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Sample records for 500th gamma-ray burst

  1. Swift's 500th Gamma Ray Burst

    NASA Image and Video Library

    On April 13, 2010, NASA's Swift Gamma-ray Burst Explorer satellite discovered its 500th burst. Swift's main job is to quickly localize each gamma-ray burst (GRB), report its position so that others...

  2. Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Kouveliotou, Chryssa; Wijers, Ralph A. M. J.; Woosley, Stan

    2012-11-01

    Prologue C. Kouveliotou, R. A . M. J. Wijers and S. E. Woosley; 1. The discovery of the gamma-ray burst phenomenon R. W. Klebesadel; 2. Instrumental principles E. E. Fenimore; 3. The BATSE era G. J. Fishman and C. A. Meegan; 4. The cosmological era L. Piro and K. Hurley; 5. The Swift era N. Gehrels and D. N. Burrows; 6. Discoveries enabled by multi-wavelength afterglow observations of gamma-ray bursts J. Greiner; 7. Prompt emission from gamma-ray bursts T. Piran, R. Sari and R. Mochkovitch; 8. Basic gamma-ray burst afterglows P. Mészáros and R. A. M. J. Wijers; 9. The GRB-supernova connection J. Hjorth and J. S. Bloom; 10. Models for gamma-ray burst progenitors and central engines S. E. Woosley; 11. Jets and gamma-ray burst unification schemes J. Granot and E. Ramirez-Ruiz; 12. High-energy cosmic rays and neutrinos E. Waxman; 13. Long gamma-ray burst host galaxies and their environments J. P. U. Fynbo, D. Malesani and P. Jakobsson; 14. Gamma-ray burst cosmology V. Bromm and A. Loeb; 15. Epilogue R. D. Blandford; Index.

  3. Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day ,last typically lOs of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  4. Gamma Ray Bursts - Observations

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

    We are in an exciting period of discovery for gamma-ray bursts. The Swift observatory is detecting 100 bursts per year, providing arcsecond localizations and sensitive observations of the prompt and afterglow emission. The Fermi observatory is observing 250 bursts per year with its medium-energy GRB instrument and about 10 bursts per year with its high-energy LAT instrument. In addition, rapid-response telescopes on the ground are providing new capabilities to study optical emission during the prompt phase and spectral signatures of the host galaxies. The combined data set is enabling great advances in our understanding of GRBs including afterglow physics, short burst origin, and high energy emission.

  5. Gamma-ray burst observations

    NASA Technical Reports Server (NTRS)

    Atteia, J.-L.

    1993-01-01

    The most important observational characteristics of gamma-ray bursts are reviewed, with emphasis on X-ray and gamma-ray data. The observations are used to derive some basic properties of the sources. The sources are found to be isotropically distributed; the burster population is limited in space, and the edge of the distribution is visible.

  6. On the origin of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Vahia, M. N.; Rao, A. R.

    1988-03-01

    It is argued that observations of gamma ray bursts show that the neutron star model is not tenable. A similarity between gamma ray burst characteristics and solar hard X-ray flares is established. The temporal and spectral features observed in the gamma ray bursts are also seen in the solar hard X-ray flares. The only distinction is in the energy contents of the two. Gamma ray bursts may originate from sources which have Sun-like activity. Large scale Sun-like activity is observed in flare stars, RS CVn binaries, and cataclysmic variables, grouped together as magnetically active stellar systems. These systems have enough energy to produce gamma ray bursts. Positional identification between the gamma ray burst error boxes and the magnetically active stellar systems produces an association of 46 objects with 36 error boxes with a probability of chance coincidence of 10 to the minus 10th power. A gamma ray burst that has a spatial and temporal correlation to a soft X-ray flare associated with a magnetically active stellar system and another time coincidence where the gamma ray burst location is not known to be found. Gamma ray bursts should be considered the stellar equivalent of the solar hard X-ray burst. gamma ray burst location is not known are found. Gamma ray bursts should be considered as stellar equivalents of solar hard X-ray bursts.

  7. Gamma-ray burst populations

    NASA Astrophysics Data System (ADS)

    Virgili, Francisco Javier

    Over the last fifty years the field of gamma-ray bursts has shown incredible growth, but the amassing of data has also left observers and theorists alike wondering about some of the basic questions surrounding these phenomena. Additionally, these events show remarkable individuality and extrema, ranging in redshift throughout the observable universe and over ten orders of magnitude in energy. This work focuses on analyzing groups of bursts that are different from the general trend and trying to understand whether these bursts are from different intrinsic populations and if so, what can be said about their progenitors. This is achieved through numerical Monte Carlo simulations and statistical inference in conjunction with current GRB observations. Chapter 1 gives a general introduction of gamma-ray burst theory and observations in a semi-historical context. Chapter 2 provides an introduction to the theory and practical issues surrounding the numerical simulations and statistics. Chapters 3--5 are each dedicated to a specific problem relating to a different type of GRB population: high-luminosity v. low-luminosity bursts, constraints from high-redshift bursts, and Type I v. Type II bursts. Chapter 6 follows with concluding remarks.

  8. Dark gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Brdar, Vedran; Kopp, Joachim; Liu, Jia

    2017-03-01

    Many theories of dark matter (DM) predict that DM particles can be captured by stars via scattering on ordinary matter. They subsequently condense into a DM core close to the center of the star and eventually annihilate. In this work, we trace DM capture and annihilation rates throughout the life of a massive star and show that this evolution culminates in an intense annihilation burst coincident with the death of the star in a core collapse supernova. The reason is that, along with the stellar interior, also its DM core heats up and contracts, so that the DM density increases rapidly during the final stages of stellar evolution. We argue that, counterintuitively, the annihilation burst is more intense if DM annihilation is a p -wave process than for s -wave annihilation because in the former case, more DM particles survive until the supernova. If among the DM annihilation products are particles like dark photons that can escape the exploding star and decay to standard model particles later, the annihilation burst results in a flash of gamma rays accompanying the supernova. For a galactic supernova, this "dark gamma-ray burst" may be observable in the Čerenkov Telescope Array.

  9. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2004-01-01

    Gamma-ray bursts remain one of the greatest mysteries in astrophysics. Observations of gamma-ray bursts made by the BATSE experiment on the Compton Gamma-Ray Observatory will be described. Most workers in the field now believe that they originate from cosmological distances. This view has been reinforced by observations this year of several optical afterglow counterparts to gamma-ray bursts. A summary of these recent discoveries will be presented, along with their implications for models of the burst emission mechanism and the energy source of the bursts.

  10. Neutrino bursts from gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Paczynski, Bohdan; Xu, Guohong

    1994-01-01

    If gamma-ray bursts originate at cosmological distances, as strongly indicated by the results from Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory (CGRO), then ultrarelativistic ejecta are the likely consequence of the highly super-Eddington luminosity of the sources. If the energy injection rate varies with time, then the Lorentz factor of the wind also varies, and the shells of ejected matter collide with each other. The collisions between baryons produce pions which decay into high-energy photons, electrons, electron positron pairs, and neutrino pairs. The bulk Lorentz factor of approximately 300 is required if our model is to be compatible with the observed millisecond variability. The strongest gamma-ray bursts are observed to deliver approximately 10(exp -4) ergs/sq cm in 100-200 keV photons. In our scenario more energy may be delivered in a neutrino burst. Typical neutrinos may be approximately 30 GeV if the protons have a Maxwellian energy distribution, and up to approximately TeV if the protons have a power-law distribution. Such neutrino bursts are close to the detection limit of the DUMAND II experiment.

  11. GAMCIT: A gamma ray burst detector

    NASA Technical Reports Server (NTRS)

    Surka, Derek M.; Grunsfeld, John M.; Warneke, Brett A.

    1992-01-01

    The origin of celestial gamma ray bursts remains one of the great mysteries of modern astrophysics. The GAMCIT Get-Away-Special payload is designed to provide new and unique data in the search for the sources of gamma ray bursts. GAMCIT consists of three gamma ray detectors, an optical CCD camera, and an intelligent electronics system. This paper describes the major components of the system, including the electronics and structural designs.

  12. Gamma ray bursts inner engines

    NASA Astrophysics Data System (ADS)

    Staff, Jan Erling

    Long gamma ray bursts (GRBs) are brief durations of intense, highly variable gamma radiation coming from point like sources in the Universe. GRBs have been seen in connection with Type 1c supernovae. Their isotropical equivalent energy released in gamma rays is in some cases above 10 54 erg, but the engine creating this energy is unknown. In this thesis several models for the engine are explored. It is shown that cannonballs can in principle form from hyperaccreting disks, however the cannonball model requires almost all supernovae to create cannonballs, and our finding then implies that a hyperaccreting disk is a natural consequence in most supernovae, a notion which remains to be confirmed. General relativistic magnetohydrodynamic simulations of the collapsar model have been performed. Within our setup we found that the duration of the collapsar is too short to explain GRBs, and the energy output is not sufficient. Also the supernova connection could not be explained. I find that the more likely candidate for the GRB engine is an accreting quark star. A quark star has a maximum mass, if the mass increases above this the star will collapse to a black hole. This allows for a two stage engine that might be able to explain features observed in GRBs.

  13. Observations of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1995-01-01

    Some basic observed properties of gamma-ray bursts are reviewed. Although some properties were known 25 years ago, new and more detailed observations have been made by the Compton Observatory in the past three years. The new observation with the greatest impact has been the observed isotropic distribution of bursts along with a deficiency of weak bursts which would be expected from a homogeneous burst distribution. This is not compatible with any known Galactic population of objects. Gamma-ray bursts show an enormous variety of burst morphologies and a wide spread in burst durations. The spectra of gamma-ray bursts are characterized by rapid variations and peak power which is almost entirely in the gamma-ray energy range. Delayed gamma-ray burst photons extending to GeV energies have been detected for the first time. A time dilation effect has also been reported to be observed in gamma-ray, bursts. The observation of a gamma-ray burst counterpart in another wavelength region has yet to be made.

  14. Origin of the gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Vahia, M. N.; Rao, A. R.

    1988-12-01

    The authors establish a similarity between the gamma ray burst characteristics and solar hard X-ray flares. They show that all the temporal and spectral features observed in gamma ray bursts are also seen in solar hard X-ray flares. The only distinction is in the energy contents of the two. The authors suggest that the gamma-ray bursts originate from sources which have Sun like activity. Large scale Sun like activity has been observed in flare stars, RS CVn binaries and cataclysmic variables which are grouped together as the magnetically active stellar systems. The energetics of such systems is discussed and it is shown that these systems have enough energy to produce gamma-ray bursts. The authors then attempt positional identification between gamma-ray burst error boxes and the magnetically active stellar systems and find an association of 34 objects.

  15. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    1998-01-01

    Gamma-ray bursts remain on of the greatest mysteries in astrophysics in spite of recent observational advances and intense theoretical work. Although some of the basic properties of bursts were known 25 years ago, new and more detailed observations have been made by the BATSE (Burst and Transient Source Experiment) experiment on the Compton Gamma Ray Observatory in the past five years. Recent observations of bursts and some proposed models will be discussed.

  16. Modeling gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Maxham, Amanda

    Discovered serendipitously in the late 1960s, gamma-ray bursts (GRBs) are huge explosions of energy that happen at cosmological distances. They provide a grand physical playground to those who study them, from relativistic effects such as beaming, jets, shocks and blastwaves to radiation mechanisms such as synchrotron radiation to galatic and stellar populations and history. Through the Swift and Fermi space telescopes dedicated to observing GRBs over a wide range of energies (from keV to GeV), combined with accurate pinpointing that allows ground based follow-up observations in the optical, infrared and radio, a rich tapestry of GRB observations has emerged. The general picture is of a mysterious central engine (CE) probably composed of a black hole or neutron star that ejects relativistic shells of matter into intense magnetic fields. These shells collide and combine, releasing energy in "internal shocks" accounting for the prompt emission and flaring we see and the "external shock" or plowing of the first blastwave into the ambient surrounding medium has well-explained the afterglow radiation. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We have also included a blastwave model, which can constrain X-ray flares and explain the origin of high energy (GeV) emission seen by the Fermi telescope. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We pay special attention to the time history of central engine activity, internal shocks, and observed flares. We calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary

  17. Unveiling the secrets of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Gomboc, Andreja

    2012-07-01

    Gamma Ray Bursts are unpredictable and brief flashes of gamma rays that occur about once a day in random locations in the sky. Since gamma rays do not penetrate the Earth's atmosphere, they are detected by satellites, which automatically trigger ground-based telescopes for follow-up observations at longer wavelengths. In this introduction to Gamma Ray Bursts we review how building a multi-wavelength picture of these events has revealed that they are the most energetic explosions since the Big Bang and are connected with stellar deaths in other galaxies. However, in spite of exceptional observational and theoretical progress in the last 15 years, recent observations raise many questions which challenge our understanding of these elusive phenomena. Gamma Ray Bursts therefore remain one of the hottest topics in modern astrophysics.

