, a full understanding of the GRB phenomenon and its relation to cosmic star-formation requires connecting the observations obtained from GRBs to the properties of the galaxies hosting them. The large majority of GRBs originate at moderate to high redshift (z>1) and Spitzer has proven crucial for understanding the host population, given its unique ability to observe the rest-frame NIR and its unrivaled sensitivity and efficiency. We propose to complete a comprehensive public legacy survey of the Swift GRB host population to build on our earlier successes and push beyond the statistical limits of previous, smaller efforts. Our survey will enable a diverse range of GRB and galaxy science including: (1) to quantitatively and robustly map the connection between GRBs and cosmic star-formation to constrain the GRB progenitor and calibrate GRB rate-based measurements of the high-z cosmic star-formation rate; (2) to constrain the luminosity function of star-forming galaxies at the faint end and at high redshift; (3) to understand how the ISM properties seen in absorption in high-redshift galaxies unveiled by GRBs - metallicity, dust column, dust properties - connect to global properties of the host galaxies such as mass and age. Building on a decade of experience at both observatories, our observations will create an enduring joint Swift-Spitzer legacy sample and provide the definitive resource with which to examine all aspects of the GRB/galaxy connection for years and possibly decades to come.

The Arcminute Microkelvin Imager catalogue of gamma-ray burst afterglows at 15.7 GHz

NASA Astrophysics Data System (ADS)

Anderson, G. E.; Staley, T. D.; van der Horst, A. J.; Fender, R. P.; Rowlinson, A.; Mooley, K. P.; Broderick, J. W.; Wijers, R. A. M. J.; Rumsey, C.; Titterington, D. J.

2018-01-01

We present the Arcminute Microkelvin Imager (AMI) Large Array catalogue of 139 gamma-ray bursts (GRBs). AMI observes at a central frequency of 15.7 GHz and is equipped with a fully automated rapid-response mode, which enables the telescope to respond to high-energy transients detected by Swift. On receiving a transient alert, AMI can be on-target within 2 min, scheduling later start times if the source is below the horizon. Further AMI observations are manually scheduled for several days following the trigger. The AMI GRB programme probes the early-time (<1 d) radio properties of GRBs, and has obtained some of the earliest radio detections (GRB 130427A at 0.36 and GRB 130907A at 0.51 d post-burst). As all Swift GRBs visible to AMI are observed, this catalogue provides the first representative sample of GRB radio properties, unbiased by multiwavelength selection criteria. We report the detection of six GRB radio afterglows that were not previously detected by other radio telescopes, increasing the rate of radio detections by 50 per cent over an 18-month period. The AMI catalogue implies a Swift GRB radio detection rate of ≳ 15 per cent, down to ∼0.2 mJy beam-1. However, scaling this by the fraction of GRBs AMI would have detected in the Chandra & Frail sample (all radio-observed GRBs between 1997 and 2011), it is possible ∼ 44-56 per cent of Swift GRBs are radio bright, down to ∼0.1-0.15 mJy beam-1. This increase from the Chandra & Frail rate (∼30 per cent) is likely due to the AMI rapid-response mode, which allows observations to begin while the reverse-shock is contributing to the radio afterglow.

HIGH-ENERGY EMISSION OF GRB 130427A: EVIDENCE FOR INVERSE COMPTON RADIATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Yi-Zhong; Zhang, Fu-Wen; He, Hao-Ning

2013-10-20

A nearby superluminous burst GRB 130427A was simultaneously detected by six γ-ray space telescopes (Swift, the Fermi GLAST Burst Monitor (GBM)/Large Area Telescope, Konus-Wind, SPI-ACS/INTEGRAL, AGILE, and RHESSI) and by three RAPTOR full-sky persistent monitors. The isotropic γ-ray energy release is ∼10{sup 54} erg, rendering it the most powerful explosion among gamma-ray bursts (GRBs) with a redshift z ≤ 0.5. The emission above 100 MeV lasted about one day, and four photons are at energies greater than 40 GeV. We show that the count rate of 100 MeV-100 GeV emission may be mainly accounted for by the forward shock synchrotronmore » radiation and the inverse Compton radiation likely dominates at GeV-TeV energies. In particular, an inverse Compton radiation origin is favored for the ∼(95.3, 47.3, 41.4, 38.5, 32) GeV photons arriving at t ∼ (243, 256.3, 610.6, 3409.8, 34366.2) s after the trigger of Fermi-GBM. Interestingly, the external inverse Compton scattering of the prompt emission (the second episode, i.e., t ∼ 120-260 s) by the forward-shock-accelerated electrons is expected to produce a few γ-rays at energies above 10 GeV, while five were detected in the same time interval. A possible unified model for the prompt soft γ-ray, optical, and GeV emission of GRB 130427A, GRB 080319B, and GRB 090902B is outlined. Implications of the null detection of >1 TeV neutrinos from GRB 130427A by IceCube are discussed.« less

ePESSTO spectra and ATLAS photometry of SN2017iuk associated with GRB171205A

NASA Astrophysics Data System (ADS)

Prentice, S.; Mazzali, P.; Smartt, S. J.; Angus, C. R.; Firth, R. E.; Frohmaier, C.; Smith, M.; Barbarino, C.; Anderson, J.; Dennefeld, M.; Inserra, C.; Kankare, E.; Maguire, K.; Smartt, S. J.; Smith, K. W.; Sullivan, M.; Valenti, S.; Yaron, O.; Young, D.; Tonry, I. Manulis J.; Denneau, L.; Stalder, B.; Heinze, A.; Weiland, H.; Rest, A.; Fulton, M.; McBrien, O.

2017-12-01

ePESSTO, the extended Public ESO Spectroscopic Survey of Transient Objects, (see Smartt et al. 2015, A & A, 579, 40 http://www.pessto.org ), reports further spectral observations of SN 2017iuk, associated with GRB 171205A.

Comparative genomic analysis of the Haloferax volcanii DS2 and Halobacterium salinarium GRB contig maps reveals extensive rearrangement.

PubMed Central

St Jean, A; Charlebois, R L

1996-01-01

Anonymous probes from the genome of Halobacterium salinarium GRB and 12 gene probes were hybridized to the cosmid clones representing the chromosome and plasmids of Halobacterium salinarium GRB and Haloferax volcanii DS2. The order of and pairwise distances between 35 loci uniquely cross-hybridizing to both chromosomes were analyzed in a search for conservation. No conservation between the genomes could be detected at the 15-kbp resolution used in this study. We found distinct sets of low-copy-number repeated sequences in the chromosome and plasmids of Halobacterium salinarium GRB, indicating some degree of partitioning between these replicons. We propose alternative courses for the evolution of the haloarchaeal genome: (i) that the majority of genomic differences that exist between genera came about at the inception of this group or (ii) that the differences have accumulated over the lifetime of the lineage. The strengths and limitations of investigating these models through comparative genomic studies are discussed. PMID:8682791

GRB 020410: A Gamma-ray burst afterglow discovered by its supernova light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levan, Andrew; Nugent, Peter; Fruchter, Andrew

2004-03-19

We present the discovery and monitoring of the optical transient (OT) associated with GRB 020410. The fading OT was found by Hubble Space Telescope (HST) observations taken 28 and 65 days after burst at a position consistent with the X-ray afterglow. Subsequent re-examination of early ground based observations revealed that a faint OT was present 6 hours after burst, confirming the source association with GRB 020410. A deep non-detection after one week requires that the OT re-brightened between day 7 and day 28, and further late time HST data taken approximately 100 days after burst imply that it is verymore » red (F{sub nu} proportional to nu-2.7). We compare both the flux and color of the excess with supernova models and show that the data are best explained by the presence of a Type I b/c supernova at a redshift z approx. equal 0.5, which occurred roughly coincident with the day of GRB.« less

Instrumentation of LOTIS: Livermore Optical Transient Imaging System; a fully automated wide field of view telescope system searching for simultaneous optical counterparts of gamma ray bursts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, H.S.; Ables, E.; Barthelmy, S.D.

LOTIS is a rapidly slewing wide-field-of-view telescope which was designed and constructed to search for simultaneous gamma-ray burst (GRB) optical counterparts. This experiment requires a rapidly slewing ({lt} 10 sec), wide-field-of-view ({gt} 15{degrees}), automatic and dedicated telescope. LOTIS utilizes commercial tele-photo lenses and custom 2048 x 2048 CCD cameras to view a 17.6 x 17.6{degrees} field of view. It can point to any part of the sky within 5 sec and is fully automated. It is connected via Internet socket to the GRB coordinate distribution network which analyzes telemetry from the satellite and delivers GRB coordinate information in real-time. LOTISmore » started routine operation in Oct. 1996. In the idle time between GRB triggers, LOTIS systematically surveys the entire available sky every night for new optical transients. This paper will describe the system design and performance.« less

The Swift X-Ray Te1escope: Status and Performance

NASA Technical Reports Server (NTRS)

Burrows, David N.; Kennea, J.A.; Abbey, A.F.; Beardmore, A.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Evans, P.A.; Hill, J.E.;

Interactions between vortex tubes and magnetic-flux rings at high kinetic and magnetic Reynolds numbers

NASA Astrophysics Data System (ADS)

Kivotides, Demosthenes

2018-03-01

The interactions between vortex tubes and magnetic-flux rings in incompressible magnetohydrodynamics are investigated at high kinetic and magnetic Reynolds numbers, and over a wide range of the interaction parameter. The latter is a measure of the turnover time of the large-scale fluid motions in units of the magnetic damping time, or of the strength of the Lorentz force in units of the inertial force. The small interaction parameter results, which are related to kinematic turbulent dynamo studies, indicate the evolution of magnetic rings into flattened spirals wrapped around the vortex tubes. This process is also observed at intermediate interaction parameter values, only now the Lorentz force creates new vortical structures at the magnetic spiral edges, which have a striking solenoid vortex-line structure, and endow the flattened magnetic-spiral surfaces with a curvature. At high interaction parameter values, the decisive physical factor is Lorentz force effects. The latter create two (adjacent to the magnetic ring) vortex rings that reconnect with the vortex tube by forming an intriguing, serpentinelike, vortex-line structure, and generate, in turn, two new magnetic rings, adjacent to the initial one. In this regime, the morphologies of the vorticity and magnetic field structures are similar. The effects of these structures on kinetic and magnetic energy spectra, as well as on the direction of energy transfer between flow and magnetic fields, are also indicated.

Traces of Lorentz symmetry breaking in a hydrogen atom at ground state

NASA Astrophysics Data System (ADS)

Borges, L. H. C.; Barone, F. A.

2016-02-01

Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schrödinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector.

Hendrik Antoon Lorentz: his role in physics and society.

PubMed

Berends, Frits

2009-04-22

Hendrik Antoon Lorentz (1853-1928) was appointed in 1878 to a chair of theoretical physics at the University of Leiden, one of the first of such chairs in the world. A few years later Heike Kamerlingh Onnes became his experimental colleague, after vehement discussions in the faculty. Lorentz strongly supported Kamerlingh Onnes then, and proved subsequently to be an ideal colleague. With Lorentz's electron theory the classical theory of electromagnetism obtained its final form, at the time often called the Maxwell-Lorentz theory. In this theory the Zeeman effect could be explained: the first glimpse of the electron. The Nobel Prize followed in 1902. The Lorentz transformation, established in 1904, preceded the special theory of relativity. Later on, Lorentz played a much admired role in the debate on the new developments in physics, in particular as chairman of a series of Solvay conferences. Gradually his stature outside of physics grew, both nationally as chairman of the Zuiderzee committee and internationally as president of the International Commission on Intellectual Cooperation of the League of Nations. At his funeral the overwhelming tribute was the recognition of his unique greatness. Einstein said about him 'He meant more to me personally than anyone else I have met on my life's journey'.

Hendrik Antoon Lorentz: his role in physics and society

NASA Astrophysics Data System (ADS)

Berends, Frits

2009-04-01

Hendrik Antoon Lorentz (1853-1928) was appointed in 1878 to a chair of theoretical physics at the University of Leiden, one of the first of such chairs in the world. A few years later Heike Kamerlingh Onnes became his experimental colleague, after vehement discussions in the faculty. Lorentz strongly supported Kamerlingh Onnes then, and proved subsequently to be an ideal colleague. With Lorentz's electron theory the classical theory of electromagnetism obtained its final form, at the time often called the Maxwell-Lorentz theory. In this theory the Zeeman effect could be explained: the first glimpse of the electron. The Nobel Prize followed in 1902. The Lorentz transformation, established in 1904, preceded the special theory of relativity. Later on, Lorentz played a much admired role in the debate on the new developments in physics, in particular as chairman of a series of Solvay conferences. Gradually his stature outside of physics grew, both nationally as chairman of the Zuiderzee committee and internationally as president of the International Commission on Intellectual Cooperation of the League of Nations. At his funeral the overwhelming tribute was the recognition of his unique greatness. Einstein said about him 'He meant more to me personally than anyone else I have met on my life's journey'.

Equilibria of a charged artificial satellite subject to gravitational and Lorentz torques

NASA Astrophysics Data System (ADS)

Abdel-Aziz, Yehia A.; Shoaib, Muhammad

2014-07-01

The attitude dynamics of a rigid artificial satellite subject to a gravity gradient and Lorentz torques in a circular orbit are considered. Lorentz torque is developed on the basis of the electrodynamic effects of the Lorentz force acting on the charged satellite's surface. We assume that the satellite is moving in a Low Earth Orbit in the geomagnetic field, which is considered to be a dipole. Our model of torque due to the Lorentz force is developed for an artificial satellite with a general shape, and the nonlinear differential equations of Euler are used to describe its attitude orientation. All equilibrium positions are determined and conditions for their existence are obtained. The numerical results show that the charge q and radius ρ0 of the center of charge for the satellite provide a certain type of semi-passive control for the attitude of the satellite. The technique for this kind of control would be to increase or decrease the electrostatic screening on the satellite. The results obtained confirm that the change in charge can affect the magnitude of the Lorentz torque, which can also affect control of the satellite. Moreover, the relationship between magnitude of the Lorentz torque and inclination of the orbit is investigated.

