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Sample records for grb afterglow emission

  1. Early emission of rising optical afterglows: the case of GRB 060904B and GRB 070420

    NASA Astrophysics Data System (ADS)

    Klotz, A.; Gendre, B.; Stratta, G.; Galli, A.; Corsi, A.; Preger, B.; Cutini, S.; Pélangeon, A.; Atteia, J. L.; Boër, M.; Piro, L.

    2008-06-01

    Aims: We present the time-resolved optical emission of gamma-ray bursts GRB 060904B and GRB 070420 during their prompt and early afterglow phases. Methods: We used time resolved photometry from optical data taken by the TAROT telescope and time resolved spectroscopy at high energies from the Swift spacecraft instrument. Results: The optical emissions of both GRBs are found to increase from the end of the prompt phase, passing to a maximum of brightness at t_peak=9.2 min and 3.3 min for GRB 060904B and GRB 070420 respectively and then decrease. GRB 060904B presents a large optical plateau and a very large X-ray flare. We argue that the very large X-flare occurring near t_peak is produced by an extended internal engine activity and is only a coincidence with the optical emission. GRB 070420 observations would support this idea because there was no X-flare during the optical peak. The nature of the optical plateau of GRB 060904B is less clear and might be related to the late energy injection. Based on observations performed with TAROT at the Calern/OCA and La Silla/ESO observatories, GCN data archive and Swift public data archive.

  2. GRB off-axis afterglows and the emission from the accompanying supernovae

    NASA Astrophysics Data System (ADS)

    Kathirgamaraju, Adithan; Barniol Duran, Rodolfo; Giannios, Dimitrios

    2016-09-01

    Gamma-ray burst (GRB) afterglows are likely produced in the shock that is driven as the GRB jet interacts with the external medium. Long-duration GRBs are also associated with powerful supernovae (SNe). We consider the optical and radio afterglows of long GRBs for both blasts viewed along the jet axis (`on-axis' afterglows) and misaligned observes (`off-axis' afterglows). Comparing the optical emission from the afterglow with that of the accompanying SN, using SN 1998bw as an archetype, we find that only a few per cent of afterglows viewed off-axis are brighter than the SN. For observable optical off-axis afterglows, the viewing angle is at most twice the half-opening angle of the GRB jet. Radio off-axis afterglows should be detected with upcoming radio surveys within a few hundred Mpc. We propose that these surveys will act as `radio triggers', and that dedicated radio facilities should follow-up these sources. Follow-ups can unveil the presence of the radio SN remnant, if present. In addition, they can probe the presence of a mildly relativistic component, either associated with the GRB jet or the SN ejecta, expected in these sources.

  3. 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.

  4. MULTIWAVELENGTH OBSERVATIONS OF GRB 110731A: GeV EMISSION FROM ONSET TO AFTERGLOW

    SciTech Connect

    Ackermann, M.; Ajello, M.; Blandford, R. D.; Borgland, A. W.; Bottacini, E.; Buehler, R.; Cameron, R. A.; Asano, K.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Buson, S.; Bonamente, E.; Brigida, M.; Bruel, P.; Caraveo, P. A. E-mail: giacomov@slac.stanford.edu E-mail: srazzaque@ssd5.nrl.navy.mil E-mail: dgruber@mpe.mpg.de; and others

    2013-02-15

    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 {Gamma} {approx} 500-550.

  5. Synchrotron and inverse-Compton emissions from pairs formed in GRB afterglows (analytical treatment)

    SciTech Connect

    Panaitescu, A.; Vestrand, W. T.

    2014-10-01

    We calculate the synchrotron and inverse-Compton emissions from pairs formed in gamma-ray burst (GRB) afterglows from high-energy photons (above 100 MeV), assuming a power-law photon spectrum C {sub ν}∝ν{sup –2} and considering only the pairs generated from primary high-energy photons. The essential properties of these pairs (number, minimal energy, cooling energy, distribution with energy) and of their emission (peak flux, spectral breaks, spectral slope) are set by the observables GeV fluence Φ(t) = Ft and spectrum, and by the Lorentz factor, Γ, and magnetic field, B, of the source of high-energy photons, at observer time, t. Optical and X-ray pseudo light curves, F {sub ν}(Γ), are calculated for the given B; proper synchrotron self-Compton light curves are calculated by setting the dynamics Γ(t) of the high-energy photon source to be that of a decelerating, relativistic shock. It is found that the emission from pairs can accommodate the flux and decays of the optical flashes measured during the prompt (GRB) phase, but it decays faster than the X-ray plateaus observed during the delayed (afterglow) phase. The brightest pair optical emission is obtained for 100 < Γ < 500, and depends mostly on the GeV fluence, being independent of the source redshift. Emission from pairs formed during the GRB phase offers an alternate explanation to reverse-shock optical flashes. These two models may be distinguished based on their corresponding flux decay index-spectral slope relations, different correlations with the Large Area Telescope fluence, or through modeling of the afterglow multiwavelength data.

  6. PANCHROMATIC OBSERVATIONS OF THE TEXTBOOK GRB 110205A: CONSTRAINING PHYSICAL MECHANISMS OF PROMPT EMISSION AND AFTERGLOW

    SciTech Connect

    Zheng, W.; Shen, R. F.; Sakamoto, T.; Beardmore, A. P.; De Pasquale, M.; Wu, X. F.; Zhang, B.; Gorosabel, J.; Urata, Y.; Sugita, S.; Pozanenko, A.; Sahu, D. K.; Im, M.; Ukwatta, T. N.; Andreev, M.; Klunko, E. E-mail: rfshen@astro.utoronto.ca; and others

    2012-06-01

    We present a comprehensive analysis of a bright, long-duration (T{sub 90} {approx} 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb, and BOOTES telescopes when the gamma-ray burst (GRB) was still radiating in the {gamma}-ray band, with optical light curve showing correlation with {gamma}-ray data. Nearly 200 s of observations were obtained simultaneously from optical, X-ray, to {gamma}-ray (1 eV to 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution during the prompt emission phase. In particular, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard synchrotron emission model in the fast cooling regime. Shortly after prompt emission ({approx}1100 s), a bright (R = 14.0) optical emission hump with very steep rise ({alpha} {approx} 5.5) was observed, which we interpret as the reverse shock (RS) emission. It is the first time that the rising phase of an RS component has been closely observed. The full optical and X-ray afterglow light curves can be interpreted within the standard reverse shock (RS) + forward shock (FS) model. In general, the high-quality prompt and afterglow data allow us to apply the standard fireball model to extract valuable information, including the radiation mechanism (synchrotron), radius of prompt emission (R{sub GRB} {approx} 3 Multiplication-Sign 10{sup 13} cm), initial Lorentz factor of the outflow ({Gamma}{sub 0} {approx} 250), the composition of the ejecta (mildly magnetized), the collimation angle, and the total energy budget.

  7. Radio rebrightening of the GRB afterglow by the accompanying supernova

    NASA Astrophysics Data System (ADS)

    Barniol Duran, R.; Giannios, D.

    2015-12-01

    The gamma-ray burst (GRB) jet powers the afterglow emission by shocking the surrounding medium, and radio afterglow can now be routinely observed to almost a year after the explosion. Long-duration GRBs are accompanied by supernovae (SNe) that typically contain much more energy than the GRB jet. Here we consider the fact that the SN blast wave will also produce its own afterglow (supernova remnant emission), which will peak at much later time (since it is non-relativistic), when the SN blast wave transitions from a coasting phase to a decelerating Sedov-Taylor phase. We predict that this component will peak generally a few tens of years after the explosion and it will outshine the GRB powered afterglow well-before its peak emission. In the case of GRB 030329, where the external density is constrained by the ˜10-year coverage of the radio GRB afterglow, the radio emission is predicted to start rising over the next decade and to continue to increase for the following decades up to a level of ˜ mJy. Detection of the SN-powered radio emission will greatly advance our knowledge of particle acceleration in ˜0.1c shocks.

  8. SYNCHROTRON SELF-COMPTON EMISSION AS THE ORIGIN OF THE GAMMA-RAY AFTERGLOW OBSERVED IN GRB 980923

    SciTech Connect

    Fraija, N.; Gonzalez, M. M.; Lee, W. H. E-mail: magda@astro.unam.mx

    2012-05-20

    GRB 980923 was one of the brightest bursts observed by the Burst and Transient Source Experiment. Previous studies have detected two distinct components in addition to the main prompt episode, which is well described by a Band function. The first of these is a tail with a duration of {approx_equal} 400 s, while the second is a high-energy component lasting {approx_equal} 2 s. We summarize the observations and argue for a unified model in which the tail can be understood as the early {gamma}-ray afterglow from forward shock synchrotron emission, while the high-energy component arises from synchrotron self-Compton from the reverse shock. Consistency between the main assumption of thick shell emission and agreement between the observed and computed values for fluxes, break energies, starting times, and spectral indices leads to a requirement that the ejecta must be highly magnetized.

  9. GRB050525A : Multiband modelling of the afterglow

    NASA Astrophysics Data System (ADS)

    Resmi, Lekshmi; Misra, Kuntal; Castro-Tirado, Alberto

    2011-08-01

    The Swift era has posed a challenge to the standard blast-wave model of Gamma Ray Burst afterglows. The achromatic steepening of the afterglow lightcurves (`jet break') considered in the model as the signature of outflow collimation, has become almost rare. Several afterglows exhibited complex lightcurves that did not confirm by the predicted spectral--temporal `closure relations' of the blastwave model. Here we present optical observations and broadband modelling of the afterglow of GRB0505025A, a bright burst detected and followed up by Swift. We find that the overall evolution of the afterglow can not be explained by a single forward shock emission, though the late time evolution is compatible with the predictions of the standard afterglow model, including a jet break. We explain the afterglow evolution based on a two-component jet model and estimate the physical parameters.

  10. Panchromatic Observations of the Textbook GRB 110205A: Constraining Physical Mechanisms of Prompt Emission and Afterglow

    NASA Technical Reports Server (NTRS)

    Zheng, W.; Shen, R. F.; Sakamoto, T.; Beardmore, A. P.; De Pasquale, M.; Wu, X. F.; Gorosabel, J.; Urata, Y.; Sugita, S.; Zhang, B.; Pozanenko, A.; Nissinen, M.; Sahu, D. K.; Im, M.; Ukwatta, T. N.; Andreev, M.; Klunko, E.; Volnova, A.; Akerlof, C. W.; Anto, P.; Barthelmy, S. D.; Breeveld, A.; Carsenty, U.; Gehrels, N.; Sonbas, E.

    2011-01-01

    We present a comprehensive analysis of a bright, long duration (T(sub 90) approx. 257 s) GRB 110205A at redshift z = 2.22. The optical prompt emission was detected by Swift/UVOT, ROTSE-IIIb and BOOTES telescopes when the GRB was still radiating in the gamma-ray band. Thanks to its long duration, nearly 200 s of observations were obtained simultaneously from optical, X-ray to gamma-ray (1 eV - 5 MeV), which makes it one of the exceptional cases to study the broadband spectral energy distribution across 6 orders of magnitude in energy during the prompt emission phase. In particular, by fitting the time resolved prompt spectra, we clearly identify, for the first time, an interesting two-break energy spectrum, roughly consistent with the standard GRB synchrotron emission model in the fast cooling regime. Although the prompt optical emission is brighter than the extrapolation of the best fit X/ -ray spectra, it traces the -ray light curve shape, suggesting a relation to the prompt high energy emission. The synchrotron + synchrotron self-Compton (SSC) scenario is disfavored by the data, but the models invoking a pair of internal shocks or having two emission regions can interpret the data well. Shortly after prompt emission (approx. 1100 s), a bright (R = 14.0) optical emission hump with very steep rise ( alpha approx. 5.5) was observed which we interpret as the emission from the reverse shock. It is the first time that the rising phase of a reverse shock component has been closely observed.

  11. Polarization Evolution of the Afterglow of GRB 030329

    NASA Technical Reports Server (NTRS)

    Greiner, Jochen; Klose, Sylvio; Reinsch, Klaus; Schmid, Hans Martin; Sari, Re'em; Hartmann, Dieter H.; Kouveliotou, Chryssa; Rau, Arne; Palazzi, Eliana; Straubmeier, Christian

    2003-01-01

    The association of a supernova with GRB 030329l strongly supports the collapsar model of gamma-ray bursts (GRBs), where a relativistic jet forms after the progenitor star collapses. Such jets cannot be spatially resolved because of their cosmological distances. Their existence is conjectured based on breaks in GRB afterglow light curves and the theoretical desire to reduce the GRB energy requirements. Temporal evolution of polarization may provide independent evidence for the jet structure of the relativistic outflow. Small-level polarization (approx. 1-3%) has been reported for a few bursts, but the temporal evolution of polarization properties could not be established. Here, we report polarimetric observations of the afterglow of GRB 030329 with high signal-to-noise and high sampling frequency. We establish the polarization light curve, detect sustained polarization at the percent level, and find significant variability. The data imply that the afterglow magnetic field has small coherence length and is mostly random, probably generated by turbulence, in contrast with the high polarization detected in the prompt gamma-rays from GRB 02120618. Our results suggest a different structure and origin of the magnetic field in the prompt vs. afterglow emission regions.

  12. Simulation of Relativistic Shocks and Associated Self-Consistent Radiation for GRB Prompt Emission and Afterglows

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Mizuno, Y.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Guiriec, S.; Fishman, G. J.

    2010-01-01

    Plasma instabilities excited in collisionless shocks are responsible for particle acceleration. We have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. In the leading shock, electron density increases by a factor of about 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. This simulation corresponds to a case for gamma-ray burst afterglows. We will simulate colliding shells as an internal shock model for prompt emission. Turbulent magnetic fields generated by a slower shell will be collided by a faster shell. These magnetic fields contribute to the electron s transverse deflection behind the shock. We calculate the radiation from deflected electrons in the turbulent magnetic fields. The properties of this radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts

  13. X-ray flares in early GRB afterglows.

    PubMed

    Burrows, D N; Falcone, A; Chincarini, G; Morris, D; Romano, P; Hill, J E; Godet, O; Moretti, A; Krimm, H; Osborne, J P; Racusin, J; Mangano, V; Page, K; Perri, M; Stroh, M

    2007-05-15

    The Swift X-ray Telescope (XRT) has discovered that flares are quite common in early X-ray afterglows of gamma-ray bursts (GRBs), being observed in roughly 50% of afterglows with prompt follow-up observations. The flares range in fluence from a few per cent to approximately 100% of the fluence of the prompt emission (the GRB). Repetitive flares are seen, with more than four successive flares detected by the XRT in some afterglows. The rise and fall times of the flares are typically considerably smaller than the time since the burst. These characteristics suggest that the flares are related to the prompt emission mechanism, but at lower photon energies. We conclude that the most likely cause of these flares is late-time activity of the GRB central engine. PMID:17293338

  14. The Afterglows of Swift-era Gamma-Ray Bursts. II. Type I GRB versus Type II GRB Optical Afterglows

    NASA Astrophysics Data System (ADS)

    Kann, D. A.; Klose, S.; Zhang, B.; Covino, S.; Butler, N. R.; Malesani, D.; Nakar, E.; Wilson, A. C.; Antonelli, L. A.; Chincarini, G.; Cobb, B. E.; D'Avanzo, P.; D'Elia, V.; Della Valle, M.; Ferrero, P.; Fugazza, D.; Gorosabel, J.; Israel, G. L.; Mannucci, F.; Piranomonte, S.; Schulze, S.; Stella, L.; Tagliaferri, G.; Wiersema, K.

    2011-06-01

    Gamma-ray bursts (GRBs) have been separated into two classes, originally along the lines of duration and spectral properties, called "short/hard" and "long/soft." The latter have been conclusively linked to the explosive deaths of massive stars, while the former are thought to result from the merger or collapse of compact objects. In recent years, indications have been accumulating that the short/hard versus long/soft division does not map directly onto what would be expected from the two classes of progenitors, leading to a new classification scheme called Type I and Type II which is based on multiple observational criteria. We use a large sample of GRB afterglow and prompt-emission data (adding further GRB afterglow observations in this work) to compare the optical afterglows (or the lack thereof) of Type I GRBs with those of Type II GRBs. In comparison to the afterglows of Type II GRBs, we find that those of Type I GRBs have a lower average luminosity and show an intrinsic spread of luminosities at least as wide. From late and deep upper limits on the optical transients, we establish limits on the maximum optical luminosity of any associated supernova (SN), confirming older works and adding new results. We use deep upper limits on Type I GRB optical afterglows to constrain the parameter space of possible mini-SN emission associated with a compact-object merger. Using the prompt-emission data, we search for correlations between the parameters of the prompt emission and the late optical afterglow luminosities. We find tentative correlations between the bolometric isotropic energy release and the optical afterglow luminosity at a fixed time after the trigger (positive), and between the host offset and the luminosity (negative), but no significant correlation between the isotropic energy release and the duration of the GRBs. We also discuss three anomalous GRBs, GRB 060505, GRB 060614, and GRB 060121, in light of their optical afterglow luminosities. Based in part

  15. Prompt, early and afterglow optical observations of five γ-ray bursts: GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A

    NASA Astrophysics Data System (ADS)

    Gorbovskoy, E. S.; Lipunova, G. V.; Lipunov, V. M.; Kornilov, V. G.; Belinski, A. A.; Shatskiy, N. I.; Tyurina, N. V.; Kuvshinov, D. A.; Balanutsa, P. V.; Chazov, V. V.; Kuznetsov, A.; Zimnukhov, D. S.; Kornilov, M. V.; Sankovich, A. V.; Krylov, A.; Ivanov, K. I.; Chvalaev, O.; Poleschuk, V. A.; Konstantinov, E. N.; Gress, O. A.; Yazev, S. A.; Budnev, N. M.; Krushinski, V. V.; Zalozhnich, I. S.; Popov, A. A.; Tlatov, A. G.; Parhomenko, A. V.; Dormidontov, D. V.; Senik, V.; Yurkov, V. V.; Sergienko, Yu. P.; Varda, D.; Kudelina, I. P.; Castro-Tirado, A. J.; Gorosabel, J.; Sánchez-Ramírez, R.; Jelinek, M.; Tello, J. C.

    2012-04-01

    We present the results of the prompt, early and afterglow optical observations of five γ-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations were made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the Sierra Nevada Observatory and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before the cessation of γ-ray emission, at 113 and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted in two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. A more detailed analysis of GRB 100901A and GRB 100906A, supplemented by Swift data, provides the following results and indicates different origins for the prompt optical radiation in the two bursts. The light-curve patterns and spectral distributions suggest that there is a common production site for the prompt optical and high-energy emission in GRB 100901A. The results of the spectral fits for GRB 100901A in the range from optical to X-ray favour power-law energy distributions and a consistent value of the optical extinction in the host galaxy. GRB 100906A produced a smoothly peaking optical light curve, suggesting that the prompt optical radiation in this GRB originated in a front shock. This is supported by a spectral analysis. We have found that the Amati and Ghirlanda relations are satisfied for GRB 100906A. We obtain an upper limit on the value of the optical extinction on the host of GRB 100906A.

  16. Physics of the GRB 030328 afterglow and its environment

    NASA Astrophysics Data System (ADS)

    Maiorano, E.; Masetti, N.; Palazzi, E.; Savaglio, S.; Rol, E.; Vreeswijk, P. M.; Pian, E.; Price, P. A.; Peterson, B. A.; Jelínek, M.; Amati, L.; Andersen, M. I.; Castro-Tirado, A. J.; Castro Cerón, J. M.; de Ugarte Postigo, A.; Frontera, F.; Fruchter, A. S.; Fynbo, J. P. U.; Gorosabel, J.; Henden, A. A.; Hjorth, J.; Jensen, B. L.; Klose, S.; Kouveliotou, C.; Masi, G.; Møller, P.; Nicastro, L.; Ofek, E. O.; Pandey, S. B.; Rhoads, J.; Tanvir, N. R.; Wijers, R. A. M. J.; van den Heuvel, E. P. J.

    2006-08-01

    Aims.To investigate the physical nature of the afterglow emission. We report on the photometric, spectroscopic and polarimetric observations of the optical afterglow of Gamma-Ray Burst (GRB) 030328 detected by HETE-2.Methods.Photometric, spectroscopic and polarimetric monitoring of the optical afterglow.Results.Photometry, collected at 7 different telescopes, shows that a smoothly broken powerlaw decay, with indices α1 = 0.76 ± 0.03, α2 = 1.50 ± 0.07 and a break at tb = 0.48 ± 0.03 days after the GRB, provides the best fit of the optical afterglow decline. This shape is interpreted as due to collimated emission, for which we determine a jet opening angle θ_jet ˜ 3.2 °. An achromatic bump starting around ~0.2 d after the GRB is possibly marginally detected in the optical light curves. Optical spectroscopy shows the presence of two rest-frame ultraviolet metal absorption systems at z = 1.5216 ± 0.0006 and at z = 1.295 ± 0.001, the former likely associated with the GRB host galaxy. Analysis of the absorption lines at z = 1.5216 suggests that the host of this GRB may be a Damped Lyman-α Absorber. The optical V-band afterglow appears polarized, with P = (2.4 ± 0.6)% and θ = 170° ± 7°, suggesting an asymmetric blastwave expansion. An X-ray-to-optical spectral flux distribution of the GRB 030328 afterglow was obtained at 0.78 days after the GRB and fitted using a broken powerlaw, with an optical spectral slope β_opt = 0.47 ± 0.15, and an X-ray slope βX = 1.0 ± 0.2.Conclusions.The discussion of the results in the context of the "fireball model" shows that the preferred scenario for this afterglow is collimated structured jet with fixed opening angle in a homogeneous medium.

  17. Rapid GRB Afterglow Response With SARA

    NASA Astrophysics Data System (ADS)

    Garimella, K. V.; Homewood, A. L.; Hartmann, D. H.; Riddle, C.; Fuller, S.; Manning, A.; McIntyre, T.; Henson, G.

    2006-05-01

    The Clemson GRB Follow-Up program utilizes the SARA 0.9-m telescope to observe optical afterglows of Gamma Ray Bursts. SARA is not yet robotic; it operates under direct and Target-of-Opportunity (ToO) interrupt modes. To facilitate rapid response and timely reporting of data analysis results, we developed a software suite that operates in two phases: first, to notify observers of a burst and assist in data collection, and second, to quickly analyze the images.

  18. Short GRB Prompt and Afterglow Correlations

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2007-01-01

    The Swift data set on short GRBs has now grown large enough to study correlations of key parameters. The goal is to compare long and short bursts to better understand similarities and differences in the burst origins. In this study we consider the both prompt and afterglow fluxes. It is found that the optical, X-ray and gamma-ray emissions are linearly correlated - stronger bursts tend to have brighter afterglows, and bursts with brighter X-ray afterglow tend to have brighter optical afterglow. Both the prompt and afterglow fluxes are, on average, lower for short bursts than for long. Although there are short GRBs with undetected optical emission, there is no evidence for "dark" short bursts with anomalously low opt/X ratios. The weakest short bursts have a low X-ray/gamma-ray ratio.

  19. The distribution of equivalent widths in long GRB afterglow spectra

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, A.; Fynbo, J. P. U.; Thöne, C. C.; Christensen, L.; Gorosabel, J.; Milvang-Jensen, B.; Schulze, S.; Jakobsson, P.; Wiersema, K.; Sánchez-Ramírez, R.; Leloudas, G.; Zafar, T.; Malesani, D.; Hjorth, J.

    2012-12-01

    Context. The extreme brightness of gamma-ray burst (GRB) afterglows and their simple spectral shape make them ideal beacons to study the interstellar medium of their host galaxies through absorption line spectroscopy at almost any redshift. Aims: We describe the distribution of rest-frame equivalent widths (EWs) of the most prominent absorption features in GRB afterglow spectra, providing the means to compare individual spectra to the sample and identify its peculiarities. Methods: Using 69 low-resolution GRB afterglow spectra, we conduct a study of the rest-frame EWs distribution of features with an average rest-frame EW larger than 0.5 Å. To compare an individual GRB with the sample, we develop EW diagrams as a graphical tool, and we give a catalogue with diagrams for the 69 spectra. We introduce a line strength parameter (LSP) that allows us to quantify the strength of the absorption features in a GRB spectrum as compared to the sample by a single number. Using the distributions of EWs of single-species features, we derive the distribution of their column densities by a curve of growth (CoG) fit. Results: We find correlations between the LSP and the extinction of the GRB, the UV brightness of the host galaxies and the neutral hydrogen column density. However, we see no significant evolution of the LSP with the redshift. There is a weak correlation between the ionisation of the absorbers and the energy of the GRB, indicating that, either the GRB event is responsible for part of the ionisation, or that galaxies with high-ionisation media produce more energetic GRBs. Spectral features in GRB spectra are, on average, 2.5 times stronger than those seen in QSO intervening damped Lyman-α (DLA) systems and slightly more ionised. In particular we find a larger excess in the EW of C ivλλ1549 relative to QSO DLAs, which could be related to an excess of Wolf-Rayet stars in the environments of GRBs. From the CoG fitting we obtain an average number of components in the

  20. Radio observations of GRB 100418a: Test of an energy injection model explaining long-lasting GRB afterglows

    SciTech Connect

    Moin, A.; Wang, Z.; Chandra, P.; Miller-Jones, J. C. A.; Tingay, S. J.; Reynolds, C.; Taylor, G. B.; Frail, D. A.; Phillips, C. J.

    2013-12-20

    We present the results of our radio observational campaign of gamma-ray burst (GRB) 100418a, for which we used the Australia Telescope Compact Array, the Very Large Array, and the Very Long Baseline Array. GRB 100418a was a peculiar GRB with unusual X-ray and optical afterglow profiles featuring a plateau phase with a very shallow rise. This observed plateau phase was believed to be due to a continued energy injection mechanism that powered the forward shock, giving rise to an unusual and long-lasting afterglow. The radio afterglow of GRB 100418a was detectable several weeks after the prompt emission. We conducted long-term monitoring observations of the afterglow and attempted to test the energy injection model advocating that the continuous energy injection is due to shells of material moving at a wide range of Lorentz factors. We obtained an upper limit of γ < 7 for the expansion rate of the GRB 100418a radio afterglow, indicating that the range-of-Lorentz factor model could only be applicable for relatively slow-moving ejecta. A preferred explanation could be that continued activity of the central engine may have powered the long-lasting afterglow.

  1. MAGIC upper limits on the GRB 090102 afterglow

    NASA Astrophysics Data System (ADS)

    Aleksić, J.; Ansoldi, S.; Antonelli, L. A.; Antoranz, P.; Babic, A.; de Almeida, U. Barres; Barrio, J. A.; González, J. Becerra; Bednarek, W.; Berger, K.; Bernardini, E.; Biland, A.; Blanch, O.; Bock, R. K.; Boller, A.; Bonnefoy, S.; Bonnoli, G.; Borracci, F.; Bretz, T.; Carmona, E.; Carosi, A.; Fidalgo, D. Carreto; Colin, P.; Colombo, E.; Contreras, J. L.; Cortina, J.; Cossio, L.; Covino, S.; Da Vela, P.; Dazzi, F.; De Angelis, A.; De Caneva, G.; De Lotto, B.; Mendez, C. Delgado; Doert, M.; Domínguez, A.; Prester, D. Dominis; Dorner, D.; Doro, M.; Eisenacher, D.; Elsaesser, D.; Farina, E.; Ferenc, D.; Fonseca, M. V.; Font, L.; Frantzen, K.; Fruck, C.; López, R. J. García; Garczarczyk, M.; Terrats, D. Garrido; Gaug, M.; Giavitto, G.; Godinović, N.; Munoz, A. González; Gozzini, S. R.; Hadamek, A.; Hadasch, D.; Herrero, A.; Hose, J.; Hrupec, D.; Idec, W.; Kadenius, V.; Knoetig, M. L.; Krähenbühl, T.; Krause, J.; Kushida, J.; Barbera, A. La; Lelas, D.; Lewandowska, N.; Lindfors, E.; Lombardi, S.; López-Coto, R.; López, M.; López-Oramas, A.; Lorenz, E.; Lozano, I.; Makariev, M.; Mallot, K.; Maneva, G.; Mankuzhiyil, N.; Mannheim, K.; Maraschi, L.; Marcote, B.; Mariotti, M.; Martínez, M.; Masbou, J.; Mazin, D.; Menzel, U.; Meucci, M.; Miranda, J. M.; Mirzoyan, R.; Moldón, J.; Moralejo, A.; Munar-Adrover, P.; Nakajima, D.; Niedzwiecki, A.; Nilsson, K.; Nowak, N.; Orito, R.; Overkemping, A.; Paiano, S.; Palatiello, M.; Paneque, D.; Paoletti, R.; Paredes, J. M.; Partini, S.; Persic, M.; Prada, F.; Moroni, P. G. Prada; Prandini, E.; Preziuso, S.; Puljak, I.; Reichardt, I.; Reinthal, R.; Rhode, W.; Ribó, M.; Rico, J.; Garcia, J. Rodriguez; Rügamer, S.; Saggion, A.; Saito, K.; Saito, T.; Salvati, M.; Satalecka, K.; Scalzotto, V.; Scapin, V.; Schultz, C.; Schweizer, T.; Shore, S. N.; Sillanpää, A.; Sitarek, J.; Snidaric, I.; Sobczynska, D.; Spanier, F.; Stamatescu, V.; Stamerra, A.; Storz, J.; Sun, S.; Surić, T.; Takalo, L.; Tavecchio, F.; Temnikov, P.; Terzić, T.; Tescaro, D.; Teshima, M.; Thaele, J.; Tibolla, O.; Torres, D. F.; Toyama, T.; Treves, A.; Uellenbeck, M.; Vogler, P.; Wagner, R. M.; Weitzel, Q.; Zandanel, F.; Zanin, R.; Bouvier, A.; Hayashida, M.; Tajima, H.; Longo, F.

    2014-02-01

    Indications of a GeV component in the emission from gamma-ray bursts (GRBs) are known since the Energetic Gamma-Ray Experiment Telescope observations during the 1990s and they have been confirmed by the data of the Fermi satellite. These results have, however, shown that our understanding of GRB physics is still unsatisfactory. The new generation of Cherenkov observatories and in particular the MAGIC telescope, allow for the first time the possibility to extend the measurement of GRBs from several tens up to hundreds of GeV energy range. Both leptonic and hadronic processes have been suggested to explain the possible GeV/TeV counterpart of GRBs. Observations with ground-based telescopes of very high energy (VHE) photons (E > 30 GeV) from these sources are going to play a key role in discriminating among the different proposed emission mechanisms, which are barely distinguishable at lower energies. MAGIC telescope observations of the GRB 090102 (z = 1.547) field and Fermi Large Area Telescope data in the same time interval are analysed to derive upper limits of the GeV/TeV emission. We compare these results to the expected emissions evaluated for different processes in the framework of a relativistic blastwave model for the afterglow. Simultaneous upper limits with Fermi and a Cherenkov telescope have been derived for this GRB observation. The results we obtained are compatible with the expected emission although the difficulties in predicting the HE and VHE emission for the afterglow of this event makes it difficult to draw firmer conclusions. Nonetheless, MAGIC sensitivity in the energy range of overlap with space-based instruments (above about 40 GeV) is about one order of magnitude better with respect to Fermi. This makes evident the constraining power of ground-based observations and shows that the MAGIC telescope has reached the required performance to make possible GRB multiwavelength studies in the VHE range.

  2. Two Early Gamma-ray Bursts Optical Afterglow Detections with TAOS Telescopes--GRB 071010B and GRB 071112C

    SciTech Connect

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

    2009-05-25

    We present on two early detections of GRB afterglows with the Taiwanese-American Occltation Sruvey (TAOS) telescopes. The robotic TAOS system has been devised so that the routine Kuiper Belt Object (KBO) survey is interrupted when a GRB alert is triggered. Our first detection, GRB 071010B was detected by TAOS 62 s after the burst and showed a weak early brightening during the observations. No significant correction with the prompt gamma-ray emission indicated that our optical emission detected is afterglow emission. The second detection of TAOS, GRB 071112C was detected 96 s after the burst, also showed a possible initial raising then followed a steep decay in the R-band light curve.

  3. Two Early Gamma-ray Bursts Optical Afterglow Detections with TAOS Telescopes-GRB 071010B and GRB 071112C

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    We present on two early detections of GRB afterglows with the Taiwanese-American Occltation Sruvey (TAOS) telescopes. The robotic TAOS system has been devised so that the routine Kuiper Belt Object (KBO) survey is interrupted when a GRB alert is triggered. Our first detection, GRB 071010B was detected by TAOS 62 s after the burst and showed a weak early brightening during the observations. No significant correction with the prompt gamma-ray emission indicated that our optical emission detected is afterglow emission. The second detection of TAOS, GRB 071112C was detected 96 s after the burst, also showed a possible initial raising then followed a steep decay in the R-band light curve.

  4. The ultra-long GRB 111209A. II. Prompt to afterglow and afterglow properties

    SciTech Connect

    Stratta, G.; Gendre, B.; Boër, M.; Atteia, J. L.; Coward, D. M.; Howell, E.; De Pasquale, M.; Oates, S.; Klotz, A.; Piro, L.

    2013-12-10

    The 'ultra-long' gamma-ray burst GRB 111209A at redshift z = 0.677 is the longest GRB ever observed thus far, with a rest frame prompt emission duration of ∼4 hr. In order to explain the burst exceptional longevity, a low-metallicity blue supergiant progenitor was invoked. In this article we further constrain the phenomenology and progenitor properties of this peculiar GRB by performing a multiband temporal and spectral analysis of both the prompt and the afterglow emission. We use proprietary and publicly available data from Swift, Konus WIND, XMM-Newton, and TAROT, as well as from other ground-based optical and radio telescopes. We find some peculiar properties that are possibly connected to the exceptional nature of this burst, namely: (1) an unprecedented large optical delay of 410 ± 50 s between the peak time in gamma-rays and the peak time in the optical of a marked multiwavelength flare; (2) multiwavelength prompt emission spectral modeling requires a certain amount of dust in the circumburst environment. The dust produces a rest frame visual extinction of A{sub V} = 0.3-1.5 mag, and may undergo destruction at late times; and (3) we detect the presence of a hard spectral extra power-law component at the end of the X-ray steep steep decay phase and before the start of the X-ray afterglow, which has never been revealed thus far in past GRBs. The optical afterglow shows more usual properties; it has a flux power-law decay with an index of 1.6 ± 0.1 and a late rebrightening feature observed at ∼1.1 the day after the first Burst Alert Telescope trigger. We discuss our findings in the context of several possible interpretations that have been given thus far of the complex multiband GRB phenomenology and propose a binary channel formation for the blue supergiant progenitor.

  5. GRB 030329: 3 years of radio afterglow monitoring.

    PubMed

    van der Horst, A J; Kamble, A; Wijers, R A M J; Resmi, L; Bhattacharya, D; Rol, E; Strom, R; Kouveliotou, C; Oosterloo, T; Ishwara-Chandra, C H

    2007-05-15

    Radio observations of gamma-ray burst (GRB) afterglows are essential for our understanding of the physics of relativistic blast waves, as they enable us to follow the evolution of GRB explosions much longer than the afterglows in any other wave band. We have performed a 3-year monitoring campaign of GRB 030329 with the Westerbork Synthesis Radio Telescopes and the Giant Metrewave Radio Telescope. Our observations, combined with observations at other wavelengths, have allowed us to determine the GRB blast wave physical parameters, such as the total burst energy and the ambient medium density, as well as to investigate the jet nature of the relativistic outflow. Further, by modelling the late-time radio light curve of GRB 030329, we predict that the Low-Frequency Array (30-240 MHz) will be able to observe afterglows of similar GRBs, and constrain the physics of the blast wave during its non-relativistic phase. PMID:17293318

  6. Five Years of Multi-frequency Monitoring of GRB030329 Afterglow Using the GMRT and WSRT

    NASA Astrophysics Data System (ADS)

    Kamble, Atish; van der Horst, A. J.; Bhattacharya, D.; Wijers, Ralph; Chandra, C. H. Ishwara; Resmi, L.; Rol, Evert; Kouveliotou, Chryssa; Strom, R.

    2009-05-01

    GRB 030329 displayed one of the brightest optical afterglows ever. We have followed the radio afterglow of GRB 030329 for over 5 years using the GMRT and WSRT at low radio frequencies. This is the longest as well as the lowest frequency follow up of any GRB afterglow ever. Radio observations of a GRB afterglow provide a unique probe of the physics of the blast wave at late times, when the expansion of the fireball slows down to non-relativistic speeds. Our GMRT-WSRT observations suggest that the afterglow of GRB030329 entered the non-relativistic phase around 60 days after the burst. The estimate of the fireball energy content, ~1051 erg, in this near-isotropic phase is much less susceptible to the collimation-related uncertainties arising in the relativistic phase. We have also been closely monitoring the evolution of the afterglow to look for possible signatures of emission from a counter jet, but no conclusive evidence has so far been found.

  7. X-ray flares, plateaus and chromatic breaks of GRB afterglows from up-scattered forward-shock emission

    NASA Astrophysics Data System (ADS)

    Panaitescu, A.

    2008-01-01

    Scattering of the forward-shock synchrotron emission by a relativistic outflow located behind the leading blast wave may produce an X-ray emission brighter than that coming directly from the forward shock and may explain four features displayed by Swift X-ray afterglows: flares, plateaus (slow decays), chromatic light-curve breaks and fast post-plateau decays. For a cold scattering outflow, the reflected flux overshines the primary one if the scattering outflow is nearly baryon-free and highly relativistic. These two requirements can be relaxed if the scattering outflow is energized by weak internal shocks, so that the incident forward-shock photons are also inverse-Compton scattered, in addition to bulk scattering. Sweeping-up of the photons left behind by the forward shock naturally yields short X-ray flares. Owing to the boost in photon energy produced by bulk scattering, the reflected emission is more likely to overshine that coming directly from the forward shock at higher photon energies, yielding light-curve plateaus and breaks that appear only in the X-ray. The brightness, shape and decay of the X-ray light-curve plateau depend on the radial distribution of the scatterer's Lorentz factor and mass flux. Chromatic X-ray light-curve breaks and sharp post-plateau decays cannot be accommodated by the direct forward-shock emission and argue in favour of the scattering-outflow model proposed here. On the other hand, the X-ray afterglows without plateaus, those with achromatic breaks and those with very long lived power-law decays are more naturally accommodated by the standard forward-shock model. Thus, the diversity of X-ray light curves arises from the interplay of the scattered and direct forward-shock emissions.

  8. The bright optical flash and afterglow from the gamma-ray burst GRB 130427A.

    PubMed

    Vestrand, W T; Wren, J A; Panaitescu, A; Wozniak, P R; Davis, H; Palmer, D M; Vianello, G; Omodei, N; Xiong, S; Briggs, M S; Elphick, M; Paciesas, W; Rosing, W

    2014-01-01

    The optical light generated simultaneously with x-rays and gamma rays during a gamma-ray burst (GRB) provides clues about the nature of the explosions that occur as massive stars collapse. We report on the bright optical flash and fading afterglow from powerful burst GRB 130427A. The optical and >100-megaelectron volt (MeV) gamma-ray flux show a close correlation during the first 7000 seconds, which is best explained by reverse shock emission cogenerated in the relativistic burst ejecta as it collides with surrounding material. At later times, optical observations show the emergence of emission generated by a forward shock traversing the circumburst environment. The link between optical afterglow and >100-MeV emission suggests that nearby early peaked afterglows will be the best candidates for studying gamma-ray emission at energies ranging from gigaelectron volts to teraelectron volts. PMID:24263131

  9. Was the X-ray Afterglow of GRB 970815 Detected?

    NASA Astrophysics Data System (ADS)

    Mirabal, N.; Halpern, J. P.; Gotthelf, E. V.; Mukherjee, R.

    2004-09-01

    GRB 970815 was a well-localized gamma-ray burst (GRB) detected by the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer (RXTE) for which no afterglow was identified despite follow-up ASCA and ROSAT pointings and optical imaging to limiting magnitude R > 23. While an X-ray source, AX/RX J1606.8+8130, was detected just outside the ASM error box, it was never associated with the GRB because it was not clearly fading and because no optical afterglow was ever discovered. We recently made deep optical observations of the AX/RX J1606.8+8130 position, which is blank to a limit of V > 24.3 and I > 24.0, implying an X-ray-to-optical flux ratio fX/fV > 500. In view of this extreme limit, we analyze and reevaluate the ASCA and ROSAT data and conclude that the X-ray source AX/RX J1606.8+8130 was indeed the afterglow of GRB 970815, which corresponds to an optically ``dark'' GRB. Alternatively, if AX/RX J1608+8130 is discovered to be a persistent source, then it could be associated with EGRET source 3EG J1621+8203, whose error box includes this position.

  10. 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.; Klose, S.; Kupcu-Yoldas, A.; McBreen, S.; Olivares, E.; Pierini, D.; Rau, A.; Rossi, A.; Nardini, M.; Nicuesa Guelbenzu, A.; Sudilovsky, V.; Updike, A. C.

    2011-01-01

    The afterglows and host galaxies of long gamma-ray bursts (GRBs) offer unique opportunities to study star-forming galaxies in the high-z Universe, Until recently, however. the information inferred from GRB follow-up observations was mostly limited to optically bright afterglows. biasing all demographic studies against sight-lines that contain large amounts of dust. Aims. Here we present afterglow and host observations for a sample of bursts that are exemplary of previously missed ones because of high visual extinction (A(sub v) (Sup GRB) approx > 1 mag) along the sight-line. This facilitates an investigation of the properties, geometry and location of the absorbing dust of these poorly-explored host galaxies. and a comparison to hosts from optically-selected samples. Methods. This work is based on GROND optical/NIR and Swift/XRT X-ray observations of the afterglows, and multi-color imaging for eight GRB hosts. The afterglow and galaxy spectral energy distributions yield detailed insight into physical properties such as the dust and metal content along the GRB sight-line as well as galaxy-integrated characteristics like the host's stellar mass, luminosity. color-excess and star-formation rate. Results. For the eight afterglows considered in this study we report for the first time the redshift of GRBs 081109 (z = 0.97S7 +/- 0.0005). and the visual extinction towards GRBs 0801109 (A(sub v) (Sup GRB) = 3.4(sup +0.4) (sub -0.3) mag) and l00621A (A(sub v) (Sup GRB) = 3.8 +/- 0.2 mag), which are among the largest ever derived for GRB afterglows. Combined with non-extinguished GRBs. there is a strong anti-correlation between the afterglow's metals-to-dust ratio and visual extinction. The hosts of the dustiest afterglows are diverse in their properties, but on average redder(((R - K)(sub AB)) approximates 1.6 mag), more luminous ( approximates 0.9 L (sup *)) and massive ((log M(sup *) [M(solar]) approximates 9.8) than the hosts of optically-bright events. We hence probe

  11. Circular polarization in the optical afterglow of GRB 121024A

    NASA Astrophysics Data System (ADS)

    Wiersema, K.; Covino, S.; Toma, K.; van der Horst, A. J.; Varela, K.; Min, M.; Greiner, J.; Starling, R. L. C.; Tanvir, N. R.; Wijers, R. A. M. J.; Campana, S.; Curran, P. A.; Fan, Y.; Fynbo, J. P. U.; Gorosabel, J.; Gomboc, A.; Götz, D.; Hjorth, J.; Jin, Z. P.; Kobayashi, S.; Kouveliotou, C.; Mundell, C.; O'Brien, P. T.; Pian, E.; Rowlinson, A.; Russell, D. M.; Salvaterra, R.; di Serego Alighieri, S.; Tagliaferri, G.; Vergani, S. D.; Elliott, J.; Fariña, C.; Hartoog, O. E.; Karjalainen, R.; Klose, S.; Knust, F.; Levan, A. J.; Schady, P.; Sudilovsky, V.; Willingale, R.

    2014-05-01

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets.

  12. Circular polarization in the optical afterglow of GRB 121024A.

    PubMed

    Wiersema, K; Covino, S; Toma, K; van der Horst, A J; Varela, K; Min, M; Greiner, J; Starling, R L C; Tanvir, N R; Wijers, R A M J; Campana, S; Curran, P A; Fan, Y; Fynbo, J P U; Gorosabel, J; Gomboc, A; Götz, D; Hjorth, J; Jin, Z P; Kobayashi, S; Kouveliotou, C; Mundell, C; O'Brien, P T; Pian, E; Rowlinson, A; Russell, D M; Salvaterra, R; di Serego Alighieri, S; Tagliaferri, G; Vergani, S D; Elliott, J; Fariña, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovsky, V; Willingale, R

    2014-05-01

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets. PMID:24776800

  13. Evidence for an Early High-Energy Afterglow Observed with BATSE from GRB 980923

    NASA Technical Reports Server (NTRS)

    Giblin, T. W.; vanParadijs, J.; Kouveliotou, C.; Connaughton, V.; Wijers, R. A. M. J.; Briggs, M. S.; Preece, R. D.; Fishman, G. J.

    1999-01-01

    In this Letter, we present the first evidence in the BATSE data for a prompt high-energy (25-300 keV) afterglow component from a gamma-ray burst, GRB 980923. The event consists of rapid variability lasting approximately 40 s followed by a smooth power-law emission tail lasting approximately 400 s. An abrupt change in spectral shape is found when the tail becomes noticeable. Our analysis reveals that the spectral evolution in the tail of the burst mimics that of a cooling synchrotron spectrum, similar to the spectral evolution of the low-energy afterglows for gamma-ray bursts. This evidence for a separate emission component is consistent with the internal-external shock scenario in the relativistic fireball picture. In particular, it illustrates that the external shocks can be generated during the gamma-ray emission phase, as in the case of GRB 990123.

  14. The afterglow of GRB 130427A from 1 to 10{sup 16} GHz

    SciTech Connect

    Perley, D. A.; Cenko, S. B.; Corsi, A.; Tanvir, N. R.; Wiersema, K.; Levan, A. J.; Kann, D. A.; Greiner, J.; Sonbas, E.; Zheng, W.; Clubb, K. I.; Zhao, X.-H.; Bai, J.-M.; Chang, L.; Bremer, M.; Castro-Tirado, A. J.; Fruchter, A.; Göğüş, E.; Güver, T.; and others

    2014-01-20

    We present multiwavelength observations of the afterglow of GRB 130427A, the brightest (in total fluence) gamma-ray burst (GRB) of the past 29 yr. Optical spectroscopy from Gemini-North reveals the redshift of the GRB to be z = 0.340, indicating that its unprecedented brightness is primarily the result of its relatively close proximity to Earth; the intrinsic luminosities of both the GRB and its afterglow are not extreme in comparison to other bright GRBs. We present a large suite of multiwavelength observations spanning from 300 s to 130 days after the burst and demonstrate that the afterglow shows relatively simple, smooth evolution at all frequencies, with no significant late-time flaring or rebrightening activity. The entire data set from 1 GHz to 10 GeV can be modeled as synchrotron emission from a combination of reverse and forward shocks in good agreement with the standard afterglow model, providing strong support to the applicability of the underlying theory and clarifying the nature of the GeV emission observed to last for minutes to hours following other very bright GRBs. A tenuous, wind-stratified circumburst density profile is required by the observations, suggesting a massive-star progenitor with a low mass-loss rate, perhaps due to low metallicity. GRBs similar in nature to GRB 130427A, inhabiting low-density media and exhibiting strong reverse shocks, are probably not uncommon but may have been difficult to recognize in the past owing to their relatively faint late-time radio emission; more such events should be found in abundance by the new generation of sensitive radio and millimeter instruments.

  15. 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.

  16. Theoretical Implications of Optical and X-ray Observations of Swift GRB Afterglows

    SciTech Connect

    Panaitescu, A.

    2007-08-21

    The Swift satellite has measured the X-ray emission of GRB afterglows starting from the burst epoch, filling thus a gap of about 2 decades in the temporal coverage of X-ray afterglows previously achieved. At the same time, the accurate localizations provided by Swift and their rapid dissemination has allowed ground-based telescopes to monitor the optical afterglow emission at comparably early epochs. Such optical and X-ray observations allows us to test more thoroughly the basic predictions of the relativistic blast-wave. Perhaps it is not an understatement to say that there were more surprises than anyone expected. A majority of Swift X-ray afterglows exhibit a slow-decay phase from 500 s to about 1 h after trigger, which indicates a long-lived process of energy injection into the blast-wave. At around 1 h, the X-ray decay steepens, indicating the end of significant energy addition to the forward shock. This steeper decay is consistent with the blast-wave model expectations but the 1 h break is, generally, not accompanied by a steepening of the optical light-curve, which indicates that forward-shock microphysical parameters are not constant, as was previously assumed and allowed by afterglow observations. A subsequent steepening of the X-ray light-curve decay, at about 1 d, was observed by Swift for only a few afterglows. This second break appears consistent with originating from the blast-wave collimation (a jet), but a better optical coverage is required to test that it is, indeed, a jet-break. Although the jet model has been the subject of many tens of papers, pre-Swift optical and X-ray observations of GRB afterglows have provided little proof that the 1 d optical breaks observed in a dozen afterglows are consistent with the expectations for a collimated outflow.

  17. Complicated variations in the early optical afterglow of GRB 090726

    NASA Astrophysics Data System (ADS)

    Šimon, V.; Polášek, C.; Jelínek, M.; Hudec, R.; Štrobl, J.

    2010-02-01

    Aims: We report on the detection of an early rising phase of optical afterglow (OA) of a long GRB 090726. We resolve a complicated profile of the optical light curve. We also investigate the relation of the optical and X-ray emission of this event. Methods: We made use of the optical photometry of this OA obtained by the 0.5 m telescope of AI AS CR, supplemented by the data obtained by other observers, and the X-ray Swift/XRT data. Results: The optical emission peaked at ˜17.5 mag(R) at t - T0 ≈ 500 s. We find a complex profile of the light curve during the early phase of this OA: an approximately power-law rise, a rapid transition to a plateau, a weak flare superimposed on the center of this plateau, and a slowly steepening early decline followed by a power-law decay. We discuss several possibilities for explaining the short flare on the flat top of the optical light curve at t-T0 ≈ 500 s. Activity of the central engine is favored, although reverse shock cannot be ruled out. We show that power-law outflow with Θ_obs/Θc > 2.5 is the best case for the OA of GRB 090726. The initial Lorentz factor is Γ0 ≈ 230-530 in the case of propagation of the blast wave in a homogeneous medium, while propagation of this wave in a wind environment gives Γ0 ≈ 80-300. The value of Γ0 in GRB 090726 thus falls into the lower half of the range observed in GRBs and it may even lie on the lower end. We also show that both the optical and X-ray emission decayed simultaneously and that the spectral profile from X-ray to the optical band did not vary. This is true for both the time periods before and after the break in the X-ray light curve. This break can be regarded as achromatic. The available data show that neither the dust nor the gaseous component of the circumburst medium underwent any evolution during the decay of this OA, that is, after t-T0 < 3000 s. We also show that this OA belongs to the least luminous ones in the phase of its power-law decay, corresponding to what

  18. The Late Afterglow and Host Galaxy of GRB 990712.

    PubMed

    Hjorth; Holland; Courbin; Dar; Olsen; Scodeggio

    2000-05-10

    We present deep Hubble Space Telescope (HST) imaging, as well as ground-based imaging and spectroscopy, of the optical afterglow associated with the long-duration gamma-ray burst GRB 990712 and its host galaxy. The data were obtained 48-123 days after the burst occurred. The magnitudes of the host (R=21.9, V=22.5) and optical afterglow (R=25.4, V=25.8, 47.7 days after the burst) favor a scenario in which the optical light follows a pure power-law decay with an index of alpha approximately -1.0. We find no evidence for a contribution from a supernova like SN 1998bw. This suggests that either there are multiple classes of long-duration gamma-ray bursts or that the peak luminosity of the supernova was more than 1.5 mag fainter than SN 1998bw. The HST images and EFOSC2 spectra indicate that the gamma-ray burst was located in a bright, extended feature (possibly a star-forming region) 1.4 kpc from the nucleus of a 0.2L*B galaxy at z=0.434, possibly a Seyfert 2 galaxy. The late-time afterglow and host galaxy of GRB 990712 bear some resemblance to those of GRB 970508. PMID:10813669

  19. 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.

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

    SciTech Connect

    Sultana, J.; Kazanas, D.

    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%) 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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 pk ~ mec 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%) decrease in Γ at a radius that is smaller (depending on conditions) than the deceleration radius RD . 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 ~mp /me than that of the prompt emission. If the radius at which this slow-down occurs is significantly smaller than RD , the RBW internal energy continues to drive the RBW expansion at a constant (new) Γ and its X-ray luminosity remains constant until RD 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 ~= RD , 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 ~= RD , thus providing novel insights into GRB phenomenology.

  2. 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.

  3. Optical and NIR observations of the afterglow of GRB 020813

    NASA Astrophysics Data System (ADS)

    Covino, S.; Malesani, D.; Tavecchio, F.; Antonelli, L. A.; Arkharov, A.; Di Paola, A.; Fugazza, D.; Ghisellini, G.; Larionov, V.; Lazzati, D.; Mannucci, F.; Masetti, N.; Barrena, R.; Benetti, S.; Castro-Tirado, A. J.; Di Serego Alighieri, S.; Fiore, F.; Frontera, F.; Fruchter, A.; Ghinassi, F.; Gladders, M.; Hall, P. B.; Israel, G. L.; Klose, S.; Magazzù, A.; Palazzi, E.; Pedani, M.; Pian, E.; Romano, P.; Stefanon, M.; Stella, L.

    2003-06-01

    We present optical and near-infrared (NIR) photometry of the bright afterglow of GRB 020813. Our data span from 3 hours to 4 days after the GRB event. A rather sharp achromatic break is present in the light curve, 14 hours after the trigger. In the framework of jetted fireballs, this break corresponds to a jet half-opening angle of 1.9degr +/-0.2degr , the smallest value ever inferred for a GRB. We discuss our results in the framework of currently available models, and find that they have problems in explaining the joint temporal and spectral properties, and in particular the slow decay before the break. Based on observations partly made with ESO telescopes at the Paranal Observatories under programme Id 69.D-0461 and with the Italian TNG telescope under programme TAC 8_01(47).

  4. CALORIMETRY OF GRB 030329: SIMULTANEOUS MODEL FITTING TO THE BROADBAND RADIO AFTERGLOW AND THE OBSERVED IMAGE EXPANSION RATE

    SciTech Connect

    Mesler, Robert A.; Pihlstroem, Ylva M.

    2013-09-01

    We perform calorimetry on the bright gamma-ray burst GRB 030329 by fitting simultaneously the broadband radio afterglow and the observed afterglow image size to a semi-analytic MHD and afterglow emission model. Our semi-analytic method is valid in both the relativistic and non-relativistic regimes, and incorporates a model of the interstellar scintillation that substantially effects the broadband afterglow below 10 GHz. The model is fitted to archival measurements of the afterglow flux from 1 day to 8.3 yr after the burst. Values for the initial burst parameters are determined and the nature of the circumburst medium is explored. Additionally, direct measurements of the lateral expansion rate of the radio afterglow image size allow us to estimate the initial Lorentz factor of the jet.

  5. Optical and X-Ray Observations of GRB 060526: A Complex Afterglow Consistent with an Achromatic Jet Break

    NASA Technical Reports Server (NTRS)

    Dai, X.; Halpern, J. P.; Morgan, N. D.; Armstrong, E.; Mirabal, N.; Haislip. J. B.; Reichart, D. E.; Stanek, K. Z.

    2007-01-01

    We obtained 98 R-band and 18 B, r', i' images of the optical afterglow of GRB 060526 (z = 3.21) with the MDM 1.3 m, 2.4 m, and the PROMPT telescopes at CTIO over the five nights following the burst trigger. Combining these data with other optical observations reported in GCN and the Swift XRT observations, we compare the optical and X-ray afterglow light curves of GRB 060526. Both the optical and X-ray afterglow light curves show rich features, such as flares and breaks. The densely sampled optical observations provide very good coverage at T > 10(exp 4) s. We observed a break at 2.4 x 10(exp 5) sin the optical afterglow light curve. Compared with the X-ray afterglow light curve, the break is consistent with an achromatic break supporting the beaming models of GRBs. However, the prebreak and postbreak temporal decay slopes are difficult to explain in simple afterglow models. We estimated a jet angle of theta(sub j) approx. 7deg and a prompt emission size of R(sub prompt) approx. 2 x 10(exp 14) cm. In addition, we detected several optical flares with amplitudes of (Delta)m approx. 0.2,0.6, and 0.2 mag. The X-ray afterglows detected by Swift have shown complicated decay patterns. Recently, many well-sampled optical afterglows also show decays with flares and multiple breaks. GRB 060526 provides an additional case of such a complex, well-observed optical afterglow. The accumulated well-sampled afterglows indicate that most of the optical afterglows are complex.

  6. Optical and near-infrared observations of the GRB020405 afterglow

    NASA Astrophysics Data System (ADS)

    Masetti, N.; Palazzi, E.; Pian, E.; Simoncelli, A.; Hunt, L. K.; Maiorano, E.; Levan, A.; Christensen, L.; Rol, E.; Savaglio, S.; Falomo, R.; Castro-Tirado, A. J.; Hjorth, J.; Delsanti, A.; Pannella, M.; Mohan, V.; Pandey, S. B.; Sagar, R.; Amati, L.; Burud, I.; Castro Cerón, J. M.; Frontera, F.; Fruchter, A. S.; Fynbo, J. P. U.; Gorosabel, J.; Kaper, L.; Klose, S.; Kouveliotou, C.; Nicastro, L.; Pedersen, H.; Rhoads, J.; Salamanca, I.; Tanvir, N.; Vreeswijk, P. M.; Wijers, R. A. M. J.; van den Heuvel, E. P. J.

    2003-06-01

    We report on photometric, spectroscopic and polarimetric monitoring of the optical and near-infrared (NIR) afterglow of GRB020405. Ground-based optical observations, performed with 8 different telescopes, started about 1 day after the high-energy prompt event and spanned a period of ~ 10 days; the addition of archival HST data extended the coverage up to ~ 150 days after the GRB. We report the first detection of the afterglow in NIR bands. The detection of Balmer and oxygen emission lines in the optical spectrum of the host galaxy indicates that the GRB is located at redshift z =0.691. Fe II and Mg II absorption systems are detected at z= 0.691 and at z = 0.472 in the afterglow optical spectrum. The latter system is likely caused by absorbing clouds in the galaxy complex located ~ 2'' southwest of the GRB020405 host. Hence, for the first time, the galaxy responsible for an intervening absorption line system in the spectrum of a GRB afterglow is spectroscopically identified. Optical and NIR photometry of the afterglow indicates that, between 1 and 10 days after the GRB, the decay in all bands is consistent with a single power law of index alpha = 1.54+/- 0.06. The late-epoch VLT J-band and HST optical points lie above the extrapolation of this power law, so that a plateau (or ``bump") is apparent in the VRIJ light curves at 10-20 days after the GRB. The light curves at epochs later than day ~ 20 after the GRB are consistent with a power-law decay with index alpha ' = 1.85+/- 0.15. While other authors have proposed to reproduce the bump with the template of the supernova (SN) 1998bw, considered the prototypical ``hypernova'', we suggest that it can also be modeled with a SN having the same temporal profile as the other proposed hypernova SN2002ap, but 1.3 mag brighter at peak, and located at the GRB redshift. Alternatively, a shock re-energization may be responsible for the rebrightening. A single polarimetric R-band measurement shows that the afterglow is polarized

  7. THE LATE PEAKING AFTERGLOW OF GRB 100418A

    SciTech Connect

    Marshall, F. E.; Holland, S. T.; Sakamoto, T.; Antonelli, L. A.; Burrows, D. N.; Siegel, M. H.; Covino, S.; Fugazza, D.; De Pasquale, M.; Oates, S. R.; Evans, P. A.; O'Brien, P. T.; Osborne, J. P.; Pagani, C.; Liang, E. W.; Wu, X. F.; Zhang, B.

    2011-02-01

    GRB 100418A is a long gamma-ray burst (GRB) at redshift z = 0.6235 discovered with the Swift Gamma-ray Burst Explorer with unusual optical and X-ray light curves. After an initial short-lived, rapid decline in X-rays, the optical and X-ray light curves observed with Swift are approximately flat or rising slightly out to at least {approx}7 x 10{sup 3} s after the trigger, peak at {approx}5 x 10{sup 4} s, and then follow an approximately power-law decay. Such a long optical plateau and late peaking is rarely seen in GRB afterglows. Observations with Rapid Eye Mount during a gap in the Swift coverage indicate a bright optical flare at {approx}2.5 x 10{sup 4} s. The long plateau phase of the afterglow is interpreted using either a model with continuous injection of energy into the forward shock of the burst or a model in which the jet of the burst is viewed off-axis. In both models the isotropic kinetic energy in the late afterglow after the plateau phase is {>=}10{sup 2} times the 10{sup 51} erg of the prompt isotropic gamma-ray energy release. The energy injection model is favored because the off-axis jet model would require the intrinsic T{sub 90} for the GRB jet viewed on-axis to be very short, {approx}10 ms, and the intrinsic isotropic gamma-ray energy release and the true jet energy to be much higher than the typical values of known short GRBs. The non-detection of a jet break up to t {approx} 2 x 10{sup 6} s indicates a jet half-opening angle of at least {approx}14{sup 0}, and a relatively high-collimation-corrected jet energy of E{sub jet} {>=} 10{sup 52} erg.

  8. Evidence for an Early High-Energy Afterglow Observed with BATSE from GRB980923

    NASA Technical Reports Server (NTRS)

    Giblin, Tim; vanParadijs, Jan; Kouveliotou, Chryssa; Connaughton, Valerie; Wijers, Ralph A. M. J.; Fishman, Gerald

    1999-01-01

    In this letter, we present for the first time evidence in the BATSE data for a prompt high-energy (25-300 keV) afterglow component from a Gamma-Ray Burst (GRB), GRB980923. The event ranks third highest in fluence (>25 keV) in the BATSE catalog and consists of a period of rapid variability lasting about 40 s followed by a smooth power law emission tail lasting about 400 s beyond the trigger time. An abrupt change in spectral shape is found when the tail becomes noticeable. Our analysis reveals that the spectral evolution in the tail of the burst mimics that of a cooling synchrotron spectrum, similar to the spectral evolution of the low-energy afterglows for GRBS. This evidence for a separate emission component is consistent with the internal-external shock scenario in the relativistic fireball picture. In particular, it illustrates that the external shocks can be generated during the primary gamma-ray emission phase, as in the case of GRB990123.

  9. Gamma-Ray Bursts: Afterglow and Prompt Emission Models

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    2008-10-01

    Swift observations have revealed interesting but puzzling data that demand a rethink of the origins of gamma-ray bursts (GRBs) and their afterglows. The chromatic breaks in X-ray/optical afterglow lightcurves stimulated several innovative suggestions, most invoking a non-forward-shock origin of the X-ray afterglows. The status of both the observational facts and the theoretical models is critically reviewed. Besides the late ``internal'' emission from a long-live central engine, most observed X-ray afterglows likely still include the contribution of the traditional forward shock component. The physical nature (e.g. energy dissipation mechanism, emission site, and radiation mechanism) of the GRB prompt emission is currently not identified. The motivations and issues of three proposed prompt emission sites are reviewed. Several independent methods, invoking prompt gamma-ray, X-ray, optical and GeV emission information, respectively, have been applied to constrain the unknown emission site. Tentative evidence suggests a large prompt emission radius. Finally, the implications of the broad band high quality data of the ``naked eye'' GRB 080319B for our understanding of the afterglow and prompt emission mechanisms are discussed.

  10. Shocked by the Very Bright Radio Flare and Afterglow of GRB 130427A

    NASA Astrophysics Data System (ADS)

    van der Horst, Alexander J.

    2014-01-01

    Gamma-ray burst (GRB) 130427A was extremely bright across the electromagnetic spectrum, with emission spanning 16 orders of magnitude in observing frequency, from almost 100 GeV gamma-rays down to the GHz radio regime. While the intrinsic luminosity of this GRB was not extreme compared to other GRBs, it displayed the largest measured fluence of the last three decades due to its proximity with a redshift of 0.34. One of the most notable characteristics of this GRB was its bright radio emission, in particular the radio flare which has been observed only a few times in other GRBs and is usually attributed to the reverse shock moving back into the GRB jet. Here we present radio observations with unprecedented temporal coverage at three observing frequencies obtained with the Westerbork Synthesis Radio Telescope (WSRT) and the Arcminute Microkelvin Imager (AMI). AMI had the earliest radio detection at 8 hours after the initial flash of gamma-rays, catching the radio flare on the rise. The 12-hour WSRT observations in the first few days enabled a detailed study of the short time-scale behavior at radio wavelengths. Besides our observations of the radio flare and afterglow up to three months after the gamma-ray trigger, we present our results for modeling the radio light curves together with the broadband data set in various other wavelength regimes, enabling us to determine physical parameters of both the reverse and forward shock of this enigmatic GRB.

  11. 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.

  12. Erratum: The Late Afterglow and Host Galaxy of GRB 990712

    NASA Astrophysics Data System (ADS)

    Hjorth, J.; Holland, S.; Courbin, F.; Dar, A.; Olsen, L. F.; Scodeggio, M.

    2000-08-01

    In the Letter ``The Late Afterglow and Host Galaxy of GRB 990712'' by J. Hjorth, S. Holland, F. Courbin, A. Dar, L. F. Olsen, & M. Scodeggio (ApJ, 534, L147 [2000]), there was an error in the flux calibration of the spectrum. The y-axis scale of Figure 2 and the fluxes in the last column of Table 1 should be multiplied by a factor of 3.47 to read 2.25, 0.86, 1.61, and 3.79×10-16 ergs s-1 cm-2. The error affects the luminosities and star formation rates (SFRs) presented in the third and fourth paragraphs of § 5 as follows. In the third paragraph, the total SFR based on the continuum flux should be 0.91-1.41 Msolar yr-1 instead of 0.29-0.45 the [O II] luminosity should be L3727=1.5×1041 ergs s-1 instead of 6.3×1040 and the implied [O II] SFR should be 2.12+/-0.60 Msolar yr-1 instead of 0.88+/-0.25. Consequently, the last two sentences of this paragraph are revised to read ``The derived SFR (from the [O II] flux) is about half of the SFR found by Bloom et al. (1999b) for the host of GRB 990123 and 2-3 times that of the host of GRB 970508 (Bloom et al. 1998). The specific SFR per unit luminosity of the GRB 990712 host galaxy is comparable to that of the host galaxies of GRB 990123 and GRB 970508.'' In the fourth paragraph, the total V-band flux in the feature should be 0.405+/-0.004 μJy instead of 0.323+/-0.003 the power-law spectral index should be β=-2.57 instead of -2.93 and the SFR in the feature should be 0.11-0.17 Msolar instead of 0.03-0.05. The main results and conclusions of the original Letter are unaffected by the error. The authors thank P. M. Vreeswijk for bringing this error to their attention.

  13. GRB Discoveries with Swift

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2008-01-01

    This brief presentation presents Swift Observatory recordings of gamma ray burst (GRB) activity. Long and short GRBs and afterglows are highlighted. Recordings of GRB emission, afterglow, optical/IR brightness, and flux density are presented. The time structure and current status of short GRB structures is also included.

  14. The puzzling afterglow of GRB 050721: a rebrightening seen in the optical but not in the X-ray

    SciTech Connect

    Antonelli, L. A.; Romano, P.; Testa, V.; D'Elia, V.; Guetta, D.; Torii, K.; Malesani, D.

    2007-08-21

    We present here the analysis of the early and late multiwavelength afterglow emission, as observed by Swift a small robotic telescope, and the VLT. We compare early observations with late afterglow observations obtained with Swift and the VLT and we observe an intense rebrightening in the optical band at about one day after the burst which is not present in the X-ray band. The lack of detection in X-ray of such a strong rebrightening at lower energies may be described with a variable external density profile. In such a scenario, the combined X-ray and optical observations allow us to derive that the matter density located at {approx} 1017 cm from the burst is about a factor of 10 higher than in the inner region. This is the first time in which a rebrightening has been observed in the optical afterglow of a GRB that is clearly absent in the X-ray afterglow.

  15. An inverse Compton origin for the 55 GeV photon in the late afterglow of GRB 130907A

    SciTech Connect

    Tang, Qing-Wen; Wang, Xiang-Yu; Tam, Pak-Hin Thomas E-mail: phtam@phys.nthu.edu.tw

    2014-06-20

    The extended high-energy gamma-ray (>100 MeV) emission which occurs well after the prompt gamma-ray bursts (GRBs) is usually explained as the afterglow synchrotron radiation. Here we report the analysis of Fermi Large Area Telescope observations of GRB 130907A. A 55 GeV photon compatible with the position of the burst was found about 5 hr after the prompt phase. The probability that this photon is associated with GRB 130907A is higher than 99.96%. The energy of this photon exceeds the maximum synchrotron photon energy at this time and its occurrence thus challenges the synchrotron mechanism as the origin for the extended high-energy >10 GeV emission. Modeling of the broadband spectral energy distribution suggests that such high energy photons can be produced by the synchrotron self-Compton emission of the afterglow.

  16. Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data

    NASA Technical Reports Server (NTRS)

    Nousek, J. A.; Kouveliotou, C.; Grupe, D.; Page, K.; Granot, J.; Ramirez-Ruiz, E.; Patel, S. K.; Burrows, D. N.; Mangano, V.; Barthelmy, S.

    2005-01-01

    We present new observations of the early X-ray afterglows of the first 27 gamma-ray bursts (GRBs) detected with the Swift X-ray Telescope (XRT). The early X-ray afterglows show a canonical behavior, where the light curve broadly consists of three distinct power law segments. These power law segments are separated by two corresponding break times. On top of this canonical behavior of the early X-ray light curve, many events have superimposed X-ray flares, which are most likely caused by internal shocks due to long lasting sporadx activity of the central engine, up to several hours after the GRB. We find that the initial steep decay is consistent with it being the tail of the prompt emission: from photons that are radiated at large angles relative to our line of sight. The first break in the light curve takes place when the forward shock emission becomes dominant, with the intermediate shallow flux decay likely caused by the continuous energy injection into the external shock. When this energy injection stops, a second break is then observed in the light curve. This energy injection increases the energy of the afterglow shock by at least a factor of f greater than or approx. equal to 4, and augments the already severe requirements for the efficiency of the prompt gamma-ray emission.

  17. Swift Late GRB Emission and GLAST

    SciTech Connect

    Butler, Nathaniel

    2007-07-12

    Recent observations of early X-ray afterglows of GRBs by the Swift satellite - prior to t {approx} 103s but well after the end of the burst - show most GRBs to be followed by highly time and energy variable emission. This was unexpected prior to Swift and physical mechanisms remain largely mysterious. The spectra exhibit a strong hard-to-soft evolution which tracks the flux, consistent with a well-established hardness intensity correlation for the prompt Gamma-ray emission. The light curves show dramatic flares or rapid logarithmic time decays. In the simplest interpretation, this emission is GRB-like and indicates a long lived energy source with the possibility of interacting shells of widely varying bulk Lorentz factor. We review the phenomenology in order to ascertain how GLAST observations of this early emission, either detected directly or through the detection of inverse-Compton emission, can help to rule on possible models.