  18. ASTRONOMY: Neighborhood Gamma Ray Burst Boosts Theory.

    PubMed

    Schilling, G

    2000-07-07

    Titanic explosions that emit powerful flashes of energetic gamma rays are one of astronomy's hottest mysteries. Now an analysis of the nearest gamma ray burst yet detected has added weight to the popular theory that they are expelled during the death throes of supermassive stars.

  19. Gamma-ray burst cosmology

    NASA Astrophysics Data System (ADS)

    Wang, F. Y.; Dai, Z. G.; Liang, E. W.

    2015-08-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to 8.8 × 1054 erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it is possible to extract intergalactic medium (IGM) absorption features. We also present the capability of high-redshift GRBs to probe the pre-galactic metal enrichment and the first stars.

  20. Gamma-Ray Burst Progenitors

    NASA Astrophysics Data System (ADS)

    Levan, Andrew; Crowther, Paul; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-12-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; (i) direct observations of GRBs and their host galaxies, (ii) parameters derived from modelling, both via population synthesis and direct numerical simulation and (iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous and super-luminous supernovae to long and short GRBs.

  1. Overview Animation of Gamma-ray Burst

    NASA Image and Video Library

    Gamma-ray bursts are the most luminous explosions in the cosmos. Astronomers think most occur when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a b...

  2. POPULATION SYNTHESIS AND GAMMA RAY BURST PROGENITORS

    SciTech Connect

    C. L. FREYER

    2000-12-11

    Population synthesis studies of binaries are always limited by a myriad of uncertainties from the poorly understood effects of binary mass transfer and common envelope evolution to the many uncertainties that still remain in stellar evolution. But the importance of these uncertainties depends both upon the objects being studied and the questions asked about these objects. Here I review the most critical uncertainties in the population synthesis of gamma-ray burst progenitors. With a better understanding of these uncertainties, binary population synthesis can become a powerful tool in understanding, and constraining, gamma-ray burst models. In turn, as gamma-ray bursts become more important as cosmological probes, binary population synthesis of gamma-ray burst progenitors becomes an important tool in cosmology.

  3. Supernovae and gamma-ray bursts connection

    SciTech Connect

    Valle, Massimo Della

    2015-12-17

    I’ll review the status of the Supernova/Gamma-Ray Burst connection. Several pieces of evidence suggest that long duration Gamma-ray Bursts are associated with bright SNe-Ic. However recent works suggest that GRBs might be produced in tight binary systems composed of a massive carbon-oxygen cores and a neutron star companion. Current estimates of the SN and GRB rates yield a ratio GRB/SNe-Ibc in the range ∼ 0.4% − 3%.

  4. Gamma-Ray Burst Physics with GLAST

    SciTech Connect

    Omodei, N.; /INFN, Pisa

    2006-10-06

    The Gamma-ray Large Area Space Telescope (GLAST) is an international space mission that will study the cosmos in the energy range 10 keV-300 GeV, the upper end of which is one of the last poorly observed region of the celestial electromagnetic spectrum. The ancestor of the GLAST/LAT was the Energetic Gamma Ray Experiment Telescope (EGRET) detector, which flew onboard the Compton Gamma Ray Observatory (CGRO). The amount of information and the step forward that the high energy astrophysics made thanks to its 9 years of observations are impressive. Nevertheless, EGRET uncovered the tip of the iceberg, raising many questions, and it is in the light of EGRET's results that the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope, the Large Area Telescope (LAT) vastly more capable than instruments own previously, as well as a secondary instrument, the GLAST Bursts Monitor, or GBM, to augment the study of gamma-ray bursts. Gamma-Ray Bursts (GRBs) science is one of the most exciting challenges for the GLAST mission, exploring the high energy emission of one of the most intense phenomena in the sky, shading light on various problems: from the acceleration of particles to the emission processes, to more exotic physics like Quantum Gravity effect. In this paper we report the work done so far in the simulation development as well as the study of the LAT sensitivity to GRB.

  5. Microsecond flares in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Cohen, Justin; Teegarden, Bonnard J.; Cline, Thomas L.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Paciesas, William S.; Pendleton, Geoffrey N.; Matteson, James L.

    1993-01-01

    It has been suggested that gamma-ray burst light curves may consist of many superposed flares with a duration shorter than 30/microsec. If true, the implications for the interpretation of burst data are enormous. With the launch of the Compton Gamma-Ray Observatory, four predictions of Mitrofanov's (1989) suggestion can be tested. Our results which contradict this suggestion are (1) the photon arrival times are not correlated between independent detectors, (2) the spectral hardness and intensity does not depend on the detector area, (3) the bursts seen by detectors which measure photon positions do not see microsecond flares, and (4) burst positions deduced from detectors with different projected areas are close to the positions deduced from time-of-flight differences between separated spacecraft. We conclude, therefore, that gamma-ray bursts are not composed of microsecond flares.

  6. Supernovae and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Panagia, Nino; Sahu, Kailash

    2001-07-01

    Participants; Preface; Gamma-ray burst-supernova relation B. Paczynski; Observations of gamma-ray bursts G. Fishman; Fireballs T. Piran; Gamma-ray mechanisms M. Rees; Prompt optical emission from gamma-ray bursts R. Kehoe, C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson, T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, K. Hurley, B. Lee, S. Marshall, T. McKay, A. Pawl, L. Piro, B. Priedhorsky, J. Szymanski and J. Wren; X-ray afterglows of gamma-ray bursts L. Piro; The first year of optical-IR observations of SN1998bw I. Danziger, T. Augusteijn, J. Brewer, E. Cappellaro, V. Doublier, T. Galama, J. Gonzalez, O. Hainaut, B. Leibundgut, C. Lidman, P. Mazzali, K. Nomoto, F. Patat, J. Spyromilio, M. Turatto, J. Van Paradijs, P. Vreeswijk and J. Walsh; X-ray emission of Supernova 1998bw in the error box of GRB980425 E. Pian; Direct analysis of spectra of type Ic supernovae D. Branch; The interaction of supernovae and gamma-ray bursts with their surroundings R. Chevalier; Magnetars, soft gamma-ray repeaters and gamma-ray bursts A. Harding; Super-luminous supernova remnants Y. -H. Chu, C. -H. Chen and S. -P. Lai; The properties of hypernovae: SNe Ic 1998bw, 1997ef, and SN IIn 1997cy K. Nomoto, P. Mazzali, T. Nakamura, K. Iwanmoto, K. Maeda, T. Suzuki, M. Turatto, I. Danziger and F. Patat; Collapsars, Gamma-Ray Bursts, and Supernovae S. Woosley, A. MacFadyen and A. Heger; Pre-supernova evolution of massive stars N. Panagia and G. Bono; Radio supernovae and GRB 980425 K. Weiler, N. Panagia, R. Sramek, S. Van Dyk, M. Montes and C. Lacey; Models for Ia supernovae and evolutionary effects P. Hoflich and I. Dominguez; Deflagration to detonation A. Khokhlov; Universality in SN Iae and the Phillips relation D. Arnett; Abundances from supernovae F. -K. Thielemann, F. Brachwitz, C. Freiburghaus, S. Rosswog, K. Iwamoto, T. Nakamura, K. Nomoto, H. Umeda, K. Langanke, G. Martinez-Pinedo, D. Dean, W. Hix and M. Strayer; Sne, GRBs, and the

  7. On Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Ruffini, R.; Bernardini, M. G.; Bianco, C. L.; Caito, L.; Chardonnet, P.; Cherubini, C.; Dainotti, M. G.; Fraschetti, F.; Geralico, A.; Guida, R.; Patricelli, B.; Rotondo, M.; Rueda Hernandez, J. A.; Vereshchagin, G.; Xue, S.-S.

    2008-09-01

    We show by example how the uncoding of Gamma-Ray Bursts (GRBs) offers unprecedented possibilities to foster new knowledge in fundamental physics and in astrophysics. After recalling some of the classic work on vacuum polarization in uniform electric fields by Klein, Sauter, Heisenberg, Euler and Schwinger, we summarize some of the efforts to observe these effects in heavy ions and high energy ion collisions. We then turn to the theory of vacuum polarization around a Kerr-Newman black hole, leading to the extraction of the blackholic energy, to the concept of dyadosphere and dyadotorus, and to the creation of an electron-positron-photon plasma. We then present a new theoretical approach encompassing the physics of neutron stars and heavy nuclei. It is shown that configurations of nuclear matter in bulk with global charge neutrality can exist on macroscopic scales and with electric fields close to the critical value near their surfaces. These configurations may represent an initial condition for the process of gravitational collapse, leading to the creation of an electron-positron-photon plasma: the basic self-accelerating system explaining both the energetics and the high energy Lorentz factor observed in GRBs. We then turn to recall the two basic interpretational paradigms of our GRB model: 1) the Relative Space-Time Transformation (RSTT) paradigm and 2) the Interpretation of the Burst Structure (IBS) paradigm. These paradigms lead to a "canonical" GRB light curve formed from two different components: a Proper-GRB (P-GRB) and an extended afterglow comprising a raising part, a peak, and a decaying tail. When the P-GRB is energetically predominant we have a "genuine" short GRB, while when the afterglow is energetically predominant we have a so-called long GRB or a "fake" short GRB. We compare and contrast the description of the relativistic expansion of the electron-positron plasma within our approach and within the other ones in the current literature. We then turn

  8. Physics issues of gamma ray burst emissions

    NASA Technical Reports Server (NTRS)

    Liang, Edison

    1987-01-01

    The critical physics issues in the interpretation of gamma-ray-burst spectra are reviewed. An attempt is made to define the emission-region parameter space satisfying the maximum number of observational and theoretical constraints. Also discussed are the physical mechanisms responsible for the bursts that are most consistent with the above parameter space.

  9. Fuzzy correlations of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Hartmann, Dieter H.; Linder, Eric V.; Blumenthal, George R.

    1991-01-01

    The origin of gamma-ray bursts is not known, both in the sense of the nature of the source emitting the radiation and literally, the position of the burst on the sky. Lacking unambiguously identified counterparts in any wavelength band studied to date, statistical approaches are required to determine the burster distance scale. Angular correlation analysis is one of the most powerful tools in this regard. However, poor detector resolution gives large localization errors, effectively beam smearing the positions. The resulting fuzzy angular correlation function is investigated and the generic isotropization that smearing induces on any intrinsic clustering is discussed. In particular, the extent to which gamma-ray burst observations by the BATSE detector aboard the Gamma-Ray Observatory might recover an intrinsic source correlation is investigated.

  10. Stirling Colgate and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Lamb, Donald

    2014-10-01

    Even before the discovery of gamma-ray bursts (GRBs), Stirling Colgate proposed that bursts of x rays and gamma rays might be produced by a relativistic shock created in the supernova explosion of a massive star. We trace the scientific story of GRBs from their detection to the present, highlighting along the way Stirling's interest in them and his efforts to understand them. We summarize our current understanding that short, soft, repeating bursts are produced by magnetic neutron stars; short, hard bursts are produced by the mergers of neutron star-neutron star binaries; and long, hard bursts are produced by the core collapse of massive stars that have lost their hydrogen and helium envelopes. We then discuss some important open questions about GRBs and how they might be answered. We conclude by describing the recent serendipitous discovery of an x-ray burst of exactly the kind he proposed, and the insights into core collapse supernovae and GRBs that it provided.