Lorentz Atom Revisited by Solving the Abraham-Lorentz Equation of Motion

NASA Astrophysics Data System (ADS)

Bosse, Jürgen

2017-08-01

By solving the non-relativistic Abraham-Lorentz (AL) equation, I demonstrate that the AL equation of motion is not suited for treating the Lorentz atom, because a steady-state solution does not exist. The AL equation serves as a tool, however, for deducing the appropriate parameters Ω and Γ to be used with the equation of forced oscillations in modelling the Lorentz atom. The electric polarisability, which many authors "derived" from the AL equation in recent years, is shown to violate Kramers-Kronig relations rendering obsolete the extracted photon-absorption rate, for example. Fortunately, errors turn out to be small quantitatively, as long as the light frequency ω is neither too close to nor too far from the resonance frequency Ω. The polarisability and absorption cross section are derived for the Lorentz atom by purely classical reasoning and are shown to agree with the quantum mechanical calculations of the same quantities. In particular, oscillator parameters Ω and Γ deduced by treating the atom as a quantum oscillator are found to be equivalent to those derived from the classical AL equation. The instructive comparison provides a deep insight into understanding the great success of Lorentz's model that was suggested long before the advent of quantum theory.

DISCOVERY OF SMOOTHLY EVOLVING BLACKBODIES IN THE EARLY AFTERGLOW OF GRB 090618: EVIDENCE FOR A SPINE–SHEATH JET?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Basak, Rupal; Rao, A. R., E-mail: rupalb@tifr.res.in, E-mail: arrao@tifr.res.in

2015-10-20

GRB 090618 is a bright gamma-ray burst (GRB) with multiple pulses. It shows evidence of thermal emission in the initial pulses as well as in the early afterglow phase. Because high-resolution spectral data from the Swift/X-ray Telescope (XRT) are available for the early afterglow, we investigate the shape and evolution of the thermal component in this phase using data from the Swift/Burst Alert Telescope (BAT), the Swift/XRT, and the Fermi/Gamma-ray Burst Monitor detectors. An independent fit to the BAT and XRT data reveals two correlated blackbodies with monotonically decreasing temperatures. Hence, we investigated the combined data with a model consistingmore » of two blackbodies and a power law (2BBPL), a model suggested for several bright GRBs. We elicit the following interesting features of the 2BBPL model: (1) the same model is applicable from the peak of the last pulse in the prompt emission to the afterglow emission, (2) the ratio of temperatures and the fluxes of the two blackbodies remains constant throughout the observations, (3) the blackbody temperatures and fluxes show a monotonic decrease with time, with the BB fluxes dropping about a factor of two faster than that of the power-law (PL) emission, and (4) attributing the blackbody emission to photospheric emissions, we find that the photospheric radii increase very slowly with time, and the lower-temperature blackbody shows a larger emitting radius than that of the higher-temperature blackbody. We find some evidence that the underlying shape of the nonthermal emission is a cutoff power law rather than a PL. We sketch a spine–sheath jet model to explain our observations.« less

Novel Secondary Somatic Mutations in Ewing's Sarcoma and Desmoplastic Small Round Cell Tumors

PubMed Central

Janku, Filip; Ludwig, Joseph A.; Naing, Aung; Benjamin, Robert S.; Brown, Robert E.; Anderson, Pete; Kurzrock, Razelle

2014-01-01

Background Ewing's sarcoma (ES) and desmoplastic small round cell tumors (DSRCT) are small round blue cell tumors driven by an N-terminal containing EWS translocation. Very few somatic mutations have been reported in ES, and none have been identified in DSRCT. The aim of this study is to explore potential actionable mutations in ES and DSRCT. Methodology Twenty eight patients with ES or DSRCT had tumor tissue available that could be analyzed by one of the following methods: 1) Next-generation exome sequencing platform; 2) Multiplex PCR/Mass Spectroscopy; 3) Polymerase chain reaction (PCR)-based single- gene mutation screening; 4) Sanger sequencing; 5) Morphoproteomics. Principal Findings Novel somatic mutations were identified in four out of 18 patients with advanced ES and two of 10 patients with advanced DSRCT (six out of 28 (21.4%));KRAS (n = 1), PTPRD (n = 1), GRB10 (n = 2), MET (n = 2) and PIK3CA (n = 1). One patient with both PTPRD and GRB10 mutations and one with a GRB10 mutation achieved a complete remission (CR) on an Insulin like growth factor 1 receptor (IGF1R) inhibitor based treatment. One patient, who achieved a partial remission (PR) with IGF1R inhibitor treatment, but later developed resistance, demonstrated a KRAS mutation in the post-treatment resistant tumor, but not in the pre-treatment tumor suggesting that the RAF/RAS/MEK pathway was activated with progression. Conclusions We have reported several different mutations in advanced ES and DSRCT that have direct implications for molecularly-directed targeted therapy. Our technology agnostic approach provides an initial mutational roadmap used in the path towards individualized combination therapy. PMID:25119929

Significant and variable linear polarization during the prompt optical flash of GRB 160625B.

PubMed

Troja, E; Lipunov, V M; Mundell, C G; Butler, N R; Watson, A M; Kobayashi, S; Cenko, S B; Marshall, F E; Ricci, R; Fruchter, A; Wieringa, M H; Gorbovskoy, E S; Kornilov, V; Kutyrev, A; Lee, W H; Toy, V; Tyurina, N V; Budnev, N M; Buckley, D A H; González, J; Gress, O; Horesh, A; Panasyuk, M I; Prochaska, J X; Ramirez-Ruiz, E; Lopez, R Rebolo; Richer, M G; Román-Zúñiga, C; Serra-Ricart, M; Yurkov, V; Gehrels, N

2017-07-26

Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent-consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source. By contrast, optical and γ-ray observations during the prompt phase have led to discordant and often controversial results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.

Significant and variable linear polarization during the prompt optical flash of GRB 160625B.

NASA Astrophysics Data System (ADS)

Troja, E.; Lipunov, V. M.; Mundell, C. G.; Butler, N. R.; Watson, A. M.; Kobayashi, S.; Cenko, S. B.; Marshall, F. E.; Ricci, R.; Fruchter, A.; Wieringa, M. H.; Gorbovskoy, E. S.; Kornilov, V.; Kutyrev, A.; Lee, W. H.; Toy, V.; Tyurina, N. V.; Budnev, N. M.; Buckley, D. A. H.; González, J.; Gress, O.; Horesh, A.; Panasyuk, M. I.; Prochaska, J. X.; Ramirez-Ruiz, E.; Rebolo Lopez, R.; Richer, M. G.; Roman-Zuniga, C.; Serra-Ricart, M.; Yurkov, V.; Gehrels, N.

2017-07-01

Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent - consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source. By contrast, optical and γ-ray observations during the prompt phase have led to discordant and often controversial results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.

Optical and Near-Infrared Observations of SN 2013DX Associated with GRB 130702A

NASA Technical Reports Server (NTRS)

Toy, V. L.; Cenko, S. B.; Silverman, J. M.; Butler, N. R.; Cucchiara, A.; Watson, A. M.; Bersier, D.; Perley, D. A.; Margutti, R.; Bellm, E.;

A targeted LIGO-Virgo search for gravitational waves associated with gamma-ray bursts using low-threshold swift GRB triggers

NASA Astrophysics Data System (ADS)

Harstad, Emelie D.

Gamma-ray bursts (GRBs) are short, intense ashes of 0.1-1 MeV electromagnetic radiation that are routinely observed by Earth orbiting satellites. The sources of GRBs are known to be extragalactic and located at cosmological distances. Due to the extremely high isotropic equivalent energies of GRBs, which are on the order of Eiso˜1054 erg, the gamma-ray emission is believed to be collimated, making them observable only when they are directed towards Earth. The favored progenitor models of GRBs are also believed to emit gravitational waves that would be observable by the current generation of ground-based interferometric gravitational wave detectors. The LIGO (Laser Interferometer Gravitational-Wave Observatory) and Virgo instruments operated near design sensitivity and collected more than a year of triple coincident data during the S5/VSR1 science run, which spanned the two year interval between November 2005 and October 2007. During this time, GRB detections were being made by the NASA/Goddard Swift Burst Alert Telescope at a rate of approximately 0.3 per day, producing a collection of triggers that has since been used in a coincident GRB-GW burst search with data from the LIGO-Virgo interferometer network. This dissertation describes the search for gravitational waves using the times and locations of 123 below-threshold potential GRB triggers from Swift over the same time period. Although most of the below-threshold triggers are likely false alarms, there is reason to believe that some are the result of actual faintly-observed GRB events. Recent GRB observations indicate that the local rate of low-luminosity GRBs is much higher than previously believed. This result, combined with the possibility of discovering a rare nearby GRB event accompanied by gravitational waves, is what motivates this search. The analysis results indicate no evidence for gravitational waves associated with any of the below-threshold triggers. A median distance lower limit of ˜16 Mpc was derived for a typical neutron star-black hole coalescence progenitor assumption.

Wide-Field Gamma-Spectrometer BDRG: GRB Monitor On-Board the Lomonosov Mission

NASA Astrophysics Data System (ADS)

Svertilov, S. I.; Panasyuk, M. I.; Bogomolov, V. V.; Amelushkin, A. M.; Barinova, V. O.; Galkin, V. I.; Iyudin, A. F.; Kuznetsova, E. A.; Prokhorov, A. V.; Petrov, V. L.; Rozhkov, G. V.; Yashin, I. V.; Gorbovskoy, E. S.; Lipunov, V. M.; Park, I. H.; Jeong, S.; Kim, M. B.

2018-02-01

The study of GRB prompt emissions (PE) is one of the main goals of the Lomonosov space mission. The payloads of the GRB monitor (BDRG) with the wide-field optical cameras (SHOK) and the ultra-fast flash observatory (UFFO) onboard the Lomonosov satellite are intended for the observation of GRBs, and in particular, their prompt emissions. The BDRG gamma-ray spectrometer is designed to obtain the temporal and spectral information of GRBs in the energy range of 10-3000 keV as well as to provide GRB triggers on several time scales (10 ms, 1 s and 20 s) for ground and space telescopes, including the UFFO and SHOK. The BDRG instrument consists of three identical detector boxes with axes shifted by 90° from each other. This configuration allows us to localize a GRB source in the sky with an accuracy of ˜ 2°. Each BDRG box contains a phoswich NaI(Tl)/CsI(Tl) scintillator detector. A thick CsI(Tl) crystal in size of \\varnothing 130 × 17 mm is placed underneath the NaI(Tl) as an active shield in the soft energy range and as the main detector in the hard energy range. The ratio of the CsI(Tl) to NaI(Tl) event rates at varying energies can be employed as an independent metric to distinguish legitimate GRB signals from false positives originating from electrons in near-Earth vicinities. The data from three detectors are collected in a BA BDRG information unit, which generates a GRB trigger and a set of data frames in output format. The scientific data output is ˜ 500 Mb per day, including ˜ 180 Mb of continuous data for events with durations in excess of 100 ms for 16 channels in each detector, detailed energy spectra, and sets of frames with ˜ 5 Mb of detailed information for each burst-like event. A number of pre-flight tests including those for the trigger algorithm and calibration were carried out to confirm the reliability of the BDRG for operation in space.

GAMMA-RAY BURST HOST GALAXY SURVEYS AT REDSHIFT z {approx}> 4: PROBES OF STAR FORMATION RATE AND COSMIC REIONIZATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trenti, Michele; Perna, Rosalba; Levesque, Emily M.

2012-04-20

Measuring the star formation rate (SFR) at high redshift is crucial for understanding cosmic reionization and galaxy formation. Two common complementary approaches are Lyman break galaxy (LBG) surveys for large samples and gamma-ray burst (GRB) observations for sensitivity to SFR in small galaxies. The z {approx}> 4 GRB-inferred SFR is higher than the LBG rate, but this difference is difficult to understand, as both methods rely on several modeling assumptions. Using a physically motivated galaxy luminosity function model, with star formation in dark matter halos with virial temperature T{sub vir} {approx}> 2 Multiplication-Sign 10{sup 4} K (M{sub DM} {approx}> 2more » Multiplication-Sign 10{sup 8} M{sub Sun }), we show that GRB- and LBG-derived SFRs are consistent if GRBs extend to faint galaxies (M{sub AB} {approx}< -11). To test star formation below the detection limit L{sub lim} {approx} 0.05L*{sub z=3} of LBG surveys, we propose to measure the fraction f{sub det}(L > L{sub lim}, z) of GRB hosts with L > L{sub lim}. This fraction quantifies the missing star formation fraction in LBG surveys, constraining the mass-suppression scale for galaxy formation, with weak dependence on modeling assumptions. Because f{sub det}(L > L{sub lim}, z) corresponds to the ratio of SFRs derived from LBG and GRB surveys, if these estimators are unbiased, measuring f{sub det}(L > L{sub lim}, z) also constrains the redshift evolution of the GRB production rate per unit mass of star formation. Our analysis predicts significant success for GRB host detections at z {approx} 5 with f{sub det}(L > L{sub lim}, z) {approx} 0.4, but rarer detections at z > 6. By analyzing the upper limits on host galaxy luminosities of six z > 5 GRBs from literature data, we infer that galaxies with M{sub AB} > -15 were present at z > 5 at 95% confidence, demonstrating the key role played by very faint galaxies during reionization.« less

Neutrino-heated winds from rotating protomagnetars

NASA Astrophysics Data System (ADS)

Vlasov, Andrey D.; Metzger, Brian D.; Thompson, Todd A.