  18. 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.; Rau, A.; Stecklum, B.; Castro-Tirado, A. J.; Fynbok J. P. U.; Hjorth, J.; Jakobsson, P.; Kouveliotou, C.; Masetti, N.; Pian, E.; Tanvir, N. R.; Wijers, R. A. M. J.

    2006-01-01

    We report early follow-up observations of the error box of the short burst 050813 using the telescopes at Calar Alto and at Observatorio Sierra Nevada (OSN), followed by deep VLT/FORS2 I-band observations obtained under very good seeing conditions 5.7 and 11.7 days after the event. No evidence for a GRB afterglow was found in our Calar Alto and OSN data, no rising supernova component was detected in our FORS2 images. A potential host galaxy can be identified in our FORS2 images, even though we cannot state with certainty its association with GRB 050813. IN any case, the optical afterglow of GRB 050813 was very faint, well in agreement with what is known so far about the optical properties of afterglows of short bursts. We conclude that all optical data are not in conflict with the interpretation that GRB 050813 was a short burst.

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

    SciTech Connect

    Zafar, Tayyaba; Watson, Darach; Eliasdottir, Ardis; Fynbo, Johan P. U.; Kruehler, Thomas; Leloudas, Giorgos; Schady, Patricia; Greiner, Jochen; Jakobsson, Pall; Thoene, Christina C.; Perley, Daniel A.; Morgan, Adam N.; Bloom, Joshua E-mail: darach@dark-cosmology.dk

    2012-07-01

    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 with 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

  20. The X-Ray Afterglow of Dark GRB 970815: A Common Origin for Gamma-Ray Bursts and X-Ray Flashes?

    NASA Astrophysics Data System (ADS)

    Mirabal, N.; Halpern, J. P.; Gotthelf, E. V.; Mukherjee, R.

    2005-02-01

    GRB 970815 is a well-localized gamma-ray burst (GRB) detected by the All-Sky Monitor (ASM) on the Rossi X-Ray Timing Explorer (RXTE) for which no afterglow was identified despite follow-up ASCA and ROSAT pointings and optical imaging to limiting magnitude R>23. Although an X-ray source, AX/RX J1606.8+8130, was detected just outside the ASM error box, it was never associated with the GRB because it was not clearly fading and because no optical afterglow was ever found. We recently obtained an upper limit for this source with Chandra that is at least a factor of 100 fainter than the ASCA detection. We also made deep optical observations of the AX/RX J1606.8+8130 position, which is blank to limits V>25.2 and I>24.0. In view of these extreme limits, we conclude that AX/RX J1606.8+8130 is indeed the afterglow of GRB 970815, which corresponds to an optically ``dark'' GRB. AX/RX J1606.8+8130 can therefore be ruled out as the counterpart of the persistent EGRET source 3EG J1621+8203. The early light curves from BATSE and the RXTE ASM show spectral softening between multiple peaks of prompt emission. We propose that GRB 970815 might be a case in which the properties of an X-ray flash and a ``normal'' GRB coincide in a single event.

  1. Study of GRB Light-curve Decay Indices in the Afterglow Phase

    NASA Astrophysics Data System (ADS)

    Del Vecchio, Roberta; Giovanna Dainotti, Maria; Ostrowski, Michał

    2016-09-01

    In this work, we study the distribution of temporal power-law decay indices, α, in the gamma-ray burst (GRB) afterglow phase, fitted for 176 GRBs (139 long GRBs, 12 short GRBs with extended emission, and 25 X-ray flashes) with known redshifts. These indices are compared with the temporal decay index, α W , derived with the light-curve fitting using the Willingale et al. model. This model fitting yields similar distributions of α W to the fitted α, but for individual bursts a difference can be significant. Analysis of (α, L a ) distribution, where L a is the characteristic luminosity at the end of the plateau, reveals only a weak correlation of these quantities. However, we discovered a significant regular trend when studying GRB α values along the Dainotti et al. correlation between L a and the end time of the plateau emission in the rest frame, {T}a* , hereafter LT correlation. We note a systematic variation of the α parameter distribution with luminosity for any selected {T}a* . We analyze this systematics with respect to the fitted LT correlation line, expecting that the presented trend may allow us to constrain the GRB physical models. We also attempted to use the derived correlation of α ({T}a) versus {L}a({T}a) to diminish the luminosity scatter related to the variations of α along the LT distribution, a step forward in the effort of standardizing GRBs. A proposed toy model accounting for this systematics applied to the analyzed GRB distribution results in a slight increase of the LT correlation coefficient.

  2. Alternate Search for Jet Breaks in Long GRB X-ray Afterglows

    NASA Astrophysics Data System (ADS)

    Garmire, Gordon

    2014-09-01

    In the standard fireball models of GRB afterglows, the jet opening angle can be determined from the achromatic jet break by measuring the time at which this break in the light curves occurs. This measure allows us to estimate the energy budget of the GRB explosion. Swift XRT observations have shown that jet breaks are not observed in the first several days or weeks of a typical X-ray afterglow. We have already exploited Chandra's better sensitivity to observe late XRT afterglows and put more stringent constraints on jet break times, and started a program to interpret results with more realistic jet models. We propose to observe 3 more exceptionally bright X-ray afterglows of GRBs from the past year that in absence of jet break would still be detectable in this cycle.

  3. GEMINI SPECTROSCOPY OF THE SHORT-HARD GAMMA-RAY BURST GRB 130603B AFTERGLOW AND HOST GALAXY

    SciTech Connect

    Cucchiara, A.; Prochaska, J. X.; Werk, J.; Cenko, S. B.; Cardwell, A.; Turner, J.; Bloom, J. S.; Cobb, B. E.

    2013-11-10

    We present early optical photometry and spectroscopy of the afterglow and host galaxy of the bright short-duration gamma-ray burst GRB 130603B discovered by the Swift satellite. Using our Target of Opportunity program on the Gemini South telescope, our prompt optical spectra reveal a strong trace from the afterglow superimposed on continuum and emission lines from the z = 0.3568 ± 0.0005 host galaxy. The combination of a relatively bright optical afterglow (r' = 21.52 at Δt = 8.4 hr), together with an observed offset of 0.''9 from the host nucleus (4.8 kpc projected distance at z = 0.3568), allow us to extract a relatively clean spectrum dominated by afterglow light. Furthermore, the spatially resolved spectrum allows us to constrain the properties of the explosion site directly, and compare these with the host galaxy nucleus, as well as other short-duration GRB host galaxies. We find that while the host is a relatively luminous (L∼0.8 L{sup *}{sub B}), star-forming (SFR = 1.84 M{sub ☉} yr{sup –1}) galaxy with almost solar metallicity, the spectrum of the afterglow exhibits weak Ca II absorption features but negligible emission features. The explosion site therefore lacks evidence of recent star formation, consistent with the relatively long delay time distribution expected in a compact binary merger scenario. The star formation rate (SFR; both in an absolute sense and normalized to the luminosity) and metallicity of the host are both consistent with the known sample of short-duration GRB hosts and with recent results which suggest GRB 130603B emission to be the product of the decay of radioactive species produced during the merging process of a neutron-star-neutron-star binary ({sup k}ilonova{sup )}. Ultimately, the discovery of more events similar to GRB 130603B and their rapid follow-up from 8 m class telescopes will open new opportunities for our understanding of the final stages of compact-objects binary systems and provide crucial information

  4. The First Swift Ultraviolet/Optical Telescope GRB Afterglow Catalog

    NASA Astrophysics Data System (ADS)

    Roming, P. W. A.; Koch, T. S.; Oates, S. R.; Porterfield, B. L.; Vanden Berk, D. E.; Boyd, P. T.; Holland, S. T.; Hoversten, E. A.; Immler, S.; Marshall, F. E.; Page, M. J.; Racusin, J. L.; Schneider, D. P.; Breeveld, A. A.; Brown, P. J.; Chester, M. M.; Cucchiara, A.; DePasquale, M.; Gronwall, C.; Hunsberger, S. D.; Kuin, N. P. M.; Landsman, W. B.; Schady, P.; Still, M.

    2009-01-01

    We present the first Swift Ultraviolet/Optical Telescope (UVOT) gamma-ray burst (GRB) afterglow catalog. The catalog contains data from over 64,000 independent UVOT image observations of 229 GRBs first detected by Swift, the High Energy Transient Explorer 2 (HETE2), the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), and the Interplanetary Network (IPN). The catalog covers GRBs occurring during the period from 2005 January 17 to 2007 June 16 and includes ~86% of the bursts detected by the Swift Burst Alert Telescope (BAT). The catalog provides detailed burst positional, temporal, and photometric information extracted from each of the UVOT images. Positions for bursts detected at the 3σ level are provided with a nominal accuracy, relative to the USNO-B1 catalog, of ~0farcs25. Photometry for each burst is given in three UV bands, three optical bands, and a "white" or open filter. Upper limits for magnitudes are reported for sources detected below 3σ. General properties of the burst sample and light curves, including the filter-dependent temporal slopes, are also provided. The majority of the UVOT light curves, for bursts detected at the 3σ level, can be fit by a single power-law, with a median temporal slope (α) of 0.96, beginning several hundred seconds after the burst trigger and ending at ~1 × 105 s. The median UVOT v-band (~5500 Å) magnitude at 2000 s for a sample of "well"-detected bursts is 18.02. The UVOT flux interpolated to 2000 s after the burst, shows relatively strong correlations with both the prompt Swift BAT fluence, and the Swift X-ray flux at 11 hr after the trigger.

  5. Evidence for a Canonical GRB Afterglow Light Curve in the Swift/XRT Data

    SciTech Connect

    Nousek, J.A.; Kouveliotou, C.; Grupe, D.; Page, K.; Granot, J.; Ramirez-Ruiz, E.; Patel, S.K.; Burrows, D.N.; Mangano, V.; Barthelmy, S.; Beardmore, A.P.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G.; Falcone, A.D.; Gehrels, N.; Giommi, P.; Goad, M.; Godet, O.; Hurkett, C.; /Penn State U., Astron. Astrophys. /NASA, Marshall /Leicester U. /KIPAC, Menlo Park /Princeton, Inst. Advanced Study /NASA, Marshall /IASF, Palermo /Brera Observ. /Frascati /Milan Bicocca U. /NASA, Goddard

    2005-08-17

    We present new observations of the early X-ray afterglows of the first 27 gamma-ray bursts (GRBs) detected with the Swift X-ray Telescope (XRT). The early X-ray afterglows show a canonical behavior, where the light curve broadly consists of three distinct power law segments: (1) an initial very steep decay ({infinity} t{sup -a} with 3 {approx}< a{sub 1} {approx}< 5) , followed by (2) a very shallow decay (0.2 {approx}< a{sub 2} {approx}< 0.8), and finally (3) a somewhat steeper decay (1 {approx}< a{sub 3} {approx}< 1.5). These power law segments are separated by two corresponding break times, 300 s {approx}< t{sub break,1} {approx}< 500 s and 10{sup 3} s {approx}< t{sub break,2} {approx}< 10{sup 4} s. On top of this canonical behavior of the early X-ray light curve, many events have superimposed X-ray flares, which are most likely caused by internal shocks due to long lasting sporadic activity of the central engine, up to several hours after the GRB. We find that the initial steep decay is consistent with it being the tail of the prompt emission, from photons that are radiated at large angles relative to our line of sight. The first break in the light curve (t{sub break,1}) takes place when the forward shock emission becomes dominant, with the intermediate shallow flux decay (a{sub 2}) likely caused by the continuous energy injection into the external shock. When this energy injection stops, a second break is then observed in the light curve (t{sub break,2}). This energy injection increases the energy of the afterglow shock by at least a factor of f {approx}> 4, and augments the already severe requirements for the efficiency of the prompt gamma-ray emission.

  6. 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

  7. THE AFTERGLOW AND ULIRG HOST GALAXY OF THE DARK SHORT GRB 120804A

    SciTech Connect

    Berger, E.; Zauderer, B. A.; Margutti, R.; Laskar, T.; Fong, W.; Chornock, R.; Dupuy, T. J.; Levan, A.; Tunnicliffe, R. L.; Mangano, V.; Fox, D. B.; Tanvir, N. R.; Menten, K. M.; Hjorth, J.; Roth, K.

    2013-03-10

    We present the optical discovery and subarcsecond optical and X-ray localization of the afterglow of the short GRB 120804A, as well as optical, near-IR, and radio detections of its host galaxy. X-ray observations with Swift/XRT, Chandra, and XMM-Newton extending to {delta}t Almost-Equal-To 19 days reveal a single power-law decline. The optical afterglow is faint, and comparison to the X-ray flux indicates that GRB 120804A is ''dark'', with a rest-frame extinction of A {sup host}{sub V} Almost-Equal-To 2.5 mag (at z = 1.3). The intrinsic neutral hydrogen column density inferred from the X-ray spectrum, N{sub H,{sub int}}(z = 1.3) Almost-Equal-To 2 Multiplication-Sign 10{sup 22} cm{sup -2}, is commensurate with the large extinction. The host galaxy exhibits red optical/near-IR colors. Equally important, JVLA observations at Almost-Equal-To 0.9-11 days reveal a constant flux density of F{sub {nu}}(5.8 GHz) = 35 {+-} 4 {mu}Jy and an optically thin spectrum, unprecedented for GRB afterglows, but suggestive instead of emission from the host galaxy. The optical/near-IR and radio fluxes are well fit with the scaled spectral energy distribution of the local ultraluminous infrared galaxy (ULIRG) Arp 220 at z Almost-Equal-To 1.3, with a resulting star formation rate of x Almost-Equal-To 300 M{sub Sun} yr{sup -1}. The inferred extinction and small projected offset (2.2 {+-} 1.2 kpc) are also consistent with the ULIRG scenario, as is the presence of a companion galaxy at the same redshift and with a separation of about 11 kpc. The limits on radio afterglow emission, in conjunction with the observed X-ray and optical emission, require a circumburst density of n {approx} 10{sup -3} cm{sup -3}, an isotropic-equivalent energy scale of E{sub {gamma},{sub iso}} Almost-Equal-To E{sub K,{sub iso}} Almost-Equal-To 7 Multiplication-Sign 10{sup 51} erg, and a jet opening angle of {theta}{sub j} {approx}> 11 Degree-Sign . The expected fraction of luminous infrared galaxies in the short GRB

  8. Energy input and response from prompt and early optical afterglow emission in gamma-ray bursts.

    PubMed

    Vestrand, W T; Wren, J A; Wozniak, P R; Aptekar, R; Golentskii, S; Pal'shin, V; Sakamoto, T; White, R R; Evans, S; Casperson, D; Fenimore, E

    2006-07-13

    The taxonomy of optical emission detected during the critical first few minutes after the onset of a gamma-ray burst (GRB) defines two broad classes: prompt optical emission correlated with prompt gamma-ray emission, and early optical afterglow emission uncorrelated with the gamma-ray emission. The standard theoretical interpretation attributes prompt emission to internal shocks in the ultra-relativistic outflow generated by the internal engine; early afterglow emission is attributed to shocks generated by interaction with the surrounding medium. Here we report on observations of a bright GRB that, for the first time, clearly show the temporal relationship and relative strength of the two optical components. The observations indicate that early afterglow emission can be understood as reverberation of the energy input measured by prompt emission. Measurements of the early afterglow reverberations therefore probe the structure of the environment around the burst, whereas the subsequent response to late-time impulsive energy releases reveals how earlier flaring episodes have altered the jet and environment parameters. Many GRBs are generated by the death of massive stars that were born and died before the Universe was ten per cent of its current age, so GRB afterglow reverberations provide clues about the environments around some of the first stars. PMID:16838015

  9. The afterglow and elliptical host galaxy of the short gamma-ray burst GRB 050724.

    PubMed

    Berger, E; Price, P A; Cenko, S B; Gal-Yam, A; Soderberg, A M; Kasliwal, M; Leonard, D C; Cameron, P B; Frail, D A; Kulkarni, S R; Murphy, D C; Krzeminski, W; Piran, T; Lee, B L; Roth, K C; Moon, D-S; Fox, D B; Harrison, F A; Persson, S E; Schmidt, B P; Penprase, B E; Rich, J; Peterson, B A; Cowie, L L

    2005-12-15

    Despite a rich phenomenology, gamma-ray bursts (GRBs) are divided into two classes based on their duration and spectral hardness--the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing their origin to star-forming galaxies, and hence the death of massive stars, and indicating an energy release of about 10(51) erg. While theoretical arguments suggest that short GRBs are produced in the coalescence of binary compact objects (neutron stars or black holes), the progenitors, energetics and environments of these events remain elusive despite recent localizations. Here we report the discovery of the first radio afterglow from the short burst GRB 050724, which unambiguously associates it with an elliptical galaxy at a redshift z = 0.257. We show that the burst is powered by the same relativistic fireball mechanism as long GRBs, with the ejecta possibly collimated in jets, but that the total energy release is 10-1,000 times smaller. More importantly, the nature of the host galaxy demonstrates that short GRBs arise from an old (> 1 Gyr) stellar population, strengthening earlier suggestions and providing support for coalescing compact object binaries as the progenitors. PMID:16355217

  10. A possible macronova in the late afterglow of the long-short burst GRB 060614.

    PubMed

    Yang, Bin; Jin, Zhi-Ping; Li, Xiang; Covino, Stefano; Zheng, Xian-Zhong; Hotokezaka, Kenta; Fan, Yi-Zhong; Piran, Tsvi; Wei, Da-Ming

    2015-01-01

    Long-duration (>2 s) γ-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczyński macronova--the radioactive decay of debris following a compact binary merger. If this interpretation is correct, GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favours a black hole-neutron star merger but a double neutron star merger cannot be ruled out. PMID:26065563

  11. A possible macronova in the late afterglow of the long–short burst GRB 060614

    PubMed Central

    Yang, Bin; Jin, Zhi-Ping; Li, Xiang; Covino, Stefano; Zheng, Xian-Zhong; Hotokezaka, Kenta; Fan, Yi-Zhong; Piran, Tsvi; Wei, Da-Ming

    2015-01-01

    Long-duration (>2 s) γ-ray bursts that are believed to originate from the death of massive stars are expected to be accompanied by supernovae. GRB 060614, that lasted 102 s, lacks a supernova-like emission down to very stringent limits and its physical origin is still debated. Here we report the discovery of near-infrared bump that is significantly above the regular decaying afterglow. This red bump is inconsistent with even the weakest known supernova. However, it can arise from a Li-Paczyński macronova—the radioactive decay of debris following a compact binary merger. If this interpretation is correct, GRB 060614 arose from a compact binary merger rather than from the death of a massive star and it was a site of a significant production of heavy r-process elements. The significant ejected mass favours a black hole–neutron star merger but a double neutron star merger cannot be ruled out. PMID:26065563

  12. Measuring the beaming angle of GRB 030329 by fitting the rebrightenings in its multiband afterglow

    NASA Astrophysics Data System (ADS)

    Deng, Wei; Huang, Yong-Feng; Kong, Si-Wei

    2010-11-01

    Multiple rebrightenings have been observed in the multiband afterglow of GRB 030329. In particular, a marked and quick rebrightening occurred at about t ~ 1.2 × 105 s. Energy injection from late and slow shells seems to be the best interpretation for these rebrightenings. Usually it is assumed that the energy is injected into the whole external shock. However, in the case of GRB 030329, the rebrightenings are so quick that the usual consideration fails to give a satisfactory fit to the observed light curves. Actually, since these late/slow shells freely coast in the wake of the external shock, they should be cold and may not expand laterally. The energy injection then should only occur at the central region of the external shock. Considering this effect, we numerically re-fit the quick rebrightenings observed in GRB 030329. By doing this, we were able to derive the beaming angle of the energy injection process. Our result, with a relative residual of only 5% - 10% during the major rebrightening, is better than any previous modeling. The derived energy injection angle is about 0.035. We assume that these late shells are ejected by the central engine via the same mechanism as those early shells that produce the prompt gamma-ray burst. The main difference is that their velocities are much slower, so that they catch up with the external shock relatively late and are manifested as the observed quick rebrightenings. If this were true, then the derived energy injection angle can give a good measure of the beaming angle of the prompt γ-ray emission. Our study may hopefully provide a novel method to measure the beaming angle of gamma-ray bursts.

  13. GRB 070125 and the environments of spectral-line poor afterglow absorbers

    NASA Astrophysics Data System (ADS)

    De Cia, A.; Starling, R. L. C.; Wiersema, K.; van der Horst, A. J.; Vreeswijk, P. M.; Björnsson, G.; de Ugarte Postigo, A.; Jakobsson, P.; Levan, A. J.; Rol, E.; Schulze, S.; Tanvir, N. R.

    2011-11-01

    GRB 070125 is among the most energetic bursts detected and the most extensively observed so far. Nevertheless, unresolved issues are still open in the literature on the physics of the afterglow and on the gamma-ray burst (GRB) environment. In particular, GRB 070125 was claimed to have exploded in a galactic halo environment, based on the uniqueness of the optical spectrum and the non-detection of an underlying host galaxy. In this work we collect all publicly available data and address these issues by modelling the near-infrared to X-ray spectral energy distribution (SED) and studying the high signal-to-noise ratio Very Large Telescope/FOcal Reducer/low dispersion Spectrograph afterglow spectrum in comparison with a larger sample of GRB absorbers. The SED reveals a synchrotron cooling break in the ultraviolet, low equivalent hydrogen column density and little reddening caused by a Large Magellanic Cloud type or Small Magellanic Cloud type extinction curve. From the weak Mg II absorption at z= 1.5477 in the spectrum, we derived log N(Mg II) = 12.96+0.13- 0.18 and upper limits on the ionic column density of several metals. These suggest that the GRB absorber is most likely a Lyman limit system with a 0.03 < Z < 1.3 Z⊙ metallicity. The comparison with other GRB absorbers places GRB 070125 at the low end of the absorption-line equivalent width distribution, confirming that weak spectral features and spectral-line poor absorbers are not so uncommon in afterglow spectra. Moreover, we show that the effect of photoionization on the gas surrounding the GRB, combined with a low N(H I) along a short segment of the line of sight within the host galaxy, can explain the lack of spectral features in GRB 070125. Finally, the non-detection of an underlying galaxy is consistent with a faint GRB host galaxy, well within the GRB host brightness distribution. Thus, the possibility that GRB 070125 is simply located in the outskirts of a gas-rich, massive star-forming region inside its

  14. 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.

  15. GRB Orphan Afterglows in Present and Future Radio Transient Surveys

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Burlon, D.; Ghisellini, G.; Salvaterra, R.; Bernardini, M. G.; Campana, S.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Melandri, A.; Murphy, T.; Nava, L.; Vergani, S. D.; Tagliaferri, G.

    2014-05-01

    Orphan Afterglows (OA) are slow transients produced by Gamma Ray Bursts seen off-axis that become visible on timescales of days/years at optical/NIR and radio frequencies, when the prompt emission at high energies (X and γ rays) has already ceased. Given the typically estimated jet opening angle of GRBs θjet ~ 3°, for each burst pointing to the Earth there should be a factor ~ 700 more GRBs pointing in other directions. Despite this, no secure OAs have been detected so far. Through a population synthesis code we study the emission properties of the population of OA at radio frequencies. OAs reach their emission peak on year-timescales and they last for a comparable amount of time. The typical peak fluxes (which depend on the observing frequency) are of few μJy in the radio band with only a few OA reaching the mJy level. These values are consistent with the upper limits on the radio flux of SN Ib/c observed at late times. We find that the OA radio number count distribution has a typical slope - 1.7 at high fluxes and a flatter ( - 0.4) slope at low fluxes with a break at a frequency-dependent flux. Our predictions of the OA rates are consistent with the (upper) limits of recent radio surveys and archive searches for radio transients. Future radio surveys like VAST/ASKAP at 1.4 GHz should detect ~ 3 × 10- 3 OA deg- 2 yr- 1, MeerKAT and EVLA at 8.4 GHz should see ~ 3 × 10- 1 OA deg- 2 yr- 1. The SKA, reaching the μJy flux limit, could see up to ~ 0.2 - 1.5 OA deg- 2 yr- 1. These rates also depend on the duration of the OA above a certain flux limit and we discuss this effect with respect to the survey cadence.

  16. 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.

  17. The Late-time Afterglow of the Extremely Energetic Short Burst GRB 090510 Revisited

    NASA Technical Reports Server (NTRS)

    Guelbenzu, A. Nicuesa; Klose, S.; Kruehler, T.; Greiner, J.; Rossi, A.; Kann, D. A.; Olivares, F.; Rau, A.; Afonso, P. M. J.; Elliott, J.; Filgas, R.; Yoldas, A. Kuepcue; McBreen, S.; Nardini, M.; Schady, P.; Schmidl, S.; Sudilovsky, V.; Updike, A. C.; Yoldas, A.

    2012-01-01

    Context. The Swift discovery of the short burst GRB 090510 has raised considerable attention mainly because of two reasons: first, it had a bright optical afterglow, and second it is among the most energetic events detected so far within the entire GRB population (long plus short). The afterglow of GRB 090510 was observed with Swift/UVOT and Swift/XRT and evidence of a jet break around 1.5 ks after the burst has been reported in the literature, implying that after this break the optical and X-ray light curve should fade with the same decay slope. Aims. As noted by several authors, the post-break decay slope seen in the UVOT data is much shallower than the steep decay in the X-ray band, pointing to a (theoretically hard to understand) excess of optical flux at late times. We assess here the validity of this peculiar behavior. Methods. We reduced and analyzed new afterglow light-curve data obtained with the multichannel imager GROND. These additional g'r'i'z' data were then combined with the UVOT and XRT data to study the behavior of the afterglow at late times more stringently. Results. Based on the densely sampled data set obtained with GROND, we find that the optical afterglow of GRB 090510 did indeed enter a steep decay phase starting around 22 ks after the burst. During this time the GROND optical light curve is achromatic, and its slope is identical to the slope of the X-ray data. In combination with the UVOT data this implies that a second break must have occurred in the optical light curve around 22 ks post burst, which, however, has no obvious counterpart in the X-ray band, contradicting the interpretation that this could be another jet break. Conclusions. The GROND data provide the missing piece of evidence that the optical afterglow of GRB 090510 did follow a post-jet break evolution at late times. The break seen in the optical light curve around 22 ks in combination with its missing counterpart in the X-ray band could be due to the passage of the

  18. The X-shooter sample of GRB afterglow spectra: Properties of the absorption features

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, Antonio

    2015-08-01

    Since its commissioning at ESO's Very Large Telescope in 2009, the X-shooter spectrograph has become the reference instrument in gamma-ray burst (GRB) afterglow spectroscopy. During this time our collaboration has collected more than 70 spectra of GRB afterglows, with redshifts ranging from 0.06 to 6.3. Thanks to their extreme luminosity and simple intrinsic shape, GRB spectra are optimal tools for the study of galactic environments at basically any redshift. Being produced by the death of short-lived massive stars, they are also tracers of star formation.I will present the sample of absorption spectral features identified in X-shooter's GRB spectra describing observation and analysis techniques. The different features are compared with the characteristics of the explosion (duration, spectral shape, energetics, etc.) and with the properties of the host galaxy (mass, age, etc.) to improve our understanding of the nature of the explosions and how they interact with their environments. Using the large redshift range of the spectra collection we perform studies of the evolution of GRB environments across the history of the Universe and their relation with the evolution of star formation.

  19. Linear and circular polarization in ultra-relativistic synchrotron sources - implications to GRB afterglows

    NASA Astrophysics Data System (ADS)

    Nava, Lara; Nakar, Ehud; Piran, Tsvi

    2016-01-01

    Polarization measurements from relativistic outflows are a valuable tool to probe the geometry of the emission region and the microphysics of the particle distribution. Indeed, the polarization level depends on (i) the local magnetic field orientation, (ii) the geometry of the emitting region with respect to the line of sight and (iii) the electron pitch angle distribution. Here we consider optically thin synchrotron emission and we extend the theory of circular polarization from a point source to an extended radially expanding relativistic jet. We present numerical estimates for both linear and circular polarization in such systems. We consider different configurations of the magnetic field, spherical and jetted outflows, isotropic and anisotropic pitch angle distributions, and outline the difficulty in obtaining the reported high level of circular polarization observed in the afterglow of Gamma Ray Burst (GRB) 121024A. We conclude that the origin of the observed polarization cannot be intrinsic to an optically thin synchrotron process, even when the electron pitch angle distribution is extremely anisotropic.

  20. Spectral softening in the X-RAY afterglow of GRB 130925A as predicted by the dust scattering model

    SciTech Connect

    Zhao, Yi-Nan; Shao, Lang

    2014-07-01

    Gamma-ray bursts (GRBs) usually occur in a dense star-forming region with a massive circumburst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences and sometimes can dominate the X-ray afterglow. In most of the previous studies, only the Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius of a ≤ 0.1 μm) in the diffuse interstellar medium. When the size of the grains may significantly increase, as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understand the puzzling X-ray afterglow of recently observed GRB 130925A that showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could well reproduce both the temporal and spectral profile simultaneously. Given the plateau present in the early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.

  1. Spectral Softening in the X-Ray Afterglow of GRB 130925A as Predicted by the Dust Scattering Model

    NASA Astrophysics Data System (ADS)

    Zhao, Yi-Nan; Shao, Lang

    2014-07-01

    Gamma-ray bursts (GRBs) usually occur in a dense star-forming region with a massive circumburst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences and sometimes can dominate the X-ray afterglow. In most of the previous studies, only the Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius of a <= 0.1 μm) in the diffuse interstellar medium. When the size of the grains may significantly increase, as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understand the puzzling X-ray afterglow of recently observed GRB 130925A that showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could well reproduce both the temporal and spectral profile simultaneously. Given the plateau present in the early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.

  2. VizieR Online Data Catalog: GRB 120815A afterglow spectra (Kruehler+, 2013)

    NASA Astrophysics Data System (ADS)

    Kruehler, T.; Ledoux, C.; Fynbo, J. P. U.; Vreeswijk, P. M.; Schmidl, S.; Malesani, D.; Christensen, L.; De Cia, A.; Hjorth, J.; Jakobsson, P.; Kann, D. A.; Kaper, L.; Vergani, S. D.; Afonso, P. M. J.; Covino, S.; de Ugarte Postigo, A.; D'Elia, V.; Filgas, R.; Goldoni, P.; Greiner, J.; Hartoog, O. E.; Milvang-Jensen, B.; Nardini, M.; Piranomonte, S.; Rossi, A.; Sanchez-Ramirez, R.; Schady, P.; Schulze, S.; Sudilovsky, V.; Tanvir, N. R.; Tagliaferri, G.; Watson, D. J.; Wiersema, K.; Wijers, R. A. M. J.; Xu, D.

    2013-07-01

    Flux-calibrated VLT/X-shooter medium resolution spectrum of the GRB 120815A afterglow. Spectroscopic observations of the GRB 120815A afterglow in the wavelength range between 3000 and 24800Å commenced on 2012-08-15 at 03:55 UT (6.06ks after the BAT trigger) with the cross-dispersed echelle spectrograph Xshooter mounted at ESO's Very Large Telescope (VLT) UT2. They consisted of four nodded exposures in the sequence ABBA with exposure times of 600s each, taken simultaneously in X-shooter's ultraviolet/blue (UVB - 3150-5900Å), visible (VIS - 5600-10080Å) and near-infrared (NIR - 10200-24080Å) arms with R~6000, 10400, 6200 for the UVB/VIS and NIR arm, respectively. (3 data files).

  3. VLBI AND ARCHIVAL VLA AND WSRT OBSERVATIONS OF THE GRB 030329 RADIO AFTERGLOW

    SciTech Connect

    Mesler, Robert A.; Pihlstroem, Ylva M.; Taylor, Greg B.; Granot, Johnathan

    2012-11-01

    We present VLBI and archival Karl G. Jansky Very Large Array (VLA) and Westerbork Synthesis Radio Telescope (WSRT) observations of the radio afterglow from the gamma-ray burst (GRB) of 2003 March 29 (GRB 030329) taken between 672 and 2032 days after the burst. The VLA and WSRT data suggest a simple power-law decay in the flux at 5 GHz, with no clear signature of any rebrightening from the counterjet. We report an unresolved source at day 2032 of size 1.18 {+-} 0.13 mas, which we use in conjunction with the expansion rate of the burst to argue for the presence of a uniform, interstellar-medium-like circumburst medium. A limit of <0.067 mas yr{sup -1} is placed on the proper motion, supporting the standard afterglow model for gamma-ray bursts.

  4. GRB 131231A: IMPLICATIONS OF THE GeV EMISSION

    SciTech Connect

    Liu, Bin; Chen, Wei; Liang, Yun-Feng; Zhou, Bei; He, Hao-Ning; Jin, Zhi-Ping; Fan, Yi-Zhong; Wei, Da-Ming; Tam, Pak-Hin Thomas; Shao, Lang E-mail: beizhou@pmo.ac.cn E-mail: dmwei@pmo.ac.cn

    2014-05-20

    GRB 131231A was detected by the Large Area Telescope on board the Fermi Space Gamma-ray Telescope. The high-energy gamma-ray (>100 MeV) afterglow emission spectrum is F {sub ν}∝ν{sup –0.54} {sup ±} {sup 0.15} in the first ∼1300 s after the trigger and the most energetic photon has an energy of ∼62 GeV, arriving at t ∼ 520 s. With reasonable parameters of the gamma-ray burst (GRB) outflow as well as the density of the circum-burst medium, the synchrotron radiation of electrons or protons accelerated at an external forward shock have difficulty accounting for the data. Rather, the synchrotron self-Compton radiation of the forward shock-accelerated electrons can account for both the spectrum and temporal behavior of the GeV afterglow emission. We also show that the prospect for detecting GRB 131231A-like GRBs with the Cherenkov Telescope Array is promising.

  5. iPTF14yb: The First GRB Discovered Outside the Gamma-Ray Bandpass and the Rate of Orphan Afterglows

    NASA Astrophysics Data System (ADS)

    Cenko, Stephen

    2015-04-01

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, the first unambiguous detection of an afterglow-like transient identified outside the γ-ray bandpass. Subsequent to our discovery announcement, the ``parent'' γ-ray burst GRB 140226A was identified by the InterPlanetary Network of high-energy detectors. We demonstrate an association between iPTF14yb and GRB 140226A based both on probabilistic arguments and by comparing iPTF14yb with the known population of long GRB afterglows and host galaxies. We furthermore estimate the rate of iPTF14yb-like transients based on iPTF observations, and demonstrate it is consistent with the rate of on-axis long GRBs. Finally, we briefly discuss the implications of the non-detection to date of bona fide ``orphan'' afterglows (i.e., those lacking entirely in high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.

  6. The origin of the plateau and late rebrightening in the afterglow of GRB 120326A

    SciTech Connect

    Hou, S. J.; Lu, J. F.; Geng, J. J.; Wang, K.; Huang, Y. F.; Dai, Z. G.; Wu, X. F.

    2014-04-20

    GRB 120326A is an unusual gamma-ray burst (GRB) that has a long plateau and a very late rebrightening in both X-ray and optical bands. The similar behavior of the optical and X-ray light curves suggests that they may share a common origin. The long plateau starts at several hundred seconds and ends at tens of thousands of seconds, and the peak time of the late rebrightening is about 30,000 s. We analyze the energy injection model by means of numerical and analytical solutions, considering both the wind environment and the interstellar medium environment for GRB afterglows. We particularly study the influence of the injection starting time, ending time, stellar wind density (or density of the circumburst environment), and injection luminosity on the shape of the afterglow light curves, respectively. In the wind model, we find that the light curve is largely affected by the parameters and that there is a 'bump' in the late stage. In the wind environment, we found that the longer the energy is injected, the more obvious the rebrightening will be. We also find that the peak time of the bump is determined by the stellar wind density. We use the late continuous injection model to interpret the unusual afterglow of GRB 120326A. The model fits the observational data well; however, we find that the timescale of the injection must be higher than 10,000 s, which implies that the timescale of the central engine activity must also be more than 10,000 s. This information can give useful constraints on the central engines of GRBs—we consider a newborn millisecond pulsar with a strong magnetic field to be the central engine. On the other hand, our results suggest that the circumburst environment of GRB 120326A is very likely a stellar wind.

  7. VLT/X-shooter spectroscopy of the GRB 120327A afterglow

    NASA Astrophysics Data System (ADS)

    D'Elia, V.; Fynbo, J. P. U.; Goldoni, P.; Covino, S.; de Ugarte Postigo, A.; Ledoux, C.; Calura, F.; Gorosabel, J.; Malesani, D.; Matteucci, F.; Sánchez-Ramírez, R.; Savaglio, S.; Castro-Tirado, A. J.; Hartoog, O. E.; Kaper, L.; Muñoz-Darias, T.; Pian, E.; Piranomonte, S.; Tagliaferri, G.; Tanvir, N.; Vergani, S. D.; Watson, D. J.; Xu, D.

    2014-04-01

    Aims: We present a study of the environment of the Swift long gamma-ray burst GRB 120327A at z ≈ 2.8 through optical spectroscopy of its afterglow. Methods: We analyzed medium-resolution, multi-epoch spectroscopic observations (R ~ 7000-12 000, corresponding to ~15-23 km s-1, S/N = 15-30 and wavelength range 3000-25 000 Å) of the optical afterglow of GRB 120327A, taken with X-shooter at the VLT 2.13 and 27.65 hr after the GRB trigger. Results: The first epoch spectrum shows that the ISM in the GRB host galaxy at z = 2.8145 is extremely rich in absorption features, with three components contributing to the line profiles. The hydrogen column density associated with GRB 120327A has log NH/cm-2 = 22.01 ± 0.09, and the metallicity of the host galaxy is in the range [X/H] = -1.3 to -1.1. In addition to the ground state lines, we detect absorption features associated with excited states of C ii, O i, Si ii, Fe ii, and Ni ii, which we used to derive information on the distance between the host absorbing gas and the site of the GRB explosion. The variability of the Fe iiλ2396 excited line between the two epochs proves that these features are excited by the GRB UV flux. Moreover, the distance of component I is found to be dI = 200+100-60 pc, while component II is located closer to the GRB, at dII = 100+40-30 pc. These values are among the lowest found in GRBs. Component III does not show excited transitions, so it should be located farther away from the GRB. The presence of H2 molecules is firmly established, with a molecular fraction f in the range f = 4 × 10-7-10-4. This particularly low value can be attributed to the small dust content. This represents the third positive detection of molecules in a GRB environment. Based on observations collected at the European Southern Observatory, ESO, the VLT/Kueyen telescope, Paranal, Chile, proposal code: 088.A-0051.The reduced spectrum is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130

  8. The Discovery and Broadband Follow-Up of the Transient Afterglow of GRB 980703

    NASA Technical Reports Server (NTRS)

    Bloom, J. S.; Frail, D. A.; Kulkarni, S. R.; Djorgovski, S. G.; Halpern, J. P.; Marzke, R. O.; Patton, D. R.; Oke, J. B.; Horne, K. D.; Gomer, R.; Goodrich, R.; Campbell, R.; Moriarity-Schieven, G. H.; Redman, R. O.; Feldman, P. A.; Costa, E.; Masetti, N.

    1998-01-01

    We report on the discovery of the radio, infrared, and optical transient coincident with an X-ray transient proposed to be the afterglow of GRB 980703. At later times when the transient has faded below detection, we see an underlying galaxy with R = 22.6; this galaxy is the brightest host galaxy (by nearly 2 mag) of any cosmological gamma-ray burst (GRB) thus far. In keeping with an established trend, the GRB is not significantly offset from the host galaxy. Interpreting the multiwavelength data in the framework of the popular fireball model requires that the synchrotron cooling break was between the optical and X-ray bands on 1998 July 8.5 UT and that the intrinsic extinction of the transient is A(sub v) = 0.9. This is somewhat higher than the extinction for the galaxy as a whole, as estimated from spectroscopy.

  9. An Achromatic Break in the Afterglow of the Short GRB 140903A: Evidence for a Narrow Jet

    NASA Astrophysics Data System (ADS)

    Troja, E.; Sakamoto, T.; Cenko, S. B.; Lien, A.; Gehrels, N.; Castro-Tirado, A. J.; Ricci, R.; Capone, J.; Toy, V.; Kutyrev, A.; Kawai, N.; Cucchiara, A.; Fruchter, A.; Gorosabel, J.; Jeong, S.; Levan, A.; Perley, D.; Sanchez-Ramirez, R.; Tanvir, N.; Veilleux, S.

    2016-08-01

    We report the results of our observing campaign on GRB 140903A, a nearby (z = 0.351) short-duration (T 90 ˜ 0.3 s) gamma-ray burst discovered by Swift. We monitored the X-ray afterglow with Chandra up to 15 days after the burst and detected a steeper decay of the X-ray flux after t j ≈ 1 day. Continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we interpret it as evidence of a narrowly collimated jet. By using the standard fireball model to describe the afterglow evolution, we derive a jet opening angle θ j ≈ 5° and a collimation-corrected total energy release E ≈ 2 × {10}50 erg. We further discuss the nature of the GRB progenitor system. Three main lines disfavor a massive star progenitor: the properties of the prompt gamma-ray emission, the age and low star formation rate of the host galaxy, and the lack of a bright supernova. We conclude that this event likely originated from a compact binary merger.

  10. An Achromatic Break in the Afterglow of the Short GRB 140903A: Evidence for a Narrow Jet

    NASA Astrophysics Data System (ADS)

    Troja, E.; Sakamoto, T.; Cenko, S. B.; Lien, A.; Gehrels, N.; Castro-Tirado, A. J.; Ricci, R.; Capone, J.; Toy, V.; Kutyrev, A.; Kawai, N.; Cucchiara, A.; Fruchter, A.; Gorosabel, J.; Jeong, S.; Levan, A.; Perley, D.; Sanchez-Ramirez, R.; Tanvir, N.; Veilleux, S.

    2016-08-01

    We report the results of our observing campaign on GRB 140903A, a nearby (z = 0.351) short-duration (T 90 ∼ 0.3 s) gamma-ray burst discovered by Swift. We monitored the X-ray afterglow with Chandra up to 15 days after the burst and detected a steeper decay of the X-ray flux after t j ≈ 1 day. Continued monitoring at optical and radio wavelengths showed a similar decay in flux at nearly the same time, and we interpret it as evidence of a narrowly collimated jet. By using the standard fireball model to describe the afterglow evolution, we derive a jet opening angle θ j ≈ 5° and a collimation-corrected total energy release E ≈ 2 × {10}50 erg. We further discuss the nature of the GRB progenitor system. Three main lines disfavor a massive star progenitor: the properties of the prompt gamma-ray emission, the age and low star formation rate of the host galaxy, and the lack of a bright supernova. We conclude that this event likely originated from a compact binary merger.

  11. Short GRB 130603B: Discovery of a jet break in the optical and radio afterglows, and a mysterious late-time X-ray excess

    SciTech Connect

    Fong, W.; Berger, E.; Margutti, R.; Chornock, R.; Migliori, G.; Zauderer, B. A.; Lunnan, R.; Laskar, T.; Metzger, B. D.; Foley, R. J.; Desch, S. J.; Meech, K. J.; Sonnett, S.; Dickey, C.; Hedlund, A.; Harding, P.

    2014-01-10

    We present radio, optical/NIR, and X-ray observations of the afterglow of the short-duration Swift and Konus-Wind GRB 130603B, and uncover a break in the radio and optical bands at ≈0.5 day after the burst, best explained as a jet break with an inferred jet opening angle of ≈4°-8°. GRB 130603B is only the third short GRB with a radio afterglow detection to date, and represents the first time that a jet break has been evident in the radio band. We model the temporal evolution of the spectral energy distribution to determine the burst explosion properties and find an isotropic-equivalent kinetic energy of ≈(0.6-1.7) × 10{sup 51} erg and a circumburst density of ≈5 × 10{sup –3}-30 cm{sup –3}. From the inferred opening angle of GRB 130603B, we calculate beaming-corrected energies of E {sub γ} ≈ (0.5-2) × 10{sup 49} erg and E {sub K} ≈ (0.1-1.6) × 10{sup 49} erg. Along with previous measurements and lower limits we find a median opening angle of ≈10°. Using the all-sky observed rate of 10 Gpc{sup –3} yr{sup –1}, this implies a true short GRB rate of ≈20 yr{sup –1} within 200 Mpc, the Advanced LIGO/VIRGO sensitivity range for neutron star binary mergers. Finally, we uncover evidence for significant excess emission in the X-ray afterglow of GRB 130603B at ≳ 1 day and conclude that the additional energy component could be due to fall-back accretion or spin-down energy from a magnetar formed following the merger.

  12. 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.

  13. Extremely Soft X-Ray Flash as the Indicator of Off-axis Orphan GRB Afterglow

    NASA Astrophysics Data System (ADS)

    Urata, Yuji; Huang, Kuiyun; Yamazaki, Ryo; Sakamoto, Takanori

    2015-06-01

    We verified the off-axis jet model of X-ray flashes (XRFs) and examined a discovery of off-axis orphan gamma-ray burst (GRB) afterglows. The XRF sample was selected on the basis of the following three factors: (1) a constraint on the lower peak energy of the prompt spectrum {E}{obs}{src}, (2) redshift measurements, and (3) multicolor observations of an earlier (or brightening) phase. XRF 020903 was the only sample selected on the basis of these criteria. A complete optical multicolor afterglow light curve of XRF 020903 obtained from archived data and photometric results in the literature showed an achromatic brightening around 0.7 days. An off-axis jet model with a large observing angle (0.21 rad, which is twice the jet opening half-angle, {θ }{jet}) can naturally describe the achromatic brightening and the prompt X-ray spectral properties. This result indicates the existence of off-axis orphan GRB afterglow light curves. Events with a larger viewing angle (\\gt ∼ 2{θ }{jet}) could be discovered using an 8 m class telescope with wide-field imagers such as the Subaru Hyper-Suprime-Cam and the Large Synoptic Survey Telescope.

  14. Optical light curve of GRB 121011A: a textbook for the onset of GRB afterglow in a mixture of ISM and wind-type medium

    NASA Astrophysics Data System (ADS)

    Xin, Li-Ping; Wei, Jian-Yan; Qiu, Yu-Lei; Deng, Jin-Song; Wang, Jing; Han, Xu-Hui

    2016-01-01

    We report the optical observations of GRB 121011A by the 0.8m TNT facility at Xinglong observatory, China. The light curve of the optical afterglow shows a smooth and featureless bump during the epoch of ∼130 s and ∼5000 s with a rising index of 1.57 ± 0.28 before the break time of 539 ± 44 s, and a decaying index of about 1.29 ± 0.07 up to the end of our observations. Moreover, the X-ray light curve decays in a single power-law with a slope of about 1.51 ± 0.03 observed by XRT onboard Swift from 100 s to about 10 000 s after the burst trigger. The featureless optical light curve could be understood as an onset process under the external-shock model. The typical frequency has been below or near the optical one before the deceleration time, and the cooling frequency is located between the optical and X-ray wavelengths. The external medium density has a transition from a mixed stage of ISM and wind-type medium before the peak time to the ISM at the later phase. The joint-analysis of X-ray and optical light curves shows that the emissions from both frequencies are consistent with the prediction of the standard afterglow model without any energy injections, indicating that the central engine has stopped its activity and does not restart anymore after the prompt phase.

  15. Spectroscopy of the optical afterglow of GRB 021004: Origin of the blue-shifted hydrogen lines

    NASA Astrophysics Data System (ADS)

    Starling, R. L. C.; Wijers, R. A. M. J.; Hughes, M. A.; Tanvir, N. R.; Vreeswijk, P. M.; Rol, E.; Wiersema, K.; Salamanca, I.

    2005-07-01

    We present spectra of the afterglow of GRB 021004 taken with WHT ISIS and VLT FORS1 at three epochs spanning 0.49-6.62 days after the burst. Alongside absorption lines from the host galaxy, we identify absorption in HI, SiIV and CIV with blueshifts of up to 2800km s-1 from the explosion centre which we assume originates close to the progenitor. We investigate the origin of the outflowing material and evaluate various possible progenitor models, in particular a binary progenitor consisting of a Wolf-Rayet star and hydrogen-rich companion.

  16. Detailed afterglow modelling and host galaxy properties of the dark GRB 111215A

    NASA Astrophysics Data System (ADS)

    van der Horst, A. J.; Levan, A. J.; Pooley, G. G.; Wiersema, K.; Krühler, T.; Perley, D. A.; Starling, R. L. C.; Curran, P. A.; Tanvir, N. R.; Wijers, R. A. M. J.; Strom, R. G.; Kouveliotou, C.; Hartoog, O. E.; Xu, D.; Fynbo, J. P. U.; Jakobsson, P.

    2015-02-01

    Gamma-ray burst (GRB) 111215A was bright at X-ray and radio frequencies, but not detected in the optical or near-infrared (nIR) down to deep limits. We have observed the GRB afterglow with the Westerbork Synthesis Radio Telescope and Arcminute Microkelvin Imager at radio frequencies, with the William Herschel Telescope and Nordic Optical Telescope in the nIR/optical, and with the Chandra X-ray Observatory. We have combined our data with the Swift X-Ray Telescope monitoring, and radio and millimetre observations from the literature to perform broad-band modelling, and determined the macro- and microphysical parameters of the GRB blast wave. By combining the broad-band modelling results with our nIR upper limits we have put constraints on the extinction in the host galaxy. This is consistent with the optical extinction we have derived from the excess X-ray absorption, and higher than in other dark bursts for which similar modelling work has been performed. We also present deep imaging of the host galaxy with the Keck I telescope, Spitzer Space Telescope, and Hubble Space Telescope (HST), which resulted in a well-constrained photometric redshift, giving credence to the tentative spectroscopic redshift we obtained with the Keck II telescope, and estimates for the stellar mass and star formation rate of the host. Finally, our high-resolution HST images of the host galaxy show that the GRB afterglow position is offset from the brightest regions of the host galaxy, in contrast to studies of optically bright GRBs.

  17. The Achromatic Light Curve of the Optical Afterglow of GRB 030226 at a Redshift of z Approximately 2

    NASA Technical Reports Server (NTRS)

    Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Masetti, N.; Guenther, E.; Stecklum, B.; Lindsay, K.

    2003-01-01

    Abstract. We report on optical and near-infrared (NIR) follow-up observations of the afterglow of GRB 030226, mainly performed with the telescopes at ESO La Silla and Paranal, with additional data obtained at other places. Our first observations started 0.2 days after the burst when the afterglow was at a magnitude of R approximately equal to 19 . One week later the magnitude of the afterglow had fallen to R=25, and at two weeks after the burst it could no longer be detected (R > 26). Our VLT blueband spectra show two absorption line systems at redshifts z = 1.962 +/- 0.001 and at z = 1.986 +/- 0.001, placing the redshift of the burster close to 2. Within our measurement errors no evidence for variations in the line strengths has been found between 0.2 and 1.2 days after the burst. An overabundance of alpha-group elements might indicate that the burst occurred in a chemically young interstellar region shaped by the nucleosynthesis from type II supernovae. The spectral slope of the afterglow shows no signs for cosmic dust along the line of sight in the GRB host galaxy, which itself remained undetected (R > 26.2). At the given redshift no supernova component affected the light from the GRB afterglow, so that the optical transient was essentially only powered by the radiation from the GRB fireball, allowing for a detailed investigation of the color evolution of the afterglow light. In our data set no obvious evidence for color changes has been found before, during, or after the smooth break in the light curve approximately 1 day after the burst. In comparison with investigations by others, our data favor the interpretation that the afterglow began to develop into a homogeneous interstellar medium before the break in the light curve became apparent.

  18. 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.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We report the discovery of the optical and near-infrared counterpart to GRB 001011. The GRB 001011 error box determined by Beppo-SAX was simultaneously imaged in the near-infrared by the 3.58-m. New Technology Telescope and in the optical by the 1.54-m Danish Telescope - 8 hr after the gamma-ray event. We implement the colour-colour discrimination technique proposed by Rhoads (2001) and extend it using near-IR data as well. We present the results provided by an automatic colour-colour discrimination pipe-line developed to discern the different populations of objects present in the GRB 001011 error box. Our software revealed three candidates based on single-epoch images. Second-epoch observations carried out approx. 3.2 days after the burst revealed that the most likely candidate had faded thus identifying it with the counterpart to the GRB. In deep R-band images obtained 7 months after the burst a faint (R=25.38 plus or minus 0.25) elongated object, presumably the host galaxy of GRB 001011, was detected at the position of the afterglow. The GRB 001011 afterglow is the first discovered with the assistance of colour-colour diagram techniques. We discuss the advantages of using this method and its application to boxes determined by future missions.

  19. The mysterious optical afterglow spectrum of GRB 140506A at z = 0.889

    NASA Astrophysics Data System (ADS)

    Fynbo, J. P. U.; Krühler, T.; Leighly, K.; Ledoux, C.; Vreeswijk, P. M.; Schulze, S.; Noterdaeme, P.; Watson, D.; Wijers, R. A. M. J.; Bolmer, J.; Cano, Z.; Christensen, L.; Covino, S.; D'Elia, V.; Flores, H.; Friis, M.; Goldoni, P.; Greiner, J.; Hammer, F.; Hjorth, J.; Jakobsson, P.; Japelj, J.; Kaper, L.; Klose, S.; Knust, F.; Leloudas, G.; Levan, A.; Malesani, D.; Milvang-Jensen, B.; Møller, P.; Nicuesa Guelbenzu, A.; Oates, S.; Pian, E.; Schady, P.; Sparre, M.; Tagliaferri, G.; Tanvir, N.; Thöne, C. C.; de Ugarte Postigo, A.; Vergani, S.; Wiersema, K.; Xu, D.; Zafar, T.

    2014-12-01

    Context. Gamma-ray burst (GRB) afterglows probe sightlines to star-forming regions in distant star-forming galaxies. Here we present a study of the peculiar afterglow spectrum of the z = 0.889Swift GRB 140506A. Aims: Our aim is to understand the origin of the very unusual properties of the absorption along the line of sight. Methods: We analyse spectroscopic observations obtained with the X-shooter spectrograph mounted on the ESO/VLT at two epochs 8.8 h and 33 h after the burst, and with imaging from the GROND instrument. We also present imaging and spectroscopy of the host galaxy obtained with the Magellan telescope. Results: The underlying afterglow appears to be a typical afterglow of a long-duration GRB. However, the material along the line of sight has imprinted very unusual features on the spectrum. First, there is a very broad and strong flux drop below 8000 Å (~4000 Å in the rest frame), which seems to be variable between the two spectroscopic epochs. We can reproduce the flux-drops both as a giant 2175 Å extinction bump and as an effect of multiple scattering on dust grains in a dense environment. Second, we detect absorption lines from excited H i and He i. We also detect molecular absorption from CH+. Conclusions: We interpret the unusual properties of these spectra as reflecting the presence of three distinct regions along the line of sight: the excited He i absorption originates from an H ii-region, whereas the Balmer absorption must originate from an associated photodissociation region. The strong metal line and molecular absorption and the dust extinction must originate from a third, cooler region along the line of sight. The presence of at least three separate regions is reflected in the fact that the different absorption components have different velocities relative to the systemic redshift of the host galaxy. Based on observations carried out under prog. ID 093.A-0069(B) with the X-shooter spectrograph installed at the Cassegrain focus of the

  20. GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

    NASA Technical Reports Server (NTRS)

    Holland, Stephen T.; DePasquale, Massimiliano; Mao, Jirong; Sakamoto, Taka; Shady, Patricia; Covino, Stefano; Yi-Zhong, Fan; Zhi-Ping, Jin; D'Avanzo, Paolo; Antonelli, Angelo; D'Elia, Valerio; Chincarini, Guido; Fiore, Fabrizio; Pandey, Shashi Bhushan

    2011-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift UltraViolet Optical Telescope with ground-based optical and infrared data obtained using the REM and ROTSE telescopes to construct a detailed data set extending from 86 s to approx. 100000 s after the BAT trigger. Our data cover a wide energy range, from 10 keV to 0.77 eV (1.24 A to 16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 5000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.

  1. GRB 081029: A GAMMA-RAY BURST WITH A MULTI-COMPONENT AFTERGLOW

    SciTech Connect

    Holland, Stephen T.; Sakamoto, Takanori; De Pasquale, Massimiliano; Schady, Patricia; Mao, Jirong; Covino, Stefano; Jin, Zhi-Ping; D'Avanzo, Paolo; Chincarini, Guido; Fan, Yi-Zhong; Antonelli, Angelo; D'Elia, Valerio; Fiore, Fabrizio; Pandey, Shashi Bhushan; Cobb, Bethany E.

    2012-01-20

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift UltraViolet/Optical Telescope with ground-based optical and infrared data obtained using the REM, ROTSE, and CTIO 1.3 m telescopes to construct a detailed data set extending from 86 s to {approx}100000 s after the BAT trigger. Our data cover a wide energy range from 10 keV to 0.77 eV (1.24 A-16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 3000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray-burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray-burst jets are complex and will require detailed modeling to fully understand them.

  2. Was the X-ray Afterglow of GRB 970815 Detected, or is 3EG J1621+8203 a Pulsar?

    NASA Astrophysics Data System (ADS)

    Mirabal, Nestor

    2003-09-01

    One of the gamma-ray bursts localized by the RXTE ASM was followed by ASCA and ROSAT HRI pointings. While an X-ray source was detected just outside the ASM error box, it was never associated with the GRB because it was not clearly fading and because no optical afterglow was found. Years later, while attempting to identify an EGRET source whose error ellipse includes the position of GRB 970815, we made deep optical observations of the ASCA and ROSAT source position, which is still blank to a limit V > 24.4. We need a brief Chandra observation to see if the X-ray source is persistent. If not, it was almost certainly the X-ray afterglow of the optically "dark" GRB. If still present, it may be an "off-beam" pulsar counterpart of an EGRET source, and an important target for further study.

  3. THE MAGNETIZATION DEGREE OF THE OUTFLOW POWERING THE HIGHLY POLARIZED REVERSE-SHOCK EMISSION OF GRB 120308A

    SciTech Connect

    Zhang, Shuai; Jin, Zhi-Ping; Wei, Da-Ming E-mail: dmwei@pmo.ac.cn

    2015-01-01

    GRB 120308A, a long duration γ-ray burst (GRB) detected by Swift, was distinguished by a highly polarized early optical afterglow emission that strongly suggests an ordered magnetic field component in the emitting region. In this work, we model the optical and X-ray emission in the reverse and forward shock scenario and show that the strength of the magnetic field in the reverse-shock region is ∼10 times stronger than that in the forward shock region. Consequently, the outflow powering the highly polarized reverse-shock optical emission was mildly magnetized at a degree of σ ∼ a few percent. Considering the plausible magnetic energy dissipation in both the acceleration and prompt emission phases of the GRB outflow, the afterglow data of GRB 120308A provides us with compelling evidence that, at least for some GRBs, a nonignorable fraction of the energy was released in the form of Poynting flux, confirming the finding first made in the reverse-forward shock emission modeling of the optical afterglow of GRB 990123 by Fan et al. in 2002 and Zhang et al. in 2003.

  4. The Radio Afterglow of GRB030329 at Centimetre Wavelengths: Evidence for Multiple Jets or a Structured Jet. Chapter 6

    NASA Technical Reports Server (NTRS)

    Rol, E.; vanderHorst, A. J.; Wijers, R. A. M. J.; Strom, R.; Kaper, L.; Kouveliotou, C.; vandenHeuvel, E. P. J.

    2003-01-01

    We present our centimetre wavelength (1.4, 2.3 and 4.9 GHz) light curves of the afterglow of GRB030329, which were obtained with the Westerbork Synthesis Radio Telescope. Modelling the data according to a collimated afterglow results in a jet-break time t(sub j) of 17 days. This is in contrast with earlier results obtained at higher frequencies, which indicate t(sub j) to be around 10 days. Furthermore, with respect to the afterglow model, some additional flux at the lower frequencies is present when these light curves reach their maximum. We subsequently show that the afterglow can be modelled with two or more components with progressively later jet breaks. From these results we infer that the jet is in fact a structured or a layered jet, where the ejecta with lower Lorentz factors produce additional flux which becomes visible at late times in the lowest frequency bands.

  5. The Afterglows of Swift-era Gamma-ray Bursts. I. Comparing pre-Swift and Swift-era Long/Soft (Type II) GRB Optical Afterglows

    NASA Astrophysics Data System (ADS)

    Kann, D. A.; Klose, S.; Zhang, B.; Malesani, D.; Nakar, E.; Pozanenko, A.; Wilson, A. C.; Butler, N. R.; Jakobsson, P.; Schulze, S.; Andreev, M.; Antonelli, L. A.; Bikmaev, I. F.; Biryukov, V.; Böttcher, M.; Burenin, R. A.; Castro Cerón, J. M.; Castro-Tirado, A. J.; Chincarini, G.; Cobb, B. E.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Della Valle, M.; de Ugarte Postigo, A.; Efimov, Yu.; Ferrero, P.; Fugazza, D.; Fynbo, J. P. U.; Gålfalk, M.; Grundahl, F.; Gorosabel, J.; Gupta, S.; Guziy, S.; Hafizov, B.; Hjorth, J.; Holhjem, K.; Ibrahimov, M.; Im, M.; Israel, G. L.; Jeĺinek, M.; Jensen, B. L.; Karimov, R.; Khamitov, I. M.; Kiziloǧlu, Ü.; Klunko, E.; Kubánek, P.; Kutyrev, A. S.; Laursen, P.; Levan, A. J.; Mannucci, F.; Martin, C. M.; Mescheryakov, A.; Mirabal, N.; Norris, J. P.; Ovaldsen, J.-E.; Paraficz, D.; Pavlenko, E.; Piranomonte, S.; Rossi, A.; Rumyantsev, V.; Salinas, R.; Sergeev, A.; Sharapov, D.; Sollerman, J.; Stecklum, B.; Stella, L.; Tagliaferri, G.; Tanvir, N. R.; Telting, J.; Testa, V.; Updike, A. C.; Volnova, A.; Watson, D.; Wiersema, K.; Xu, D.

    2010-09-01

    We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to 2009 September, for a total of 76 GRBs, and present an additional three pre-Swift GRBs not included in an earlier sample. Furthermore, we publish 840 additional new photometry data points on a total of 42 GRB afterglows, including large data sets for GRBs 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A, and 080810. We analyzed the light curves of all GRBs in the sample and derived spectral energy distributions for the sample with the best data quality, allowing us to estimate the host-galaxy extinction. We transformed the afterglow light curves into an extinction-corrected z = 1 system and compared their luminosities with a sample of pre-Swift afterglows. The results of a former study, which showed that GRB afterglows clustered and exhibited a bimodal distribution in luminosity space, are weakened by the larger sample. We found that the luminosity distribution of the two afterglow samples (Swift-era and pre-Swift) is very similar, and that a subsample for which we were not able to estimate the extinction, which is fainter than the main sample, can be explained by assuming a moderate amount of line-of-sight host extinction. We derived bolometric isotropic energies for all GRBs in our sample, and found only a tentative correlation between the prompt energy release and the optical afterglow luminosity at 1 day after the GRB in the z = 1 system. A comparative study of the optical luminosities of GRB afterglows with echelle spectra (which show a high number of foreground absorbing systems) and those without, reveals no indication that the former are statistically significantly more luminous. Furthermore, we propose the existence of an upper ceiling on afterglow luminosities and study the luminosity distribution at early times, which was not accessible before the advent of the Swift satellite. Most GRBs feature

  6. Happy Birthday Swift: Ultra-long GRB 141121A and Its Broadband Afterglow

    NASA Astrophysics Data System (ADS)

    Cucchiara, A.; Veres, P.; Corsi, A.; Cenko, S. B.; Perley, D. A.; Lien, A.; Marshall, F. E.; Pagani, C.; Toy, V. L.; Capone, J. I.; Frail, D. A.; Horesh, A.; Modjaz, M.; Butler, N. R.; Littlejohns, O. M.; Watson, A. M.; Kutyrev, A. S.; Lee, W. H.; Richer, M. G.; Klein, C. R.; Fox, O. D.; Prochaska, J. X.; Bloom, J. S.; Troja, E.; Ramirez-Ruiz, E.; de Diego, J. A.; Georgiev, L.; González, J.; Román-Zúñiga, C. G.; Gehrels, N.; Moseley, H.

    2015-10-01

    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 Eγ,iso = 8.0 × 1052 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 three 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.

  7. Happy Birthday Swift: Ultra-long GRB 141121A and Its Broadband Afterglow

    NASA Astrophysics Data System (ADS)

    Cucchiara, A.; Veres, P.; Corsi, A.; Cenko, S. B.; Perley, D. A.; Lien, A.; Marshall, F. E.; Pagani, C.; Toy, V. L.; Capone, J. I.; Frail, D. A.; Horesh, A.; Modjaz, M.; Butler, N. R.; Littlejohns, O. M.; Watson, A. M.; Kutyrev, A. S.; Lee, W. H.; Richer, M. G.; Klein, C. R.; Fox, O. D.; Prochaska, J. X.; Bloom, J. S.; Troja, E.; Ramirez-Ruiz, E.; de Diego, J. A.; Georgiev, L.; González, J.; Román-Zúñiga, C. G.; Gehrels, N.; Moseley, H.

    2015-10-01

    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 Eγ,iso = 8.0 × 1052 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 three 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.

  8. GRB 081029: A Gamma-Ray Burst with a Multi-Component Afterglow

    NASA Technical Reports Server (NTRS)

    Holland, Stephen T.; De Pasquale, Massimiliano; Mao, Jirong; Sakamoto, Takanori; Schady, Patricia; Covino, Stefano; Fan, Yi-Zhong; Jin, Zhi-Ping; D'Avanzo, Paolo; Antonelli, Angelo; D'Elia, Valerio; Ohincarini, Guido; Fiore, Fabrizio; Pandey, Shashi Bhushan; Cobb, Bethany E.

    2012-01-01

    We present an analysis of the unusual optical light curve of the gamma-ray burst GRB 081029, a long-soft burst with a redshift of z = 3.8479. We combine X-ray and optical observations from the Swift X-Ray Telescope and the Swift Ultra Violet/Optical Telescope with ground-based optical and infrared data obtained using the REM, ROTSE, and CTIO 1.3-m telescopes to construct a detailed data set extending from 86 s to approx.100,000 s after the BAT trigger. Our data covers a wide energy range, from 10 keV to 0.77 eV (1.24 A to 16000 A). The X-ray afterglow shows a shallow initial decay followed by a rapid decay starting at about 18,000 s. The optical and infrared afterglow, however, shows an uncharacteristic rise at about 3000 s that does not correspond to any feature in the X-ray light curve. Our data are not consistent with synchrotron radiation from a jet interacting with an external medium, a two-component jet, or continuous energy injection from the central engine. We find that the optical light curves can be broadly explained by a collision between two ejecta shells within a two-component jet. A growing number of gamma-ray burst afterglows are consistent with complex jets, which suggests that some (or all) gamma-ray burst jets are complex and will require detailed modelling to fully understand them.injection

  9. GRB 050502B optical afterglow: a jet-break at high redshift

    NASA Astrophysics Data System (ADS)

    Afonso, P.; Greiner, J.; Pian, E.; Covino, S.; Malesani, D.; Küpcü Yoldaş, A.; Krühler, T.; Clemens, C.; McBreen, S.; Rau, A.; Giannios, D.; Hjorth, J.

    2011-02-01

    Aims: Swift GRB 050502B is well known for the very bright flare displayed in its X-ray light curve. Despite extensive studies, however, the optical light curve has never been discussed and its redshift is unconstrained. Possible correlations between optical and X-ray data are analysed. Methods: Photometric data from TNG in the R and I bands were used to compare the optical afterglow with the X-ray light curve. The HyperZ package and a late-time VLT host observation were used to derive redshift estimates. Results: The I-band afterglow decay followed a power law of index α = 2.1±0.6, after a late break at ~ 1.3×105 s. The R-I colour is remarkably red and the broadband spectral index βOX = 0.9±0.1 is consistent with the X-ray spectral slope βX. Although a photometric redshift of z > 4 is the most conservative result to consider, a photometric redshift of z = 5.2±0.3 is suggested with no extinction in the host, based on which an isotropic energy Eγ,iso = (3.8±0.7)×1052 erg and a jet opening angle θ ~ 3.7° are subsequently derived. Conclusions: The combined X-ray and optical data suggest an achromatic break, which we interpret as a jet-break. The post jet-break slope roughly obeys the closure relation for the jet's slow cooling model. Because of the afterglow's very red colour, in order for the redshift to be low (z < 1), extinction must be significantly high if present in the host. Since the optical-to-X-ray index is consistent with the X-ray spectrum, and there is no XRT evidence for excess NH, GRB 050502B was likely at high redshift. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (programme AOT11-59) and with ESO Telescopes at the La Silla Paranal Observatories under programme ID 177.A-0591.

  10. Probing the bright radio flare and afterglow of GRB 130427A with the Arcminute Microkelvin Imager

    NASA Astrophysics Data System (ADS)

    Anderson, G. E.; van der Horst, A. J.; Staley, T. D.; Fender, R. P.; Wijers, R. A. M. J.; Scaife, A. M. M.; Rumsey, C.; Titterington, D. J.; Rowlinson, A.; Saunders, R. D. E.

    2014-05-01

    We present one of the best sampled early-time light curves of a gamma-ray burst (GRB) at radio wavelengths. Using the Arcminute Mircrokelvin Imager (AMI), we observed GRB 130427A at the central frequency of 15.7 GHz between 0.36 and 59.32 d post-burst. These results yield one of the earliest radio detections of a GRB and demonstrate a clear rise in flux less than one day after the γ-ray trigger followed by a rapid decline. This early-time radio emission probably originates in the GRB reverse shock so our AMI light curve reveals the first ever confirmed detection of a reverse shock peak in the radio domain. At later times (about 3.2 d post-burst), the rate of decline decreases, indicating that the forward shock component has begun to dominate the light curve. Comparisons of the AMI light curve with modelling conducted by Perley et al. show that the most likely explanation of the early-time 15.7 GHz peak is caused by the self-absorption turn-over frequency, rather than the peak frequency, of the reverse shock moving through the observing bands.