  11. Stirling Colgate and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Lamb, Donald

    2014-10-01

    Even before the discovery of gamma-ray bursts (GRBs), Stirling Colgate proposed that bursts of x rays and gamma rays might be produced by a relativistic shock created in the supernova explosion of a massive star. We trace the scientific story of GRBs from their detection to the present, highlighting along the way Stirling's interest in them and his efforts to understand them. We summarize our current understanding that short, soft, repeating bursts are produced by magnetic neutron stars; short, hard bursts are produced by the mergers of neutron star-neutron star binaries; and long, hard bursts are produced by the core collapse of massive stars that have lost their hydrogen and helium envelopes. We then discuss some important open questions about GRBs and how they might be answered. We conclude by describing the recent serendipitous discovery of an x-ray burst of exactly the kind he proposed, and the insights into core collapse supernovae and GRBs that it provided.

  12. Gamma Ray Bursts: a 1983 Overview

    NASA Technical Reports Server (NTRS)

    Cline, T. L.

    1983-01-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect; energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all; burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective; finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  13. Gamma ray bursts: a 1983 overview

    SciTech Connect

    Cline, T.L.

    1983-10-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect. Energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all. Burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective. Finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  14. Ginga Gamma-Ray Burst Line Occurrence

    NASA Technical Reports Server (NTRS)

    Band, David

    1998-01-01

    The purpose of this project is the statistical evaluation of the occurrence of spectral lines in the gamma-ray burst spectra detected by the Ginga burst detector, and the comparison of the Ginga results to the BATSE observations. Two significant line features were detected in the Ginga bursts, but thus far none have been detected in the bursts BATSE detected. These line features may indicate the presence of strong magnetic fields in bursts, and therefore are important physical diagnostics of the conditions in the plasma which radiates the observed gamma-rays. The issue is whether there is a discrepancy between the Ginga and BATSE results; the potential discrepancy must be evaluated statistically. Even if BATSE line detections are announced, the statistical methodology we have developed can be used to estimate the rate at which different types of spectral features occur.

  15. The Gamma-Ray Burst Next Door

    NASA Technical Reports Server (NTRS)

    Wanjek, Christopher

    2003-01-01

    I hesitate to spawn a thousand bad sci-fi flicks, but here it goes: Scientists now say that some gamma-ray bursts, the most powerful explosions in the universe, originate in nearby galaxy clusters. If one were to occur nearby, it could wipe out life on Earth. Fortunately, the chances of mass extinction are slimmer than the Chicago Cubs meeting the Boston Red Sox in the World Series (. . . and the Red Sox winning). But a new analysis of over 1400 archived gamma-ray bursts reveals that about 100 bursts originated within 325 million light-years of Earth, and not billions of light-years away as previously thought. If so, there's no reason why a burst couldn't go off in our galaxy.

  16. The Gamma-Ray Burst Next Door

    NASA Technical Reports Server (NTRS)

    Wanjek, Christopher

    2003-01-01

    I hesitate to spawn a thousand bad sci-fi flicks, but here it goes: Scientists now say that some gamma-ray bursts, the most powerful explosions in the universe, originate in nearby galaxy clusters. If one were to occur nearby, it could wipe out life on Earth. Fortunately, the chances of mass extinction are slimmer than the Chicago Cubs meeting the Boston Red Sox in the World Series (. . . and the Red Sox winning). But a new analysis of over 1400 archived gamma-ray bursts reveals that about 100 bursts originated within 325 million light-years of Earth, and not billions of light-years away as previously thought. If so, there's no reason why a burst couldn't go off in our galaxy.

  17. Prompt Radio Emission from Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Gotthardt, Noelle

    2010-02-01

    Gamma-ray bursts have been observed, but these enigmatic objects are yet unexplained. These short duration events are undoubtedly due to high-energy events. Fading optical emission and even radio emission has been observed from such events, but prompt radio emission from these events would be very useful in pinning down the physics of the bursts, the nature of the progenitor object,and possibly the medium in which it occurs. If these phenomena occur at large redshifts, there is the possibility that the observations could probe the Epoch of Reionization, or the intergalactic medium. A number of models have been proposed to explain the gamma-ray bursts, ranging from compact object mergers, to maser-like coherent emission. These models are not well constrained by current observations. Prompt radio emission may be detected by a transient radio array. I will discuss a planned search for such signals by the Eight-meter-wavelength Transient Array (ETA). )

  18. Neutrino flux from observable Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Spada, M.; Guetta, D.; Waxman, E.

    2000-12-01

    We derive the flux and spectrum of neutrinos from Gamma Ray Bursts (GRBs), and the corresponding detection rate in a cubic-km neutrino detector, within the frame work of the Internal Shock Model. In this model, GRBs are produced by internal shocks in a highly relativistic wind, and high energy neutrinos result from photo-meson interactions of wind protons with gamma-ray photons. We show that the predicted neutrino flux is only weakly dependent on unknown wind parameters, due to the fact that observed GRB characteristics require these parameters to be strongly correlated. Thus, the predicted neutrino luminosity does not vary strongly from burst to burst. Several tens of events per year, correlated with GRBs, are expected to be detected in a cubic-km detector.

  19. THE FERMI GAMMA-RAY BURST MONITOR

    SciTech Connect

    Meegan, Charles; Lichti, Giselher; Bissaldi, Elisabetta; Diehl, Roland; Greiner, Jochen; Von Kienlin, Andreas; Steinle, Helmut; Bhat, P. N.; Briggs, Michael S.; Connaughton, Valerie; Paciesas, W. S.; Preece, Robert; Wilson, Robert B.; Fishman, Gerald; Kouveliotou, Chryssa; Van der Horst, Alexander J.; McBreen, Sheila

    2009-09-01

    The Gamma-Ray Burst Monitor (GBM) will significantly augment the science return from the Fermi Observatory in the study of gamma-ray bursts (GRBs). The primary objective of GBM is to extend the energy range over which bursts are observed downward from the energy range of the Large Area Telescope (LAT) on Fermi into the hard X-ray range where extensive previous data sets exist. A secondary objective is to compute burst locations onboard to allow re-orienting the spacecraft so that the LAT can observe delayed emission from bright bursts. GBM uses an array of 12 sodium iodide scintillators and two bismuth germanate scintillators to detect gamma rays from {approx}8 keV to {approx}40 MeV over the full unocculted sky. The onboard trigger threshold is {approx}0.7 photons cm{sup -2} s{sup -1} (50-300 keV, 1 s peak). GBM generates onboard triggers for {approx}250 GRBs per year.

  20. Do gamma-ray burst sources repeat?

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.; Hartmann, Dieter H.; Brainerd, J. J.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey; Kouveliotou, Chryssa; Fishman, Gerald; Blumenthal, George; Brock, Martin

    1995-01-01

    The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports (Quashnock and Lamb, 1993; Wang and Lingenfelter, 1993) of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al., 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic and the two-point angular correlation function. We find the data to be consistent with the hypothesis that burst sources do not repeat; however, a repeater fraction of up to about 20% of the observed bursts cannot be excluded.

  1. Short gamma-ray bursts: A review

    NASA Astrophysics Data System (ADS)

    D'Avanzo, P.

    2015-09-01

    Gamma-Ray Bursts (GRBs) are rapid, bright flashes of radiation peaking in the gamma-ray band occurring at an average rate of one event per day at cosmological distances. They are characterized by a collimated relativistic outflow pushing through the interstellar medium shining in gamma-rays powered by a central engine. This prompt phase is followed by a fading afterglow emission at longer wavelength, powered in part by the expanding outflow, and in part by continuous energy injection by the central engine. The observed evidences of supernovae associated to long GRBs (those with a duration of the gamma-ray emission > 2 s) brought to a general consensus on indicating the core collapse of massive stars as the progenitor of these events. Following the most accredited model, short GRBs (the events with a duration of the gamma-ray emission ≤ 2 s) originate from the coalescence of compact binary systems (two neutron stars or neutron star-black hole systems). This paper presents a review of the observational properties of short GRBs and shows how the study of these properties can be used as a tool to unveil their elusive progenitors and provide information on the nature of the central engine powering the observed emission. The increasing evidence for compact object binary progenitors makes short GRBs one of the most promising sources of gravitational waves for the forthcoming Advanced LIGO/Virgo experiments.

  2. Very high-energy gamma rays from gamma-ray bursts.

    PubMed

    Chadwick, Paula M

    2007-05-15

    Very high-energy (VHE) gamma-ray astronomy has undergone a transformation in the last few years, with telescopes of unprecedented sensitivity having greatly expanded the source catalogue. Such progress makes the detection of a gamma-ray burst at the highest energies much more likely than previously. This paper describes the facilities currently operating and their chances for detecting gamma-ray bursts, and reviews predictions for VHE gamma-ray emission from gamma-ray bursts. Results to date are summarized.

  3. Gamma ray bursts of black hole universe

    NASA Astrophysics Data System (ADS)

    Zhang, T. X.

    2015-07-01

    Slightly modifying the standard big bang theory, Zhang recently developed a new cosmological model called black hole universe, which has only a single postulate but is consistent with Mach's principle, governed by Einstein's general theory of relativity, and able to explain existing observations of the universe. In the previous studies, we have explained the origin, structure, evolution, expansion, cosmic microwave background radiation, quasar, and acceleration of black hole universe, which grew from a star-like black hole with several solar masses through a supermassive black hole with billions of solar masses to the present state with hundred billion-trillions of solar masses by accreting ambient matter and merging with other black holes. This study investigates gamma ray bursts of black hole universe and provides an alternative explanation for the energy and spectrum measurements of gamma ray bursts according to the black hole universe model. The results indicate that gamma ray bursts can be understood as emissions of dynamic star-like black holes. A black hole, when it accretes its star or merges with another black hole, becomes dynamic. A dynamic black hole has a broken event horizon and thus cannot hold the inside hot (or high-frequency) blackbody radiation, which flows or leaks out and produces a GRB. A star when it collapses into its core black hole produces a long GRB and releases the gravitational potential energy of the star as gamma rays. A black hole that merges with another black hole produces a short GRB and releases a part of their blackbody radiation as gamma rays. The amount of energy obtained from the emissions of dynamic star-like black holes are consistent with the measurements of energy from GRBs. The GRB energy spectra derived from this new emission mechanism are also consistent with the measurements.

  4. Cascade model of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Sturrock, P. A.; Harding, A. K.; Daugherty, J. K.

    1989-01-01

    If, in a neutron star magnetosphere, an electron is accelerated to an energy of 10 to the 11th or 12th power eV by an electric field parallel to the magnetic field, motion of the electron along the curved field line leads to a cascade of gamma rays and electron-positron pairs. This process is believed to occur in radio pulsars and gamma ray burst sources. Results are presented from numerical simulations of the radiation and photon annihilation pair production processes, using a computer code previously developed for the study of radio pulsars. A range of values of initial energy of a primary electron was considered along with initial injection position, and magnetic dipole moment of the neutron star. The resulting spectra was found to exhibit complex forms that are typically power law over a substantial range of photon energy, and typically include a dip in the spectrum near the electron gyro-frequency at the injection point. The results of a number of models are compared with data for the 5 Mar., 1979 gamma ray burst. A good fit was found to the gamma ray part of the spectrum, including the equivalent width of the annihilation line.

  5. Plasma Instabilities in Gamma-Ray Bursts

    SciTech Connect

    Tautz, Robert C.

    2008-12-24

    Magnetic fields are important in a variety of astrophysical scenarios, ranging from possible creation mechanisms of cosmological magnetic fields through relativistic jets such as that from Active Galactic Nuclei and gamma-ray bursts to local phenomena in the solar system. Here, the outstanding importance of plasma instabilities to astrophysics is illustrated by applying the so-called neutral point method to gamma-ray bursts (GRBs), which are assumed to have a homogeneous background magnetic field. It is shown how magnetic turbulence, which is a prerequisite for the creation of dissipation and, subsequently, radiation, is created by the highly relativistic particles in the GRB jet. Using the fact that different particle compositions lead to different instability conditions, conclusions can be drawn about the particle composition of the jet, showing that it is more likely of baryonic nature.