2014-11-01

We calculate the steady-state properties of neutrino-driven winds from strongly magnetized, rotating protoneutron stars (PNSs; `protomagnetars') under the assumption that the outflow geometry is set by the force-free magnetic field of an aligned dipole. Our goal is to assess protomagnetars as sites of r-process nucleosynthesis and gamma-ray burst engines using a more realistic outflow geometry than assumed in previous works. One-dimensional solutions calculated along flux tubes corresponding to different polar field lines are stitched together to determine the global properties of the flow at a given neutrino luminosity and rotation period. Protomagnetars with rotation periods of P ˜ 2-5 ms are shown to produce outflows more favourable for the production of third-peak r-process nuclei due to their much shorter expansion times through the seed nucleus formation region, yet only moderately lower entropies, as compared to normal spherical PNS winds. Protomagnetars with moderately rapid birth periods P ˜ 3-5 ms may thus represent a promising galactic r-process site which is compatible with a variety of other observations, including the recent discovery of possible magnetar-powered supernovae in metal-poor galaxies. We also confirm previous results that the outflows from protomagnetars with P ˜ 1-2 ms can achieve maximum Lorentz factors Γmax ˜ 100-1000 in the range necessary to power gamma-ray bursts (GRBs). The implications of GRB jets with a heavy nuclei-dominated composition as sources of ultrahigh energy cosmic rays are also addressed.

VizieR Online Data Catalog: GRB 120327A afterglow colour variations (Melandri+, 2017)

NASA Astrophysics Data System (ADS)

Melandri, A.; Covino, S.; Zaninoni, E.; Campana, S.; Bolmer, J.; Cobb, B. E.; Gorosabel, J.; Kim, J.-W.; Kuin, P.; Kuroda, D.; Malesani, D.; Mundell, C. G.; Nappo, F.; Sbarufatti, B.; Smith, R. J.; Steele, I. A.; Topinka, M.; Trotter, A. S.; Virgili, F. J.; Bernardini, M. G.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Ghirlanda, G.; Gomboc, A.; Greiner, J.; Guidorzi, C.; Haislip, J. B.; Hanayama, H.; Hanlon, L.; Im, M.; Ivarsen, K. M.; Japelj, J.; Jelinek, M.; Kawai, N.; Kobayashi, S.; Kopac, D.; Lacluyze, A. P.; Martin-Carrillo, A.; Murphy, D.; Reichart, D. E.; Salvaterra, R.; Salafia, O. S.; Tagliaferri, G.; Vergani, S. D.

2017-09-01

Photometric data of GRB120327A are presented. Magnitudes are in the Vega system unless for griz filters that are in the AB system, and they are all not corrected for Galactic absorption. Errors are at 1sigma level. (1 data file).

SN 2010ay is a Luminous and Broad-lined Type Ic Supernova within a Low-metallicity Host Galaxy

NASA Technical Reports Server (NTRS)

Sanders, N. E.; Soderberg, A. M.; Valenti, S.; Chomiuk, L.; Berger, E.; Smartt, S.; Hurley, K.; Barthelmy, S. D.; Chornock, R.; Foley, R. J.;

Prompt Neutrino Emission of Gamma-ray Bursts in the Dissipative Photospheric Scenario Revisited: Possible Contributions from Cocoons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiao, Di; Dai, Zi-Gao; Mészáros, Peter, E-mail: dzg@nju.edu.cn

2017-07-01

High-energy neutrinos are expected to originate from different stages in a gamma-ray burst (GRB) event. In this work, we revisit the dissipative photospheric scenario, in which the GRB prompt emission is produced around the photospheric radius. Meanwhile, possible dissipation mechanisms (e.g., internal shocks or magnetic reconnection) could accelerate cosmic-rays (CRs) to ultra-high energies and then produce neutrinos via hadronuclear and photohadronic processes, which are referred to as prompt neutrinos . In this paper, we obtain the prompt neutrino spectrum of a single GRB within a self-consistent analytical framework, in which the jet-cocoon structure and possible collimation effects are included. Wemore » investigate a possible neutrino signal from the cocoon, which has been ignored in the previous studies. We show that if a GRB event happens at a distance of the order of Mpc, there is a great chance to observe the neutrino emission from the cocoon by IceCube, which is even more promising than jet neutrinos, as the opening angle of the cocoon is much larger. We also determine the diffuse neutrino flux of GRB cocoons and find that it could be comparable with that of the jets. Our results are consistent with the latest result reported by the IceCube collaboration that no significant correlation between neutrino events and observed GRBs is seen in the new data.« less

A Collapsar Model with Disk Wind: Implications for Supernovae Associated with Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Hayakawa, Tomoyasu; Maeda, Keiichi

2018-02-01

We construct a simple but self-consistent collapsar model for gamma-ray bursts (GRBs) and SNe associated with GRBs (GRB-SNe). Our model includes a black hole, an accretion disk, and the envelope surrounding the central system. The evolutions of the different components are connected by the transfer of the mass and angular momentum. To address properties of the jet and the wind-driven SNe, we consider competition of the ram pressure from the infalling envelope and those from the jet and wind. The expected properties of the GRB jet and the wind-driven SN are investigated as a function of the progenitor mass and angular momentum. We find two conditions that should be satisfied if the wind-driven explosion is to explain the properties of the observed GRB-SNe: (1) the wind should be collimated at its base, and (2) it should not prevent further accretion even after the launch of the SN explosion. Under these conditions, some relations seen in the properties of the GRB-SNe could be reproduced by a sequence of different angular momentum in the progenitors. Only the model with the largest angular momentum could explain the observed (energetic) GRB-SNe, and we expect that the collapsar model can result in a wide variety of observational counterparts, mainly depending on the angular momentum of the progenitor star.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, D.; Krühler, T.; Hjorth, J.

Long-duration gamma-ray bursts (GRBs) at z < 1 are found in most cases to be accompanied by bright, broad-lined Type Ic supernovae (SNe Ic-BL). The highest-energy GRBs are mostly located at higher redshifts, where the associated SNe are hard to detect observationally. Here, we present early and late observations of the optical counterpart of the very energetic GRB 130427A. Despite its moderate redshift, z = 0.3399 ± 0.0002, GRB 130427A is at the high end of the GRB energy distribution, with an isotropic-equivalent energy release of E{sub iso} ∼ 9.6 × 10{sup 53} erg, more than an order of magnitudemore » more energetic than other GRBs with spectroscopically confirmed SNe. In our dense photometric monitoring, we detect excess flux in the host-subtracted r-band light curve, consistent with that expected from an emerging SN, ∼0.2 mag fainter than the prototypical SN 1998bw. A spectrum obtained around the time of the SN peak (16.7 days after the GRB) reveals broad undulations typical of SNe Ic-BL, confirming the presence of an SN, designated SN 2013cq. The spectral shape and early peak time are similar to those of the high expansion velocity SN 2010bh associated with GRB 100316D. Our findings demonstrate that high-energy, long-duration GRBs, commonly detected at high redshift, can also be associated with SNe Ic-BL, pointing to a common progenitor mechanism.« less

A New Search Paradigm for Correlated Neutrino Emission from Discrete GRBs using Antarctic Cherenkov Telescopes in the Swift Era

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stamatikos, Michael; Band, David L.; JCA/UMBC, Baltimore, MD 21250

2006-05-19

We describe the theoretical modeling and analysis techniques associated with a preliminary search for correlated neutrino emission from GRB980703a, which triggered the Burst and Transient Source Experiment (BATSE GRB trigger 6891), using archived data from the Antarctic Muon and Neutrino Detector Array (AMANDA-B10). Under the assumption of associated hadronic acceleration, the expected observed neutrino energy flux is directly derived, based upon confronting the fireball phenomenology with the discrete set of observed electromagnetic parameters of GRB980703a, gleaned from ground-based and satellite observations, for four models, corrected for oscillations. Models 1 and 2, based upon spectral analysis featuring a prompt photon energymore » fit to the Band function, utilize an observed spectroscopic redshift, for isotropic and anisotropic emission geometry, respectively. Model 3 is based upon averaged burst parameters, assuming isotropic emission. Model 4 based upon a Band fit, features an estimated redshift from the lag-luminosity relation, with isotropic emission. Consistent with our AMANDA-II analysis of GRB030329, which resulted in a flux upper limit of {approx} 0.150GeV /cm2/s for model 1, we find differences in excess of an order of magnitude in the response of AMANDA-B10, among the various models for GRB980703a. Implications for future searches in the era of Swift and IceCube are discussed.« less

High resolution crystal structure of the Grb2 SH2 domain with a phosphopeptide derived from CD28.

PubMed

Higo, Kunitake; Ikura, Teikichi; Oda, Masayuki; Morii, Hisayuki; Takahashi, Jun; Abe, Ryo; Ito, Nobutoshi

2013-01-01

Src homology 2 (SH2) domains play a critical role in cellular signal transduction. They bind to peptides containing phosphotyrosine (pY) with various specificities that depend on the flanking amino-acid residues. The SH2 domain of growth-factor receptor-bound protein 2 (Grb2) specifically recognizes pY-X-N-X, whereas the SH2 domains in phosphatidylinositol 3-kinase (PI3K) recognize pY-X-X-M. Binding of the pY site in CD28 (pY-M-N-M) by PI3K and Grb2 through their SH2 domains is a key step that triggers the CD28 signal transduction for T cell activation and differentiation. In this study, we determined the crystal structure of the Grb2 SH2 domain in complex with a pY-containing peptide derived from CD28 at 1.35 Å resolution. The peptide was found to adopt a twisted U-type conformation, similar to, but distinct from type-I β-turn. In all previously reported crystal structures, the peptide bound to the Grb2 SH2 domains adopts a type-I β-turn conformation, except those with a proline residue at the pY+3 position. Molecular modeling also suggests that the same peptide bound to PI3K might adopt a very different conformation.

Neutrinos as Probes of Lorentz Invariance

DOE PAGES

Díaz, Jorge S.

2014-01-01

Neutrinos can be used to search for deviations from exact Lorentz invariance. The worldwide experimental program in neutrino physics makes these particles a remarkable tool to search for a variety of signals that could reveal minute relativity violations. This paper reviews the generic experimental signatures of the breakdown of Lorentz symmetry in the neutrino sector.

On the harmonic-type and linear-type confinement of a relativistic scalar particle yielded by Lorentz symmetry breaking effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakke, K., E-mail: kbakke@fisica.ufpb.br; Belich, H., E-mail: belichjr@gmail.com

2016-10-15

Based on the Standard Model Extension, we investigate relativistic quantum effects on a scalar particle in backgrounds of the Lorentz symmetry violation defined by a tensor field. We show that harmonic-type and linear-type confining potentials can stem from Lorentz symmetry breaking effects, and thus, relativistic bound state solutions can be achieved. We first analyse a possible scenario of the violation of the Lorentz symmetry that gives rise to a harmonic-type potential. In the following, we analyse another possible scenario of the breaking of the Lorentz symmetry that induces both harmonic-type and linear-type confining potentials. In this second case, we alsomore » show that not all values of the parameter associated with the intensity of the electric field are permitted in the search for polynomial solutions to the radial equation, where the possible values of this parameter are determined by the quantum numbers of the system and the parameters associated with the violation of the Lorentz symmetry.« less

Alternative theories of gravity and Lorentz violation

NASA Astrophysics Data System (ADS)

Xu, Rui; Foster, Joshua; Kostelecky, V. Alan

2017-01-01

General relativity has achieved many successes, including the prediction of experimental results. However, its incompatibility with quantum theory remains an obstacle. By extending the foundational properties of general relativity, alternative theories of gravity can be constructed. In this talk, we focus on fermion couplings in the weak-gravity limit of certain alternative theories of gravity. Under suitable experimental circumstances, some of these couplings match terms appearing in the gravitational SME, which is a general framework describing violations of local Lorentz invariance. Existing limits on Lorentz violation can therefore be used to constrain certain Lorentz-invariant alternative theories of gravity.

Lorentz violation and gravity

NASA Astrophysics Data System (ADS)

Bailey, Quentin G.

2007-08-01

This work explores the theoretical and experimental aspects of Lorentz violation in gravity. A set of modified Einstein field equations is derived from the general Lorentz-violating Standard-Model Extension (SME). Some general theoretical implications of these results are discussed. The experimental consequences for weak-field gravitating systems are explored in the Earth- laboratory setting, the solar system, and beyond. The role of spontaneous Lorentz-symmetry breaking is discussed in the context of the pure-gravity sector of the SME. To establish the low-energy effective Einstein field equations, it is necessary to take into account the dynamics of 20 coefficients for Lorentz violation. As an example, the results are compared with bumblebee models, which are general theories of vector fields with spontaneous Lorentz violation. The field equations are evaluated in the post- newtonian limit using a perfect fluid description of matter. The post-newtonian metric of the SME is derived and compared with some standard test models of gravity. The possible signals for Lorentz violation due to gravity-sector coefficients are studied. Several new effects are identified that have experimental implications for current and future tests. Among the unconventional effects are a new type of spin precession for a gyroscope in orbit and a modification to the local gravitational acceleration on the Earth's surface. These and other tests are expected to yield interesting sensitivities to dimensionless gravity- sector coefficients.

30 years of Gamma Ray Bursts and the Transient High Energy Sky

NASA Technical Reports Server (NTRS)

Kouveliotou, Chryssa

2009-01-01

The first GRB was discovered on 1967, just over 40 years ago. It took several years and multiple generations of space and ground instruments to unravel some of the mysteries of this phenomenon. However, many questions remain open today. I will discuss the history, evolution and current status of the GRB field and its contributions in our understanding of the transient high energy sky. Further, I will discuss my involvement with the discovery of magnetars, neutron stars with extreme magnetic fields, serendipitously detected by GRB observers on 1979. Finally, I will describe how GRBs can be utilized in future missions as tools, to probe the cosmic chemical evolution of the Universe.