  11. A two-step energy injection explanation for the rebrightenings of the multi-band afterglow of GRB 081029

    NASA Astrophysics Data System (ADS)

    Yu, Yong-Bo; Huang, Yong-Feng

    2013-06-01

    The afterglow of GRB 081029 showed unusual behavior, with a significant rebrightening being observed at the optical wavelength at about 3000 s after the burst. One possible explanation is that the rebrightening resulted from an energy injection. Here we present a detailed numerical study of the energy injection process and interpret the X-ray and optical afterglow light curves of GRB 081029. In our model, we have assumed two periods of energy injection, each with a constant injection power. One injection starts at 2.8 × 103 s and lasts for about 2500 s, with a power of 7.0 × 1047 erg s-1. This energy injection mainly accounts for the rapid rebrightening at about 3000 s. The other injection starts at 8.0 × 103 s and lasts for about 5000 s. The injection power is 3.5 × 1047 erg s-1. This energy injection can help to explain the slight rebrightening at about 10 000 s. It is shown that the observed optical afterglow, especially the marked rebrightening at about 3000 s, can be reproduced well. In the X-ray band, the predicted amplitude of the rebrightening is much shallower, which is also consistent with the observed X-ray afterglow light curve. It is argued that the two periods of energy injection can be produced by clumpy materials falling onto the central compact object of the burster, which leads to an enhancement of accretion and gives rise to a strong temporary outflow.

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

    SciTech Connect

    Perley, D. A.; Metzger, B. D.; Butler, N. R.; Bloom, J. S.; Miller, A. A.; Filippenko, A. V.; Li, W.; Granot, J.; Sakamoto, T.; Gehrels, N.; Ramirez-Ruiz, E.; Bunker, A.; Chen, H.-W.; Glazebrook, K.; Hall, P. B.; Hurley, K. C.; Kocevski, D.; Norris, J.

    2009-05-10

    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, 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.

  13. Prompt and Afterglow Emission Properties of Gamma-Ray Bursts with Spectroscopically Identified Supernovae

    NASA Technical Reports Server (NTRS)

    Kaneko, Yuki; Ramirez-Ruiz, Enrico; Patel, Sandeep K.; Kouveliotou, Chryssa; Granot, Jonathan; Rol, Evert; Woosley, Stan; in'tZand, Jean J. M.; vanderHorst, Alexander; Wijers, Ralph A. M. J.; Strom, Richard

    2006-01-01

    We present a detailed spectral analysis of the prompt and afterglow emission of four nearby GRBs (GRBs 980425, 030329, 031203, and 060218) that were spectroscopically found to be associated with type Ib/c supernovae. For each event, we investigated its spectral and luminosity evolution and estimated the total energy budget based on the broadband observations. We discuss the properties of the four events in comparison to general burst population, and infer the physical parameters involved in creation of these nearby GRB-SN events

  14. X-Ray Spectral Components Observed in the Afterglow of GRB 130925A

    NASA Technical Reports Server (NTRS)

    Bellm, Eric C.; Barriere, Nicolas M.; Bhalerao, Varun; Boggs, Steven E.; Cenko, S. Bradley; Christensen, Finn E.; Craig, William W.; Forster, Karl; Fryer, Chris L.; Hailey, Charles J.; Harrison, Fiona A.; Horesh, Assaf; Kouveliotou, Chryssa; Madsen, Kristin K.; Miller, Jon M.; Ofek, Eran O.; Perley, Daniel A.; Rana, Vikram R.; Miller, Jon M.; Stern, Daniel; Tomsick, John A.; Zhang, William W.

    2014-01-01

    We have identified spectral features in the late-time X-ray afterglow of the unusually long, slow-decaying GRB 130925A using NuSTAR, Swift/X-Ray Telescope, and Chandra. A spectral component in addition to an absorbed power law is required at greater than 4 less than 1 significance, and its spectral shape varies between two observation epochs at 2 x 10 (sup 5) and 10 (sup 6) seconds after the burst. Several models can fit this additional component, each with very different physical implications. A broad, resolved Gaussian absorption feature of several kiloelectronvolts width improves the fit, but it is poorly constrained in the second epoch. An additive blackbody or second power-law component provide better fits. Both are challenging to interpret: the blackbody radius is near the scale of a compact remnant (10 (sup 8) centimeters), while the second power-law component requires an unobserved high-energy cutoff in order to be consistent with the non-detection by Fermi/Large Area Telescope.

  15. Emission spectrum of a sporadic fireball afterglow

    NASA Astrophysics Data System (ADS)

    Madiedo, J.; Trigo-Rodríguez, J.

    2014-07-01

    A mag. -11 fireball was imaged over southern Spain on April 14, 2013 at 22:35:49.8 ± 0.1s UTC. Its emission spectrum was also obtained. This event was assigned the SPMN code 140413 after the recording date. By the end of its atmospheric path, it exhibited a very bright flare which resulted in a persistent train whose spectrum was recorded. Here we present a preliminary analysis of this event and focus special attention on the evolution of the main emission lines in the spectrum of the afterglow. An array of low-lux CCD video devices (models 902H and 902H Ultimate from Watec Co.) operating from our stations at Sevilla and El Arenosillo was employed to record the SPMN140413 fireball. The operation of these systems is explained in [1,2]. Some of these are configured as spectrographs by attaching holographic diffraction gratings (1000 lines/mm) to the objective lens [3]. To calculate the atmospheric trajectory, radiant, and orbit we have employed our AMALTHEA software, which follows the planes intersection method [4]. The spectrum was analyzed with our CHIMET application [5]. The parent meteoroid impacted the atmosphere with an initial velocity of 28.9 ± 0.3 km/s and the fireball began at a height of 104.4 ± 0.5 km. The event ended at 80.7 ± 0.5 km above the ground level, with the main flare taking place at 83 ± 0.5 km. The calculated radiant and orbital parameters confirm the sporadic nature of the bolide. The calibrated emission spectrum shows that the most important contributions correspond to the Na I-1 (588.9 nm) and Mg I-2 (517.2 nm) multiplets. In the ultraviolet, the contribution from the H and K lines from Ca was also identified. As usual in meteor spectra, most of the lines correspond to Fe I. The train spectrum was recorded during about 0.12 seconds. This provided the evolution with time of the intensity of the emission lines in this signal. The contributions from Mg I, Na I, Ca I, Fe I, Ca II, and O I were identified in the afterglow, with the Na I-1

  16. Probing a Gamma-Ray Burst Progenitor at a Redshift of z = 2: A Comprehensive Observing Campaign Campaign of the Afterglow of GRB 030226

    NASA Technical Reports Server (NTRS)

    Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Ries, C.; Masetti, N.; Malesani, D.; Guenther, E.

    2004-01-01

    We report results from a comprehensive follow-up observing campaign of the afterglow of GRB 030226 including VLT spectroscopy, VLT polarimetry, and Chandra X-ray observations. In addition, we present BOOTES-1 wide-field observations at the time of the occurrence of the burst. First observations at ESO started 0.2 days after the event when the gamma ray burst (GRB) afterglow was at a magnitude of R approximately 19 and continued until the afterglow had faded below the detection threshold (R greater than 26). No underlying host galaxy was found. The optical light curve shows a break around 0.8 days after the burst, which is achromatic within the observational errors, supporting the view that it was due to a jetted explosion. Close to the break time the degree of linear polarization of the afterglow light was less than 1.1%, which favors a uniform-jet model rather than a structured one. VLT spectra show two absorption line systems at redshifts z = 1.962 plus or minus 0.001 and 1.986 plus or minus 0.001, placing the lower limit for the redshift of the GRB close to 2. We emphasize that the kinematics and the composition of the absorbing clouds responsible for these line systems are very similar to those observed in the afterglow of GRB 021004. This corroborates the picture in which at least some GRBs are physically related to the explosion of a Wolf-Rayet star.

  17. ON THE FORMATION OF Lyalpha EMISSION FROM RESONANTLY SCATTERED CONTINUUM PHOTONS OF GAMMA-RAY BURST's AFTERGLOW

    SciTech Connect

    Xu Wen; Wu Xiangping

    2010-02-20

    The continuum spectrum of gamma-ray burst's (GRB) afterglow at Lyalpha wavelength is known to be otherwise featureless except for the existence of a pair of smooth damping wings. Resonant scattering of photons with the ambient neutral hydrogen around the GRB may alter this picture. We study the formation and evolution of the spectral imprint of these resonantly scattered photons in the context of GRB's afterglow. Based on an analytic model that includes photons that are scattered only once, as well as a complete treatment of all the scatterings using Monte Carlo simulations, we are able to calculate the spectrum and luminosity of this Lyalpha emission from a very early moment up to a late epoch. We find that the amount, the motion, and the geometry of the neutral hydrogen around the GRB, together with the time behavior of the source are the crucial factors that affect the predicted luminosity and spectral profile. The flux of the Lyalpha emission is found to be mainly contributed by photons that are scattered only once. The flux is of the order 10{sup -4}-10{sup -9} relative to the undecayed maximum flux of the transmitted continuum, making the feature negligible but potentially observable. If not obscured by the host galaxy's damped Lyalpha absorption systems or intergalactic neutral hydrogen, the feature may appear sometime from 1 hr to several years when the directly transmitted light has faded away. This scattered emission feature can be distinguished from Lyalpha photons of other origins by its luminosity evolution and by its gradual narrowing of profile with time. The typical timescale for spectral variance is that of the light crossing time of a hydrogen clump close to the GRB. If observed, the resonant peaks' time-dependent behavior is a scanning probe on the distribution of neutral hydrogen in GRB's immediate neighborhood.

  18. Coasting External Shock in Wind Medium: An Origin for the X-ray Plateau Decay Component in Swift GRB Afterglows

    NASA Astrophysics Data System (ADS)

    Shen, Rongfeng; Matzner, C. D.

    2012-01-01

    The plateaus observed in about one half of the early X-ray afterglows are the most puzzling feature in gamma-ray bursts (GRBs) detected by Swift. By analyzing the temporal and spectral indices of a large X-ray plateau sample, we find that 55% can be explained by external, forward shock synchrotron emission produced by a relativistic ejecta coasting in a ρ r-2, wind-like medium; no energy injection into the shock is needed. After the ejecta collects enough medium and transitions to the adiabatic, decelerating blastwave phase, it produces the post-plateau decay. For those bursts consistent with this model, we find an upper limit for the initial Lorentz factor of the ejecta, Γ0 ≤ 46 (ɛe/0.1)-0.24 (ɛB/0.01)0.17 the isotropic equivalent total ejecta energy is Eiso 1053 (ɛe/0.1)-1.3 (ɛB/0.01)-0.09 (tb/104 s) erg, where ɛe and ɛB are the fractions of the total energy at the shock downstream that are carried by electrons and the magnetic field, respectively, and tb is the end of the plateau. Our finding supports Wolf-Rayet stars as the progenitor stars of some GRBs. It raises intriguing questions about the origin of an intermediate-Γ0 ejecta, which we speculate is connected to the GRB jet emergence from its host star. For the remaining 45% of the sample, the post-plateau decline is too rapid to be explained in the coasting-in-wind model, and energy injection appears to be required.

  19. Phenomenology of reverse-shock emission in the optical afterglows of gamma-ray bursts

    SciTech Connect

    Japelj, J.; Kopač, D.; Gomboc, A.; Kobayashi, S.; Harrison, R.; Virgili, F. J.; Mundell, C. G.; Guidorzi, C.; Melandri, A. E-mail: andreja.gomboc@fmf.uni-lj.si

    2014-04-20

    We use a parent sample of 118 gamma-ray burst (GRB) afterglows, with known redshift and host galaxy extinction, to separate afterglows with and without signatures of dominant reverse-shock (RS) emission and to determine which physical conditions lead to a prominent reverse-shock emission. We identify 10 GRBs with reverse-shock signatures: 990123, 021004, 021211, 060908, 061126, 080319B, 081007, 090102, 090424, and 130427A. By modeling their optical afterglows with reverse- and forward-shock analytic light curves and using Monte Carlo simulations, we estimate the parameter space of the physical quantities describing the ejecta and circumburst medium. We find that physical properties cover a wide parameter space and do not seem to cluster around any preferential values. Comparing the rest-frame optical, X-ray, and high-energy properties of the larger sample of non-RS-dominated GRBs, we show that the early-time (<1 ks) optical spectral luminosity, X-ray afterglow luminosity, and γ-ray energy output of our reverse-shock dominated sample do not differ significantly from the general population at early times. However, the GRBs with dominant reverse-shock emission have fainter than average optical forward-shock emission at late times (>10 ks). We find that GRBs with an identifiable reverse-shock component show a high magnetization parameter R {sub B} = ε{sub B,r}/ε{sub B,f} ∼ 2-10{sup 4}. Our results are in agreement with the mildly magnetized baryonic jet model of GRBs.

  20. DISCOVERY AND REDSHIFT OF AN OPTICAL AFTERGLOW IN 71 deg{sup 2}: iPTF13bxl AND GRB 130702A

    SciTech Connect

    Singer, Leo P.; Brown, Duncan A.; Bradley Cenko, S.; Gehrels, Neil; McEnery, Julie; Kasliwal, Mansi M.; Mulchaey, John; Perley, Daniel A.; Kulkarni, S. R.; Bellm, Eric; Barlow, Tom; Cao, Yi; Horesh, Assaf; Ofek, Eran O.; Arcavi, Iair; Nugent, Peter E.; Bloom, Joshua S.; Corsi, Alessandra; Frail, Dale A.; Masci, Frank J.; and others

    2013-10-20

    We report the discovery of the optical afterglow of the γ-ray burst (GRB) 130702A, identified upon searching 71 deg{sup 2} surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization. Discovered and characterized by the intermediate Palomar Transient Factory, iPTF13bxl is the first afterglow discovered solely based on a GBM localization. Real-time image subtraction, machine learning, human vetting, and rapid response multi-wavelength follow-up enabled us to quickly narrow a list of 27,004 optical transient candidates to a single afterglow-like source. Detection of a new, fading X-ray source by Swift and a radio counterpart by CARMA and the Very Large Array confirmed the association between iPTF13bxl and GRB 130702A. Spectroscopy with the Magellan and Palomar 200 inch telescopes showed the afterglow to be at a redshift of z = 0.145, placing GRB 130702A among the lowest redshift GRBs detected to date. The prompt γ-ray energy release and afterglow luminosity are intermediate between typical cosmological GRBs and nearby sub-luminous events such as GRB 980425 and GRB 060218. The bright afterglow and emerging supernova offer an opportunity for extensive panchromatic follow-up. Our discovery of iPTF13bxl demonstrates the first observational proof-of-principle for ∼10 Fermi-iPTF localizations annually. Furthermore, it represents an important step toward overcoming the challenges inherent in uncovering faint optical counterparts to comparably localized gravitational wave events in the Advanced LIGO and Virgo era.

  1. Detailed optical and near-infrared polarimetry, spectroscopy and broad-band photometry of the afterglow of GRB 091018: polarization evolution

    NASA Astrophysics Data System (ADS)

    Wiersema, K.; Curran, P. A.; Krühler, T.; Melandri, A.; Rol, E.; Starling, R. L. C.; Tanvir, N. R.; van der Horst, A. J.; Covino, S.; Fynbo, J. P. U.; Goldoni, P.; Gorosabel, J.; Hjorth, J.; Klose, S.; Mundell, C. G.; O'Brien, P. T.; Palazzi, E.; Wijers, R. A. M. J.; D'Elia, V.; Evans, P. A.; Filgas, R.; Gomboc, A.; Greiner, J.; Guidorzi, C.; Kaper, L.; Kobayashi, S.; Kouveliotou, C.; Levan, A. J.; Rossi, A.; Rowlinson, A.; Steele, I. A.; de Ugarte Postigo, A.; Vergani, S. D.

    2012-10-01

    Follow-up observations of large numbers of gamma-ray burst (GRB) afterglows, facilitated by the Swift satellite, have produced a large sample of spectral energy distributions and light curves, from which their basic micro- and macro-physical parameters can in principle be derived. However, a number of phenomena have been observed that defy explanation by simple versions of the standard fireball model, leading to a variety of new models. Polarimetry can be a major independent diagnostic of afterglow physics, probing the magnetic field properties and internal structure of the GRB jets. In this paper we present the first high-quality multi-night polarimetric light curve of a Swift GRB afterglow, aimed at providing a well-calibrated data set of a typical afterglow to serve as a benchmark system for modelling afterglow polarization behaviour. In particular, our data set of the afterglow of GRB 091018 (at redshift z = 0.971) comprises optical linear polarimetry (R band, 0.13-2.3 d after burst); circular polarimetry (R band) and near-infrared linear polarimetry (Ks band). We add to that high-quality optical and near-infrared broad-band light curves and spectral energy distributions as well as afterglow spectroscopy. The linear polarization varies between 0 and 3 per cent, with both long and short time-scale variability visible. We find an achromatic break in the afterglow light curve, which corresponds to features in the polarimetric curve. We find that the data can be reproduced by jet break models only if an additional polarized component of unknown nature is present in the polarimetric curve. We probe the ordered magnetic field component in the afterglow through our deep circular polarimetry, finding Pcirc < 0.15 per cent (2σ), the deepest limit yet for a GRB afterglow, suggesting ordered fields are weak, if at all present. Our simultaneous R- and Ks-band polarimetry shows that dust-induced polarization in the host galaxy is likely negligible.

  2. Hubble Space Telescope Observations of the Afterglow, Supernova, and Host Galaxy Associated with the Extremely Bright GRB 130427A

    NASA Astrophysics Data System (ADS)

    Levan, A. J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; Cenko, S. B.; Fynbo, J. P. U.; Kouveliotou, C.; Pe'er, A.; Misra, K.; Wiersema, K.

    2014-09-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E iso > 1054 erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ~17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v ph ~ 15, 000 km s-1). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v ph ~ 30, 000 km s-1), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ~4 kpc from the nucleus of a moderately star forming (1 M ⊙ yr-1), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  3. Hubble space telescope observations of the afterglow, supernova, and host galaxy associated with the extremely bright GRB 130427A

    SciTech Connect

    Levan, A. J.; Tanvir, N. R.; Wiersema, K.; Fruchter, A. S.; Hounsell, R. A.; Graham, J.; Hjorth, J.; Fynbo, J. P. U.; Pian, E.; Mazzali, P.; Perley, D. A.; Cano, Z.; Cenko, S. B.; Kouveliotou, C.; Misra, K.

    2014-09-10

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst (GRB), GRB 130427A. At z = 0.34, this burst affords an excellent opportunity to study the supernova (SN) and host galaxy associated with an intrinsically extremely luminous burst (E {sub iso} > 10{sup 54} erg): more luminous than any previous GRB with a spectroscopically associated SN. We use the combination of the image quality, UV capability, and invariant point-spread function of HST to provide the best possible separation of the afterglow, host, and SN contributions to the observed light ∼17 rest-frame days after the burst, utilizing a host subtraction spectrum obtained one year later. Advanced Camera for Surveys grism observations show that the associated SN, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, v {sub ph} ∼ 15, 000 km s{sup –1}). The positions of the bluer features are better matched by the higher velocity SN 2010bh (v {sub ph} ∼ 30, 000 km s{sup –1}), but this SN is significantly fainter and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated ∼4 kpc from the nucleus of a moderately star forming (1 M {sub ☉} yr{sup –1}), possibly interacting disk galaxy. The absolute magnitude, physical size, and morphology of this galaxy, as well as the location of the GRB within it, are also strikingly similar to those of GRB 980425/SN 1998bw. The similarity of the SNe and environment from both the most luminous and least luminous GRBs suggests that broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  4. Search for VHE emission from GRB with Milagro

    SciTech Connect

    Saz Parkinson, P.M.

    2005-02-21

    The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high-energy particles impacting in the Earth's atmosphere. Milagro is uniquely capable of searching for very high-energy emission from gamma-ray bursts (GRB) during the prompt emission phase because of its wide field of view and high duty cycle, monitoring the northern sky almost continuously in the 100 GeV to 100 TeV energy range. 33 satellite-triggered GRB have occurred within the field of view of Milagro between January 2000 and December 2003. We have searched for counterparts to these GRB and found no significant emission from any of these burst positions. In the case of GRB 010921, the redshift is low enough (0.45) that our upper limit on the fluence places an observational constraint on potential GRB models.

  5. Early-time VLA Observations and Broadband Afterglow Analysis of the Fermi/LAT Detected GRB 130907A

    NASA Astrophysics Data System (ADS)

    Veres, Péter; Corsi, Alessandra; Frail, Dale A.; Cenko, S. Bradley; Perley, Daniel A.

    2015-09-01

    We present multi-wavelength observations of the hyper-energetic gamma-ray burst (GRB) 130907A, a Swift-discovered burst with early radio observations starting at ≈4 hr after the γ-ray trigger. GRB 130907A was also detected by the Fermi/LAT instrument and at late times showed a strong spectral evolution in X-rays. We focus on the early-time radio observations, especially at >10 GHz, to attempt to identify reverse shock signatures. While our radio follow-up of GRB 130907A ranks among the earliest observations of a GRB with the Karl G. Jansky Very Large Array, we did not see an unambiguous signature of a reverse shock. While a model with both reverse and forward shock can correctly describe the observations, the data is not constraining enough to decide upon the presence of the reverse-shock component. We model the broadband data using a simple forward-shock synchrotron scenario with a transition from a wind environment to a constant density interstellar medium (ISM) in order to account for the observed features. Within the confines of this model, we also derive the underlying physical parameters of the fireball, which are within typical ranges except for the wind density parameter (A*), which is higher than those for bursts with wind-ISM transition, but typical for the general population of bursts. We note the importance of early-time radio observations of the afterglow (and of well-sampled light curves) for unambiguously identifying the potential contribution of the reverse shock.

  6. Hubble Space Telescope Observations of the Afterglow, Supernova and Host Galaxy Associated with the Extremely Bright GRB 130427A

    NASA Technical Reports Server (NTRS)

    Levan, A.J.; Tanvir, N. R.; Fruchter, A. S.; Hjorth, J.; Pian, E.; Mazzali, P.; Hounsell, R. A.; Perley, D. A.; Cano, Z.; Graham, J.; Cenko, S. B.; Fynbo, J. P. U.; Kouveliotou, C.; Pe'er, A.; Misra, K.; Wiersema, K.

    2014-01-01

    We present Hubble Space Telescope (HST) observations of the exceptionally bright and luminous Swift gamma-ray burst, GRB 130427A. At z=0.34 this burst affords an excellent opportunity to study the supernova and host galaxy associated with an intrinsically extremely luminous burst (E(sub iso) greater than 10(exp 54) erg): more luminous than any previous GRB with a spectroscopically associated supernova. We use the combination of the image quality, UV capability and and invariant PSF of HST to provide the best possible separation of the afterglow, host and supernova contributions to the observed light approximately 17 rest-frame days after the burst utilising a host subtraction spectrum obtained 1 year later. Advanced Camera for Surveys (ACS) grism observations show that the associated supernova, SN 2013cq, has an overall spectral shape and luminosity similar to SN 1998bw (with a photospheric velocity, vph approximately 15,000 kilometers per second). The positions of the bluer features are better matched by the higher velocity SN 2010bh (vph approximately 30,000 kilometers per second), but SN 2010bh (vph approximately 30,000 kilometers per second but this SN is significantly fainter, and fails to reproduce the overall spectral shape, perhaps indicative of velocity structure in the ejecta. We find that the burst originated approximately 4 kpc from the nucleus of a moderately star forming (1 Solar Mass yr(exp-1)), possibly interacting disc galaxy. The absolute magnitude, physical size and morphology of this galaxy, as well as the location of the GRB within it are also strikingly similar to those of GRB980425SN 1998bw. The similarity of supernovae and environment from both the most luminous and least luminous GRBs suggests broadly similar progenitor stars can create GRBs across six orders of magnitude in isotropic energy.

  7. CONSTRAINTS ON VERY HIGH ENERGY EMISSION FROM GRB 130427A

    SciTech Connect

    Aliu, E.; Errando, M.; Aune, T.; Barnacka, A.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Benbow, W.; Cerruti, M.; Berger, K.; Biteau, J.; Byrum, K.; Cardenzana, J. V; Dickinson, H. J.; Eisch, J. D.; Chen, X.; Ciupik, L.; Connaughton, V.; Cui, W.; Falcone, A. E-mail: sjzhu@umd.edu; and others

    2014-11-01

    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 also 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. 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.

  8. Confronting GRB prompt emission with a model for subphotospheric dissipation

    NASA Astrophysics Data System (ADS)

    Ahlgren, Björn; Larsson, Josefin; Nymark, Tanja; Ryde, Felix; Pe'er, Asaf

    2015-11-01

    The origin of the prompt emission in gamma-ray bursts (GRBs) is still an unsolved problem and several different mechanisms have been suggested. Here, 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. We show that this model can describe 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 suggest that the main difference between these two types of bursts is the optical depth at the dissipation site.

  9. Photometry and spectroscopy of GRB 060526: a detailed study of the afterglow and host galaxy of a z = 3.2 gamma-ray burst

    NASA Astrophysics Data System (ADS)

    Thöne, C. C.; Kann, D. A.; Jóhannesson, G.; Selj, J. H.; Jaunsen, A. O.; Fynbo, J. P. U.; Akerlof, C. W.; Baliyan, K. S.; Bartolini, C.; Bikmaev, I. F.; Bloom, J. S.; Burenin, R. A.; Cobb, B. E.; Covino, S.; Curran, P. A.; Dahle, H.; Ferrero, A.; Foley, S.; French, J.; Fruchter, A. S.; Ganesh, S.; Graham, J. F.; Greco, G.; Guarnieri, A.; Hanlon, L.; Hjorth, J.; Ibrahimov, M.; Israel, G. L.; Jakobsson, P.; Jelínek, M.; Jensen, B. L.; Jørgensen, U. G.; Khamitov, I. M.; Koch, T. S.; Levan, A. J.; Malesani, D.; Masetti, N.; Meehan, S.; Melady, G.; Nanni, D.; Näränen, J.; Pakstiene, E.; Pavlinsky, M. N.; Perley, D. A.; Piccioni, A.; Pizzichini, G.; Pozanenko, A.; Roming, P. W. A.; Rujopakarn, W.; Rumyantsev, V.; Rykoff, E. S.; Sharapov, D.; Starr, D.; Sunyaev, R. A.; Swan, H.; Tanvir, N. R.; Terra, F.; de Ugarte Postigo, A.; Vreeswijk, P. M.; Wilson, A. C.; Yost, S. A.; Yuan, F.

    2010-11-01

    Aims: With this paper we want to investigate the highly variable afterglow light curve and environment of gamma-ray burst (GRB) 060526 at z = 3.221. Methods: We present one of the largest photometric datasets ever obtained for a GRB afterglow, consisting of multi-color photometric data from the ultraviolet to the near infrared. The data set contains 412 data points in total to which we add additional data from the literature. Furthermore, we present low-resolution high signal-to-noise spectra of the afterglow. The afterglow light curve is modeled with both an analytical model using broken power law fits and with a broad-band numerical model which includes energy injections. The absorption lines detected in the spectra are used to derive column densities using a multi-ion single-component curve-of-growth analysis from which we derive the metallicity of the host of GRB 060526. Results: The temporal behaviour of the afterglow follows a double broken power law with breaks at t = 0.090 ± 0.005 and t = 2.401 ± 0.061 days. It shows deviations from the smooth set of power laws that can be modeled by additional energy injections from the central engine, although some significant microvariability remains. The broadband spectral-energy distribution of the afterglow shows no significant extinction along the line of sight. The metallicity derived from S ii and Fe ii of [S/H] = -0.57 ± 0.25 and [Fe/H] = -1.09 ± 0.24 is relatively high for a galaxy at that redshift but comparable to the metallicity of other GRB hosts at similar redshifts. At the position of the afterglow, no host is detected to F775W(AB) = 28.5 mag with the HST, implying an absolute magnitude of the host M(1500 Å) > -18.3 mag which is fainter than most long-duration hosts, although the GRB may be associated with a faint galaxy at a distance of 11 kpc. Based in part on observations obtained with the European Southern Observatory's Very Large Telescope under proposals 077.D-0661 (PI: Vreeswijk) and 177.A-0591

  10. 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.; Gehrels, N.

    2014-01-01

    The mechanism that causes the prompt-emission episode of gamma-ray bursts (GRBs) is still widely debated despite there being thousands of prompt detections. The favoured internal shock model relates this emission to synchrotron radiation. However, it does not always explain the spectral indices of the shape of the spectrum, which is often fit with empirical functions, such as the Band function. Multi-wavelength observations are therefore required to help investigate the possible underlying mechanisms that causes the prompt emission. We present GRB 121217A, for which we were able to observe its near-infrared (NIR) emission during a secondary prompt-emission episode with the Gamma-Ray burst Optical Near-infrared Detector (GROND) in combination with the Swift and Fermi satellites, which cover an energy range of 5 orders of magnitude (10(exp -3) keV to 100 keV). We determine a photometric redshift of z = 3.1 +/- 0.1 with a line-of-sight with little or no extinction (AV approx. 0 mag) utilising the optical/NIR SED. From the afterglow, we determine a bulk Lorentz factor of Gamma(sub 0) approx. 250 and an emission radius of R < 1018 cm. The prompt-emission broadband spectral energy distribution is well fit with a broken power law with beta1 = -0.3 +/- 0.1 and beta2 = 0.6 +/- 0.1 that has a break at E = 6.6 +/- 0.9 keV, which can be interpreted as the maximum injection frequency. Self-absorption by the electron population below energies of Ea < 6 keV suggest a magnetic field strength of B approx. 10(exp 5) G. However, all the best fit models underpredict the flux observed in the NIR wavelengths, which also only rebrightens by a factor of approx. 2 during the second prompt emission episode, in stark contrast to the X-ray emission, which rebrightens by a factor of approx. 100. This suggests an afterglow component is dominating the emission. We present GRB 121217A, one of the few GRBs that has multi-wavelength observations of the prompt-emission period and shows that it can

  11. NuSTAR OBSERVATIONS OF GRB 130427A ESTABLISH A SINGLE COMPONENT SYNCHROTRON AFTERGLOW ORIGIN FOR THE LATE OPTICAL TO MULTI-GEV EMISSION

    SciTech Connect

    Kouveliotou, C.; Racusin, J. L.; Gehrels, N.; McEnery, J. E.; Zhang, W. W.; Bellm, E.; Harrison, F. A.; Vianello, G.; Oates, S.; Fryer, C. L.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Dermer, C. D.; Hailey, C. J.; Melandri, A.; Tagliaferri, G.; Mundell, C. G.; Stern, D. K. E-mail: granot@openu.ac.il

    2013-12-10

    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. Such an origin of the late-time Fermi/Large Area Telescope >10 GeV photons requires revisions in our understanding of collisionless relativistic shock physics.

  12. The puzzling afterglow of GRB 050721: a rebrightening seen in the optical but not in the X-ray.

    PubMed

    Antonelli, L Angelo; Testa, Vincenzo; Romano, Patrizia; Guetta, Dafne; Torii, Ken'ichi; D'Elia, Valerio; Malesani, Daniele

    2007-05-15

    We present here the analysis of the early and late multiwavelength afterglow emission, as observed by Swift a small robotic telescope and very large telescope (VLT). We compare early observations with late afterglow observations obtained with Swift and the VLT and we observe an intense rebrightening in the optical band at about 1 day after the burst, which is not present in the X-ray band. The lack of detection in X-ray of such a strong rebrightening at lower energies may be described with a variable external density profile. In such a scenario, the combined X-ray and optical observations allow us to derive that the matter density located at approximately 1017 cm from the burst is approximately a factor of 10 higher than in the inner region. This is the first time in which a rebrightening has been observed in the optical afterglow of a gamma-ray burst that is clearly absent in the X-ray afterglow. PMID:17293339

  13. THERMAL EMISSION IN THE EARLY X-RAY AFTERGLOWS OF GAMMA-RAY BURSTS: FOLLOWING THE PROMPT PHASE TO LATE TIMES

    SciTech Connect

    Friis, Mette; Watson, Darach E-mail: darach@dark-cosmology.dk

    2013-07-01

    Thermal radiation, peaking in soft X-rays, has now been detected in a handful of gamma-ray burst (GRB) afterglows and has to date been interpreted as shock break-out of the GRB's progenitor star. We present a search for thermal emission in the early X-ray afterglows of a sample of Swift bursts selected by their brightness in X-rays at early times. We identify a clear thermal component in eight GRBs and track the evolution. We show that at least some of the emission must come from highly relativistic material since two show an apparent super-luminal expansion of the thermal component. Furthermore, we determine very large luminosities and high temperatures for many of the components-too high to originate in a supernova shock break-out. Instead, we suggest that the component may be modeled as late photospheric emission from the jet, linking it to the apparently thermal component observed in the prompt emission of some GRBs at gamma-ray and hard X-ray energies. By comparing the parameters from the prompt emission and the early afterglow emission, we find that the results are compatible with the interpretation that we are observing the prompt quasi-thermal emission component in soft X-rays at a later point in its evolution.

  14. a Three-Stage Model for the Inner Engine of GRBs:. Prompt Emission and Early Afterglow

    NASA Astrophysics Data System (ADS)

    Staff, J.; Niebergal, B.; Ouyed, R.

    We describe a model within the "quark-nova" scenario to interpret the recent observations of early X-ray afterglows of long gamma-ray bursts (GRBs) with the Swift satellite. This is a three-stage model within the context of a core-collapse supernova. STAGE 1 is an accreting (proto-) neutron star leading to a possible delay between the core collapse and the GRB. STAGE 2 is accretion onto a quark star, launching an ultrarelativistic jet generating the prompt GRB. This jet also creates the afterglow as the jet interacts with the surrounding medium creating an external shock. Slower shells ejected from the quark star (during accretion), can re-energize the external shock leading to a flatter segment in the X-ray afterglow. STAGE 3, which occurs only if the quark star collapses to form a black hole, consists of an accreting black hole. The jet launched in this accretion process interacts with the preceding quark star jet, and could generate the flaring activity frequently seen in early X-ray afterglows. Alternatively, a STAGE 2b can occur in our model if the quark star does not collapse to a black hole. The quark star in this case can then spin down due to magnetic braking, and the spin down energy may lead to flattening in the X-ray afterglow as well. This model seems to account for both the energies and the timescales of GRBs, in addition to the newly discovered early X-ray afterglow features.

  15. VizieR Online Data Catalog: 8 Fermi GRB afterglows follow-up (Singer+, 2015)

    NASA Astrophysics Data System (ADS)

    Singer, L. P.; Kasliwal, M. M.; Cenko, S. B.; Perley, D. A.; Anderson, G. E.; Anupama, G. C.; Arcavi, I.; Bhalerao, V.; Bue, B. D.; Cao, Y.; Connaughton, V.; Corsi, A.; Cucchiara, A.; Fender, R. P.; Fox, D. B.; Gehrels, N.; Goldstein, A.; Gorosabel, J.; Horesh, A.; Hurley, K.; Johansson, J.; Kann, D. A.; Kouveliotou, C.; Huang, K.; Kulkarni, S. R.; Masci, F.; Nugent, P.; Rau, A.; Rebbapragada, U. D.; Staley, T. D.; Svinkin, D.; Thone, C. C.; de Ugarte Postigo, A.; Urata, Y.; Weinstein, A.

    2015-10-01

    In this work, we present the GBM-iPTF (intermediate Palomar Transient Factory) afterglows from the first 13 months of this project. Follow-up observations include R-band photometry from the P48, multicolor photometry from the P60, spectroscopy (acquired with the P200, Keck, Gemini, APO, Magellan, Very Large Telescope (VLT), and GTC), and radio observations with the Very Large Array (VLA), the Combined Array for Research in Millimeter-wave Astronomy (CARMA), the Australia Telescope Compact Array (ATCA), and the Arcminute Microkelvin Imager (AMI). (3 data files).

  16. A Correlated Optical and Gamma Emission from GRB 081126A

    SciTech Connect

    Gendre, B.; Klotz, A.; Atteia, J. L.; Boeer, M.; Coward, D. M.; Imerito, A. C.

    2010-10-15

    We present an analysis of time-resolved optical emissions observed from the gamma-ray burst GRB 081126 during the prompt phase. The analysis employed time-resolved photometry using optical data obtained by the TAROT telescope, BAT data from the Swift spacecraft and time-resolved spectroscopy at high energies from the GBM instrument onboard the Fermi spacecraft. The optical emission of GRB 081126 is found to be compatible with the second gamma emission pulse shifted by a positive time-lag of 8.4{+-}3.9 sec. This is the first well resolved observation of a time lag between optical and gamma emissions during a gamma-ray burst. Our observations could potentially provide new constraints on the fireball model for gamma ray burst early emissions. Furthermore, observations of time-lags between optical and gamma ray photons provides an exciting opportunity to constrain quantum gravity theories.

  17. Decay of the GRB 990123 optical afterglow: implications for the fireball model

    PubMed

    Castro-Tirado; Zapatero-Osorio; Caon; Cairos; Hjorth; Pedersen; Andersen; Gorosabel; Bartolini; Guarnieri; Piccioni; Frontera; Masetti; Palazzi; Pian; Greiner; Hudec; Sagar; Pandey; Mohan; Yadav; Nilakshi; Bjornsson; Jakobsson; Burud; et

    1999-03-26

    Broad-band (ultraviolet to near-infrared) observations of the intense gamma ray burst GRB 990123 started approximately 8.5 hours after the event and continued until 18 February 1999. When combined with other data, in particular from the Robotic Telescope and Transient Source Experiment (ROTSE) and the Hubble Space Telescope (HST), evidence emerges for a smoothly declining light curve, suggesting some color dependence that could be related to a cooling break passing the ultraviolet-optical band at about 1 day after the high-energy event. The steeper decline rate seen after 1.5 to 2 days may be evidence for a collimated jet pointing toward the observer. PMID:10092226

  18. Effect of secondary emission on the argon plasma afterglow with large dust density

    SciTech Connect

    Denysenko, I. B.; Azarenkov, N. A.; Burmaka, G. P.; Stefanović, I.

    2015-02-15

    A zero-dimensional, space-averaged model for argon plasma afterglow with large dust density is developed. In the model, three groups of electrons in the plasma afterglow are assumed: (i) thermal electrons with Maxwellian distribution, (ii) energetic electrons generated by metastable-metastable collisions (metastable pooling), and (iii) secondary electrons generated at collisions of ions with the electrodes, which have sufficiently large negative voltages in the afterglow. The model calculates the time-dependencies for electron densities in plasma afterglow based on experimental decay times for metastable density and electrode bias. The effect of secondary emission on electron density in the afterglow is estimated by varying secondary emission yields. It is found that this effect is less important than metastable pooling. The case of dust-free plasma afterglow is considered also, and it is found that in the afterglow the effect of secondary emission may be more important than metastable pooling. The secondary emission may increase thermal electron density n{sub e} in dust-free and dusty plasma afterglows on a few ten percentages. The calculated time dependencies for n{sub e} in dust-free and dusty plasma afterglows describe well the experimental results.

  19. Search for TeV Gamma-ray Emission from GRB 100621A, an extremely bright GRB in X-rays, with H.E.S.S.

    NASA Astrophysics Data System (ADS)

    H.E.S.S. Collaboration; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Angüner, E.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Bernlöhr, K.; Birsin, E.; Bissaldi, E.; Biteau, J.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Chalme-Calvet, R.; Chaves, R. C. G.; Cheesebrough, A.; Chrétien, M.; Colafrancesco, S.; Cologna, G.; Conrad, J.; Couturier, C.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Edwards, T.; Egberts, K.; Eger, P.; Espigat, P.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giebels, B.; Glicenstein, J. F.; Grondin, M.-H.; Grudzińska, M.; Häffner, S.; Hahn, J.; Harris, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Janiak, M.; Jankowsky, F.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Kieffer, M.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Krayzel, F.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lefaucheur, J.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Méhault, J.; Menzler, U.; Meyer, M.; Moderski, R.; Mohamed, M.; Moulin, E.; Murach, T.; Naumann, C. L.; de Naurois, M.; Niemiec, J.; Nolan, S. J.; Oakes, L.; O'Brien, P. T.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, R. D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Poon, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Rob, L.; Romoli, C.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sol, H.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tam, P. H. T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tluczykont, M.; Trichard, C.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorster, M.; Wagner, S. J.; Wagner, P.; Ward, M.; Weidinger, M.; Weitzel, Q.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    2014-05-01

    The long gamma-ray burst (GRB) 100621A, at the time the brightest X-ray transient ever detected by Swift-XRT in the 0.3-10 keV range, has been observed with the H.E.S.S. imaging air Cherenkov telescope array, sensitive to gamma radiation in the very-high-energy (VHE, >100 GeV) regime. Due to its relatively small redshift of z ~ 0.5, the favourable position in the southern sky and the relatively short follow-up time (<700 s after the satellite trigger) of the H.E.S.S. observations, this GRB could be within the sensitivity reach of the H.E.S.S. instrument. The analysis of the H.E.S.S. data shows no indication of emission and yields an integral flux upper limit above ~380 GeV of 4.2 × 10-12 cm-2 s-1 (95% confidence level), assuming a simple Band function extension model. A comparison to a spectral-temporal model, normalised to the prompt flux at sub-MeV energies, constraints the existence of a temporally extended and strong additional hard power law, as has been observed in the other bright X-ray GRB 130427A. A comparison between the H.E.S.S. upper limit and the contemporaneous energy output in X-rays constrains the ratio between the X-ray and VHE gamma-ray fluxes to be greater than 0.4. This value is an important quantity for modelling the afterglow and can constrain leptonic emission scenarios, where leptons are responsible for the X-ray emission and might produce VHE gamma rays.

  20. A Bulk Comptonization Model for the Prompt GRB Emission and its Relation to the Fermi GRB Spectra

    NASA Technical Reports Server (NTRS)

    Kazanas, Demosthenes

    2010-01-01

    We present a model in which the GRB prompt emission at E E(sub peak) is due to bulk Comptonization by the relativistic blast wave motion of either its own synchrotron photons of ambient photons of the stellar configuration that gave birth to the GRB. The bulk Comptonization process then induces the production of relativistic electrons of Lorentz factor equal to that of the blast wave through interactions with its ambient protons. The inverse compton emission of these electrons produces a power law component that extends to multi GeV energies in good agreement with the LAT GRB observations.

  1. GRB 081007 AND GRB 090424: THE SURROUNDING MEDIUM, OUTFLOWS, AND SUPERNOVAE

    SciTech Connect

    Jin Zhiping; Covino, Stefano; Fugazza, Dino; Melandri, Andrea; Campana, Sergio; D'Avanzo, Paolo; Della Valle, Massimo; Ferrero, Patrizia; Malesani, Daniele; Fynbo, Johan P. U.; Hjorth, Jens; Pian, Elena; Salvaterra, Ruben; Bersier, David; Cano, Zach; Castro-Tirado, Alberto J.; Gorosabel, Javier; Guidorzi, Cristiano; Haislip, Joshua B.; and others

    2013-09-10

    We discuss the results of the analysis of multi-wavelength data for the afterglows of GRB 081007 and GRB 090424, two bursts detected by Swift. One of them, GRB 081007, also shows a spectroscopically confirmed supernova, SN 2008hw, which resembles SN 1998bw in its absorption features, while the maximum magnitude may be fainter, up to 0.7 mag, than observed in SN 1998bw. Bright optical flashes have been detected in both events, which allows us to derive solid constraints on the circumburst-matter density profile. This is particularly interesting in the case of GRB 081007, whose afterglow is found to be propagating into a constant-density medium, yielding yet another example of a gamma-ray burst (GRB) clearly associated with a massive-star progenitor which did not sculpt the surroundings with its stellar wind. There is no supernova component detected in the afterglow of GRB 090424, likely due to the brightness of the host galaxy, comparable to the Milky Way. We show that the afterglow data are consistent with the presence of both forward- and reverse-shock emission powered by relativistic outflows expanding into the interstellar medium. The absence of optical peaks due to the forward shock strongly suggests that the reverse-shock regions should be mildly magnetized. The initial Lorentz factor of outflow of GRB 081007 is estimated to be {Gamma} {approx} 200, while for GRB 090424 a lower limit of {Gamma} > 170 is derived. We also discuss the prompt emission of GRB 081007, which consists of just a single pulse. We argue that neither the external forward-shock model nor the shock-breakout model can account for the prompt emission data and suggest that the single-pulse-like prompt emission may be due to magnetic energy dissipation of a Poynting-flux-dominated outflow or to a dissipative photosphere.

  2. MITSuME: multicolor optical/NIR telescopes for GRB afterglows

    SciTech Connect

    Shimokawabe, Takashi; Kawai, Nobuyuki; Kotani, Taro; Yatsu, Yoichi; Ishimura, Takuto; Vasquez, Nicolas; Mori, Yuki; Kudo, Yusuke; Yoshida, Michitoshi; Yanagisawa, Kenshi; Nagayama, Shogo; Toda, Hiroyuki; Shimozu, Yasuhiro; Kuroda, Daisuke; Watanabe, Junichi; Fukushima, Hideo; Mori, Masaki

    2008-05-22

    Multicolor Imaging Telescopes for Survey and Monstrous Explosions (MITSuME) is built to perform multi-color photometry of NIR/optical afterglow covering the wavebands from K{sub s} to g' allowing the photometric redshift measurements up to z{approx_equal}10.Two 50 cm optical telescopes are built at Akeno, Yamanashi in eastern Japan, and at OAO, Okayama in western Japan. Each telescope has a Tricolor Camera, which allows us to take simultaneous images in g', R{sub c} and I{sub c} bands. These telescopes respond to GCN alerts and start taking series of tricolor images, which are immediately processed through the analys is pipeline on site. The pipeline consists of source finding, catalog matching, sky coordinates mapping to the image pixels, and photometry of the found sources. In addition, an automated search for an optical counterpart is performed.In addition, a wide-field (1 deg.) 91 cm NIR telescope is being built at OAO with filters in K{sub s}, H, J, and y bands.Summary of early results will be also presented.

  3. Detection of High-energy Gamma-Ray Emission During the X-Ray Flaring Activity in GRB 100728A

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Ajello, 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.; Bonnell, J.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Connaughton, V.; Conrad, J.; Cutini, S.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Granot, J.; Grenier, I. A.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kerr, M.; Knödlseder, J.; Kuss, M.; Lande, J.; Latronico, L.; Lee, S.-H.; Longo, F.; Loparco, F.; Lott, B.; Lubrano, P.; Mazziotta, M. N.; McEnery, J. E.; Mészáros, P.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monzani, M. E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakamori, T.; Naumann-Godo, M.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohsugi, T.; Okumura, A.; Omodei, N.; Orlando, E.; Paciesas, W. S.; Pelassa, V.; Pesce-Rollins, M.; Pierbattista, M.; Piron, F.; Porter, T. A.; Racusin, J. L.; Rainò, S.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reyes, L. C.; Roth, M.; Sadrozinski, H. F.-W.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Sonbas, E.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Strickman, M. S.; Takahashi, H.; Tanaka, T.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Torres, D. F.; Tosti, G.; Troja, E.; Uehara, T.; Usher, T. L.; Vandenbroucke, J.; Vasileiou, V.; Vianello, G.; Vilchez, N.; Vitale, V.; von Kienlin, A.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Yamazaki, R.; Yang, Z.; Ziegler, M.; Piro, L.

    2011-06-01

    We present the simultaneous Swift and Fermi observations of the bright GRB 100728A and its afterglow. The early X-ray emission is dominated by a vigorous flaring activity continuing until 1 ks after the burst. In the same time interval, high-energy emission is significantly detected by the Fermi/Large Area Telescope. Marginal evidence of GeV emission is observed up to later times. We discuss the broadband properties of this burst within both the internal and external shock scenarios, with a particular emphasis on the relation between X-ray flares, the GeV emission, and a continued long-duration central engine activity as their power source.

  4. The Optical Afterglow of a Short Gamma-ray Burst

    NASA Technical Reports Server (NTRS)

    Hjorth, Jens; Watson, Darach; Flynbo, Johan P.U.; Price, Paul A.; Jensen, Brian L.; Jorgensen, Uffe G.; Kubas, Daniel; Gorosabel, Javier; Jakobssonk, Pall; Sollerman, Jesper

    2005-01-01

    It has long been known that there are two classes of gamma-ray bursts (GRBs), principally distinguished by their durations. The breakthrough in our understanding of long-duration GRBs (greater than 2 seconds in duration), that ultimately linked them with energetic Type Ic supernovae, came about from the discovery of their long-lived X-ray and optical "afterglow", when precise and rapid localizations of the sources could finally be obtained. Recently, X-ray localizations have become available for short (less than 2 seconds in duration) GRBs, a hitherto elusive GRB population, that has evaded optical detection for more than thirty years. Here we report the discovery of transient optical emission (R approximately 23 mag) associated with a short GRB. This first short GRB afterglow is localized with sub-arcsecond accuracy onto the outskirts of a blue dwarf galaxy. Unless the optical and X-ray afterglow arise from different mechanisms our observations 33 h after the GRB suggest that, analogously to long GRBs, we observe synchrotron emission from ultrarelativistic ejecta (ZZZ CAN WE LIMIT GAMMA?). In contrast, we did not detect a bright supernova, as found in most nearby long GRB afterglows, which suggests a different origidstrongly constrain the nature of the short GRB progenitors.

  5. DISCOVERY OF RADIO AFTERGLOW FROM THE MOST DISTANT COSMIC EXPLOSION

    SciTech Connect

    Chandra, Poonam; Frail, Dale A.; Fox, Derek; Kulkarni, Shrinivas; Harrsion, Fiona; Kasliwal, Mansi; Berger, Edo; Cenko, S. Bradley; Bock, Douglas C.-J.

    2010-03-20

    We report on the discovery of radio afterglow emission from the gamma-ray burst GRB 090423, which exploded at a redshift of 8.3, making it the object with the highest known redshift in the universe. By combining our radio measurements with existing X-ray and infrared observations, we estimate the kinetic energy of the afterglow, the geometry of the outflow, and the density of the circumburst medium. Our best-fit model suggests a quasi-spherical, high-energy explosion in a low, constant-density medium. GRB 090423 had a similar energy release to the other well-studied high redshift GRB 050904 (z = 6.26), but their circumburst densities differ by 2 orders of magnitude. We compare the properties of GRB 090423 with a sample of gamma-ray bursts (GRBs) at moderate redshifts. We find that the high energy and afterglow properties of GRB 090423 are not sufficiently different from other GRBs to suggest a different kind of progenitor, such as a Population III (Pop III) star. However, we argue that it is not clear that the afterglow properties alone can provide convincing identification of Pop III progenitors. We suggest that the millimeter and centimeter radio detections of GRB 090423 at early times contained emission from the reverse shock. If true, this may have important implications for the detection of high-redshift GRBs by the next generation of radio facilities.

  6. 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.; Gehrels, N.; Marshall, F. E.; Mawson, N.; Melandri,; 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.

    2012-01-01

    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(sub gamma),<3x10(exp 49) 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. Subject headings: gamma-ray bursts: individual (GRB 091127)

  7. Prompt and Afterglow Emission Properties of Gamma-Ray Bursts with Spectroscopically Identified Supernovae

    NASA Technical Reports Server (NTRS)

    Kaneko, Yuki; Ramirez-Ruiz, Enrico; Granot, Jonathan; Kouveliotou, Chryssa; Woosley, Stan E.; Patel, Sandeep K.; Rol, Evert; In'TZand, Jean J. M.; VanDerHorst, Alexander J.; Wuers, Ralph A. M. J.; Strom, Richard

    2007-01-01

    We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425,030329,031203, and 060218) that were spectroscopically found to be associated with Type Ic supernovae and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolution and estimate the total energy budget based on broadband observations. The observational inventory for these events has become rich enough to allow estimates of their energy content in relativistic and subrelativistic form. The result is a global portrait of the effects of the physical processes responsible for producing long-soft GRBs. In particular, we find that the values of the energy released in mildly relativistic outflows appears to have a significantly smaller scatter than those found in highly relativistic ejecta. This is consistent with a picture in which the energy released inside the progenitor star is roughly standard, while the fraction of that energy that ends up in highly relativistic ejecta outside the star can vary dramatically between different events.

  8. Prompt and Afterglow Emission Properties of Gamma-Ray Bursts with Spectroscopically Identified Supernovae

    SciTech Connect

    Kaneko, Yuki; Ramirez-Ruiz, E.; Granot, J.; Kouveliotou, C.; Woosley, S.E.; Patel, S.K.; Rol, E.; Zand, J.J.M.in't; a; Wijers, R.A.M.J.; Strom, R.; /USRA, Huntsville /Princeton, Inst. Advanced Study /UC, Santa Cruz /KIPAC, Menlo Park /NASA, Marshall /Leicester U. /SRON, Utrecht /Utrecht, Astron. Inst. /Amsterdam U., Astron. Inst. /NFRA, Dwingeloo

    2006-07-12

    We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425, 030329, 031203, and 060218) that were spectroscopically found to be associated with type Ic supernovae, and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolution, and estimate the total energy budget based upon broadband observations. The observational inventory for these events has become rich enough to allow estimates of their energy content in relativistic and sub-relativistic form. The result is a global portrait of the effects of the physical processes responsible for producing long-soft GRBs. In particular, we find that the values of the energy released in mildly relativistic outflows appears to have a significantly smaller scatter than those found in highly relativistic ejecta. This is consistent with a picture in which the energy released inside the progenitor star is roughly standard, while the fraction of that energy that ends up in highly relativistic ejecta outside the star can vary dramatically between different events.

  9. GRB 050826: A Subluminous Event at z=0.296 Finds Its Place in the Luminosity Distribution of Gamma-Ray Burst Afterglows

    NASA Technical Reports Server (NTRS)

    Mirabal, N.; Halpern J. P.; O'Brien, P. T.

    2007-01-01

    We present the optical identification and spectroscopy of the host galaxy of GRB 050826 at redshift z = 0.296 +/- 0.001. Image subtraction among observations obtained on three consecutive nights reveals a fading object 5 hr after the burst, confirming its identification as the optical afterglow of this event. Deep imaging shows that the optical afterglow is offset by 0.4" (1.76 kpc) from the center of its irregular host galaxy, which is typical for long-duration gamma-ray bursts. Combining these results with X-ray measurements acquired by the Swift XRT instrument, we find that GRB 050826 falls entirely within the subluminous, subenergetic group of long gamma-ray bursts at low redshift (z less than or equal to 0.3). The results are discussed in the context of models that possibly account for this trend, including the nature of the central engine, the evolution of progenitor properties as a function of redshift, and incompleteness in current gamma-ray burst samples.

  10. The extinction curves of star-forming regions from z = 0.1 to 6.7 using GRB afterglow spectroscopy

    NASA Astrophysics Data System (ADS)

    Zafar, T.; Watson, D.; Fynbo, J. P. U.; Malesani, D.; Jakobsson, P.; de Ugarte Postigo, A.

    2011-08-01

    Studies of extinction curves provide insights into the properties of interstellar dust. Until recently, however, very few extinction curves existed outside the local group. GRB afterglows are well suited to extinction studies due to their brightness, simple power-law spectra and their occurrence in distant star forming galaxies. In this paper we present results from the SED analysis of a sample of 41 GRB afterglows, from X-ray to NIR wavelengths. The sample is based on spectra from VLT-FORS, with additional data primarily from Swift. This is the largest sample of extinction curves outside the Local Group and, to date, the only extragalactic sample of absolute extinction curves based on spectroscopy. Estimates of the distribution of restframe visual extinctions, the extinction curves, and the intrinsic spectral shapes of GRB afterglows are obtained. Their correlation with H i column density as well as total and gas-phase metal column density are examined. The line-of-sight gas-to-dust and metals-to-dust ratios are determined and examined as a function of total column density, ISM metallicity and redshift. The intrinsic SEDs of the afterglows show that approximately half the sample require a cooling break between the optical and X-ray ranges. The broken power-law SEDs show an average change in the spectral index of Δβ = 0.51 with a very small standard deviation of 0.02 (excluding the outlier GRB 080210). This is consistent with the expectations from a simple synchrotron model. Such a close convergence of values suggests that the X-ray afterglows of GRBs may be used with considerably more confidence to set the absolute flux level and intrinsic spectral indices in the optical and UV. Of the sample, 63% are well described by a featureless (SMC-type) extinction curve. Almost a quarter of our sample is consistent with no significant extinction (typically AV ≲ 0.1). The 2175 Å extinction bump is detected unequivocally in 7% of our sample (3 GRBs), which all have AV

  11. GRB 070724B: the first Gamma Ray Burst localized by SuperAGILE

    SciTech Connect

    Del Monte, E.; Costa, E.; Donnarumma, I.; Feroci, M.; Lapshov, I.; Lazzarotto, F.; Soffitta, P.; Argan, A.; Pucella, G.; Trois, A.; Vittorini, V.; Evangelista, Y.; Rapisarda, M.; Barbiellini, G.; Longo, F.; Basset, M.; Foggetta, L.; Vallazza, E.; Bulgarelli, A.; Di Cocco, G.

    2008-05-22

    GRB070724B is the first Gamma Ray Burst localized by the SuperAGILE instrument aboard the AGILE space mission. The SuperAGILE localization has been confirmed after the after-glow observation by the XRT aboard the Swift satellite. No significant gamma ray emission above 50 MeV has been detected for this GRB. In this paper we describe the SuperAGILE capabilities in detecting Gamma Ray Burst and the AGILE observation of GRB 070724B.

  12. Prospects for detection of very high-energy emission from GRB in the context of the external shock model

    NASA Astrophysics Data System (ADS)

    Galli, A.; Piro, L.

    2008-10-01

    Context: The detection of the 100 GeV-TeV emission by a gamma-ray burst (GRB) will provide an unprecedented opportunity to study the nature of the central engine and the interaction between the relativistic flow and the environment of the burst's progenitor. Aims: In this paper we show that there are exciting prospects of detecting from the burst by MAGIC high-energy (HE) emission during the early X-ray flaring activity and, later, during the normal afterglow phase. We also identify the best observational strategy: trigger conditions and time period of observation. Methods: We determine the expected HE emission from the flaring and afterglow phases of GRBs in the context of the external shock scenario and compare them with the MAGIC threshold. Results: We find that an X-ray flare with the average properties of the class can be detected in the 100 GeV range by MAGIC, provided that z ≲ 0.7. The requested observational window with MAGIC should then start from 10-20 s after the burst and cover about 1000-2000 s. Furthermore, we demonstrate that there are solid prospects of detecting the late afterglow emission in the same energy range for most of the bursts with z ≲ 0.5 if the density of the external medium is n ≳ a few cm-3. In this case, the MAGIC observation shall extend to about 10-20 ks. We provide recipes for tailoring this prediction to the observational properties of each burst, in particular the fluence in the prompt emission and the redshift, thus allowing an almost real time decision procedure to decide whether to continue the follow-up observation of a burst at late times.

  13. New Directions for GRB Prompt Emission Theory

    SciTech Connect

    Preece, Robert D.

    2008-05-22

    A number of recent theory and simulation results by Nordlund, Hededal, Nishikawa, Medvedev, Brainerd and others are improving our understanding of the prompt emission of GRBs. Observations of GBM spectra from various instruments have consistently painted a picture that tends not to support the prevailing hydrodynamic synchrotron shock models. I will attempt to put the observations and the recent results together into a coherent picture that suggests new directions for future investigations by theory, simulations as well as observations, especially by GLAST.

  14. Luminosity Correlations for Gamma-Ray Bursts and Implications for Their Prompt and Afterglow Emission Mechanisms

    NASA Astrophysics Data System (ADS)

    Sultana, J.; Kazanas, D.; Fukumura, K.

    2012-10-01

    We present the relation between the (z- and k-corrected) spectral lags, τ, for the standard Swift energy bands 50-100 keV and 100-200 keV and the peak isotropic luminosity, L iso (a relation reported first by Norris et al.), for a subset of 12 long Swift gamma-ray bursts (GRBs) taken from a recent study of this relation by Ukwatta et al. The chosen GRBs are also a subset of the Dainotti et al. sample, a set of Swift GRBs of known redshift, employed in establishing a relation between the (GRB frame) luminosity, LX , of the shallow (or constant) flux portion of the typical X-Ray Telescope GRB-afterglow light curve and the (GRB frame) time of transition to the normal decay rate, T brk. We also present the LX -T brk relation using only the bursts common in the two samples. The two relations exhibit a significant degree of correlation (ρ = -0.65 for the L iso-τ and ρ = -0.88 for the LX -T brk relation) and have surprisingly similar best-fit power-law indices (-1.19 ± 0.17 for L iso-τ and -1.10 ± 0.03 for LX -T brk). Even more surprisingly, we noted that although τ and T brk represent different GRB time variables, it appears that the first relation (L iso-τ) extrapolates into the second one for timescales τ ~= T brk. This fact suggests that these two relations have a common origin, which we conjecture to be kinematic. This relation adds to the recently discovered relations between properties of the prompt and afterglow GRB phases, indicating a much more intimate relation between these two phases than hitherto considered.

  15. Luminosity Correlations for Gamma-Ray Bursts and Implications for Their Prompt and Afterglow Emission Mechanisms

    NASA Technical Reports Server (NTRS)

    Sultana, J.; Kazanas, D.; Fukumura, K

    2013-01-01

    We present the relation between the (z- and k-corrected) spectral lags, tau, for the standard Swift energy bands 50 - 100 keV and 100 - 200 keV and the peak isotropic luminosity, L(sub iso) (a relation reported first by Norris et al.), for a subset of 12 long Swift GRBs taken from a recent study of this relation by Ukwatta et al. The chosen GRBs are also a subset of the Dainotti et al. sample, a set of Swift GRBs of known redshift, employed in establishing a relation between the (GRB frame) luminosity, L(sub x), of the shallow (or constant) flux portion of the typical XRT GRB-afterglow light curve and the (GRB frame) time of transition to the normal decay rate, T(sub brk). We also present the L(sub x) - T(sub brk) relation using only the bursts common in the two samples. The two relations exhibit a significant degree of correlation (rho = -0.65 for the L(sub iso) - tao and rho = -0.88 for the L(sub x) -T(sub brk) relation) and have surprisingly similar best-fit power law indices (-1.19 +/- 0.17 for L(sub iso) - tau and -1.10 +/- 0.03 for L(sub x) - T(sub brk)). Even more surprisingly, we noted that although tau and T(sub brk) represent different GRB time variables, it appears that the first relation (L(sub iso) - tao) extrapolates into the second one for timescales tau similar to T(sub brk) This fact suggests that these two relations have a common origin, which we conjecture to be kinematic. This relation adds to the recently discovered relations between properties of the prompt and afterglow GRB phases, indicating a much more intimate relation between these two phases than hitherto considered.

  16. GRB 120711A: an intense INTEGRAL burst with long-lasting soft γ-ray emission and a powerful optical flash

    NASA Astrophysics Data System (ADS)

    Martin-Carrillo, A.; Hanlon, L.; Topinka, M.; LaCluyzé, A. P.; Savchenko, V.; Kann, D. A.; Trotter, A. S.; Covino, S.; Krühler, T.; Greiner, J.; McGlynn, S.; Murphy, D.; Tisdall, P.; Meehan, S.; Wade, C.; McBreen, B.; Reichart, D. E.; Fugazza, D.; Haislip, J. B.; Rossi, A.; Schady, P.; Elliott, J.; Klose, S.

    2014-07-01

    A long and intense γ-ray burst (GRB) was detected by INTEGRAL on 11 July 2012 with a duration of ~115 s and fluence of 2.8 × 10-4 erg cm-2 in the 20 keV-8 MeV energy range. GRB 120711A was at z ~ 1.405 and produced soft γ-ray emission (>20 keV) for at least ~10 ks after the trigger. The GRB was observed by several ground-based telescopes that detected a powerful optical flash peaking at an R-band brightness of ~11.5 mag at ~126 s after the trigger, or ~9th magnitude when corrected for the host galaxy extinction (AV ~ 0.85). The X-ray afterglow was monitored by the Swift, XMM-Newton, and Chandra observatories from 8 ks to 7 Ms and provides evidence for a jet break at ~0.9 Ms. We present a comprehensive temporal and spectral analysis of the long-lasting soft γ-ray emission detected in the 20-200 keV band with INTEGRAL/IBIS, the Fermi/LAT post-GRB detection above 100 MeV, the soft X-ray afterglow and the optical/near-infrared detections from Watcher, Skynet/PROMPT, GROND, and REM. The prompt emission had a very hard spectrum (Epeak ~ 1 MeV) and yields an Eγ,iso ~ 1054 erg (1 keV-10 MeV rest frame), making GRB 120711A one of the most energetic GRBs detected so far. We modelled the long-lasting soft γ-ray emission using the standard afterglow scenario, which indicates a forward shock origin. The combination of data extending from the near-infrared to GeV energies suggest that the emission is produced by a broken power-law spectrum consistent with synchrotron radiation. The afterglow is well modelled using a stratified wind-like environment with a density profile k ~ 1.2, suggesting a massive star progenitor (i.e. Wolf-Rayet) with a mass-loss rate between ~10-5-10-6 M⊙ yr-1 depending on the value of the radiative efficiency (ηγ = 0.2 or 0.5). The analysis of the reverse and forward shock emission reveals an initial Lorentz factor of ~120-340, a jet half-opening angle of ~2°-5°, and a baryon load of ~10-5 - 10-6 M⊙ consistent with the expectations of the

  17. BROADBAND STUDY OF GRB 091127: A SUB-ENERGETIC BURST AT HIGHER REDSHIFT?

    SciTech Connect

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

    2012-12-10

    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{sub {gamma}} < 3 Multiplication-Sign 10{sup 49} 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.

  18. Exploring the behaviour of long gamma-ray bursts with intrinsic afterglow correlations

    NASA Astrophysics Data System (ADS)

    Oates, Samantha

    2016-07-01

    We present a correlation observed in both the optical and X-ray afterglows of long duration Gamma-ray Bursts (GRBs), between the initial luminosity (measured at restframe 200s) and average afterglow decay rate. This correlation does not depend on the presence of specific light curve features and is potentially applicable to all long GRB afterglows. We explore how the correlation parameters from the optical and X-ray bands relate to each other and to the prompt emission phase. We will also explore the implications and test if the observations are consistent with the expectations of the standard afterglow model.

  19. Ten per cent polarized optical emission from GRB090102

    NASA Astrophysics Data System (ADS)

    Steele, I. A.; Mundell, C. G.; Smith, R. J.; Kobayashi, S.; Guidorzi, C.

    2009-12-01

    The nature of the jets and the role of magnetic fields in gamma-ray bursts (GRBs) remains unclear. In a baryon-dominated jet only weak, tangled fields generated in situ through shocks would be present. In an alternative model, jets are threaded with large-scale magnetic fields that originate at the central engine and that accelerate and collimate the material. To distinguish between the models the degree of polarization in early-time emission must be measured; however, previous claims of gamma-ray polarization have been controversial. Here we report that the early optical emission from GRB090102 was polarized at 10+/-1 per cent, indicating the presence of large-scale fields originating in the expanding fireball. If the degree of polarization and its position angle were variable on timescales shorter than our 60-second exposure, then the peak polarization may have been larger than ten per cent.

  20. Ten per cent polarized optical emission from GRB 090102.

    PubMed

    Steele, I A; Mundell, C G; Smith, R J; Kobayashi, S; Guidorzi, C

    2009-12-10

    The nature of the jets and the role of magnetic fields in gamma-ray bursts (GRBs) remains unclear. In a baryon-dominated jet only weak, tangled fields generated in situ through shocks would be present. In an alternative model, jets are threaded with large-scale magnetic fields that originate at the central engine and that accelerate and collimate the material. To distinguish between the models the degree of polarization in early-time emission must be measured; however, previous claims of gamma-ray polarization have been controversial. Here we report that the early optical emission from GRB 090102 was polarized at 10 +/- 1 per cent, indicating the presence of large-scale fields originating in the expanding fireball. If the degree of polarization and its position angle were variable on timescales shorter than our 60-second exposure, then the peak polarization may have been larger than ten per cent. PMID:20010682

  1. 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.; Gehrels, Cornelis

    2013-01-01

    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 gamma-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.

  2. 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

    2014-01-01

    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. PMID:24263133

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

    NASA Astrophysics Data System (ADS)

    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.

    2014-01-01

    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.

  4. IN SEARCH OF PROGENITORS FOR SUPERNOVALESS GAMMA-RAY BURSTS 060505 AND 060614: RE-EXAMINATION OF THEIR AFTERGLOWS

    SciTech Connect

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

    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 {gamma}-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.

  5. GABI: a compact detector for GRB prompt emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Natalucci, L.; Ubertini, P.; Bazzano, A.; Federici, M.; Fiocchi, M. T.; Lotti, S.; Grindlay, J. E.; Gehrels, N.; Uslenghi, M.; Fiorini, M.; Perotti, F.

    Triggering on sky transient events can be efficiently accomplished by coded mask instruments, which can also provide positions with arcmin or sub-arcmin accuracy, but at the expense of weight and power. On the other hand good broadband spectroscopy is possible using much lighter systems, that could also provide a coarse positioning capability (˜ degrees). We present the concept of a compact, light detector based on NaI(Tl) scintillator, that can be used to complement other soft X-ray or IR/optical telescopes in detecting transients and characterizing them. The Gamma-Ray Burst Imager (GABI) will operate in the energy range 8-1000 keV that is optimal for the detection of the prompt emission of Gamma-Ray Bursts (GRB). GABI is being proposed for accomodation on board Lobster, a candidate mission of the NASA Explorer Program.

  6. Modeling the Early Multiwavelength Emission in GRB130427A

    NASA Astrophysics Data System (ADS)

    Fraija, N.; Lee, W.; Veres, P.

    2016-02-01

    One of the most powerful gamma-ray bursts, GRB 130427A was swiftly detected from GeV γ-rays to optical wavelengths. In the GeV band, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope observed the highest-energy photon ever recorded of 95 GeV and a bright peak in the early phase followed by emission temporally extended for more than 20 hr. In the optical band, a bright flash with a magnitude of 7.03 ± 0.03 in the time interval from 9.31 to 19.31 s after the trigger was reported by RAPTOR in r band. We study the origin of the GeV γ-ray emission, using the multiwavelength observation detected in X-ray and optical bands. The origin of the temporally extended LAT, X-ray, and optical flux is naturally interpreted as synchrotron radiation, and the 95 GeV photon and the integral flux upper limits placed by the high-altitude water Cerenkov observatory are consistent with synchrotron self-Compton from an adiabatic forward shock propagating into the stellar wind of its progenitor. The extreme LAT peak and the bright optical flash are explained through synchrotron self-Compton and synchrotron emission from the reverse shock, respectively, when the ejecta evolves in the thick-shell regime and carries a significant magnetic field.

  7. GRB 130427A: A Nearby Ordinary Monster

    NASA Astrophysics Data System (ADS)

    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.; Weigand, B.; Wiersema, K.; Yatsu, Y.; Yoshii, T.; Tagliaferri, G.

    2014-01-01

    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 × 1053 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.

  8. 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.; Ghirlander, G.; Ghisellini, G.; Guidorzi, C.; Kobayashi, S.; Kuin, P.; La Parola, V.; Mangano, V.; Oates, S.; Barthelmy, S.; Gehrels, N.; Marshall, F.; Wiegand, B.