  6. Heterogeneity in Short Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Norris, Jay P.; Gehrels Neil; Scargle, Jeffrey D.

    2011-01-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample comprises 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales - durations, pulse structure widths, and peak intervals - for EE bursts are factors of approx 2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts - the anti-correlation of pulse intensity and width - continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/XRT. The median flux of the initial XRT detections for EE bursts (approx 6 X 10(exp -10) erg / sq cm/ s) is approx > 20 x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts (approx 60,000 s) is approx 30 x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into more dense environments than non-EE bursts, or that the sometimes-dominant EE component efficiently p()wers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  7. HETEROGENEITY IN SHORT GAMMA-RAY BURSTS

    SciTech Connect

    Norris, Jay P.; Gehrels, Neil

    2011-07-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample is comprised of 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales-durations, pulse structure widths, and peak intervals-for EE bursts are factors of {approx}2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts-the anti-correlation of pulse intensity and width-continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition, we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/X-Ray Telescope (XRT). The median flux of the initial XRT detections for EE bursts ({approx}6x10{sup -10} erg cm{sup -2} s{sup -1}) is {approx}>20x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts ({approx}60,000 s) is {approx}30x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into denser environments than non-EE bursts, or that the sometimes-dominant EE component efficiently powers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  8. The Cannonball Model of Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Dar, A.

    2004-06-01

    The cannonball model (CB) of gamma ray bursts (GRBs) is incredibly more successful than the standard blast-wave models (SM) of GRBs, which suffer from profound inadequacies and limited predictive power. Te CB model is falsifiable in its hypothesis and results. Its predictions are summarized in simple analytical expressions, derived, in fair approximations, from first principles. It provides a good description on a universal basis of the properties of long-duration GRBs and of their afterglows (AGs).

  9. Gamma-Ray Bursts: A Mystery Story

    NASA Technical Reports Server (NTRS)

    Parsons, Ann

    2007-01-01

    With the success of the Swift Gamma-Ray Burst Explorer currently in orbit, this is quite an exciting time in the history of Gamma Ray Bursts (GRBs). The study of GRBs is a modern astronomical mystery story that began over 30 years ago with the serendipitous discovery of these astronomical events by military satellites in the late 1960's. Until the launch of BATSE on the Compton Gamma-ray Observatory, astronomers had no clue whether GRBs originated at the edge of our solar system, in our own Milky Way Galaxy or incredibly far away near the edge of the observable Universe. Data from BATSE proved that GRBs are distributed isotropically on the sky and thus could not be the related to objects in the disk of our Galaxy. Given the intensity of the gamma-ray emission, an extragalactic origin would require an astounding amount of energy. Without sufficient data to decide the issue, a great debate continued about whether GRBs were located in the halo of our own galaxy or were at extragalactic - even cosmological distances. This debate continued until 1997 when the BeppoSAX mission discovered a fading X-ray afterglow signal in the same location as a GRB. This discovery enabled other telescopes, to observe afterglow emission at optical and radio wavelengths and prove that GRBs were at cosmological distances by measuring large redshifts in the optical spectra. Like BeppoSAX Swift, slews to new GRB locations to measure afterglow emission. In addition to improved GRB sensitivity, a significant advantage of Swift over BeppoSAX and other missions is its ability to slew very quickly, allowing x-ray and optical follow-up measurements to be made as early as a minute after the gamma-ray burst trigger rather than the previous 6-8 hour delay. Swift afterglow measurements along with follow-up ground-based observations, and theoretical work have allowed astronomers to identify two plausible scenarios for the creation of a GRB: either through core collapse of super massive stars or

  10. Gamma-Ray Bursts: A Mystery Story

    NASA Technical Reports Server (NTRS)

    Parsons, Ann

    2007-01-01

    With the success of the Swift Gamma-Ray Burst Explorer currently in orbit, this is quite an exciting time in the history of Gamma Ray Bursts (GRBs). The study of GRBs is a modern astronomical mystery story that began over 30 years ago with the serendipitous discovery of these astronomical events by military satellites in the late 1960's. Until the launch of BATSE on the Compton Gamma-ray Observatory, astronomers had no clue whether GRBs originated at the edge of our solar system, in our own Milky Way Galaxy or incredibly far away near the edge of the observable Universe. Data from BATSE proved that GRBs are distributed isotropically on the sky and thus could not be the related to objects in the disk of our Galaxy. Given the intensity of the gamma-ray emission, an extragalactic origin would require an astounding amount of energy. Without sufficient data to decide the issue, a great debate continued about whether GRBs were located in the halo of our own galaxy or were at extragalactic - even cosmological distances. This debate continued until 1997 when the BeppoSAX mission discovered a fading X-ray afterglow signal in the same location as a GRB. This discovery enabled other telescopes, to observe afterglow emission at optical and radio wavelengths and prove that GRBs were at cosmological distances by measuring large redshifts in the optical spectra. Like BeppoSAX Swift, slews to new GRB locations to measure afterglow emission. In addition to improved GRB sensitivity, a significant advantage of Swift over BeppoSAX and other missions is its ability to slew very quickly, allowing x-ray and optical follow-up measurements to be made as early as a minute after the gamma-ray burst trigger rather than the previous 6-8 hour delay. Swift afterglow measurements along with follow-up ground-based observations, and theoretical work have allowed astronomers to identify two plausible scenarios for the creation of a GRB: either through core collapse of super massive stars or

  11. RADIO FLARES FROM GAMMA-RAY BURSTS

    SciTech Connect

    Kopač, D.; Mundell, C. G.; Kobayashi, S.; Virgili, F. J.; Harrison, R.; Japelj, J.; Gomboc, A.; Guidorzi, C.; Melandri, A.

    2015-06-20

    We present predictions of centimeter and millimeter radio emission from reverse shocks (RSs) in the early afterglows of gamma-ray bursts (GRBs) with the goal of determining their detectability with current and future radio facilities. Using a range of GRB properties, such as peak optical brightness and time, isotropic equivalent gamma-ray energy, and redshift, we simulate radio light curves in a framework generalized for any circumburst medium structure and including a parameterization of the shell thickness regime that is more realistic than the simple assumption of thick- or thin-shell approximations. Building on earlier work by Mundell et al. and Melandri et al. in which the typical frequency of the RS was suggested to lie at radio rather than optical wavelengths at early times, we show that the brightest and most distinct RS radio signatures are detectable up to 0.1–1 day after the burst, emphasizing the need for rapid radio follow-up. Detection is easier for bursts with later optical peaks, high isotropic energies, lower circumburst medium densities, and at observing frequencies that are less prone to synchrotron self-absorption effects—typically above a few GHz. Given recent detections of polarized prompt gamma-ray and optical RS emission, we suggest that detection of polarized radio/millimeter emission will unambiguously confirm the presence of low-frequency RSs at early time.

  12. Physics of Gamma Ray Burst Sources

    NASA Technical Reports Server (NTRS)

    Meszaros, Peter

    2004-01-01

    During this grant period, the physics of gamma-ray bursts was investigated. A number of new results have emerged. The importance of pair formation in high compactness burst spectra may help explain x-ray flashes; a universal jet shape is a likely explanation for the distribution of jet break times; gravitational waves may be copiously produced both in short bursts from compact mergers and in long bursts arising from collapsars; x-ray iron lines are likely to be due to interaction with the stellar atmosphere of the progenitor; prompt optical flashes from reverse shocks will give diagnostics on the Lorentz factor and the environment; GeV and TeV emission from bursts may be expected in the external shock; etc. The group working with the PI included postdocs Dr. Bing Zhang (now assistant professor at University of Nevada); Dr. Shiho Kobayashi; graduate student Lijun Gou; collaborators Drs. Tim Kallman and Martin Rees. Meszaros shared with Rees and Dr. Bohan Paczynsky the AAS Rossi Prize in 2000 for their work on the theory of gamma ray bursts. The refereed publications and conference proceedings resulting from this research are summarized below. The PI gave a number of invited talks at major conferences, also listed.

  13. Physics of Gamma Ray Burst Sources

    NASA Technical Reports Server (NTRS)

    Meszaros, Peter

    2004-01-01

    During this grant period, the physics of gamma-ray bursts was investigated. A number of new results have emerged. The importance of pair formation in high compactness burst spectra may help explain x-ray flashes; a universal jet shape is a likely explanation for the distribution of jet break times; gravitational waves may be copiously produced both in short bursts from compact mergers and in long bursts arising from collapsars; x-ray iron lines are likely to be due to interaction with the stellar atmosphere of the progenitor; prompt optical flashes from reverse shocks will give diagnostics on the Lorentz factor and the environment; GeV and TeV emission from bursts may be expected in the external shock; etc. The group working with the PI included postdocs Dr. Bing Zhang (now assistant professor at University of Nevada); Dr. Shiho Kobayashi; graduate student Lijun Gou; collaborators Drs. Tim Kallman and Martin Rees. Meszaros shared with Rees and Dr. Bohan Paczynsky the AAS Rossi Prize in 2000 for their work on the theory of gamma ray bursts. The refereed publications and conference proceedings resulting from this research are summarized below. The PI gave a number of invited talks at major conferences, also listed.

  14. Gamma-Ray Bursts - A Cosmic Riddle

    NASA Astrophysics Data System (ADS)

    Woosley, S. E.

    1994-12-01

    A deep and abiding mystery is one of the greatest treasures nature has to offer to scientists and the public alike. Gamma-ray bursts have been observed for over 20 years. More than 2000 papers have been published about them and numerous theoretical models proposed, yet no one knows for sure what they are, where they come from, or even if they are a single class of phenomena. Isotropy and confinement (i.e., a deficiency of faint sources compared to that expected for an unbounded homogeneous sample), as exhibited in the BATSE observations from the Compton Gamma-Ray Observatory, have lead us to consider seriously only two sites - an extended Galactic halo populated by neutron stars, or else cosmologically distant sources. Models of both varieties will be reviewed. At the present time, both classes of models are given about equal credence, though ALL current models make troublesome assumptions requiring clarification. Halo models have received several boosts lately, including the realization that the mean velocity of pulsars is greater than previously thought, the certain localization of two out of three (and possibly all) soft gamma-ray repeaters to supernova remnants in our Galaxy and in the LMC, and calculations to show that under certain, albeit highly restrictive assumptions, the BATSE statistics can be satisfied by high velocity neutron stars ejected from the Galaxy. Several current halo oriented theories would like to relate the soft repeaters to the more common ``classical" bursts and claim that the former are an earlier evolutionary stage of the latter. If, on the other hand, the soft repeaters are a separate class, as the cosmologists would require, perhaps there are other classes as well. Amid all this theoretical speculation, the solution to the gamma-ray burst riddle will most likely come from further observation. Some prospects for future observations, especially with the High Energy Transient Experiment, will be briefly discussed.

  15. Distribution of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Diaz Rodriguez, Mariangelly; Smith, M.; Tešic, G.

    2014-01-01

    Gamma-Ray Bursts (GRBs) are known to be bright, irregular flashes of gamma rays that typically last just a few seconds, believed to be caused by stellar collapse or the merger of a pair of compact objects. Through previous work, it has been found that GRBs are distributed roughly uniformly over the entire sky, rather than being confined to the relatively narrow band of the Milky Way. Using the Python programming language, we generated a model of GRBs over cosmological distances, based on current empirical GRB distributions. The grbsim python module uses the acceptance-rejection Monte Carlo method to simulate the luminosity and redshift of a large population of GRBs, including cosmological effects such as dark energy and dark matter terms that modify the large-scale structure of space-time. The results of running grbsim are demonstrated to match the distribution of GRBs observed by the Burst Alert Telescope on NASA’s Swift satellite. The grbsim module will subsequently be used to simulate gamma ray and neutrino events for the Astrophysical Multimessenger Observatory Network.