A new software on TUG-T60 autonomous telescope for astronomical transient events

NASA Astrophysics Data System (ADS)

Dindar, Murat; Helhel, Selçuk; Esenoğlu, Hasan; Parmaksızoğlu, Murat

2015-03-01

Robotic telescopes usually run under the control of a scheduler, which provides high-level control by selecting astronomical targets for observation. TÜBİTAK (Scientific and Technological Research Council of Turkey) National Observatory (TUG)-T60 Robotic Telescope is controlled by open-source OCAAS software, formally named Talon. This study introduces new software which was designed for Talon to catch GRB, GAIA and transient alerts. The new GRB software module (daemon process) alertd is running with all other modules of Talon such as telescoped; focus, dome; camerad and telrun. Maximum slew velocity and acceleration limits of the T60 telescope are enough fast for the GRB and transient observations.

X-Ray and Multi-Wavelength Observations of Gamma Ray Bursts (GRBs)

NASA Technical Reports Server (NTRS)

Kouveliotou, Chryssa

2009-01-01

The launch of the Italian (with Dutch participation) satellite BeppoSAX in 1996 enabled the detection of the first X-ray GRB afterglow, which in turn led to GRB counterpart detection in multiple wavelengths. This breakthrough firmly established the cosmological nature of GRBs. However, afterglow observations of GRBs took off in large numbers after the launch of NASA's Swift satellite in 2004. Swift enabled multiple major discoveries, such as the early lightcurves of X-ray afterglows, the first detection of a short GRB afterglow and opened more questions such as where are the elusive breaks in afterglow light curves. I will describe here these results and will discuss future opportunities and improvements in the field.

The optical rebrightening of GRB100814A: an interplay of forward and reverse shocks?

NASA Astrophysics Data System (ADS)

De Pasquale, Massimiliano; Kuin, N. P. M.; Oates, S.; Schulze, S.; Cano, Z.; Guidorzi, C.; Beardmore, A.; Evans, P. A.; Uhm, Z. L.; Zhang, B.; Page, M.; Kobayashi, S.; Castro-Tirado, A.; Gorosabel, J.; Sakamoto, T.; Fatkhullin, T.; Pandey, S. B.; Im, M.; Chandra, P.; Frail, D.; Gao, H.; Kopač, D.; Jeon, Y.; Akerlof, C.; Huang, K. Y.; Pak, S.; Park, W.-K.; Gomboc, A.; Melandri, A.; Zane, S.; Mundell, C. G.; Saxton, C. J.; Holland, S. T.; Virgili, F.; Urata, Y.; Steele, I.; Bersier, D.; Tanvir, N.; Sokolov, V. V.; Moskvitin, A. S.

2015-05-01

We present a wide data set of gamma-ray, X-ray, UV/Opt/IR (UVOIR), and radio observations of the Swift GRB100814A. At the end of the slow decline phase of the X-ray and optical afterglow, this burst shows a sudden and prominent rebrightening in the optical band only, followed by a fast decay in both bands. The optical rebrightening also shows chromatic evolution. Such a puzzling behaviour cannot be explained by a single component model. We discuss other possible interpretations, and we find that a model that incorporates a long-lived reverse shock and forward shock fits the temporal and spectral properties of GRB100814 the best.

Properties of TEM standing waves with E||B

NASA Astrophysics Data System (ADS)

Zaghloul, H.; Buckmaster, H. A.

This paper summarizes the known properties of E∥B TEM standing waves and shows that for such waves (i) E and B cannot be linearly polarized, (ii) E ≠ αB where α is a constant (iii) it is impossible to find a Lorentz frame where E>B, (iv) direction of the propagation vector cannot be inferred from the fields at one point of the space, (v) their behaviour under Lorentz, parity, time-reversal and gauge transformations is proper, (vi) both Lorentz invariants E2 - B2 and E·B are nonzero, (vii) the magnetic helicity may be nonzero, (viii) the magnetic field may be force-free, and (ix) kμFμv ≠ 0. It also shows how electromagnetic waves can be classified using Lorentz invariants. Cet article résume les qualités connues des ondes stationnaires E∥B TEM et montre que pour des ondes parallèles (i) E et B ne peuvent pas être polarisées linéairement, (ii) E ≠ αB où a est une constante, (iii) il est impossible de trouver une construction de Lorentz où E>B, (iv) la direction de propagation d'un vecteur ne peut pas être déduite des opérations à un point d'intervalle, (v) leur conduite sous Lorentz, parité, temps inverse et transformations de jauge est propre, (vi) les deux invariants de Lorentz E2 - B2 et E·B sont non nulles (vii) l'hélice magnétique peut être non nulle (viii) l'opération magnétique peut être de force libre et (ix) KμFμ v ≠ 0. Ceci montre aussi comment les ondes électromagnétiques peuvent être classifiées, en employant les invariants de Lorentz.

Low-energy Lorentz violation from high-energy modified dispersion in inertial and circular motion

NASA Astrophysics Data System (ADS)

Louko, Jorma; Upton, Samuel D.

2018-01-01

We consider an Unruh-DeWitt detector in inertial and circular motion in Minkowski spacetime of arbitrary dimension, coupled to a quantized scalar field with the Lorentz-violating dispersion relation ω =|k |f (|k |/M⋆) , where M⋆ is the Lorentz-breaking scale. Assuming that f dips below unity somewhere, we show that an inertial detector experiences large low-energy Lorentz violations in all spacetime dimensions greater than two, generalizing previous results in four dimensions. For a detector in circular motion, we show that a similar low-energy Lorentz violation occurs in three spacetime dimensions, and we lay the analytic groundwork for examining circular motion in all dimensions greater than three, generalizing previous work by Stargen, Kajuri and Sriramkumar in four dimensions. The circular motion results may be relevant for the prospects of observing the circular motion Unruh effect in analogue laboratory systems.

Effect of bulk Lorentz violation on anisotropic brane cosmologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heydari-Fard, Malihe, E-mail: heydarifard@qom.ac.ir

2012-04-01

The effect of Lorentz invariance violation in cosmology has attracted a considerable amount of attention. By using a dynamical vector field assumed to point in the bulk direction, with Lorentz invariance holding on the brane, we extend the notation of Lorentz violation in four dimensions Jacobson to a five-dimensional brane-world. We obtain the general solution of the field equations in an exact parametric form for Bianchi type I space-time, with perfect fluid as a matter source. We show that the brane universe evolves from an isotropic/anisotropic state to an isotropic de Sitter inflationary phase at late time. The early timemore » behavior of anisotropic brane universe is largely dependent on the Lorentz violating parameters β{sub i},i = 1,2,3 and the equation of state of the matter, while its late time behavior is independent of these parameters.« less

Derivation of the Lorentz force law, the magnetic field concept and the Faraday Lenz and magnetic Gauss laws using an invariant formulation of the Lorentz transformation

NASA Astrophysics Data System (ADS)

Field, J. H.

2006-06-01

It is demonstrated how the right-hand sides of the Lorentz transformation equations may be written, in a Lorentz-invariant manner, as 4-vector scalar products. This implies the existence of invariant length intervals analogous to invariant proper time intervals. An important distinction between the physical meanings of the space time and energy momentum 4-vectors is pointed out. The formalism is shown to provide a short derivation of the Lorentz force law of classical electrodynamics, and the conventional definition of the magnetic field, in terms of spatial derivatives of the 4-vector potential, as well as the Faraday Lenz law and the Gauss law for magnetic fields. The connection between the Gauss law for the electric field and the electrodynamic Ampère law, due to the 4-vector character of the electromagnetic potential, is also pointed out.

Astronomy in Denver: Spectropolarimetric Observations of 5 Wolf-Rayet Binary Stars with SALT/RSS

NASA Astrophysics Data System (ADS)

Fullard, Andrew; Ansary, Zyed; Azancot Luchtan, Daniel; Gallegos, Hunter; Luepker, Martin; Hoffman, Jennifer L.; Nordsieck, Kenneth H.; SALT observation team

2018-06-01

Mass loss from massive stars is an important yet poorly understood factor in shaping their evolution. Wolf-Rayet (WR) stars are of particular interest due to their stellar winds, which create large regions of circumstellar material (CSM). They are also supernova and possible gamma-ray burst (GRB) progenitors. Like other massive stars, WR stars often occur in binaries, where interaction can affect their mass loss rates and provide the rapid rotation thought to be required for GRB production. The diagnostic tool of spectropolarimetry, along with the potentially eclipsing nature of a binary system, helps us to better characterize the CSM created by the stars’ colliding winds. Thus, we can determine mass loss rates and infer rapid rotation. We present spectropolarimetric results for five WR+O eclipsing binary systems, obtained with the Robert Stobie Spectrograph at the South African Large Telescope, between April 2017 and April 2018. The data allow us to map both continuum and emission line polarization variations with phase, which constrains where different CSM components scatter light in the systems. We discuss our initial findings and interpretations of the polarimetric variability in each binary system, and compare the systems.

M. tuberculosis-Initiated Human Mannose Receptor Signaling Regulates Macrophage Recognition and Vesicle Trafficking by FcRγ-Chain, Grb2, and SHP-1.

PubMed

Rajaram, Murugesan V S; Arnett, Eusondia; Azad, Abul K; Guirado, Evelyn; Ni, Bin; Gerberick, Abigail D; He, Li-Zhen; Keler, Tibor; Thomas, Lawrence J; Lafuse, William P; Schlesinger, Larry S

2017-10-03

Despite its prominent role as a C-type lectin (CTL) pattern recognition receptor, mannose receptor (MR, CD206)-specific signaling molecules and pathways are unknown. The MR is highly expressed on human macrophages, regulating endocytosis, phagocytosis, and immune responses and mediating Mycobacterium tuberculosis (M.tb) phagocytosis by human macrophages, thereby limiting phagosome-lysosome (P-L) fusion. We identified human MR-associated proteins using phosphorylated and non-phosphorylated MR cytoplasmic tail peptides. We found that MR binds FcRγ-chain, which is required for MR plasma membrane localization and M.tb cell association. Additionally, we discovered that MR-mediated M.tb association triggers immediate MR tyrosine residue phosphorylation and Grb2 recruitment, activating the Rac/Pak/Cdc-42 signaling cascade important for M.tb uptake. MR activation subsequently recruits SHP-1 to the M.tb-containing phagosome, where its activity limits PI(3)P generation at the phagosome and M.tb P-L fusion and promotes M.tb growth. In sum, we identify human MR signaling pathways that temporally regulate phagocytosis and P-L fusion during M.tb infection. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

GRB 091127: The cooling break race on magnetic fuel

NASA Astrophysics Data System (ADS)

Filgas, R.; Greiner, J.; Schady, P.; Krühler, T.; Updike, A. C.; Klose, S.; Nardini, M.; Kann, D. A.; Rossi, A.; Sudilovsky, V.; Afonso, P. M. J.; Clemens, C.; Elliott, J.; Nicuesa Guelbenzu, A.; Olivares E., F.; Rau, A.

2011-11-01

Aims: Using high-quality, broad-band afterglow data for GRB 091127, we investigate the validity of the synchrotron fireball model for gamma-ray bursts (GRBs), and infer physical parameters of the ultra-relativistic outflow. Methods: We used multi-wavelength (NIR to X-ray) follow-up observations obtained with GROND simultaneously in the g'r'i'z'JH filters and the XRT onboard the Swift satellite in the 0.3 to 10 keV energy range. The resulting afterglow light curve is of excellent accuracy with relative photometric errors as low as 1%, and the spectral energy distribution (SED) is well-sampled over 5 decades in energy. These data present one of the most comprehensive observing campaigns for a single GRB afterglow and allow us to test several proposed emission models and outflow characteristics in unprecedented detail. Results: Both the multi-color light curve and the broad-band SED of the afterglow of GRB 091127 show evidence of a cooling break moving from high to lower energies. The early light curve is well described by a broken power-law, where the initial decay in the optical/NIR wavelength range is considerably flatter than at X-rays. Detailed fitting of the time-resolved SED shows that the break is very smooth with a sharpness index of 2.2 ± 0.2, and evolves towards lower frequencies as a power-law with index - 1.23 ± 0.06. These are the first accurate and contemporaneous measurements of both the sharpness of the spectral break and its time evolution. Conclusions: The measured evolution of the cooling break (νc ∝ t~-1.2) is not consistent with the predictions of the standard model, wherein νc ∝ t~-0.5 is expected. A possible explanation for the observed behavior is a time dependence of the microphysical parameters, in particular the fraction of the total energy in the magnetic field ɛB. This conclusion provides further evidence that the standard fireball model is too simplistic, and time-dependent micro-physical parameters may be required to model the growing number of well-sampled afterglow light curves. Tables 3 and 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A57

CFS Products

Science.gov Websites

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Swift Data Products in GCN

NASA Astrophysics Data System (ADS)

Barthelmy, Scott D.

2006-09-01

The Swift mission produces a much larger range of data products for the GRB Coordinates Distribution (GCN) system than any previous mission. Beyond the normal position-containing notices, the extra products are lightcurves, spectra, and images. We will present examples of these new data products and how they can be used to guide GRB follow-up observation campaigns.

Smooth Optical Self-similar Emission of Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Lipunov, Vladimir; Simakov, Sergey; Gorbovskoy, Evgeny; Vlasenko, Daniil

2017-08-01

We offer a new type of calibration for gamma-ray bursts (GRB), in which some class of GRB can be marked and share a common behavior. We name this behavior Smooth Optical Self-similar Emission (SOS-similar Emission) and identify this subclasses of GRBs with optical light curves described by a universal scaling function.

The optical afterglow of the short gamma-ray burst GRB 050709.