    2014-01-01

    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 approx. 3 x 10(exp 53) ergs/s and its relative proximity (z = 0.34), GRB 130427A reached the highest fluence observed in the gamma-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.

  9. 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

    2014-01-01

    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. PMID:24263134

  10. Revisiting the Dispersion Measure of Fast Radio Bursts Associated with Gamma-Ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Yu, Yun-Wei

    2014-12-01

    Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the dispersion measure (DM) of the FRBs from the GRB ejecta and the wind blown from the precollapsing NS. On the one hand, sometimes an internal X-ray plateau afterglow could be produced by the NS wind, which indicates that a great number of electron-positron pairs are carried by the wind. If the pair-generation radius satisfies a somewhat rigorous condition, the relativistic and dense wind would contribute a high DM to the associated FRB, which can be comparable to and even exceed the DM contributed by the intergalactic medium. On the other hand, if the wind only carries a Goldreich-Julian particle flux, its DM contribution would become negligible; meanwhile, the internal plateau afterglow would not appear. Alternatively, the FRB should be associated with a GRB afterglow produced by the GRB external shock, i.e., an energy-injection-caused shallow-decay afterglow or a normal single-power-law afterglow if the impulsive energy release of the GRB is high enough. In the latter case, the DM contributed by the high-mass GRB ejecta could be substantially important, in particular, for an environment of main-sequence stellar wind. In summary, a careful assessment on the various DM contributors could be required for the cosmological application of the expected FRB-GRB association. The future DM measurements of GRB-associated FRBs could provide a constraint on the physics of NS winds.

  11. Revisiting the dispersion measure of fast radio bursts associated with gamma-ray burst afterglows

    SciTech Connect

    Yu, Yun-Wei

    2014-12-01

    Some fast radio bursts (FRBs) are expected to be associated with the afterglow emission of gamma-ray bursts (GRBs), while a short-lived, supermassive neutron star (NS) forms during the GRBs. I investigate the possible contributions to the dispersion measure (DM) of the FRBs from the GRB ejecta and the wind blown from the precollapsing NS. On the one hand, sometimes an internal X-ray plateau afterglow could be produced by the NS wind, which indicates that a great number of electron-positron pairs are carried by the wind. If the pair-generation radius satisfies a somewhat rigorous condition, the relativistic and dense wind would contribute a high DM to the associated FRB, which can be comparable to and even exceed the DM contributed by the intergalactic medium. On the other hand, if the wind only carries a Goldreich-Julian particle flux, its DM contribution would become negligible; meanwhile, the internal plateau afterglow would not appear. Alternatively, the FRB should be associated with a GRB afterglow produced by the GRB external shock, i.e., an energy-injection-caused shallow-decay afterglow or a normal single-power-law afterglow if the impulsive energy release of the GRB is high enough. In the latter case, the DM contributed by the high-mass GRB ejecta could be substantially important, in particular, for an environment of main-sequence stellar wind. In summary, a careful assessment on the various DM contributors could be required for the cosmological application of the expected FRB-GRB association. The future DM measurements of GRB-associated FRBs could provide a constraint on the physics of NS winds.

  12. BDRG and shok instruments for study of GRB prompt emission in michaylo lomonosov space mission

    NASA Astrophysics Data System (ADS)

    Amelushkin, A. M.; Bogomolov, V. V.; Galkin, V. I.; Goncharov, B. V.; Gorbovskoy, E. S.; Kornilov, V. G.; Lipunov, V. M.; Panasyuk, M. I.; Petrov, V. L.; Smoot, G. F.; Svertilov, S. I.; Vedenkin, N. N.; Yashin, I. V.

    2013-07-01

    The study of GRB prompt emission (PE) is one of the main goals of the Lomonosov space mission, which is being prepared at Moscow State University. The GRB monitor (BDRG) and the wide-field optical cameras (SHOK) are intended for detection of GRB prompt emission as well as optical counterparts. The BDRG instrument consists of three identical NaI(Tl)/CsI(Tl) (13.0 × 2.0cm ) phoswich detectors, whose axes determine the Cartesian coordinate system. This allows to localize any GRB source on the sky by means of the count rate seen by each detector with an accuracy of ~2 deg. The SHOK instrument consists of two identical wide-field cameras (WFC) directed in such a way that the field of view (FOV) of each WFC overlaps by the corresponding BDRG FOV, which produces a trigger on the WFC in case of a GRB detection. With this setup, the GRB prompt light curve will be obtained in the visible without any delay with respect to gamma-rays, which is crucial for a GRB central engine understanding.

  13. Evidence of Bulk Acceleration of the GRB X-Ray Flare Emission Region

    NASA Astrophysics Data System (ADS)

    Uhm, Z. Lucas; Zhang, Bing

    2016-06-01

    Applying our recently developed generalized version of the high-latitude emission theory to the observations of X-ray flares in gamma-ray bursts (GRBs), here we present clear observational evidence that the X-ray flare emission region is undergoing rapid bulk acceleration as the photons are emitted. We show that both the observed X-ray flare light curves and the photon index evolution curves can be simultaneously reproduced within a simple physical model invoking synchrotron radiation in an accelerating emission region far from the GRB central engine. Such an acceleration process demands an additional energy dissipation source other than kinetic energy, which points toward a significant Poynting flux in the emission region of X-ray flares. As the X-ray flares are believed to share a similar physical mechanism as the GRB prompt emission, our finding here hints that the GRB prompt emission jets may also carry a significant Poynting flux in their emitting region.

  14. VLT/X-Shooter spectroscopy of the afterglow of the Swift GRB 130606A. Chemical abundances and reionisation at z ~ 6

    NASA Astrophysics Data System (ADS)

    Hartoog, O. E.; Malesani, D.; Fynbo, J. P. U.; Goto, T.; Krühler, T.; Vreeswijk, P. M.; De Cia, A.; Xu, D.; Møller, P.; Covino, S.; D'Elia, V.; Flores, H.; Goldoni, P.; Hjorth, J.; Jakobsson, P.; Krogager, J.-K.; Kaper, L.; Ledoux, C.; Levan, A. J.; Milvang-Jensen, B.; Sollerman, J.; Sparre, M.; Tagliaferri, G.; Tanvir, N. R.; de Ugarte Postigo, A.; Vergani, S. D.; Wiersema, K.; Datson, J.; Salinas, R.; Mikkelsen, K.; Aghanim, N.

    2015-08-01

    Context. The reionisation of the Universe is a process that is thought to have ended around z ~ 6, as inferred from spectroscopy of distant bright background sources, such as quasars (QSO) and gamma-ray burst (GRB) afterglows. Furthermore, spectroscopy of a GRB afterglow provides insight in its host galaxy, which is often too dim and distant to study otherwise. Aims: For the Swift GRB 130606A at z = 5.913 we have obtained a high S/N spectrum covering the full optical and near-IR wavelength region at intermediate spectral resolution with VLT/X-Shooter. We aim to measure the degree of ionisation of the intergalactic medium (IGM) between z = 5.02-5.84 and to study the chemical abundance pattern and dust content of its host galaxy. Methods: We estimated the UV continuum of the GRB afterglow using a power-law extrapolation, then measured the flux decrement due to absorption at Lyα,β, and γ wavelength regions. Furthermore, we fitted the shape of the red damping wing of Lyα. The hydrogen and metal absorption lines formed in the host galaxy were fitted with Voigt profiles to obtain column densities. We investigated whether ionisation corrections needed to be applied. Results: Our measurements of the Lyα-forest optical depth are consistent with previous measurements of QSOs, but have a much smaller uncertainty. The analysis of the red damping wing yields a neutral fraction xH i< 0.05 (3σ). We obtain column density measurements of H, Al, Si, and Fe; for C, O, S and Ni we obtain limits. The ionisation due to the GRB is estimated to be negligible (corrections <0.03 dex), but larger corrections may apply due to the pre-existing radiation field (up to 0.4 dex based on sub-DLA studies). Assuming that [ Si/Fe ] = +0.79 ± 0.13 is due to dust depletion, the dust-to-metal ratio is similar to the Galactic value. Conclusions: Our measurements confirm that the Universe is already predominantly ionised over the redshift range probed in this work, but was slightly more neutral at z

  15. The ``Christmas burst'' GRB 101225A revisited

    NASA Astrophysics Data System (ADS)

    Thöne, C. C.; de Ugarte Postigo, A.; Fryer, C. L.; Kann, D. A.

    2015-03-01

    Long GRBs are related to the death of massive stars and reveal themselves through synchrotron emission from highly relativistic jets. The `Christmas Burst' GRB 101225A was an exceptionally long GRB with a thermal afterglow, very different from the standard GRB. Initially, no spectroscopic redshift could be obtained and SED modeling yielded z=0.33. A plausible model was a He-NS star merger where the He-star had ejected part of its envelope in the common envelope phase during inspiral. The interaction between the jet and the previously ejected shell can explains the thermal emission. We obtained deep spectroscopy of the host galaxy which leads to a correction of the redshift to z=0.847. Despite the higher redshift, our model is still valid and theoretically better justified than the alternative suggestion of a blue supergiant progenitor proposed by Levan et al. (2014) for several ``ultra-long'' GRBs.

  16. The potential for detecting gamma-ray burst afterglows from population III stars with the next generation of infrared telescopes

    SciTech Connect

    Macpherson, D.; Coward, D. M.; Zadnik, M. G.

    2013-12-10

    We investigate the detectability of a proposed population of gamma-ray bursts (GRBs) from the collapse of Population III (Pop III) stars. The James Webb Space Telescope (JWST) and Space Infrared Telescope for Cosmology and Astrophysics (SPICA) will be able to observe the late time infrared afterglows. We have developed a new method to calculate their detectability, which takes into account the fundamental initial mass function and formation rates of Pop III stars, from which we find the temporal variability of the afterglows and ultimately the length of time JWST and SPICA can detect them. In the range of plausible Pop III GRB parameters, the afterglows are always detectable by these instruments during the isotropic emission, for a minimum of 55 days and a maximum of 3.7 yr. The average number of detectable afterglows will be 2.96× 10{sup –5} per SPICA field of view (FOV) and 2.78× 10{sup –6} per JWST FOV. These are lower limits, using a pessimistic estimate of Pop III star formation. An optimal observing strategy with SPICA could identify a candidate orphan afterglow in ∼1.3 yr, with a 90% probability of confirmation with further detailed observations. A beamed GRB will align with the FOV of the planned GRB detector Energetic X-ray Imaging Survey Telescope once every 9 yr. Pop III GRBs will be more easily detected by their isotropic emissions (i.e., orphan afterglows) rather than by their prompt emissions.

  17. The Potential for Detecting Gamma-Ray Burst Afterglows from Population III Stars with the Next Generation of Infrared Telescopes

    NASA Astrophysics Data System (ADS)

    Macpherson, D.; Coward, D. M.; Zadnik, M. G.

    2013-12-01

    We investigate the detectability of a proposed population of gamma-ray bursts (GRBs) from the collapse of Population III (Pop III) stars. The James Webb Space Telescope (JWST) and Space Infrared Telescope for Cosmology and Astrophysics (SPICA) will be able to observe the late time infrared afterglows. We have developed a new method to calculate their detectability, which takes into account the fundamental initial mass function and formation rates of Pop III stars, from which we find the temporal variability of the afterglows and ultimately the length of time JWST and SPICA can detect them. In the range of plausible Pop III GRB parameters, the afterglows are always detectable by these instruments during the isotropic emission, for a minimum of 55 days and a maximum of 3.7 yr. The average number of detectable afterglows will be 2.96× 10-5 per SPICA field of view (FOV) and 2.78× 10-6 per JWST FOV. These are lower limits, using a pessimistic estimate of Pop III star formation. An optimal observing strategy with SPICA could identify a candidate orphan afterglow in ~1.3 yr, with a 90% probability of confirmation with further detailed observations. A beamed GRB will align with the FOV of the planned GRB detector Energetic X-ray Imaging Survey Telescope once every 9 yr. Pop III GRBs will be more easily detected by their isotropic emissions (i.e., orphan afterglows) rather than by their prompt emissions.

  18. The Early Optical Brightening in the GRB 071010B

    SciTech Connect

    Wang, J H; Schwamb, M E; Huang, K Y; Wen, C Y; Zhang, Z W; Wang, S Y; Chen, W P; Bianco, F B; Dave, R; Lehner, M J; Marshall, S L; Porrata, R; Alcock, C; Byun, Y I; Cook, K H; King, S K; Lee, T; Urata, Y

    2008-04-08

    We report the detection of early (60-230 s) optical emission of the gamma-ray burst afterglow of GRB071010B. No significant correlation with the prompt {gamma}-ray emission was found. Our high time-resolution data combining with other measurements within 2 days after the burst indicate that GRB071010B is composed of a weak early brightening ({alpha} {approx} 0.6), probably caused by the peak frequency passing through the optical wavelengths, followed by a decay ({alpha} {approx} -0.51), attributed to continuous energy injection by patchy jets.

  19. A COMPREHENSIVE STUDY OF GAMMA-RAY BURST OPTICAL EMISSION. II. AFTERGLOW ONSET AND LATE RE-BRIGHTENING COMPONENTS

    SciTech Connect

    Liang Enwei; Li Liang; Liang Yunfeng; Tang Qingwen; Chen Jiemin; Lu Ruijing; Lue Lianzhong; Gao He; Zhang, Bing; Lue Houjun; Wu Xuefeng; Yi Shuangxi; Dai Zigao; Zhang Jin; Wei Jianyan E-mail: zhang@physics.unlv.edu

    2013-09-01

    We continue our systematic statistical study of various components of gamma-ray burst (GRB) optical light curves. We decompose the early onset bump and the late re-brightening bump with empirical fits and analyze their statistical properties. Among the 146 GRBs that have well-sampled optical light curves, the onset and re-brightening bumps are observed in 38 and 26 GRBs, respectively. It is found that the typical rising and decaying slopes for both the onset and re-brightening bumps are {approx}1.5 and {approx} - 1.15, respectively. No early onset bumps in the X-ray band are detected to be associated with the optical onset bumps, while an X-ray re-brightening bump is detected for half of the re-brightening optical bumps. The peak luminosity is anti-correlated with the peak time L{sub p}{proportional_to}t{sub p}{sup -1.81{+-}0.32} for the onset bumps and L{sub p}{proportional_to}t{sub p}{sup -0.83{+-}0.17} for the re-brightening bumps. Both L{sub p} and the isotropic energy release of the onset bumps are correlated with E{sub {gamma},iso}, whereas no similar correlation is found for the re-brightening bumps. These results suggest that the afterglow onset bumps are likely due to the deceleration of the GRB fireballs. Taking the onset bumps as probes for the properties of the fireballs and their ambient medium, we find that the typical power-law index of the relativistic electrons is 2.5 and the medium density profile behaves as n{proportional_to}r {sup -1} within the framework of the synchrotron external shock models. With the medium density profile obtained from our analysis, we also confirm the correlation between the initial Lorentz factor ({Gamma}{sub 0}) and E{sub iso,{gamma}} in our previous work. The jet component that produces the re-brightening bump seems to be on-axis and independent of the prompt emission jet component. Its typical kinetic energy budget would be about one order of magnitude larger than the prompt emission component, but with a lower {Gamma

  20. 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)

  1. Emissive sheath measurements in the afterglow of a radio frequency plasma

    SciTech Connect

    Sheehan, J. P. Hershkowitz, N.; Barnat, E. V.; Weatherford, B. R.; Kaganovich, I. D.

    2014-01-15

    The difference between the plasma potential and the floating potential of a highly emissive planar surface was measured in the afterglow of a radio frequency discharge. A Langmuir probe was used to measure the electron temperature and an emissive probe was used to measure the spatial distribution of the potential using the inflection point in the limit of zero emission technique. Time-resolved measurements were made using the slow-sweep method, a technique for measuring time-resolved current-voltage traces. This was the first time the inflection point in the limit of zero emission was used to make time-resolved measurements. Measurements of the potential profile of the presheath indicate that the potential penetrated approximately 50% farther into the plasma when a surface was emitting electrons. The experiments confirmed a recent kinetic theory of emissive sheaths, demonstrating that late in the afterglow as the plasma electron temperature approached the emitted electron temperature, the emissive sheath potential shrank to zero. However, the difference between the plasma potential and the floating potential of a highly emissive planar surface data appeared to be much less sensitive to the electron temperature ratio than the theory predicts.

  2. Constraints on the Source for Gamma-ray bursts from Observed X-Ray Afterglows

    NASA Astrophysics Data System (ADS)

    Mathews, Grant; Ruffini, Remo

    2015-04-01

    X-ray afterglows from long-duration gamma ray bursts (GRBs) are associated with energetic type Ic supernovae and the late time behavior of the afterglow from all GRBs follows the same universal normalization and power-law behavior at late times (~104 - 107 sec) when plotted relative to the time of the initial GRB trigger. We describe constraints from this afterglow on the engine for GRBs in the context of simple model for X-ray emission from accelerated relativistic electrons within an outgoing relativistic shock. We show that this universal scaling imposes 3 constraints: 1) The shock breakout energy is the same (~1051 ergs) for all bursts independently of the observed GRB luminosity; 2) After breakout, the shock propagates through an optically thin low-density (~ 1 - 10 g cm-3 medium; 3) The energy radiated by the shock is a small fraction of the total shock energy. These suggest that the late-time power-law afterglow emission derives from the underlying energetic supernova with a similar total shock energy. The correlation of the of the observed GRB energy with the luminosity of the plateau suggests a GRB engine occurring at different radii within the expanding SN consistent with the induced gravitational collapse paradigm. Work at the University of Notre Dame (GJM) supported by the U.S. Department of Energy under Nuclear Theory Grant DE-FG02-95-ER40934.

  3. The long rapid decay phase of the extended emission from the short GRB 080503

    NASA Astrophysics Data System (ADS)

    Genet, F.; Butler, N. R.; Granot, J.

    2010-06-01

    GRB 080503 was classified as a short gamma-ray burst (GRB) with extended emission. The origin of such extended emission (found in about a quarter of Swift short GRBs) is still unclear and may provide some clues to the identity of the elusive progenitors of short GRBs. The extended emission from GRB 080503 is followed by a rapid decay phase (RDP) that is detected over an unusually large dynamical range (one decade in time and ~ 3.5 decades in flux), making it ideal for studying the nature of the extended emission from short GRBs. We model the broad envelope of extended emission and the subsequent RDP using a physical model for the prompt GRB emission and its high latitude emission tail, in which the prompt emission (and its tail) is the sum of its individual pulses (and their tails). For GRB 080503, a single pulse fit is found to be unacceptable, even when ignoring short time-scale variability. The RDP displays very strong spectral evolution and shows some evidence for the presence of two spectral components with different temporal behaviour, likely arising from distinct physical regions. A two pulse fit (a first pulse accounting for the gamma-ray extended emission and decay phase, and the second pulse accounting mostly for the X-ray decay phase) provides a much better (though not perfect) fit to the data. The shallow gamma-ray and steep hard X-ray decays are hard to account for simultaneously, and require the second pulse to deviate from the simplest version of the model we use. Therefore, while high latitude emission is a viable explanation for the RDP in GRB 080503, it does not pass our tests with flying colours, and it is quite plausible that another mechanism is at work here. Finally, we note that the properties of the RDP following the extended emission of short GRBs (keeping in mind the very small number of well-studied cases so far) appear to have different properties than that following the prompt emission of long GRBs. However, a larger sample of short

  4. The LAGO Collaboration: Searching for high energy GRB emissions in Latin America

    NASA Astrophysics Data System (ADS)

    Barros, H.; Lago Collaboration

    2012-02-01

    During more than a decade Gamma Ray Bursts (GRB a cosmological phenomena of tremendous power) have been extensively studied in the keV - MeV energy range. However, the higher energy emission still remains a mystery. The Large Aperture GRB Observatory (L.A.G.O.) is an international collaboration started in 2005 aiming at a better understanding of the GRB by studying their emission at high energies (> 1 GeV), where the fluxes are low and measurements by satellites are difficult. This is done using the Single Particle Technique, by means of ground-based Water Cherenkov Detectors (WCD) at sites of high altitude. At those altitudes it is possible to detect air showers produced by high energy photons from the GRB, i. e. a higher rate of events on a short time scale, of the order of the second. The Pierre Auger Observatory could detect such GRB given its large number of detectors, but at 1400 m.a.s.l. the expected signal is quite small. At higher altitudes, similar performance is expected with only a very small number of WCD. As of 2011, high altitude WCD are in operation at Sierra Negra (Mexico, 4650 m.a.s.l.), Chacaltaya (Bolivia, 5200 m.a.s.l.), Maracapomacocha (Peru, 4200 m.a.s.l.), and new WCDs are being installed in Venezuela (Pico Espejo, 4750 m.a.s.l.), Argentina, Brazil, Chile, Colombia and Guatemala. Most of the new WCDs will not be at high enough altitude to detect GRB, never the less it will allow obtaining valuable measurements of secondaries at ground level, which are relevant for solar physics. The LAGO sensitivity to GRB is determined from simulations (under a sudden increase of 1 GeV - 1 TeV photons from a GRB) of the gamma initiated particle shower in the atmosphere and the WCD response to secondaries. We report on WDC calibration and operation at high altitude, GRB detectability, background rates, search for bursts in several months of preliminary data, as well as search for signals at ground level when satellite burst is reported, all these show the

  5. The prompt GRB high energy emission from internal shocks: synchrotron vs inverse Compton component

    SciTech Connect

    Bosnjak, Zeljka; Daigne, Frederic; Dubus, Guillaume

    2009-05-25

    We performed a detailed calculation of gamma-ray burst (GRB) prompt emission in the framework of the internal shock scenario, focusing on the high energy (GeV) bands. In order to follow the evolution of the ultrarelativistic inhomogeneous wind, we combined a model for the dynamics of internal shocks with a detailed calculation of the radiative processes occurring in the shocked medium. We present the resulting synthetic GRB light curves and spectra. We show the spectral evolution that can be expected for different sets of microphysics parameters and parameters of the dynamical evolution, and how the relative importance of synchrotron and inverse Compton components is varying during a burst.

  6. Observational Signatures of High-Energy Emission during the Shallow Decay Phase of Gamma-Ray Burst X-Ray Afterglows

    NASA Astrophysics Data System (ADS)

    Yu, Y. W.; Liu, X. W.; Dai, Z. G.

    2007-12-01

    The widely existing shallow decay phase of the X-ray afterglows of gamma-ray bursts (GRBs) is generally accepted to be due to long-lasting energy injection. The outflows carrying the injecting energy, based on the component that is dominant in energy, fall into two possible types: baryon-dominated and lepton-dominated ones. The former type of outflow could be ejecta that is ejected during the prompt phase of a GRB and consists of a series of baryonic shells with a distribution of Lorentz factors, and the latter type could be an electron-positron pair wind that is driven by the postburst central engine. We here provide a unified description for the dynamics of fireballs based on these two types of energy injection and calculate the corresponding high-energy photon emission by considering synchrotron radiation and inverse Compton scattering (including synchrotron self-Compton and combined inverse Compton) of electrons. We find that, in the two energy-injection models, there is a plateau (even a hump) in high-energy light curves during the X-ray shallow decay phase. In particular, a considerable fraction of the injecting energy in the lepton-dominated model can be shared by the long-lasting reverse shock since it is relativistic. Furthermore, almost all of the energy of the reverse shock is carried by leptons, and thus, the inverse Compton emission is enhanced dramatically. Therefore, this model predicts more significant high-energy afterglow emission than the baryon-dominated model. We argue that these observational signatures would be used to discriminate between different energy-injection models in the upcoming Gamma-Ray Large Area Space Telescope (GLAST) era.

  7. GRB 090727 AND GAMMA-RAY BURSTS WITH EARLY-TIME OPTICAL EMISSION

    SciTech Connect

    Kopac, D.; Gomboc, A.; Japelj, J.; Kobayashi, S.; Mundell, C. G.; Bersier, D.; Cano, Z.; Smith, R. J.; Steele, I. A.; Virgili, F. J.; Guidorzi, C.; Melandri, A.

    2013-07-20

    We present a multi-wavelength analysis of Swift gamma-ray burst GRB 090727, for which optical emission was detected during the prompt gamma-ray emission by the 2 m autonomous robotic Liverpool Telescope and subsequently monitored for a further two days with the Liverpool and Faulkes Telescopes. Within the context of the standard fireball model, we rule out a reverse shock origin for the early-time optical emission in GRB 090727 and instead conclude that the early-time optical flash likely corresponds to emission from an internal dissipation process. Putting GRB 090727 into a broader observational and theoretical context, we build a sample of 36 gamma-ray bursts (GRBs) with contemporaneous early-time optical and gamma-ray detections. From these GRBs, we extract a sub-sample of 18 GRBs, which show optical peaks during prompt gamma-ray emission, and perform detailed temporal and spectral analysis in gamma-ray, X-ray, and optical bands. We find that in most cases early-time optical emission shows sharp and steep behavior, and notice a rich diversity of spectral properties. Using a simple internal shock dissipation model, we show that the emission during prompt GRB phase can occur at very different frequencies via synchrotron radiation. Based on the results obtained from observations and simulation, we conclude that the standard external shock interpretation for early-time optical emission is disfavored in most cases due to sharp peaks ({Delta}t/t < 1) and steep rise/decay indices, and that internal dissipation can explain the properties of GRBs with optical peaks during gamma-ray emission.

  8. GRB 090727 and Gamma-Ray Bursts with Early-time Optical Emission

    NASA Astrophysics Data System (ADS)

    Kopač, D.; Kobayashi, S.; Gomboc, A.; Japelj, J.; Mundell, C. G.; Guidorzi, C.; Melandri, A.; Bersier, D.; Cano, Z.; Smith, R. J.; Steele, I. A.; Virgili, F. J.

    2013-07-01

    We present a multi-wavelength analysis of Swift gamma-ray burst GRB 090727, for which optical emission was detected during the prompt gamma-ray emission by the 2 m autonomous robotic Liverpool Telescope and subsequently monitored for a further two days with the Liverpool and Faulkes Telescopes. Within the context of the standard fireball model, we rule out a reverse shock origin for the early-time optical emission in GRB 090727 and instead conclude that the early-time optical flash likely corresponds to emission from an internal dissipation process. Putting GRB 090727 into a broader observational and theoretical context, we build a sample of 36 gamma-ray bursts (GRBs) with contemporaneous early-time optical and gamma-ray detections. From these GRBs, we extract a sub-sample of 18 GRBs, which show optical peaks during prompt gamma-ray emission, and perform detailed temporal and spectral analysis in gamma-ray, X-ray, and optical bands. We find that in most cases early-time optical emission shows sharp and steep behavior, and notice a rich diversity of spectral properties. Using a simple internal shock dissipation model, we show that the emission during prompt GRB phase can occur at very different frequencies via synchrotron radiation. Based on the results obtained from observations and simulation, we conclude that the standard external shock interpretation for early-time optical emission is disfavored in most cases due to sharp peaks (Δt/t < 1) and steep rise/decay indices, and that internal dissipation can explain the properties of GRBs with optical peaks during gamma-ray emission.

  9. Emission and afterglow properties of an expanding RF plasma with nonuniform neutral gas density

    NASA Astrophysics Data System (ADS)

    Chaplin, Vernon H.; Bellan, Paul M.

    2016-08-01

    We describe some notable aspects of the light emission and afterglow properties in pulsed, high-density ( 1018-1020 m-3 ) argon inductively coupled discharges initiated following fast gas injection. The plasma was created in a long, narrow discharge tube and then expanded downstream of the radiofrequency (RF) antenna into a large chamber. Fast camera images of the expanding plasma revealed a multi-phase time-dependent emission pattern that did not follow the ion density distribution. Dramatic differences in visible brightness were observed between discharges with and without an externally applied magnetic field. These phenomena were studied by tracking excited state populations using passive emission spectroscopy and are discussed in terms of the distinction between ionizing and recombining phase plasmas. Additionally, a method is presented for inferring the unknown neutral gas pressure in the discharge tube from the time-dependent visible and infrared emission measured by a simple photodiode placed near the antenna. In magnetized discharges created with fast gas injection, the downstream ion density rose by Δni˜1018 m-3 in the first ˜100 μs after the RF power was turned off. The conditions conducive to this afterglow density rise are investigated in detail, and the effect is tentatively attributed to pooling ionization.

  10. HIGH-ENERGY EMISSION OF GRB 130427A: EVIDENCE FOR INVERSE COMPTON RADIATION

    SciTech Connect

    Fan, Yi-Zhong; Zhang, Fu-Wen; He, Hao-Ning; Zhou, Bei; Yang, Rui-Zhi; Jin, Zhi-Ping; Wei, Da-Ming; Tam, P. H. T.; Liang, Yun-Feng E-mail: fwzhang@pmo.ac.cn

    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 synchrotron 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.

  11. High-energy Emission of GRB 130427A: Evidence for Inverse Compton Radiation

    NASA Astrophysics Data System (ADS)

    Fan, Yi-Zhong; Tam, P. H. T.; Zhang, Fu-Wen; Liang, Yun-Feng; He, Hao-Ning; Zhou, Bei; Yang, Rui-Zhi; Jin, Zhi-Ping; Wei, Da-Ming

    2013-10-01

    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 ~1054 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 synchrotron 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.

  12. EVIDENCE FOR A PHOTOSPHERIC COMPONENT IN THE PROMPT EMISSION OF THE SHORT GRB 120323A AND ITS EFFECTS ON THE GRB HARDNESS-LUMINOSITY RELATION

    SciTech Connect

    Guiriec, S.; McEnery, J.; Gehrels, N.; Daigne, F.; Hascoeet, R.; Mochkovitch, R.; Vianello, G.; Ryde, F.; Kouveliotou, C.; Foley, S.; McGlynn, S.; Gruber, D.

    2013-06-10

    The short GRB 120323A had the highest flux ever detected with the Gamma-Ray Burst Monitor on board the Fermi Gamma-Ray Space Telescope. Here we study its remarkable spectral properties and their evolution using two spectral models: (1) a single emission component scenario, where the spectrum is modeled by the empirical Band function (a broken power law), and (2) a two-component scenario, where thermal (a Planck-like function) emission is observed simultaneously with a non-thermal component (a Band function). We find that the latter model fits the integrated burst spectrum significantly better than the former, and that their respective spectral parameters are dramatically different: when fit with a Band function only, the E{sub peak} of the event is unusually soft for a short gamma-ray burst (GRB; 70 keV compared to an average of 300 keV), while adding a thermal component leads to more typical short GRB values (E{sub peak} {approx} 300 keV). Our time-resolved spectral analysis produces similar results. We argue here that the two-component model is the preferred interpretation for GRB 120323A based on (1) the values and evolution of the Band function parameters of the two component scenario, which are more typical for a short GRB, and (2) the appearance in the data of a significant hardness-intensity correlation, commonly found in GRBs, when we employee two-component model fits; the correlation is non-existent in the Band-only fits. GRB 110721A, a long burst with an intense photospheric emission, exhibits the exact same behavior. We conclude that GRB 120323A has a strong photospheric emission contribution, observed for the first time in a short GRB. Magnetic dissipation models are difficult to reconcile with these results, which instead favor photospheric thermal emission and fast cooling synchrotron radiation from internal shocks. Finally, we derive a possibly universal hardness-luminosity relation in the source frame using a larger set of GRBs (L{sub i}{sup Band

  13. GRB Prompt Optical Observations by Master and Lomonosov

    NASA Astrophysics Data System (ADS)

    Gorbovskoy, Evgeny

    We present the results of the prompt, early and afterglow optical observations of five γ-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations were made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the Sierra Nevada Observatory and the 2.56-m Nordic Optical Telescope. For two sources, GRB 100901A and GRB 100906A, we detected optical counterparts and obtained light curves starting before the cessation of γ-ray emission, at 113 and 48 s after the trigger, respectively. Observations of GRB 100906A were conducted in two polarizing filters. Observations of the other three bursts gave the upper limits on the optical flux; their properties are briefly discussed. A more detailed analysis of GRB 100901A and GRB 100906A, supplemented by Swift data, provides the following results and indicates different origins for the prompt optical radiation in the two bursts. The light-curve patterns and spectral distributions suggest that there is a common production site for the prompt optical and high-energy emission in GRB 100901A. The results of the spectral fits for GRB 100901A in the range from optical to X-ray favour power-law energy distributions and a consistent value of the optical extinction in the host galaxy. GRB 100906A produced a smoothly peaking optical light curve, suggesting that the prompt optical radiation in this GRB originated in a front shock. This is supported by a spectral analysis. We have found that the Amati and Ghirlanda relations are satisfied for GRB 100906A. We obtain an upper limit on the value of the optical extinction on the host of GRB 100906A. Also we consider prompt observation of dark gamma ray bursts for which on very widefield cameras MASTER-VWF and MASTER-II telescopes upper limits were received. We represent SHOCK experiment onboard the spacecraft Lomonosov.

  14. FERMI OBSERVATIONS OF HIGH-ENERGY GAMMA-RAY EMISSION FROM GRB 090217A

    SciTech Connect

    Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Borgland, A. W.; Bouvier, A.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Brez, A.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bhat, P. N.; Briggs, M. S.; Bissaldi, E.; Bonamente, E.; Brigida, M. E-mail: piron@lpta.in2p3.f

    2010-07-10

    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 9{sigma}. 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 {approx}1 GeV. All spectra are well 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.

  15. Fermi Observations of High-energy Gamma-ray Emission from GRB 090217A

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, 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.; 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.; Digel, S. W.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Favuzzi, C.; Fegan, S. J.; Ferrara, E. C.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Granot, J.; Grenier, I. A.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hadasch, D.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; 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.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Naumann-Godo, M.; 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.; Ripken, J.; 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.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; 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.; Fermi LAT Collaboration; Fermi GBM Collaboration

    2010-07-01

    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 well 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.

  16. MEASURING THE PULSE OF GRB 090618: A SIMULTANEOUS SPECTRAL AND TIMING ANALYSIS OF THE PROMPT EMISSION

    SciTech Connect

    Basak, Rupal; Rao, A. R. E-mail: arrao@tifr.res.in

    2012-01-20

    We develop a new method for simultaneous timing and spectral studies of gamma-ray burst (GRB) prompt emission and apply it to make a pulse-wise description of the prompt emission of GRB 090618, the brightest GRB detected in the Fermi era. We exploit the large area (and sensitivity) of Swift/Burst Alert Telescope and the wide bandwidth of Fermi/Gamma-ray Burst Monitor to derive the parameters for a complete spectral and timing description of the individual pulses of this GRB, based on the various empirical relations suggested in the literature. We demonstrate that this empirical model correctly describes the other observed properties of the burst, such as the variation of the lag with energy and the pulse width with energy. The measurements also show an indication of an increase in the pulse width as a function of energy at low energies for some of the pulses, which is naturally explained as an off-shoot of some particular combination of the model parameters. We argue that these model parameters, particularly the peak energy at the beginning of the pulse, are the natural choices to be used for correlation with luminosity. The implications of these results for the use of GRBs as standard candles are briefly described.

  17. Gamma-ray Burst Reverse Shock Emission in Early Radio Afterglows

    NASA Astrophysics Data System (ADS)

    Resmi, Lekshmi; Zhang, Bing

    2016-07-01

    Reverse shock (RS) emission from gamma-ray bursts is an important tool in investigating the nature of the ejecta from the central engine. If the magnetization of the ejecta is not high enough to suppress the RS, a strong RS emission component, usually peaking in the optical/IR band early on, would provide an important contribution to early afterglow light curve. In the radio band, synchrotron self-absorption may suppress early RS emission and also delay the RS peak time. In this paper, we calculate the self-absorbed RS emission in the radio band under different dynamical conditions. In particular, we stress that the RS radio emission is subject to self-absorption in both RSs and forward shocks (FSs). We calculate the ratio between the RS to FS flux at the RS peak time for different frequencies, which is a measure of the detectability of the RS emission component. We then constrain the range of physical parameters for a detectable RS, in particular the role of magnetization. We notice that unlike optical RS emission which is enhanced by moderate magnetization, moderately magnetized ejecta do not necessarily produce a brighter radio RS due to the self-absorption effect. For typical parameters, the RS emission component would not be detectable below 1 GHz unless the medium density is very low (e.g., n < 10‑3 cm‑3 for the interstellar medium and A * < 5 × 10‑4 for wind). These predictions can be tested using the afterglow observations from current and upcoming radio facilities such as the Karl G. Jansky Very Large Array, the Low-Frequency Array, the Five Hundred Meter Aperture Spherical Telescope, and the Square Kilometer Array.

  18. GRB 110709B in the induced gravitational collapse paradigm

    NASA Astrophysics Data System (ADS)

    Penacchioni, A. V.; Ruffini, R.; Bianco, C. L.; Izzo, L.; Muccino, M.; Pisani, G. B.; Rueda, J. A.

    2013-03-01

    -ray afterglow. It is most remarkable that the determination of the cosmological redshift on the basis of scaling the late X-ray afterglow, which was already verified in GRB 090618 and GRB 101023, is again verified by this analysis. Results: We find for episode 1 a temperature of the BB component that evolves with time following a broken PL, with the slope of the PL at early times α = 0 (constant function) and the slope of the PL at late times β = -4 ± 2. The break occurs at t = 41.21 s. The total energy of episode 1 is E1iso = 1.42 × 1053 erg. The total energy of episode 2 is E2iso = 2.43 × 1052 erg. We find at transparency a Lorentz factor Γ ~ 1.73 × 102, laboratory radius of 6.04 × 1013 cm, P-GRB observed temperature kTP - GRB = 12.36 keV, baryon load B = 5.7 × 10-3 and P-GRB energy of EP - GRB = 3.44 × 1050 erg. We find a remarkable coincidence of the cosmological redshift by scaling the XRT data and with three other phenomenological methods. Conclusions: We interpret GRB 110709B as a member of the IGC sources, together with GRB 970828, GRB 090618, and GRB 101023. The existence of the XRT data during the prompt phase of the emission of GRB 110709B (episode 2) offers an unprecedented tool for improving the diagnostic of GRBs emission.

  19. FERMI OBSERVATIONS OF GRB 090902B: A DISTINCT SPECTRAL COMPONENT IN THE PROMPT AND DELAYED EMISSION

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Ajello, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bhat, P. N.; Bissaldi, E.; Bonamente, E.

    2009-11-20

    We report on the observation of the bright, long gamma-ray burst (GRB), GRB 090902B, by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on-board the Fermi observatory. This was one of the brightest GRBs to have been observed by the LAT, which detected several hundred photons during the prompt phase. With a redshift of z = 1.822, this burst is among the most luminous detected by Fermi. Time-resolved spectral analysis reveals a significant power-law component in the LAT data that is distinct from the usual Band model emission that is seen in the sub-MeV energy range. This power-law component appears to extrapolate from the GeV range to the lowest energies and is more intense than the Band component, both below approx50 keV and above 100 MeV. The Band component undergoes substantial spectral evolution over the entire course of the burst, while the photon index of the power-law component remains constant for most of the prompt phase, then hardens significantly toward the end. After the prompt phase, power-law emission persists in the LAT data as late as 1 ks post-trigger, with its flux declining as t {sup -1.5}. The LAT detected a photon with the highest energy so far measured from a GRB, 33.4{sup +2.7}{sub -3.5} GeV. This event arrived 82 s after the GBM trigger and approx50 s after the prompt phase emission had ended in the GBM band. We discuss the implications of these results for models of GRB emission and for constraints on models of the extragalactic background light.

  20. CONSTRAINTS ON THE EMISSION MODEL OF THE 'NAKED-EYE BURST' GRB 080319B

    SciTech Connect

    Abdo, A. A.; Abeysekara, A. U.; Linnemann, J. T.; Allen, B. T.; Chen, C.; Aune, T.; Berley, D.; Goodman, J. A.; Christopher, G. E.; Kolterman, B. E.; Mincer, A. I.; DeYoung, T.; Dingus, B. L.; Hoffman, C. M.; Ellsworth, R. W.; Gonzalez, M. M.; Granot, J.; Hays, E.; McEnery, J. E.; Huentemeyer, P. H.; and others

    2012-07-10

    On 2008 March 19, one of the brightest gamma-ray bursts (GRBs) ever recorded was detected by several ground- and space-based instruments spanning the electromagnetic spectrum from radio to gamma rays. With a peak visual magnitude of 5.3, GRB 080319B was dubbed the 'naked-eye' GRB, as an observer under dark skies could have seen the burst without the aid of an instrument. Presented here are results from observations of the prompt phase of GRB 080319B taken with the Milagro TeV observatory. The burst was observed at an elevation angle of 47 Degree-Sign . Analysis of the data is performed using both the standard air shower method and the scaler or single-particle technique, which results in a sensitive energy range that extends from {approx}5 GeV to >20 TeV. These observations provide the only direct constraints on the properties of the high-energy gamma-ray emission from GRB 080319B at these energies. No evidence for emission is found in the Milagro data, and upper limits on the gamma-ray flux above 10 GeV are derived. The limits on emission between {approx}25 and 200 GeV are incompatible with the synchrotron self-Compton model of gamma-ray production and disfavor a corresponding range (2 eV-16 eV) of assumed synchrotron peak energies. This indicates that the optical photons and soft ({approx}650 keV) gamma rays may not be produced by the same electron population.

  1. Electromagnetic afterglows associated with gamma-ray emission coincident with binary black hole merger event GW150914

    NASA Astrophysics Data System (ADS)

    Yamazaki, Ryo; Asano, Katsuaki; Ohira, Yutaka

    2016-05-01

    The Fermi Gamma-ray Burst Monitor reported the possible detection of the gamma-ray counterpart of a binary black hole merger event, GW150914. We show that the gamma-ray emission is caused by a relativistic outflow with Lorentz factor larger than 10. Subsequently, debris outflow pushes the ambient gas to form a shock, which is responsible for the afterglow synchrotron emission. We find that the 1.4 GHz radio flux peaks at {˜ }10^5 s after the burst trigger. If the ambient matter is dense enough, with density larger than {˜ }10^{-2} cm^{-3}, then the peak radio flux is {˜ }0.1 mJy, which is detectable with radio telescopes such as the Very Large Array. The optical afterglow peaks earlier than the radio, and if the ambient matter density is larger than {˜ }0.1 cm^{-3}, the optical flux is detectable with large telescopes such as the Subaru Hyper Suprime-Cam. To reveal the currently unknown mechanisms of the outflow and its gamma-ray emission associated with the binary black hole merger event, follow-up electromagnetic observations of afterglows are important. Detection of the afterglow will localize the sky position of the gravitational wave and gamma-ray emissions, and it will support the physical association between them.

  2. 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. PMID:19228997

  3. On the nature of the short-duration GRB 050906

    NASA Astrophysics Data System (ADS)

    Levan, A. J.; Tanvir, N. R.; Jakobsson, P.; Chapman, R.; Hjorth, J.; Priddey, R. S.; Fynbo, J. P. U.; Hurley, K.; Jensen, B. L.; Johnson, R.; Gorosabel, J.; Castro-Tirado, A. J.; Jarvis, M.; Watson, D.; Wiersema, K.

    2008-02-01

    We present deep optical and infrared (IR) observations of the short-duration GRB 050906. Although no X-ray or optical/IR afterglow was discovered to deep limits, the error circle of the gamma-ray burst (GRB) (as derived from the Swift Burst Alert Telescope, or BAT) is unusual in containing the relatively local starburst galaxy IC328. This makes GRB 050906 a candidate burst from a soft gamma-ray repeater (SGR), similar to the giant flare from SGR 1806-20. The probability of chance alignment of a given BAT position with such a galaxy is small (<~1 per cent), although the size of the error circle (2.6arcmin radius) is such that a higher z origin cannot be ruled out. Indeed, the error circle also includes a moderately rich galaxy cluster at z = 0.43, which is a plausible location for the burst given the apparent preference that short-duration GRBs have for regions of high mass density. No residual optical or IR emission has been observed, in the form of either an afterglow or a later time emission from any associated supernova-like event. We discuss the constraints these limits place on the progenitor of GRB 050906 based on the expected optical signatures from both SGRs and merging compact object systems. Based on observations made with European Southern Observatory (ESO) telescopes at the Paranal Observatory under programme ID 075.D-0261. E-mail: a.j.levan@warwick.ac.uk

  4. Plastic Damping of Alfvén Waves in Magnetar Flares and Delayed Afterglow Emission

    NASA Astrophysics Data System (ADS)

    Li, Xinyu; Beloborodov, Andrei M.

    2015-12-01

    Magnetar flares generate Alfvén waves bouncing in the closed magnetosphere with energy up to ∼ {10}46 erg. We show that on a timescale of 10 ms the waves are transmitted into the star and form a compressed packet of high energy density. This packet strongly shears the stellar crust and initiates a plastic flow, heating the crust and melting it hundreds of meters below the surface. A fraction of the deposited plastic heat is eventually conducted to the stellar surface, contributing to the surface afterglow months to years after the flare. A large fraction of heat is lost to neutrino emission or conducted into the core of the neutron star.

  5. On the Electron Energy Distribution Index of Swift Gamma-ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Curran, P. A.; Evans, P. A.; de Pasquale, M.; Page, M. J.; van der Horst, A. J.

    2010-06-01

    The electron energy distribution index, p, is a fundamental parameter of the synchrotron emission from a range of astronomical sources. Here we examine one such source of synchrotron emission, gamma-ray burst (GRB) afterglows observed by the Swift satellite. Within the framework of the blast wave model, we examine the constraints placed on the distribution of p by the observed X-ray spectral indices and parameterize the distribution. We find that the observed distribution of spectral indices are inconsistent with an underlying distribution of p composed of a single discrete value but consistent with a Gaussian distribution centered at p = 2.36 and having a width of 0.59. Furthermore, accepting that the underlying distribution is a Gaussian, we find that the majority (gsim94%) of GRB afterglows in our sample have cooling break frequencies less than the X-ray frequency.

  6. Gravitational-to-electromagnetic wave conversion and gamma-ray bursts calorimetry: The GRB980425/SN 1998bw ~1049 erg radio emission

    NASA Astrophysics Data System (ADS)

    Mosquera Cuesta, Herman J.

    2002-03-01

    The unusual features of supernova (SN) 1998bw and its apparent association with the gamma-ray burst (GRB) event GRB980425 were highlighted by Kulkarni et al. At its peak SN 1998bw was anomalously superluminous in radio wavelengths with an inferred fluence Eradio>=1049 erg [S. Kulkarni et al., Nature (London) 395, 663 (1998)], while the apparent expansion velocity of its ejecta (~10-5Msolar) suggests a shock wave moving relativistically (Vexp~2c). The unique properties of SN 1998bw strengthen the case for it being linked with GRB980425. I present a consistent, novel mechanism to explain the peculiar event SN 1998bw and similar phenomena in GRBs: Conversion of powerful, high frequency (~2 kHz) gravitational waves (GWs) into electromagnetic waves [M. Johnston, R. Ruffini, and F. Zerilli, Phys. Rev. Lett. 31, 1317 (1973)] might have taken place during SN 1998bw. Yet, conversion of GRB photons into GWs, as advanced by Johnston, Ruffini, and Zerilli [Phys. Lett. 49B, 185 (1974)], may also occur. These processes can produce GRBs depleted in γ rays but enhanced in x rays, for instance, or even more plausibly induce dark GRBs, those with no optical afterglow. The class of GWs needed to drive the calorimetric changes of these gamma-ray bursts may be generated by (a) the nonaxisymmetric dynamics of a torus surrounding the hypernova (or failed supernova) magnetized stellar-mass black hole (BH) remnant, as in van Putten's mechanism for driving long GRBs powered by the BH spin energy [Phys. Rev. Lett. 87, 091101 (2001)], or in the van Putten and Ostriker mechanism to account for the bimodal distribution in duration in GRBs [Astrophys. J. Lett. 552, L32 (2001)], where the torus magnetohydrodynamics may be dominated by either hyperaccretion onto a slowly spinning BH or suspended accretion onto a fast rotating BH, or (b) the just formed black hole with electromagnetic structure as in the GRB central engine mechanism of Ruffini et al. [Astrophys. J. Lett. 555, L107 (2001); 555, L

  7. VizieR Online Data Catalog: GRB 100901A and GRB 100906A light curves (Gorbovskoy+, 2012)

    NASA Astrophysics Data System (ADS)

    Gorbovskoy, E. S.; Lipunova, G. V.; Lipunov, V. M.; Kornilov, V. G.; Belinski, A. A.; Shatskiy, N. I.; Tyurina, N. V.; Kuvshinov, D. A.; Balanutsa, P. V.; Chazov, V. V.; Kuznetsov, A.; Zimnukhov, D. S.; Kornilov, M. V.; Sankovich, A. V.; Krylov, A.; Ivanov, K. I.; Chvalaev, O.; Poleshchuk, V. A.; Konstantinov, E. N.; Gress, O. A.; Yazev, S. A.; Budnev, N. M.; Krushinski, V. V.; Zalozhnich, I. S.; Popov, A. A.; Tlatov, A. G.; Parhomenko, A. V.; Dormidontov, D. V.; Senik, V.; Yurkov, V. V.; Sergienko, Yu. P.; Varda, D.; Kudelina, I. P.; Castro-Tirado, A. J.; Gorosabel, J.; Sanchez-Ramirez, R.; Jelinek, M.; Tello, J. C.

    2012-11-01

    We present the results of the prompt, early and afterglow optical observations of five γ-ray bursts (GRBs): GRB 100901A, GRB 100902A, GRB 100905A, GRB 100906A and GRB 101020A. These observations were made with the Mobile Astronomical System of TElescope-Robots in Russia (MASTER-II Net), the 1.5-m telescope of the Sierra Nevada Observatory and the 2.56-m Nordic Optical Telescope. (5 data files).

  8. Probing the Environment of Gravitational-wave Transient Sources with TeV Afterglow Emission

    NASA Astrophysics Data System (ADS)

    Zhu, Qin-Yu; Wang, Xiang-Yu

    2016-09-01

    Recently, the Advanced Laser Interferometer Gravitational-wave Observatory detected gravitational-wave (GW) transients from mergers of binary black holes (BHs). The system may also produce a wide-angle, relativistic outflow if the claimed short gamma-ray burst detected by GBM is in real association with GW150914. It was suggested that mergers of double neutron stars (or neutron star-black hole binaries), another promising source of GW transients, also produce fast, wide-angle outflows. In this paper, we calculate the high-energy gamma-ray emission arising from the blast waves driven by these wide-angle outflows. We find that TeV emission arising from the inverse-Compton process in the relativistic outflow, originating from mergers of binary BHs that are similar to those in GW150914, could be detectable by ground-based Imaging Atmospheric Cherenkov Telescopes such as the Cherenkov Telescope Array (CTA) if the sources occur in a dense medium with a density of n≳ 0.3 {{cm}}-3. For neutron star–neutron star (NS–NS) and NS–BH mergers, TeV emission from the wide-angle, mildly relativistic outflow could be detected as well, if it occurs in a dense medium with n≳ 10{--}100 {{cm}}-3. Thus, TeV afterglow emission could be a useful probe of the environment of the GW transients, which could shed light on the evolution channels of the progenitors of GW transients.

  9. 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.; Burud, I.; Rhoads, J.; Fruchter, A.

    2003-01-01

    We report optical and near-infrared follow-up observations of GRB 011121 collected predominantly at ESO telescopes in Chile. We discover a break in the afterglow light curve after 1.3 days, which implies an initial jet opening angle of about 9 deg. The jet origin of this break is supported by the fact that the spectral energy distribution is achromatic during the first four days. During later phases, GRB 011121 shows significant excess emission above the flux predicted by a power law, which we interpret as additional light from an underlying supernova. In particular, the spectral energy distribution of the optical transient approximately 2 weeks after the burst is clearly not of power-law type, but can be presented by a black body with a temperature of approx. 6000 K. The deduced parameters for the decay slope as well as the spectral index favor a wind scenario, i.e. an outflow into a circum-burst environment shaped by the stellar wind of a massive GRB progenitor. Due to its low redshift of z=0.36, GRB 011121 has been the best example for the GRB-supernova connection until GRB 030329, and provides compelling evidence for a circum-burster wind region expected to exist if the progenitor was a massive star.

  10. Ultra-high Energy Neutrinos from Gamma-Ray Burst Afterglows Using the Swift-UVOT Data

    NASA Astrophysics Data System (ADS)

    Nir, Guy; Guetta, Dafne; Landsman, Hagar; Behar, Ehud

    2016-02-01

    We consider a sample of 107 gamma-ray bursts (GRBs) for which early ultra-violet emission was measured by Swift and extrapolate the photon intensity to lower energies. Protons accelerated in the GRB jet may interact with such photons to produce charged pions and subsequently ultra high energy neutrinos {\\varepsilon }ν ≥slant {10}16 eV. We use simple energy conversion efficiency arguments to predict the maximal neutrino flux expected from each GRB. We estimate the neutrino detection rate at large area radio based neutrino detectors and conclude that the early afterglow neutrino emission is too weak to be detected even by next generation neutrino observatories.

  11. THE LONG AND THE SHORT OF THE HIGH-ENERGY EMISSION IN GRB090926A: AN EXTERNAL SHOCK

    SciTech Connect

    Sacahui, J. R.; Fraija, N.; Gonzalez, M. M.; Lee, W. H. E-mail: nifraija@astro.unam.mx E-mail: wlee@astro.unam.mx

    2012-08-20

    Synchrotron self-Compton (SSC) emission from a reverse shock has been suggested as the origin for the high-energy component lasting 2 s in the prompt phase of GRB98080923. The model describes spectral indices, fluxes, and the duration of the high-energy component as well as a long keV tail present in the prompt phase of GRB980923. Here, we present an extension of this model to describe the high-energy emission of GRB090926A. We argue that the emission consists of two components, one with a duration less than 1 s during the prompt phase, and a second, longer-lasting GeV phase lasting hundred of seconds after the prompt phase. The short high-energy phase can be described as SSC emission from a reverse shock similar to that observed in GRB980923, while the longer component arises from the forward shock. The main assumption is that the jet is magnetized and evolves in the thick-shell case, and the calculated fluxes and break energies are all consistent with the observed values. A comparison between the resulting parameters obtained for GRB980923 and GRB090926A suggests differences in burst tails that could be attributable to the circumburst medium, and this could account for previous analyses reported in the literature for other bursts. We find that the density of the surrounding medium inferred from the observed values associated with the forward shock agrees with standard values for host galaxies such as the one associated with GRB090926A.

  12. The Ultraluminous GRB 110918A

    NASA Astrophysics Data System (ADS)

    Frederiks, D. D.; Hurley, K.; Svinkin, D. S.; Pal'shin, V. D.; Mangano, V.; Oates, S.; Aptekar, R. L.; Golenetskii, S. V.; Mazets, E. P.; Oleynik, Ph. P.; Tsvetkova, A. E.; Ulanov, M. V.; Kokomov, A. A.; Cline, T. L.; Burrows, D. N.; Krimm, H. A.; Pagani, C.; Sbarufatti, B.; Siegel, M. H.; Mitrofanov, I. G.; Golovin, D.; Litvak, M. L.; Sanin, A. B.; Boynton, W.; Fellows, C.; Harshman, K.; Enos, H.; Starr, R.; von Kienlin, A.; Rau, A.; Zhang, X.; Goldstein, J.

    2013-12-01

    GRB 110918A is the brightest long gamma-ray burst (GRB) detected by Konus-WIND during its almost 19 yr of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final Interplanetary Network localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderate peak energy of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z = 0.984, a huge isotropic-equivalent energy release E iso = (2.1 ± 0.1) × 1054 erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity L iso = (4.7 ± 0.2) × 1054 erg s-1. A tail of the soft γ-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. The Swift/X-Ray Telescope and the Swift/Ultraviolet Optical Telescope observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and interstellar-medium-like circumburst environment implied. We conclude that, among the multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.°7-3.°4 results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of z ~ 7.5 for Konus-WIND and z ~ 12 for the Swift/Burst Alert Telescope, which stresses the importance of GRBs as probes of the early Universe.

  13. The ultraluminous GRB 110918A

    SciTech Connect

    Frederiks, D. D.; Svinkin, D. S.; Pal'shin, V. D.; Aptekar, R. L.; Golenetskii, S. V.; Mazets, E. P.; Oleynik, Ph. P.; Tsvetkova, A. E.; Ulanov, M. V.; Kokomov, A. A.; Hurley, K.; Mangano, V.; Burrows, D. N.; Sbarufatti, B.; Siegel, M. H.; Oates, S.; Cline, T. L.; Krimm, H. A.; Pagani, C.; Mitrofanov, I. G. [Space Research Institute, Profsoyuznaya 84 and others

    2013-12-20

    GRB 110918A is the brightest long gamma-ray burst (GRB) detected by Konus-WIND during its almost 19 yr of continuous observations and the most luminous GRB ever observed since the beginning of the cosmological era in 1997. We report on the final Interplanetary Network localization of this event and its detailed multiwavelength study with a number of space-based instruments. The prompt emission is characterized by a typical duration, a moderate peak energy of the time-integrated spectrum, and strong hard-to-soft evolution. The high observed energy fluence yields, at z = 0.984, a huge isotropic-equivalent energy release E {sub iso} = (2.1 ± 0.1) × 10{sup 54} erg. The record-breaking energy flux observed at the peak of the short, bright, hard initial pulse results in an unprecedented isotropic-equivalent luminosity L {sub iso} = (4.7 ± 0.2) × 10{sup 54} erg s{sup –1}. A tail of the soft γ-ray emission was detected with temporal and spectral behavior typical of that predicted by the synchrotron forward-shock model. The Swift/X-Ray Telescope and the Swift/Ultraviolet Optical Telescope observed the bright afterglow from 1.2 to 48 days after the burst and revealed no evidence of a jet break. The post-break scenario for the afterglow is preferred from our analysis, with a hard underlying electron spectrum and interstellar-medium-like circumburst environment implied. We conclude that, among the multiple reasons investigated, the tight collimation of the jet must have been a key ingredient to produce this unusually bright burst. The inferred jet opening angle of 1.°7-3.°4 results in reasonable values of the collimation-corrected radiated energy and the peak luminosity, which, however, are still at the top of their distributions for such tightly collimated events. We estimate a detection horizon for a similar ultraluminous GRB of z ∼ 7.5 for Konus-WIND and z ∼ 12 for the Swift/Burst Alert Telescope, which stresses the importance of GRBs as probes of the early

  14. A Fe K Line in GRB 970508

    NASA Astrophysics Data System (ADS)

    Protassov, R.; van Dyk, D.; Connors, A.; Kashyap, V.; Siemiginowska, A.

    2000-12-01

    We examine the x-ray spectrum of the afterglow of GRB 970508, analyzed for Fe line emission by Piro et al (1999, ApJL, 514, L73). This is a difficult and extremely important measurement: the detection of x-ray afterglows from γ -ray bursts is at best a tricky business, relying on near-real satellite time response to unpredictable events; and a great deal of luck in catching a burst bright enough for a useful spectral analysis. Detecting a clear atomic (or cyclotron) line in the generally smooth and featureless afterglow (or burst) emission not only gives one of the few very specific keys to the physics local to the emission region, but also provides clues or confirmation of its distance (via redshift). Unfortunately, neither the likelihood ratio test or the related F-statistic commonly used to detect spectral lines adhere to their nominal Chi square and F-distributions. Thus we begin by calibrating the F-statistic used in Piro et al (1999, ApJL, 514, L73) via a simulation study. The simulation study relies on a completely specified source model, i.e. we do Monte Carlo simulations with all model parameters fixed (so--called ``parametric bootstrapping''). Second, we employ the method of posterior predictive p-values to calibrate a LRT statistic while accounting for the uncertainty in the parameters of the source model. Our analysis reveals evidence for the Fe K line.

  15. Physical Processes Shaping Gamma-Ray Burst X-Ray Afterglow Light Curves: Theoretical Implications from the Swift X-Ray Telescope Observations

    NASA Astrophysics Data System (ADS)

    Zhang, Bing; Fan, Y. Z.; Dyks, Jaroslaw; Kobayashi, Shiho; Mészáros, Peter; Burrows, David N.; Nousek, John A.; Gehrels, Neil

    2006-05-01

    With the successful launch of the Swift Gamma-Ray Burst Explorer, a rich trove of early X-ray afterglow data has been collected by its onboard X-Ray Telescope (XRT). Some interesting features are emerging, including a distinct rapidly decaying component preceding the conventional afterglow component in many sources, a shallow decay component before the more ``normal'' decay component observed in a good fraction of GRBs, and X-ray flares in nearly half of the afterglows. In this paper we systematically analyze the possible physical processes that shape the properties of the early X-ray afterglow light curves and use the data to constrain various models. We suggest that the steep decay component is consistent with the tail emission of the prompt gamma-ray bursts and/or the X-ray flares. This provides strong evidence that the prompt emission and afterglow emission are likely two distinct components, supporting the internal origin of the GRB prompt emission. The shallow decay segment observed in a group of GRBs suggests that very likely the forward shock keeps being refreshed for some time. This might be caused by either a long-lived central engine, or a wide distribution of the shell Lorentz factors, or else possibly the deceleration of a Poynting flux-dominated flow. X-ray flares suggest that the GRB central engine is very likely still active after the prompt gamma-ray emission is over, but with a reduced activity at later times. In some cases, the central engine activity even extends to days after the burst triggers. Analyses of early X-ray afterglow data reveal that GRBs are indeed highly relativistic events and that early afterglow data of many bursts, starting from the beginning of the XRT observations, are consistent with the afterglow emission from an ISM environment.

  16. DETECTION OF A THERMAL SPECTRAL COMPONENT IN THE PROMPT EMISSION OF GRB 100724B

    SciTech Connect

    Guiriec, Sylvain; Connaughton, Valerie; Briggs, Michael S.; Burgess, Michael; Goldstein, Adam; Bhat, P.N.; Chaplin, Vandiver; Ryde, Felix; Daigne, Frederic; Meszaros, Peter; McEnery, Julie; Omodei, Nicola; Bissaldi, Elisabetta; Diehl, Roland; Foley, Suzanne; Greiner, Jochen; Camero-Arranz, Ascension; Fishman, Gerald

    2011-02-01

    Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor find that the spectrum is dominated by the typical Band functional form, which is usually taken to represent a non-thermal emission component, but also includes a statistically highly significant thermal spectral contribution. The simultaneous observation of the thermal and non-thermal components allows us to confidently identify the two emission components. The fact that these seem to vary independently favors the idea that the thermal component is of photospheric origin while the dominant non-thermal emission occurs at larger radii. Our results imply either a very high efficiency for the non-thermal process or a very small size of the region at the base of the flow, both quite challenging for the standard fireball model. These problems are resolved if the jet is initially highly magnetized and has a substantial Poynting flux.

  17. Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B

    NASA Astrophysics Data System (ADS)

    Guiriec, Sylvain; Connaughton, Valerie; Briggs, Michael S.; Burgess, Michael; Ryde, Felix; Daigne, Frédéric; Mészáros, Peter; Goldstein, Adam; McEnery, Julie; Omodei, Nicola; Bhat, P. N.; Bissaldi, Elisabetta; Camero-Arranz, Ascensión; Chaplin, Vandiver; Diehl, Roland; Fishman, Gerald; Foley, Suzanne; Gibby, Melissa; Giles, Misty M.; Greiner, Jochen; Gruber, David; von Kienlin, Andreas; Kippen, Marc; Kouveliotou, Chryssa; McBreen, Sheila; Meegan, Charles A.; Paciesas, William; Preece, Robert; Rau, Arne; Tierney, Dave; van der Horst, Alexander J.; Wilson-Hodge, Colleen

    2011-02-01

    Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor find that the spectrum is dominated by the typical Band functional form, which is usually taken to represent a non-thermal emission component, but also includes a statistically highly significant thermal spectral contribution. The simultaneous observation of the thermal and non-thermal components allows us to confidently identify the two emission components. The fact that these seem to vary independently favors the idea that the thermal component is of photospheric origin while the dominant non-thermal emission occurs at larger radii. Our results imply either a very high efficiency for the non-thermal process or a very small size of the region at the base of the flow, both quite challenging for the standard fireball model. These problems are resolved if the jet is initially highly magnetized and has a substantial Poynting flux.

  18. TWO POPULATIONS OF GAMMA-RAY BURST RADIO AFTERGLOWS

    SciTech Connect

    Hancock, P. J.; Gaensler, B. M.; Murphy, T.

    2013-10-20

    The detection rate of gamma-ray burst (GRB) afterglows is ∼30% at radio wavelengths, much lower than in the X-ray (∼95%) or optical (∼70%) bands. The cause of this low radio detection rate has previously been attributed to limited observing sensitivity. We use visibility stacking to test this idea, and conclude that the low detection rate is instead due to two intrinsically different populations of GRBs: radio-bright and radio-faint. We calculate that no more than 70% of GRB afterglows are truly radio-bright, leaving a significant population of GRBs that lack a radio afterglow. These radio-bright GRBs have higher gamma-ray fluence, isotropic energies, X-ray fluxes, and optical fluxes than the radio-faint GRBs, thus confirming the existence of two physically distinct populations. We suggest that the gamma-ray efficiency of the prompt emission is responsible for the difference between the two populations. We also discuss the implications for future radio and optical surveys.

  19. AGILE DETECTION OF DELAYED GAMMA-RAY EMISSION FROM THE SHORT GAMMA-RAY BURST GRB 090510

    SciTech Connect

    Giuliani, A.; Vianello, G.; Mereghetti, S.; Caraveo, P.; Chen, A. W.; Contessi, T.; Barbiellini, G.; Longo, F.; Moretti, E.; Cattaneo, P. W.

    2010-01-10

    Short gamma-ray bursts (GRBs), typically lasting less than 2 s, are a special class of GRBs of great interest. We report the detection by the AGILE satellite of the short GRB 090510 which shows two clearly distinct emission phases: a prompt phase lasting {approx}200 ms and a second phase lasting tens of seconds. The prompt phase is relatively intense in the 0.3-10 MeV range with a spectrum characterized by a large peak/cutoff energy near 3 MeV; in this phase, no significant high-energy gamma-ray emission is detected. At the end of the prompt phase, intense gamma-ray emission above 30 MeV is detected showing a power-law time decay of the flux of the type t {sup -1.3} and a broadband spectrum remarkably different from that of the prompt phase. It extends from sub-MeV to hundreds of MeV energies with a photon index {alpha} {approx_equal} 1.5. GRB 090510 provides the first case of a short GRB with delayed gamma-ray emission. We present the timing and spectral data of GRB 090510 and briefly discuss its remarkable properties within the current models of gamma-ray emission of short GRBs.

  20. From a Better Understanding of GRB Prompt Emission to a New Type of Standard Candles?

    NASA Astrophysics Data System (ADS)

    Guiriec, Sylvain

    2016-07-01

    Recent results revealed the simultaneous existence of multiple components in the prompt emission of gamma-ray bursts (GRBs) leading to a unified spectro-temporal model for the broadband spectrum from the optical regime up to higher gamma rays. Unexpectedly, we discovered a relation intrinsic to one specific component of this model: its luminosity is strongly and tightly correlated to its spectral break energy. This new luminosity-hardness relation has the same index for all GRBs when fitted to a power law. In addition, this relation seems to have the same normalization for all GRBs; therefore, this is a promising and physically motivated tool that may establish GRBs as cosmological standard candles. During this presentation, I will introduce this new relation, which might eventually be used to (i) estimate GRB distances, (ii) to support searches for gravitational waves and cosmic high-energy neutrinos, and (iii) constrain the cosmological parameters. I will give a few examples of GRB redshift estimates using this relation and I will show why this new result cannot solely be explain by instrumental selection effects and/or measurement/analysis biases.

  1. Shallow Decay of Early X-Ray Afterglows from Inhomogeneous Gamma-Ray Burst Jets

    NASA Astrophysics Data System (ADS)

    Toma, Kenji; Ioka, Kunihito; Yamazaki, Ryo; Nakamura, Takashi

    2006-04-01

    Almost all the X-ray afterglows of γ-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase in their first few thousand seconds. We show that in an inhomogeneous-jet model (multiple-subjet or patchy-shell), the superposition of the afterglows of off-axis subjets (patchy shells) can produce the shallow decay phase. The necessary condition for obtaining the shallow decay phase is that γ-ray-bright subjets (patchy shells) have γ-ray efficiencies higher than previously estimated and that they be surrounded by γ-ray-dim subjets (patchy shells) with low γ-ray efficiency. Our model predicts that events with dim prompt emission will have a conventional afterglow light curve without a shallow decay phase, like GRB 050416A.

  2. GRB neutrino search with MAGIC

    SciTech Connect

    Becker, Julia K.; Rhode, Wolfgang; Gaug, Markus

    2008-05-22

    The Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope was designed for the detection of photon sources > or approx. 50 GeV. The measurement of highly-inclined air showers renders possible the search for high-energy neutrinos, too. Only neutrinos can traverse the Earth without interaction, and therefore, events close to the horizon can be identified as neutrino-induced rather than photon-induced or hadronic events. In this paper, Swift-XRT-detected GRBs with given spectral information are used in order to calculate the potential neutrino energy spectrum from prompt and afterglow emission for each individual GRB. The event rate in MAGIC is estimated assuming that the GRB happens within the field of view of MAGIC. A sample of 568 long GRBs as detected by BATSE is used to compare the detection rates with 163 Swift-detected bursts. BATSE has properties similar to the Gamma-ray Burst Monitor (GBM) on board of GLAST. Therefore the estimated rates give an estimate for the possibilities of neutrino detection with MAGIC from GLAST-triggered bursts.

  3. Toward an Understanding of GRB Prompt Emission Mechanism. I. The Origin of Spectral Lags

    NASA Astrophysics Data System (ADS)

    Uhm, Z. Lucas; Zhang, Bing

    2016-07-01

    Despite decades of investigations, the physical mechanism that powers the bright prompt γ-ray emission from gamma-ray bursts (GRBs) is still not identified. One important observational clue that still has not been properly interpreted is the existence of time lags of broad light curve pulses in different energy bands, referred to as “spectral lags.” Here, we show that the traditional view invoking the high-latitude emission “curvature effect” of a relativistic jet cannot account for spectral lags. Rather, the observed spectral lags demand the sweep of a spectral peak across the observing energy band in a specific manner. The duration of the broad pulses and inferred typical Lorentz factor of GRBs require that the emission region be in an optically thin emission region far from the GRB central engine. We construct a simple physical model invoking synchrotron radiation from a rapidly expanding outflow. We show that the observed spectral lags appear naturally in our model light curves given that (1) the gamma-ray photon spectrum is curved (as observed), (2) the magnetic field strength in the emitting region decreases with radius as the region expands in space, and (3) the emission region itself undergoes rapid bulk acceleration as the prompt γ-rays are produced. These requirements are consistent with a Poynting-flux-dominated jet abruptly dissipating magnetic energy at a large distance from the engine.