  16. SuperAGILE and Gamma Ray Bursts

    SciTech Connect

    Pacciani, Luigi; Costa, Enrico; Del Monte, Ettore; Donnarumma, Immacolata; Evangelista, Yuri; Feroci, Marco; Frutti, Massimo; Lazzarotto, Francesco; Lapshov, Igor; Rubini, Alda; Soffitta, Paolo; Tavani, Marco; Barbiellini, Guido; Mastropietro, Marcello; Morelli, Ennio; Rapisarda, Massimo

    2006-05-19

    The solid-state hard X-ray imager of AGILE gamma-ray mission -- SuperAGILE -- has a six arcmin on-axis angular resolution in the 15-45 keV range, a field of view in excess of 1 steradian. The instrument is very light: 5 kg only. It is equipped with an on-board self triggering logic, image deconvolution, and it is able to transmit the coordinates of a GRB to the ground in real-time through the ORBCOMM constellation of satellites. Photon by photon Scientific Data are sent to the Malindi ground station at every contact. In this paper we review the performance of the SuperAGILE experiment (scheduled for a launch in the middle of 2006), after its first onground calibrations, and show the perspectives for Gamma Ray Bursts.

  17. The GAMCIT gamma ray burst detector

    NASA Technical Reports Server (NTRS)

    Mccall, Benjamin J.; Grunsfeld, John M.; Sobajic, Srdjan D.; Chang, Chinley Leonard; Krum, David M.; Ratner, Albert; Trittschuh, Jennifer E.

    1993-01-01

    The GAMCIT payload is a Get-Away-Special payload designed to search for high-energy gamma-ray bursts and any associated optical transients. This paper presents details on the design of the GAMCIT payload, in the areas of battery selection, power processing, electronics design, gamma-ray detection systems, and the optical imaging of the transients. The paper discusses the progress of the construction, testing, and specific design details of the payload. In addition, this paper discusses the unique challenges involved in bringing this payload to completion, as the project has been designed, constructed, and managed entirely by undergraduate students. Our experience will certainly be valuable to other student groups interested in taking on a challenging project such as a Get-Away-Special payload.

  18. Gamma-Ray Bursts and Cosmology

    NASA Technical Reports Server (NTRS)

    Norris, Jay P.

    2003-01-01

    The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities must be calibrated, and the luminosity function versus redshift must be measured or inferred. Several nascent relationships between gamma-ray temporal or spectral indicators and luminosity or total energy have been reported. These measures promise to further our understanding of GRBs once the connections between the luminosity indicators and GRB jets and emission mechanisms are better elucidated. The current distribution of 33 redshifts determined from host galaxies and afterglows peaks near z $\\sim$ 1, whereas for the full BATSE sample of long bursts, the lag-luminosity relation predicts a broad peak z $\\sim$ 1--4 with a tail to z $\\sim$ 20, in rough agreement with theoretical models based on star formation considerations. For some GRB subclasses and apparently related phenomena -- short bursts, long-lag bursts, and X-ray flashes -- the present information on their redshift distributions is sparse or entirely lacking, and progress is expected in Swift era when prompt alerts become numerous.

  19. A Gamma-Ray Burst Trigger Toolkit

    NASA Technical Reports Server (NTRS)

    Band, David L.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    The detection rate of a gamma-ray burst detector can be increased by using a count rate trigger with many accumulation times DELTAt and energy bands DELTAE Because a burst's peak flux varies when averaged over different DELTAt and DELTAE the nominal sensitivity (the numerical value of the peak flux) of a trigger system is less important than how much fainter a burst could be at the detection threshold as DELTAt and DELTAE are changed. The relative sensitivity of different triggers can be quantified by referencing the detection threshold back to the peak flux for a fiducial value of DELTAt and DELTA E. This mapping between peak flux values for different sets of DELTAt and DELTAE varies from burst to burst. Quantitative estimates of the burst detection rate for a given detector and trigger system can be based on the observed rate at a measured peak flux value in this fiducial trigger. Predictions of a proposed trigger's burst detection rate depend on the assumed burst population, and these predictions can be wildly in error for triggers that differ significantly from previous missions. I base the fiducial rate on the BATSE observations: 550 bursts per sky above a peak flux of 0.3 ph per square centimeter per second averaged over DELTAt=1.024 sec and DELTAE=50-300 keV. Using a sample of 100 burst lightcurves I find that triggering on any value of DELTAt that is a multiple of 0.064 sec decreases the average threshold peak flux on the 1.024 sec timescale by a factor of 0.6. Extending DELTAE to lower energies includes the large flux of the X-ray background, increasing the background count rate. Consequently a low energy DELTAE is advantageous only for very soft bursts. Whether a large fraction of the population of bright bursts is soft is disputed; the new population of X-ray Flashes is soft but relatively faint.

  20. Gamma ray burst outflows and afterglows

    NASA Astrophysics Data System (ADS)

    Morsony, Brian J.

    2008-08-01

    We carry out a theoretical investigation of jet propagation in Gamma Ray Bursts and examine the jitter radiation mechanism as a means of producing prompt and afterglow emission. We study the long-term evolution of relativistic jets in collapsars and examine the effects of viewing angle on the subsequent gamma ray bursts. Our simulations allow us to single out three phases in the jet evolution: a precursor phase in which relativistic material turbulently shed from the head of the jet first emerges from the star; a shocked jet phase where a fully shocked jet of material is emerging; and an unshocked jet phase where the jet consists of a free-streaming, unshocked core surrounded by a thin boundary layer of shocked jet material. We also carry out a series of simulations with central engines that vary on long time periods comparable to the breakout time of the jet, on short time periods (0.1s) much less than the breakout time, and finally that decay as a power law at late times. We conclude that rapid variability seen in prompt GRB emission, as well as shallow decays and flares seen in the X-ray afterglow, can be caused by central engine variability. Finally, we present a detailed computation of the jitter radiation spectrum, including self-absorption, for electrons inside Weibel-like shock- generated magnetic fields. We apply our results to the case of the prompt and afterglow emission of gamma-ray bursts. We conclude that jitter and synchrotron afterglows can be distinguished from each other with good quality observations. However, it is unlikely that the difference can explain the peculiar behavior of several recent observations, such as flat X-ray slopes and uncorrelated optical and X-ray behavior.

  1. 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.

  2. Gamma ray bursts from extragalactic sources

    NASA Technical Reports Server (NTRS)

    Hoyle, Fred; Burbidge, Geoffrey

    1992-01-01

    The properties of gamma ray bursts of classical type are found to be explicable in terms of high speed collisions between stars. A model is proposed in which the frequency of such collisions can be calculated. The model is then applied to the nuclei of galaxies in general on the basis that galaxies, or at least some fraction of them, originate in the expulsion of stars from creation centers. Evidence that low level activity of this kind is also taking place at the center of our own Galaxy is discussed. The implications for galactic evolution are discussed and a negative view of black holes is taken.

  3. THE ORTHOGONAL GAMMA-RAY BURST MODEL

    SciTech Connect

    Contopoulos, Ioannis; Pugliese, Daniela; Nathanail, Antonios

    2014-01-01

    We explore the analogy between a rotating magnetized black hole and an axisymmetric pulsar and derive the black hole's electromagnetic spindown after its formation in the core collapse of a supermassive star. The spindown shows two characteristic phases: an early Blandford-Znajek phase that lasts a few hundred seconds and a late pulsar-like afterglow phase that lasts much longer. During the first phase, the spindown luminosity decreases almost exponentially, whereas during the afterglow phase it decreases as t {sup –a} with 1 ≲ a ≲ 1.5. We associate our findings with long duration gamma-ray bursts and compare them with observations.

  4. Spectral evolution of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Band, D.; Matteson, J.; Ford, L.; Schaefer, B.; Teegarden, B.; Cline, T.; Paciesas, W.; Pendleton, G.; Fishman, G.; Meegan, C.

    1992-01-01

    BATSE's Spectral Detectors provide a series of high resolution spectra over the duration of a gamma-ray burst; fits to these spectra show the evolution of the continuum as the burst progresses. The burst continuum can usually be fit by the spectral form AE sup alpha exp(-E/kT) from around 25 keV to more than 3 MeV, with varying trends in the value and evolution of the spectral parameters. As a result of limited statistics for E greater than 1 - 2 MeV in the individual spectra, a high energy power law is not required. Only long duration strong bursts can be studied by fitting a series of spectra, and therefore our conclusions concern only this class of burst. The bursts we analyzed tend to be characterized by a hard-to-soft trend both for individual intensity spikes and for the burst as a whole: the hardness leads the count rate in spectra which resolve the temporal variations, while the hardness of successive spikes decreases. We also summarize the performance of the Spectral Detectors and the development of analysis tools to date.

  5. Gamma ray bursts: Current status of observations and theory

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    1990-01-01

    Gamma ray bursts display a wide range of temporal and spectral characteristics, but typically last several seconds and emit most of their energy in a low energy, gamma ray region. The burst sources appear to be isotropically distributed on the sky. Several lines of evidence suggest magnetic neutron stars as sources for bursts. A variety of energy sources and emission mechanisms are proposed.

  6. Environments of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Roming, Peter; Tobler, Jennifer

    2016-01-01

    The death of some of the most massive stars are manifest as long gamma-ray bursts (GRBs). Studying their light curves and spectra are uncovering some of the properties of the "central engine" that remains after the progenitor star collapses, as well as the environment in which they reside. Much of our current understanding comes from data obtained in the gamma-ray to X-ray. Despite this progress in the high-energy regime, our understanding of the soft-energy component (UV/optical) is lacking, particularly with regards to UV/optical flaring from the central engine and distinguishing between interstellar material and wind environments. Although these questions have been addressed for individual bursts, no systematic study in the UV/optical has been done due to the lack of a large homogenous sample. The Swift Ultra-Violet/Optical Telescope (UVOT) has observed more GRBs in the UV/optical than any other telescope. From these observations we have generated a homogenous UV/optical GRB afterglow catalog. From this catalog and coupled with archival Swift X-Ray Telescope (XRT) data, we examine the spectral evolution of GRBs in order to probe the circumburst environment and to test current progenitor models.

  7. Gamma-Ray Bursts: Characteristics and Prospects

    NASA Astrophysics Data System (ADS)

    Azzam, W. J.; Zitouni, H.; Guessoum, N.

    2017-06-01

    Gamma-ray bursts (GRBs) are the most powerful explosions in the universe. They have remained the object of intense research ever since their discovery was declassified in the early 1970s. Several space-borne missions have been dedicated to their study, including the Compton Gamma-Ray Burst Observatory (CGRO) in the 1990s and the current Swift and Fermi satellites. However, despite several decades of focused research, the precise mechanisms behind these enigmatic explosions have not been fully established. In the first part of this paper, we review what is currently known about GRBs. This includes: GRB light-curves and spectra; the different progenitor models, i.e., the "collapsar" and "merger" models; and the afterglow characteristics, including external shocks and the surrounding medium. In the second part of the paper, we present our work, which focuses on utilizing GRBs as cosmological probes. GRBs are ideal cosmological tools, because they have been observed to great distances (redshifts up to z = 9.4) and their radiation is unencumbered by any intervening dust. Although GRBs are not standard candles, the discovery of several energy and luminosity correlations, like the Amati relation which correlates the intrinsic spectral peak energy, Ep,i to the equivalent isotropic energy, Eiso , has ushered in a new era in which GRBs are used to investigate cosmological issues like the star formation rate and the value of the matter-density parameter, ΩM.

  8. The Chase to Capture Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2008-01-01

    Gamma-ray bursts are the most powerful explosions in the universe, thought to be the birth cries of black holes. It has taken 40 years of international cooperation and competition to begin to unravel the mystery of their origin. The most recent chapter in this field is being written by the SWIFT mission, a fast-response satellite with 3 power telescopes. An international team from countries all over the world participates in the chase to capture the fading light of bursts detected by SWIFT. This talk will discuss the challenges and excitement of building this space observatory. New results will be presented on our growing understanding of exploding stars and fiery mergers of orbiting stars.

  9. High-energy gamma rays from the intense 1993 January 31 gamma-ray burst

    NASA Technical Reports Server (NTRS)

    Sommer, M.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Fishman, G. J.; Harding, A. K.; Hartman, R. C.; Hunter, S. D.; Hurley, K.; Kanbach, G.