PubMed

Hjorth, Jens; Watson, Darach; Fynbo, Johan P U; Price, Paul A; Jensen, Brian L; Jørgensen, Uffe G; Kubas, Daniel; Gorosabel, Javier; Jakobsson, Páll; Sollerman, Jesper; Pedersen, Kristian; Kouveliotou, Chryssa

2005-10-06

It has long been known that there are two classes of gamma-ray bursts (GRBs), mainly distinguished by their durations. The breakthrough in our understanding of long-duration GRBs (those lasting more than approximately 2 s), which ultimately linked them with energetic type Ic supernovae, came from the discovery of their long-lived X-ray and optical 'afterglows', when precise and rapid localizations of the sources could finally be obtained. X-ray localizations have recently become available for short (duration <2 s) GRBs, which have evaded optical detection for more than 30 years. Here we report the first discovery of transient optical emission (R-band magnitude approximately 23) associated with a short burst: GRB 050709. The optical afterglow was localized with subarcsecond accuracy, and lies in the outskirts of a blue dwarf galaxy. The optical and X-ray afterglow properties 34 h after the GRB are reminiscent of the afterglows of long GRBs, which are attributable to synchrotron emission from ultrarelativistic ejecta. We did not, however, detect a supernova, as found in most nearby long GRB afterglows, which suggests a different origin for the short GRBs.

The Origin of the Optical Flashes: The Case Study of GRB 080319B and GRB 130427A

NASA Astrophysics Data System (ADS)

Fraija, N.; Veres, P.

2018-05-01

Correlations between optical flashes and gamma-ray emissions in gamma-ray bursts (GRBs) have been searched in order to clarify the question of whether these emissions occur at internal and/or external shocks. Among the most powerful GRBs ever recorded are GRB 080319B and GRB 130427A, which at early phases presented bright optical flashes possibly correlated with γ-ray components. Additionally, both bursts were fortuitously located within the field of view of the TeV γ-ray Milagro and HAWC observatories, and although no statistically significant excess of counts were collected, upper limits were placed on the GeV–TeV emission. Considering the synchrotron self-Compton emission from internal shocks and requiring the GeV–TeV upper limits, we found that the optical flashes and the γ-ray components are produced by different electron populations. Analyzing the optical flashes together with the multiwavelength afterglow observation, we found that these flashes can be interpreted in the framework of the synchrotron reverse shock model when outflows have arbitrary magnetizations.

Dimer formation through domain swapping in the crystal structure of the Grb2-SH2-Ac-pYVNV complex.

PubMed

Schiering, N; Casale, E; Caccia, P; Giordano, P; Battistini, C

2000-11-07

Src homology 2 (SH2) domains are key modules in intracellular signal transduction. They link activated cell surface receptors to downstream targets by binding to phosphotyrosine-containing sequence motifs. The crystal structure of a Grb2-SH2 domain-phosphopeptide complex was determined at 2.4 A resolution. The asymmetric unit contains four polypeptide chains. There is an unexpected domain swap so that individual chains do not adopt a closed SH2 fold. Instead, reorganization of the EF loop leads to an open, nonglobular fold, which associates with an equivalent partner to generate an intertwined dimer. As in previously reported crystal structures of canonical Grb2-SH2 domain-peptide complexes, each of the four hybrid SH2 domains in the two domain-swapped dimers binds the phosphopeptide in a type I beta-turn conformation. This report is the first to describe domain swapping for an SH2 domain. While in vivo evidence of dimerization of Grb2 exists, our SH2 dimer is metastable and a physiological role of this new form of dimer formation remains to be demonstrated.

Gamma-Ray Burst Spectral Indices: Evidence for Deceleration of Synchrotron Shocks

NASA Technical Reports Server (NTRS)

Preece, R. D.; Briggs, M. S.; Giblin, T.; Mallozzi, R. S.; Pendleton, G. N.; Paciesas, W. S.; Band, D. L.

2000-01-01

The current scenario for gamma-ray bursts (GRBs) involves internal shocks for the prompt GRB emission phase and external shocks for the afterglow phase. Assuming synchrotron emission from energetic shocked electrons. GRB spectra observed with a low-energy power-law spectral index greater than -2/3 (for positive photon number indices E(sup alpha) indicate a problem with this model. The remaining spectra can test the synchrotron shock model prediction that the emission from a single distribution of electrons, cooling rapidly, is responsible for both the low-energy and high-energy power-low portions of the spectra. We find that the inferred relationship between the two spectral indices of observed GRB spectra is inconsistent with the constraints from the model, posing another problem for the synchrotron shock emission model. To overcome this problem, we describe a model where the average of -1, rather than the value of -3/2 predicted for cooling electrons. Situations where this might arise have been discussed in other contexts, and involve deceleration of the internal shocks during the GRB phase.

CGM-GRB: A survey of the CircumGalactic Medium around GRB hosts

NASA Astrophysics Data System (ADS)

Gatkine, Pradip; Veilleux, Sylvain; Cucchiara, Antonino; Cenko, Bradley

2018-01-01

Recent space- and ground-based studies of the circumgalactic medium around galaxies have revealed the dynamic interplay between the galaxy ecosystem and surrounding CGM using bright background quasars. Here, we extend this investigation of the CGM to higher redshifts by using the bright afterglows of gamma-ray bursts as background sources. This provides a unique opportunity to probe the host galaxy ISM and its surrounding CGM together. We compiled a sample of 25 high-resolution (R > 8000) and high-quality (typical S/N ~ 20) rest-frame UV spectra of GRB afterglows with a redshift range (1.5 < z < 5.9) obtained using Keck-HIRES, VLT-UVES, and VLT-X-shooter spectrographs. We fit multi-component Voigt profiles to several absorption lines of both high-ionization (O VI, C IV, Si IV, etc) and low-ionization species (Si II, C II, Fe II, etc) to extract the column densities (N), Doppler parameters (b) and line-centroids. The preliminary results of our analysis on the kinematics and physical properties of the ISM and CGM of these GRB hosts are presented here.

Implications for the Origin of GRB 051103 from LIGO Observations

NASA Technical Reports Server (NTRS)

Bizouard, M. A.; Dietz, A.; Guidi, G. M.; Was, M.; Camp, J. B.; Cannizzo, J.; Stroeer, A. S.; Blackburn, L.

2012-01-01

We present the results of a LIGO search for gravitational waves (GWs) associated with GRB 051103, a short-duration hard-spectrum gamma-ray burst whose electromagnetically determined sky position is coincident with the spiral galaxy M81, which is 3.6Mpc from Earth. Possible progenitors for short-hard GRBs include compact object mergers and soft gamma repeater (SGR) giant flares. A merger progenitor would produce a characteristic GW signal that should be detectable at the distance of M81, while GW emission from an SGR is not expected to be detectable at that distance. We found no evidence of a GW signal associated with GRB 051103. Assuming weakly beamed gamma-ray emission with a jet semi-angle of 30. we exclude a binary neutron star merger in M81 as the progenitor with a confidence of 98%. Neutron star-black hole mergers are excluded with > 99% confidence. If the event occurred in M81 our findings support the hypothesis that GRB 051103 was due to an SGR giant flare, making it the most distant extragalactic magnetar observed to date.

SWIFT Detects a remarkable Gamma-ray Burst, GRB 060514, that introduces a New Classification Scheme

NASA Technical Reports Server (NTRS)

Gehrels, N.; Norris, J. P.; Mangano, V.; Barthelmy, S. D.; Burrows, D. N.; Granot, J.; Kaneko, Y.; Kouveliotou, C.; Markwardt, C. B.; Meszaros, P.;

Grb2-SH3 ligand inhibits the growth of HER2+ cancer cells and has antitumor effects in human cancer xenografts alone and in combination with docetaxel.

PubMed

Gril, Brunilde; Vidal, Michel; Assayag, Franck; Poupon, Marie-France; Liu, Wang-Qing; Garbay, Christiane

2007-07-15

HER2 represents an important signaling pathway in breast and other cancers. Herceptin has demonstrated clinical activity, but resistance is common. Thus, new therapeutic approaches to the HER2 pathway are needed. Grb2 is an adaptor protein involved in Ras-dependent signaling induced by HER2 receptors. A specific Grb2-SH3 ligand, designed and synthesized in our laboratory, called peptidimer-c, inhibited colony formation in HER2 overexpressing SKBr3 cancer cells. Combined treatment of peptidimer-c with docetaxel further inhibited both colony formation and tumor cell survival compared to docetaxel treatment alone. Efficacy of this combined treatment was correlated with a reduction in the phosphorylation of MAPK and AKT. Finally, peptidimer-c reduced the growth of a HER2(+) human breast cancer (BK111) xenograft in nude mice and potentiated the antitumor effect of docetaxel in a HER2+ hormone-independent human prostate adenocarcinoma (PAC120 HID28) xenograft. These results validate Grb2 as a new target for the HER2 pathway. (c) 2007 Wiley-Liss, Inc.

Grb2-SH3 ligand inhibits the growth of HER2+ cancer cells and has antitumor effects in human cancer xenografts alone and in combination with docetaxel

PubMed Central

Gril, Brunilde; Vidal, Michel; Assayag, Franck; Poupon, Marie-France; Liu, Wang-Qing; Garbay, Christiane

2007-01-01

HER2 represents an important signaling pathway in breast and other cancers. Herceptin has demonstrated clinical activity, but resistance is common. Thus, new therapeutic approaches to the HER2 pathway are needed. Grb2 is an adaptor protein involved in Ras-dependent signaling induced by HER2 receptors. A specific Grb2-SH3 ligand, designed and synthesized in our laboratory, called peptidimer-c, inhibited colony formation in HER2 over-expressing SKBr3 cancer cells. Combined treatment of peptidimer-c with docetaxel further inhibited both colony formation and tumor cell survival compared to docetaxel treatment alone. Efficacy of this combined treatment was correlated with a reduction in the phosphorylation of MAPK and AKT. Finally, peptidimer-c reduced the growth of a HER2+ human breast cancer (BK111) xenograft in nude mice and potentiated the anti-tumor effect of docetaxel in a HER2+ hormone-independent human prostate adenocarcinoma (PAC120 HID28) xenograft. These results validate Grb2 as a new target for the HER2 pathway. PMID:17372910

UBAT of UFFO/ Lomonosov: The X-Ray Space Telescope to Observe Early Photons from Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Jeong, S.; Panasyuk, M. I.; Reglero, V.; Connell, P.; Kim, M. B.; Lee, J.; Rodrigo, J. M.; Ripa, J.; Eyles, C.; Lim, H.; Gaikov, G.; Jeong, H.; Leonov, V.; Chen, P.; Castro-Tirado, A. J.; Nam, J. W.; Svertilov, S.; Yashin, I.; Garipov, G.; Huang, M.-H. A.; Huang, J.-J.; Kim, J. E.; Liu, T.-C.; Petrov, V.; Bogomolov, V.; Budtz-Jørgensen, C.; Brandt, S.; Park, I. H.

2018-02-01

The Ultra-Fast Flash Observatory (UFFO) Burst Alert and Trigger Telescope (UBAT) has been designed and built for the localization of transient X-ray sources such as Gamma Ray Bursts (GRBs). As one of main instruments in the UFFO payload onboard the Lomonosov satellite (hereafter UFFO/ Lomonosov), the UBAT's roles are to monitor the X-ray sky, to rapidly locate and track transient sources, and to trigger the slewing of a UV/optical telescope, namely Slewing Mirror Telescope (SMT). The SMT, a pioneering application of rapid slewing mirror technology has a line of sight parallel to the UBAT, allowing us to measure the early UV/optical GRB counterpart and study the extremely early moments of GRB evolution. To detect X-rays, the UBAT utilizes a 191.1 cm2 scintillation detector composed of Yttrium Oxyorthosilicate (YSO) crystals, Multi-Anode Photomultiplier Tubes (MAPMTs), and associated electronics. To estimate a direction vector of a GRB source in its field of view, it employs the well-known coded aperture mask technique. All functions are written for implementation on a field programmable gate array to enable fast triggering and to run the device's imaging algorithms. The UFFO/ Lomonosov satellite was launched on April 28, 2016, and is now collecting GRB observation data. In this study, we describe the UBAT's design, fabrication, integration, and performance as a GRB X-ray trigger and localization telescope, both on the ground and in space.

Caenorhabditis elegans fibroblast growth factor receptor signaling can occur independently of the multi-substrate adaptor FRS2.

PubMed

Lo, Te-Wen; Bennett, Daniel C; Goodman, S Jay; Stern, Michael J

2010-06-01

The components of receptor tyrosine kinase signaling complexes help to define the specificity of the effects of their activation. The Caenorhabditis elegans fibroblast growth factor receptor (FGFR), EGL-15, regulates a number of processes, including sex myoblast (SM) migration guidance and fluid homeostasis, both of which require a Grb2/Sos/Ras cassette of signaling components. Here we show that SEM-5/Grb2 can bind directly to EGL-15 to mediate SM chemoattraction. A yeast two-hybrid screen identified SEM-5 as able to interact with the carboxy-terminal domain (CTD) of EGL-15, a domain that is specifically required for SM chemoattraction. This interaction requires the SEM-5 SH2-binding motifs present in the CTD (Y(1009) and Y(1087)), and these sites are required for the CTD role of EGL-15 in SM chemoattraction. SEM-5, but not the SEM-5 binding sites located in the CTD, is required for the fluid homeostasis function of EGL-15, indicating that SEM-5 can link to EGL-15 through an alternative mechanism. The multi-substrate adaptor protein FRS2 serves to link vertebrate FGFRs to Grb2. In C. elegans, an FRS2-like gene, rog-1, functions upstream of a Ras/MAPK pathway for oocyte maturation but is not required for EGL-15 function. Thus, unlike the vertebrate FGFRs, which require the multi-substrate adaptor FRS2 to recruit Grb2, EGL-15 can recruit SEM-5/Grb2 directly.