  4. On the Non-existence of a Sharp Cooling Break in Gamma-Ray Burst Afterglow Spectra

    NASA Astrophysics Data System (ADS)

    Uhm, Z. Lucas; Zhang, Bing

    2014-01-01

    Although the widely used analytical afterglow model of gamma-ray bursts (GRBs) predicts a sharp cooling break ν c in its afterglow spectrum, the GRB observations so far rarely show clear evidence for a cooling break in their spectra or a corresponding temporal break in their light curves. Employing a Lagrangian description of the blast wave, we conduct a sophisticated calculation of the afterglow emission. We precisely follow the cooling history of non-thermal electrons accelerated into each Lagrangian shell. We show that a detailed calculation of afterglow spectra does not in fact give rise to a sharp cooling break at ν c . Instead, it displays a very mild and smooth transition, which occurs gradually over a few orders of magnitude in energy or frequency. The main source of this slow transition is that different mini shells have different evolutionary histories of the comoving magnetic field strength B, so that deriving the current value of ν c of each mini shell requires an integration of its cooling rate over the time elapsed since its creation. We present the time evolution of optical and X-ray spectral indices to demonstrate the slow transition of spectral regimes and discuss the implications of our result in interpreting GRB afterglow data.

  5. On the non-existence of a sharp cooling break in gamma-ray burst afterglow spectra

    SciTech Connect

    Uhm, Z. Lucas; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2014-01-01

    Although the widely used analytical afterglow model of gamma-ray bursts (GRBs) predicts a sharp cooling break ν {sub c} in its afterglow spectrum, the GRB observations so far rarely show clear evidence for a cooling break in their spectra or a corresponding temporal break in their light curves. Employing a Lagrangian description of the blast wave, we conduct a sophisticated calculation of the afterglow emission. We precisely follow the cooling history of non-thermal electrons accelerated into each Lagrangian shell. We show that a detailed calculation of afterglow spectra does not in fact give rise to a sharp cooling break at ν {sub c}. Instead, it displays a very mild and smooth transition, which occurs gradually over a few orders of magnitude in energy or frequency. The main source of this slow transition is that different mini shells have different evolutionary histories of the comoving magnetic field strength B, so that deriving the current value of ν {sub c} of each mini shell requires an integration of its cooling rate over the time elapsed since its creation. We present the time evolution of optical and X-ray spectral indices to demonstrate the slow transition of spectral regimes and discuss the implications of our result in interpreting GRB afterglow data.

  6. Decay phases of Swift X-ray afterglows and the forward-shock model.

    PubMed

    Panaitescu, A

    2007-05-15

    The X-ray flux of the gamma-ray burst (GRB) afterglows monitored by the Swift satellite from January 2005 to July 2006 displays one to four phases of flux power-law decay. In chronological order, they are: the GRB tail, the 'hump', the standard decay and the post-jet-break decay. More than half of the GRB tails can be identified with the large-angle emission produced during the burst (but arriving later at observer). The remaining, slower GRB tails imply that the gamma-ray mechanism continues to radiate after the burst, as also suggested by the frequent occurrence of X-ray flares during the burst tail. The several GRB tails exhibiting a slow unbroken power-law decay until 100ks must be attributed to the forward shock. In fact, the decay of most GRB tails is also consistent with that of the forward-shock emission from a narrow jet. The X-ray light-curve hump may be due to an increase of the kinetic energy per solid angle of the forward-shock region visible to the observer, caused by either the transfer of energy from ejecta to the forward shock or the emergence of the emission from an outflow seen from a location outside the jet opening. The decay following the X-ray light-curve hump is consistent with the emission from an adiabatic blast wave but, contrary to expectations, the light-curve decay index and spectral slope during this phase are not correlated. The X-ray light curves of two dozens X-ray afterglows that followed for more than a week do not exhibit a jet break, in contrast with the behaviour of pre-Swift optical afterglows, which displayed jet breaks at 0.5-2 days. Nevertheless, the X-ray light curves of several Swift afterglows show a second steepening break at 0.4-3 days that is consistent with the break expected for a jet when its edge becomes visible to the observer. PMID:17293326

  7. Soft X-ray observation of the prompt emission of GRB 100418A

    NASA Astrophysics Data System (ADS)

    Imatani, Ritsuko; Tomida, Hiroshi; Nakahira, Satoshi; Kimura, Masashi; Sakamoto, Takanori; Arimoto, Makoto; Morooka, Yoshitaka; Yonetoku, Daisuke; Kawai, Nobuyuki; Tsunemi, Hiroshi

    2015-09-01

    We have observed the prompt emission of GRB 100418A from its beginning captured by the MAXI SSC (0.7-7 keV) on board the International Space Station followed by the Swift XRT (0.3-10 keV) observation. The light curve can be fitted by a combination of a power-law component and an exponential component (the decay constant is 31.6 ± 1.6 s). The X-ray spectrum is well expressed by the Band function with Ep ≤ 8.3 keV. This is the brightest gamma-ray burst showing a very low value of Ep. It satisfies the Yonetoku relation (Ep-Lp). It is also consistent with the Amati relation (Ep-Eiso) within a 2.5σ level.

  8. Soft X-ray observation of the prompt emission of GRB 100418A

    NASA Astrophysics Data System (ADS)

    Imatani, Ritsuko; Tomida, Hiroshi; Nakahira, Satoshi; Kimura, Masashi; Sakamoto, Takanori; Arimoto, Makoto; Morooka, Yoshitaka; Yonetoku, Daisuke; Kawai, Nobuyuki; Tsunemi, Hiroshi

    2016-06-01

    We have observed the prompt emission of GRB 100418A from its beginning captured by the MAXI SSC (0.7-7 keV) on board the International Space Station followed by the Swift XRT (0.3-10 keV) observation. The light curve can be fitted by a combination of a power-law component and an exponential component (the decay constant is 31.6 ± 1.6 s). The X-ray spectrum is well expressed by the Band function with Ep ≤ 8.3 keV. This is the brightest gamma-ray burst showing a very low value of Ep. It satisfies the Yonetoku relation (Ep-Lp). It is also consistent with the Amati relation (Ep-Eiso) within a 2.5σ level.

  9. Near-extremal Black Holes as Initial Conditions of Long GRB Supernovae and Probes of Their Gravitational Wave Emission

    NASA Astrophysics Data System (ADS)

    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 Ep,i-Eiso 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 GRBs 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.

  10. GRB 141221A: gone is the wind

    NASA Astrophysics Data System (ADS)

    Bardho, O.; Gendre, B.; Rossi, A.; Amati, L.; Haislip, J.; Klotz, A.; Palazzi, E.; Reichart, D.; Trotter, A. S.; Boër, M.

    2016-06-01

    GRB 141221A was observed from infrared to soft gamma-ray bands. Here, we investigate its properties, in light of the standard model. We find that the optical light curve of the afterglow of this burst presents an unusual steep/quick rise. The broad-band spectral energy distribution taken near the maximum of the optical emission presents either a thermal component or a spectral break. In the former case, the properties of the afterglow are then very unusual, but could explain the lack of apparent jet breaks in the Swift light curves. In the latter case, the afterglow properties of this burst are more usual, and we can see in the light curves the passing through of the injection and cooling frequencies within the optical bands, not masked by a reverse shock. This model also excludes the presence of a stellar wind, challenging either the stellar progenitor properties, or the very stellar nature of the progenitor itself. In all cases, this burst may be a part of a Rosetta stone that could help to explain some of the most striking features discovered by Swift during the last 10 years.

  11. A Supramassive Magnetar Central Engine for GRB 130603B

    NASA Astrophysics Data System (ADS)

    Fan, Yi-Zhong; Yu, Yun-Wei; Xu, Dong; Jin, Zhi-Ping; Wu, Xue-Feng; Wei, Da-Ming; Zhang, Bing

    2013-12-01

    We show that the peculiar early optical emission and, in particular, the X-ray afterglow emission of the short-duration burst GRB 130603B can be explained by continuous energy injection into the blastwave from a supramassive magnetar central engine. The observed energetics and temporal/spectral properties of the late infrared bump (i.e., the "kilonova") are also found to be consistent with emission from the ejecta launched during a neutron star (NS)-NS merger and powered by a magnetar central engine. The isotropic-equivalent kinetic energies of both the gamma-ray burst (GRB) blastwave and the kilonova are approximately Ek ~ 1051 erg, consistent with being powered by a near-isotropic magnetar wind. However, this relatively small value requires that most of the initial rotational energy of the magnetar (~a few × 1052 erg) is carried away by gravitational wave radiation. Our results suggest that (1) the progenitor of GRB 130603B was a NS-NS binary system, the merger product of which would have been a supramassive NS that lasted for about ~1000 s (2) the equation of state of the nuclear matter should be stiff enough to allow the survival of a long-lived supramassive NS; thus this suggested that the detection of the bright electromagnetic counterparts of gravitational wave triggers without short GRB associations is promising in the upcoming Advanced LIGO/VIRGO era.

  12. Multicolor observations of the afterglow of the short/hard GRB 050724

    NASA Astrophysics Data System (ADS)

    Malesani, D.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Fugazza, D.; Piranomonte, S.; Ballo, L.; Campana, S.; Stella, L.; Tagliaferri, G.; Antonelli, L. A.; Chincarini, G.; Della Valle, M.; Goldoni, P.; Guidorzi, C.; Israel, G. L.; Lazzati, D.; Melandri, A.; Pellizza, L. J.; Romano, P.; Stratta, G.; Vergani, S. D.

    2007-10-01

    Context: New information on short/hard gamma-ray bursts (GRBs) is being gathered thanks to the discovery of their optical and X-ray afterglows. However, some key aspects are still poorly understood, including the collimation level of the outflow, the duration of the central engine activity, and the properties of the progenitor systems. Aims: We want to constrain the physical properties of the short GRB 050724 and of its host galaxy, and make some inferences on the global short GRB population. Methods: We present optical observations of the afterglow of GRB 050724 and of its host galaxy, significantly expanding the existing dataset for this event. We compare our results with models, complementing them with available measurements from the literature. We study the afterglow light curve and spectrum including X-ray data. We also present observations of the host galaxy. Results: The observed optical emission was likely related to the large flare observed in the X-ray light curve. The apparent steep decay was therefore not due to the jet effect. Available data are indeed consistent with low collimation, in turn implying a large energy release, comparable to that of long GRBs. The flare properties also constrain the internal shock mechanism, requiring a large Lorentz factor contrast between the colliding shells. This implies that the central engine was active at late times, rather than ejecting all shells simultaneously. The host galaxy has red colors and no ongoing star formation, consistent with previous findings on this GRB. However, it is not a pure elliptical, and has some faint spiral structure. Conclusions: GRB 050724 provides the most compelling case for association between a short burst and a galaxy with old stellar population. It thus plays a pivotal role in constraining progenitors models, which should allow for long delays between birth and explosion. Based on observations carried out at ESO telescopes under programmes Id 075.D-0787, 075.D-0468 and 078.D-0809.

  13. Signs of magnetic acceleration and multizone emission in GRB 080825C

    NASA Astrophysics Data System (ADS)

    Moretti, Elena; Axelsson, Magnus

    2016-05-01

    One of the major results from the study of gamma-ray bursts with the Fermi Gamma-ray Space Telescope has been the confirmation that several emission components can be present in the energy spectrum. Here, we reanalyse the spectrum of GRB 080825C using data from the Fermi-Large Area Telescope (LAT) and Gamma-ray Burst Monitor instruments. Although fairly weak, it is the first gamma-ray burst detected by the Fermi-LAT. We improve on the original analysis by using the LAT Low Energy events covering the 30-100 MeV band. We find evidence of an additional component above the main emission peak (modelled using a Band function) with a significance of 3.5σ in two out of the four time bins. The component is well fitted by a Planck function, but shows unusual behaviour: the peak energy increases in the prompt emission phase, reaching energies of several MeV. This is the first time such a trend has been seen, and implies that the origin of this component is different from those previously detected. We suggest that the two spectral components likely arise in different regions of the outflow, and that strong constraints can be achieved by assuming one of them originates from the photosphere. The most promising model appears to be that the high-energy peak is the result of photospheric emission in a Poynting flux dominated outflow where the magnetization increases with time.

  14. Afterglow Population Studies from Swift Follow-Up Observations of Fermi LAT GRBs

    NASA Technical Reports Server (NTRS)

    Racusin, Judith L.; Oates, S. R.; McEnery, J.; Vasileiou, V.; Troja, E.; Gehrels, N.

    2010-01-01

    The small population of Fermi LAT detected GRBs discovered over the last year has been providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 5 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into other components of GRB emission structure. We explore the new ability to utilize both of these observatories to study the same GRBs over 10 orders of magnitude in energy, although not always concurrently. Almost all LAT GRBs that have been followed-up by Swift within 1-day have been clearly detected and carefully observed. We will present the context of the lower-energy afterglows of this special subset of GRBs that has > 100 MeV emission compared to the hundreds in the Swift database that may or may not have been observed by LAT, and theorize upon the relationship between these properties and the origin of the high energy gamma-ray emission.

  15. GRB 030329 with SARA and TLS

    NASA Astrophysics Data System (ADS)

    Lindsay, K.; Zeh, A.; Hartmann, D. H.; Klose, S.; Shaw, S.; Leake, M.; Webb, J.; Stecklum, B.; Williams, M.; Howard, E.

    2004-09-01

    We present B band observations performed with the SARA 0.9m telescope at KPNO and the Tautenburg 1.34m Schmidt telescope in Tautenburg, Germany, for the optical afterglow of the gamma-ray burst GRB 030329. Observations were carried out from March 30.12 to April 8.29 (UT) with SARA, and from March 30.80 to April 7.00 (UT) with the Tautenburg Schmidt. This burst provides the best covered GRB afterglow light curve to date. The afterglow exhibits a complicated ``fine structure'' with several episodes of significant re-brightening. These episodes inevitably demand a more detailed numerical fit which introduces a larger number of free parameters. It is difficult to separate the light from the re-brightening phases and the light from the underlying supernova. The photometric data show an average temporal regression in the flux of the optical afterglow, that is typical for GRB afterglow. However, ``bumps and wiggles'' clearly suggest a degree of complexity resulting from the re-brightening phases that is not easily fitted with standard models. At late time the light curve receives a significant contribution from an underlying supernova component (SN 2002dh). We argue that in cases such as GRB 030329 single site observations are inadequate to properly sample the evolving flux. Consequently, simple broken power law fits of data obtained with just one telescope may lead to rather poor descriptions of the afterglow charcateristics.

  16. The Swift XRT: Observations of Early X-ray Afterglows

    SciTech Connect

    Burrows, David N.; Kennea, J. A.; Nousek, J. A.; Osborne, J. P.; O'Brien, P. T.; Chincarini, G.; Tagliaferri, G.; Giommi, P.; Zhang, B.

    2006-05-19

    During the first year of operations of the Swift observatory, the X-ray Telescope has made a number of discoveries concerning the nature of X-ray afterglows of both long and short GRBs. We highlight the key findings, which include rapid declines at early times, a standard template of afterglow light curve shapes, common flaring, and the discovery of the first short GRB afterglow.

  17. GRB 110205A: ANATOMY OF A LONG GAMMA-RAY BURST

    SciTech Connect

    Gendre, B.; Stratta, G.; Atteia, J. L.; Klotz, A.; Boeer, M.; Colas, F.; Vachier, F.; Kugel, F.; Rinner, C.; Laas-Bourez, M.

    2012-03-20

    The Swift burst GRB 110205A was a very bright burst visible in the Northern Hemisphere. GRB 110205A was intrinsically long and very energetic and it occurred in a low-density interstellar medium environment, leading to delayed afterglow emission and a clear temporal separation of the main emitting components: prompt emission, reverse shock, and forward shock. Our observations show several remarkable features of GRB 110205A: the detection of prompt optical emission strongly correlated with the Burst Alert Telescope light curve, with no temporal lag between the two; the absence of correlation of the X-ray emission compared to the optical and high-energy gamma-ray ones during the prompt phase; and a large optical re-brightening after the end of the prompt phase, that we interpret as a signature of the reverse shock. Beyond the pedagogical value offered by the excellent multi-wavelength coverage of a gamma-ray burst with temporally separated radiating components, we discuss several questions raised by our observations: the nature of the prompt optical emission and the spectral evolution of the prompt emission at high energies (from 0.5 keV to 150 keV); the origin of an X-ray flare at the beginning of the forward shock; and the modeling of the afterglow, including the reverse shock, in the framework of the classical fireball model.

  18. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    NASA Technical Reports Server (NTRS)

    Racusin, Judith I.

    2011-01-01

    The new and extreme population of GRBs detected by Fermi-LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT GRBs and the well studied, fainter, less energetic GRBs detected by Swift-BAT is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi-GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  19. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    NASA Technical Reports Server (NTRS)

    Racusin, J. L.; Oates, S. R.; Schady, P.; Burrows, D. N.; de Pasquale, M.; Donato, D.; Gehrels, N.; Koch, S.; McEnery, J.; Piran, T.; Roming, P.; Sakamoto, T.; Swenson, C.; Virgili, F.; Wanderman, D.; Zhang, B.

    2011-01-01

    The new and extreme population of GRBs detected by Fermi-LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT GRBs and the well studied, fainter, less energetic GRBs detected by Swift-BAT is only beginning to be explored by multiwavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi-GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  20. Fermi and Swift Gamma-Ray Burst Afterglow Population Studies

    NASA Technical Reports Server (NTRS)

    Racusin, Judith L.; Oates, S. R.; Schady, P.; Burrows, D. N.; dePasquale, M.; Donato, D.; Gehrels, N.; Koch, S.; McEnery, J.; Piran, T.; Roming, P.; Sakamoto, T.; Swenson, C.; Troja, E.; Vasileiou, V.; Virgili, F.; Wanderman, D.; Zhang, B.

    2011-01-01

    The new and extreme population of GRBs detected by Fermi -LAT shows several new features in high energy gamma-rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last 6 years, it has been Swift that has provided the robust dataset of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT detected GRBs and the well studied, fainter, less energetic GRBs detected by Swift -BAT is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and Fermi -GBM, and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties, in order to better understand the nature of the special characteristics of the LAT bursts.

  1. FERMI AND SWIFT GAMMA-RAY BURST AFTERGLOW POPULATION STUDIES

    SciTech Connect

    Racusin, J. L.; Donato, D.; Gehrels, N.; McEnery, J.; Sakamoto, T.; Troja, E.; Vasileiou, V.; Oates, S. R.; De Pasquale, M.; Schady, P.; Burrows, D. N.; Koch, S.; Roming, P.; Swenson, C.; Piran, T.; Wanderman, D.; Virgili, F.; Zhang, B.

    2011-09-10

    The new and extreme population of gamma-ray bursts (GRBs) detected by the Fermi Large Area Telescope (LAT) shows several new features in high-energy gamma rays that are providing interesting and unexpected clues into GRB prompt and afterglow emission mechanisms. Over the last six years, it has been Swift that has provided the robust data set of UV/optical and X-ray afterglow observations that opened many windows into components of GRB emission structure. The relationship between the LAT-detected GRBs and the well-studied, fainter, and less energetic GRBs detected by the Swift Burst Alert Telescope is only beginning to be explored by multi-wavelength studies. We explore the large sample of GRBs detected by BAT only, BAT and the Fermi Gamma-ray Burst Monitor (GBM), and GBM and LAT, focusing on these samples separately in order to search for statistically significant differences between the populations, using only those GRBs with measured redshifts in order to physically characterize these objects. We disentangle which differences are instrumental selection effects versus intrinsic properties in order to better understand the nature of the special characteristics of the LAT bursts.

  2. IDENTIFICATION AND PROPERTIES OF THE PHOTOSPHERIC EMISSION IN GRB090902B

    SciTech Connect

    Ryde, F.; McGlynn, S.; Lundman, C.; Battelino, M.; Axelsson, M.; Larsson, S.; Larsson, J.; Zhang, B. B.; Zhang, B.; Pe'er, A.; Bissaldi, E.; McBreen, S.; Bregeon, J.; Briggs, M. S.; Guiriec, S.; Chiang, J.; De Palma, F.; Longo, F.; Omodei, N.; Petrosian, V.

    2010-02-01

    The Fermi Gamma-ray Space Telescope observed 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 {approx}290 keV. We 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 {sub ph} = (1.1 {+-} 0.3) x 10{sup 12} Y {sup 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 {gamma} = 750 Y {sup 1/4}. Here, Y is the ratio between the total fireball energy and the energy emitted in the gamma rays. 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 interpret the broadband emission as synchrotron emission at R {approx} 4 x 10{sup 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.

  3. Identification and Properties of the Photospheric Emission in GRB090902B

    NASA Astrophysics Data System (ADS)

    Ryde, F.; Axelsson, M.; Zhang, B. B.; McGlynn, S.; Pe'er, A.; Lundman, C.; Larsson, S.; Battelino, M.; Zhang, B.; Bissaldi, E.; Bregeon, J.; Briggs, M. S.; Chiang, J.; de Palma, F.; Guiriec, S.; Larsson, J.; Longo, F.; McBreen, S.; Omodei, N.; Petrosian, V.; Preece, R.; van der Horst, A. J.

    2010-02-01

    The Fermi Gamma-ray Space Telescope observed 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. We 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) × 1012 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. 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 interpret the broadband emission as synchrotron emission at R ~ 4 × 1015 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.

  4. The X-ray afterglows of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Watson, D.

    2014-07-01

    Gamma-ray bursts are renowned for being the brightest explosions since the Big Bang. They are extremely useful probes with which to study the cosmos, primarily because of their bright afterglows. While the afterglow is panchromatic, the X-ray afterglow has proved extremely useful: the first localisations of both short and long-duration GRBs were made via their X-ray afterglows, an X-ray afterglow is associated with almost every burst, and spectroscopy of the X-ray afterglow informs us of the material close to the GRB as well as providing an unobscured measurement of the afterglow flux for virtually every GRB. We now have an incredibly rich database of ten years worth of GRBs and their afterglows from the Swift satellite, where its rapid autonomous repointing has allowed its X-Ray Telescope to be on target only minutes after the GRB. Here I will review what we have learnt from the X-ray afterglows of GRBs and describe some exciting recent results.

  5. PROSPECTS FOR GRB SCIENCE WITH THE FERMI LARGE AREA TELESCOPE

    SciTech Connect

    Band, D. L.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Battelino, M.; Bissaldi, E.; Bogaert, G.; Chiang, J.; Do Couto e Silva, E.; Cohen-Tanugi, J.; Cutini, S.; De Palma, F.; Dingus, B. L.; Fishman, G.

    2009-08-20

    The Large Area Telescope (LAT) instrument on the Fermi mission will reveal the rich spectral and temporal gamma-ray burst (GRB) phenomena in the >100 MeV band. The synergy with Fermi's Gamma-ray Burst Monitor detectors will link these observations to those in the well explored 10-1000 keV range; the addition of the >100 MeV band observations will resolve theoretical uncertainties about burst emission in both the prompt and afterglow phases. Trigger algorithms will be applied to the LAT data both onboard the spacecraft and on the ground. The sensitivity of these triggers will differ because of the available computing resources onboard and on the ground. Here we present the LAT's burst detection methodologies and the instrument's GRB capabilities.

  6. Extinction curves of GRB environment with the X-shooter spectrograph

    NASA Astrophysics Data System (ADS)

    Gomboc, Andreja; Japelj, Jure; Covino, Stefano

    2015-08-01

    Gamma Ray Bursts (GRBs) can be used as a powerful tool to study galactic environments at different epochs of the Universe’s evolution, thanks to their bright afterglow emission ranging from X-rays to optical and radio wavebands. Important aspect of the environment is dust, which plays a central role in the astrophysical processes of interstellar medium and in the formation of stars. GRBs can be a unique probe of dust at cosmological distances, where its origin and properties are still poorly known.By using a sample of GRB afterglow spectra observed with the VLT/X-shooter spectrograph we studied the rest-frame extinction in GRB lines-of-sight by modelling the broadband near-infrared to X-ray afterglow spectral energy distributions. We will present our results on the rest-frame extinction of our sample, and illustrate that the spectroscopic data, thanks to a combination of excellent resolution and coverage of the blue part of the spectral energy distributions, are more successful than photometric measurements in constraining the extinction curves and therefore the dust properties in GRB hosts.

  7. Timing Analysis of Unusual GRB 090709A Observed by Suzaku Wide-band All sky Monitor

    SciTech Connect

    Iwakiri, W.; Terada, Y.; Tashiro, M. S.; Ohno, M.; Nakagawa, Y. E.; Yoshida, A.; Yamaoka, K.; Makishima, K.

    2010-10-15

    A result of a joint timing analysis is presented for prompt emission of long-duration (T90 = 81 s) GRB 090709A with Swift Burst Alert Telescope (Swift/BAT), Suzaku Wide-band All-sky Monitor (Suzaku/WAM) and Konus-Wind over an energy range from 15 keV to 5 MeV. It was reported that multi-peaked GRB 090709A exhibited a possible periodic behavior with a period of about 8 s which is comparable to typical time scale of soft gamma-ray repeaters. However, the periodicity is still marginal in detailed analysis with Swift/BAT and GRB090709A exhibited a typical afterglow[1][2]. To investigate significance of the periodicity more quantitatively, we performed a detailed timing analysis on all the lightcurves obtained with Suzaku/WAM, Swift/BAT, and Konus-Wind evaluating their underlying trend, red noise and white noise.

  8. A HOT COCOON IN THE ULTRALONG GRB 130925A: HINTS OF A POPIII-LIKE PROGENITOR IN A LOW-DENSITY WIND ENVIRONMENT

    SciTech Connect

    Piro, Luigi; Troja, Eleonora; Kidd, Lauren A.; Ghisellini, Gabriele; Ricci, Roberto; Bannister, Keith; Fiore, Fabrizio; Piranomonte, Silvia; Wieringa, Mark H.

    2014-08-01

    GRB 130925A is a peculiar event characterized by an extremely long gamma-ray duration (≈7 ks), as well as dramatic flaring in the X-rays for ≈20 ks. After this period, its X-ray afterglow shows an atypical soft spectrum with photon index Γ ∼ 4, as observed by Swift and Chandra, until ≈10{sup 7} s, when XMM-Newton observations uncover a harder spectral shape with Γ ∼ 2.5, commonly observed in gamma-ray burst (GRB) afterglows. We find that two distinct emission components are needed to explain the X-ray observations: a thermal component, which dominates the X-ray emission for several weeks, and a non-thermal component, consistent with a typical afterglow. A forward shock model well describes the broadband (from radio to X-rays) afterglow spectrum at various epochs. It requires an ambient medium with a very low-density wind profile, consistent with that expected from a low-metallicity blue supergiant (BSG). The thermal component has a remarkably constant size and a total energy consistent with those expected by a hot cocoon surrounding the relativistic jet. We argue that the features observed in this GRB (its ultralong duration, the thermal cocoon, and the low-density wind environment) are associated with a low metallicity BSG progenitor and, thus, should characterize the class of ultralong GRBs.

  9. 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. PMID:17363631

  10. GRB follow-up with BOOTES Optical Chapter 5: The Swift Era

    SciTech Connect

    Jelinek, Martin; Castro-Tirado, Alberto J.; Vitek, Stanislav; Ugarte Postigo, Antonio de; Kubanek, Petr; Hudec, Rene

    2006-05-19

    BOOTES is a robotic system, whose primary aim is to observe gamma-ray burst prompt emission. Since 1998 BOOTES has provided follow-up observations for more than 70 GRBs; the most important results obtained so far are the detection of an OT in the short/hard GRB 000313 error box, the detection of several optical after-glow for long/soft GRBs and the non-detection of optical emission simultaneous to the high energy emission for several GRBs (both long/soft and short/hard events). During the time of operation we have got triggers from CGRO/BATSE, BeppoSAX, HETE-2, INTEGRAL and Swift. Here we present our early detections of GRB optical emission using the 30 cm Bootes-1B telescope in the R.V and I-bands since the launch of Swift.

  11. GRB 140206A: the most distant polarized gamma-ray burst

    NASA Astrophysics Data System (ADS)

    Götz, D.; Laurent, P.; Antier, S.; Covino, S.; D'Avanzo, P.; D'Elia, V.; Melandri, A.

    2014-11-01

    The nature of the prompt gamma-ray emission of gamma-ray bursts (GRBs) is still far from being completely elucidated. The measure of linear polarization is a powerful tool that can be used to put further constraints on the content and magnetization of the GRB relativistic outflows, as well as on the radiation processes at work. To date, only a handful of polarization measurements are available for the prompt emission of GRBs. Here we present the analysis of the prompt emission of GRB 140206A, obtained with INTEGRAL/IBIS, Swift/BAT, and Fermi/GBM. Using INTEGRAL/IBIS as a Compton polarimeter, we were able to constrain the linear polarization level of the second peak of this GRB as being larger than 28 per cent at 90 per cent c.l. We also present the GRB afterglow optical spectroscopy obtained at the Telescopio Nazionale Galileo, which allowed us to measure the distance of this GRB, z = 2.739. This distance value together with the polarization measure obtained with IBIS allowed us to derive the deepest and most reliable limit to date (ξ < 1 × 10-16) on the possibility of Lorentz invariance violation, measured through the vacuum birefringence effect on a cosmological source.

  12. POPULATION III GAMMA-RAY BURST AFTERGLOWS: CONSTRAINTS ON STELLAR MASSES AND EXTERNAL MEDIUM DENSITIES

    SciTech Connect

    Toma, Kenji; Meszaros, Peter; Sakamoto, Takanori E-mail: nnp@astro.psu.edu

    2011-04-20

    Population (Pop.) III stars are theoretically expected to be prominent around redshifts z {approx} 20, consisting of mainly very massive stars with M{sub *} {approx}> 100 M{sub sun}, though there is no direct observational evidence for these objects. They may produce collapsar gamma-ray bursts (GRBs), with jets driven by magnetohydrodynamic processes, whose total isotropic-equivalent energy could be as high as E{sub iso} {approx}> 10{sup 57} erg over a cosmological-rest-frame duration of t{sub d} {approx}> 10{sup 4} s, depending on the progenitor mass. Here, we calculate the afterglow spectra of such Pop. III GRBs based on the standard external shock model and show that they will be detectable with the Swift Burst Alert Telescope (BAT)/XRT and Fermi Large Area Telescope (LAT) instruments. We find that in some cases a spectral break due to electron-positron pair creation will be observable in the LAT energy range, which can put constraints on the ambient density of the pre-collapse Pop. III star. Thus, high-redshift GRB afterglow observations could be unique and powerful probes of the properties of Pop. III stars and their environments. We examine the trigger threshold of the BAT instrument in detail, focusing on the image trigger system, and show that the prompt emission of Pop. III GRBs could also be detected by BAT. Finally we briefly show that the late-time radio afterglows of Pop. III GRBs for typical parameters, despite the large distances, can be very bright: {approx_equal} 140 mJy at 1 GHz, which may lead to a constraint on the Pop. III GRB rate from the current radio survey data, and {approx_equal} 2.4 mJy at 70 MHz, which implies that Pop. III GRB radio afterglows could be interesting background source candidates for 21 cm absorption line detections.

  13. FERMI OBSERVATIONS OF HIGH-ENERGY GAMMA-RAY EMISSION FROM GRB 080825C

    SciTech Connect

    Abdo, A. A.; Ackermann, M.; Bechtol, K.; Berenji, B.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bhat, P. N.; Bissaldi, E.; Bonamente, E. E-mail: j.granot@herts.ac.u

    2009-12-10

    The Fermi Gamma-ray Space Telescope has opened a new high-energy window in the study of gamma-ray bursts (GRBs). Here 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. We also present some theoretical interpretation of GRB 080825C observations as well as some common features observed in other LAT GRBs.

  14. Fermi Observations of High-energy Gamma-ray Emission from GRB 080825C

    NASA Astrophysics Data System (ADS)

    Abdo, A. A.; Ackermann, M.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Band, D. L.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bhat, P. N.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Burnett, T. H.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Casandjian, J. M.; Cecchi, C.; Chaplin, V.; Chekhtman, A.; 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.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Gibby, L.; Giebels, B.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Goldstein, A.; Granot, J.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Hanabata, Y.; Harding, A. K.; Hayashida, M.; Hays, E.; Hughes, R. E.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Knödlseder, J.; Kocevski, D.; Komin, N.; Kouveliotou, C.; Kuehn, F.; Kuss, M.; Latronico, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McBreen, S.; McEnery, J. E.; McGlynn, S.; Meegan, C.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; 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.; Piron, F.; Porter, T. A.; Preece, R.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; 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.; Sgrò, C.; Siskind, E. J.; Smith, D. A.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Tibaldo, L.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; 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.; Ylinen, T.; Ziegler, M.

    2009-12-01

    The Fermi Gamma-ray Space Telescope has opened a new high-energy window in the study of gamma-ray bursts (GRBs). Here 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. We also present some theoretical interpretation of GRB 080825C observations as well as some common features observed in other LAT GRBs.

  15. The unusual behaviour of GRB 141221A

    NASA Astrophysics Data System (ADS)

    Bardho, Onelda; Boer, Michel; Klotz, Alain; Gendre, Bruce; Amati, Lorenzo; Rossi, Andrea; Haislip, Joshua; Palazzi, Eliana; Reichart, Dan

    2016-07-01

    We investigate the behaviour of GRB 141221A from infrared to soft gamma-ray bands in the light of standard model. The optical light curve of the afterglow presents an unusual phase. We discuss the spectral energy distribution by considering three different hypotheses: thermal component, ISM and wind medium. In each of them, this burst challenges the GRB models, even the stellar nature of progenitors.

  16. Chandra Observations of the X-ray Environs of SN 1998bw/GRB 980425

    NASA Technical Reports Server (NTRS)

    Kouveliotou, C.; Woosley, S. E.; Patel, S. K.; Levan, A.; Blandford, R.; Ramirez-Ruiz, E.; Wijers, R. A. M. J.; Weisskopf, M. C.; Tennant, A.; Pian, E.

    2004-01-01

    We report X-ray studies of the environs of SN 1998bw and GRB 980425 using the Chandra X-Ray Observatory 1281 days after the gamma-ray burst (GRB). Eight X-ray point sources were localized, three and five each in the original error boxes, S1 and S2, assigned for variable X-ray counteparts to the GRB by BeppoSAX. The sum of the discrete X-ray sources plus continuous emission in S2 observed by Chandra 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 therefore 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 S 1, S 1 a, 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. 1400 days, is obtained by assuming that the burst and supernova were coincident at 35.6 Mpc. When this X-ray light curve is compared with those of the X-ray af "erglows" of ordinary GRBs, X-ray flashes, and ordinary supernovae, evidence emerges for at least two classes of light curves, perhaps bounding a continuum. By 3-10 yr, 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 1998 bw aid GRB 980425 took place in the same object.One possible explanation for the two classes is that a (nearly) standard GRB was observed at different angles, in which case X-ray afterglows with intermediate luminosities should eventually be discovered. Finally, we comment on the contribution of GRB afterglows to the ultraluminous X-ray source population.

  17. 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.; Afonso, P. M. J.; Clemens, C.; Elliott, J.; Nicuesa Guelbenzu, A.; Olivares, F.; Rau, A.

    2011-01-01

    Using high-quality, broad-band afterglow data for GRB 091127, we investigate the validity of the synchrotron fireball model for gamma-ray bursts, 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' t' i' z' JH filters and the XRT onboard the Swift satellite in the 0.3 to 10 keY 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/NlR 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 (V(sub c) varies as t(sup -1.2) is not consistent with the predictions of the standard model, wherein V(sub c) varies as t(sup -05) 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 epsilon(sub Beta). This conclusion provides further evidence that the standard fireball model is too simplistic, and time-dependent micro

  18. A LEPTONIC-HADRONIC MODEL FOR THE AFTERGLOW OF GAMMA-RAY BURST 090510

    SciTech Connect

    Razzaque, Soebur

    2010-11-20

    We model multiwavelength afterglow data from the short gamma-ray burst (GRB) 090510 using a combined leptonic-hadronic model of synchrotron radiation from an adiabatic blast wave. High-energy, {approx_gt}100 MeV, emission in our model is dominated by proton-synchrotron radiation, while electron-synchrotron radiation dominates in the X-ray and ultraviolet wavelengths. The collimation-corrected GRB energy, depending on the jet-break time, in this model could be as low as 3 x 10{sup 51} erg but two orders of magnitude larger than the absolute {gamma}-ray energy. We also calculated the opacities for electron-positron pair production by {gamma}-rays and found that TeV {gamma}-rays from proton-synchrotron radiation can escape the blast wave at early time, and their detection can provide evidence of a hadronic emission component dominating at high energies.

  19. The high-redshift gamma-ray burst GRB 140515A

    SciTech Connect

    Melandri, A.; Bernardini, M. G.; D'Avanzo, P. D.; Sanchez-Ramirez, R.; Nappo, F.; Nava, L.; Japelj, J.; de Ugarte Postigo, A.; Oates, S.; Campana, S.; Covino, S.; D'Elia, V.; Ghirlanda, G.; Gafton, E.; Ghisellini, G.; Gnedin, N.; Goldoni, P.; Gorosabel, J.; Libbrecht, T.; Malesani, D.; Salvaterra, R.; Thone, C. C.; Vergani, S. D.; Xu, D.; Tagliaferri, G.

    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 xHI ≤ 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded in 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.

  20. The high-redshift gamma-ray burst GRB 140515A

    DOE PAGESBeta

    Melandri, A.; Bernardini, M. G.; D'Avanzo, P. D.; Sanchez-Ramirez, R.; Nappo, F.; Nava, L.; Japelj, J.; de Ugarte Postigo, A.; Oates, S.; Campana, S.; et al

    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 xHI ≤ 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded in amore » 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

  1. Observations of GRB 990123 by the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Briggs, M. S.; Band, D. L.; Kippen, R. M.; Preece, R. D.; Kouveliotou, C.; vanParadijs, J.; Share, G. H.; Murphy, R. J.; Matz, S. M.; Connors, A.

    1999-01-01

    GRB 990123 was the first burst from which simultaneous optical, X-ray, and gamma-ray emission was detected; its afterglow has been followed by an extensive set of radio, optical, and X-ray observations. We have studied the gamma-ray burst itself as observed by the Compton Gamma Ray Observatory detectors. We find that gamma-ray fluxes are not correlated with the simultaneous optical observations and that the gamma-ray spectra cannot be extrapolated simply to the optical fluxes. The burst is well fitted by the standard four-parameter GRB function, with the exception that excess emission compared with this function is observed below approx. 15 keV during some time intervals. The burst is characterized by the typical hard-to-soft and hardness-intensity correlation spectral evolution patterns. The energy of the peak of the vf (sub v), spectrum, E (sub p), reaches an unusually high value during the first intensity spike, 1470 plus or minus 110 keV, and then falls to approx. 300 keV during the tail of the burst. The high-energy spectrum above approx. 1 MeV is consistent with a power law with a photon index of about -3. By fluence, GRB 990123 is brighter than all but 0.4% of the GRBs observed with BATSE (Burst and Transient Source Experiment), clearly placing it on the -3/2 power-law portion of the intensity distribution. However, the redshift measured for the afterglow is inconsistent with the Euclidean interpretation of the -3/2 power law. Using the redshift value of greater than or equal to 1.61 and assuming isotropic emission, the gamma-ray energy exceeds 10 (exp 54) ergs.

  2. Simulation Study Of Early Afterglows Observed With Swift

    NASA Astrophysics Data System (ADS)

    Nishikawa, Ken-Ichi; Hededal, C.; Hardee, P.; Mizuno, Y.; Fishman, G. J.

    2006-09-01

    A 3-D relativistic particle-in-cell code has been used to simulate the dynamics of forward and reverse shocks with thin and thick shells within the parameter constraints provided by present Swift observations and the present models of GRB emission. Our 3-D RPIC simulations have provided the dynamics of collisionless shocks in electron-ion and electron-positron plasmas with and without initial ambient magnetic fields and revealed the importance of ``jitter radiation'' with prompt and afterglow spectra due to the inhomogeneous magnetic fields generated by the Weibel instability. It is different from synchrotron radiation, which is usually assumed to be the dominant radiation process. We have investigated gamma-ray burst emissions from prompt, early, and late afterglows considering microscopic processes. Based on our previous investigation of the Weibel instability for each stage of evolution of ejecta propagating in the ISM, we have incorporated the plasma conditions (relativistic jets) with the density and composition of the plasmas, the magnetic field strength ($\\sigma$-values (the ratio of the electromagnetic energy flux to the particle energy flux)) and its direction, and the Lorentz factor for the different stages in prompt and afterglows. Systematic simulation studies of the relativistic collisionless shocks, associated particle acceleration, magnetic field generation and self-consistent radiation provide insight into undetermined issues in prompt and afterglows observed by Swift. Self-consistently calculated lightcurves, spectra, spectral evolutions, and polarization as function of viewing angle will be done to light a shed on recent new observations by Swift, in particular, X-ray flares, early steep decay, and shallow decay.

  3. Energies of GRB blast waves and prompt efficiencies as implied by modelling of X-ray and GeV afterglows

    NASA Astrophysics Data System (ADS)

    Beniamini, Paz; Nava, Lara; Duran, Rodolfo Barniol; Piran, Tsvi

    2015-11-01

    We consider a sample of 10 gamma-ray bursts with long-lasting ( ≳ 102 s) emission detected by Fermi/Large Area Telescope and for which X-ray data around 1 d are also available. We assume that both the X-rays and the GeV emission are produced by electrons accelerated at the external forward shock, and show that the X-ray and the GeV fluxes lead to very different estimates of the initial kinetic energy of the blast wave. The energy estimated from GeV is on average ˜50 times larger than the one estimated from X-rays. We model the data (accounting also for optical detections around 1 d, if available) to unveil the reason for this discrepancy and find that good modelling within the forward shock model is always possible and leads to two possibilities: (i) either the X-ray emitting electrons (unlike the GeV emitting electrons) are in the slow-cooling regime or (ii) the X-ray synchrotron flux is strongly suppressed by Compton cooling, whereas, due to the Klein-Nishina suppression, this effect is much smaller at GeV energies. In both cases the X-ray flux is no longer a robust proxy for the blast wave kinetic energy. On average, both cases require weak magnetic fields (10-6 ≲ ɛB ≲ 10-3) and relatively large isotropic kinetic blast wave energies 10^{53} erg<{E}_{0,kin}<10^{55} erg corresponding to large lower limits on the collimated energies, in the range 10^{52} erg<{E}_{θ ,kin}<5× 10^{52} erg for an ISM (interstellar medium) environment with n ˜ 1 cm-3 and 10^{52} erg<{E}_{θ ,kin}<10^{53} erg for a wind environment with A* ˜ 1. These energies are larger than those estimated from the X-ray flux alone, and imply smaller inferred values of the prompt efficiency mechanism, reducing the efficiency requirements on the still uncertain mechanism responsible for prompt emission.

  4. SWIFT Discovery of Gamma-ray Bursts without Jet Break Feature in their X-ray Afterglows

    NASA Technical Reports Server (NTRS)

    Sato, G.; Yamazaki, R.; Sakamoto, T.; Takahashi, T; Nakazawa, K.; Nakamura, T.; Toma, K.; Hullinger, D.; Tashiro, M.; Parsons, A. M.; Krimm, H. A.; Barthelmy, S. D.; Gehrels, N.; Burrows, D. N.; O'Brien, P. T.; Osborne, J. P.; Chincarini, G.; Lamb, D. Q.

    2007-01-01

    We analyze Swift gamma-ray bursts (GRBs) and X-ray afterglows for three GRBs with spectroscopic redshift determinations - GRB 050401, XRF 050416a, and GRB 050525a. We find that the relation between spectral peak energy and isotropic energy of prompt emissions (the Amati relation) is consistent with that for the bursts observed in pre-Swift era. However, we find that the X-ray afterglow lightcurves, which extend up to 10 - 70 days, show no sign of the jet break that is expected in the standard framework of collimated outflows. We do so by showing that none of the X-ray afterglow lightcurves in our sample satisfies the relation between the spectral and temporal indices that is predicted for the phase after jet break. The jet break time can be predicted by inverting the tight empirical relation between the peak energy of the spectrum and the collimation-corrected energy of the prompt emission (the Ghirlanda relation). We find that there are no temporal breaks within the predicted time intervals in X-ray band. This requires either that the Ghirlanda relation has a larger scatter than previously thought, that the temporal break in X-rays is masked by some additional source of X-ray emission, or that it does not happen because of some unknown reason.

  5. Understanding Grb Physics With Multi-Wavelength Data

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    /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.

  6. GRB 050717: A Long, Short-Lag Burst Observed by Swift and Konus

    SciTech Connect

    Krimm, H. A.; Hurkett, C.; Osborne, J. P.; Pal'shin, V.; Golenetskii, S.; Norris, J. P.; Barthelmy, S. D.; Gehrels, N.; Parsons, A. M.; Zhang, B.; Burrows, D. N.; Perri, M.

    2006-05-19

    The long burst GRB 050717 was observed simultaneously by the Burst Alert Telescope (BAT) on Swift and the Konus instrument on Wind. Significant hard to soft spectral evolution was seen. Early gamma-ray and X-ray emission was detected by both BAT and the X-Ray Telescope (XRT) on Swift. The XRT continued to observe the burst for 7.1 days and detect it for 1.4 days. The X-ray light curve showed a classic decay pattern including evidence of the onset of the external shock emission at {approx} 45 s after the trigger; the afterglow was too faint for a jet break to be detected. No optical, infrared or ultraviolet counterpart was discovered despite deep searches within 14 hours of the burst. The spectral lag for GRB 050717 was determined to be 2.5 {+-} 2.6 ms, consistent with zero and unusually short for a long burst. This lag measurement suggests that this burst has a high intrinsic luminosity and hence is at high redshift (z > 2.7). GRB 050717 provides a good example of classic prompt and afterglow behavior for a gamma-ray burst.

  7. High-energy gamma-rays from GRB X-ray flares

    SciTech Connect

    Wang, X. Y.; Li, Z.; Meszaros, P.

    2007-07-12

    The recent detection of X-ray flares during the afterglow phase of gamma-ray bursts (GRBs) suggests an inner-engine origin, at radii inside the forward shock. There must be inverse Compton (IC) emission arising from such flare photons scattered by forward shock afterglow electrons when they are passing through the forward shock. We find that this IC emission produces high energy gamma-ray flares, which may be detected by AGILE, GLAST and ground-based TeV telescopes. The anisotropic IC scattering between flare photons and forward shock electrons does not affect the total IC component intensity, but cause a time delay of the IC component peak relative to the flare peak. We speculate that this IC component may already have been detected by EGRET from a very strong burst--GRB940217. Future observations by GLAST may help to distinguish whether X-ray flares originate from late central engine activity or from external shocks.

  8. GRB 140606B/iPTF14bfu: detection of shock-breakout emission from a cosmological γ-ray burst?

    NASA Astrophysics Data System (ADS)

    Cano, Zach; de Ugarte Postigo, A.; Perley, D.; Krühler, T.; Margutti, R.; Friis, M.; Malesani, D.; Jakobsson, P.; Fynbo, J. P. U.; Gorosabel, J.; Hjorth, J.; Sánchez-Ramírez, R.; Schulze, S.; Tanvir, N. R.; Thöne, C. C.; Xu, D.

    2015-09-01

    We present optical and near-infrared photometry of GRB 140606B (z = 0.384), and optical photometry and spectroscopy of its associated supernova (SN). The results of our modelling indicate that the bolometric properties of the SN (MNi = 0.4 ± 0.2 M⊙, Mej = 5 ± 2 M⊙, and EK = 2 ± 1 × 1052 erg) are fully consistent with the statistical averages determined for other γ-ray burst (GRB)-SNe. However, in terms of its γ-ray emission, GRB 140606B is an outlier of the Amati relation, and occupies the same region as low luminosity (ll) and short GRBs. The γ-ray emission in llGRBs is thought to arise in some or all events from a shock breakout (SBO), rather than from a jet. The measured peak photon energy (Ep ≈ 800 keV) is close to that expected for γ-rays created by an SBO (≳ 1 MeV). Moreover, based on its position in the MV, p-Liso, γ plane and the EK-Γβ plane, GRB 140606B has properties similar to both SBO-GRBs and jetted-GRBs. Additionally, we searched for correlations between the isotropic γ-ray emission and the bolometric properties of a sample of GRB-SNe, finding that no statistically significant correlation is present. The average kinetic energy of the sample is bar{E}_K = 2.1× 10^{52} erg. All of the GRB-SNe in our sample, with the exception of SN 2006aj, are within this range, which has implications for the total energy budget available to power both the relativistic and non-relativistic components in a GRB-SN event.

  9. Chandra Observations of the X-ray Environs of SN 1998bw/GRB 980425

    NASA Technical Reports Server (NTRS)

    Kouveliotou, C.; Woosley, S. E.; Patel, S. K.; Levan, A.; Blandford, R.; Ramirez-Ruiz, E.; Wijers, R. A. M. J.; Weisskopf, M. C.; Tennant, A.; Pian, E.

    2004-01-01

    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 five 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 therefore 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, Sla, 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 approximately 1300 days, is obtained by assuming the burst and supernova were coincident at 35.6 Mpc. When this X-ray iight 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.

  10. Early-Time Observations of GRBs afterglow with 2-m Robotic Telescopes

    SciTech Connect

    Melandri, A.; Mundell, C. G.; Steele, I. A.; Carter, D.; Kobayashi, S.; Bersier, D.; Bode, M. F.; Mottram, C. J.; Smith, R. J.; Gomboc, A.; Guidorzi, C.; Monfardini, A.

    2007-08-21

    In the era of rapid and accurate localisation of Gamma Ray Bursts by the Swift satellite, high quality early time multi-wavelength light curves, obtained by space and ground-based robotic telescopes, have shown that the standard 'smooth temporal power law decays' typical of late-time afterglow emission can be substantially modified at early times by e.g. energy injection from long-lived central engines, and/or interactions between the ejecta and clumps in the surrounding circumburst medium. Well-sampled optical light curves (covering a wide range in time, brightness and redshift) together with early-time polarimetry provide a powerful probe of the physics of GRBs, their ejecta and their environments. Here we summarise the GRB followup programme being conducted on a network of the world's three largest robotic telescopes that aims to obtain early-time multicolour photometric and polarimetric measurements crucial for the understanding of GRB physics.

  11. iPTF14yb: The First Discovery of a Gamma-Ray Burst Afterglow Independent of a High-Energy Trigger

    NASA Technical Reports Server (NTRS)

    Cenko, S. Bradley; Urban, Alex L.; Perley, Daniel A.; Horesh, Assaf; Corsi, Alessandra; Fox, Derek B.; Cao, Yi; Kasliwal, Mansi M.; Lien, Amy; Arcavi, Iair; Bloom, Joshua S.; Butler, Nat R.; Cucchiara, Antonino; De Diego, Jose A.; Filippenko, Alexei V.; Gal-Yam, Avishay; Gehrels, Neil; Georgiev, Leonid; Gonzalez, J. Jesus; Graham, John F.; Greiner, Jochen; Kann, D. Alexander; Klein, Christopher R.; Knust, Fabian; Kutyrev, Alexander

    2015-01-01

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous (Mr >> -27.8 mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based on probabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow of the long-duration gamma-ray burst GRB 140226A. This marks the first unambiguous discovery of a GRB afterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate of iPTF14yb-like sources (i.e., cosmologically distant relativistic explosions) based on iPTF observations, inferring an all-sky value of Rrel = 610/yr (68% confidence interval of 110-2000/yr). Our derived rate is consistent (within the large uncertainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, we briefly discuss the implications of the nondetection to date of bona fide "orphan" afterglows (i.e., those lacking detectable high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.

  12. iPTF14yb: The First Discovery of a Gamma-Ray Burst Afterglow Independent of a High-energy Trigger

    NASA Astrophysics Data System (ADS)

    Cenko, S. Bradley; Urban, Alex L.; Perley, Daniel A.; Horesh, Assaf; Corsi, Alessandra; Fox, Derek B.; Cao, Yi; Kasliwal, Mansi M.; Lien, Amy; Arcavi, Iair; Bloom, Joshua S.; Butler, Nat R.; Cucchiara, Antonino; de Diego, José A.; Filippenko, Alexei V.; Gal-Yam, Avishay; Gehrels, Neil; Georgiev, Leonid; Jesús González, J.; Graham, John F.; Greiner, Jochen; Kann, D. Alexander; Klein, Christopher R.; Knust, Fabian; Kulkarni, S. R.; Kutyrev, Alexander; Laher, Russ; Lee, William H.; Nugent, Peter E.; Prochaska, J. Xavier; Ramirez-Ruiz, Enrico; Richer, Michael G.; Rubin, Adam; Urata, Yuji; Varela, Karla; Watson, Alan M.; Wozniak, Przemek R.

    2015-04-01

    We report here the discovery by the Intermediate Palomar Transient Factory (iPTF) of iPTF14yb, a luminous ({{M}r}≈ -27.8 mag), cosmological (redshift 1.9733), rapidly fading optical transient. We demonstrate, based on probabilistic arguments and a comparison with the broader population, that iPTF14yb is the optical afterglow of the long-duration gamma-ray burst GRB 140226A. This marks the first unambiguous discovery of a GRB afterglow prior to (and thus entirely independent of) an associated high-energy trigger. We estimate the rate of iPTF14yb-like sources (i.e., cosmologically distant relativistic explosions) based on iPTF observations, inferring an all-sky value of {{\\Re }rel}=610 yr-1 (68% confidence interval of 110-2000 yr-1). Our derived rate is consistent (within the large uncertainty) with the all-sky rate of on-axis GRBs derived by the Swift satellite. Finally, we briefly discuss the implications of the nondetection to date of bona fide “orphan” afterglows (i.e., those lacking detectable high-energy emission) on GRB beaming and the degree of baryon loading in these relativistic jets.

  13. A Reverse Shock in GRB 130427A

    NASA Astrophysics Data System (ADS)

    Laskar, Tanmoy; Berger, Edo; Zauderer, B. Ashley; Margutti, Raffaella; Soderberg, Alicia Margarita; Lunnan, Ragnhild; Chornock, Ryan

    2014-06-01

    We present extensive radio and millimeter observations of the unusually bright GRB 130427A at z=0.340, spanning 0.67 to 12 days after the burst. Taken in conjunction with detailed multi-band UV, optical, NIR, and X-ray observations we find that the broad-band afterglow emission is composed of distinct reverse shock and forward shock contributions. The reverse shock emission dominates in the radio/millimeter and at <0.1 days in the UV/optical/NIR, while the forward shock emission dominates in the X-rays and at >0.1 days in the UV/optical/NIR. We further find that the optical and X-ray data require a Wind circumburst environment, pointing to a massive star progenitor. Using the combined forward and reverse shock emission we find that the parameters of the burst are an isotropic kinetic energy of E_Kis 2e53 erg, a mass loss rate of Mdo 3e-8 Msun/yr (for a wind velocity of 1,000 km/s), and a Lorentz factor at the deceleration time of Gamma(200s 130. Due to the low density and large isotropic energy, the absence of a jet break to ~15 days places only a weak constraint on the opening angle of theta_j>2.5 deg, and therefore a total energy of E_gamma+E_K>1.2e51 erg, similar to other GRBs. The reverse shock emission is detectable in this burst due to the low circumburst density, which leads to a slow cooling shock. We speculate that this is a required property for the detectability of reverse shocks in the radio and millimeter bands. Following on GRB 130427A as a benchmark event, observations of future GRBs with the exquisite sensitivity of VLA and ALMA, coupled with detailed modeling of the reverse and forward shock contributions will test this hypothesis.

  14. The quest for short GRB radio afterglows

    NASA Astrophysics Data System (ADS)

    Burlon, Davide; Gaensler, Bryan; Murphy, Tara; Hancock, Paul; Bell, Martin; Bannister, Keith; Greiner, Jochen; Klose, Sylvio; Ghirlanda, Giancarlo

    2014-10-01

    Short γ-ray bursts (SGRBs) are the most elusive among GRBs with just a few of them having being studied pan- chromatically. Only three SGRBs have been detected in the radio band in the last 14 years. Radio observations of short GRBs should provide fundamental parameters of the physical process acting in these sources and on the nature of their progenitors. The detection of even a few more short GRBs in the radio band could constrain their true energetics, their radiative efficiency and the density of the environment where they happen (with immediate implications on the nature of their progenitors). The proposed joint radio-optical observations, will allow us for the first time to probe the hydrodynamics of the explosion and the radiation mechanism. We were graded 3.8 for two semesters, but the NAPA was not triggered.

  15. Chandra Observations of the X-ray Environs of SN 1998 bw/GRB 980425

    NASA Technical Reports Server (NTRS)

    Kouveliotou, C.; Woosley, S. E.; Patel, S. K.; Levan, A.; Blanford, R.

    2004-01-01

    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 five 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 therefore 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.

  16. A SUPRAMASSIVE MAGNETAR CENTRAL ENGINE FOR GRB 130603B

    SciTech Connect

    Fan, Yi-Zhong; Jin, Zhi-Ping; Wei, Da-Ming; Yu, Yun-Wei; Xu, Dong; Wu, Xue-Feng; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2013-12-20

    We show that the peculiar early optical emission and, in particular, the X-ray afterglow emission of the short-duration burst GRB 130603B can be explained by continuous energy injection into the blastwave from a supramassive magnetar central engine. The observed energetics and temporal/spectral properties of the late infrared bump (i.e., the {sup k}ilonova{sup )} are also found to be consistent with emission from the ejecta launched during a neutron star (NS)-NS merger and powered by a magnetar central engine. The isotropic-equivalent kinetic energies of both the gamma-ray burst (GRB) blastwave and the kilonova are approximately E{sub k} ∼ 10{sup 51} erg, consistent with being powered by a near-isotropic magnetar wind. However, this relatively small value requires that most of the initial rotational energy of the magnetar (∼a few × 10{sup 52} erg) is carried away by gravitational wave radiation. Our results suggest that (1) the progenitor of GRB 130603B was a NS-NS binary system, the merger product of which would have been a supramassive NS that lasted for about ∼1000 s; (2) the equation of state of the nuclear matter should be stiff enough to allow the survival of a long-lived supramassive NS; thus this suggested that the detection of the bright electromagnetic counterparts of gravitational wave triggers without short GRB associations is promising in the upcoming Advanced LIGO/VIRGO era.

  17. Swift Observations of the X-Ray-Bright GRB 050315

    NASA Astrophysics Data System (ADS)

    Vaughan, S.; Goad, M. R.; Beardmore, A. P.; O'Brien, P. T.; Osborne, J. P.; Page, K. L.; Barthelmy, S. D.; Burrows, D. N.; Campana, S.; Cannizzo, J. K.; Capalbi, M.; Chincarini, G.; Cummings, J. R.; Cusumano, G.; Giommi, P.; Godet, O.; Hill, J. E.; Kobayashi, S.; Kumar, P.; La Parola, V.; Levan, A.; Mangano, V.; Mészáros, P.; Moretti, A.; Morris, D. C.; Nousek, J. A.; Pagani, C.; Palmer, D. M.; Racusin, J. L.; Romano, P.; Tagliaferri, G.; Zhang, B.; Gehrels, N.

    2006-02-01

    This paper discusses Swift observations of the γ-ray burst GRB 050315 (z=1.949) from 80 s to 10 days after the onset of the burst. The X-ray light curve displayed a steep early decay (t-5) for ~200 s and several breaks. However, both the prompt hard X-ray/γ-ray emission (observed by the BAT) and the first ~300 s of X-ray emission (observed by the XRT) can be explained by exponential decays, with similar decay constants. Extrapolating the BAT light curve into the XRT band suggests that the rapidly decaying, early X-ray emission was simply a continuation of the fading prompt emission; this strong similarity between the prompt γ-ray and early X-ray emission may be related to the simple temporal and spectral character of this X-ray-rich GRB. The prompt (BAT) spectrum was steep down to ~15 keV and appeared to continue through the XRT bandpass, implying a low peak energy, inconsistent with the Amati relation. Following the initial steep decline, the X-ray afterglow did not fade for ~1.2×104 s, after which time it decayed with a temporal index of α~0.7, followed by a second break at ~2.5×105 s to a slope of α~2. The apparent ``plateau'' in the X-ray light curve, after the early rapid decay, makes this one of the most extreme examples of the steep-flat-steep X-ray light curves revealed by Swift. If the second afterglow break is identified with a jet break, then the jet opening angle was θ0~5deg, implying Eγ>~1050 ergs.

  18. VizieR Online Data Catalog: List of isolated emission episodes in GRB (Charisi+, 2015)

    NASA Astrophysics Data System (ADS)

    Charisi, M.; Marka, S.; Bartos, I.

    2015-09-01

    We analysed GRB light curves from the three main GRB catalogues: (i) the Gamma-ray Burst Monitor (GBM) on board Fermi Gamma-ray Space Telescope (Meegan et al., 2009ApJ...702..791M), (ii) the Burst Alert Telescope (BAT) on the Swift satellite (Gehrels et al., 2004ApJ...611.1005G), and (iii) the BATSE on board Compton Gamma-Ray Observatory (Fishman et al., 1989, Its Max'91 Workshop 2: Developments in Observations and Theory for Solar Cycle 22. Wingle R. M., Dennis B. R., editors. 1989. p. 96.). We analysed GRBs detected prior to 2014 January 01. The search was confined to long GRBs with nominal duration T90 (T90>2s), where T90 is defined as the time interval during which 90% of the GRB fluence was detected with 5% fluence detected both before and after the interval. Note that T90 was the only property considered in identifying long GRBs. The main reason for this selection is the reduced accuracy of the search for variability shorter than the bin size of the available light curves. Fermi-GBM consists of 12 NaI detectors, sensitive to energies from 8keV to ~1MeV, which cover the entire unocculted sky, along with two BGO detectors sensitive to higher energy photons (~200keV to ~40MeV). The GBM burst catalogue (http://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html) consists of 1276 GRBs (2008 July-2013 December) and the data are publicly available (http://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/) Swift-BAT is a sensitive gamma-ray detector with a wide field of view (1.4sr) designed to provide GRB triggers with accurate localization. During the considered observation period up to the end of 2013 (2004 Decembe-2013 December), Swift had detected 833 GRBs (Sakamoto et al., 2011ApJS..195....2S, Cat. J/ApJS/195/2). The data are retrieved from the public archive (http://swift.gsfc.nasa.gov/archive/) BATSE consisted of eight large NaI area detectors (LADs) covering the energy range of ~25keV to ~2MeV, and was able to observe the entire unobstructed sky. Over its nine

  19. Gamma-Ray Bursts and Afterglows: a Multi-Wavelength Study in the Swift Era

    NASA Astrophysics Data System (ADS)

    Yu, Y. W.

    2010-01-01

    Gamma-ray bursts (GRBs), which are generally followed by long-lasting low-frequency afterglow emission, are short and intense pulses of gamma-rays observed from the sky in arbitrary directions. In order to observe the multi-wavelength emission at the early afterglow phase and even the prompt emission phase, NASA launched the Swift satellite on Nov. 20th 2004. Swift can localize GRBs within about 10 seconds. A brief review on the recent progress in observations and theories in the Swift era is given in Chapter 1. This paper focuses on the features of the early afterglows and the multi-wavelength prompt emission. In Chapters 2 and 3, we try to explain the shallow-decaying X-ray afterglows and X-ray flares, both of which are unaccountable in the standard afterglow model. (1) It is widely accepted that the shallow decay phase indicates a continuous energy injection into the GRB blast wave, and this energy could be released from the central engine after the burst. Based on the knowledge of the evolution of a pulsar wind, we argue that the injected flow interacting with the GRB blast wave is an ultra-relativistic kinetic-energy flow (i.e., wind) rather than pure electromagnetic waves. Therefore, a relativistic wind bubble (RWB) including a pair of shocks will be formed. Our numerical calculations and the fitting results show that the emission from an RWB can well account for the X-ray shallow decay phase. (2) For the X-ray flares that are attributed to some intermediate late activities of the central engine, we analyze the detailed dynamics of late internal shocks which directly produce the flare emission. Comparing the theoretical results with the lower limits of the observational luminosities and the profiles of the flare light curves, we find some constraints on the properties of the pre-collision shells, which are directly determined by the central object. In Chapter 4, we investigate the high-energy afterglow emission during the shallow decay phase in two models, i

  20. The Sub-Energetic GRB 031203 as a Cosmic Analogue to GRB 980425

    SciTech Connect

    Soderberg, A

    2004-08-27

    Over the six years since the discovery of the {gamma}-ray burst GRB 980425, associated with the nearby (distance {approx}40 Mpc) supernova 1998bw, astronomers have fiercely debated the nature of this event. Relative to bursts located at cosmological distances, (redshift, z {approx} 1), GRB 980425 was under-luminous in {gamma}-rays by three orders of magnitude. Radio calorimetry showed the explosion was sub-energetic by a factor of 10. Here, the authors report observations of the radio and X-ray afterglow of the recent z = 0.105 GRB031203 and demonstrate that it too is sub-energetic. The result, when taken together with the low {gamma}-ray luminosity, suggest that GRB031203 is the first cosmic analogue to GRB980425. They find no evidence that this event was a highly collimated explosion viewed off-axis. Like GRB980425, GRB031203 appears to be an intrinsically sub-energetic {gamma}-burst. Such sub-energetic events have faint afterglows. Intensive follow-up of faint bursts with smooth {gamma}-ray light curves (common to both GRBs 031203 and 980425) may enable the authors to reveal their expected large population.

  1. IDENTIFYING THE LOCATION IN THE HOST GALAXY OF THE SHORT GRB 111117A WITH THE CHANDRA SUBARCSECOND POSITION

    SciTech Connect

    Sakamoto, T.; Troja, E.; Aoki, K.; Guiriec, S.; Barthelmy, S. D.; Im, M.; Jeon, Y.; Leloudas, G.; Malesani, D.; De Ugarte Postigo, A.; Andersen, M. I.; Melandri, A.; D'Avanzo, P.; Urata, Y.; Xu, D.; Gorosabel, J.; Sanchez-Ramirez, R.; Briggs, M. S.; Foley, S.; and others

    2013-03-20

    We present our successful Chandra program designed to identify, with subarcsecond accuracy, the X-ray afterglow of the short GRB 111117A, which was discovered by Swift and Fermi. Thanks to our rapid target of opportunity request, Chandra clearly detected the X-ray afterglow, though no optical afterglow was found in deep optical observations. The host galaxy was clearly detected in the optical and near-infrared band, with the best photometric redshift of z=1.31{sub -0.23}{sup +0.46} (90% confidence), making it one of the highest known short gamma-ray burst (GRB) redshifts. Furthermore, we see an offset of 1.0 {+-} 0.2 arcsec, which corresponds to 8.4 {+-} 1.7 kpc, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining subarcsecond X-ray localizations of short GRB afterglows to study GRB environments.

  2. A multi-wavelength study on gamma-ray bursts and their afterglows

    NASA Astrophysics Data System (ADS)

    Zhang, Binbin

    2011-08-01

    During the prompt emission and afterglow phases, GRBs (Gamma-Ray Bursts) release their huge amount of energy not limited in gamma-ray, but in a wide range of muti-wavelengths, from radio band to GeV gamma-rays. Thanks to the recent missions of Swift and Fermi, I was able to use their multi-wavelength observation data of GRBs and study their physical natures. I have processed all the Swift BAT/XRT and Fermi GBM/LAT GRB observation data. Based on the Swift data, I have studied the following comprehensive topics: (1) high-latitude "curvature effect" of early X-ray tails of GRBs Swift XRT afterglow (2) diverse physical origins of shallow decay phase of Swift XRT afterglow. (3) Jet break (in-)consistency in both X-Ray and Optical observations. Based on the Fermi observation data, I focused on the 17 GRBs with Fermi/LAT high-energy emission and found there are three elemental spectral components, namely, a classical "Band" function component, a quasi-thermal component and an extra non-thermal power law component extending to high energies. The detailed behaviors of these three components are extensively studied and their physical origins and corresponding jet properties and emission mechanisms are also discussed.

  3. Jet or Shock Breakout? The Low-Luminosity GRB 060218

    NASA Astrophysics Data System (ADS)

    Irwin, Christopher; Chevalier, Roger

    2016-01-01

    We consider a model for the long-duration, low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The components of our model are: (1) a long-lived (tj ~ 3000 s) central engine and accompanying low-luminosity (Lj ~ 1045 erg s-1), mildly relativistic jet; (2) a low-mass (~ 10-2 Msun) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ~ 0.1) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the prompt nonthermal X-rays and γ-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ~ 1013 cm can explain the early optical peak. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ~ 30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that ultra-long bursts such as GRB 060218 and GRB 100316D may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt high-energy emission from the supernova.

  4. Gamma-Ray Bursts and Afterglows: a Multi-Wavelength Study in the Swift Era

    NASA Astrophysics Data System (ADS)

    Yu, Y. W.

    2010-01-01

    Gamma-ray bursts (GRBs), which are generally followed by long-lasting low-frequency afterglow emission, are short and intense pulses of gamma-rays observed from the sky in arbitrary directions. In order to observe the multi-wavelength emission at the early afterglow phase and even the prompt emission phase, NASA launched the Swift satellite on Nov. 20th 2004. Swift can localize GRBs within about 10 seconds. A brief review on the recent progress in observations and theories in the Swift era is given in Chapter 1. This paper focuses on the features of the early afterglows and the multi-wavelength prompt emission. In Chapters 2 and 3, we try to explain the shallow-decaying X-ray afterglows and X-ray flares, both of which are unaccountable in the standard afterglow model. (1) It is widely accepted that the shallow decay phase indicates a continuous energy injection into the GRB blast wave, and this energy could be released from the central engine after the burst. Based on the knowledge of the evolution of a pulsar wind, we argue that the injected flow interacting with the GRB blast wave is an ultra-relativistic kinetic-energy flow (i.e., wind) rather than pure electromagnetic waves. Therefore, a relativistic wind bubble (RWB) including a pair of shocks will be formed. Our numerical calculations and the fitting results show that the emission from an RWB can well account for the X-ray shallow decay phase. (2) For the X-ray flares that are attributed to some intermediate late activities of the central engine, we analyze the detailed dynamics of late internal shocks which directly produce the flare emission. Comparing the theoretical results with the lower limits of the observational luminosities and the profiles of the flare light curves, we find some constraints on the properties of the pre-collision shells, which are directly determined by the central object. In Chapter 4, we investigate the high-energy afterglow emission during the shallow decay phase in two models, i

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

    SciTech Connect

    Muccino, M.; Ruffini, R.; Bianco, C. L.; Izzo, L.; Penacchioni, A. V.

    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. 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

  6. On the optical and X-ray afterglows of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Dado, S.; Dar, A.; De Rújula, A.