    1994-01-01

    The intense gamma-ray burst of 1993 January 31 was detected by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Observatory. Sixteen gamma rays above 30 MeV were imaged in the telescope when only 0.04 gamma rays were expected by chance. Two of these gamma rays have energies of approximately 1 GeV, and the five bin spectrum of the 16 events is fitted by a power law of photon spectral index -2.0 +/- 0.4. The high-energy emission extends for at least 25 s. The most probable direction for this burst is determined from the directions of the 16 gamma rays observed by Egret and also by requiring the position to lie on annulus derived by the Interplanetary Network.

  10. The Most Remote Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

    2000-10-01

    ESO Telescopes Observe "Lightning" in the Young Universe Summary Observations with telescopes at the ESO La Silla and Paranal observatories (Chile) have enabled an international team of astronomers [1] to measure the distance of a "gamma-ray burst", an extremely violent, cosmic explosion of still unknown physical origin. It turns out to be the most remote gamma-ray burst ever observed . The exceedingly powerful flash of light from this event was emitted when the Universe was very young, less than about 1,500 million years old, or only 10% of its present age. Travelling with the speed of light (300,000 km/sec) during 11,000 million years or more, the signal finally reached the Earth on January 31, 2000. The brightness of the exploding object was enormous, at least 1,000,000,000,000 times that of our Sun, or thousands of times that of the explosion of a single, heavy star (a "supernova"). The ESO Very Large Telescope (VLT) was also involved in trail-blazing observations of another gamma-ray burst in May 1999, cf. ESO PR 08/99. PR Photo 28a/00 : Sky field near GRB 000131 . PR Photo 28b/00 : The fading optical counterpart of GRB 000131 . PR Photo 28c/00 : VLT spectrum of GRB 000131 . What are Gamma-Ray Bursts? One of the currently most active fields of astrophysics is the study of the mysterious events known as "gamma-ray bursts" . They were first detected in the late 1960's by instruments on orbiting satellites. These short flashes of energetic gamma-rays last from less than a second to several minutes. Despite much effort, it is only within the last few years that it has become possible to locate the sites of some of these events (e.g. with the Beppo-Sax satellite ). Since the beginning of 1997, astronomers have identified about twenty optical sources in the sky that are associated with gamma-ray bursts. They have been found to be situated at extremely large (i.e., "cosmological") distances. This implies that the energy release during a gamma-ray burst within a few

  11. Gamma-Ray Burst Class Properties

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Haglin, David J.; Pendleton, Geoffrey N.; Mallozzi, Robert S.; Meegan, Charles A.; Roiger, Richard J.

    2000-01-01

    Guided by the supervised pattern recognition algorithm C4.5 developed by Quinlan in 1986, we examine the three gamma-ray burst classes identified by Mukherjee et al. in 1998. C4.5 provides strong statistical support for this classification. However, with C4.5 and our knowledge of the Burst and Transient Source Experiment (BATSE) instrument, we demonstrate that class 3 (intermediate fluence, intermediate duration, soft) does not have to be a distinct source population: statistical/systematic errors in measuring burst attributes combined with the well-known hardness/intensity correlation can cause low peak flux class 1 (high fluence, long, intermediate hardness) bursts to take on class 3 characteristics naturally. Based on our hypothesis that the third class is not a distinct one, we provide rules so that future events can be placed in either class 1 or class 2 (low fluence, short, hard). We find that the two classes are relatively distinct on the basis of Band's work in 1993 on spectral parameters alpha, beta, and E (sub peak) alone. Although this does not indicate a better basis for classification, it does suggest that different physical conditions exist for class 1 and class 2 bursts. In the process of studying burst class characteristics, we identify a new bias affecting burst fluence and duration measurements. Using a simple model of how burst duration can be underestimated, we show how this fluence duration bias can affect BATSE measurements and demonstrate the type of effect it can have on the BATSE fluence versus peak flux diagram.

  12. The Swift Gamma Ray Burst Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Chincarini, G.; Giommi, P.; Mason, K. O.; Nousek, J. A.; Wells, A. A.; White, N. E.; Barthelmy, S. D.; Burrows, D. N.; Cominsky, L. R.

    2004-01-01

    The Swift mission: scheduled for launch in early 2004: is a multiwavelength observatory for gamma-ray burst (GRB) astronomy. It is the first-of-its-kind autonomous rapid-slewing satellite for transient astronomy and pioneers the way for future rapid-reaction and multiwavelength missions. It will be far more powerful than any previous GRB mission, observing more than 100 bursts per year and performing detailed X-ray and UV/optical afterglow observations spanning timescales from 1 minute to several days after the burst. The objectives are to: 1) determine the origin of GFU3s; 2) classify GRBs and search for new types; 3) study the interaction of the ultra-relativistic outflows of GRBs with their surrounding medium; and 4) use GRBs to study the early universe out to z greater than 10. The mission is being developed by a NASA-led international collaboration. It will carry three instruments: a new-generation wide-field gamma-ray (15-150 keV) detector that will detect bursts, calculate 1-4 arcmin positions: and trigger autonomous spacecraft slews; a narrow-field X-ray telescope that will give 5 arcsec positions and perform spectroscopy in the 0.2 to 10 keV band; and a narrow-field UV/optical telescope that will operate in the 170-600 nm band and provide 0.3 arcsec positions and optical finding charts. Redshift determinations will be made for most bursts. In addition to the primary GRB science, the mission will perform a hard X-ray survey to a sensitivity of approx. 1 mCrab (approx. 2 x l0(exp -11) erg/sq cm s in the 15-150 keV band), more than an order of magnitude better than HEAO A-4. A flexible data and operations system will allow rapid follow-up observations of all types of high-energy transients. with rapid data downlink and uplink available through the NASA TDRSS system. Swift transient data will be rapidly distributed to the astronomical community and all interested observers are encouraged to participate in follow-up measurements. A Guest Investigator program

  13. Iron K Lines from Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Kallman, T. R.; Meszaros, P.; Rees, M. J.

    2003-01-01

    We present models for reprocessing of an intense flux of X-rays and gamma rays expected in the vicinity of gamma ray burst sources. We consider the transfer and reprocessing of the energetic photons into observable features in the X-ray band, notably the K lines of iron. Our models are based on the assumption that the gas is sufficiently dense to allow the microphysical processes to be in a steady state, thus allowing efficient line emission with modest reprocessing mass and elemental abundances ranging from solar to moderately enriched. We show that the reprocessing is enhanced by down-Comptonization of photons whose energy would otherwise be too high to absorb on iron, and that pair production can have an effect on enhancing the line production. Both "distant" reprocessors such as supernova or wind remnants and "nearby" reprocessors such as outer stellar envelopes can reproduce the observed line fluxes with Fe abundances 30-100 times above solar, depending on the incidence angle. The high incidence angles required arise naturally only in nearby models, which for plausible values can reach Fe line to continuum ratios close to the reported values.

  14. Solving the Mystery of Short Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    Gamma-ray bursts are among the most fascinating occurrences in the cosmos. Until this year, the origin of short gamma-ray bursts was a complete mystery. A new NASA satellite named Swift has now captured the first images of these events and found that they are caused by tremendous explosions in the distant universe.

  15. Optical Afterglows of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Pian, Elena

    2007-10-01

    The advent of the Swift mission for Gamma-Ray Bursts (GRBs) in late 2004 has more than doubled the existing sample of detected optical counterparts. The rapid dissemination of the accurate BAT and XRT localizations has allowed ground-based telescopes, especially the automatic ones, to slew timely to the GRB positions and to scan them efficiently in search of an afterglow. For about 25% of the Swift GRBs, the onboard UVOT instrument has also provided an early counterpart detection in the optical, and occasionally in the near-UV. There are now about 200 detected GRB optical afterglows, of which nearly 100 have a redshift measurement. I will review here some of the highlights in this field during the Swift era, with particular emphasis on the early (minutes to hours after explosion) optical light curves, on the afterglows of short GRBs, and on the supernova-GRB connection.

  16. Gamma ray bursts and their afterglows

    NASA Astrophysics Data System (ADS)

    Nicuesa Guelbenzu, A.

    2017-03-01

    Gamma-Ray Bursts (GRBs) were among the greatest mysteries in modern astrophysics. They were first observed 50 years ago but it took three decades before optical counterparts could be found and the underlying physical phenomena studied in detail. GRB research represents currently one of the most rapidly growing areas in extragalactic astronomy. This is due in large part to the numerous connections that GRBs have with other disciplines like cosmology, supernovae, stellar evolution, nuclear physics, astroparticle and gravitational wave astronomy. Therefore, their study is of great importance to understand various astrophysical phenomena such as the formation of the first stars, the chemical evolution and the expansion of the Universe. Since gamma radiation can travel along cosmological distances without being affected by any possible intervening absorption, GRBs can be detected from the most distant universe, reaching redshifts up to z = 10 or more.

  17. Radio Afterglows of Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Resmi, Lekshmi

    2017-09-01

    This review focuses on the physics of Gamma Ray Bursts probed through their radio afterglow emission. Even though radio band is the least explored of the afterglow spectrum, it has played an important role in the progress of GRB physics, specifically in confirming the hypothesized relativistic effects. Currently radio astronomy is in the beginning of a revolution. The high sensitive Square Kilometer Array (SKA) is being planned, its precursors and pathfinders are about to be operational, and several existing instruments are undergoing upgradation. Thus, the afterglow results from detection statistics and follow up programs are expected to improve in the coming years. We list a few avenues unique to radio band which if explored to full potential have the promise to greatly contribute to the future of GRB physics.

  18. The supernova-gamma-ray burst-jet connection.

    PubMed

    Hjorth, Jens

    2013-06-13

    The observed association between supernovae and gamma-ray bursts represents a cornerstone in our understanding of the nature of gamma-ray bursts. The collapsar model provides a theoretical framework for this connection. A key element is the launch of a bipolar jet (seen as a gamma-ray burst). The resulting hot cocoon disrupts the star, whereas the (56)Ni produced gives rise to radioactive heating of the ejecta, seen as a supernova. In this discussion paper, I summarize the observational status of the supernova-gamma-ray burst connection in the context of the 'engine' picture of jet-driven supernovae and highlight SN 2012bz/GRB 120422A--with its luminous supernova but intermediate high-energy luminosity--as a possible transition object between low-luminosity and jet gamma-ray bursts. The jet channel for supernova explosions may provide new insights into supernova explosions in general.

  19. Gamma-Ray Burst Counterparts: Optical Data

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.; Cline, Thomas L.; Hurley, Kevin C.; Laros, John G.

    1998-10-01

    The surest solution of the gamma-ray burst (GRB) mystery is to find an unambiguous low-energy quiescent counterpart. To this end, we have intensively searched within the smallest GRB error boxes for any counterpart candidates. This paper reports on 255 hr of exposure with ground-based telescopes since 1981. We report our results in the U, B, V, R. I, J, H, and K bands. We find the usual array of mildly unusual sources in the boxes, but none is sufficiently unusual to suggest a causal connection. We find that the smallest boxes are empty to fairly deep magnitudes. This fact can be of significance since virtually all cosmological models place bright bursters inside normal host galaxies at moderate distances. To allow for quantitative evaluation of the predictions of these models, we have compiled a list of limits on the brighest galaxy inside each of the 26 regions in various bands. This list was compiled from our own results as well as from the published literature. The limits on host galaxy luminosities from these data are substantially more restrictive than the limits from recent optical transients because the bursts we report on are much brighter than the bursts with optical transients.

  20. Bulk relativistic motion in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Krolik, Julian H.; Pier, Edward A.

    1992-01-01

    It is shown here that any model for gamma-ray bursts in which the gamma-rays in the source are isotropic in a frame moving relativistically with respect to external observers has several advantageous traits: hard photons can escape more easily, the radiated energy per burst is reduced, and stellar back-heating is virtually eliminated. In addition, several other features of gamma-ray burst phenomenology must be reinterpreted: the burst source density, or alternatively, the recurrence time per source, is altered, and the physical interpretation of spectral features may also be substantially changed.

  1. Energy sources in gamma-ray burst models

    NASA Technical Reports Server (NTRS)

    Taam, Ronald E.