Groundwater Arsenic Contamination in the Ganga River Basin: A Future Health Danger

PubMed Central

Chakraborti, Dipankar; Rahman, Mohammad Mahmudur; Dutta, Rathindra Nath; Mukherjee, Subhas Chandra; Pati, Shyamapada; Kar, Probir Bijoy

2018-01-01

This study highlights the severity of arsenic contamination in the Ganga River basin (GRB), which encompasses significant geographic portions of India, Bangladesh, Nepal, and Tibet. The entire GRB experiences elevated levels of arsenic in the groundwater (up to 4730 µg/L), irrigation water (~1000 µg/L), and in food materials (up to 3947 µg/kg), all exceeding the World Health Organization’s standards for drinking water, the United Nations Food and Agricultural Organization’s standard for irrigation water (100 µg/L), and the Chinese Ministry of Health’s standard for food in South Asia (0.15 mg/kg), respectively. Several individuals demonstrated dermal, neurological, reproductive, cognitive, and cancerous effects; many children have been diagnosed with a range of arsenicosis symptoms, and numerous arsenic-induced deaths of youthful victims are reported in the GRB. Victims of arsenic exposure face critical social challenges in the form of social isolation and hatred by their respective communities. Reluctance to establish arsenic standards and unsustainable arsenic mitigation programs have aggravated the arsenic calamity in the GRB and put millions of lives in danger. This alarming situation resembles a ticking time bomb. We feel that after 29 years of arsenic research in the GRB, we have seen the tip of the iceberg with respect to the actual magnitude of the catastrophe; thus, a reduced arsenic standard for drinking water, testing all available drinking water sources, and sustainable and cost-effective arsenic mitigation programs that include the participation of the people are urgently needed. PMID:29360747

Degradation of Mcl-1 by granzyme B: implications for Bim-mediated mitochondrial apoptotic events.

PubMed

Han, Jie; Goldstein, Leslie A; Gastman, Brian R; Froelich, Christopher J; Yin, Xiao-Ming; Rabinowich, Hannah

2004-05-21

Recent studies have suggested that in the absence of Bid, granzyme B (GrB) can utilize an unknown alternative pathway to mediate mitochondrial apoptotic events. The current study has elucidated just such a pathway for GrB-mediated mitochondrial apoptotic alterations. Two Bcl-2 family members have been identified as interactive players in this newly discovered mitochondrial response to GrB: the pro-survival protein Mcl-1L and the pro-apoptotic protein, Bim. Expression of Mcl-1L, which localizes mainly to the outer mitochondrial membrane, decreases significantly in cells subjected to CTL-free cytotoxicity mediated by a combination of GrB and replication-deficient adenovirus. The data suggest that Mcl-1L is a substrate for GrB and for caspase-3, but the two enzymes appear to target different cleavage sites. The cleavage pattern of endogenous Mcl-1L resembles that of in vitro translated Mcl-1L subjected to similar proteolytic activity. Co-immunoprecipitation experiments performed with endogenous as well as with in vitro translated proteins suggest that Mcl-1L is a high affinity binding partner of the three isoforms of Bim (extra-long, long, and short). Bim, a BH3-only protein, is capable of mediating the release of mitochondrial cytochrome c, and this activity is inhibited by the presence of exogenous Mcl-1L. The findings presented herein imply that Mcl-1L degradation by either GrB or caspase-3 interferes with Bim sequestration by Mcl-1L.

Groundwater Arsenic Contamination in the Ganga River Basin: A Future Health Danger.

PubMed

Chakraborti, Dipankar; Singh, Sushant K; Rahman, Mohammad Mahmudur; Dutta, Rathindra Nath; Mukherjee, Subhas Chandra; Pati, Shyamapada; Kar, Probir Bijoy

2018-01-23

This study highlights the severity of arsenic contamination in the Ganga River basin (GRB), which encompasses significant geographic portions of India, Bangladesh, Nepal, and Tibet. The entire GRB experiences elevated levels of arsenic in the groundwater (up to 4730 µg/L), irrigation water (~1000 µg/L), and in food materials (up to 3947 µg/kg), all exceeding the World Health Organization's standards for drinking water, the United Nations Food and Agricultural Organization's standard for irrigation water (100 µg/L), and the Chinese Ministry of Health's standard for food in South Asia (0.15 mg/kg), respectively. Several individuals demonstrated dermal, neurological, reproductive, cognitive, and cancerous effects; many children have been diagnosed with a range of arsenicosis symptoms, and numerous arsenic-induced deaths of youthful victims are reported in the GRB. Victims of arsenic exposure face critical social challenges in the form of social isolation and hatred by their respective communities. Reluctance to establish arsenic standards and unsustainable arsenic mitigation programs have aggravated the arsenic calamity in the GRB and put millions of lives in danger. This alarming situation resembles a ticking time bomb. We feel that after 29 years of arsenic research in the GRB, we have seen the tip of the iceberg with respect to the actual magnitude of the catastrophe; thus, a reduced arsenic standard for drinking water, testing all available drinking water sources, and sustainable and cost-effective arsenic mitigation programs that include the participation of the people are urgently needed.

Testing local Lorentz invariance with short-range gravity

DOE PAGES

Kostelecký, V. Alan; Mewes, Matthew

2017-01-10

The Newton limit of gravity is studied in the presence of Lorentz-violating gravitational operators of arbitrary mass dimension. The linearized modified Einstein equations are obtained and the perturbative solutions are constructed and characterized. We develop a formalism for data analysis in laboratory experiments testing gravity at short range and demonstrate that these tests provide unique sensitivity to deviations from local Lorentz invariance.

Baryogenesis in Lorentz-violating gravity theories

NASA Astrophysics Data System (ADS)

Sakstein, Jeremy; Solomon, Adam R.

2017-10-01

Lorentz-violating theories of gravity typically contain constrained vector fields. We show that the lowest-order coupling of such vectors to U (1)-symmetric scalars can naturally give rise to baryogenesis in a manner akin to the Affleck-Dine mechanism. We calculate the cosmology of this new mechanism, demonstrating that a net B - L can be generated in the early Universe, and that the resulting baryon-to-photon ratio matches that which is presently observed. We discuss constraints on the model using solar system and astrophysical tests of Lorentz violation in the gravity sector. Generic Lorentz-violating theories can give rise to the observed matter-antimatter asymmetry without violating any current bounds.

Relativistic Anandan quantum phase and the Aharonov–Casher effect under Lorentz symmetry breaking effects in the cosmic string spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakke, K., E-mail: kbakke@fisica.ufpb.br; Furtado, C., E-mail: furtado@fisica.ufpb.br; Belich, H., E-mail: belichjr@gmail.com

2016-09-15

From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the violation of the Lorentz symmetry and write an effective metric for the cosmic string spacetime. Then, we investigate the arising of an analogue of the Anandan quantum phase for a relativistic Dirac neutral particle with a permanent magnetic dipole moment in the cosmic string spacetime under Lorentz symmetry breaking effects. Besides, we analyse the influence of the effects of the Lorentz symmetry violation and the topology of the defect on the Aharonov–Casher geometric quantum phase in the nonrelativistic limit.

Searching for photon-sector Lorentz violation using gravitational-wave detectors

NASA Astrophysics Data System (ADS)

Kostelecký, V. Alan; Melissinos, Adrian C.; Mewes, Matthew

2016-10-01

We study the prospects for using interferometers in gravitational-wave detectors as tools to search for photon-sector violations of Lorentz symmetry. Existing interferometers are shown to be exquisitely sensitive to tiny changes in the effective refractive index of light occurring at frequencies around and below the microhertz range, including at the harmonics of the frequencies of the Earth's sidereal rotation and annual revolution relevant for tests of Lorentz symmetry. We use preliminary data obtained by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 2006-2007 to place constraints on coefficients for Lorentz violation in the photon sector exceeding current limits by about four orders of magnitude.

Diffusion limit of Lévy-Lorentz gas is Brownian motion

NASA Astrophysics Data System (ADS)

Magdziarz, Marcin; Szczotka, Wladyslaw

2018-07-01

In this paper we analyze asymptotic behaviour of a stochastic process called Lévy-Lorentz gas. This process is aspecial kind of continuous-time random walk in which walker moves in the fixed environment composed of scattering points. Upon each collision the walker performs a flight to the nearest scattering point. This type of dynamics is observed in Lévy glasses or long quenched polymers. We show that the diffusion limit of Lévy-Lorentz gas with finite mean distance between scattering centers is the standard Brownian motion. Thus, for long times the behaviour of the Lévy-Lorentz gas is close to the diffusive regime.

Possible role of gamma ray bursts on life extinction in the universe.

PubMed

Piran, Tsvi; Jimenez, Raul

2014-12-05

As a copious source of gamma rays, a nearby galactic gamma ray burst (GRB) can be a threat to life. Using recent determinations of the rate of GRBs, their luminosity function, and properties of their host galaxies, we estimate the probability that a life-threatening (lethal) GRB would take place. Amongst the different kinds of GRBs, long ones are most dangerous. There is a very good chance (but no certainty) that at least one lethal GRB took place during the past 5 gigayears close enough to Earth as to significantly damage life. There is a 50% chance that such a lethal GRB took place during the last 500×10^{6}  years, causing one of the major mass extinction events. Assuming that a similar level of radiation would be lethal to life on other exoplanets hosting life, we explore the potential effects of GRBs to life elsewhere in the Galaxy and the Universe. We find that the probability of a lethal GRB is much larger in the inner Milky Way (95% within a radius of 4 kpc from the galactic center), making it inhospitable to life. Only at the outskirts of the Milky Way, at more than 10 kpc from the galactic center, does this probability drop below 50%. When considering the Universe as a whole, the safest environments for life (similar to the one on Earth) are the lowest density regions in the outskirts of large galaxies, and life can exist in only ≈10% of galaxies. Remarkably, a cosmological constant is essential for such systems to exist. Furthermore, because of both the higher GRB rate and galaxies being smaller, life as it exists on Earth could not take place at z>0.5. Early life forms must have been much more resilient to radiation.

Novel adapter proteins that link the human GM-CSF receptor to the phosphatidylino-sitol 3-kinase and Shc/Grb2/ras signaling pathways.

PubMed

Jücker, M; Feldman, R A

1996-01-01

We have used a human GM-CSF-dependent hematopoietic cell line that responds to physiological concentrations of hGM-CSF to analyze a set of signaling events that occur in normal myelopoiesis and whose deregulation may lead to leukemogenesis. Stimulation of these cells with hGM-CSF induced the assembly of multimeric complexes that contained known and novel phosphotyrosyl proteins. One of the new proteins was a major phosphotyrosyl substrate of 76-85 kDa (p80) that was directly associated with the p85 subunit of phosphatidylinositol (PI) 3-kinase through the SH2 domains of p85. p80 also associated with the beta subunit of the activated hGM-CSF receptor, and assembly of this complex correlated with activation of PI 3-kinase. A second phosphotyrosyl protein we identified, p140, associated with the Shc and Grb2 adapter proteins by direct binding to a novel phosphotyrosine-interacting domain located at the N-terminus of Shc. and to the SH3 domains of Grb2, respectively. The Shc/p140/Grb2 complex was found to be constitutively activated in acute myeloid leukemia cells, indicating that activation of this pathway may be a necessary step in the development of some leukemias. The p80/p85/PI 3-kinase and the Shc/Grb2/p140 complexes were tightly associated with Src family kinases, which were prime candidates for phosphorylation of Shc, p80, p140 and other phosphotyrosyl substrates present in these complexes. Our studies suggest that p80 and p140 may link the hGM-CSF receptor to the PI 3-kinase and Shc/Grb2/ras signaling pathways, respectively, and that abnormal activation of hGM-CSF-dependent targets may play a role in leukemogenesis.

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VIII. A Comparison to Cosmological Short-duration Gamma-Ray Bursts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fong, W.; Berger, E.; Blanchard, P. K.

Here, we present a comprehensive comparison of the properties of the radio through X-ray counterpart of GW170817 and the properties of short-duration gamma-ray bursts (GRBs). For this effort, we utilize a sample of 36 short GRBs spanning a redshift range ofmore » $$z \\approx 0.12-2.6$$ discovered over 2004-2017. We find that the counterpart to GW170817 has an isotropic-equivalent luminosity that is $$\\approx 3000$$ times less than the median value of on-axis short GRB X-ray afterglows, and $$\\gtrsim10^{4}$$ times less than that for detected short GRB radio afterglows. Moreover, the allowed jet energies and particle densities inferred from the radio and X-ray counterparts to GW170817 and on-axis short GRB afterglows are remarkably similar, suggesting that viewing angle effects are the dominant, and perhaps only, difference in their observed radio and X-ray behavior. From comparison to previous claimed kilonovae following short GRBs, we find that the optical and near-IR counterpart to GW170817 is comparatively under-luminous by a factor of $$\\approx 3-5$$, indicating a range of kilonova luminosities and timescales. A comparison of the optical limits following short GRBs on $$\\lesssim 1$$ day timescales also rules out a "blue" kilonova of comparable optical isotropic-equivalent luminosity in one previous short GRB. Finally, we investigate the host galaxy of GW170817, NGC4993, in the context of short GRB host galaxy stellar population properties. We find that NGC4993 is superlative in terms of its large luminosity, old stellar population age, and low star formation rate compared to previous short GRB hosts. Additional events within the Advanced LIGO/VIRGO volume will be crucial in delineating the properties of the host galaxies of NS-NS mergers, and connecting them to their cosmological counterparts.« less

iPTF17cw: An Engine-driven Supernova Candidate Discovered Independent of a Gamma-Ray Trigger

NASA Astrophysics Data System (ADS)

Corsi, A.; Cenko, S. B.; Kasliwal, M. M.; Quimby, R.; Kulkarni, S. R.; Frail, D. A.; Goldstein, A. M.; Blagorodnova, N.; Connaughton, V.; Perley, D. A.; Singer, L. P.; Copperwheat, C. M.; Fremling, C.; Kupfer, T.; Piascik, A. S.; Steele, I. A.; Taddia, F.; Vedantham, H.; Kutyrev, A.; Palliyaguru, N. T.; Roberts, O.; Sollerman, J.; Troja, E.; Veilleux, S.