    2002-06-01

    We severely criticize the consuetudinary analysis of the afterglows of gamma-ray bursts (GRBs) in the conical-ejection fireball scenarios. We argue that, instead, recent observations imply that the long-duration GRBs and their afterglows are produced by highly relativistic jets of cannonballs (CBs) emitted in supernova explosions. The CBs are heated by their collision with the supernova shell. The GRB is the boosted surface radiation the CBs emit as they reach the transparent outskirts of the shell. The exiting CBs further decelerate by sweeping up interstellar matter (ISM). The early X-ray afterglow is dominated by thermal bremsstrahlung from the cooling CBs, the optical afterglow by synchrotron radiation from the ISM electrons swept up by the CBs. We show that this model fits simply and remarkably well all the measured optical afterglows of the 15 GRBs with known redshift, including that of GRB 990123, for which unusually prompt data are available. We demonstrate that GRB 980425 was a normal GRB produced by SN1998bw, with standard X-ray and optical afterglows. We find that the very peculiar afterglow of GRB 970508 can be explained if its CBs encountered a significant jump in density as they moved through the ISM. The afterglows of the nearest 8 of the known-redshift GRBs show various degrees of evidence for an association with a supernova akin to SN1998bw. In all other cases such an association, even if present, would have been undetectable with the best current photometric sensitivities. This gives strong support to the proposition that most, maybe all, of the long-duration GRBs are associated with supernovae. Although our emphasis is on optical afterglows, we also provide an excellent description of X-ray afterglows. Figures \\ref{fig228} to \\ref{X1216} are only available in electronic form at http:/www.edpsciences.org

  7. 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

  8. GRB 091024A and the nature of ultra-long gamma-ray bursts

    SciTech Connect

    Virgili, F. J.; Mundell, C. G.; Harrison, R.; Kobayashi, S.; Steele, I. A.; Mottram, C. J.; Clay, N. R.; Pal'shin, V.; Guidorzi, C.; Margutti, R.; Chornock, R.; Melandri, A.; Updike, A. C.; Cenko, S. B.; Tanvir, N. R.; Cucchiara, A.; Levan, A.; Cano, Z.; and others

    2013-11-20

    We present a broadband study of gamma-ray burst (GRB) 091024A within the context of other ultra-long-duration GRBs. An unusually long burst detected by Konus-Wind (KW), Swift, and Fermi, GRB 091024A has prompt emission episodes covering ∼1300 s, accompanied by bright and highly structured optical emission captured by various rapid-response facilities, including the 2 m autonomous robotic Faulkes North and Liverpool Telescopes, KAIT, S-LOTIS, and the Sonoita Research Observatory. We also observed the burst with 8 and 10 m class telescopes and determine the redshift to be z = 1.0924 ± 0.0004. We find no correlation between the optical and γ-ray peaks and interpret the optical light curve as being of external origin, caused by the reverse and forward shock of a highly magnetized jet (R{sub B} ≈ 100-200). Low-level emission is detected throughout the near-background quiescent period between the first two emission episodes of the KW data, suggesting continued central-engine activity; we discuss the implications of this ongoing emission and its impact on the afterglow evolution and predictions. We summarize the varied sample of historical GRBs with exceptionally long durations in gamma-rays (≳1000 s) and discuss the likelihood of these events being from a separate population; we suggest ultra-long GRBs represent the tail of the duration distribution of the long GRB population.

  9. Observations of the intense and ultra-long burst GRB 041219a with the Germanium spectrometer on INTEGRAL

    NASA Astrophysics Data System (ADS)

    McBreen, S.; Hanlon, L.; McGlynn, S.; McBreen, B.; Foley, S.; Preece, R.; von Kienlin, A.; Williams, O. R.

    2006-08-01

    Context.GRB 041219a is the brightest burst localised by INTEGRAL. The peak flux of 43 ph cm-2 s-1 (1.84 × 10-5 erg cm-2 s-1, 20 keV-8 MeV, 1 s integration) is greater than that for ~98% of all bursts and the T_90 duration of ~186 s (~20 keV-8 MeV) is longer than all but a small number of bursts. The intense burst occurred about ~250 s after the precursor and the long delay enabled optical and near infrared telescopes to observe the prompt emission.Aims.We present comprehensive results of the temporal and spectral analyses, including line and afterglow searches using the spectrometer, SPI, aboard INTEGRAL, BAT on Swift and ASM on Rossi X-ray Timing Explorer. We avail of multi-wavelength data to generate broadband spectra of GRB 041219a and afterglow. Methods.Spectra for the burst and sub-intervals were fit by the Band model and also by the quasithermal model. The high resolution Germanium spectrometer data were searched for emission and absorption features and for γ-ray afterglow. Results. The overall burst and sub-intervals are well fit by the Band model. The photon index below the break energy shows a marked change after the quiescent time interval. In addition the spectra are well described by a black body component with a power law. The burst was detected by BAT and ASM during the long quiescent interval in SPI indicating the central engine might not be dormant but that the emission occurs in different bands. No significant emission or absorption features were found and limits of 900 eV and 120 eV are set on the most significant features. No γ-ray afterglow was detected from the end of the prompt phase to ~12 h post-burst. Broadband spectra of the prompt emission were generated in 7 time intervals using γ-ray, X-ray, optical and near-infrared data and these were compared to the high-redshift burst GRB 050904. The optical and γ-ray emission are correlated in GRB 041219a. We estimate isotropic radiated energy (E_iso) to be ~5 × 1052 erg. The spectral lag was

  10. The Decay of Optical Emission from the gamma-Ray Burst GRB970228

    NASA Technical Reports Server (NTRS)

    Galama, T.; Groot, P. J.; vanParadijs, J.; Kouveliotou, C.; Robinson, C. R.; Fishman, G. J.; Meegan, C. A.; Sahu, K. C.; Livio, M.; Petro, L.; Macchetto, F. D.; Heise, J.; Int Zand, J.; Strom, R. G.; Telting, J.; Rutten, R. G. M.; Pettini, M.; Tanvir, N.; Bloom, J.

    1997-01-01

    The origin of gamma-ray bursts has been one of the great unsolved mysteries in high-energy astrophysics for almost 30 years. The recent discovery of fading sources at X-ray and optical wavelengths coincident with the location of the gamma-ray burst GRB970228 therefore provides an unprecedented opportunity to probe the nature of these high-energy events. The optical counterpart appears to be a transient point source embedded in a region of extended nebulosity, the latter having been tentatively identified as a high-redshift galaxy. This would seem to favour models that place gamma-ray bursts at cosmological distances, although a range of mechanisms for producing the bursts is still allowed. A crucial piece of information for distinguishing between such models is how the brightness of the optical counterpart evolves with time. Here we re-evaluate the existing photometry of the optical counterpart of GRB970228 to construct an optical light curve for the transient event. We find that between 21 hours and six days after the burst, the R-band brightness decreased by a factor of approximately 40, with any subsequent decrease in brightness occurring at a much slower rate. As the point source faded, it also became redder. The initial behaviour of the source appears to be consistent with the 'fireball' model, but the subsequent decrease in the rate of fading may prove harder to explain.

  11. Preliminary analysis of GRB060607A within the fireshell model

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    GRB060607A is a very distant (z = 3.082) and energetic event (Eiso~1053 erg). Its main peculiarity is that the peak of the near-infrared afterglow has been observed with the REM robotic telescope, allowing to infer the initial Lorentz gamma factor of the emitting system. We present a preliminary analysis of the spectra and light curves of GRB060607A prompt emission within the fireshell model. We show that the N(E) spectrum of the prompt emission, whose behavior is usually described as ``simple power-law,'' can also be fitted in a satisfactory way by a convolution of thermal spectra as predicted by the model we applied. The theoretical time-integrated spectrum of the prompt emission as well as the light curves in the BAT and XRT energy band are in good agreement with the observations, enforcing the plausibility of our approach. Furthermore, the initial value of Lorentz gamma factor we predict is compatible with the one deduced from the REM observations.

  12. The central engine of GRB 130831A and the energy breakdown of a relativistic explosion

    NASA Astrophysics Data System (ADS)

    De Pasquale, M.; Oates, S. R.; Racusin, J. L.; Kann, D. A.; Zhang, B.; Pozanenko, A.; Volnova, A. A.; Trotter, A.; Frank, N.; Cucchiara, A.; Troja, E.; Sbarufatti, B.; Butler, N. R.; Schulze, S.; Cano, Z.; Page, M. J.; Castro-Tirado, A. J.; Gorosabel, J.; Lien, A.; Fox, O.; Littlejohns, O.; Bloom, J. S.; Prochaska, J. X.; de Diego, J. A.; Gonzalez, J.; Richer, M. G.; Román-Zúñiga, C.; Watson, A. M.; Gehrels, N.; Moseley, H.; Kutyrev, A.; Zane, S.; Hoette, V.; Russell, R. R.; Rumyantsev, V.; Klunko, E.; Burkhonov, O.; Breeveld, A. A.; Reichart, D. E.; Haislip, J. B.

    2016-01-01

    Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe, yet the nature and physical properties of their energy sources are far from understood. Very important clues, however, can be inferred by studying the afterglows of these events. We present optical and X-ray observations of GRB 130831A obtained by Swift, Chandra, Skynet, Reionization And Transients Infra-Red camera, Maidanak, International Scientific Optical-Observation Network, Nordic Optical Telescope, Liverpool Telescope and Gran Telescopio Canarias. This burst shows a steep drop in the X-ray light curve at ≃105 s after the trigger, with a power-law decay index of α ˜ 6. Such a rare behaviour cannot be explained by the standard forward shock (FS) model and indicates that the emission, up to the fast decay at 105 s, must be of `internal origin', produced by a dissipation process within an ultrarelativistic outflow. We propose that the source of such an outflow, which must produce the X-ray flux for ≃1 d in the cosmological rest frame, is a newly born magnetar or black hole. After the drop, the faint X-ray afterglow continues with a much shallower decay. The optical emission, on the other hand, shows no break across the X-ray steep decrease, and the late-time decays of both the X-ray and optical are consistent. Using both the X-ray and optical data, we show that the emission after ≃105 s can be explained well by the FS model. We model our data to derive the kinetic energy of the ejecta and thus measure the efficiency of the central engine of a GRB with emission of internal origin visible for a long time. Furthermore, we break down the energy budget of this GRB into the prompt emission, the late internal dissipation, the kinetic energy of the relativistic ejecta, and compare it with the energy of the associated supernova, SN 2013 fu.

  13. GRB Studies with Fermi

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    2008-01-01

    This slide presentation reviews the studies of Gamma Ray Bursts (GRB) with the Fermi Gamma Ray Space Telescope. Included are pictures of the observatory, with illustrations of the Large Area Telescope (LAT), and the Gamma-ray Burst Monitor (GBM) including information about both their capabilities. Graphs showing the GBM count rate over time after the GBM trigger for three GRBs, preliminary charts showing the multiple detector light curves the spectroscopy of the main LAT peak and the spectral evolution of GRB 080916C Burst Temporally-extended LAT emission.

  14. Host Extinction and Colour Evolution for GRB 030329

    NASA Astrophysics Data System (ADS)

    Holland, S. T.; Bersier, D.; Garnavich, P. M.; Stanek, K. Z.

    2003-12-01

    GRB 030329 was the Rosetta Stone that provided a convincing connection between cosmological gamma-ray bursts and core-collapse supernovae. In addition to demonstrating the supernova link GRB 030329 also exhibited other unusual features, such as a rebrightening after one day and a second jet break at approximately ten days. The optical afterglow also exhibited colour variations between between one and ten days after the burst. These variations may provide information about the physics of the afterglow, and the environment that the burst expanded into. We use the observed colours of the optical afterglow to constrain the extinction in the host galaxy along the line of sight to the burst, and to study the nature of the afterglow during its first few days. The authors would like to thank the staffs of the MMT, FLWO, Las Campanas, Lick, Keck, and Kitt Peak observatories for providing time to observe the optical afterglow of GRB 030329. The authors would also like to thank Scott Barthelmy and the GRB Coordinates Network for rapidly dissemination information of gamma-ray bursts and Arne Henden for providing photometric calibration of fields containing gamma-ray bursts. STH acknowledges support from NASA/LTSA grant NAG5-9364.

  15. Using Swift observations of prompt and afterglow emission to classify GRBs.

    PubMed

    O'Brien, Paul T; Willingale, Richard

    2007-05-15

    We present an analysis of early Burst Alert Telescope and X-ray Telescope data for 107 gamma-ray bursts (GRBs) observed by the Swift satellite. We use these data to examine the behaviour of the X-ray light curve and propose a classification scheme for GRBs based on this behaviour. As found for previous smaller samples, the earliest X-ray light curve can be well described by an exponential, which relaxes into a power-law, often with flares superimposed. The later emission is well fit using a similar functional form and we find that these two functions provide a good description of the entire X-ray light curve. For the prompt emission, the transition time between the exponential and the power-law gives a well-defined time-scale, Tp, for the burst duration. We use Tp, the spectral index of the prompt emission, betap, and the prompt power-law decay index, alphap, to define four classes of burst: short, slow, fast and soft. Bursts with slowly declining emission have spectral and temporal properties similar to the short bursts despite having longer durations. Some of these GRBs may therefore arise from similar progenitors including several types of binary system. Short bursts tend to decline more gradually than longer duration bursts and hence emit a significant fraction of their total energy at times greater than Tp. This may be due to differences in the environment or the progenitor for long, fast bursts. PMID:17293327

  16. Identifying the host galaxy of the short GRB 100628A

    NASA Astrophysics Data System (ADS)

    Nicuesa Guelbenzu, A.; Klose, S.; Palazzi, E.; Greiner, J.; Michałowski, M. J.; Kann, D. A.; Hunt, L. K.; Malesani, D.; Rossi, A.; Savaglio, S.; Schulze, S.; Xu, D.; Afonso, P. M. J.; Elliott, J.; Ferrero, P.; Filgas, R.; Hartmann, D. H.; Krühler, T.; Knust, F.; Masetti, N.; Olivares E., F.; Rau, A.; Schady, P.; Schmidl, S.; Tanga, M.; Updike, A. C.; Varela, K.

    2015-11-01

    We report on the results of a comprehensive observing campaign to reveal the host galaxy of the short GRB 100628A. This burst was followed by a faint X-ray afterglow but no optical counterpart was discovered. However, inside the X-ray error circle a potential host galaxy at a redshift of z = 0.102 was soon reported in the literature. If this system is the host, then GRB 100628A was the cosmologically most nearby unambiguous short burst with a measured redshift so far. We used the multi-colour imager GROND at the ESO/La Silla MPG 2.2 m telescope, ESO/VLT spectroscopy, and deep Australia Telescope Compact Array (ATCA) radio-continuum observations together with publicly available Gemini imaging data to study the putative host and the galaxies in the field of GRB 100628A. We confirm that inside the X-ray error circle the most probable host-galaxy candidate is the morphologically disturbed, interacting galaxy system at z = 0.102. The interacting galaxies are connected by a several kpc long tidal stream, which our VLT/FORS2 spectroscopy reveals strong emission lines of [O ii], [O iii], Hα and Hβ, characteristic for the class of extreme emission-line galaxies and indicative of ongoing star formation. The latter leaves open the possibility that the GRB progenitor was a member of a young stellar population. However, we indentify a second host-galaxy candidate slightly outside the X-ray error circle. It is a radio-bright, luminous elliptical galaxy at a redshift z = 0.311. With a K-band luminosity of 2 × 1011L⊙ this galaxy resembles the probable giant elliptical host of the first well-localized short burst, GRB 050509B. If this is the host, then the progenitor of GRB 100628A was a member of an old stellar population. Based on observations collected at the Very Large Telescope of the European Southern Observatory, Paranal, Chile (ESO programme 087.D-0503 and 290.D-5194; PI: A. Nicuesa Guelbenzu; 090.A-0825; PI: D. Malesani), GROND (PI: J. Greiner), and ATCA (Program C

  17. 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. PMID:17183318

  18. The Swift GRB Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Chincarini, Guido

    2004-01-01

    Swift is a MIDEX mission that is in development for launch in October 2004. It is a multiwavelength transient observatory for GRB astronomy. The goals of the mission are to determine the origin of GRBs and their afterglows and use bursts to probe the early Universe. A wide-field gamma-ray camera will detect mare than 100 GRBs per year to -3 times fainter than BATSE. Sensitive narrow-field X-ray and UV/optical telescopes will be pointed at the burst location in 20 to 75 sec by an autonomously controlled spacecraft. Far each burst, aresec positions will be determined and optical/UV/X-ray/gamma-say spectrophotometry performed. Measurements of redshift will be made for many burstes. The instrumentation is a combination of superb existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (approx. 0.5 square meter) CdZnTe detector array. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift. The talk vi11 describe the mission statue and give a summary of plans for GRB operations. It is likely that Swift will have just been launched at the time of the conference.

  19. GRB 050117: Simultaneous Gamma-ray and X-ray Observations with the Swift Satellite

    NASA Technical Reports Server (NTRS)

    Hill, J. E.; Morris, D. C.; Sakamoto, T.; Sato, G.; Burrows, D. N.; Angelini, L.; Pagani, C.; Moretti, A.; Abbey, A. F.; Barthelmy, S.

    2005-01-01

    The Swift Gamma-Ray Burst Explorer performed its first autonomous, X-ray follow-up to a newly detected GRB on 2005 January 17, within 193 seconds of the burst trigger by the Swift Burst Alert Telescope. While the burst was still in progress, the X-ray Telescope obtained a position and an image for an un-catalogued X-ray source; simultaneous with the gamma-ray observation. The XRT observed flux during the prompt emission was 1.1 x 10(exp -8) ergs/sq cm/s in the 0.5-10 keV energy band. The emission in the X-ray band decreased by three orders of magnitude within 700 seconds, following the prompt emission. This is found to be consistent with the gamma-ray decay when extrapolated into the XRT energy band. During the following 6.3 hours, the XRT observed the afterglow in an automated sequence for an additional 947 seconds, until the burst became fully obscured by the Earth limb. A faint, extremely slowly decaying afterglow, alpha=-0.21, was detected. Finally, a break in the lightcurve occurred and the flux decayed with alpha<-1.2. The X-ray position triggered many follow-up observations: no optical afterglow could be confirmed, although a candidate was identified 3 arcsecs from the XRT position.

  20. A search for pulsations from the compact object of GRB 060218

    NASA Astrophysics Data System (ADS)

    Mirabal, N.; Gotthelf, E. V.

    2010-02-01

    Aims: A fraction of massive stars are expected to collapse into compact objects (accreting black holes or rapidly rotating neutron stars) that successfully produce gamma-ray bursts (GRBs). We examine the possibility of directly observing these gamma-ray burst compact objects (GCOs) using post-explosion observations of past and future GRB sites. Methods: We present a search for early pulsations from the nearby (z=0.0335) gamma-ray burst GRB 060218, which exhibited features possibly consistent with a rapidly spinning neutron star as its underlying GCO. We also consider alternative techniques that could potentially achieve a detection of GCOs either in the Local Volume or near the plane of our own Galaxy. Results: We report the non-detection of pulsations from the GCO of GRB 060218. In particular, fast fourier transform analysis applied to the light curve shows no significant power over the range of frequencies 0.78 mHz < f < 227 Hz with an upper limit on the pulsed fraction of ~2%. In addition, we present detection limits of current high-resolution archival X-ray images of galaxies within the Local Volume. The existing data could be harnessed to rule out the presence of any background contaminants at the GRB position of future nearby events. Conclusions: The null detection of pulsations from the GCO of GRB 060218 is most likely explained by the fact that the afterglow emission occurs near the head of the jet and should be far removed from the compact object. We also find that the comparison of pre- and post-explosion explosion images of future GRBs within the Local Volume, as well as the firm identification of a GCO within an ancient GRB remnant near the Galactic plane are extremely challenging with current GeV/TeV capabilities. Finally, we conclude that only under some very exceptional circumstances will it be possible to directly detect the compact object responsible for gamma-ray bursts.

  1. The warm, the excited, and the molecular gas: GRB 121024A shining through its star-forming galaxy

    NASA Astrophysics Data System (ADS)

    Friis, M.; De Cia, A.; Krühler, T.; Fynbo, J. P. U.; Ledoux, C.; Vreeswijk, P. M.; Watson, D. J.; Malesani, D.; Gorosabel, J.; Starling, R. L. C.; Jakobsson, P.; Varela, K.; Wiersema, K.; Drachmann, A. P.; Trotter, A.; Thöne, C. C.; de Ugarte Postigo, A.; D'Elia, V.; Elliott, J.; Maturi, M.; Goldoni, P.; Greiner, J.; Haislip, J.; Kaper, L.; Knust, F.; LaCluyze, A.; Milvang-Jensen, B.; Reichart, D.; Schulze, S.; Sudilovsky, V.; Tanvir, N.; Vergani, S. D.

    2015-07-01

    We present the first reported case of the simultaneous metallicity determination of a gamma-ray burst (GRB) host galaxy, from both afterglow absorption lines as well as strong emission-line diagnostics. Using spectroscopic and imaging observations of the afterglow and host of the long-duration Swift GRB 121024A at z = 2.30, we give one of the most complete views of a GRB host/environment to date. We observe a strong damped Lyα absorber (DLA) with a hydrogen column density of log N({H I}) = 21.88± 0.10, H2 absorption in the Lyman-Werner bands (molecular fraction of log(f) ≈-1.4; fourth solid detection of molecular hydrogen in a GRB-DLA), the nebular emission lines Hα, Hβ, [O II], [O III] and [N II], as well as metal absorption lines. We find a GRB host galaxy that is highly star forming (SFR ˜ 40 M⊙ yr-1), with a dust-corrected metallicity along the line of sight of [Zn/H]corr = -0.6 ± 0.2 ([O/H] ˜ -0.3 from emission lines), and a depletion factor [Zn/Fe] = 0.85 ± 0.04. The molecular gas is separated by 400 km s-1 (and 1-3 kpc) from the gas that is photoexcited by the GRB. This implies a fairly massive host, in agreement with the derived stellar mass of log(M★/M⊙) = 9.9^{+0.2}_{-0.3}. We dissect the host galaxy by characterizing its molecular component, the excited gas, and the line-emitting star-forming regions. The extinction curve for the line of sight is found to be unusually flat (RV ˜ 15). We discuss the possibility of an anomalous grain size distributions. We furthermore discuss the different metallicity determinations from both absorption and emission lines, which gives consistent results for the line of sight to GRB 121024A.

  2. GRB 050717: A Long, Short-Lag Burst Observed by Swift and Konus

    NASA Technical Reports Server (NTRS)

    Krimm, H. A.; Hurkett, C.; Pal'shin, V.; Norris, J. P.; Zhang, B.; Barthelmy, S. D.; Burrows, D. N.; Gehrels, N.; Golenetskii, S.; Osborne, J. P.; Parsons, A. M.; Perri, M.; Willingale, R.

    2005-01-01

    The long burst GRB 050717 was observed simultaneously by the Burst Alert Telescope (BAT) on Swift and the Konus instrument on Wind. Significant hard to soft spectral evolution was seen. Early gamma-ray and X-ray emission was detected by both BAT and the X-Ray Telescope (XRT) on Swift. The XRT continued to observe the burst for 7.1 days and detect it for 1.4 days. The X-ray light curve showed a classic decay pattern including evidence of the onset of the external shock emission at approx. 50 s after the trigger; the afterglow was too faint for a jet break to be detected. No optical, infrared or ultraviolet counterpart was discovered despite deep searches within 14 hours of the burst. The spectral lag for GRB 050717 was determined to be 2.5 +/- 2.6 ms, consistent, with zero and unusually short for a long burst. This lag measurement suggests that this burst has a high intrinsic luminosity and hence is at high redshift (z > 2.7). 050717 provides a good example of classic prompt and afterglow behavior for a gamma-ray burst.

  3. 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.

  4. An external-shock model for gamma-ray burst afterglow 130427A

    NASA Astrophysics Data System (ADS)

    Panaitescu, A.; Vestrand, W. T.; Woźniak, P.

    2013-12-01

    The complex multiwavelength emission of gamma-ray burst (GRB) afterglow 130427A (monitored in the radio up to 10 d, in the optical and X-ray until 50 d, and at GeV energies until 1 d) can be accounted for by a hybrid reverse-forward shock synchrotron model, with inverse-Compton emerging only above a few GeV. The high ratio of the early optical to late radio flux requires that the ambient medium is a wind and that the forward-shock synchrotron spectrum peaks in the optical at about 10 ks. The latter has two consequences: the wind must be very tenuous and the optical emission before 10 ks must arise from the reverse-shock, as suggested also by the bright optical flash that Raptor has monitored during the prompt emission phase (<100 s). The Very Large Array radio emission is from the reverse-shock, the Swift X-ray emission is mostly from the forward-shock, but the both shocks give comparable contributions to the Fermi GeV emission. The weak wind implies a large blast-wave radius (8 t_day^{1/2} pc), which requires a very tenuous circumstellar medium, suggesting that the massive stellar progenitor of GRB 130427A resided in a superbubble.

  5. The Decay of Optical Emission Form the Gamma-Ray Burst GRB 970228

    NASA Technical Reports Server (NTRS)

    Galama, T.; Groot, P. J.; vanParadijs, J.; Kouvellotou, C.; Robinson, C. R.; Fishmans, G. J.; Meegan, C. A.; Sahu, K. C.; Livio, M.; Petro, L.

    1997-01-01

    The origin of gamma-ray bursts has been one of the great unsolved mysteries in high-energy astrophysics for almost 30 years. The recent discovery of fading sources at X-ray and optical wave-lengths coincident with the location of the gamma-ray burst GRB970228 therefore provides an unprecedented opportunity to probe the nature of these high-energy events. The optical counterpart appears to be a transient point source embedded in a region of extended nebulosity, the latter having been tentatively identified as a high-redshift galaxy. This would seem to favour models that place gamma-ray bursts at cosmological distances, although a range of mechanisms for producing the bursts is still allowed. A crucial piece of information for distinguishing between such models is how the brightness of the optical counterpart evolves with time. Here we re-evaluate the existing photometry of the optical counterpart of GRB970228 to construct an optical light curve for the transient event. We find that between 21 hours and six days after the burst, the R-band brightness decreased by a factor of approx. 50, with any subsequent decrease in brightness occurring at a much slower rate. As the point source faded, it also became redder. The initial behaviour of the source appears to be consistent with the 'fireball' model, in which the burst results from the merger of two neutron stars, but the subsequent decrease in the rate of fading may prove harder to explain. The gamma-ray burst of 28 February 1997, detected with the Gamma-Ray Burst Monitor on board the BeppoSAX satellite, and located with an approx. 3 feet radius position with the Wide Field Camera on the same satellite, was the first for which a fading X-ray and optical counterpart were discovered. The optical Counterpart was discovered from a comparison of V- and I-band images taken with the William Herschel Telescope (WHT) on February 28.99 UT, and the Isaac Newton Telescope (INT; V band) and the WHT (I band) on March 8.8 uT.

  6. CGRO/BATSE Data Support the New Paradigm for GRB Prompt Emission and the New LinTh-Epeak,inTh,rest Relation

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The paradigm for gamma-ray burst (GRB) prompt emission is changing. Since early in the Compton Gamma Ray Observatory (CGRO) era, the empirical Band function has been considered a good description of the keV-MeV γ-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 γ-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}{{i}}{nTh}, and its corresponding νF{}ν spectral peak energy, {E}{peak,{{i}}}{nTh} (i.e., {F}{{i}}{nTh}-{E}{peak,{{i}}}{nTh}), 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

  7. High energy emission of GRB 130821A: Constraining the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow

    SciTech Connect

    Liang, Yun-Feng; Zhou, Bei; He, Hao-Ning; Fan, Yi-Zhong; Wei, Da-Ming; Tam, Pak-Hin Thomas

    2014-02-01

    GRB 130821A was detected by Fermi-GBM/LAT, Konus-WIND, SPI-ACS/INTEGRAL, RHESSI and Mars Odyssey-HEND. Although the data of GRB 130821A are very limited, we show in this work that the high energy γ-ray emission (i.e., above 100 MeV) alone imposes tight constraint on the density profile of the circum-burst medium as well as the initial Lorentz factor of the outflow. The temporal behavior of the high energy γ-ray emission is consistent with the forward shock synchrotron radiation model, and the circum-burst medium likely has a constant-density profile. The Lorentz factor is about a few hundred, similar to other bright GRBs.

  8. Spectroscopy of the short-hard GRB 130603B. The host galaxy and environment of a compact object merger

    NASA Astrophysics Data System (ADS)

    de Ugarte Postigo, A.; Thöne, C. C.; Rowlinson, A.; García-Benito, R.; Levan, A. J.; Gorosabel, J.; Goldoni, P.; Schulze, S.; Zafar, T.; Wiersema, K.; Sánchez-Ramírez, R.; Melandri, A.; D'Avanzo, P.; Oates, S.; D'Elia, V.; De Pasquale, M.; Krühler, T.; van der Horst, A. J.; Xu, D.; Watson, D.; Piranomonte, S.; Vergani, S. D.; Milvang-Jensen, B.; Kaper, L.; Malesani, D.; Fynbo, J. P. U.; Cano, Z.; Covino, S.; Flores, H.; Greiss, S.; Hammer, F.; Hartoog, O. E.; Hellmich, S.; Heuser, C.; Hjorth, J.; Jakobsson, P.; Mottola, S.; Sparre, M.; Sollerman, J.; Tagliaferri, G.; Tanvir, N. R.; Vestergaard, M.; Wijers, R. A. M. J.

    2014-03-01

    Context. Short duration gamma-ray bursts (SGRBs) are thought to be related to the violent merger of compact objects, such as neutron stars or black holes, which makes them promising sources of gravitational waves. The detection of a "kilonova"-likesignature associated to the Swift-detected GRB 130603B has suggested that this event is the result of a compact object merger. Aims: Our knowledge on SGRB has been, until now, mostly based on the absence of supernova signatures and the analysis of the host galaxies to which they cannot always be securely associated. Further progress has been significantly hampered by the faintness and rapid fading of their optical counterparts (afterglows), which has so far precluded spectroscopy of such events. Afterglow spectroscopy is the key tool to firmly determine the distance at which the burst was produced, crucial to understand its physics, and study its local environment. Methods: Here we present the first spectra of a prototypical SGRB afterglow in which both absorption and emission features are clearly detected. Together with multi-wavelength photometry we study the host and environment of GRB 130603B. Results: From these spectra we determine the redshift of the burst to be z = 0.3565 ± 0.0002, measure rich dynamics both in absorption and emission, and a substantial line of sight extinction of AV = 0.86 ± 0.15 mag. The GRB was located at the edge of a disrupted arm of a moderately star forming galaxy with near-solar metallicity. Unlike for most long GRBs (LGRBs), NHX/AV is consistent with the Galactic ratio, indicating that the explosion site differs from those found in LGRBs. Conclusions: The merger is not associated with the most star-forming region of the galaxy; however, it did occur in a dense region, implying a rapid merger or a low natal kick velocity for the compact object binary. Appendices are available in electronic form at http://www.aanda.org

  9. Super-solar metallicity at the position of the ultra-long GRB 130925A

    NASA Astrophysics Data System (ADS)

    Schady, P.; Krühler, T.; Greiner, J.; Graham, J. F.; Kann, D. A.; Bolmer, J.; Delvaux, C.; Elliott, J.; Klose, S.; Knust, F.; Nicuesa Guelbenzu, A.; Rau, A.; Rossi, A.; Savaglio, S.; Schmidl, S.; Schweyer, T.; Sudilovsky, V.; Tanga, M.; Tanvir, N. R.; Varela, K.; Wiseman, P.

    2015-07-01

    Over the last decade there has been immense progress in the follow-up of short and long gamma-ray bursts (GRBs), resulting in a significant rise in the detection rate of X-ray and optical afterglows, in the determination of GRB redshifts, and of the identification of the underlying host galaxies. Nevertheless, our theoretical understanding of the progenitors and central engines powering these vast explosions is lagging behind, and a newly identified class of ultra-long GRBs has fuelled speculation on the existence of a new channel of GRB formation. In this paper we present high signal-to-noise X-Shooter observations of the host galaxy of GRB 130925A, which is the fourth unambiguously identified ultra-long GRB, with prompt γ-ray emission detected for ~20 ks. The GRB line of sight was close to the host galaxy nucleus, and our spectroscopic observations cover this region along the bulge/disk of the galaxy and a bright star-forming region within the outskirts of the galaxy. From our broad wavelength coverage, we obtain accurate metallicity and dust-extinction measurements at the galaxy nucleus and at an outer star-forming region, and measure a super-solar metallicity at both locations, placing this galaxy within the 10-20% most metal-rich GRB host galaxies. Such a high metal enrichment has significant implications on the progenitor models of both long and ultra-long GRBs, although the edge-on orientation of the host galaxy does not allow us to rule out a large metallicity variation along our line of sight. The spatially resolved spectroscopic observations presented in this paper offer important insight into variations in the metal and dust abundance within GRB host galaxies. However, they also illustrate the need for integral field unit observations on a larger sample of GRB host galaxies of a variety of metallicities to provide a more quantitative view on the relation between the GRB circumburst environment and the galaxy-whole properties. Based on observations taken

  10. GRB 110709A, 111117A, AND 120107A: FAINT HIGH-ENERGY GAMMA-RAY PHOTON EMISSION FROM FERMI-LAT OBSERVATIONS AND DEMOGRAPHIC IMPLICATIONS

    SciTech Connect

    Zheng Weikang; Akerlof, Carl W.; McKay, Timothy A.; Pandey, Shashi B.; Zhang Binbin; Zhang Bing; Sakamoto, Takanori

    2012-09-01

    Launched on 2008 June 11, the Large Area Telescope (LAT) instrument on board the Fermi Gamma-ray Space Telescope has provided a rare opportunity to study high-energy photon emission from gamma-ray bursts (GRBs). Although the majority of such events (27) have been identified by the Fermi-LAT Collaboration, four were uncovered by using more sensitive statistical techniques. In this paper, we continue our earlier work by finding three more GRBs associated with high-energy photon emission, GRB 110709A, 111117A, and 120107A. To systematize our matched filter approach, a pipeline has been developed to identify these objects in nearly real time. GRB 120107A is the first product of this analysis procedure. Despite the reduced threshold for identification, the number of GRB events has not increased significantly. This relative dearth of events with low photon number prompted a study of the apparent photon number distribution. We find an extremely good fit to a simple power law with an exponent of -1.8 {+-} 0.3 for the differential distribution. As might be expected, there is a substantial correlation between the number of lower energy photons detected by the Gamma-ray Burst Monitor (GBM) and the number observed by LAT. Thus, high-energy photon emission is associated with some but not all of the brighter GBM events. Deeper studies of the properties of the small population of high-energy emitting bursts may eventually yield a better understanding of these entire phenomena.

  11. GRB 110709A, 111117A, and 120107A: Faint High-energy Gamma-Ray Photon Emission from Fermi-LAT Observations and Demographic Implications

    NASA Astrophysics Data System (ADS)

    Zheng, WeiKang; Akerlof, Carl W.; Pandey, Shashi B.; McKay, Timothy A.; Zhang, BinBin; Zhang, Bing; Sakamoto, Takanori

    2012-09-01

    Launched on 2008 June 11, the Large Area Telescope (LAT) instrument on board the Fermi Gamma-ray Space Telescope has provided a rare opportunity to study high-energy photon emission from gamma-ray bursts (GRBs). Although the majority of such events (27) have been identified by the Fermi-LAT Collaboration, four were uncovered by using more sensitive statistical techniques. In this paper, we continue our earlier work by finding three more GRBs associated with high-energy photon emission, GRB 110709A, 111117A, and 120107A. To systematize our matched filter approach, a pipeline has been developed to identify these objects in nearly real time. GRB 120107A is the first product of this analysis procedure. Despite the reduced threshold for identification, the number of GRB events has not increased significantly. This relative dearth of events with low photon number prompted a study of the apparent photon number distribution. We find an extremely good fit to a simple power law with an exponent of -1.8 ± 0.3 for the differential distribution. As might be expected, there is a substantial correlation between the number of lower energy photons detected by the Gamma-ray Burst Monitor (GBM) and the number observed by LAT. Thus, high-energy photon emission is associated with some but not all of the brighter GBM events. Deeper studies of the properties of the small population of high-energy emitting bursts may eventually yield a better understanding of these entire phenomena.

  12. The plateau phase of gamma-ray burst afterglows in the thick-shell scenario

    NASA Astrophysics Data System (ADS)

    Leventis, K.; Wijers, R. A. M. J.; van der Horst, A. J.

    2014-01-01

    We present analytic calculations of synchrotron radiation from the forward and the reverse shock of gamma-ray burst blast waves, in the thick-shell scenario (i.e. when the reverse shock is relativistic). We show that this scenario can naturally account for the plateau phase, observed early in the afterglows of about half the bursts detected by Swift. We generalize our approach to include power-law luminosity of the central engine and show that when radiation from both regions (forward and reverse shock) is taken into account, a wide range of possibilities emerge, including chromatic and achromatic breaks, frequency-dependent spectral evolution during the injection break and widely varying decay indices in different bands. For both the forward and the reverse shock, we derive formulas for the spectral parameters and the observed flux in different power-law segments of the spectrum, as a function of observer time. We explore the Fb-tb relation (between the observed time of the end of the plateau phase and the flux at that point) in the framework of the presented model and show that model predictions favour the reverse shock as the dominant source of emission in both optical and X-rays. As case studies, we present simultaneous fits to X-ray and optical/IR afterglow data of GRB 080928 and GRB 090423. We identify the end of the plateau phase with the cessation of energy injection and infer the corresponding upper limits to central-engine activity, which are about 1 h for the former and 1.5 h for the latter. We conclude that smooth energy injection through the reverse shock is a plausible explanation for the plateau phase of gamma-ray burst afterglows. During that phase, radiation from the reverse shock is likely to be important, or even dominant, and should be taken into account when fitting model parameters to observations.

  13. 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.

  14. Jet or Shock Breakout? The Low-Luminosity GRB 060218

    NASA Astrophysics Data System (ADS)

    Irwin, Christopher M.; Chevalier, Roger A.

    2016-05-01

    We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived (tj ˜ 3000 s) central engine and accompanying low-luminosity (Lj ˜ 1047 erg s-1), mildly relativistic (γ ˜ 10) jet; (2) a low-mass (˜4 × 10-3M⊙) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ˜ 0.1 mag) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the nonthermal X-rays and γ-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ˜1013 cm can explain the early optical emission. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ˜30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that bursts such as GRB 060218 may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt emission from the supernova.

  15. Jet or shock breakout? The low-luminosity GRB 060218

    NASA Astrophysics Data System (ADS)

    Irwin, Christopher M.; Chevalier, Roger A.

    2016-08-01

    We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived (tj ˜ 3000 s) central engine and accompanying low-luminosity (Lj ˜ 1047 erg s-1), mildly relativistic (γ ˜ 10) jet; (2) a low-mass (˜4 × 10-3 M⊙) envelope surrounding the progenitor star; and (3) a modest amount of dust (AV ˜ 0.1 mag) in the circumstellar or interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the non-thermal X-rays and gamma-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to ˜1013 cm can explain the early optical emission. The X-ray afterglow can be interpreted as a light echo of the prompt emission from dust at ˜30 pc. Our model is a plausible alternative to that of Nakar, who recently proposed shock breakout of a jet smothered by an extended envelope as the source of prompt emission. Both our results and Nakar's suggest that bursts such as GRB 060218 may originate from unusual progenitors with extended circumstellar envelopes, and that a jet is necessary to decouple the prompt emission from the supernova.

  16. EARLY AFTERGLOWS OF GAMMA-RAY BURSTS IN A STRATIFIED MEDIUM WITH A POWER-LAW DENSITY DISTRIBUTION

    SciTech Connect

    Yi, Shuang-Xi; Dai, Zi-Gao; Wu, Xue-Feng

    2013-10-20

    A long-duration gamma-ray burst (GRB) has been widely thought to arise from the collapse of a massive star, and it has been suggested that its ambient medium is a homogenous interstellar medium (ISM) or a stellar wind. There are two shocks when an ultra-relativistic fireball that has been ejected during the prompt gamma-ray emission phase sweeps up the circumburst medium: a reverse shock that propagates into the fireball, and a forward shock that propagates into the ambient medium. In this paper, we investigate the temporal evolution of the dynamics and emission of these two shocks in an environment with a general density distribution of n∝R {sup –k} (where R is the radius) by considering thick-shell and thin-shell cases. A GRB afterglow with one smooth onset peak at early times is understood to result from such external shocks. Thus, we can determine the medium density distribution by fitting the onset peak appearing in the light curve of an early optical afterglow. We apply our model to 19 GRBs and find that their k values are in the range of 0.4-1.4, with a typical value of k ∼ 1, implying that this environment is neither a homogenous ISM with k = 0 nor a typical stellar wind with k = 2. This shows that the progenitors of these GRBs might have undergone a new mass-loss evolution.

  17. Strategy and results of East Asian GRB FOllow-up Network (EAFON) follow-up observations

    NASA Astrophysics Data System (ADS)

    Urata, Y.; Eafon Team

    We have established Japan-Taiwan-China collaboration on GRBs study in the East-Asian region since 2004 This serves as valuable additions to the world-wide optical and infrared follow-up network because the East-Asia region is otherwise blank for the network We have been carrying out imaging and spectroscopic follow-up observations by Lulin Taiwan Kiso Japan WIDGET Japan and Xinglong China Using Xinglong and Kiso we can locate candidates and obtain early time spectra of afterglows While WIDGET provides early time observations before the burst the high-time resolution for multi-band light curves will be obtained by Lulin With the data from these sites we will obtain detailed information of light curve and redshift of GRBs which are important to understand the mechanism of afterglows Utilizing East Asian GRB Follow-up Observation Network EAFON we have observed 56 GRB optical afterglows and detected 15 early optical afterglow behavior including two short GRBs in multi-bands Based on these observations we have obtained 3 major results 1 first long term monitoring of short GRB afterglow from sim 0 1 days after the burst 2 two components in early optical afterglow 3 catch about 30 high redshift GRB candidates In this meeting we will present mainly report early a common feature of long GRB early afterglow We have found a common feature in long GRB early afterglow light curves These early light curves show re-brightening and or plateau phase around 0 1 days 2 4hours after bursts Combined with other prompt

  18. DISCOVERY OF SN 2009nz ASSOCIATED WITH GRB 091127

    SciTech Connect

    Cobb, B. E.; Bloom, J. S.; Perley, D. A.; Morgan, A. N.; Cenko, S. B.; Filippenko, A. V.

    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 straightforward 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.

  19. Swift observations of GRB 050904: the most distant cosmic explosion ever observed

    NASA Astrophysics Data System (ADS)

    Cusumano, G.; Mangano, V.; Chincarini, G.; Panaitescu, A.; Burrows, D. N.; La Parola, V.; Sakamoto, T.; Campana, S.; Mineo, T.; Tagliaferri, G.; Angelini, L.; Barthelmy, S. D.; Beardmore, A. P.; Boyd, P. T.; Cominsky, L. R.; Gronwall, C.; Fenimore, E. E.; Gehrels, N.; Giommi, P.; Goad, M.; Hurley, K.; Immler, S.; Kennea, J. A.; Mason, K. O.; Marshal, F.; Mészáros, P.; Nousek, J. A.; Osborne, J. P.; Palmer, D. M.; Roming, P. W. A.; Wells, A.; White, N. E.; Zhang, B.

    2007-01-01

    Context: Swift discovered the high redshift (z=6.29) GRB 050904 with the Burst Alert Telescope (BAT) and began observing with its narrow field instruments 161 s after the burst onset. This gamma-ray burst is the most distant cosmic explosion ever observed. Because of its high redshift, the X-ray Telescope (XRT) and BAT simultaneous observations provide 4 orders of magnitude of spectral coverage (0.2-150 keV; 1.4-1090 keV in the source rest frame) at a very early source-frame time (22 s). The X-ray emission was monitored by the XRT up to 10 days after the burst. Aims: We present the analysis of BAT and XRT observations of GRB 050904 and a complete description of its high energy phenomenology. Methods: We performed time resolved spectral analysis and light curve modeling. Results: GRB 050904 was a long, multi-peaked, bright GRB with strong variability during its entire evolution. The light curve observed by the XRT is characterized by the presence of a long flaring activity lasting up to 1-2 h after the burst onset in the burst rest frame, with no evidence of a smooth power-law decay following the prompt emission as seen in other GRBs. However, the BAT tail extrapolated to the XRT band joins the XRT early light curve and the overall behavior resembles that of a very long GRB prompt. The spectral energy distribution softens with time, with the photon index decreasing from -1.2 during the BAT observation to -1.9 at the end of the XRT observation. The dips of the late X-ray flares may be consistent with an underlying X-ray emission arising from the forward shock and with the properties of the optical afterglow reported by Tagliaferri et al. (2005b, A&A, 443, L1). Conclusions: . We interpret the BAT and XRT data as a single continuous observation of the prompt emission from a very long GRB. The peculiarities observed in GRB 050904 could be due to its origin within one of the first star-forming regions in the Universe; very low metallicities of the progenitor at these

  20. GRB 080319B: A Naked-Eye Stellar Blast from the Distant Universe

    SciTech Connect

    Racusin, J. L.; Burrows, D. N.

    2008-10-22

    On behalf of a large international collaboration [1], we present the unprecedented broadband observations of GRB 080319B, whose prompt optical emission peaked at a visual magnitude of 5.3, making it briefly visible with the naked eye. GRB 080319B was discovered by Swift and captured in exquisite detail by ground based wide-field telescopes, imaging the burst location from before the time of the explosion. The combination of these unique optical data with simultaneous {gamma}-ray observations provides powerful diagnostics of the detailed physics of this explosion within seconds of its formation. We show that the prompt optical and {gamma}-ray emissions from this event arise from different spectral components within the same physical region located at a large distance from the source, implying an extremely relativistic outflow. Our observations also provide good evidence for a bright reverse shock component. The chromatic behavior of the broadband afterglow is consistent with viewing the GRB down the very narrow inner core of a two-component jet that is expanding into a wind-like environment consistent with the massive star origin of long GRBs.

  1. Prompt GRB optical follow-up experiments

    SciTech Connect

    Park, H-S; Williams, G; Ables, E; Band, D; Barthelmy, S; Bionta, R; Cline, T; Gehrels, N; Hartmann, D; Hurley, K; Kippen, M; Nemiroff, R; Pereira, W; Porrata, R

    2000-11-13

    Gamma Ray Bursts (GRBs) are brief, randomly located, releases of gamma-ray energy from unknown celestial sources that occur almost daily. The study of GRBs has undergone a revolution in the past three years due to an international effort of follow-up observations of coordinates provided by Beppo/SAX and IPN GRB. These follow-up observations have shown that GRBs are at cosmological distances and interact with surrounding material as described by the fireball model. However, prompt optical counterparts have only been seen in one case and are therefore very rare or much dimmer than the sensitivity of the current instruments. Unlike later time afterglows, prompt optical measurements would provide information on the GRB progenitor. LOTIS is the very first automated and dedicated telescope system that actively utilizes the GRB Coordinates Network (GCN) and it attempts to measure simultaneous optical light curve associated with GRBs. After 3 years of running, LOTIS has responded to 75 GRB triggers. The lack of any optical signal in any of the LOTIS images places numerical limits on the surrounding matter density, and other physical parameters in the environment of the GRB progenitor. This paper presents LOTIS results and describes other prompt GRB follow-up experiments including the Super-LOTIS at Kitt Peak in Arizona.

  2. Broadband observations of the naked-eye gamma-ray burst GRB 080319B.

    PubMed

    Racusin, J L; Karpov, S V; Sokolowski, M; Granot, J; Wu, X F; Pal'shin, V; Covino, S; van der Horst, A J; Oates, S R; Schady, P; Smith, R J; Cummings, J; Starling, R L C; Piotrowski, L W; Zhang, B; Evans, P A; Holland, S T; Malek, K; Page, M T; Vetere, L; Margutti, R; Guidorzi, C; Kamble, A P; Curran, P A; Beardmore, A; Kouveliotou, C; Mankiewicz, L; Melandri, A; O'Brien, P T; Page, K L; Piran, T; Tanvir, N R; Wrochna, G; Aptekar, R L; Barthelmy, S; Bartolini, C; Beskin, G M; Bondar, S; Bremer, M; Campana, S; Castro-Tirado, A; Cucchiara, A; Cwiok, M; D'Avanzo, P; D'Elia, V; Valle, M Della; de Ugarte Postigo, A; Dominik, W; Falcone, A; Fiore, F; Fox, D B; Frederiks, D D; Fruchter, A S; Fugazza, D; Garrett, M A; Gehrels, N; Golenetskii, S; Gomboc, A; Gorosabel, J; Greco, G; Guarnieri, A; Immler, S; Jelinek, M; Kasprowicz, G; La Parola, V; Levan, A J; Mangano, V; Mazets, E P; Molinari, E; Moretti, A; Nawrocki, K; Oleynik, P P; Osborne, J P; Pagani, C; Pandey, S B; Paragi, Z; Perri, M; Piccioni, A; Ramirez-Ruiz, E; Roming, P W A; Steele, I A; Strom, R G; Testa, V; Tosti, G; Ulanov, M V; Wiersema, K; Wijers, R A M J; Winters, J M; Zarnecki, A F; Zerbi, F; Mészáros, P; Chincarini, G; Burrows, D N

    2008-09-11

    Long-duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the optical flash in detail and the accuracy needed to trace the transition from the prompt emission within the outflow to external shocks caused by interaction with the progenitor environment. Here we report observations of the extraordinarily bright prompt optical and gamma-ray emission of GRB 080319B that provide diagnostics within seconds of its formation, followed by broadband observations of the afterglow decay that continued for weeks. We show that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet. PMID:18784718

  3. ON PARTICLE ACCELERATION RATE IN GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Sagi, Eran; Nakar, Ehud

    2012-04-10

    It is well known that collisionless shocks are major sites of particle acceleration in the universe, but the details of the acceleration process are still not well understood. The particle acceleration rate, which can shed light on the acceleration process, is rarely measured in astrophysical environments. Here, we use observations of gamma-ray burst (GRB) afterglows, which are weakly magnetized relativistic collisionless shocks in ion-electron plasma, to constrain the rate of particle acceleration in such shocks. We find, based on X-ray and GeV afterglows, an acceleration rate that is most likely very fast, approaching the Bohm limit, when the shock Lorentz factor is in the range of {Gamma} {approx} 10-100. In that case X-ray observations may be consistent with no amplification of the magnetic field in the shock upstream region. We examine the X-ray afterglow of GRB 060729, which is observed for 642 days showing a sharp decay in the flux starting about 400 days after the burst, when the shock Lorentz factor is {approx}5. We find that inability to accelerate X-ray-emitting electrons at late time provides a natural explanation for the sharp decay, and that also in that case acceleration must be rather fast, and cannot be more than a 100 times slower than the Bohm limit. We conclude that particle acceleration is most likely fast in GRB afterglows, at least as long as the blast wave is ultrarelativistic.

  4. A REVERSE SHOCK IN GRB 130427A

    SciTech Connect

    Laskar, T.; Berger, E.; Zauderer, B. A.; Margutti, R.; Soderberg, A. M.; Chakraborti, S.; Lunnan, R.; Chornock, R.; Chandra, P.; Ray, A.

    2013-10-20

    We present extensive radio and millimeter observations of the unusually bright GRB 130427A at z = 0.340, spanning 0.67-12 days after the burst. We combine these data with detailed multi-band UV, optical, NIR, and Swift X-ray observations and find that the broadband afterglow emission is composed of distinct reverse shock and forward shock contributions. The reverse shock emission dominates in the radio/millimeter and at ∼< 0.1 days in the UV/optical/NIR, while the forward shock emission dominates in the X-rays and at ∼> 0.1 days in the UV/optical/NIR. We further find that the optical and X-ray data require a wind circumburst environment, pointing to a massive star progenitor. Using the combined forward and reverse shock emission, we find that the parameters of the burst include an isotropic kinetic energy of E{sub K,{sub iso}} ≈ 2 × 10{sup 53} erg, a mass loss rate of M-dot ∼3×10{sup -8} M{sub ☉} yr{sup –1} (for a wind velocity of 1000 km s{sup –1}), and a Lorentz factor at the deceleration time of Γ(200 s) ≈ 130. Due to the low density and large isotropic energy, the absence of a jet break to ≈15 days places only a weak constraint on the opening angle, θ{sub j} ∼> 2.°5, and therefore a total energy of E{sub γ} + E{sub K} ∼> 1.2 × 10{sup 51} erg, similar to other gamma-ray bursts (GRBs). The reverse shock emission is detectable in this burst due to the low circumburst density, which leads to a slow cooling shock. We speculate that this property is required for the detectability of reverse shocks in radio and millimeter bands. Following on GRB 130427A as a benchmark event, observations of future GRBs with the exquisite sensitivity of the Very Large Array and ALMA, coupled with detailed modeling of the reverse and forward shock contributions, will test this hypothesis.

  5. A Statistical Study of GRB X-Ray Flares: Evidence of Ubiquitous Bulk Acceleration in the Emission Region

    NASA Astrophysics Data System (ADS)

    Jia, Lan-Wei; Uhm, Z. Lucas; Zhang, Bing

    2016-07-01

    When emission in a conical relativistic jet ceases abruptly (or decays sharply), the observed decay light curve is controlled by the high-latitude “curvature effect.” Recently, Uhm & Zhang found that the decay slopes of three gamma-ray burst (GRB) X-ray flares are steeper than what the standard model predicts. This requires bulk acceleration of the emission region, which is consistent with a Poynting-flux-dominated outflow. In this paper, we systematically analyze a sample of 85 bright X-ray flares detected in 63 Swift GRBs and investigate the relationship between the temporal decay index α and spectral index β during the steep decay phase of these flares. The α values depend on the choice of the zero time point t 0. We adopt two methods. “Method I” takes {t}0{{I}} as the first rising data point of each flare and is the most conservative approach. We find that at the 99.9% confidence level 56/85 flares have decay slopes steeper than the simplest curvature effect prediction and therefore are in the acceleration regime. “Method II” extrapolates the rising light curve of each flare backward until the flux density is three orders of magnitude lower than the peak flux density, and it defines the corresponding time as the zero time point ({t}0{{II}}). We find that 74/85 flares fall into the acceleration regime at the 99.9% confidence level. This suggests that bulk acceleration is common and may even be ubiquitous among X-ray flares, pointing toward a Poynting-flux-dominated jet composition for these events.

  6. GLAST Prospects for Swift-Era Afterglows

    SciTech Connect

    Gou, L.J.; Meszaros, P.; /Penn State U.

    2011-11-23

    We calculate the GeV spectra of gamma-ray burst afterglows produced by inverse Compton scattering of these objects sub-MeV emission. We improve on earlier treatments by using refined afterglow parameters and new model developments motivated by recent Swift observations. We present time-dependent GeV spectra for standard, constant-parameter models, as well as for models with energy injection and with time-varying parameters, for a range of burst parameters. We evaluate the limiting redshift to which such afterglows can be detected by the GLAST Large Area Telescope, as well as by AGILE.

  7. X-Ray Afterglow Light Curves: Toward A Standard Candle?

    NASA Astrophysics Data System (ADS)

    Gendre, B.; Galli, A.; Boër, M.

    2008-08-01

    We investigate the clustering of afterglow light curves observed at X-ray and optical wavelengths. We have constructed a sample of 61 bursts with known distance and X-ray afterglow. This sample includes bursts observed by BeppoSAX, XMM-Newton, Chandra, and Swift. We correct the light curves for cosmological effects and compare the observed X-ray fluxes 1 day after the burst. We check for correlations between the observed flux and the burst spectral and temporal properties. We confirm the previous result of Boër & Gendre that X-ray afterglow light curves cluster in luminosity, even when we consider the last Swift data. We observe this clustering only for the afterglow light curves; the inclusion of prompt-related data broadens the distribution. A similar clustering is observed for the optical light curves; gamma-ray burst (GRB) sources can be divided into three classes, namely, optically and X-ray bright afterglows, optically and X-ray dim ones, and optically bright but X-ray dim ones. We argue that this clustering is related to the fireball total energy, the external medium density, and the fraction of fireball energy going into relativistic electrons and magnetic fields. These parameters can be either fixed to a standard value or correlated. We finally propose a method for the estimation of the GRB source redshift based on the observed X-ray flux 1 day after the burst and optical properties. Using this method, we compute a redshift of 1.4 +/- 0.2 for GRB 980519 and of 1.9 +/- 0.3 for GRB 040827. We tested this method on three recently detected Swift GRBs with known redshift, and found it in good agreement with the reported distance from optical spectroscopy.

  8. Gamma-ray burst radio afterglows from Population III stars: simulation methods and detection prospects with SKA precursors

    NASA Astrophysics Data System (ADS)

    Macpherson, D.; Coward, D.

    2015-10-01

    We investigate the prospects of detecting radio afterglows from long Gamma-Ray Bursts (GRBs) from Population III (Pop III) progenitors using the Square Kilometre Array (SKA) precursor instruments MWA (Murchison Widefield Array) and ASKAP (Australian SKA Pathfinder). We derive a realistic model of GRB afterglows that encompasses the widest range of plausible physical parameters and observation angles. We define the best case scenario of Pop III GRB energy and redshift distributions. Using probability distribution functions fitted to the observed microphysical parameters of long GRBs, we simulate a large number of Pop III GRB afterglows to find the global probability of detection. We find that ASKAP may be able to detect 35 per cent of Pop III GRB afterglows in the optimistic case, and 27 per cent in the pessimistic case. A negligible number will be detectable by MWA in either case. Detections per image for ASKAP, found by incorporating intrinsic rates with detectable time-scales, are as high as ˜6000 and as low as ˜11, which shows the optimistic case is unrealistic. We track how the afterglow flux density changes over various time intervals and find that, because of their very slow variability, the cadence for blind searches of these afterglows should be as long as possible. We also find Pop III GRBs at high redshift have radio afterglow light curves that are indistinguishable from those of regular long GRBs in the more local Universe.

  9. 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.; Ashley, M. C. B.; Barthelmy, S. D.; Bersier, D.; CastroCeron, J. M.; Castro-Tirado, A. J.; Gehrels, N.; Gogus, E.; Gorosabel, J.; Guidorzi, C.; Guver, T.; Hjorth, J.; Horns, D.; Huang, K. Y.; Jakobsson, P.; Jensen, B. L.

    2007-01-01

    We report on follow-up observations of the gamma-ray burst GRB 060927 using the robotic ROTSE-IIIa telescope and a suite of larger aperture groundbased telescopes. An optical afterglow was detected 20 s after the burst, the earliest rest-frame detection of optical emission from any GRB. Spectroscopy performed with the VLT about 13 hours after the trigger shows a continuum break at lambda approx. equals 8070 A, produced by neutral hydrogen absorption at zeta = 5.6. We also detect an absorption line at 8158 A which we interpret as Si II lambda 1260 at zeta = 5.467. Hence, GRB 060927 is the second most distant GRB with a spectroscopically measured redshift. The shape of the red wing of the spectral break can be fitted by a damped Ly(alpha) profile with a column density with log(N(sub HI)/sq cm) = 22.50 +/- 0.15. We discuss the implications of this work for the use of GRBs as probes of the end of the dark ages and draw three main conclusions: i) GRB afterglows originating from zeta greater than or approx. equal to 6 should be relatively easy to detect from the ground, but rapid near-infrared monitoring is necessary to ensure that they are found; ii) The presence of large H I column densities in some GRBs host galaxies at zeta > 5 makes the use of GRBs to probe the reionization epoch via spectroscopy of the red damping wing challenging; iii) GRBs appear crucial to locate typical star-forming galaxies at zeta > 5 and therefore the type of galaxies responsible for the reionization of the universe.

  10. Induced gravitational collapse in the BATSE era: The case of GRB 970828

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Following the recently established "Binary-driven HyperNova" (BdHN) model, we here interpret GRB 970828 in terms of the four episodes typical of such a model. The "Episode 1," up to 40 s after the trigger time t 0, with a time varying thermal emission and a total energy of Eiso,1st = 2.60 × 1053 erg, is interpreted as due to the onset of an hyper-critical accretion process onto a companion neutron star, triggered by the companion star, an FeCO core undergoing a SN explosion. The "Episode 2," observed up t 0 + 90 s, is interpreted as a canonical gamma ray burst, with an energy of erg, a baryon load of B = 7× 10-3 and a bulk Lorentz factor at transparency of G = 142.5. From this Episode 2, we infer that the GRB exploded in an environment with a large average particle density ≈103 particles/cm3 and dense clouds characterized by typical dimensions of (4-8) × 1014 cm and δn/n ~ 10. The "Episode 3" is identified from t 0 +90 s all the way up to 105-6 s: despite the paucity of the early X-ray data, typical in the BATSE, pre-Swift era, we find extremely significant data points in the late X-ray afterglow emission of GRB 970828, which corresponds to the ones observed in all BdHNe sources. The "Episode 4," related to the Supernova emission, does not appear to be observable in this source, due to the presence of darkening from the large density of the GRB environment, also inferred from the analysis of the Episode 2.

  11. An External Shock Origin of GRB 141028A

    NASA Astrophysics Data System (ADS)

    Burgess, J. Michael; Bégué, Damien; Ryde, Felix; Omodei, Nicola; Pe’er, Asaf; Racusin, J. L.; Cucchiara, A.

    2016-05-01

    The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB 141028A, is analyzed under the guise of an external shock model. First, we fit the γ-ray spectrum with a two-component photon model, namely, synchrotron+blackbody, and then fit the recovered evolution of the synchrotron νF ν peak to an analytic model derived considering the emission of a relativistic blast wave expanding into an external medium. The prediction of the model for the νF ν peak evolution matches well with the observations. We observe the blast wave transitioning into the deceleration phase. Furthermore, we assume the expansion of the blast wave to be nearly adiabatic, motivated by the low magnetic field deduced from the observations. This allows us to recover within an order of magnitude the flux density at the νF ν peak, which is remarkable considering the simplicity of the analytic model. Under this scenario we argue that the distinction between prompt and afterglow emission is superfluous as both early-time emission and late-time emission emanate from the same source. While the external shock model is clearly not a universal solution, this analysis opens the possibility that at least some fraction of GRBs can be explained with an external shock origin of their prompt phase.

  12. Gamma-ray Bursts and their Afterglows in the Whole Electromagnetic Domain

    NASA Astrophysics Data System (ADS)

    Castro-Tirado, Alberto J.

    2007-08-01

    Since their discovery in 1967, GRBs have been puzzling to astrophysicists. With the advent of a new generation of X--ray satellites in the late 90's, it was possible to carry out deep multi-wavelength observations of the counterparts associated with the long GRBs class just within a few hours of occurrence, thanks to the observation of the fading X-ray emission that follows the more energetic gamma-ray photons once the GRB event has ended. The fact that this emission (the afterglow) extends at longer wavelengths, led to the discovery optical/IR/radio counterparts in the last decade, greatly improving our understanding of these sources. The launch of the Swift satellite in 2004 allows to detect about 100 events/yr, with a mean redshift of 2.7 for the long duration GRB class. The central engines that power these extraordinary events are thought to be the collapse of massive stars whereas the merging of compact objects seems to support the few detections of short GRBs detected so far. Searches for emission at VHE and UHE have been unsuccessful till now.

  13. 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.

  14. The signature of the central engine in the weakest relativistic explosions: GRB 100316D

    SciTech Connect

    Margutti, R.; Soderberg, A. M.; Sironi, L.; Zauderer, B. A.; Milisavljevic, D.; Kamble, A.; Wieringa, M. H.; Edwards, P. G.; Chevalier, R. A.; Morsony, B. J.; Duran, R. Barniol; Pian, E.

    2013-11-20

    We present late-time radio and X-ray observations of the nearby sub-energetic gamma-ray burst (GRB)100316D associated with supernova (SN) 2010bh. Our broad-band analysis constrains the explosion properties of GRB 100316D to be intermediate between highly relativistic, collimated GRBs and the spherical, ordinary hydrogen-stripped SNe. We find that ∼10{sup 49} erg is coupled to mildly relativistic (Γ = 1.5-2), quasi-spherical ejecta, expanding into a medium previously shaped by the progenitor mass-loss with a rate of M-dot ∼ 10{sup −5} M{sub ⊙} yr{sup −1} (for an assumed wind density profile and wind velocity v{sub w} = 1000 km s{sup –1}). The kinetic energy profile of the ejecta argues for the presence of a central engine and identifies GRB 100316D as one of the weakest central-engine-driven explosions detected to date. Emission from the central engine is responsible for an excess of soft X-ray radiation that dominates over the standard afterglow at late times (t > 10 days). We connect this phenomenology with the birth of the most rapidly rotating magnetars. Alternatively, accretion onto a newly formed black hole might explain the excess of radiation. However, significant departure from the standard fall-back scenario is required.

  15. The Signature of the Central Engine in the Weakest Relativistic Explosions: GRB 100316D

    NASA Astrophysics Data System (ADS)

    Margutti, R.; Soderberg, A. M.; Wieringa, M. H.; Edwards, P. G.; Chevalier, R. A.; Morsony, B. J.; Barniol Duran, R.; Sironi, L.; Zauderer, B. A.; Milisavljevic, D.; Kamble, A.; Pian, E.

    2013-11-01

    We present late-time radio and X-ray observations of the nearby sub-energetic gamma-ray burst (GRB)100316D associated with supernova (SN) 2010bh. Our broad-band analysis constrains the explosion properties of GRB 100316D to be intermediate between highly relativistic, collimated GRBs and the spherical, ordinary hydrogen-stripped SNe. We find that ~1049 erg is coupled to mildly relativistic (Γ = 1.5-2), quasi-spherical ejecta, expanding into a medium previously shaped by the progenitor mass-loss with a rate of \\dot{M}\\, {\\sim }\\, 10^{-5}\\,M_{\\odot }\\,yr^{-1} (for an assumed wind density profile and wind velocity vw = 1000 km s-1). The kinetic energy profile of the ejecta argues for the presence of a central engine and identifies GRB 100316D as one of the weakest central-engine-driven explosions detected to date. Emission from the central engine is responsible for an excess of soft X-ray radiation that dominates over the standard afterglow at late times (t > 10 days). We connect this phenomenology with the birth of the most rapidly rotating magnetars. Alternatively, accretion onto a newly formed black hole might explain the excess of radiation. However, significant departure from the standard fall-back scenario is required.

  16. Messages from GRB 060218.

    PubMed

    Zhang, Bing; Liang, Enwei; Gupta, Nayantara; Zhang, Bin-Bin; Virgili, Francisco; Dai, Z G

    2007-05-15

    GRB 060218 is a watershed event. Statistically, its detection suggests that there is likely a distinct low-luminosity (LL) population of gamma-ray bursts (GRBs) whose event rate is much higher than that of conventional high-luminosity GRBs. This LL population may give significant contribution to the diffuse neutrino background flux at energies higher than 1016eV. The spectral lag of this burst is very long, and roughly follows the luminosity-lag relation of normal GRBs. This, along with the fact that it follows the Ep-Eiso relation as well, suggests that X-ray flashes (XRFs) are natural extension of GRBs in the softer regime and that GRBs and XRFs share the same radiation physics. We discuss how the broadband data pose strong constraints on possible models of the prompt emission of this GRB. PMID:17293314

  17. Modeling the Afterglow of the Possible Fermi-GBM event Associated with GW150914

    NASA Astrophysics Data System (ADS)

    Morsony, Brian J.; Workman, Jared C.; Ryan, Dominic M.

    2016-07-01

    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 after 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.

  18. GRB 090510: A Disguised Short Gamma-Ray Burst with the Highest Lorentz Factor and Circumburst Medium

    NASA Astrophysics Data System (ADS)

    Muccino, M.; Ruffini, R.; Bianco, C. L.; Izzo, L.; Penacchioni, A. V.; Pisani, G. B.

    2013-07-01

    GRB 090510, observed by both Fermi and AGILE satellites, is the first bright short-hard gamma-ray burst (GRB) with an emission from the keV up to the GeV energy range. Within the Fireshell model, we interpret the faint precursor in the light curve as the emission at the transparency of the expanding e + e - plasma: the Proper-GRB. From the observed isotropic energy, we assume a total plasma energy E^{tot}_{e^+e^-}=(1.10+/- 0.06)\\times 10^{53} erg and derive a Baryon load B = (1.45 ± 0.28) × 10-3 and a Lorentz factor at transparency Γtr = (6.7 ± 1.6) × 102. The main emission ~0.4 s after the initial spike is interpreted as the extended afterglow, due to the interaction of the ultrarelativistic baryons with the CircumBurst Medium (CBM). Using the condition of fully radiative regime, we infer a CBM average spherically symmetric density of langn CBMrang = (1.85 ± 0.14) × 103 particles cm-3, one of the highest found in the Fireshell model. The value of the filling factor, 1.5\\times 10^{-10}\\le {R}\\le 3.8\\times 10^{-8}, leads to the estimate of filaments with densities n_{fil}=n_{CBM}/ {R}\\approx (10^{6}{--}10^{14}) particles cm-3. The sub-MeV and the MeV emissions are well reproduced. When compared to the canonical GRBs with langn CBMrang ≈ 1 particles cm-3 and to the disguised short GRBs with langn CBMrang ≈ 10-3 particles cm-3, the case of GRB 090510 leads to the existence of a new family of bursts exploding in an overdense galactic region with langn CBMrang ≈ 103 particles cm-3. The joint effect of the high Γtr and the high density compresses in time and "inflates" in intensity the extended afterglow, making it appear as a short burst, which we here define as a "disguised short GRB by excess." The determination of the above parameter values may represent an important step toward the explanation of the GeV emission.

  19. GRB 090510: A DISGUISED SHORT GAMMA-RAY BURST WITH THE HIGHEST LORENTZ FACTOR AND CIRCUMBURST MEDIUM

    SciTech Connect

    Muccino, M.; Ruffini, R.; Bianco, C. L.; Izzo, L.; Penacchioni, A. V.; Pisani, G. B.