    1987-01-01

    The current status of energy sources in models of gamma-ray bursts is examined. Special emphasis is placed on the thermonuclear flash model which has been the most developed model to date. Although there is no generally accepted model, if the site for the gamma-ray burst is on a strongly magnetized neutron star, the thermonuclear model can qualitatively explain the energetics of some, but probably not all burst events. The critical issues that may differentiate between the possible sources of energy for gamma-ray bursts are listed and briefly discussed.

  2. Thermonuclear model for. gamma. -ray bursts

    SciTech Connect

    Woosley, S.E.

    1981-08-26

    The evolution of magnetized neutron stars with field strengths of approx. 10/sup 12/ gauss that are accreting mass onto kilometer-sized polar regions at a rate of approx. /sup 13/ M/sub 0/yr/sup -1/ is examined. Based on the results of one-dimensional calculations, one finds that stable hydrogen burning, mediated by the hot CNO-cycle, will lead to a critical helium mass in the range 10/sup 20/ to 10/sup 22/ g km/sup -2/. Owing to the extreme degeneracy of the electron gas providing pressure support, helium burning occurs as a violent thermonuclear runaway which may propagate either as a convective deflagration (Type I burst) or as a detonation wave (Type II burst). Complete combustion of helium into /sup 56/Ni releases from 10/sup 38/ to 10/sup 40/ erg km/sup -2/ and pushes hot plasma with ..beta.. > 1 above the surface of the neutron star. Rapid expansion of the plasma channels a substantial fraction of the explosion energy into magnetic field stress. Spectral properties are expected to be complex with emission from both thermal and non-thermal processes. The hard ..gamma..-outburst of several seconds softens as the event proceeds and is followed by a period, typically of several minutes duration, of softer x-ray emission as the subsurface ashes of the thermonuclear explosion cool. In this model, most ..gamma..-ray bursts currently being observed are located at a distance of several hundred parsecs and should recur on a timescale of months to centuries with convective deflagrations (Type I bursts) being the more common variety. An explanation for Jacobson-like transients is also offered.

  3. Gamma-Ray Bursts: Pulses and Populations

    NASA Astrophysics Data System (ADS)

    Loredo, Thomas J.; Hakkila, J. E.; Broadbent, M.; Wasserman, I. M.; Wolpert, R. L.

    2013-04-01

    We describe ongoing work on two projects that are enabling more thorough and accurate use of archival BATSE data for elucidating the nature of GRB sources; the methods and tools we are developing will also be valuable for analyzing data from other missions. The first project addresses modeling the spectro-temporal behavior of prompt gamma ray emission from GRBs by modeling gamma ray count and event data with a population of pulses, with the population drawn from one or more families of single-pulse kernels. Our approach is built on a multilevel nonparametric probabilistic framework we have dubbed "Bayesian droplets," and offers several important advances over previous pulse decomposition approaches: (1) It works in the pulse-confusion regime, quantifying uncertainty in the number, locations, and shapes of pulses, even when there is strong overlap. (2) It can self-consistently model pulse behavior across multiple spectral bands. (3) It readily handles a variety of spatio-temporal kernel shapes. (4) It reifies the idea of a burst as a population of pulses, enabling explicit modeling and estimation of the pulse population distribution. We describe the framework and present analyses of prototypical simple and complex GRB light curves. The second project aims to enable accurate demographic modeling of GRBs using the BATSE catalog. We present new calculations of the BATSE sky exposure, encompassing the full duration of the BATSE catalog for the first time, with many improvements over the currently available exposure map. A similar calculation of the detection efficiency is in progress. We also describe public Python software enabling access and accurate modeling of BATSE GRB data. The software enables demographic studies (e.g., modeling log N - log S distributions) with accurate accounting of both selection effects and measurement errors. It also enables spectro-temporal modeling of detailed data from individual GRBs. These projects are supported by NASA through the AISR

  4. Gamma-ray bursts and related phenomena.

    NASA Astrophysics Data System (ADS)

    Piran, T.

    1999-01-01

    Gamma-ray bursts (GRBs) have puzzled astronomers since their accidental discovery in the 1960s. The BATSE detector on the Compton-GRO satellite has been detecting one burst per day for the last six years. Its findings have revolutionized our ideas about the nature of these objects. They have shown that GRBs are at cosmological distances. This idea was accepted with difficulties at first. However, the recent discovery of an X-ray afterglow by the Italian/Dutch satellite BeppoSAX led to a detection of high red-shift absorption lines in the optical afterglow of GRB 970508 and to a confirmation of its cosmological origin. The simplest and practically inevitable interpretation of these observations is that GRBs result from the conversion of the kinetic energy of ultra-relativistic particles flux to radiation in an optically thin region. Recent studies suggest the "internal-external" model: internal shocks that take place within the relativistic flow produce the GRB while the subsequent interaction of the flow with the external medium produces the afterglow. The "inner engine" that produces the flow is, however, hidden from direct observations. The author reviews this model with a specific emphasis on its implications to underground physics.

  5. Population III Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Toma, K.; Sakamoto, T.; Mészáros, P.

    Population III stars are theoretically expected to be prominent around redshifts z ˜ 20, consisting of mainly very massive stars (VMSs) with M_* ∼ 100;M_⊙, but 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_iso ∼ 1057;erg over a cosmological-rest-frame duration of t_d ∼ 104;s, depending on the progenitor mass. The detection of a burst with such a high total energy and a long duration would be a strong evidence for a VMS progenitor. We calculate the prompt emission and afterglow spectra of such Pop. III GRBs based on the standard models, and show that they will be detectable with the Swift BAT/XRT and Fermi LAT instruments. We also show that the late-time radio afterglows of Pop. III GRBs for typical parameters, despite the large distances, can be very bright: ≃ 140;mJy at 1;GHz, which may lead to a constraint on the Pop. III GRB rate from the current radio survey data, and ≃ 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.

  6. Gamma-Ray Bursts: Should cosmologists care?

    NASA Astrophysics Data System (ADS)

    Laros, J. G.

    1996-03-01

    Gamma-Ray Burst (GRB) locations are distributed isotropically on the sky, but the intensity distribution of the bursts seems clearly incompatible with spatial homogeneity. Of the scenarios that attempt to provide an explanation, there are two that enjoy current popularity: (1) GRBs are produced by high-velocity neutron stars that have formed an extended (˜100 kpc) spherical halo or “corona” around our galaxy. (2) The bursters are at cosmological distances, with redshifts near unity for the weaker events. The major evidence used to argue for or against each of these scenarios remains inconclusive. Assuming, not unreasonably, that the cosmological scenario is correct, one can discuss the advantages and disadvantages of studying GRBs as opposed to other objects at moderate redshift. We find that the advantages of GRBs-high intensity, penetrating radiation, rapid variability, and no expected source evolution-are offset by observational difficulties pertaining to the extraction of cosmological information from GRB data. If the cosmological scenario proves to be correct and if the observational difficulties are overcome, then cosmologists certainly should care.

  7. More Gamma-ray Bursts from the Fermi Gamma-ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Briggs, Michael; Fermi GBM Team Team

    2017-01-01

    The Fermi Gamma-ray Burst Monitor (GBM) Team has developed an offline search for weak gamma-ray bursts which were not already detected in-orbit as ``triggers''. This search is ``untargeted'', searching all of the GBM data without guidance from other observations. The initial version of the search has been operational from January 2016, finding several likely short GRBs per month that are posted to a webpage. The GBM individual photon data are binned to various timescales, a background model is created and the binned data are searched for significant signals above the background that are coincident in two or more detectors. The current search has a latency of several days because several steps require manual intervention. An improved version will be fully automatic so that the latency in detecting candidates will be dominated by the few hours delay in receiving the data. The new version of the search will also include additional detection algorithms to increase the GRB detection rate and will also detect some long GRBs. We will report the candidates via the Gamma-ray Coordinates Network (GCN). These prompt GRB detections and localization should aid multi-messenger observations, in some cases refining localizations on timescales useful for followup observations.

  8. Gamma ray bursts: Current status of observations and theory

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    1990-01-01

    Gamma-ray bursts display a wide range of temporal and spectral characteristics, but typically last several seconds and emit most of their energy in the low-energy gamma-ray region. The burst sources appear to be isotropically distributed on the sky. Several lines of evidence suggest magnetic neutron stars as sources for bursts. A variety of energy sources and emission mechanisms were proposed.

  9. An Integrated Universal Collapsar Gamma-ray Burst Model

    SciTech Connect

    Salmonson, J D

    2004-01-21

    Starting with two assumptions: (1) gamma-ray bursts originate from stellar death phenomena or so called ''collapsars'' and (2) that these bursts are quasi-universal, whereby the majority of the observed variation is due to our perspective of the jet, an integrated gamma-ray burst model is proposed. It is found that several of the key correlations in the data can be naturally explained with this simple picture and another possible correlation is predicted.

  10. Compton-dragged Gamma-Ray Bursts Associated with Supernovae.

    PubMed

    Lazzati; Ghisellini; Celotti; Rees

    2000-01-20

    It is proposed that the gamma-ray photons that characterize the prompt emission of gamma-ray bursts are produced through the Compton-drag process, which is caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with supernovae, then the exploding star can provide enough soft photons for radiative drag to be effective. This model accounts for the basic properties of gamma-ray bursts, i.e., the overall energetics, the peak frequency of the spectrum, and the fast variability, with an efficiency that can exceed 50%. In this scenario, there is no need for particle acceleration in relativistic collisionless shocks. Furthermore, although the Poynting flux may be important in accelerating the outflow, no magnetic field is required in the gamma-ray production. The drag also naturally limits the relativistic expansion of the fireball to Gamma less, similar104.

  11. Cannonballs in the context of gamma ray bursts. Formation sites?

    NASA Astrophysics Data System (ADS)

    Staff, J. E.; Fendt, C.; Ouyed, R.

    2006-05-01

    We investigate possible formation sites of the cannonballs (in the gamma ray bursts context) by calculating their physical parameters, such as density, magnetic field, and temperature close to the origin. Our results favor scenarios where the cannonballs form as instabilities (knots) within magnetized jets from hyperaccreting disks. These instabilities would most likely set in beyond the light cylinder where flow velocity with Lorentz factors as high as 2000 can be achieved. The cannonball model for gamma ray bursts requires that cannonballs form inside core-collapse supernovae. Our findings challenge the cannonball model of gamma ray bursts, unless hyperaccreting disks and the corresponding jets are common occurrences in core-collapse SNe.

  12. The first BATSE gamma-ray burst catalog

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Brock, Martin N.; Horack, John M.; Kouveliotou, Chryssa; Howard, Sethanne; Paciesas, William S.; Briggs, Michael S.; Pendleton, Geoffrey N.

    1994-01-01

    The Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory detected 260 cosmic gamma-ray bursts during the period 19 Apr 1991 to 5 Mar 1992. This paper presents the occurrence times, locations, peak count rates, peak fluxes, fluences, durations, and plots of time histories for these bursts. The angular distribution is consistent with isotropy. The intensity distribution shows a deficit in the number of weak bursts, which is not consistent with a homogeneous distribution of burst sources in Euclidean space. The duration distribution shows evidence for a separate class of bursts with durations less than about 2 seconds.

  13. Gamma-Ray Bursts in the Swift Era

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Ramirez-Ruiz, E.; Fox, D. B.

    2010-01-01

    With its rapid-response capability and multiwavelength complement of instruments, the Swift satellite has transformed our physical understanding of gamma-ray bursts. Providing high-quality observations of hundreds of bursts, and facilitating a wide range of follow-up observations within seconds of each event, Swift has revealed an unforeseen richness in observed burst properties, shed light on the nature of short-duration bursts, and helped realize the promise of gamma-ray bursts as probes of the processes and environments of star formation out to the earliest cosmic epochs. These advances have opened new perspectives on the nature and properties of burst central engines, interactions with the burst environment from microparsec to gigaparsec scales, and the possibilities for non-photonic signatures. Our understanding of these extreme cosmic sources has thus advanced substantially; yet more than forty years after their discovery, gamma-ray bursts continue to present major challenges on both observational and theoretical fronts.

  14. Gamma ray bursts from superconducting cosmic strings

    NASA Astrophysics Data System (ADS)

    Berezinsky, V.; Hnatyk, B.; Vilenkin, A.