2017-09-01

We present the discovery, classification, and radio-to-X-ray follow-up observations of iPTF17cw, a broad-lined (BL) type Ic supernova (SN) discovered by the intermediate Palomar Transient Factory (iPTF). Although it is unrelated to the gravitational wave trigger, this SN was discovered as a happy by-product of the extensive observational campaign dedicated to the follow-up of Advanced LIGO event GW 170104. The spectroscopic properties and inferred peak bolometric luminosity of iPTF17cw are most similar to the gamma-ray-burst (GRB)-associated SN, SN 1998bw, while the shape of the r-band light curve is most similar to that of the relativistic SN, SN 2009bb. Karl G. Jansky Very Large Array (VLA) observations of the iPTF17cw field reveal a radio counterpart ≈10 times less luminous than SN 1998bw, and with a peak radio luminosity comparable to that of SN 2006aj/GRB 060218 and SN 2010bh/GRB 100316D. Our radio observations of iPTF17cw imply a relativistically expanding outflow. However, further late-time observations with the VLA in its most extended configuration are needed to confirm fading of the iPTF17cw radio counterpart at all frequencies. X-ray observations carried out with Chandra reveal the presence of an X-ray counterpart with a luminosity similar to that of SN 2010bh/GRB 100316D. Searching the Fermi catalog for possible γ-rays reveals that GRB 161228B is spatially and temporally compatible with iPTF17cw. The similarity to SN 1998bw and SN 2009bb, the radio and X-ray detections, and the potential association with GRB 161228B all point to iPTF17cw being a new candidate member of the rare sample of optically discovered engine-driven BL-Ic SNe associated with relativistic ejecta.

iPTF17cw: An Engine-driven Supernova Candidate Discovered Independent of a Gamma-Ray Trigger

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corsi, A.; Palliyaguru, N. T.; Cenko, S. B.

We present the discovery, classification, and radio-to-X-ray follow-up observations of iPTF17cw, a broad-lined (BL) type Ic supernova (SN) discovered by the intermediate Palomar Transient Factory (iPTF). Although it is unrelated to the gravitational wave trigger, this SN was discovered as a happy by-product of the extensive observational campaign dedicated to the follow-up of Advanced LIGO event GW 170104. The spectroscopic properties and inferred peak bolometric luminosity of iPTF17cw are most similar to the gamma-ray-burst (GRB)-associated SN, SN 1998bw, while the shape of the r -band light curve is most similar to that of the relativistic SN, SN 2009bb. Karl G.more » Jansky Very Large Array (VLA) observations of the iPTF17cw field reveal a radio counterpart ≈10 times less luminous than SN 1998bw, and with a peak radio luminosity comparable to that of SN 2006aj/GRB 060218 and SN 2010bh/GRB 100316D. Our radio observations of iPTF17cw imply a relativistically expanding outflow. However, further late-time observations with the VLA in its most extended configuration are needed to confirm fading of the iPTF17cw radio counterpart at all frequencies. X-ray observations carried out with Chandra reveal the presence of an X-ray counterpart with a luminosity similar to that of SN 2010bh/GRB 100316D. Searching the Fermi catalog for possible γ -rays reveals that GRB 161228B is spatially and temporally compatible with iPTF17cw. The similarity to SN 1998bw and SN 2009bb, the radio and X-ray detections, and the potential association with GRB 161228B all point to iPTF17cw being a new candidate member of the rare sample of optically discovered engine-driven BL-Ic SNe associated with relativistic ejecta.« less

The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. VIII. A Comparison to Cosmological Short-duration Gamma-Ray Bursts

DOE PAGES

Fong, W.; Berger, E.; Blanchard, P. K.; ...

2017-10-16

Here, we present a comprehensive comparison of the properties of the radio through X-ray counterpart of GW170817 and the properties of short-duration gamma-ray bursts (GRBs). For this effort, we utilize a sample of 36 short GRBs spanning a redshift range ofmore » $$z \\approx 0.12-2.6$$ discovered over 2004-2017. We find that the counterpart to GW170817 has an isotropic-equivalent luminosity that is $$\\approx 3000$$ times less than the median value of on-axis short GRB X-ray afterglows, and $$\\gtrsim10^{4}$$ times less than that for detected short GRB radio afterglows. Moreover, the allowed jet energies and particle densities inferred from the radio and X-ray counterparts to GW170817 and on-axis short GRB afterglows are remarkably similar, suggesting that viewing angle effects are the dominant, and perhaps only, difference in their observed radio and X-ray behavior. From comparison to previous claimed kilonovae following short GRBs, we find that the optical and near-IR counterpart to GW170817 is comparatively under-luminous by a factor of $$\\approx 3-5$$, indicating a range of kilonova luminosities and timescales. A comparison of the optical limits following short GRBs on $$\\lesssim 1$$ day timescales also rules out a "blue" kilonova of comparable optical isotropic-equivalent luminosity in one previous short GRB. Finally, we investigate the host galaxy of GW170817, NGC4993, in the context of short GRB host galaxy stellar population properties. We find that NGC4993 is superlative in terms of its large luminosity, old stellar population age, and low star formation rate compared to previous short GRB hosts. Additional events within the Advanced LIGO/VIRGO volume will be crucial in delineating the properties of the host galaxies of NS-NS mergers, and connecting them to their cosmological counterparts.« less

Granzyme B mediated function of Parvovirus B19-specific CD4+ T cells

PubMed Central

Kumar, Arun; Perdomo, Maria F; Kantele, Anu; Hedman, Lea; Hedman, Klaus; Franssila, Rauli

2015-01-01

A novel conception of CD4+ T cells with cytolytic potential (CD4+ CTL) is emerging. These cells appear to have a part in controlling malignancies and chronic infections. Human parvovirus B19 can cause a persistent infection, yet no data exist on the presence of B19-specific CD4+ CTLs. Such cells could have a role in the pathogenesis of some autoimmune disorders reported to be associated with B19. We explored the cytolytic potential of human parvovirus B19-specific T cells by stimulating peripheral blood mononuclear cell (PBMC) with recombinant B19-VP2 virus-like particles. The cytolytic potential was determined by enzyme immunoassay-based quantitation of granzyme B (GrB) and perforin from the tissue culture supernatants, by intracellular cytokine staining (ICS) and by detecting direct cytotoxicity. GrB and perforin responses with the B19 antigen were readily detectable in B19-seropositive individuals. T-cell depletion, HLA blocking and ICS experiments showed GrB and perforin to be secreted by CD4+ T cells. CD4+ T cells with strong GrB responses were found to exhibit direct cytotoxicity. As anticipated, ICS of B19-specific CD4+ T cells showed expected co-expression of GrB, perforin and interferon gamma (IFN-γ). Unexpectedly, also a strong co-expression of GrB and interleukin 17 (IL-17) was detected. These cells expressed natural killer (NK) cell surface marker CD56, together with the CD4 surface marker. To our knowledge, this is the first report on virus-specific CD4+ CTLs co-expressing CD56 antigen. Our results suggest a role for CD4+ CTL in B19 immunity. Such cells could function within both immune regulation and triggering of autoimmune phenomena such as systemic lupus erythematosus (SLE) or rheumatoid arthritis. PMID:26246896

Deep Photometry of GRB 041006 Afterglow: Hypernova Bump at Redshift z = 0.716

NASA Astrophysics Data System (ADS)

Stanek, K. Z.; Garnavich, P. M.; Nutzman, P. A.; Hartman, J. D.; Garg, A.; Adelberger, K.; Berlind, P.; Bonanos, A. Z.; Calkins, M. L.; Challis, P.; Gaudi, B. S.; Holman, M. J.; Kirshner, R. P.; McLeod, B. A.; Osip, D.; Pimenova, T.; Reiprich, T. H.; Romanishin, W.; Spahr, T.; Tegler, S. C.; Zhao, X.

2005-06-01

We present deep optical photometry of the afterglow of gamma-ray burst (GRB) 041006 and its associated hypernova obtained over 65 days after detection (55 R-band epochs on 10 different nights). Our early data (t<4 days) joined with published GCN data indicate a steepening decay, approaching Fν~t-0.6 at early times (t<<1 day) and Fν~t-1.3 at late times. The break at tb=0.16+/-0.04 days is the earliest reported jet break among all GRB afterglows. During our first night, we obtained 39 exposures spanning 2.15 hr from 0.62 to 0.71 days after the burst that reveal a smooth afterglow, with an rms deviation of 0.024 mag from the local power-law fit, consistent with photometric errors. After t~4 days, the decay slows considerably, and the light curve remains approximately flat at R~24 mag for a month before decaying by another magnitude to reach R~25 mag 2 months after the burst. This ``bump'' is well fit by a k-corrected light curve of supernova SN 1998bw, but only if stretched by a factor of 1.38 in time. In comparison with the other GRB-related SN bumps, GRB 041006 stakes out new parameter space for GRBs/SNe, with a very bright and significantly stretched late-time SN light curve. Within a small sample of fairly well observed GRB/SN bumps, we see a hint of a possible correlation between their peak luminosity and their ``stretch factor,'' broadly similar to the well-studied Phillips relation for the Type Ia supernovae. Based on data from the MMT Observatory 6.5 m telescope, the 1.8 m Vatican Advanced Technology Telescope, the Magellan 6.5 m Baade and Clay telescopes, and the Keck II 10 m telescope.

SN 2013dx associated with GRB 130702A: a detailed photometric and spectroscopic monitoring and a study of the environment

NASA Astrophysics Data System (ADS)

D'Elia, Valerio

2015-08-01

Long duration gamma-ray bursts (GRBs) and broad-line, type Ic supernovae (SNe) are strongly connected. We aim at characterizing SN 2013dx, associated with GRB 130702A, through sensitive and extensive ground-based observational campaigns in the optical-IR band.We monitored the field of the Swift GRB 130702A (redshift z = 0.145) using the 8.2-m VLT, the 3.6-m TNG and the 0.6-m REM telescopes during the time interval between 4 and 40 days after the burst. Photometric and spectroscopic observations revealed the presence of the associated Type Ic SN 2013dx. Our multi-band photometry allowed the construction of a bolometric light curve.The bolometric light curve of SN 2013dx resembles that of 2003dh (associated with GRB 030329), but is ~ 10% faster and ~25% dimmer. From this we infer a synthesized 56Ni mass of ~0.3 solar masses. The multi-epoch optical spectroscopy shows that the SN 2013dx behavior is best matched by SN 1998bw, among the other well-known low-z SNe associated with GRBs and XRFs, and by SN 2010ah, an energetic Type Ic SN not associated with any GRB. The photospheric velocity of the ejected material declines from ~ 2.7 X10^4 km/s at 8 rest frame days from the explosion, to ~3.5X103 km/s at 40 days. These values are extremely close to those of SN1998bw and 2010ah. We deduce for SN 2013dx a kinetic energy of (32 +/- 9)X10^51 erg, and an ejected mass of 7 +/- 1 solar masses. This suggests that the progenitor of SN2013dx had a mass of ~25 solar masses, i.e., 15-20% less massive than that of SN 1998bw.Finally, we perfom a study of the SN 2013dx environment, through spectroscopy of the closeby galaxies. 9 out of the 14 inspected galaxies lie within 0.03 in redshift from z=0.145, indicating that the host of GRB 130702A/SN 2013dx belongs to a group of galaxies, an unprecedented finding for a GRB-associated SN and, to our knowledge, for long GRBs in general.

Near-infrared instrumentation for rapid-response astronomy

NASA Astrophysics Data System (ADS)

Capone, John Isaac

gamma-ray bursts (GRBs) are the Universe's most luminous transient events. Since the discovery of GRBs was announced in 1973, efforts have been ongoing to obtain data over a broader range of the electromagnetic spectrum at the earliest possible times following the initial detection. The discovery of the theorized "afterglow'' emission in radio through X-ray bands in the late 1990s confirmed the cosmological nature of these events. At present, GRB afterglows are among the best probes of the early Universe (z ≥ 9). In addition to informing theories about GRBs themselves, observations of afterglows probe the circum-burst medium (CBM), properties of the host galaxies and the progress of cosmic reionization. To explore the early-time variability of afterglows, I have developed a generalized analysis framework which models near-infrared (NIR), optical, ultra-violet (UV) and X-ray light curves without assuming an underlying model. These fits are then used to construct the spectral energy distribution (SED) of afterglows at arbitrary times within the observed window. Physical models are then used to explore the evolution of the SED parameter space with time. I demonstrate that this framework produces evidence of the photodestruction of dust in the CBM of GRB 120119A, similar to the findings from a previous study of this afterglow. The framework is additionally applied to the afterglows of GRB 140419A and GRB 080607. In these cases the evolution of the SEDs appears consistent with the standard fireball model. Having introduced the scientific motivations for early-time observations, I introduce the Rapid Infrared Imager-Spectrometer (RIMAS). Once commissioned on the 4.3 meter Discovery Channel Telescope (DCT), RIMAS will be used to study the afterglows of GRBs through photometric and spectroscopic observations beginning within minutes of the initial burst. The instrument will operate in the NIR, from 0.97 microm to 2.37 microm, permitting the detection of very high redshift (z ≥ 7) afterglows which are attenuated at shorter wavelengths by Lyman-alpha absorption in the intergalactic medium (IGM). A majority of my graduate work has been spent designing and aligning RIMAS's cryogenic ( 80 K) optical systems. Design efforts have included an original camera used to image the field surrounding spectroscopic slits, tolerancing and optimizing all of the instrument's optics, thermal modeling of optomechanical systems, and modeling the diffraction efficiencies for some of the dispersive elements. To align the cryogenic optics, I developed a procedure that was successfully used for a majority of the instrument's sub-assemblies. My work on this cryogenic instrument has necessitated experimental and computational projects to design and validate designs of several subsystems. Two of these projects describe simple and effective measurements of optomechanical components in vacuum and at cryogenic temperatures using an 8-bit CCD camera. Models of heat transfer via electrical harnesses used to provide current to motors located within the cryostat are also presented.