    2013-07-20

    GRB 090510, observed by both Fermi and AGILE satellites, is the first bright short-hard gamma-ray burst (GRB) with an emission from the keV up to the GeV energy range. Within the Fireshell model, we interpret the faint precursor in the light curve as the emission at the transparency of the expanding e {sup +} e {sup -} plasma: the Proper-GRB. From the observed isotropic energy, we assume a total plasma energy E{sup tot}{sub e{sup +}e{sup -}}=(1.10{+-}0.06) Multiplication-Sign 10{sup 53} erg and derive a Baryon load B = (1.45 {+-} 0.28) Multiplication-Sign 10{sup -3} and a Lorentz factor at transparency {Gamma}{sub tr} = (6.7 {+-} 1.6) Multiplication-Sign 10{sup 2}. The main emission {approx}0.4 s after the initial spike is interpreted as the extended afterglow, due to the interaction of the ultrarelativistic baryons with the CircumBurst Medium (CBM). Using the condition of fully radiative regime, we infer a CBM average spherically symmetric density of (n{sub CBM}) = (1.85 {+-} 0.14) Multiplication-Sign 10{sup 3} particles cm{sup -3}, one of the highest found in the Fireshell model. The value of the filling factor, 1.5 Multiplication-Sign 10{sup -10}{<=}R{<=}3.8 Multiplication-Sign 10{sup -8}, leads to the estimate of filaments with densities n{sub fil} = n{sub CBM}/R approx. (10{sup 6}-10{sup 14}) particles cm{sup -3}. The sub-MeV and the MeV emissions are well reproduced. When compared to the canonical GRBs with (n{sub CBM}) Almost-Equal-To 1 particles cm{sup -3} and to the disguised short GRBs with (n{sub CBM}) Almost-Equal-To 10{sup -3} particles cm{sup -3}, the case of GRB 090510 leads to the existence of a new family of bursts exploding in an overdense galactic region with (n{sub CBM}) Almost-Equal-To 10{sup 3} particles cm{sup -3}. The joint effect of the high {Gamma}{sub tr} and the high density compresses in time and 'inflates' in intensity the extended afterglow, making it appear as a short burst, which we here define as a 'disguised short GRB by excess

  20. Prompt and Afterglow Emmision Properties of Gamma-ray Bursts with Spectroscopically Identified Supernovae

    NASA Technical Reports Server (NTRS)

    Kaneko, Yuki; Ramirez-Ruiz, Enrico; Granot, Jonathan; Kouveliotou, Chryssa; Woosley, Stan E.; Patel, Sandeep K.; Rol, Evert; In'TZant, Jean J. M.; VanDerHorst, Alexander J.; Wijers, Ralph A. M. J.; Strom, Richard

    2007-01-01

    We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425,030329,031203, and 060218) that were spectroscopically found to be associated with Type IC supernovae and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolution and estimate the total energy budget based on broadband observations. The observational inventory for these events has become rich enough to allow estimates of their energy content in relativistic and subrelativistic form. The result is a global portrait of the effects of the physical processes responsible for producing long-soft GRBs. In particular, we find that the values of the energy released in mildly relativistic out8ows appears to have a sigruficantly smaller scatter than those found in highly relativistic ejecta. This is consistent with a picture in which the energy released inside the progenitor star is roughly standard, while the fracti

  1. A late-time flattening of light curves in gamma-ray burst afterglows

    SciTech Connect

    Sironi, Lorenzo; Giannios, Dimitrios E-mail: dgiannio@purdue.edu

    2013-12-01

    The afterglow emission from gamma-ray bursts (GRBs) is usually interpreted as synchrotron radiation from relativistic electrons accelerated at the GRB external shock. We investigate the temporal decay of the afterglow emission at late times, when the bulk of the shock-accelerated electrons are non-relativistic (the 'deep Newtonian phase', as denoted by Huang and Cheng). We assume that the electron spectrum in the deep Newtonian phase is a power-law distribution in momentum with slope p, as dictated by the theory of Fermi acceleration in non-relativistic shocks. For a uniform circumburst medium, the deep Newtonian phase begins at t{sub DN}∼3 ϵ{sub e,−1}{sup 5/6}t{sub ST}, where t {sub ST} marks the transition of the blast wave to the non-relativistic, spherically symmetric Sedov-Taylor (ST) solution, and ε {sub e} = 0.1 ε {sub e,–1} quantifies the amount of shock energy transferred to the electrons. For typical parameters, the deep Newtonian stage starts ∼0.5 to several years after the GRB. The radio flux in this phase decays as F {sub ν}∝t {sup –3(p+1)/10}∝t {sup –(0.9÷1.2)}, for a power-law slope 2 < p < 3. This is shallower than the scaling F {sub ν}∝t {sup –3(5p–7)/10}∝t {sup –(0.9÷2.4)} derived by Frail et al., which only applies if the GRB shock is non-relativistic, but the electron distribution still peaks at ultra-relativistic energies (a regime that is relevant for a narrow time interval, and only if t {sub DN} ≳ t {sub ST}, namely, ε {sub e} ≳ 0.03). We discuss how the deep Newtonian phase can be reliably used for GRB calorimetry, and we comment on the good detection prospects of trans-relativistic blast waves at 0.1÷10 GHz with the Karl G. Jansky Very Large Array and LOw-Frequency ARray.

  2. 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.; 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.; Krivonos, R. A.; Grebenev, S. A.; Sunyaev, R. A.

    2007-01-01

    GRB 070610 is a typical high-energy event with a duration of 5s.Yet within the burst localization we detect a highly unusual X-ray and optical transient, SwiftJ195509.6+261406. We see high amplitude X-ray and optical variability on very short time scares even at late times. Using near-infrared imaging assisted by a laser guide star and adaptive optics, we identified the counterpart of SwiftJl95509.6+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 sub-class 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

  3. DISCOVERY OF A TIGHT CORRELATION FOR GAMMA-RAY BURST AFTERGLOWS WITH 'CANONICAL' LIGHT CURVES

    SciTech Connect

    Dainotti, Maria Giovanna; Ostrowski, Michal; Willingale, Richard; Capozziello, Salvatore; Cardone, Vincenzo Fabrizio E-mail: mio@oa.uj.edu.p E-mail: capozziello@na.infn.i

    2010-10-20

    Gamma-ray bursts (GRBs) observed up to redshifts z>8 are fascinating objects to study due to their still unexplained relativistic outburst mechanisms and their possible use to test cosmological models. Our analysis of 77 GRB afterglows with known redshifts revealed a physical subsample of long GRBs with the canonical plateau breaking to power-law light curves with a significant luminosity L*{sub X}-break time T*{sub a} correlation in the GRB rest frame. This subsample forms approximately the upper envelope of the studied distribution. We have also found a similar relation for a small sample of GRB afterglows that belong to the intermediate class between the short and the long ones. It proves that within the full sample of afterglows there exist physical subclasses revealed here by tight correlations of their afterglow properties. The afterglows with regular ('canonical') light curves obey not only the mentioned tight physical scaling, but-for a given T*{sub a}-the more regular progenitor explosions lead to preferentially brighter afterglows.

  4. An External Shock Origin of GRB 141028A

    NASA Astrophysics Data System (ADS)

    Burgess, Michael; Bégué, Damien

    2016-07-01

    The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB 141028A, is analyzed under the guise of an external shock model. First, we fit the γ-ray spectrum with a two-component photon model, namely synchrotron+blackbody, and then fit the recovered evolution of the synchrotron ν F_{ν} peak to an analytic model derived considering the emission of a relativistic blast-wave expanding into an external medium. The prediction of the model for the ν F_{ν} peak evolution matches well with the observations. We observe the blast-wave transitioning into the deceleration phase. Further we assume the expansion of the magnetic field deduced from the observations. This allows us to recover within an order of magnitude the flux density at the ν F_{ν} peak, which is remarkable considering the simplicity of the analytic model. Under this scenario we argue that the distinction between prompt and afterglow emission is superfluous as both early and late time emission emanate from the same source. While the external shock model is clearly not a universal solution, this analysis opens the possibility that at least some fraction of GRBs can be explained with an external shock origin of their prompt phase.

  5. Fermi/GBM observations of the ultra-long GRB 091024. A burst with an optical flash

    NASA Astrophysics Data System (ADS)

    Gruber, D.; Krühler, T.; Foley, S.; Nardini, M.; Burlon, D.; Rau, A.; Bissaldi, E.; von Kienlin, A.; McBreen, S.; Greiner, J.; Bhat, P. N.; Briggs, M. S.; Burgess, J. M.; Chaplin, V. L.; Connaughton, V.; Diehl, R.; Fishman, G. J.; Gibby, M. H.; Giles, M. M.; Goldstein, A.; Guiriec, S.; van der Horst, A. J.; Kippen, R. M.; Kouveliotou, C.; Lin, L.; Meegan, C. A.; Paciesas, W. S.; Preece, R. D.; Tierney, D.; Wilson-Hodge, C.

    2011-04-01

    Aims: In this paper we examine gamma-ray and optical data of GRB 091024, a gamma-ray burst (GRB) with an extremely long duration of T90 ≈ 1020 s, as observed with the Fermi Gamma-ray Burst Monitor (GBM). Methods: We present spectral analysis of all three distinct emission episodes using data from Fermi/GBM. Because of the long nature of this event, many ground-based optical telescopes slewed to its location within a few minutes and thus were able to observe the GRB during its active period. We compare the optical and gamma-ray light curves. Furthermore, we estimate a lower limit on the bulk Lorentz factor from the variability and spectrum of the GBM light curve and compare it with that obtained from the peak time of the forward shock of the optical afterglow. Results: From the spectral analysis we note that, despite its unusually long duration, this burst is similar to other long GRBs, i.e. there is spectral evolution (both the peak energy and the spectral index vary with time) and spectral lags are measured. We find that the optical light curve is highly anti-correlated to the prompt gamma-ray emission, with the optical emission reaching the maximum during an epoch of quiescence in the prompt emission. We interpret this behavior as the reverse shock (optical flash), expected in the internal-external shock model of GRB emission but observed only in a handful of GRBs so far. The lower limit on the initial Lorentz factor deduced from the variability time scale (Γmin = 195_{-110+90}) is consistent within the error to the one obtained using the peak time of the forward shock (Γ0 = 120) and is also consistent with Lorentz factors of other long GRBs.

  6. Imprints of Electron–Positron Winds on the Multiwavelength Afterglows of Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Geng, J. J.; Wu, X. F.; Huang, Y. F.; Li, L.; Dai, Z. G.

    2016-07-01

    Optical rebrightenings in the afterglows of some gamma-ray bursts (GRBs) are unexpected within the framework of the simple external shock model. While it has been suggested that the central engines of some GRBs are newly born magnetars, we aim to relate the behaviors of magnetars to the optical rebrightenings. A newly born magnetar will lose its rotational energy in the form of Poynting-flux, which may be converted into a wind of electron–positron pairs through some magnetic dissipation processes. As proposed by Dai, this wind will catch up with the GRB outflow and a long-lasting reverse shock (RS) would form. By applying this scenario to GRB afterglows, we find that the RS propagating back into the electron–positron wind can lead to an observable optical rebrightening and a simultaneous X-ray plateau (or X-ray shallow decay). In our study, we select four GRBs (i.e., GRB 080413B, GRB 090426, GRB 091029, and GRB 100814A), of which the optical afterglows are well observed and show clear rebrightenings. We find that they can be well interpreted. In our scenario, the spin-down timescale of the magnetar should be slightly smaller than the peak time of the rebrightening, which can provide a clue to the characteristics of the magnetar.

  7. Afterglow Complex Plasma

    SciTech Connect

    Samarian, A. A.; Boufendi, L.; Mikikian, M.

    2008-09-07

    The review of the first detailed experimental and theoretical studies of complex plasma in RF discharge afterglow is presented. The studies have been done in a frame of FAST collaborative research project between Complex Plasma Laboratory of the University of Sydney and the GREMI laboratory of Universite d'Orleans. We examined the existing models of plasma decay, presents experimental observations of dust dynamics under different afterglow complex plasma conditions, presents the experimental data obtained (in particular the presence of positively charged particles in discharge afterglow), discusses the use of dust particles as a probe to study the diffusion losses in afterglow plasmas.

  8. An optical spectrum of the afterglow of a gamma-ray burst at a redshift of z = 6.295.

    PubMed

    Kawai, N; Kosugi, G; Aoki, K; Yamada, T; Totani, T; Ohta, K; Iye, M; Hattori, T; Aoki, W; Furusawa, H; Hurley, K; Kawabata, K S; Kobayashi, N; Komiyama, Y; Mizumoto, Y; Nomoto, K; Noumaru, J; Ogasawara, R; Sato, R; Sekiguchi, K; Shirasaki, Y; Suzuki, M; Takata, T; Tamagawa, T; Terada, H; Watanabe, J; Yatsu, Y; Yoshida, A

    2006-03-01

    The prompt gamma-ray emission from gamma-ray bursts (GRBs) should be detectable out to distances of z > 10 (ref. 1), and should therefore provide an excellent probe of the evolution of cosmic star formation, reionization of the intergalactic medium, and the metal enrichment history of the Universe. Hitherto, the highest measured redshift for a GRB has been z = 4.50 (ref. 5). Here we report the optical spectrum of the afterglow of GRB 050904 obtained 3.4 days after the burst; the spectrum shows a clear continuum at the long-wavelength end of the spectrum with a sharp cut-off at around 9,000 A due to Lyman alpha absorption at z approximately 6.3 (with a damping wing). A system of absorption lines of heavy elements at z = 6.295 +/- 0.002 was also detected, yielding the precise measurement of the redshift. The Si ii fine-structure lines suggest a dense, metal-enriched environment around the progenitor of the GRB. PMID:16525466

  9. Fast-response optical and near-infrared GRB science with RATIR and RIMAS

    NASA Astrophysics Data System (ADS)

    Capone, John; RIMAS Collaboration, RATIR project Team

    2016-01-01

    As the Universe's most luminous transient events, long gamma-ray bursts (GRBs) are observed at cosmological distances. The afterglow emission generated by the burst's interaction with the surrounding medium presents the opportunity to study the local environment, as well as intervening systems. The transient nature of these events requires observations starting within minutes of the GRB to maximize the scientific opportunities.This dissertation work comprises efforts to advance the field with a new instrument, the Rapid Infrared Imager and Spectrograph (RIMAS). The optical design is complicated by the broad band coverage (0.97 to 2.39 microns) and the necessity of transmissive optics due to space and weight limitations on the telescope. Additionally, the entire optical system must be cooled to cryogenic temperatures to decrease the background from thermal emission. The completed instrument will be permanently installed on Lowell Observatory's new 4.3 meter Discovery Channel Telescope (DCT) located in Happy Jack, Arizona. The fast slew time of the telescope, combined with the instrument's ability to image in two bands simultaneously and switch to spectroscopic configurations in under a minute will allow observers to obtain photometric data within minutes and spectra within ~ ten minutes.In addition to instrumentation work on RIMAS's optics, early time photometric light curves have been studied primarily using data from the Reionization and Transients Infrared/Optical Project (RATIR). Early time photometric data in six optical and near-infrared (NIR) bands has allowed a study of color evolution in the early to late time SEDs. This study probes possible impacts of the GRB on the local medium as well as intrinsic changes in the afterglow emission.This work is made possible by the RATIR and RIMAS collaborations as well as financial support by the NSF.

  10. Multiwavelength observations of the energetic GRB 080810: detailed mapping of the broad-band spectral evolution

    NASA Astrophysics Data System (ADS)

    Page, K. L.; Willingale, R.; Bissaldi, E.; Postigo, A. De Ugarte; Holland, S. T.; McBreen, S.; O'Brien, P. T.; Osborne, J. P.; Prochaska, J. X.; Rol, E.; Rykoff, E. S.; Starling, R. L. C.; Tanvir, N. R.; van der Horst, A. J.; Wiersema, K.; Zhang, B.; Aceituno, F. J.; Akerlof, C.; Beardmore, A. P.; Briggs, M. S.; Burrows, D. N.; Castro-Tirado, A. J.; Connaughton, V.; Evans, P. A.; Fynbo, J. P. U.; Gehrels, N.; Guidorzi, C.; Howard, A. W.; Kennea, J. A.; Kouveliotou, C.; Pagani, C.; Preece, R.; Perley, D.; Steele, I. A.; Yuan, F.

    2009-11-01

    GRB 080810 was one of the first bursts to trigger both Swift and the Fermi Gamma-ray Space Telescope. It was subsequently monitored over the X-ray and UV/optical bands by Swift, in the optical by Robotic Optical Transient Search Experiment (ROTSE) and a host of other telescopes, and was detected in the radio by the Very Large Array. The redshift of z = 3.355 +/- 0.005 was determined by Keck/High Resolution Echelle Spectrometer (HIRES) and confirmed by RTT150 and NOT. The prompt gamma/X-ray emission, detected over 0.3-103 keV, systematically softens over time, with Epeak moving from ~600 keV at the start to ~40 keV around 100s after the trigger; alternatively, this spectral evolution could be identified with the blackbody temperature of a quasi-thermal model shifting from ~60 to ~3keV over the same time interval. The first optical detection was made at 38s, but the smooth, featureless profile of the full optical coverage implies that this is originated from the afterglow component, not from the pulsed/flaring prompt emission. Broad-band optical and X-ray coverage of the afterglow at the start of the final X-ray decay (~8ks) reveals a spectral break between the optical and X-ray bands in the range of 1015-2 × 1016Hz. The decay profiles of the X-ray and optical bands show that this break initially migrates blueward to this frequency and then subsequently drifts redward to below the optical band by ~3 × 105s. GRB 080810 was very energetic, with an isotropic energy output for the prompt component of 3 × 1053 and 1.6 × 1052 erg for the afterglow; there is no evidence for a jet break in the afterglow up to 6d following the burst. This paper is dedicated to the memory of Professor Martin Turner, who sadly passed away during its writing. Martin was an influential figure in X-ray Astronomy and an excellent PhD supervisor. He will be greatly missed. E-mail: kpa@star.le.ac.uk ‡ NASA postdoctoral program fellow.

  11. The host of GRB 060206: kinematics of a distant galaxy

    NASA Astrophysics Data System (ADS)

    Thöne, C. C.; Wiersema, K.; Ledoux, C.; Starling, R. L. C.; de Ugarte Postigo, A.; Levan, A. J.; Fynbo, J. P. U.; Curran, P. A.; Gorosabel, J.; van der Horst, A. J.; Llorente, A.; Rol, E.; Tanvir, N. R.; Vreeswijk, P. M.; Wijers, R. A. M. J.; Kewley, L. J.

    2008-10-01

    Context: GRB afterglow spectra are sensitive probes of interstellar matter along the line-of-sight in their host galaxies, as well as in intervening galaxies. The rapid fading of GRBs makes it very difficult to obtain spectra of sufficient resolution and S/N to allow for these kinds of studies. Aims: We investigate the state and properties of the interstellar medium in the host of GRB 060206 at z= 4.048 with a detailed study of groundstate and finestructure absorption lines in an early afterglow spectrum. This allows us to derive conclusions on the nature and origin of the absorbing structures and their connection to the host galaxy and/or the GRB. Methods: We used early (starting 1.6 h after the burst) WHT/ISIS optical spectroscopy of the afterglow of the gamma-ray burst GRB 060206 detecting a range of metal absorption lines and their finestructure transitions. Additional information is provided by the afterglow lightcurve. The resolution and wavelength range of the spectra and the bright afterglow have facilitated a detailed study and fitting of the absorption line systems in order to derive column densities. We also used deep imaging to detect the host galaxy and probe the nature of an intervening system at z = 1.48 seen in absorption in the afterglow spectra. Results: We detect four discrete velocity systems in the resonant metal absorption lines, best explained by shells within and/or around the host created by starburst winds. The finestructure lines have no less than three components with strengths decreasing from the redmost components. We therefore suggest that the finestructure lines are best explained as being produced by UV pumping from which follows that the redmost component is the one closest to the burst where N V was detected as well. The host is detected in deep HST imaging with F814WAB = 27.48 ± 0.19 mag and a 3σ upper limit of H = 20.6 mag (Vega) is achieved. A candidate counterpart for the intervening absorption system is detected as well

  12. 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.; Schady, P.; Afonso, P. M. J.; Clemens, C.; Filgas, R.; KuepcuYoldas, A.; McBreen, S.; Olivares, F.; Szokoly, G.; Yoldas, A.; Krimm, H. A.; Johannesson, G.; Panaitescu, A.; Yuan, F.; Pandey, S. B.; Akerlof, C. W.

    2010-01-01

    We present the results of a comprehensive study of the Gamma-Ray Burst 080928 and of its afterglow. GRB 08092 was a long burst detected by Swift/BAT and Fermi/GBM, It is one of the exceptional cases where optical emission was already detected when the GRB itself was still radiating in the gamma-ray band. for nearly 100 seconds simultaneous optical X-ray and gamma-ray data provide a coverage of the spectral energy distribution of the transient source from about 1 eV to 150 keV. Here we analyze the prompt emission, constrain its spectral propertIes. and set lower limits on the initial Lorentz factor of the relativistic outflow, In particular. we show that the SED during the main prompt emission phase is in agreement with synchrotron radiation. We construct the optical/near-infrared light curve and the spectral energy distribution based on Swift/UVOT. ROTSE-Illa (Australia) and GROND (La Silla) data and compare it to the X-ray light curve retrieved from the Swift/XRT repository. We show that its bumpy shape can be modeled by multiple energy injections into the forward shock. Furthermore, we provide evidence that the temporal and spectral evolution of the first strong flare seen in the early X-ray light curve can be explained by large-angle emission. Finally, we report on the results of our search for the GRB host galaxy, for which only a deep upper limit can be provided.

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

    SciTech Connect

    Karlica, Mile

    2015-12-17

    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.

  14. The hidden X-ray breaks in afterglow light curves

    SciTech Connect

    Curran, P. A.; Wijers, R. A. M. J.; Horst, A. J. van der; Starling, R. L. C.

    2008-05-22

    Gamma-Ray Burst (GRB) afterglow observations in the Swift era have a perceived lack of achromatic jet breaks compared to the BeppoSAX, or pre-Swift era. Specifically, relatively few breaks, consistent with jet breaks, are observed in the X-ray light curves of these bursts. If these breaks are truly missing, it has serious consequences for the interpretation of GRB jet collimation and energy requirements, and the use of GRBs as standard candles.Here we address the issue of X-ray breaks which are possibly 'hidden' and hence the light curves are misinterpreted as being single power-laws. We show how a number of precedents, including GRB 990510 and GRB 060206, exist for such hidden breaks and how, even with the well sampled light curves of the Swift era, these breaks may be left misidentified. We do so by synthesising X-ray light curves and finding general trends via Monte Carlo analysis. Furthermore, in light of these simulations, we discuss how to best identify achromatic breaks in afterglow light curves via multi-wavelength analysis.

  15. Swift and GRB's: Unveiling the Relativistic Universe

    NASA Technical Reports Server (NTRS)

    Marshall, Francis E.

    2006-01-01

    We report Swift observations of GRB 051109A, a bright, long burst detected with BAT. A bright afterglow was quickly detected with the X-Ray Telescope and Ultraviolet and Optical Telescope, and observations continued for more than 10 days. The X-ray light is complex with a rapid initial decay followed by a more gradual decay. There is evidence for a jet break with an indicated opening angle of a few degrees. UVOT observations with the V filter are consistent with a power-law day for the first 10 ks. We discuss the observations in light of current models.

  16. The Interplanetary GRB Network in 2002

    NASA Astrophysics Data System (ADS)

    Cline, T. L.; Barthelmy, S. D.; Hurley, K. C.; Anfimov, D.; Mitrofanov, I.; Golenetskii, S.; Mazets, E.; Crew, G.; Ricker, G.; Frontera, F.; Montanari, E.; Guidorzi, C.; Feroci, M.

    2002-04-01

    The Interplanetary GRB Network (IPN) has been recently enhanced with the successful addition of the Mars Odyssey mission. This compensates for the loss in 2001 of the asteroid mission NEAR, reconstituting a fully long-baseline interplanetary triangle with Ulysses, also in deep space, and with GGS-Wind, BeppoSAX and HETE-2, near the Earth. The operation of the renewed IPN has been demonstrated with the detection of many SGR and solar events in recent months, and with an appropriate detection rate of GRBs. The observations to date and the afterglow detections that the IPN has enabled will be outlined, and the future performance will be discussed.

  17. THE ANTICIPATED SUPERNOVA ASSOCIATED WITH GRB 090618

    SciTech Connect

    Dado, Shlomo; Dar, Arnon E-mail: arnon@physics.technion.ac.il

    2010-01-10

    We use the cannonball model of gamma-ray bursts (GRBs) and public data from the first day of observations of GRB 090618 to predict its X-ray and optical light curves until very late times, and, in particular, the emergence of a photometric and spectroscopic signature of an SN akin to SN1998bw in its optical afterglow with an anticipated peak brightness of magnitude {approx}23.2 in the R band around 2009 July 10, if extinction in the host galaxy can be neglected.

  18. Gamma-ray burst afterglows as probes of their host galaxies and the cosmos

    NASA Astrophysics Data System (ADS)

    Cucchiara, Antonino

    2010-12-01

    Gamma-ray Bursts (GRBs) represent the sole class of catastrophic phenomena seen over almost the entire history of the Universe. Their extreme luminosities in high energy gamma-ray radiation make them readily detectable, even with relatively small satellite-based detectors, out to the earliest cosmic epochs. Moreover, the brilliance of their fading afterglow light, routinely observed in X-ray, optical, near-infrared, and radio wavelengths, allows them to be exploited -- for hours, days, or weeks -- as cosmic lighthouses, probing the conditions of gas and dust along the line of sight, through their host galaxies and the cosmos at large. Since the November 2004 launch of Swift, this GRB-focused NASA mission has discovered more than 500 GRBs, in almost all cases reporting the burst coordinates to ground-based observers within seconds of the event. The availability of prompt burst positions from Swift, combined with promptly-reported flux measurements from instruments on Swift and an array of ground-based robotic telescopes, have enabled targeted spectroscopic campaigns that have gathered detailed observations of the young, bright afterglows of hundreds of these events. This thesis reports the results of my own efforts over the past 5 years, analyzing imaging and spectroscopic observations of Swift-detected GRBs as triggered according to my own requests, or as gathered from public data archives. In Chapter 2, I discuss our follow-up campaign for GRB090429B, one of our best "extreme redshift" (z > 8) candidates. This burst followed closely on the spectroscopicallyconfirmed z = 8.2 GRB090423, and our multiwavelength observations and SED modeling demonstrate the value and limitation of such studies, in cases where a spectroscopic redshift cannot be gathered in a timely fashion. I also address the importance of such extreme-redshift events from a cosmological perspective. In Chapter 3, I use high-resolution GRB afterglow spectra to study the properties of intervening

  19. X-ray afterglow light curves: toward a standard candle?

    NASA Astrophysics Data System (ADS)

    Gendre, B.; Galli, A.; Boër, M.

    2008-05-01

    We investigate the clustering of afterglow light curves observed at X-ray and optical wavelengths. We construct a sample of 34 bursts with known distance and X-ray afterglow. We correct the light curves for cosmological effects and compare the observed X-ray fluxes one day after the burst. We check for correlations between the observed flux and the burst spectral and temporal properties. We confirm the previous result of Boër and Gendre (2000) that X-ray afterglow light curves cluster in luminosity, even when we consider the SWIFT data. We observe this clustering only for the afterglow light curves; the inclusion of prompt-related data broaden the distribution. The same clustering is observed for the optical light curves; GRB sources can be divided in three classes, namely optical and X-ray bright afterglows, optical and X-ray dim ones, and optically bright-X-ray dim ones. We argue that this clustering is related to the fireball total energy, the external medium density, the fraction of fireball energy going in relativistic electrons and magnetic fields. These parameters can be either fixed to a standard value, or correlated.

  20. A trio of gamma-ray burst supernovae:. GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu

    NASA Astrophysics Data System (ADS)

    Cano, Z.; de Ugarte Postigo, A.; Pozanenko, A.; Butler, N.; Thöne, C. C.; Guidorzi, C.; Krühler, T.; Gorosabel, J.; Jakobsson, P.; Leloudas, G.; Malesani, D.; Hjorth, J.; Melandri, A.; Mundell, C.; Wiersema, K.; D'Avanzo, P.; Schulze, S.; Gomboc, A.; Johansson, A.; Zheng, W.; Kann, D. A.; Knust, F.; Varela, K.; Akerlof, C. W.; Bloom, J.; Burkhonov, O.; Cooke, E.; de Diego, J. A.; Dhungana, G.; Farina, C.; Ferrante, F. V.; Flewelling, H. A.; Fox, O. D.; Fynbo, J.; Gehrels, N.; Georgiev, L.; González, J. J.; Greiner, J.; Güver, T.; Hartoog, O.; Hatch, N.; Jelinek, M.; Kehoe, R.; Klose, S.; Klunko, E.; Kopač, D.; Kutyrev, A.; Krugly, Y.; Lee, W. H.; Levan, A.; Linkov, V.; Matkin, A.; Minikulov, N.; Molotov, I.; Prochaska, J. X.; Richer, M. G.; Román-Zúñiga, C. G.; Rumyantsev, V.; Sánchez-Ramírez, R.; Steele, I.; Tanvir, N. R.; Volnova, A.; Watson, A. M.; Xu, D.; Yuan, F.

    2014-08-01

    We present optical and near-infrared (NIR) photometry for three gamma-ray burst supernovae (GRB-SNe): GRB 120729A, GRB 130215A/SN 2013ez, and GRB 130831A/SN 2013fu. For GRB 130215A/SN 2013ez, we also present optical spectroscopy at t - t0 = 16.1 d, which covers rest-frame 3000-6250 Å. Based on Fe ii λ5169 and Si ii λ6355, our spectrum indicates an unusually low expansion velocity of ~4000-6350 km s-1, the lowest ever measured for a GRB-SN. Additionally, we determined the brightness and shape of each accompanying SN relative to a template supernova (SN 1998bw), which were used to estimate the amount of nickel produced via nucleosynthesis during each explosion. We find that our derived nickel masses are typical of other GRB-SNe, and greater than those of SNe Ibc that are not associated with GRBs. For GRB 130831A/SN 2013fu, we used our well-sampled R-band light curve (LC) to estimate the amount of ejecta mass and the kinetic energy of the SN, finding that these too are similar to other GRB-SNe. For GRB 130215A, we took advantage of contemporaneous optical/NIR observations to construct an optical/NIR bolometric LC of the afterglow. We fit the bolometric LC with the millisecond magnetar model of Zhang & Mészáros (2001, ApJ, 552, L35), which considers dipole radiation as a source of energy injection to the forward shock powering the optical/NIR afterglow. Using this model we derive an initial spin period of P = 12 ms and a magnetic field of B = 1.1 × 1015 G, which are commensurate with those found for proposed magnetar central engines of other long-duration GRBs. Table 3 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568/A19

  1. Afterglow Organic Light-Emitting Diode.

    PubMed

    Kabe, Ryota; Notsuka, Naoto; Yoshida, Kou; Adachi, Chihaya

    2016-01-27

    An afterglow organic light-emitting diode (OLED) that displays electroluminescence with long transient decay after it is turned off is demonstrated. This OLED exhibits blue and green dual emission originating from fluorescence and phosphorescence, respectively. A phosphorescence lifetime of 4.3 s is achieved. PMID:26599764

  2. UNUSUAL CENTRAL ENGINE ACTIVITY IN THE DOUBLE BURST GRB 110709B

    SciTech Connect

    Zhang Binbin; Burrows, David N.; Meszaros, Peter; Falcone, Abraham D.; Zhang Bing; Wang Xiangyu; Stratta, Giulia; D'Elia, Valerio; Frederiks, Dmitry; Golenetskii, Sergey; Cummings, Jay R.; Barthelmy, Scott D.; Gehrels, Neil; Norris, Jay P.

    2012-04-01

    The double burst, GRB 110709B, triggered the Swift/Burst Alert Telescope (BAT) twice at 21:32:39 UT and 21:43:45 UT, respectively, on 2011 July 9. This is the first time we observed a gamma-ray burst (GRB) with two BAT triggers. In this paper, we present simultaneous Swift and Konus-WIND observations of this unusual GRB and its afterglow. If the two events originated from the same physical progenitor, their different time-dependent spectral evolution suggests they must belong to different episodes of the central engine, which may be a magnetar-to-BH accretion system.

  3. 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; Falcone, Abraham D.; Barthelmy, Scott D.; Gehrels, Neil

    2011-01-01

    The double burst, GRB 110709B, triggered Swift/BAT twice at 21:32:39 UT and 21:43:45 UT, respectively, on 9 July 2011. This is the first time we observed a GRB with two BAT triggers. In this paper, we present simultaneous Swift and Konus-WIND observations of this unusual GRB and its afterglow. If the two events are from the same physical origin, their different time-dependent spectral evolution suggest they must belong to different episodes of the central engine, which may be a magnetar-to-BH accretion system.

  4. Simulations of gamma-ray burst afterglows with a relativistic kinetic code

    NASA Astrophysics Data System (ADS)

    Pennanen, T.; Vurm, I.; Poutanen, J.

    2014-04-01

    Aims: This paper introduces a kinetic code that simulates gamma-ray burst (GRB) afterglow emission from the external forward shock and presents examples of some of its applications. One interesting research topic discussed in the paper is the high-energy radiation produced by Compton scattering of the prompt GRB photons against the shock-accelerated electrons. The difference between the forward shock emission in a wind-type and a constant-density medium is also studied, and the emission due to Maxwellian electron injection is compared to the case with pure power-law electrons. Methods: The code calculates the time-evolving photon and electron distributions in the emission region by solving the relativistic kinetic equations for each particle species. For the first time, the full relativistic equations for synchrotron emission/absorption, Compton scattering, and pair production/annihilation were applied to model the forward shock emission. The synchrotron self-absorption thermalization mechanism, which shapes the low-energy end of the electron distribution, was also included in the electron equation. Results: The simulation results indicate that inverse Compton scattering of the prompt GRB photons can produce a luminous ≳TeV emission component, even when pair production in the emission region is taken into account. This very high-energy radiation may be observable in low-redshift GRBs. The test simulations also show that the low-energy end of a pure power-law distribution of electrons can thermalize owing to synchrotron self-absorption in a wind-type environment, but without an observable impact on the radiation spectrum. Moreover, a flattening in the forward shock X-ray light curve may be expected when the electron injection function is assumed to be purely Maxwellian instead of a power law. The flux during such a flattening is likely to be lower than the Swift/XRT sensitivity in the case of a constant-density external medium, but a wind environment may result in

  5. GAMMA-RAY BURSTS IN THE FERMI ERA: THE SPECTRAL ENERGY DISTRIBUTION OF THE PROMPT EMISSION

    SciTech Connect

    Massaro, F.; Grindlay, J. E.; Paggi, A.

    2010-05-10

    Gamma-ray bursts (GRBs) show evidence of different light curves, duration, afterglows, and host galaxies and explode within a wide redshift range. However, their spectral energy distributions (SEDs) appear to be very similar, showing a curved shape. Band et al. proposed a phenomenological description of the integrated spectral shape for the GRB prompt emission, the so-called Band function. In this Letter, we suggest an alternative scenario to explain the curved shape of GRB SEDs: the log-parabolic model. In comparison with the Band spectral shape our model is statistically favored because it fits the GRB spectra with one parameter less than the Band function and is motivated by a theoretical acceleration scenario. The new Fermi observations of GRBs will be crucial for disentangling these two models.

  6. DIVERSITY OF SHORT GAMMA-RAY BURST AFTERGLOWS FROM COMPACT BINARY MERGERS HOSTING PULSARS

    SciTech Connect

    Holcomb, Cole; Ramirez-Ruiz, Enrico; De Colle, Fabio; Montes, Gabriela

    2014-07-20

    Short-duration gamma-ray bursts (sGRBs) are widely believed to result from the mergers of compact binaries. This model predicts an afterglow that bears the characteristic signatures of a constant, low-density medium, including a smooth prompt-afterglow transition, and a simple temporal evolution. However, these expectations are in conflict with observations for a non-negligible fraction of sGRB afterglows. In particular, the onset of the afterglow phase for some of these events appears to be delayed and, in addition, a few of them exhibit late-time rapid fading in their light curves. We show that these peculiar observations can be explained independently of ongoing central engine activity if some sGRB progenitors are compact binaries hosting at least one pulsar. The Poynting flux emanating from the pulsar companion can excavate a bow-shock cavity surrounding the binary. If this cavity is larger than the shock deceleration length scale in the undisturbed interstellar medium, then the onset of the afterglow will be delayed. Should the deceleration occur entirely within the swept-up thin shell, a rapid fade in the light curve will ensue. We identify two types of pulsar that can achieve the conditions necessary for altering the afterglow: low-field, long-lived pulsars, and high-field pulsars. We find that a sizable fraction (≈20%-50%) of low-field pulsars are likely to reside in neutron star binaries based on observations, while their high-field counterparts are not. Hydrodynamical calculations motivated by this model are shown to be in good agreement with observations of sGRB afterglow light curves.

  7. IS THE LATE NEAR-INFRARED BUMP IN SHORT-HARD GRB 130603B DUE TO THE LI-PACZYNSKI KILONOVA?

    SciTech Connect

    Jin, Zhi-Ping; Fan, Yi-Zhong; Wei, Da-Ming; Xu, Dong; Wu, Xue-Feng

    2013-09-20

    Short-hard gamma-ray bursts (GRBs) are widely believed to be produced by the merger of two binary compact objects, specifically by two neutron stars or by a neutron star orbiting a black hole. According to the Li-Paczynski kilonova model, the merger would launch sub-relativistic ejecta and a near-infrared/optical transient would then occur, lasting up to days, which is powered by the radioactive decay of heavy elements synthesized in the ejecta. The detection of a late bump using the Hubble Space Telescope (HST) in the near-infrared afterglow light curve of the short-hard GRB 130603B is indeed consistent with such a model. However, as shown in this Letter, the limited HST near-infrared light curve behavior can also be interpreted as the synchrotron radiation of the external shock driven by a wide mildly relativistic outflow. In such a scenario, the radio emission is expected to peak with a flux of ∼100 μJy, which is detectable for current radio arrays. Hence, the radio afterglow data can provide complementary evidence on the nature of the bump in GRB 130603B. It is worth noting that good spectroscopy during the bump phase in short-hard bursts can test the validity of either model above, analogous to spectroscopy of broad-lined Type Ic supernova in long-soft GRBs.

  8. ALMA SUBMILLIMETER CONTINUUM IMAGING OF THE HOST GALAXIES OF GRB 021004 AND GRB 080607

    SciTech Connect

    Wang, Wei-Hao; Huang, Kui-Yun; Chen, Hsiao-Wen

    2012-12-20

    We report 345 GHz continuum observations of the host galaxies of gamma-ray bursts (GRBs) 021004 and 080607 at z > 2 using the Atacama Large Millimeter/Submillimeter Array (ALMA) in Cycle 0. Of the two bursts, GRB 021004 is one of the few GRBs that originate in a Lyman limit host, while GRB 080607 is classified as a 'dark burst' and its host galaxy is a candidate of dusty star-forming galaxy at z {approx} 3. With an order of magnitude improvement in the sensitivities of the new imaging searches, we detect the host galaxy of GRB 080607 with a flux of S{sub 345} = 0.31 {+-} 0.09 mJy and a corresponding infrared luminosity of L{sub IR} = (2.4-4.5) Multiplication-Sign 10{sup 11} L{sub Sun }. However, the host galaxy of GRB 021004 remains undetected and the ALMA observations allow us to place a 3{sigma} upper limit of L{sub IR} < 3.1 Multiplication-Sign 10{sup 11} L{sub Sun} for the host galaxy. The continuum imaging observations show that the two galaxies are not ultraluminous infrared galaxies, but are at the faintest end of the dusty galaxy population that gives rise to the submillimeter extragalactic background light. The derived star formation rates of the two GRB host galaxies are less than 100 M{sub Sun} yr{sup -1}, which are broadly consistent with optical measurements. The result suggests that the large extinction (A{sub V} {approx} 3) in the afterglow of GRB 080607 is confined along its particularly dusty sight line, and not representative of the global properties of the host galaxy.

  9. Closing in on a Short-Hard Burst Progenitor: Constraints From Early-Time Optical Imaging and Spectroscopy of a Possible Host Galaxy of GRB 050509b

    SciTech Connect

    Bloom, Joshua S.; Prochaska, J.X.; Pooley, D.; Blake, C.W.; Foley, R.J.; Jha, S.; Ramirez-Ruiz, E.; Granot, J.; Filippenko, A.V.; Sigurdsson, S.; Barth, A.J.; Chen, H.-W.; Cooper, M.C.; Falco, E.E.; Gal, R.R.; Gerke, B.F.; Gladders, M.D.; Greene, J.E.; Hennanwi, J.; Ho, L.C.; Hurley, K.; /UC, Berkeley, Astron. Dept. /Lick Observ. /Harvard-Smithsonian Ctr. Astrophys. /Princeton, Inst. Advanced Study /KIPAC, Menlo Park /Penn State U., Astron. Astrophys. /UC, Irvine /MIT, MKI /UC, Davis /UC, Berkeley /Carnegie Inst. Observ. /UC, Berkeley, Space Sci. Dept. /Michigan U. /LBL, Berkeley /Spitzer Space Telescope

    2005-06-07

    The localization of the short-duration, hard-spectrum gamma-ray burst GRB050509b by the Swift satellite was a watershed event. Never before had a member of this mysterious subclass of classic GRBs been rapidly and precisely positioned in a sky accessible to the bevy of ground-based follow-up facilities. Thanks to the nearly immediate relay of the GRB position by Swift, we began imaging the GRB field 8 minutes after the burst and have continued during the 8 days since. Though the Swift X-ray Telescope (XRT) discovered an X-ray afterglow of GRB050509b, the first ever of a short-hard burst, thus far no convincing optical/infrared candidate afterglow or supernova has been found for the object. We present a re-analysis of the XRT afterglow and find an absolute position of R.A. = 12h36m13.59s, Decl. = +28{sup o}59'04.9'' (J2000), with a 1{sigma} uncertainty of 3.68'' in R.A., 3.52'' in Decl.; this is about 4'' to the west of the XRT position reported previously. Close to this position is a bright elliptical galaxy with redshift z = 0.2248 {+-} 0.0002, about 1' from the center of a rich cluster of galaxies. This cluster has detectable diffuse emission, with a temperature of kT = 5.25{sub -1.68}{sup +3.36} keV. We also find several ({approx}11) much fainter galaxies consistent with the XRT position from deep Keck imaging and have obtained Gemini spectra of several of these sources. Nevertheless we argue, based on positional coincidences, that the GRB and the bright elliptical are likely to be physically related. We thus have discovered reasonable evidence that at least some short-duration, hard-spectra GRBs are at cosmological distances. We also explore the connection of the properties of the burst and the afterglow, finding that GRB050509b was underluminous in both of these relative to long-duration GRBs. However, we also demonstrate that the ratio of the blast-wave energy to the {gamma}-ray energy is consistent with that of long-duration GRBs. We thus find plausible

  10. Toward a Better Understanding of the GRB Phenomenon: a New Model for GRB Prompt Emission and its Effects on the New LiNT- Epeak,irest,NT Relation

    NASA Astrophysics Data System (ADS)

    Guiriec, S.; Kouveliotou, C.; Daigne, F.; Zhang, B.; Hascoët, R.; Nemmen, R. S.; Thompson, D. J.; Bhat, P. N.; Gehrels, N.; Gonzalez, M. M.; Kaneko, Y.; McEnery, J.; Mochkovitch, R.; Racusin, J. L.; Ryde, F.; Sacahui, J. R.; Ünsal, A. M.

    2015-07-01

    Gamma-ray burst (GRB) prompt emission spectra in the keV-MeV energy range are usually considered to be adequately fitted with the empirical Band function. Recent observations with the Fermi Gamma-ray Space Telescope (Fermi) revealed deviations from the Band function, sometimes in the form of an additional blackbody (BB) component, while on other occasions in the form of an additional power law (PL) component extending to high energies. In this article we investigate the possibility that the three components may be present simultaneously in the prompt emission spectra of two very bright GRBs (080916C and 090926A) observed with Fermi, and how the three components may affect the overall shape of the spectra. While the two GRBs are very different when fitted to a single Band function, they look like “twins” in the three-component scenario. Through fine-time spectroscopy down to the 100 ms timescale, we follow the evolution of the various components. We succeed in reducing the number of free parameters in the three-component model, which results in a new semi-empirical model—but with physical motivations—to be competitive with the Band function in terms of number of degrees of freedom. From this analysis using multiple components, the Band function is globally the most intense component, although the additional PL can overpower the others in sharp time structures. The Band function and the BB component are the most intense at early times and globally fade across the burst duration. The additional PL is the most intense component at late time and may be correlated with the extended high-energy emission observed thousands of seconds after the burst with Fermi/Large Area Telescope. Unexpectedly, this analysis also shows that the additional PL may be present from the very beginning of the burst, where it may even overpower the other components at low energy. We investigate the effect of the three components on the new time-resolved luminosity-hardness relation in

  11. Afterglow Radiation from Gamma Ray Bursts

    SciTech Connect

    Desmond, Hugh; /Leuven U. /SLAC

    2006-08-28

    Gamma-ray bursts (GRB) are huge fluxes of gamma rays that appear randomly in the sky about once a day. It is now commonly accepted that GRBs are caused by a stellar object shooting off a powerful plasma jet along its rotation axis. After the initial outburst of gamma rays, a lower intensity radiation remains, called the afterglow. Using the data from a hydrodynamical numerical simulation that models the dynamics of the jet, we calculated the expected light curve of the afterglow radiation that would be observed on earth. We calculated the light curve and spectrum and compared them to the light curves and spectra predicted by two analytical models of the expansion of the jet (which are based on the Blandford and McKee solution of a relativistic isotropic expansion; see Sari's model [1] and Granot's model [2]). We found that the light curve did not decay as fast as predicted by Sari; the predictions by Granot were largely corroborated. Some results, however, did not match Granot's predictions, and more research is needed to explain these discrepancies.

  12. 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.

  13. Black Hole Physics and Astrophysics: The GRB-Supernova Connection and URCA-1 - URCA-2

    NASA Astrophysics Data System (ADS)

    Ruffini, R.; Bernardini, M. G.; Bianco, C. L.; Vitagliano, L.; Xue, S.-S.; Chardonnet, P.; Fraschetti, F.; Gurzadyan, V.

    2006-02-01

    We outline the confluence of three novel theoretical fields in our modeling of Gamma-Ray Bursts (GRBs): 1) the ultrarelativistic regime of a shock front expanding with a Lorentz gamma factor ~ 300; 2) the quantum vacuum polarization process leading to an electron-positron plasma originating the shock front; and 3) the general relativistic process of energy extraction from a black hole originating the vacuum polarization process. There are two different classes of GRBs: the long GRBs and the short GRBs. We here address the issue of the long GRBs. The theoretical understanding of the long GRBs has led to the detailed description of their luminosities in fixed energy bands, of their spectral features and made also possible to probe the astrophysical scenario in which they originate. We are specially interested, in this report, to a subclass of long GRBs which appear to be accompanied by a supernova explosion. We are considering two specific examples: GRB980425/SN1998bw and GRB030329/SN2003dh. While these supernovae appear to have a standard energetics of 1049 ergs, the GRBs are highly variable and can have energetics 104 - 105 times larger than the ones of the supernovae. Moreover, many long GRBs occurs without the presence of a supernova. It is concluded that in no way a GRB can originate from a supernova. The precise theoretical understanding of the GRB luminosity we present evidence, in both these systems, the existence of an independent component in the X-ray emission, usually interpreted in the current literature as part of the GRB afterglow. This component has been observed by Chandra and XMM to have a strong decay on scale of months. We have named here these two sources respectively URCA-1 and URCA-2, in honor of the work that George Gamow and Mario Shoenberg did in 1939 in this town of Urca identifying the basic mechanism, the Urca processes, leading to the process of gravitational collapse and the formation of a neutron star and a supernova. The further

  14. MULTI-WAVELENGTH AFTERGLOWS OF FAST RADIO BURSTS

    SciTech Connect

    Yi, Shuang-Xi; Gao, He; Zhang, Bing

    2014-09-01

    The physical origin of fast radio bursts (FRBs) is unknown. Detecting electromagnetic counterparts to FRBs in other wavelengths is essential to measure their distances and to determine their physical origin. Assuming that at least some of them are of cosmological origin, we calculate their afterglow light curves in multiple wavelengths (X-rays, optical, and radio) by assuming a range of total kinetic energies and redshifts. We focus on forward shock emission, but also consider the possibility that some of the FRBs might have bright reverse shock emission. In general, FRB afterglows are too faint to be detected by current detectors. Only if an FRB has a very low radiative efficiency in radio (hence, a very large kinetic energy), and when it is close enough to observe can its afterglow be detected in the optical and radio bands. We discuss observational strategies for detecting these faint afterglows using future telescopes such as Large Synoptic Survey Telescope and Expanded Very Large Array.

  15. Comparison of Three Afterglow Morphologies

    SciTech Connect

    Salmonson, J D; Rossi, E; Lazzati, D

    2003-12-23

    Herein we compare three functional families for afterglow morphologies: the homogeneous afterglow with constant shock surface energy density, the structured afterglow for which the energy density decays as a power-law as a function of viewer angle, and the gaussian afterglow which has an exponential decay of energy density with viewer angle. We simulate observed lightcurves and polarization curves for each as seen from a variety of observer vantage points. We find that the homogeneous jet is likely inconsistent with observations and suggest that the future debate on the structure of afterglow jets will be between the other two candidates.

  16. ON THE ORIGIN OF > 10 GeV PHOTONS IN GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Wang Xiangyu; Liu Ruoyu; Lemoine, Martin

    2013-07-10

    Fermi/LAT has detected long-lasting high-energy photons (>100 MeV) from gamma-ray bursts (GRBs), with the highest energy photons reaching about 100 GeV. One proposed scenario is that they are produced by high-energy electrons accelerated in GRB forward shocks via synchrotron radiation. We study the maximum synchrotron photon energy in this scenario, considering the properties of the microturbulence magnetic fields behind the shock, as revealed by recent particle-in-cell simulations and theoretical analyses of relativistic collisionless shocks. Due to the small-scale nature of the microturbulent magnetic field, the Bohm acceleration approximation, in which the scattering mean free path is equal to the particle Larmor radius, breaks down at such high energies. This effect leads to a typical maximum synchrotron photon of a few GeV at 100 s after the burst and this maximum synchrotron photon energy decreases quickly with time. We show that the fast decrease of the maximum synchrotron photon energy leads to a fast decay of the synchrotron flux. The 10-100 GeV photons detected after the prompt phase cannot be produced by the synchrotron mechanism. They could originate from the synchrotron self-Compton emission of the early afterglow if the circumburst density is sufficiently large, or from the external inverse Compton process in the presence of central X-ray emission, such as X-ray flares and prompt high-latitude X-ray emission.

  17. Afterglow model for the radio emission from the jetted tidal disruption candidate Swift J1644+57

    NASA Astrophysics Data System (ADS)

    Metzger, Brian D.; Giannios, Dimitrios; Mimica, Petar

    2012-03-01

    The recent transient event Swift J1644+57 has been interpreted as emission from a collimated relativistic jet, powered by the sudden onset of accretion on to a supermassive black hole following the tidal disruption of a star. Here we model the radio-microwave emission as synchrotron radiation produced by the shock interaction between the jet and the gaseous circumnuclear medium (CNM). At early times after the onset of the jet (t≲ 5-10 d) a reverse shock propagates through and decelerates the ejecta, while at later times the outflow approaches the Blandford-McKee self-similar evolution (possibly modified by additional late energy injection). The achromatic break in the radio light curve of Swift J1644+57 is naturally explained as the transition between these phases. We show that the temporal indices of the pre- and post-break light curve are consistent with those predicted if the CNM has a wind-type radial density profile n∝r-2. The observed synchrotron frequencies and self-absorbed flux constrain the fraction of the post-shock thermal energy in relativistic electrons ɛe≈ 0.03-0.1, the CNM density at 1018 cm n18≈ 1-10 cm-3 and the initial Lorentz factor Γj≈ 10-20 and opening angle ? of the jet. Radio modelling thus provides robust independent evidence for a narrowly collimated outflow. Extending our model to the future evolution of Swift J1644+57, we predict that the radio flux at low frequencies (ν≲ few GHz) will begin to brighten more rapidly once the characteristic frequency νm crosses below the radio band after it decreases below the self-absorption frequency on a time-scale of months (indeed, such a transition may already have begun). Our results demonstrate that relativistic outflows from tidal disruption events provide a unique probe of the conditions in distant, previously inactive galactic nuclei, complementing studies of normal active galactic nuclei.

  18. The dark nature of GRB 130528A and its host galaxy

    NASA Astrophysics Data System (ADS)

    Jeong, S.; Castro-Tirado, A. J.; Bremer, M.; Winters, J. M.; Gorosabel, J.; Guziy, S.; Pandey, S. B.; Jelínek, M.; Sánchez-Ramírez, R.; Sokolov, Ilya V.; Orekhova, N. V.; Moskvitin, A. S.; Tello, J. C.; Cunniffe, R.; Lara-Gil, O.; Oates, S. R.; Pérez-Ramírez, D.; Bai, J.; Fan, Y.; Wang, C.; Park, I. H.

    2014-09-01

    Aims: We study the dark nature of GRB 130528A through multi-wavelength observations and conclude that the main reason for the optical darkness is local extinction inside of the host galaxy. Methods: Automatic observations were performed at the Burst Optical Observer and Transient Exploring System (BOOTES)-4/MET robotic telescope. We also triggered target of opportunity (ToO) observations at Observatorio de Sierra Nevada (OSN), IRAM Plateau de Bure Interferometer (PdBI) and Gran Telescopio Canarias (GTC + OSIRIS). The host galaxy photometric observations in optical to near-infrared (nIR) wavelengths were achieved through large ground-based aperture telescopes, such as 10.4 m Gran Telescopio Canarias (GTC), 4.2 m William Herschel Telescope (WHT), 6 m Bolshoi Teleskop Alt-azimutalnyi (BTA) telescope, and 2 m Liverpool Telescope (LT). Based on these observations, spectral energy distributions (SED) for the host galaxy and afterglow were constructed. Results: Thanks to millimetre (mm) observations at PdBI, we confirm the presence of a mm source within the XRT error circle that faded over the course of our observations and identify the host galaxy. However, we do not find any credible optical source within early observations with BOOTES-4/MET and 1.5 m OSN telescopes. Spectroscopic observation of this galaxy by GTC showed a single faint emission line that likely corresponds to [OII] 3727 Å at a redshift of 1.250 ± 0.001, implying a star formation rate (M⊙/yr) > 6.18 M⊙/yr without correcting for dust extinction. The probable line-of-sight extinction towards GRB 130528A is revealed through analysis of the afterglow SED, resulting in a value of A^GRBV≥ 0.9 at the rest frame; this is comparable to extinction levels found among other dark GRBs. The SED of the host galaxy is explained well (χ2/d.o.f. = 0.564) by a luminous (MB = -21.16), low-extinction (AV = 0, rest frame), and aged (2.6 Gyr) stellar population. We can explain this apparent contradiction in global and

  19. A tale of two GRB-SNe at a common redshift of z=0.54

    NASA Astrophysics Data System (ADS)

    Cano, Z.; Bersier, D.; Guidorzi, C.; Margutti, R.; Svensson, K. M.; Kobayashi, S.; Melandri, A.; Wiersema, K.; Pozanenko, A.; van der Horst, A. J.; Pooley, G. G.; Fernandez-Soto, A.; Castro-Tirado, A. J.; Postigo, A. De Ugarte; Im, M.; Kamble, A. P.; Sahu, D.; Alonso-Lorite, J.; Anupama, G.; Bibby, J. L.; Burgdorf, M. J.; Clay, N.; Curran, P. A.; Fatkhullin, T. A.; Fruchter, A. S.; Garnavich, P.; Gomboc, A.; Gorosabel, J.; Graham, J. F.; Gurugubelli, U.; Haislip, J.; Huang, K.; Huxor, A.; Ibrahimov, M.; Jeon, Y.; Jeon, Y.-B.; Ivarsen, K.; Kasen, D.; Klunko, E.; Kouveliotou, C.; Lacluyze, A.; Levan, A. J.; Loznikov, V.; Mazzali, P. A.; Moskvitin, A. S.; Mottram, C.; Mundell, C. G.; Nugent, P. E.; Nysewander, M.; O'Brien, P. T.; Park, W.-K.; Peris, V.; Pian, E.; Reichart, D.; Rhoads, J. E.; Rol, E.; Rumyantsev, V.; Scowcroft, V.; Shakhovskoy, D.; Small, E.; Smith, R. J.; Sokolov, V. V.; Starling, R. L. C.; Steele, I.; Strom, R. G.; Tanvir, N. R.; Tsapras, Y.; Urata, Y.; Vaduvescu, O.; Volnova, A.; Volvach, A.; Wijers, R. A. M. J.; Woosley, S. E.; Young, D. R.

    2011-05-01

    We present ground-based and Hubble Space Telescope optical observations of the optical transients (OTs) of long-duration Gamma Ray Bursts (GRBs) 060729 and 090618, both at a redshift of z= 0.54. For GRB 060729, bumps are seen in the optical light curves (LCs), and the late-time broad-band spectral energy distributions (SEDs) of the OT resemble those of local Type Ic supernovae (SNe). For GRB 090618, the dense sampling of our optical observations has allowed us to detect well-defined bumps in the optical LCs, as well as a change in colour, that are indicative of light coming from a core-collapse SN. The accompanying SNe for both events are individually compared with SN1998bw, a known GRB supernova, and SN1994I, a typical Type Ic supernova without a known GRB counterpart, and in both cases the brightness and temporal evolution more closely resemble SN1998bw. We also exploit our extensive optical and radio data for GRB 090618, as well as the publicly available Swift-XRT data, and discuss the properties of the afterglow at early times. In the context of a simple jet-like model, the afterglow of GRB 090618 is best explained by the presence of a jet-break at t-to > 0.5 d. We then compare the rest-frame, peak V-band absolute magnitudes of all of the GRB and X-Ray Flash (XRF)-associated SNe with a large sample of local Type Ibc SNe, concluding that, when host extinction is considered, the peak magnitudes of the GRB/XRF-SNe cannot be distinguished from the peak magnitudes of non-GRB/XRF SNe.

  20. The air afterglow revisited

    NASA Technical Reports Server (NTRS)

    Kaufman, F.

    1972-01-01

    The air afterglow, 0 + NO2 chemiluminescence, is discussed in terms of fluorescence, photodissociation, and quantum theoretical calculations of NO2. The experimental results presented include pressure dependence, M-dependence, spectral dependence of P and M, temperature dependence, and infrared measurements. The NO2 energy transfer model is also discussed.

  1. Methodology in the Afterglow

    ERIC Educational Resources Information Center

    Hofsess, Brooke Anne

    2013-01-01

    My dissertation study seeks to understand how artist-teacher renewal may be nurtured through aesthetic experiential play in a Masters of Art Education degree program, and beyond, as my former students/participants and myself experience finding ourselves in its afterglow. "Aesthetic experiential play" could be described as a playful,…

  2. Applying an accurate spherical model to gamma-ray burst afterglow observations

    NASA Astrophysics Data System (ADS)

    Leventis, K.; van der Horst, A. J.; van Eerten, H. J.; Wijers, R. A. M. J.

    2013-05-01

    We present results of model fits to afterglow data sets of GRB 970508, GRB 980703 and GRB 070125, characterized by long and broad-band coverage. The model assumes synchrotron radiation (including self-absorption) from a spherical adiabatic blast wave and consists of analytic flux prescriptions based on numerical results. For the first time it combines the accuracy of hydrodynamic simulations through different stages of the outflow dynamics with the flexibility of simple heuristic formulas. The prescriptions are especially geared towards accurate description of the dynamical transition of the outflow from relativistic to Newtonian velocities in an arbitrary power-law density environment. We show that the spherical model can accurately describe the data only in the case of GRB 970508, for which we find a circumburst medium density n ∝ r-2. We investigate in detail the implied spectra and physical parameters of that burst. For the microphysics we show evidence for equipartition between the fraction of energy density carried by relativistic electrons and magnetic field. We also find that for the blast wave to be adiabatic, the fraction of electrons accelerated at the shock has to be smaller than 1. We present best-fitting parameters for the afterglows of all three bursts, including uncertainties in the parameters of GRB 970508, and compare the inferred values to those obtained by different authors.

  3. Infrared and Optical Observations of GRB 030115 and its Extremely Red Host Galaxy: Implications for Dark Bursts

    NASA Technical Reports Server (NTRS)

    Levan, Andrew; Fruchter, Andrew; Rhoads, James; Mobasher, Bahram; Tanvir, Nial; Gorosabel, Javier; Rol, Evert; Kouveliotou, Chryssa; DellAntonio, Ian; Merrill, Javier

    2004-01-01

    We present near-infrared (a) and optical observations of the afterglow of GRB 030115. Discovered in an infrared search at Kitt Peak 5 hours after the burst trigger, this afterglow is the faintest ever observed in the R-band at such an early epoch, and exhibits very red colors, with R-K approximately equal to 6. The magnitude of the optical afterglow of GRB 030115 is fainter than many upper limits for other bursts, suggesting that without early nIR observations it would have been classified as a "dark" burst. Both the color and optical magnitude of the afterglow are likely due to dust extinction and indicate that at least some optical afterglows are observations were also taken of the host galaxy and the surrounding field. Photometric redshifts imply that the host, and a substantial number of faint galaxies in the field are at z approximately 2.5. The overdensity of galaxies is sufficiently great that GRB 030115 may have occurred in a rich high-redshift cluster. The host galaxy shows extremely red colors (R-K=5) and is the first GRB host to be classified as an Extreme Red Object (ERO). Some of the galaxies surrounding the host also show very red colors, while the majority of the cluster are much bluer, indicating ongoing unobscured star formation. As it is thought that much of high redshift star formation occurs in highly obscured environments it may well be that GRB 030115 represents a transition object, between the relatively unobscured afterglows seen to date and a population which are very heavily extinguished, even in the nIR.

  4. Iron lines in the X-ray afterglows of Gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Piro, L.

    1998-12-01

    X-ray measurements of iron lines can provide a powerful diagnostics of the environment of Gamma-ray bursts, thus enlightening the still misterious nature of the central engine powering these phenomena. Furthermore, they would allow a direct measurement of the distance of the GRB, bypassing completely the long chain of steps that, from the Gamma and X-ray localization, brings to the optical determination of the redshift. In this contribution we will present the results of a search of this feature in the BeppoSAX X-ray afterglows of GRB. We will discuss their implication for near future missions, as AXAF and XMM.

  5. Radio and X-ray observations of the Ultra-long GRB 150518A

    NASA Astrophysics Data System (ADS)

    Johnson, Louis; Kamble, Atish; Margutti, Raffaella; Soderberg, Alicia Margarita; Supernova Forensics

    2016-01-01

    Gamma Ray Burst (GRB) 150518A, discovered on 2015 May 18 by the MAXI and KONUS-Wind satellites, lasted for about 1000s, making it an important addition to the recently established class of very long duration GRBs. We report on the JVLA radio observations of the afterglow of GRB 150518A. Additionally, we report the analysis of Xray afterglow observations by Swift-XRT. Multi-band light curves of the radio afterglow display an unusual, conspicuous rise around 10 days after the burst, possibly due to enhanced mass-loss from the progenitor in the final stages of evolution before the GRB. The X-ray afterglow spectrum is significantly soft (photon index Γx > 3) and heavily absorbed (NHx,i > 8 × 10^{21}/cm^2). These properties suggest peculiar behavior that is different from the predictions of the standard fireball model of GRBs. In the light of these properties, we compare different models of progenitors for very long duration GRBs. This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  6. GRB070125: The First Long-Duration Gamma-Ray Burst in a Halo Environment

    NASA Technical Reports Server (NTRS)

    Bradley, Cenko S.; Fox, Derek B.; Penprase, Brian E.; Kulkarni, Shri R.; Price, Paul A.; Berger, Edo; Kulkarni, Shri R.; Harrison, Fiona A.; Gal-Yam, Avishay; Ofek, Eran O.; Rau, Arne; Chandra, Poonam; Frail, Dale A.; Kasliwal, Mansi M.; Schmidt, Brian P.; Soderberg, Alicia M.; Cameron, P. Brian; Roth, Kathy C.

    2007-01-01

    We present the discovery and high signal-to-noise spectroscopic observations of the optical afterglow of the long-duration gamma-ray burst GRB070125. Unlike all previously observed long-duration afterglows in the redshift range 0.5 < z < 2.0, we find no strong (rest-frame equivalent width W > 1.0 A) absorption features in the wavelength range 4000 - 10000 A. The sole significant feature is a weak doublet we identify as Mg 11 2796 (W = 0.18 +/- 0.02 A), 2803 (W = 0.08 +0I.-01 ) at z = 1.5477 +/- 0.0001. The low observed Mg II and inferred H I column densities are typically observed in galactic halos, far away from the bulk of massive star formation. Deep ground-based imaging reveals no host directly underneath the afterglow to a limit of R > 25.4 mag. Either of the two nearest blue galaxies could host GRB070125; the large offset (d >= 27 kpc) would naturally explain the low column density. To remain consistent with the large local (i.e. parsec scale) circum-burst density inferred from broadband afterglow observations, we speculate GRB070125 may have occurred far away from the disk of its host in a compact star-forming cluster. Such distant stellar clusters, typically formed by dynamical galaxy interactions, have been observed in the nearby universe, and should be more prevalent at z>l where galaxy mergers occur more frequently.

  7. GRB090510: a short bright and hard GRB detected by Fermi

    SciTech Connect

    Palma, F. de

    2010-03-26

    On 2009 May 10, 00:22:59 UT (T{sub 0}) the Fermi Gamma-ray Burst Monitor (GBM) triggered and located the short and very bright GRB090510. For the first time, this hard GRB, with an Epeak of few MeV, also triggered independently the Fermi Large Area Telescope (LAT). Swift detected this GRB and the accurate position provided by the Swift/UVOT made possible a spectroscopic redshift measurement of z = 0.903 with VLT/FORS2. This short GRB exhibits new features for this kind of events such an extra component (power-law) at high energies and a long lasting (few minutes) emission observed by the LAT. These observations allow the derivation of very important physical parameters such as the minimum value of the bulk Lorentz factor and they put some unprecedent limits on the dependence of the speed of photons on their energy.

  8. Analytically useful spectra excited in an atmospheric pressure active nitrogen afterglow

    SciTech Connect

    Rice, G.W.; D'Silva, A.P.; Fassel, V.A.

    1984-03-01

    An atmospheric pressure active nitrogen (APAN) discharge has been utilized for producing characteristic molecular emissions from nonmetallic species introduced into the afterglow region of the discharge. The addition of inorganic S-, P-, B-, Cl-, and Br-containing compounds into the afterglow has resulted in the formation of excited S/sub 2/, PN, BO, NCl, and NBr species, respectively. Intense molecular Br/sub 2/ emission and I/sub 2/ emission, as well as atomic I emission, have also been observed. Preliminary analytical utilization of the molecular or atomic emissions observed revealed that the APAN afterglow may serve as a potentially useful detector for the aforementioned elements.

  9. The high-redshift gamma-ray burst GRB 140515A. A comprehensive X-ray and optical study

    NASA Astrophysics Data System (ADS)

    Melandri, A.; Bernardini, M. G.; D'Avanzo, P.; Sánchez-Ramírez, R.; Nappo, F.; Nava, L.; Japelj, J.; de Ugarte Postigo, A.; Oates, S.; Campana, S.; Covino, S.; D'Elia, V.; Ghirlanda, G.; Gafton, E.; Ghisellini, G.; Gnedin, N.; Goldoni, P.; Gorosabel, J.; Libbrecht, T.; Malesani, D.; Salvaterra, R.; Thöne, C. C.; Vergani, S. D.; Xu, D.; Tagliaferri, G.

    2015-09-01

    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 xHI ≤ 0.002. The spectral absorption lines detected for this event are the weakest lines ever observed in GRB afterglows, suggesting that GRB 140515A exploded in 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. 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. Based on observations collected at the European Southern Observatory, ESO, the VLT/Kueyen telescope, Paranal, Chile (proposal code: 093.A-0069), on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias (programme 49-008), and on observations made with the Italian 3.6-m Telescopio Nazionale Galileo (TNG), operated by the Fundación Galileo Galilei of the INAF (Instituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias (programme A26TAC_63).Appendix A is available in electronic form at

  10. Discovery of an Afterglow Extension of the Prompt Phase of Two Gamma Ray Bursts Observed by Swift

    NASA Technical Reports Server (NTRS)

    Bathelmy, S. D.; Cannizzo, J. K.; Gehrels, N.; Cusumano, G.; OBrien, P. T.; Vaughan, S.; Zhang, B.; Burrows, D. N.; Campana, S.; Chincarini, G.

    2005-01-01

    Contemporaneous BAT and XRT observations of two recent well-covered GRBs observed by Swift, GRB 050315 and GRB 050319, show clearly a prompt component joining the onset of the afterglow emission. The rapid slewing capability of the spacecraft enables X-ray observations immediately after the burst, typically 100 s following the initiation of the prompt y-ray phase. By fitting a power law form to the y-ray spectrum, we extrapolate the time dependent fluxes measured by the BAT, in the energy band 15 - 350 keV, into the spectral regime observed by the XRT 0.2 - 10 keV, and examine the functional form of the rate of decay of the two light curves. We find that the BAT and XRT light curves merge to form a unified curve. There is a period of steep decay up to 300 s, followed by a flatter decay. The duration of the steep decay, 100 s in the source frame after correcting for cosmological time dilation, agrees roughly with a theoretical estimate for the deceleration time of the relativistic ejecta as it interacts with circumstellar material. For GRB 050315, the steep decay can be characterized by an exponential form, where one e-folding decay time Te (BAT) = 24 f 2 s, and Te,(XRT) = 35 f 2 s. For GRB 050319, a power law decay - d l n f / d l n t = n, where n approx. = 3, provides a reasonable fit. The early time X-ray fluxes are consistent with representing the lower energy tail of the prompt emission, and provide our first quantitative measure of the decay of the prompt y-ray emission over a large dynamic range in flux. The initial steep decay is expected due to the delayed high latitude photons from a curved shell of relativistic plasma illuminated only for a short interval. The overall conclusion is that the prompt phase of GRBs remains observable for hundreds of seconds longer than previously thought.

  11. Chemical abundances associated with gamma-ray bursts: nucleosynthesis in afterglows

    NASA Astrophysics Data System (ADS)

    Hu, Tao; Wang, Min

    2014-03-01

    Gamma-ray burst (GRB) ejecta carries huge amounts of energy expanding into the surrounding medium and heats up these materials, making it possible that nucleosynthesis can take place in such hot sites in afterglow stage. Here, we study possible changes in chemical abundances in the GRB afterglow processes of Wolf-Rayet (WR) star wind environments (Case A) and constant density surroundings (Case B). We find that the light element of lithium-beryllium-boron could occur in the afterglows via He+He process and spallation reactions. Some isotopes of F, Ne, Mg, Al, Si, P, S and Fe-group elements are also new species formed in the afterglows via proton-, neutron- and α-capture. The results show that the nucleosynthetic yields might be a diagnostic of the GRB's ambient environment. Our calculations indicate that Mg, Al, Si, P, Cr, Mn, Fe and Co have trended to appear in Case A, while Ne, Ti and Ni trend to occur in Case B. Furthermore, although some species have occurred both in Cases A and B, their mass fractions are quite different in these two cases. Here, we show that the mass fractions of 7Li, 7Be, 24Mg and 30Si are higher in Case A than that in Case B, but 18F gives an opposite conclusion. Nucleosynthetic outputs might also be an indice to estimate the luminosity-temperature relation factor β. In this study, when β reduces, the mass abundances of 11B and 20Ne are higher in Case B than that in Case A; in contrast, as the β becomes larger, this trend would be reversed; therefore, perhaps we could select the above elements as the indicators to estimate the properties of the surroundings around the GRBs. We also suggest that the spectroscopic observations of a GRB afterglow could only reveal the nucleosynthetic outputs from the interaction site between the GRB jet and its ambient matter, but could not represent the original composition of the pre-GRB surrounding medium.

  12. A photometric redshift of z = 6.39 +/- 0.12 for GRB 050904.

    PubMed

    Haislip, J B; Nysewander, M C; Reichart, D E; Levan, A; Tanvir, N; Cenko, S B; Fox, D B; Price, P A; Castro-Tirado, A J; Gorosabel, J; Evans, C R; Figueredo, E; MacLeod, C L; Kirschbrown, J R; Jelinek, M; Guziy, S; de Ugarte Postigo, A; Cypriano, E S; LaCluyze, A; Graham, J; Priddey, R; Chapman, R; Rhoads, J; Fruchter, A S; Lamb, D Q; Kouveliotou, C; Wijers, R A M J; Bayliss, M B; Schmidt, B P; Soderberg, A M; Kulkarni, S R; Harrison, F A; Moon, D S; Gal-Yam, A; Kasliwal, M M; Hudec, R; Vitek, S; Kubanek, P; Crain, J A; Foster, A C; Clemens, J C; Bartelme, J W; Canterna, R; Hartmann, D H; Henden, A A; Klose, S; Park, H-S; Williams, G G; Rol, E; O'Brien, P; Bersier, D; Prada, F; Pizarro, S; Maturana, D; Ugarte, P; Alvarez, A; Fernandez, A J M; Jarvis, M J; Moles, M; Alfaro, E; Ivarsen, K M; Kumar, N D; Mack, C E; Zdarowicz, C M; Gehrels, N; Barthelmy, S; Burrows, D N

    2006-03-01

    Gamma-ray bursts (GRBs) and their afterglows are the most brilliant transient events in the Universe. Both the bursts themselves and their afterglows have been predicted to be visible out to redshifts of z approximately 20, and therefore to be powerful probes of the early Universe. The burst GRB 000131, at z = 4.50, was hitherto the most distant such event identified. Here we report the discovery of the bright near-infrared afterglow of GRB 050904 (ref. 4). From our measurements of the near-infrared afterglow, and our failure to detect the optical afterglow, we determine the photometric redshift of the burst to be z = 6.39 - 0.12 + 0.11 (refs 5-7). Subsequently, it was measured spectroscopically to be z = 6.29 +/- 0.01, in agreement with our photometric estimate. These results demonstrate that GRBs can be used to trace the star formation, metallicity, and reionization histories of the early Universe. PMID:16525465

  13. 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.

    2016-03-01

    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.

  14. The Onset of Gamma-Ray Burst Afterglow

    NASA Astrophysics Data System (ADS)

    Kobayashi, Shiho; Zhang, Bing

    2007-02-01

    We discuss the reference time t0 of afterglow light curves in the context of the standard internal-external shock model. The decay index of early afterglow is very sensitive to the reference time one chooses. In order to understand the nature of early afterglow, it is essential to take a correct reference time. Our simple analytic model provides a framework for understanding special relativistic effects involved in early afterglow phase. We evaluate light curves of reverse shock emission as well as those of forward shock emission, based on full hydrodynamic calculations. We show that the reference time does not shift significantly even in the thick-shell case. For external shock emission components, measuring times from the beginning of the prompt emission is a good approximation and it does not cause an early steep decay. In the thin-shell case, the energy transfer time from fireball ejecta to ambient medium typically extends to thousands of seconds. This might be related to the shallow decay phases observed in early X-ray afterglow at least for some bursts.

  15. Estimates for Lorentz Factors of Gamma-Ray Bursts from Early Optical Afterglow Observations

    NASA Astrophysics Data System (ADS)

    Hascoët, Romain; Beloborodov, Andrei M.; Daigne, Frédéric; Mochkovitch, Robert

    2014-02-01

    The peak time of optical afterglow may be used as a proxy to constrain the Lorentz factor Γ of the gamma-ray burst (GRB) ejecta. We revisit this method by including bursts with optical observations that started when the afterglow flux was already decaying; these bursts can provide useful lower limits on Γ. Combining all analyzed bursts in our sample, we find that the previously reported correlation between Γ and the burst luminosity L γ does not hold. However, the data clearly show a lower bound Γmin that increases with L γ. We suggest an explanation for this feature: explosions with large jet luminosities and Γ < Γmin suffer strong adiabatic cooling before their radiation is released at the photosphere; they produce weak bursts, barely detectable with present instruments. To test this explanation, we examine the effect of adiabatic cooling on the GRB location in the L γ - Γ plane using a Monte Carlo simulation of the GRB population. Our results predict detectable on-axis "orphan" afterglows. We also derive upper limits on the density of the ambient medium that decelerates the explosion ejecta. We find that the density in many cases is smaller than expected for stellar winds from normal Wolf-Rayet progenitors. The burst progenitors may be peculiar massive stars with weaker winds, or there might exist a mechanism that reduces the stellar wind a few years before the explosion.

  16. Estimates for Lorentz factors of gamma-ray bursts from early optical afterglow observations

    SciTech Connect

    Hascoët, Romain; Beloborodov, Andrei M.; Daigne, Frédéric; Mochkovitch, Robert

    2014-02-10

    The peak time of optical afterglow may be used as a proxy to constrain the Lorentz factor Γ of the gamma-ray burst (GRB) ejecta. We revisit this method by including bursts with optical observations that started when the afterglow flux was already decaying; these bursts can provide useful lower limits on Γ. Combining all analyzed bursts in our sample, we find that the previously reported correlation between Γ and the burst luminosity L {sub γ} does not hold. However, the data clearly show a lower bound Γ{sub min} that increases with L {sub γ}. We suggest an explanation for this feature: explosions with large jet luminosities and Γ < Γ{sub min} suffer strong adiabatic cooling before their radiation is released at the photosphere; they produce weak bursts, barely detectable with present instruments. To test this explanation, we examine the effect of adiabatic cooling on the GRB location in the L {sub γ} – Γ plane using a Monte Carlo simulation of the GRB population. Our results predict detectable on-axis 'orphan' afterglows. We also derive upper limits on the density of the ambient medium that decelerates the explosion ejecta. We find that the density in many cases is smaller than expected for stellar winds from normal Wolf-Rayet progenitors. The burst progenitors may be peculiar massive stars with weaker winds, or there might exist a mechanism that reduces the stellar wind a few years before the explosion.

  17. Optical flashes from internal pairs formed in gamma-ray burst afterglows

    DOE PAGESBeta

    Panaitescu, A.

    2015-06-09

    We develop a numerical formalism for calculating the distribution with energy of the (internal) pairs formed in a relativistic source from unscattered MeV–TeV photons. For gamma-ray burst (GRB) afterglows, this formalism is more suitable if the relativistic reverse shock that energizes the ejecta is the source of the GeV photons. The number of pairs formed is set by the source GeV output (calculated from the Fermi-LAT fluence), the unknown source Lorentz factor, and the unmeasured peak energy of the LAT spectral component. We show synchrotron and inverse-Compton light curves expected from pairs formed in the shocked medium and identify some criteria for testing a pair origin of GRB optical counterparts. Pairs formed in bright LAT afterglows with a Lorentz factor in the few hundreds may produce bright optical counterparts (more » $$R\\lt 10$$) lasting for up to one hundred seconds. As a result, the number of internal pairs formed from unscattered seed photons decreases very strongly with the source Lorentz factor, thus bright GRB optical counterparts cannot arise from internal pairs if the afterglow Lorentz factor is above several hundreds.« less

  18. Robust photometric redshift determinations of gamma-ray burst afterglows at z ≳ 2

    NASA Astrophysics Data System (ADS)

    Curran, P. A.; Wijers, R. A. M. J.; Heemskerk, M. H. M.; Starling, R. L. C.; Wiersema, K.; van der Horst, A. J.

    2008-11-01

    Context: Theory suggests that about 10% of Swift-detected gamma-ray bursts (GRBs) will originate at redshifts, z, greater than 5 yet a number of high redshift candidates may be left unconfirmed due to the lack of measured redshifts. Aims: Here we introduce our code, GRBz, a method of simultaneous multi-parameter fitting of GRB afterglow optical and near infrared, spectral energy distributions. It allows for early determinations of the photometric redshift, spectral index and host extinction to be made. Methods: We assume that GRB afterglow spectra are well represented by a power-law decay and model the effects of absorption due to the Lyman forest and host extinction. We use a genetic algorithm-based routine to simultaneously fit the parameters of interest, and a Monte Carlo error analysis. Results: We use GRBs of previously determined spectroscopic redshifts to prove our method, while also introducing new near infrared data of GRB 990510 which further constrains the value of the host extinction. Conclusions: Our method is effective in estimating the photometric redshift of GRBs, relatively unbiased by assumptions of the afterglow spectral index or the host galaxy extinction. Monte Carlo error analysis is required as the method of error estimate based on the optimum population of the genetic algorithm underestimates errors significantly.

  19. Optical flashes from internal pairs formed in gamma-ray burst afterglows

    SciTech Connect

    Panaitescu, A.

    2015-06-09

    We develop a numerical formalism for calculating the distribution with energy of the (internal) pairs formed in a relativistic source from unscattered MeV–TeV photons. For gamma-ray burst (GRB) afterglows, this formalism is more suitable if the relativistic reverse shock that energizes the ejecta is the source of the GeV photons. The number of pairs formed is set by the source GeV output (calculated from the Fermi-LAT fluence), the unknown source Lorentz factor, and the unmeasured peak energy of the LAT spectral component. We show synchrotron and inverse-Compton light curves expected from pairs formed in the shocked medium and identify some criteria for testing a pair origin of GRB optical counterparts. Pairs formed in bright LAT afterglows with a Lorentz factor in the few hundreds may produce bright optical counterparts ($R\\lt 10$) lasting for up to one hundred seconds. As a result, the number of internal pairs formed from unscattered seed photons decreases very strongly with the source Lorentz factor, thus bright GRB optical counterparts cannot arise from internal pairs if the afterglow Lorentz factor is above several hundreds.

  20. 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

  1. VizieR Online Data Catalog: Position catalogue of Swift XRT afterglows (Moretti+, 2006)

    NASA Astrophysics Data System (ADS)

    Moretti, A.; Perri, M.; Capalbi, M.; Angelini, L.; Hill, J. E.; Campana, S.; Burrows, D. N.; Osborne, J. P.; Tagliaferri, G.; Cusumano, G.; Giommi, P.; Romano, P.; Mineo, T.; Kennea, J.; Morris, D.; Nousek, J.; Pagani, C.; Racusin, J.; Abbey, A. F.; Beardmore, A. P.; Godet, O.; Goad, M. R.; Page, K. L.; Wells, A. A.; Chincarini, G.

    2006-02-01

    We present a catalogue of refined positions of 68 gamma ray burst (GRB) afterglows observed by the Swift X-ray Telescope (XRT) from the launch up to 2005 Oct. 16. This is a result of the refinement of the XRT boresight calibration. We tested this correction by means of a systematic study of a large sample of X-ray sources observed by XRT with well established optical counterparts. We found that we can reduce the systematic error radius of the measurements by a factor of two, from 6.5 to 3.2 (90% of confidence). We corrected all the positions of the afterglows observed by XRT in the first 11 months of the Swift mission. This is particularly important for the 37 X-ray afterglows without optical counterpart. Optical follow-up of dark GRBs, in fact, will be more efficient with the use of the more accurate XRT positions. (1 data file).

  2. The Flat Decay Phase in the Early X-Ray Afterglows of Swift GRBs

    SciTech Connect

    Granot, Jonathan; /KIPAC, Menlo Park

    2007-03-27

    Many Swift GRBs show an early phase of shallow decay in their X-ray afterglows, lasting from t {approx} 10{sup 2.5} s to {approx} 10{sup 4} s after the GRB, where the flux decays as {approx} t{sup -0.2} - t{sup -0.8}. This is perhaps the most mysterious of the new features discovered by Swift in the early X-ray afterglow, since it is still not clear what causes it. I discuss different possible explanations for this surprising new discovery, as well as their potential implications for the gamma-ray efficiency, the afterglow kinetic energy, and perhaps even for the physics of collisionless relativistic shocks.

  3. Machine Learning Search for Gamma-Ray Burst Afterglows in Optical Images

    NASA Astrophysics Data System (ADS)

    Topinka, M.

    2016-06-01

    Thanks to the advances in robotic telescopes, time domain astronomy leads to a large number of transient events detected in images every night. Data mining and machine learning tools used for object classification are presented. The goal is to automatically classify transient events for both further follow-up by a larger telescope and for statistical studies of transient events. Special attention is given to the identification of gamma-ray burst afterglows. Machine learning techniques are used to identify GROND gamma-ray burst afterglow among the astrophysical objects present in the SDSS archival images based on the g'-r', r'-i' and i'-z' color indices. The performance of the support vector machine, random forest and neural network algorithms is compared. A joint meta-classifier, built on top of the individual classifiers, can identify GRB afterglows with the overall accuracy of ≳ 90%.

  4. Modeling the Afterglows of Gamma Ray Bursts for Arbitrary Viewing Angles

    NASA Astrophysics Data System (ADS)

    Ryan, Dominic; Morsony, B. J.

    2014-01-01

    We present models of GRB afterglow light curves for simulated GRBs. We describe a method by which the energy distribution of the system can be determined for an arbitrary viewing angle relative to the jet axis. From this distribution, we calculate the time-evolution of the expanding shockwave from the stellar explosion. With relativistic considerations, we can model the synchrotron radiation emitted in this shockwave and construct the time-evolution of the afterglows seen by an observer at an arbitrary angle. We will present results of the calculated afterglow spectra as functions of time for energy distributions from numerical simulations as well as for simple jet models. This work was partially supported by the National Science Foundation's REU program through NSF Award AST-1004881 to the University of Wisconsin-Madison.

  5. Study of argon–oxygen flowing afterglow

    NASA Astrophysics Data System (ADS)

    Mazánková, V.; Trunec, D.; Navrátil, Z.; Raud, J.; Krčma, F.

    2016-06-01

    The reaction kinetics in argon–oxygen flowing afterglow (post-discharge) was studied using NO titration and optical emission spectroscopy. The flowing DC post-discharge in argon–oxygen mixture was created in a quartz tube at the total gas pressure of 1000 Pa and discharge power of 90 W. The O(3P) atom concentration was determined by NO titration at different places along the flow tube. The optical emission spectra were also measured along the flow tube. Argon spectral lines, oxygen lines at 777 nm and 844.6 nm and atmospheric A-band of {{\\text{O}}2} were identified in the spectra. Rotational temperature of {{\\text{O}}2} was determined from the oxygen atmospheric A-band and also the outer wall temperature of the flow tube was measured by a thermocouple and by an IR thermometer. A zero-dimensional kinetic model for the reactions in the afterglow was developed. This model allows the time dependencies of particle concentrations and of gas temperature to be calculated. The wall recombination probability for O(3P) atoms {γ\\text{O≤ft(\\text{P}\\right)}}=≤ft(1.63+/- 0.06\\right)× {{10}-3} and wall deactivation probability for {{\\text{O}}2} (b {{}1}Σ\\text{g}+ ) molecules {γ{{\\text{O}2}≤ft(\\text{b}\\right)}}=≤ft(1.7+/- 0.1\\right)× {{10}-3} were determined from the fit of model results to experimental data. Sensitivity analysis was applied for the analysis of kinetic model in order to reveal the most important reactions in the model. The calculated gas temperature increases in the afterglow and then decreases at later afterglow times after reaching the maximum. This behavior is in good agreement with the spatial rotational temperature dependence. A similar trend was also observed at outer wall temperature measurement.

  6. A GRB tool shed

    NASA Astrophysics Data System (ADS)

    Haglin, David J.; Roiger, Richard J.; Hakkila, Jon; Pendleton, Geoffrey; Mallozzi, Robert

    2000-09-01

    We describe the design of a suite of software tools to allow users to query Gamma Ray Burst (GRB) data and perform data mining expeditions. We call this suite of tools a shed (SHell for Expeditions using Datamining). Our schedule is to have a completed prototype (funded via the NASA AISRP) by February, 2002. Meanwhile, interested users will find a partially functioning tool shed at http:/grb.mankato.msus.edu. .

  7. GRB Catalog: Bursts from Vela to Swift

    NASA Technical Reports Server (NTRS)

    Angelini, L.

    2008-01-01

    Gamma ray burst (GRB) astronomy started when the first event was recorded on July 2, 1967 by Vela 4a and 4b. Since then many missions have flown experiments capable of detecting GRBs. The events collected by these older experiments are mostly available in paper copy, each containing a few ten to a few hundred bursts. No systematic effort in cataloging of these bursts has been available. In some cases the information is unpublished and in others difficult to retrieve. The first major GRB catalog was obtained by GRO with the BATSE experiment. It contains more than 2000 bursts and includes homogeneous information for each of the bursts. With the launch of Swift, the first Gamma-ray/X-ray mission dedicated to the study of GRBs and their afterglows, a wealth of information is collected by the Swift instrument as well as from ground-based telescopes. This talk will describe the efforts to create a comprehensive GRBCAT and its current status and future prospective.

  8. Host Galaxy of the Dark Gamma-Ray Burst GRB 051008

    NASA Astrophysics Data System (ADS)

    Volnova, A. A.; Pozanenko, A. S.; Rumyantsev, V. V.; Biryukov, V. V.; Ibrahimov, M. A.; Sharapov, D. A.; Kann, D. A.; Gorosabel, J.; Castro-Tirado, A. J.; de Ugarte Postigo, A.

    2011-08-01

    We present observations of the dark Gamma-Ray Burst GRB 051008, the burst detected only in gamma- and X-rays but without any optical and radio afterglows. We identified the host galaxy of the burst, it has the R-magnitude of 23m.92+/-0m.07. The photometrical redshift of the galaxy is z = 1.07+/-0.13. We provide arguments in favor of the hypothesis that the galaxy is situated in a cluster. This is one of a few cases of the dark GRB host detection. We present details of observations, intrinsic properties of the host ant its environment.

  9. LATE-TIME OBSERVATIONS OF GRB 080319B: JET BREAK, HOST GALAXY, AND ACCOMPANYING SUPERNOVA

    SciTech Connect

    Tanvir, N. R.; O'Brien, P. T.; Wiersema, K.; Starling, R. L. C.; Rol, E.; Levan, A. J.; Svensson, K.; Fruchter, A. S.; Granot, J.; Jakobsson, P.; Fynbo, J.; Hjorth, J.; Curran, P. A.; Burrows, D. N.; Genet, F.

    2010-12-10

    The Swift-discovered GRB 080319B was by far the most distant source ever observed at naked-eye brightness, reaching a peak apparent magnitude of 5.3 at a redshift of z = 0.937. We present our late-time optical (Hubble Space Telescope, Gemini, and Very Large Telescope) and X-ray (Chandra) observations, which confirm that an achromatic break occurred in the power-law afterglow light curve at {approx}11 days post-burst. This most likely indicates that the gamma-ray burst (GRB) outflow was collimated, which for a uniform jet would imply a total energy in the jet E{sub jet} {approx}> 10{sup 52} erg. Our observations also show a late-time excess of red light, which is well explained if the GRB was accompanied by a supernova (SN), similar to those seen in some other long-duration GRBs. The latest observations are dominated by light from the host and show that the GRB took place in a faint dwarf galaxy (r(AB) {approx} 27.0, rest frame M{sub B} {approx} -17.2). This galaxy is small even by the standards of other GRB hosts, which is suggestive of a low-metallicity environment. Intriguingly, the properties of this extreme event-a small host and bright SN-are entirely typical of the very low luminosity bursts such as GRB 980425 and GRB 060218.

  10. Late-time Observations of GRB 080319B: Jet Break, Host Galaxy, and Accompanying Supernova

    NASA Astrophysics Data System (ADS)

    Tanvir, N. R.; Rol, E.; Levan, A. J.; Svensson, K.; Fruchter, A. S.; Granot, J.; O'Brien, P. T.; Wiersema, K.; Starling, R. L. C.; Jakobsson, P.; Fynbo, J.; Hjorth, J.; Curran, P. A.; van der Horst, A. J.; Kouveliotou, C.; Racusin, J. L.; Burrows, D. N.; Genet, F.

    2010-12-01

    The Swift-discovered GRB 080319B was by far the most distant source ever observed at naked-eye brightness, reaching a peak apparent magnitude of 5.3 at a redshift of z = 0.937. We present our late-time optical (Hubble Space Telescope, Gemini, and Very Large Telescope) and X-ray (Chandra) observations, which confirm that an achromatic break occurred in the power-law afterglow light curve at ~11 days post-burst. This most likely indicates that the gamma-ray burst (GRB) outflow was collimated, which for a uniform jet would imply a total energy in the jet E jet >~ 1052 erg. Our observations also show a late-time excess of red light, which is well explained if the GRB was accompanied by a supernova (SN), similar to those seen in some other long-duration GRBs. The latest observations are dominated by light from the host and show that the GRB took place in a faint dwarf galaxy (r(AB) ≈ 27.0, rest frame MB ≈ -17.2). This galaxy is small even by the standards of other GRB hosts, which is suggestive of a low-metallicity environment. Intriguingly, the properties of this extreme event—a small host and bright SN—are entirely typical of the very low luminosity bursts such as GRB 980425 and GRB 060218.

  11. GRB hosts through cosmic time. VLT/X-Shooter emission-line spectroscopy of 96 γ-ray-burst-selected galaxies at 0.1

    NASA Astrophysics Data System (ADS)

    Krühler, T.; Malesani, D.; Fynbo, J. P. U.; Hartoog, O. E.; Hjorth, J.; Jakobsson, P.; Perley, D. A.; Rossi, A.; Schady, P.; Schulze, S.; Tanvir, N. R.; Vergani, S. D.; Wiersema, K.; Afonso, P. M. J.; Bolmer, J.; Cano, Z.; Covino, S.; D'Elia, V.; de Ugarte Postigo, A.; Filgas, R.; Friis, M.; Graham, J. F.; Greiner, J.; Goldoni, P.; Gomboc, A.; Hammer, F.; Japelj, J.; Kann, D. A.; Kaper, L.; Klose, S.; Levan, A. J.; Leloudas, G.; Milvang-Jensen, B.; Nicuesa Guelbenzu, A.; Palazzi, E.; Pian, E.; Piranomonte, S.; Sánchez-Ramírez, R.; Savaglio, S.; Selsing, J.; Tagliaferri, G.; Vreeswijk, P. M.; Watson, D. J.; Xu, D.

    2015-09-01

    We present data and initial results from VLT/X-Shooter emission-line spectroscopy of 96 galaxies selected by long γ-ray bursts (GRBs) at 0.1 GRB host spectra available to date. Most of our GRBs were detected by Swift and 76% are at 0.5 emission-line widths (σ). We study GRB hosts up to z ~ 3.5 and find a strong change in their typical physical properties with redshift. The median SFR of our GRB hosts increases from SFRmed ~ 0.6 M⊙ yr-1 at z ~ 0.6 up to SFRmed ~ 15 M⊙ yr-1 at z ~ 2. A higher ratio of [O iii]/[O ii] at higher redshifts leads to an increasing distance of GRB-selected galaxies to the locus of local galaxies in the Baldwin-Phillips-Terlevich diagram. There is weak evidence for a redshift evolution in AV and σ, with the highest values seen at z ~ 1.5 (AV) or z ~ 2 (σ). Oxygen abundances of the galaxies are distributed between 12 + log (O/H) = 7.9 and 12 + log (O/H) = 9.0 with a median 12 + log (O/H)med ~ 8.5. The fraction of GRB-selected galaxies with super-solar metallicities is ~20% at z< 1 in the adopted metallicity scale. This is significantly less than the fraction of total star formation in similar galaxies, illustrating that GRBs are scarce in high metallicity environments. At z ~ 3, sensitivity limits us to probing only the most luminous GRB hosts for which we derive metallicities of Z ≲ 0.5 Z⊙. Together with a high incidence of Z ~ 0.5 Z⊙ galaxies at z ~ 1.5, this indicates that a metallicity dependence at low redshift will not be dominant at z ~ 3. Significant correlations exist between the hosts' physical properties. Oxygen abundance, for example, relates to AV (12 + log (O/H) ∝ 0.17·AV), line width (12 + log (O/H) ∝ σ0.6), and SFR (12 + log (O/H) ∝ SFR0.2). In the

  12. Constraining properties of GRB magnetar central engines using the observed plateau luminosity and duration correlation

    NASA Astrophysics Data System (ADS)

    Rowlinson, A.; Gompertz, B. P.; Dainotti, M.; O'Brien, P. T.; Wijers, R. A. M. J.; van der Horst, A. J.

    2014-09-01

    An intrinsic correlation has been identified between the luminosity and duration of plateaus in the X-ray afterglows of gamma-ray bursts (GRBs; Dainotti et al. 2008), suggesting a central engine origin. The magnetar central engine model predicts an observable plateau phase, with plateau durations and luminosities being determined by the magnetic fields and spin periods of the newly formed magnetar. This paper analytically shows that the magnetar central engine model can explain, within the 1σ uncertainties, the correlation between plateau luminosity and duration. The observed scatter in the correlation most likely originates in the spread of initial spin periods of the newly formed magnetar and provides an estimate of the maximum spin period of ˜35 ms (assuming a constant mass, efficiency and beaming across the GRB sample). Additionally, by combining the observed data and simulations, we show that the magnetar emission is most likely narrowly beamed and has ≲20 per cent efficiency in conversion of rotational energy from the magnetar into the observed plateau luminosity. The beaming angles and efficiencies obtained by this method are fully consistent with both predicted and observed values. We find that short GRBs and short GRBs with extended emission lie on the same correlation but are statistically inconsistent with being drawn from the same distribution as long GRBs, this is consistent with them having a wider beaming angle than long GRBs.

  13. On binary driven hypernovae and their nested late X-ray emission

    NASA Astrophysics Data System (ADS)

    Muccino, Marco; Ruffini, Remo; Bianco, Carlo Luciano; Enderli, Maxime; Kovacevic, Milos; Izzo, Luca; Penacchioni, Ana Virginia; Pisani, Giovanni Battista; Rueda, Jorge A.; Wang, Yu

    2015-07-01

    The induced gravitational collapse (IGC) paradigm addresses energetic (1052-1054 erg), long gamma-ray bursts (GRBs) associated to supernovae (SNe) and proposes as their progenitors tight binary systems composed of an evolved FeCO core and a companion neutron star (NS). Their emission is characterized by four specific episodes: Episode 1, corresponding to the on-set of the FeCO SN explosion and the accretion of the ejecta onto the companion NS; Episode 2, related the collapse of the companionNS to a black hole (BH) and to the emission of a long GRB; Episode 3, observed in X-rays and characterized by a steep decay, a plateau phase and a late power-law decay; Episode 4, corresponding to the optical SN emission due to the 56Ni decay. We focus on Episode 3 and we show that, from the thermal component observed during the steep decay of the prototype GRB 090618, the emission region has a typical dimension of ~1013 cm, which is inconsistent with the typical size of the emitting region of GRBs, e.g., ~1016 cm. We propose, therefore, that the X-ray afterglow emission originates from a spherically symmetric SN ejecta expanding at G ˜ 2 or, possibly, from the accretion onto the newly formed black hole, and we name these systems "binary driven hypernovae" (BdHNe). This interpretation is alternative to the traditional afterglow model based on the GRB synchrotron emission from a collimated jet outflow, expanding at ultra-relativistic Lorentz factor of G ~ 102-103 and originating from the collapse of a single object. We show then that the rest-frame energy band 0.3-10 keV X-ray luminosities of three selected BdHNe, GRB 060729, GRB 061121, and GRB 130427A, evidence a precisely constrained "nested" structure and satisfy precise scaling laws between the average prompt luminosity, < Liso>, and the luminosity at the end of the plateau, La, as functions of the time at the end of the plateau. All these features extend the applicability of the "cosmic candle" nature of Episode 3. The

  14. Discovery of the nearby long, soft GRB 100316D with an associated supernova

    NASA Astrophysics Data System (ADS)

    Starling, R. L. C.; Wiersema, K.; Levan, A. J.; Sakamoto, T.; Bersier, D.; Goldoni, P.; Oates, S. R.; Rowlinson, A.; Campana, S.; Sollerman, J.; Tanvir, N. R.; Malesani, D.; Fynbo, J. P. U.; Covino, S.; D'Avanzo, P.; O'Brien, P. T.; Page, K. L.; Osborne, J. P.; Vergani, S. D.; Barthelmy, S.; Burrows, D. N.; Cano, Z.; Curran, P. A.; de Pasquale, M.; D'Elia, V.; Evans, P. A.; Flores, H.; Fruchter, A. S.; Garnavich, P.; Gehrels, N.; Gorosabel, J.; Hjorth, J.; Holland, S. T.; van der Horst, A. J.; Hurkett, C. P.; Jakobsson, P.; Kamble, A. P.; Kouveliotou, C.; Kuin, N. P. M.; Kaper, L.; Mazzali, P. A.; Nugent, P. E.; Pian, E.; Stamatikos, M.; Thöne, C. C.; Woosley, S. E.

    2011-03-01

    We report the Swift discovery of the nearby long, soft gamma-ray burst GRB 100316D, and the subsequent unveiling of its low-redshift host galaxy and associated supernova. We derive the redshift of the event to be z= 0.0591 ± 0.0001 and provide accurate astrometry for the gamma-ray burst (GRB) supernova (SN). We study the extremely unusual prompt emission with time-resolved γ-ray to X-ray spectroscopy and find that the spectrum is best modelled with a thermal component in addition to a synchrotron emission component with a low peak energy. The X-ray light curve has a remarkably shallow decay out to at least 800 s. The host is a bright, blue galaxy with a highly disturbed morphology and we use Gemini-South, Very Large Telescope and Hubble Space Telescope observations to measure some of the basic host galaxy properties. We compare and contrast the X-ray emission and host galaxy of GRB 100316D to a subsample of GRB-SNe. GRB 100316D is unlike the majority of GRB-SNe in its X-ray evolution, but resembles rather GRB 060218, and we find that these two events have remarkably similar high energy prompt emission properties. Comparison of the host galaxies of GRB-SNe demonstrates, however, that there is a great diversity in the environments in which GRB-SNe can be found. GRB 100316D is an important addition to the currently sparse sample of spectroscopically confirmed GRB-SNe, from which a better understanding of long GRB progenitors and the GRB-SN connection can be gleaned.

  15. VizieR Online Data Catalog: GRB 130606A VLT/X-shooter spectroscopy (Hartoog+, 2015)

    NASA Astrophysics Data System (ADS)

    Hartoog, O. E.; Malesani, D.; Fynbo, J. P. U.; Goto, T.; Kruhler, T.; Vreeswijk, P. M.; De Cia, A.; Xu, D.; Moller, P.; Covino, S.; D'Elia, V.; Flores, H.; Goldoni, P.; Hjorth, J.; Jakobsson, P.; Krogager, J.-K.; Kaper, L.; Ledoux, C.; Levan, A. J.; Milvang-Jensen, B.; Sollerman, J.; Sparre, M.; Tagliaferri, G.; Tanvir, N. R.; de Ugarte Postigo, A.; Vergani, S. D.; Wiersema, K.; Datson, J.; Salinas, R.; Mikkelsen, K.; Aghanim, N.

    2015-06-01

    Reduced visual (VIS) and Near-IR (NIR) VLT/X-shooter spectra (before normalization) of the afterglow of GRB130606A (Pipeline produced, see headers of the fits files for additional info). The original data files and calibrations can be found on http://archive.eso.org/wdb/wdb/eso/xshooter/form under program 091.C-0934(C) querying the following coordinates: coord1 = 16 37 35.188 coord2 = +29 47 47.03 (2 data files).

  16. GRB 131014A: A Laboratory for Studying the Thermal-like and Non-thermal Emissions in Gamma-Ray Bursts, and the New LnThi-EnTh,restpeak,i Relation

    NASA Astrophysics Data System (ADS)

    Guiriec, S.; Mochkovitch, R.; Piran, T.; Daigne, F.; Kouveliotou, C.; Racusin, J.; Gehrels, N.; McEnery, J.

    2015-11-01

    Over the past few years, evidence has been accumulated in support of the existence of a thermal-like component during the prompt phase of gamma-ray bursts (GRBs). However, this component, which is often associated with the GRB jet's photosphere, is usually subdominant compared to a much stronger non-thermal one. The prompt emission of GRB 131014A—detected by the Fermi Gamma-ray Space Telescope (hereafter Fermi)—provides a unique opportunity to trace the history of this thermal-like component. Indeed, the thermal emission in GRB 131014A is much more intense than in other GRBs and a pure thermal episode is observed during the initial 0.16 s. The thermal-like component cools monotonically during the first second while the non-thermal emission kicks off. The intensity of the non-thermal component progressively increases until being energetically dominant at late time, similar to what is typically observed. This is a perfect scenario to disentangle the thermal component from the non-thermal component. The initial decaying and cooling phase of the thermal-like component is followed by a strong re-brightening and a re-heating episode; however, despite a much brighter second emission phase, the temperature of the thermal component does not reach its initial value. This re-brightening episode is followed by a global constant cooling until the end of the burst. We note that there is a shallower low-energy spectral slope than the typical index value +1, corresponding to a pure Planck function, which better matches with the thermal-like spectral shape; a spectral index around +0.6 seems to be in better agreement with the data. The non-thermal component is adequately fitted with a Band function whose low- and high-energy power-law indices are ˜-0.7 and <˜-3, respectively; this is also statistically globally equivalent to a cutoff power law with a ˜-0.7 index. This is in agreement with our previous results. Finally, a strong correlation is observed between the time

  17. GRB 090313 AND THE ORIGIN OF OPTICAL PEAKS IN GAMMA-RAY BURST LIGHT CURVES: IMPLICATIONS FOR LORENTZ FACTORS AND RADIO FLARES

    SciTech Connect

    Melandri, A.; Kobayashi, S.; Mundell, C. G.; Guidorzi, C.; Bersier, D.; Steele, I. A.; Smith, R. J.; De Ugarte Postigo, A.; Pooley, G.; Yoshida, M.; Castro-Tirado, A. J.; Gorosabel, J.; Kubanek, P.; Sota, A.; Gomboc, A.; Bremer, M.; Winters, J. M.; De Gregorio-Monsalvo, I.; GarcIa-Appadoo, D.

    2010-11-10

    We use a sample of 19 gamma-ray bursts (GRBs) that exhibit single-peaked optical light curves to test the standard fireball model by investigating the relationship between the time of the onset of the afterglow and the temporal rising index. Our sample includes GRBs and X-ray flashes for which we derive a wide range of initial Lorentz factors (40 < {Gamma} < 450). Using plausible model parameters, the typical frequency of the forward shock is expected to lie close to the optical band; within this low typical frequency framework, we use the optical data to constrain {epsilon}{sub e} and show that values derived from the early time light-curve properties are consistent with published typical values derived from other afterglow studies. We produce expected radio light curves by predicting the temporal evolution of the expected radio emission from forward and reverse shock components, including synchrotron self-absorption effects at early time. Although a number of GRBs in this sample do not have published radio measurements, we demonstrate the effectiveness of this method in the case of Swift GRB 090313, for which millimetric and centimetric observations were available, and conclude that future detections of reverse-shock radio flares with new radio facilities such as the EVLA and ALMA will test the low-frequency model and provide constraints on magnetic models.

  18. How Can The SN-GRB Time Delay Be Measured?

    NASA Technical Reports Server (NTRS)

    Norris, J. P.; Bonnell, J. T.

    2003-01-01

    The connection between SNe and GRBs, launched by SN 1998bw / GRB 980425 and clinched by SN 2003dh / GRB 030329-with the two GRBs differing by a factor of approximately 50000 in luminosity-so far suggests a rough upper limit of approximately 1-2 days for the delay between SN and GRB. Only four SNe have had nonnegligible coverage in close coincidence with the initial explosion, near the W shock breakout: two Qpe II, and two Type IC, SN 1999ex and SN 1998bw. For the latter, only a hint of the minimum between the UV maximum and the radioactivity bump served to help constrain the interval between SN and GRB. Swift GRB alerts may provide the opportunity to study many SNe through the UV breakout phase: GRB 980425 look dikes -apparently nearby, low- luminosity, soft-spectrum, long-lag GRBs-accounted for half of BATSE bursts near threshold, and may dominate the Swift yield near threshold, since it has sensitivity to lower energies than did BATSE. The SN to GRB delay timescale should be better constrained by prompt UV/optical observations alerted by these bursts. Definitive delay measurements may be obtained if long-lag bursters are truly nearby: The SNe/GRBs could emit gravitational radiation detectable by LIGO-II if robust non-axisymmetric bar instabilities develop during core collapse, and/or neutrino emission may be detectable as suggested by Meszaros et al.

  19. 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.

  20. DETERMINATION OF THE INTRINSIC LUMINOSITY TIME CORRELATION IN THE X-RAY AFTERGLOWS OF GAMMA-RAY BURSTS

    SciTech Connect

    Dainotti, Maria Giovanna; Petrosian, Vahe'; Singal, Jack; Ostrowski, Michal E-mail: vahep@stanford.edu E-mail: dainotti@oa.uj.edu.pl

    2013-09-10

    Gamma-ray bursts (GRBs), which have been observed up to redshifts z Almost-Equal-To 9.5, can be good probes of the early universe and have the potential to test cosmological models. Dainotti's analysis of GRB Swift afterglow light curves with known redshifts and a definite X-ray plateau shows an anti-correlation between the rest-frame time when the plateau ends (the plateau end time) and the calculated luminosity at that time (or approximately an anti-correlation between plateau duration and luminosity). Here, we present an update of this correlation with a larger data sample of 101 GRBs with good light curves. Since some of this correlation could result from the redshift dependences of these intrinsic parameters, namely, their cosmological evolution, we use the Efron-Petrosian method to reveal the intrinsic nature of this correlation. We find that a substantial part of the correlation is intrinsic and describe how we recover it and how this can be used to constrain physical models of the plateau emission, the origin of which is still unknown. The present result could help to clarify the debated nature of the plateau emission.

  1. 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.

  2. A Characteristic Value for the BAT/XRT- plateau Flux Ratio in GRB?

    NASA Astrophysics Data System (ADS)

    Kazanas, Demosthenes; Racusin, Judith; Sultana, Joseph; Mastichiadis, Apostolos

    2015-04-01

    We present the statistics of the ratio, R, between the prompt and afterglow ``plateau'' fluxes of GRB. This we define as the ratio between the mean prompt energy flux in Swift BAT and the Swift XRT one, immediately following the steep transition between these two states and the beginning of the afterglow stage referred to as the ``plateau.'' Like the distribution of many other GRB observables, the histogram of R is log-normal with maximum at a value Rm ~= 2 , 000 , FWHM of about 2 decades and with the entire distribution spanning about 5 decades in the value of R. We note that the peak of the distribution is close to the proton-to-electron mass ratio (Rm ~=mp /me = 1836) , as proposed to be the case in an earlier publication, on the basis of a specific model of the GRB dissipation process. It therefore appears that, in addition to the values of the energy of peak luminosity Ep ~mec2 , GRB present us with one more quantity with an apparent characteristic value. The fact that the values of both these quantities (Ep and R) are consistent with the same specific model invoked to account for the efficient conversion of their relativistic proton energies to electrons, argues favorably for its underlying assumptions.

  3. Revealing the Jet Structure of Grb 030329 With High Resolution Multicolor Photometry

    SciTech Connect

    Gorosabel, Javier; Castro-Tirado, A.J.; Ramirez-Ruiz, E.; Granot, J.; Caon, N.; Cairos, L.M.; Rubio-Herrera, E.; Guziy, S.; de Ugarte Postigo, A.; Jelinek, M.; /IAA, Granada /Princeton, Inst. Advanced Study /KIPAC, Menlo Park /Laguna U., Tenerife /Amsterdam U., Astron. Inst.

    2006-03-15

    We present multicolor optical observations of the nearby (z = 0.1685) GRB030329 obtained with the same instrumentation over a time period of 6 hours for a total of an unprecedented 475 quasi-simultaneous B V R observations. The achromatic steepening in the optical, which occurs at t {approx} 0.7 days, provides evidence for a dynamic transition of the source, and can be most readily explained by models in which the GRB ejecta are collimated into a jet. Since the current state-of-the-art modeling of GRB jets is still flawed with uncertainties, we use these data to critically assess some classes of models that have been proposed in the literature. The data, especially the smooth decline rate seen in the optical afterglow, are consistent with a model in which GRB030329 was a homogeneous, sharp-edged jet, viewed near its edge interacting with a uniform external medium, or viewed near its symmetry axis with a stratified wind-like external environment. The lack of short timescale fluctuations in the optical afterglow flux down to the 0.5 per cent level puts stringent constraints on possible small scale angular inhomogeneities within the jet or fluctuations in the external density.

  4. Discovery of a cosmological, relativistic outburst via its rapidly fading optical emission

    SciTech Connect

    Cenko, S. Bradley; Nugent, Peter E.; Miller, Adam A.; Bloom, Joshua S.; Filippenko, Alexei V.; Kulkarni, S. R.; Horesh, Assaf; Carpenter, John; Perley, Daniel A.; Groot, Paul J.; Hallinan, G.; Corsi, Alessandra; Fox, Derek B.; Frail, Dale A.; Gruber, D.; Rau, Arne; Gal-Yam, Avishay; Ofek, Eran O.; MacLeod, Chelsea L.; Kasliwal, Mansi M.; and others

    2013-06-01

    We report the discovery by the Palomar Transient Factory (PTF) of the transient source PTF11agg, which is distinguished by three primary characteristics: (1) bright (R {sub peak} = 18.3 mag), rapidly fading (ΔR = 4 mag in Δt = 2 days) optical transient emission; (2) a faint (R = 26.2 ± 0.2 mag), blue (g' – R = 0.17 ± 0.29 mag) quiescent optical counterpart; and (3) an associated year-long, scintillating radio transient. We argue that these observed properties are inconsistent with any known class of Galactic transients (flare stars, X-ray binaries, dwarf novae), and instead suggest a cosmological origin. The detection of incoherent radio emission at such distances implies a large emitting region, from which we infer the presence of relativistic ejecta. The observed properties are all consistent with the population of long-duration gamma-ray bursts (GRBs), marking the first time such an outburst has been discovered in the distant universe independent of a high-energy trigger. We searched for possible high-energy counterparts to PTF11agg, but found no evidence for associated prompt emission. We therefore consider three possible scenarios to account for a GRB-like afterglow without a high-energy counterpart: an 'untriggered' GRB (lack of satellite coverage), an 'orphan' afterglow (viewing-angle effects), and a 'dirty fireball' (suppressed high-energy emission). The observed optical and radio light curves appear inconsistent with even the most basic predictions for off-axis afterglow models. The simplest explanation, then, is that PTF11agg is a normal, on-axis long-duration GRB for which the associated high-energy emission was simply missed. However, we have calculated the likelihood of such a serendipitous discovery by PTF and find that it is quite small (≈2.6%). While not definitive, we nonetheless speculate that PTF11agg may represent a new, more common (>4 times the on-axis GRB rate at 90% confidence) class of relativistic outbursts lacking associated high

  5. Pair-dominated GeV-Optical Flash in GRB 130427A

    NASA Astrophysics Data System (ADS)

    Vurm, Indrek; Hascoët, Romain; Beloborodov, Andrei M.

    2014-07-01

    We show that the light curve of the double GeV+optical flash in GRB 130427A is consistent with radiation from the blast wave in a wind-type medium with density parameter A = ρr 2 ~ 5 × 1010 g cm-1. The peak of the flash is emitted by copious e ± pairs created and heated in the blast wave; our first-principle calculation determines the pair-loading factor and temperature of the shocked plasma. Using detailed radiative transfer simulations, we reconstruct the observed double flash. The optical flash is dominated by synchrotron emission from the thermal plasma behind the forward shock, and the GeV flash is produced via inverse Compton (IC) scattering by the same plasma. The seed photons for IC scattering are dominated by the prompt MeV radiation during the first tens of seconds, and by the optical to X-ray afterglow thereafter. IC cooling of the thermal plasma behind the forward shock reproduces all GeV data from a few seconds to ~1 day. We find that the blast wave Lorentz factor at the peak of the flash is Γ ≈ 200, and the forward shock magnetization is ɛB ~ 2 × 10-4. An additional source is required by the data in the optical and X-ray bands at times >102 s we speculate that this additional source may be a long-lived reverse shock in the explosion ejecta.

  6. GRB 090423 at a redshift of z approximately 8.1.

    PubMed

    Salvaterra, R; Valle, M Della; Campana, S; Chincarini, G; Covino, S; D'Avanzo, P; Fernández-Soto, A; Guidorzi, C; Mannucci, F; Margutti, R; Thöne, C C; Antonelli, L A; Barthelmy, S D; De Pasquale, M; D'Elia, V; Fiore, F; Fugazza, D; Hunt, L K; Maiorano, E; Marinoni, S; Marshall, F E; Molinari, E; Nousek, J; Pian, E; Racusin, J L; Stella, L; Amati, L; Andreuzzi, G; Cusumano, G; Fenimore, E E; Ferrero, P; Giommi, P; Guetta, D; Holland, S T; Hurley, K; Israel, G L; Mao, J; Markwardt, C B; Masetti, N; Pagani, C; Palazzi, E; Palmer, D M; Piranomonte, S; Tagliaferri, G; Testa, V

    2009-10-29

    Gamma-ray bursts (GRBs) are produced by rare types of massive stellar explosion. Their rapidly fading afterglows are often bright enough at optical wavelengths that they are detectable at cosmological distances. Hitherto, the highest known redshift for a GRB was z = 6.7 (ref. 1), for GRB 080913, and for a galaxy was z = 6.96 (ref. 2). Here we report observations of GRB 090423 and the near-infrared spectroscopic measurement of its redshift, z = 8.1(-0.3)(+0.1). This burst happened when the Universe was only about 4 per cent of its current age. Its properties are similar to those of GRBs observed at low/intermediate redshifts, suggesting that the mechanisms and progenitors that gave rise to this burst about 600,000,000 years after the Big Bang are not markedly different from those producing GRBs about 10,000,000,000 years later. PMID:19865166

  7. Observações das explosões cósmicas de raios gama GRB021004 e GRB021211 com o satélite HETE

    NASA Astrophysics Data System (ADS)

    Braga, J.; Ricker, G.; Hurley, K.; Lamb, D.; Grew, G.; et al.

    2003-08-01

    O High Energy Transient Explorer (HETE) é o primeiro satélite inteiramente dedicado ao estudo das explosões cósmicas de raios gama (ECRGs). Lançado em 9 de outubro de 2000, o HETE possui instrumentação capaz de observar as ECRGs desde o UV até raios gama e localizá-las com precisão de ~ 1-10 minutos de arco. As localizações das ECRGs detectadas são disseminadas rapidamente (em alguns segundos) pela Internet através de uma rede de estações de recepção ao longo do equador. A participação brasileira nesse projeto se dá através da montagem e operação de uma estação de recepção em Natal, RN, e da participação na equipe científica da missão. Neste trabalho são apresentados resultados da observação pelo HETE de duas ECRGs: GRB 021004 e GRB 021211. A GRB021004 foi detectada em raios gama pelo HETE em 4 de outubro de 2002 e localizada em raios-X em apenas 48 s, quando a emissão de raios gama ainda estava se processando. A explosão, relativamente brilhante e longa, durou aproximadamente 100 s. Um transiente óptico de magnitude 15 foi detectado no local da explosão nove minutos após o evento, e observações realizadas após 7 horas determinaram um desvio para o vermelho de absorção de 1,6. O GRB021004 foi o burst mais bem observado até o momento e suas observações em vários comprimentos de onda têm sido fundamentais para o aprimoramento dos modelos de ECRGs. O GRB21211, um burst brilhante e rico em raios-X, foi detectado em 11 de dezembro de 2002 e localizado em raios-X em 22 s após o início do evento. A duração do burst foi de 2,3 s em altas energias (85 a 400 keV) e de 8,5 s em baixas energias (2 a 10 keV). Caso essa explosão não tivesse sido rapidamente localizada pelo HETE, ela teria sido classificada como "opticamente escura", já que o transiente óptico decaiu rapidamente de R < 14 a R»19 dentro dos primeiros 20 minutos e já estava mais fraco do que R»23 depois de 24 horas da ocorrência do burst. Ser

  8. Identifying the Location in the Host Galaxy of Short GRB 1111l7A with the Chandra Sub- Arcsecond Position

    NASA Technical Reports Server (NTRS)

    Sakamoto, Takanori; Troja, E.; Aoki, K.; Guiriec, S.; Im, M.; Leloudas, G.; Malesani, D.; Melandri, A.; deUgartePostigo, A.; Urata, Y.; Xu, D.; DAvanzo, P.; Gorosabel, J.; Anderson, M. I.; Fynbo, J. P. U.; Aoki, K.; Sanchez-Ramirez, R.

    2012-01-01

    We present our successful program using Chandra for identifying the X-ray afterglow with sub-arcsecond accuracy for the short GRB 111117A d iscovered by Swift and Fermi. Thanks to our rapid target of opportuni ty request, Chandra clearly detected the X-ray afterglow, whereas no optical afterglow was found in deep optical observations. Instead, we clearly detect the host galaxy in optica; and also in near-infrared b ands. We found that the best photometric redshift fitofthe host is z = 1.31:(+0.46/-0.23) (90% confidence), making it one of the highest redshift short GRBs. Furthermore, we see an offset of 1.0+/-O.2 arcseco nds, which corresponds to 8.4+/-1.7 kpc aSBuming z= 1.31, between the host and the afterglow position. We discuss the importance of using Chandra for obtaining sub-arcsecond localization of the afterglow in X -rays for short GRBs to study GRB environments in great detail.

  9. The optical identification of events with poorly defined locations: the case of the Fermi GBM GRB 140801A

    NASA Astrophysics Data System (ADS)

    Lipunov, V. M.; Gorosabel, J.; Pruzhinskaya, M. V.; Postigo, A. de Ugarte; Pelassa, V.; Tsvetkova, A. E.; Sokolov, I. V.; Kann, D. A.; Xu, Dong; Gorbovskoy, E. S.; Krushinski, V. V.; Kornilov, V. G.; Balanutsa, P. V.; Boronina, S. V.; Budnev, N. M.; Cano, Z.; Castro-Tirado, A. J.; Chazov, V. V.; Connaughton, V.; Delvaux, C.; Frederiks, D. D.; Fynbo, J. F. U.; Gabovich, A. V.; Goldstein, A.; Greiner, J.; Gress, O. A.; Ivanov, K. I.; Jakobsson, P.; Klose, S.; Knust, F.; Komarova, V. N.; Konstantinov, E.; Krylov, A. V.; Kuvshinov, D. A.; Kuznetsov, A. S.; Lipunova, G. V.; Moskvitin, A. S.; Pal'shin, V. D.; Pandey, S. B.; Poleshchuk, V. A.; Schmidl, S.; Sergienko, Yu. P.; Sinyakov, E. V.; Schulze, S.; Sokolov, V. V.; Sokolova, T. N.; Sparre, M.; Thöne, C. C.; Tlatov, A. G.; Tyurina, N. V.; Ulanov, M. V.; Yazev, S. A.; Yurkov, V. V.

    2016-01-01

    We report the early discovery of the optical afterglow of gamma-ray burst (GRB) 140801A in the 137 deg2 3-σ error-box of the Fermi Gamma-ray Burst Monitor (GBM). MASTER is the only observatory that automatically reacts to all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart was discovered solely from its GBM localization. The optical afterglow of GRB 140801A was found by MASTER Global Robotic Net 53 s after receiving the alert, making it the fastest optical detection of a GRB from a GBM error-box. Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m Big Telescope Alt-azimuth of the Special Astrophysical Observatory of the Russian Academy of Sciences reveals a redshift of z = 1.32. We performed optical and near-infrared photometry of GRB 140801A using different telescopes with apertures ranging from 0.4 to 10.4 m. GRB 140801A is a typical burst in many ways. The rest-frame bolometric isotropic energy release and peak energy of the burst are E_iso = 5.54_{-0.24}^{+0.26} {×} 10^{52} erg and Ep, rest ≃ 280 keV, respectively, which is consistent with the Amati relation. The absence of a jet break in the optical light curve provides a lower limit on the half-opening angle of the jet θ = 6.1°. The observed Epeak is consistent with the limit derived from the Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis show that GRB 140801A could belong to the class of intermediate duration. The rapid detection of the optical counterpart of GRB 140801A is especially important regarding the upcoming experiments with large coordinate error-box areas.

  10. An Imaging and Spectroscopic Study of Four Strong Mg II Absorbers Revealed by GRB 060418

    NASA Astrophysics Data System (ADS)

    Pollack, L. K.; Chen, H.-W.; Prochaska, J. X.; Bloom, J. S.

    2009-08-01

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) gsim 1 Å revealed by the afterglow of GRB 060418 at z GRB = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z GRB, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Lyα systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at Δ θ lsim 3farcs5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity ≈0.1 - 1 L * at impact parameter of ρ lsim 10 h -1 kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of ρ = 2 - 12 h -1 kpc from the afterglow. At the afterglow's position, we derive a 2σ upper limit to the underlying star-formation rate intensity of 0.0074 M sun yr-1 kpc-2. Based in part on observations made with the NASA/ESA Hubble Space Telescope

  11. AN IMAGING AND SPECTROSCOPIC STUDY OF FOUR STRONG Mg II ABSORBERS REVEALED BY GRB 060418

    SciTech Connect

    Pollack, L. K.; Prochaska, J. X.; Chen, H.-W.; Bloom, J. S.

    2009-08-20

    We present results from an imaging and spectroscopic study of four strong Mg II absorbers of W(2796) {approx}> 1 A revealed by the afterglow of GRB 060418 at z{sub GRB} = 1.491. These absorbers, at z = 0.603, 0.656, 1.107, and z {sub GRB}, exhibit large ion abundances that suggest neutral gas columns characteristic of damped Ly{alpha} systems. The imaging data include optical images obtained using Low-Resolution Imaging Spectrometer (LRIS) on the Keck I telescope and using Advanced Camera for Surveys on board Hubble Space Telescope, and near-infrared H-band images obtained using Persson's Auxiliary Nasmyth Infrared Camera on the Magellan Baade Telescope and K'-band images obtained using NIRC2 with laser guide star adaptive optics on the Keck II telescope. These images reveal six distinct objects at {delta} {theta} {approx}< 3.''5 of the afterglow's position, two of which exhibit well-resolved mature disk morphology, one shows red colors, and three are blue compact sources. Follow-up spectroscopic observations using LRIS confirm that one of the disk galaxies coincides with the Mg II absorber at z = 0.656. The observed broadband spectral energy distributions of the second disk galaxy and the red source indicate that they are associated with the absorbers at z = 0.603 and z = 1.107, respectively. These results show that strong Mg II absorbers identified in gamma-ray burst (GRB) afterglow spectra are associated with typical galaxies of luminosity {approx}0.1 - 1 L{sub *} at impact parameter of {rho} {approx}< 10 h {sup -1} kpc. The close angular separation would preclude easy detections toward a bright quasar. Finally, we associate the remaining three blue compact sources with the GRB host galaxy, noting that they are likely star-forming knots located at projected distances of {rho} = 2 - 12 h {sup -1} kpc from the afterglow. At the afterglow's position, we derive a 2{sigma} upper limit to the underlying star-formation rate intensity of 0.0074 M{sub sun} yr{sup -1} kpc

  12. Signatures of particle acceleration on Gamma Ray Burst afterglow light curves

    NASA Astrophysics Data System (ADS)

    Petropoulou, M.

    2012-01-01

    We investigate the behavior of the X-ray lightcurves in the afterglow phase of Gamma Ray Bursts (GRB), after taking into account the maximum electron Lorentz factor (gamma_max) as an additional parameter of the problem. First, we treat gamma_max as a free parameter and we examine the lightcurves that one obtains for different values of the ratio gamma_max/gamma_min, where gamma_min is the minimum electron energy. We find that the lightcurves depend strongly on this ratio showing a variety of morphologies, with some having a strong resemblance to the observations. As a next step, we introduce particle acceleration and calculate gamma_max in a self-consistent way by balancing the energy losses with the energy gains of the accelerating electrons. The physical picture corresponds to particles injected at low energies and accelerated in the downstream region of the external GRB shock wave. We simulate that by introducing an acceleration term in the equation that describes the evolution of the electron distribution. We show some first results of the radiated synchrotron photon spectra obtained at various radii of the blast wave. Finally, we discuss possible implications of such 'one-zone' acceleration models for GRB afterglows.

  13. GRB host galaxy studies with VLT/X-shooter.

    NASA Astrophysics Data System (ADS)

    Vergani, S. D.

    We present the Italian-French GTO program dedicated to optical-NIR spectroscopy of long gamma-ray bursts (LGRB) host galaxies with VLT/X-shooter. To date most of the spectroscopical studies of GRB hosts are limited to z<1. At the end of the GTO period we will have collected the slit spectra of ˜ 30 GRB hosts: about a half at 0.8 < z < 1.5 and the remaining at z>1.5. Thanks to the unique capability of the X-shooter spectrograph we will be able to determine the properties of these objects (star formation rate, metallicity, extinction...) and compare them to those observed in absorption through the afterglow spectroscopy and to those of the galaxy samples studied in current galaxy surveys. Using the IFU X-shooter setup we will also perform the first IFU survey of GRB hosts, collecting the IFU spectra for a sample of ˜ 15 hosts at z<0.5. Here we will show some example of the studies we are carrying on with some preliminary results. Based on observations made with ESO Telescopes at Paranal Observatory under programmes ID 084.A-0260 (PI: J. Fynbo), 084.A-0631, 085.A-0795 and 086.A-0874 (PIs: S. Piranomonte and H. Flores).

  14. GRB 120422A/SN 2012bz: Bridging the gap between low- and high-luminosity gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Schulze, S.; Malesani, D.; Cucchiara, A.; Tanvir, N. R.; Krühler, T.; de Ugarte Postigo, A.; Leloudas, G.; Lyman, J.; Bersier, D.; Wiersema, K.; Perley, D. A.; Schady, P.; Gorosabel, J.; Anderson, J. P.; Castro-Tirado, A. J.; Cenko, S. B.; De Cia, A.; Ellerbroek, L. E.; Fynbo, J. P. U.; Greiner, J.; Hjorth, J.; Kann, D. A.; Kaper, L.; Klose, S.; Levan, A. J.; Martín, S.; O'Brien, P. T.; Page, K. L.; Pignata, G.; Rapaport, S.; Sánchez-Ramírez, R.; Sollerman, J.; Smith, I. A.; Sparre, M.; Thöne, C. C.; Watson, D. J.; Xu, D.; Bauer, F. E.; Bayliss, M.; Björnsson, G.; Bremer, M.; Cano, Z.; Covino, S.; D'Elia, V.; Frail, D. A.; Geier, S.; Goldoni, P.; Hartoog, O. E.; Jakobsson, P.; Korhonen, H.; Lee, K. Y.; Milvang-Jensen, B.; Nardini, M.; Nicuesa Guelbenzu, A.; Oguri, M.; Pandey, S. B.; Petitpas, G.; Rossi, A.; Sandberg, A.; Schmidl, S.; Tagliaferri, G.; Tilanus, R. P. J.; Winters, J. M.; Wright, D.; Wuyts, E.

    2014-06-01

    Context. At low redshift, a handful of gamma-ray bursts (GRBs) have been discovered with luminosities that are substantially lower (Liso ≲ 1048.5 erg s-1) than the average of more distant ones (Liso ≳ 1049.5 erg s-1). It has been suggested that the properties of several low-luminosity (low-L) GRBs are due to shock break-out, as opposed to the emission from ultrarelativistic jets. This has led to much debate about how the populations are connected. Aims: The burst at redshift z = 0.283 from 2012 April 22 is one of the very few examples of intermediate-L GRBs with a γ-ray luminosity of Liso ~ 1049.6-49.9 erg s-1 that have been detected up to now. With the robust detection of its accompanying supernova SN 2012bz, it has the potential to answer important questions on the origin of low- and high-L GRBs and the GRB-SN connection. Methods: We carried out a spectroscopy campaign using medium- and low-resolution spectrographs with 6-10-m class telescopes, which covered a time span of 37.3 days, and a multi-wavelength imaging campaign, which ranged from radio to X-ray energies over a duration of ~270 days. Furthermore, we used a tuneable filter that is centred at Hα to map star-formation in the host and the surrounding galaxies. We used these data to extract and model the properties of different radiation components and fitted the spectral energy distribution to extract the properties of the host galaxy. Results: Modelling the light curve and spectral energy distribution from the radio to the X-rays revealed that the blast wave expanded with an initial Lorentz factor of Γ0 ~ 50, which is a low value in comparison to high-L GRBs, and that the afterglow had an exceptionally low peak luminosity density of ≲2 × 1030 erg s-1 Hz-1 in the sub-mm. Because of the weak afterglow component, we were able to recover the signature of a shock break-out in an event that was not a genuine low-L GRB for the first time. At 1.4 hr after the burst, the stellar envelope had a blackbody

  15. The Needle in the 100 deg2 Haystack: Uncovering Afterglows of Fermi GRBs with the Palomar Transient Factory

    NASA Astrophysics Data System (ADS)

    Singer, Leo P.; Kasliwal, Mansi M.; Cenko, S. Bradley; Perley, Daniel A.; Anderson, Gemma E.; Anupama, G. C.; Arcavi, Iair; Bhalerao, Varun; Bue, Brian D.; Cao, Yi; Connaughton, Valerie; Corsi, Alessandra; Cucchiara, Antonino; Fender, Rob P.; Fox, Derek B.; Gehrels, Neil; Goldstein, Adam; Gorosabel, J.; Horesh, Assaf; Hurley, Kevin; Johansson, Joel; Kann, D. A.; Kouveliotou, Chryssa; Huang, Kuiyun; Kulkarni, S. R.; Masci, Frank; Nugent, Peter; Rau, Arne; Rebbapragada, Umaa D.; Staley, Tim D.; Svinkin, Dmitry; Thöne, C. C.; de Ugarte Postigo, A.; Urata, Yuji; Weinstein, Alan

    2015-06-01

    The Fermi Gamma-ray Space Telescope has greatly expanded the number and energy window of observations of gamma-ray bursts (GRBs). However, the coarse localizations of tens to a hundred square degrees provided by the Fermi GRB Monitor instrument have posed a formidable obstacle to locating the bursts’ host galaxies, measuring their redshifts, and tracking their panchromatic afterglows. We have built a target-of-opportunity mode for the intermediate Palomar Transient Factory in order to perform targeted searches for Fermi afterglows. Here, we present the results of one year of this program: 8 afterglow discoveries out of 35 searches. Two of the bursts with detected afterglows (GRBs 130702A and 140606B) were at low redshift (z = 0.145 and 0.384, respectively) and had spectroscopically confirmed broad-line Type Ic supernovae. We present our broadband follow-up including spectroscopy as well as X-ray, UV, optical, millimeter, and radio observations. We study possible selection effects in the context of the total Fermi and Swift GRB samples. We identify one new outlier on the Amati relation. We find that two bursts are consistent with a mildly relativistic shock breaking out from the progenitor star rather than the ultra-relativistic internal shock mechanism that powers standard cosmological bursts. Finally, in the context of the Zwicky Transient Facility, we discuss how we will continue to expand this effort to find optical counterparts of binary neutron star mergers that may soon be detected by Advanced LIGO and Virgo.

  16. Radio afterglows and host galaxies of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Li, Long-Biao; Zhang, Zhi-Bin; Huang, Yong-Feng; Wu, Xue-Feng; Kong, Si-Wei; Li, Di; Chang, Heon-Young; Choi, Chul-Sung

    2015-08-01

    Considering the contribution of emission from the host galaxies of gamma-ray bursts (GRBs) to radio afterglows, we investigate the effect of host galaxies on observations statistically. For the three types of event, i.e. low-luminosity, standard and high-luminosity GRBs, it is found that a tight correlation exists between the ratio of the radio flux (RRF) of the host galaxy to the total radio peak emission and the observational frequency. Towards lower frequencies, in particular, the contribution from the host increases significantly. The correlation can be used to obtain a useful estimate for the radio brightness of those host galaxies that only have very limited radio afterglow data. Using this prediction, we reconsidered the theoretical radio afterglow light curves for four kinds of event: high-luminosity, low-luminosity, standard and failed GRBs, taking into account the contribution from host galaxies and aiming to explore the detectability of these events by the Five-hundred-metre Aperture Spherical radio Telescope (FAST). Lying at a typical redshift of z = 1, most of the events can be detected easily by FAST. For the less fierce low-luminosity GRBs, their radio afterglows are not strong enough to exceed the sensitivity limit of FAST at such distances. However, since a large number of low-luminosity bursts actually happen very near to us, it is expected that FAST will still be able to detect many of them.

  17. Gamma-Ray Bursts: Afterglows and Central Engines

    NASA Astrophysics Data System (ADS)

    Cheng, K. S.; Lu, T.

    2001-01-01

    Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BASTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmological distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.

  18. Classification, Follow-up, and Analysis of GRBs and their Early-time NIR/Optical Afterglows

    NASA Astrophysics Data System (ADS)

    Morgan, Adam; Bloom, J. S.; Perley, D. A.; Christian, P.; Richards, J.; Cenko, S. B.; Klein, C. R.

    2014-01-01

    In the study of astronomical transients, achieving knowledge from discovery is a multifaceted process which includes real-time classification to identify new events of interest, deep, multi-wavelength follow-up of individual events, and the global analysis of multi-event catalogs. Here we present a body of work encompassing each of these steps as applied to the study of gamma-ray bursts (GRBs). First, we present our work on utilizing machine-learning algorithms on early-time metrics from the Swift satellite to inform the resource allocation of follow-up telescopes in order to optimize time spent on high-redshift GRB candidates. Next, we show broadband observations and analysis of the early-time afterglow of GRB 120119A, which exhibits extreme red-to-blue color change in the first few minutes after the trigger. Model fits of this color change reveal among the best support yet for the direct detection of dust destruction in the local environment of a GRB. Finally, we present results from the PAIRITEL early-time near-infrared (NIR) afterglow catalog. The 1.3 meter PAIRITEL has autonomously observed 15 GRBs in under 4 minutes after the trigger, yielding a homogenous sample of early-time JHKs light curves. Our analysis of these events provides constraints on the NIR GRB luminosity function, direct measurements of early-time NIR color change, and constraints on burst energetics.

  19. GRB Simulations in GLAST

    SciTech Connect

    Omodei, Nicola; Battelino, Milan; Komin, Nukri; Longo, Francesco; McEnery, Julie; Norris, Jay; Ryde, Felix

    2007-05-01

    The Gamma-ray Large Area Space Telescope (GLAST), scheduled to be launched in fall of 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT) is a pair conversion telescope built with a high precision silicon tracker, a segmented CsI electromagnetic calorimeter and a plastic anticoincidence shield. The LAT will survey the sky in the energy range between 20 MeV to more than 300 GeV, shedding light on many issues left open by its highly successful predecessor EGRET. LAT will observe Gamma-Ray Bursts (GRB) in an energy range never explored before; to tie these frontier observations to the better-known properties at lower energies, a second instrument, the GLAST Burst Monitor (GBM) will provide important spectra and timing in the 10 keV to 30 MeV range. We briefly present the instruments onboard the GLAST satellite, their synergy in the GRB observations and the work done so far by the collaboration in simulation, analysis, and GRB sensitivity estimation.

  20. GRB Simulations in GLAST

    SciTech Connect

    Omodei, Nicola; Battelino, Milan; Komin, Nukri; Longo, Francesco; McEnery, Julie; Ryde, Felix; /Denver U.

    2007-10-22

    The Gamma-ray Large Area Space Telescope (GLAST), scheduled to be launched in fall of 2007, is the next generation satellite for high-energy gamma-ray astronomy. The Large Area Telescope (LAT) is a pair conversion telescope built with a high precision silicon tracker, a segmented CsI electromagnetic calorimeter and a plastic anticoincidence shield. The LAT will survey the sky in the energy range between 20 MeV to more than 300 GeV, shedding light on many issues left open by its highly successful predecessor EGRET. LAT will observe Gamma-Ray Bursts (GRB) in an energy range never explored before; to tie these frontier observations to the better-known properties at lower energies, a second instrument, the GLAST Burst Monitor (GBM) will provide important spectra and timing in the 10 keV to 30 MeV range. We briefly present the instruments onboard the GLAST satellite, their synergy in the GRB observations and the work done so far by the collaboration in simulation, analysis, and GRB sensitivity estimation.

  1. Classification, Follow-Up, and Analysis of Gamma-Ray Bursts and their Early-Time Near-Infrared/Optical Afterglows

    NASA Astrophysics Data System (ADS)

    Morgan, Adam Nolan

    In the study of astronomical transients, deriving knowledge from discovery is a multifaceted process that includes real-time classification to identify new events of interest, deep, multi-wavelength follow-up of individual events, and the global analysis of multi-event catalogs. Here we present a body of work encompassing each of these steps as applied to the study of gamma-ray bursts (GRBs). First, we present our work on utilizing machine-learning algorithms on early-time metrics from the Swift satellite to inform the resource allocation of follow-up telescopes in order to optimize time spent on high-redshift GRB candidates. Next, we show broadband observations and analysis of the early-time afterglow of GRB 120119A, utilizing data obtained with a dozen telescope facilities both in space and on the ground. This event exhibits extreme red-to-blue color change in the first few minutes after the trigger at levels unseen in prior afterglows, and our model fits of this phenomenon reveal the best support yet for the direct detection of dust destruction in the local environment of a GRB. Finally, we present results from the PAIRITEL early-time near-infrared (NIR) afterglow catalog. The 1.3 meter PAIRITEL has autonomously observed 14 GRBs in under 3 minutes after the burst, yielding a homogenous sample of early-time JHKs light curves. Our analysis of these events provides constraints on the early-time NIR GRB afterglow luminosity function and gives insight into the importance of dust extinction in the suppression of some optical afterglows.

  2. The Late Peaking Afterglow of GR8 100418A

    NASA Technical Reports Server (NTRS)

    Marshall, Frank; Antonelli, L. A.; Burrows, D. N.; Covino, S.; dePasquale, M.; Evans, P. A.; Fugazza, D.; Holland, S. T.; Liang, E. W.; OBrien, P. T.; Osborne, J. P.; Pagani, C.; Sakamoto, T.; Siegel, M. H.; Wu, X. F.; Zhang, B.

    2010-01-01

    GRB 100418A is a long Gamma-Ray Burst at redshift z=0.6235 discovered with the Swift Gamma-Ray Burst Explorer with unusual optical and X-ray light curves ' After an initial short-lived, rapid decline in X-rays, the optical and X-ray light curves observed with Swift