Testing Lorentz invariance violations in the tritium beta-decay anomaly

NASA Astrophysics Data System (ADS)

Carmona, J. M.; Cortés, J. L.

2000-11-01

We consider a Lorentz non-invariant dispersion relation for the neutrino, which would produce unexpected effects with neutrinos of few eV, exactly where the tritium beta-decay anomaly is found. We use this anomaly to put bounds on the violation of Lorentz invariance. We discuss other consequences of this non-invariant dispersion relation in neutrino experiments and high-energy cosmic-ray physics.

Measurement of the Lorentz-FitzGerald body contraction

NASA Astrophysics Data System (ADS)

Rafelski, Johann

2018-02-01

A complete foundational discussion of acceleration in the context of Special Relativity (SR) is presented. Acceleration allows the measurement of a Lorentz-FitzGerald body contraction created. It is argued that in the back scattering of a probing laser beam from a relativistic flying electron cloud mirror generated by an ultra-intense laser pulse, a first measurement of a Lorentz-FitzGerald body contraction is feasible.

Concluding Remarks: The Current Status and Future Prospects for GRB Astronomy

NASA Technical Reports Server (NTRS)

Gehrels, Neil

2009-01-01

We are in a remarkable period of discovery in GRB astronomy. The current satellites including Swift, Fermi. AGILE and INTEGRAL are detecting and observing bursts of all varieties. Increasing capabilities for follow-up observations on the ground and in space are leading to rapid and deep coverage across the electromagnetic spectrum, The future will see continued operation of the current experiments and with future missions like SVOM plus possible rni_Ssions like JANUS and EXIST. An exciting expansion of capabilities is occurring in areas of gravitational waves and neutrinos that could open new windows on the GRB phenomenon. Increased IR capabilities on the ground and with missions like JWST will enable further exploration of high redshift bursts. The future is bright.

Gamma-ray bursts at high and very high energies

NASA Astrophysics Data System (ADS)

Piron, Frédéric

2016-06-01

Gamma-Ray Bursts (GRBs) are extra-galactic and extremely energetic transient emissions of gamma rays, which are thought to be associated with the death of massive stars or the merger of compact objects in binary systems. Their huge luminosities involve the presence of a newborn stellar-mass black hole emitting a relativistic collimated outflow, which accelerates particles and produces non-thermal emissions from the radio domain to the highest energies. In this article, I review recent progresses in the understanding of GRB jet physics above 100 MeV, based on Fermi observations of bright GRBs. I discuss the physical implications of these observations and their impact on GRB modeling, and I present some prospects for GRB observation at very high energies in the near future.

Relativistic Hydrodynamics and Spectral Evolution of GRB Jets

NASA Astrophysics Data System (ADS)

Cuesta-Martínez, C.

2017-09-01

In this thesis we study the progenitor systems of long gamma-ray bursts (GRBs) using numerical models of their dynamics and the electromagnetic emission. Of all the possible classes of events, we focus on those showing a prominent component of thermal emission, which might be generated due to the interaction of a relativistic jet with the medium into which it is propagating. The main part of the thesis is devoted to modelling GRBs from two different clases of progenitors: ultra-long GRBs dominated by blackbody emission and GRBs associated with core-collapse supernovae (SNe). The study of GRB jets and their radiative emission has been basically divided into two steps. First, the dynamical evolution of relativistic jets can be simulated by means of multidimensional special relativistic hydrodynamic simulations which have been performed with the MRGENESIS code. Second, the synthetic emission from such jets is computed with the relativistic radiative transfer code SPEV in a post-processing stage assuming different radiative processes in which we follow the temporal and spectral evolution of the emitted radiation. An instrumental part of this project consisted in extending SPEV to include thermal processes, such as thermal bremsstrahlung, in order to account for the thermal signal that may arise in some GRBs. In the first part of this thesis, we extend an existing theoretical model to explain the class of blackbody-dominated GRBs (BBD-GRBs), i.e., long lasting events characterized by the presence of a notable thermal component trailing the GRB prompt emission, and a rather weak traditional afterglow. GRB 101225A, the "Christmas burst", is the most prominent member of this class. It has been suggested that BBD-GRBs could result from the merger of a binary system formed by a neutron star and the Helium core of an evolved, massive star. We model in 2D the propagation of ultrarelativistic jets through the environments created by such mergers. We outline the most relevant dynamical details of the jet propagation and connect them to the generation of thermal radiation in GRB events akin to that of the Christmas burst. A comprehensive parameter study of the jet/environment interaction has been performed and synthetic light curves are confronted with the observational data. The thermal emission in our models originates from the interaction between the jet and the hydrogen envelope ejected during the neutron star/He core merger. We find that the lack of a classical afterglow and the accompanying thermal emission in BBD-GRBs can be explained by the interaction of an ultrarelativistic jet with a toroidally shaped ejecta whose axis coincides with the binary rotation axis. We also find that the synchrotron emission of the forward shock of the jet is dominant during the early phases of the evolution, along which that shock is still moderately relativistic. The contribution of the reverse shock is of the same magnitude as that of the forward shock during the first 80 min after the GRB. Later, it quickly fades because the jet/environment interaction chokes the ultrarelativistic jet beam and effectively dumps the reverse shock. We highlight that, in agreement with observations, we obtain rather flat light curves during the first 2 days after the GRB, and a spectral evolution consistent with the observed reddening of the system. Besides, we obtain that this spectral inversion and reddening happening at about 2 days in the Christmas burst can be related to the time at which the massive shell, ejected in an early phase of the common-envelope evolution of the progenitor system, is completely ablated by the ultrarelativistic jet. In the second part of this thesis, we study more canonical progenitor systems of GRBs, namely single massive stars on the brink of collapse. Motivated by the many associations of GRBs with energetic SN explosions, we study the propagation of relativistic jets within the progenitor star and the circumstellar medium. Particular attention is paid to the interaction between the jets and a SN shock wave launched briefly before the jets start to propagate. We have followed the dynamical evolution in one spatial dimension (1D) of the SN ejecta alone. Employing 2D axisymmetric relativistic hydrodynamic simulations we have explored the dynamical evolution of jets running into the medium left behind by the SN shock. For completeness, we have studied also the case in which no SN has formed. Based on analytic considerations and verified with an extensive set of simulations, we have estimated a threshold intrinsic jet luminosity, L_j^{thr}. For the stellar model under consideration here it is L_j^{thr} ≳ 1E49 erg s^{-1}. The observed equivalent isotropic γ-ray luminosity, L_{iso,γ} - 4 ɛ_γ L_j / θ_{BO}^2, crucially depends on the jet opening angle after breakout, θ_{BO}, and on the efficiency in converting the intrinsic jet luminosity into γ-radiation, ɛ_γ. Highly energetic jets can produce low-luminosity events if either their opening angle after the breakout is large, which is found in our models, or if the conversion efficiency of kinetic and internal energy into radiation is low enough. Beyond these theoretical analysis, we show how the presence of a SN shock wave modifies the jet propagation. One of the main goals of this chapter was studying the emission with SPEV at the breakout of the jet or the SN ejecta. However this part suffered from technical problems, in particular excessive numerical diffusion caused by a lack of numerical resolution. Due to computing time restrictions, we could not properly obtain long-time light curves and spectra and could only compute the thermal emission. Therefore, our conclusions have to be considered preliminary. We have obtained rather low luminosities inconsistent with previous calculations in the literature. We find that the SN flash of our models is ≳ 1000 times dimmer than that of one of the prototype examples of GRB/SNe (GRB 060218/SN 2006aj) or X-ray flashes (XRF) associated to SNe (XRF 080109/SN 2008D). However, observations of GRB/SNe show heterogeneous properties, with cases in which the bolometric luminosity is orders of magnitude smaller than in the previous examples. Besides, X-ray peak times of 10 s are theoretically expected for compact WR progenitors. Both facts, make our models partly consistent with the existing phenomenology. From the analysis of the asymptotic Lorentz factor in the whole cavity blown by the different jets, we foresee that the high-energy transients we may produce will be more similar to XRF than to GRBs. Indeed, our jet events display their peak specific luminosity in the extreme UV band, rather than in the X-ray band, and clearly a fainter γ-ray luminosity ( 2-4 orders of magnitude smaller than in the X-ray band). Finally, we find that the very early observational signature of our different jet models (prior to the luminosity peak) below the γ-ray band is very similar comparing jets with the same intrinsic luminosity. This happens in spite of the substantially different hydrodynamic evolution of models which either interact with a pre-existing SN ejecta or propagate through the unmodified stellar progenitor. We expect this similarity lasting for time scales of the order of the light-crossing time of the transversal size of the emitting region ( 1-2 s). Thus, we shall continue our models for even longer evolutionary times and, as argued above, employing a finer grid resolution.

Initial conditions for dark soliton generation in normal-dispersion fiber lasers.

PubMed

Ge, Y Q; Luo, J L; Li, L; Jin, X X; Tang, D Y; Shen, D Y; Zhang, S M; Zhao, L M

2015-01-01

We report results of numerical simulations on the various initial conditions for dark soliton generation in an all-normal-dispersion fiber laser. All the dark solitons generated are odd dark solitons. Differently from the dark soliton generation in fibers, where an arbitrary dip could evolve into a dark soliton, it is found that the dark soliton can originate only from an initial dip with a certain parameter requirement. A bright pulse with either a hyperbolic secant square, Gaussian, or Lorentz profile can be developed into a dark soliton, provided that the parameters of the initial bright pulse are selected. Dark solitons can be generated in fiber lasers only if there is a phase jump, and this phase jump can be maintained and evolve to π during the pulse evolution.

Improved test of Lorentz invariance in electrodynamics

NASA Astrophysics Data System (ADS)

Wolf, Peter; Bize, Sébastien; Clairon, André; Santarelli, Giorgio; Tobar, Michael E.; Luiten, André N.

2004-09-01

We report new results of a test of Lorentz invariance based on the comparison of a cryogenic sapphire microwave resonator and a hydrogen-maser. The experimental results are shown together with an extensive analysis of systematic effects. Previously, this experiment has set the most stringent constraint on Kennedy-Thorndike type violations of Lorentz invariance. In this work we present new data and interpret our results in the general Lorentz violating extension of the standard model of particle physics (SME). Within the photon sector of the SME, our experiment is sensitive to seven SME parameters. We marginally improve present limits on four of these, and by a factor seven to ten on the other three.

Strong binary pulsar constraints on Lorentz violation in gravity.

PubMed

Yagi, Kent; Blas, Diego; Yunes, Nicolás; Barausse, Enrico

2014-04-25

Binary pulsars are excellent laboratories to test the building blocks of Einstein's theory of general relativity. One of these is Lorentz symmetry, which states that physical phenomena appear the same for all inertially moving observers. We study the effect of violations of Lorentz symmetry in the orbital evolution of binary pulsars and find that it induces a much more rapid decay of the binary's orbital period due to the emission of dipolar radiation. The absence of such behavior in recent observations allows us to place the most stringent constraints on Lorentz violation in gravity, thus verifying one of the cornerstones of Einstein's theory much more accurately than any previous gravitational observation.

Convexity and concavity constants in Lorentz and Marcinkiewicz spaces

NASA Astrophysics Data System (ADS)

Kaminska, Anna; Parrish, Anca M.

2008-07-01

We provide here the formulas for the q-convexity and q-concavity constants for function and sequence Lorentz spaces associated to either decreasing or increasing weights. It yields also the formula for the q-convexity constants in function and sequence Marcinkiewicz spaces. In this paper we extent and enhance the results from [G.J.O. Jameson, The q-concavity constants of Lorentz sequence spaces and related inequalities, Math. Z. 227 (1998) 129-142] and [A. Kaminska, A.M. Parrish, The q-concavity and q-convexity constants in Lorentz spaces, in: Banach Spaces and Their Applications in Analysis, Conference in Honor of Nigel Kalton, May 2006, Walter de Gruyter, Berlin, 2007, pp. 357-373].

Search for a Lorentz-violating sidereal signal with atmospheric neutrinos in IceCube

NASA Astrophysics Data System (ADS)

Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Davis, J. C.; de Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lehmann, R.; Lünemann, J.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Matusik, M.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schlenstedt, S.; Schmidt, T.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Singh, K.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Voge, M.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.

2010-12-01

A search for sidereal modulation in the flux of atmospheric muon neutrinos in IceCube was performed. Such a signal could be an indication of Lorentz-violating physics. Neutrino oscillation models, derivable from extensions to the standard model, allow for neutrino oscillations that depend on the neutrino’s direction of propagation. No such direction-dependent variation was found. A discrete Fourier transform method was used to constrain the Lorentz and CPT-violating coefficients in one of these models. Because of the unique high energy reach of IceCube, it was possible to improve constraints on certain Lorentz-violating oscillations by 3 orders of magnitude with respect to limits set by other experiments.

The cosmic microwave background and pseudo-Nambu-Goldstone bosons: Searching for Lorentz violations in the cosmos

NASA Astrophysics Data System (ADS)

Leon, David; Kaufman, Jonathan; Keating, Brian; Mewes, Matthew

2017-01-01

One of the most powerful probes of new physics is the polarized cosmic microwave background (CMB). The detection of a nonzero polarization angle rotation between the CMB surface of last scattering and today could provide evidence of Lorentz-violating physics. The purpose of this paper is two-fold. First, we review one popular mechanism for polarization rotation of CMB photons: the pseudo-Nambu-Goldstone boson (PNGB). Second, we propose a method to use the POLARBEAR experiment to constrain Lorentz-violating physics in the context of the Standard Model Extension (SME), a framework to standardize a large class of potential Lorentz-violating terms in particle physics.