    2001-08-01

    Cusps of superconducting strings can serve as GRB engines. A powerful beamed pulse of electromagnetic radiation from a cusp produces a jet of accelerated particles, whose propagation is terminated by the shock responsible for GRB. A single free parameter, the string scale of symmetry breaking η~1014 GeV, together with reasonable assumptions about the magnitude of cosmic magnetic fields and the fraction of volume that they occupy, explains the GRB rate, duration, and fluence, as well as the observed ranges of these quantities. The wiggles on the string can drive the short-time structures of GRB. This model predicts that GRBs are accompanied by strong bursts of gravitational radiation which should be detectable by LIGO, VIRGO, and LISA detectors. Another prediction is the diffuse x- and gamma-ray radiation at 8 MeV-100 GeV with a spectrum and flux comparable to the observed. The weakness of the model is the prediction of too low a rate of GRBs from galaxies, as compared with observations. This suggests that either the capture rate of string loops by galaxies is underestimated in our model or that GRBs from cusps are responsible for only a subset of the observed GRBs not associated with galaxies.

  15. Supernovae, hypernovae and gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Dar, Arnon

    2001-05-01

    Recent observations suggest that gamma ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in core collapse supernova explosions (SNe). The result of the event, probably, is not just a compact object plus a spherical ejecta: within a day, a fraction of the parent star falls back to produce a thick accretion disk around the compact object. Instabilities in the disk induce a sudden collapse with ejection of jets of highly relativistic ``cannonballs'' of plasma in opposite directions, similar to those ejected by microquasars. The jet of cannonballs exit the supernova shell/ejecta reheated by their collision with it, emitting highly forward-collimated radiation which is Doppler shifted to γ-ray energy. Each cannonball corresponds to an individual pulse in a GRB. They decelerate by sweeping up the ionized interstellar matter in front of them, part of which is accelerated to cosmic-ray energies and emits synchrotron radiation: the afterglow. The Cannonball Model cannot predict the timing sequence of these pulses, but it fares very well in describing the total energy, energy spectrum, and time-dependence of the individual γ-ray pulses and afterglows. It also predicts that GRB pulses are accompanied by detectable short pulses of TeV neutrinos and sub TeV γ-rays, that are much more energetic and begin and peak a little earlier. .

  16. Neutrino astronomy and gamma-ray bursts.

    PubMed

    Waxman, Eli

    2007-05-15

    The construction of large-volume detectors of high energy, greater than 1TeV, neutrinos is mainly driven by the search for extragalactic neutrino sources. The existence of such sources is implied by the observations of ultra-high-energy, greater than or equal to 1019eV, cosmic rays, the origin of which is a mystery. In this lecture, I briefly discuss the expected extragalactic neutrino signal and the current state of the experimental efforts. Neutrino emission from gamma-ray bursts (GRBs), which are probably sources of both high-energy protons and neutrinos, is discussed in some detail. The detection of the predicted GRB neutrino signal, which may become possible in the coming few years, will allow one to identify the sources of ultra-high-energy cosmic rays and to resolve open questions related to the underlying physics of GRB models. Moreover, detection of GRB neutrinos will allow one to test for neutrino properties (e.g. flavour oscillations and coupling to gravity) with an accuracy many orders of magnitude better than is currently possible.

  17. Gamma Ray Bursts and recent Swift Results .

    NASA Astrophysics Data System (ADS)

    Chincarini, G.

    Due to the large activity we had during these last months with the Swift satellite I started the writing of the presentation I gave at the SAIt Catania meeting only in the middle of September. The Swift satellite, however, never rested. Since then and in addition to the results I showed at the meeting in relation to the early and steep light curves observed with the XRT telescope in the 0.2 - 10 keV band, we had fundamental discoveries among which the detection and localization of short bursts and the detection of the largest redshift ever. It obviously would be improper to discuss here the most recent results but it would also be silly in such a fast evolving topics where the day by day observations show excellent results and the observer is far ahead of the theoretician, to write an article that, from the observational point of view, would be completely obsolete. The best approach here seems to be a brief description of what was presented during the meeting briefly mentioning also some of the most recent results. We remind the reader, however, that a copious literature written, and in preparation, exists so that we urge the reader to refer to the specialized articles. This brief article will touch on the basic characteristics of the Gamma Ray Bursts (GRBs) in the Introduction (section 1) and illustrate the basic characteristics of the Swift mission in section 2. Preliminary science results will be discussed in section 3 and finally we will mention one, among many, of the main goal we plan to achieve in Cosmology via the observations of very distant GRBs.

  18. Gamma-ray burst theory: Back to the drawing board

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    1994-01-01

    Gamma-ray bursts have always been intriguing sources to study in terms of particle acceleration, but not since their discovery two decades ago has the theory of these objects been in such turmoil. Prior to the launch of Compton Gamma-Ray Observatory and observations by Burst and Transient Source Experiment (BATSE), there was strong evidence pointing to magnetized Galactic neutron stars as the sources of gamma-ray bursts. However, since BATSE the observational picture has changed dramatically, requiring much more distant and possibly cosmological sources. I review the history of gamma-ray burst theory from the era of growing consensus for nearby neutron stars to the recent explosion of halo and cosmological models and the impact of the present confusion on the particle acceleration problem.

  19. Can Gamma Ray Bursts be Detected Using Infrasound

    NASA Astrophysics Data System (ADS)

    Palmer, Jahi; McGruder, C.; Hetzer, C.

    2010-01-01

    CAN GAMMA RAY BURST BE DETECTED USING INFRASOUND Infrasound has been used to detect sonic disturbances in earth's atmosphere caused by terrestrial events such as earthquakes and lightning. It may be possible to detect celestial events such as Gamma Ray Bursts (GRB's) through this method. We have searched for GRB's which are known to have caused ionospheric disturbances in infrasonic data. None of the selected GRB's were found to be associated with infrasonic disturbances.

  20. MIRAX sensitivity for Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Sacahui, J. R.; Penacchioni, A. V.; Braga, J.; Castro, M. A.; D'Amico, F.

    2016-03-01

    In this work we present the detection capability of the MIRAX (Monitor e Imageador de RAios-X) experiment for Gamma-Ray Bursts (GRBs). MIRAX is an X-ray astronomy mission designed to perform a wide band hard X-ray (10-200 keV) survey of the sky, especially in the Galactic plane. With a total detection area of 169 cm2, large field of view (FoV, 20 ° × 20 °), angular resolution of 1°45‧ and good spectral and time resolution (∼8% at 60 keV, 10 μs), MIRAX will be optimized for the detection and study of transient sources, such as accreting neutron stars (NS), black holes (BH), Active Galactic Nuclei (AGNs), and both short and long GRBs. This is especially important because MIRAX is expected to operate in an epoch when probably no other hard X-ray wide-field imager will be active. We have performed detailed simulations of MIRAX GRB observations using the GEANT4 package, including the background spectrum and images of GRB sources in order to provide accurate predictions of the sensitivity for the expected GRB rate to be observed. MIRAX will be capable of detecting ∼44 GRBs per year up to redshifts of ∼4.5. The MIRAX mission will be able to contribute significantly to GRB science by detecting a large number of GRBs per year with wide band spectral response. The observations will contribute mainly to the part of GRB spectra where a thermal emission is predicted by the Fireball model. We also discuss the possibility of detecting GRB afterglows in the X-ray band with MIRAX.

  1. Probing Dust with Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Watson, D.

    2009-12-01

    Long-duration gamma-ray bursts (GRBs) result from the deaths of certain massive stars. Since GRBs occur in actively star-forming regions, there should be significant dust extinction of their optical afterglows. The dust properties of GRB environments are of interest not only for their value in studies of GRB and their formation, but also because GRBs occur in star-forming galaxies at very high redshifts (currently = 2.2), and GRB afterglows give us a means to study dust and metallicity in the hearts of extremely distant star-forming regions that are accessible in no other way. Their brightness and simple, power-law spectra across a wide wavelength range, makes them well-suited to extinction studies in star-forming regions at all redshifts. The vast majority of reddening curves have been featureless—the 2175 Å bump for example has only been detected in a GRB host galaxy for the first time very recently and is presented here. Another new, unusual extinction curve is also briefly presented. Extinctions derived solely from the reddening in GRB optical/near IR spectra have so far been relatively low and at the same time those reddening measurements disagree strongly with extinctions inferred from metallicity measurements and have led to the suggestion of a flat dust extinction curve (grey dust), possibly because of dust destruction by the GRB. In spite of the large literature on grey dust and the alteration of the extinction curve by dust destruction, its existence has so far never been demonstrated because of the difficulty in obtaining absolute extinction curves.

  2. LOCALIZATION OF GAMMA-RAY BURSTS USING THE FERMI GAMMA-RAY BURST MONITOR

    SciTech Connect

    Connaughton, V.; Briggs, M. S.; Burgess, J. M.; Goldstein, A.; Wilson-Hodge, C. A.; Paciesas, W. S.; Preece, R. D.; Gibby, M. H.; Greiner, J.; Yu, H.-F.; Gruber, D.; Kippen, R. M.; Byrne, D.; Fitzpatrick, G.; Foley, S.; and others

    2015-02-01

    The Fermi Gamma-ray Burst Monitor (GBM) has detected over 1400 gamma-ray bursts (GRBs) since it began science operations in 2008 July. We use a subset of over 300 GRBs localized by instruments such as Swift, the Fermi Large Area Telescope, INTEGRAL, and MAXI, or through triangulations from the InterPlanetary Network, to analyze the accuracy of GBM GRB localizations. We find that the reported statistical uncertainties on GBM localizations, which can be as small as 1°, underestimate the distance of the GBM positions to the true GRB locations and we attribute this to systematic uncertainties. The distribution of systematic uncertainties is well represented (68% confidence level) by a 3.°7 Gaussian with a non-Gaussian tail that contains about 10% of GBM-detected GRBs and extends to approximately 14°. A more complex model suggests that there is a dependence of the systematic uncertainty on the position of the GRB in spacecraft coordinates, with GRBs in the quadrants on the Y axis better localized than those on the X axis.

  3. Gamma-ray bursts and radio pulsar glitches

    SciTech Connect

    Hartmann, D.; Hurley, K.; Niel, M. California University, Berkeley Centre d'Etude Spatiale des Rayonnements, Toulouse, )

    1992-03-01

    Upper limits to gamma-ray fluxes produced in conjunction with a radio pulsar glitch are presented. The glitch occurred on the Vela pulsar on December 24, 1988 and was the first to be observed as it occurred. Sensitive gamma-ray burst detectors aboard the Phobos 2 spacecraft were operating at this time, but recorded no significant burst at the time of the glitch. It is concluded that if a gamma-ray burst was generated in the energy range to which the Phobos detectors were sensitive, and if it was not beamed away from the spacecraft, the efficiency of glitch energy conversion into gamma-rays could not have exceeded 10 exp -4. 27 refs.

  4. A gamma-ray burst monitor for GLAST

    NASA Astrophysics Data System (ADS)

    von Kienlin, A.; Briggs, M. S.; Diehl, R.; Fishman, G. J.; Georgii, R.; Kippen, R. M.; Kouveliotou, C.; Lichti, G. G.; Meegan, C. A.; Paciesas, W. S.; Preece, R. D.; Schönfelder, V.

    2001-09-01

    The Gamma-Ray Large-Area Space Telescope GLAST is the next NASA mission in the high-energy γ-ray regime (10 MeV to about 500 GeV), with launch anticipated in 2006 (Gehrels, 1999). Recently a design using silicon strips for the electron-positron pair tracking was selected for the main instrument. One of the key scientific objectives of the GLAST mission is to determine the high-energy behaviour of gamma-ray bursts and transients. The importance of studying bursts with GLAST has been emphasized by choosing a burst monitor as the secondary instrument on GLAST. A proposal to the NASA AO for such a burst monitor was submitted jointly by a collaboration between the Marshall Space-Flight Center/University of Alabama (both in Huntsville/Alabama) and the Max-Planck-Institut für extraterrestrische Physik in Garching. This GLAST Burst Monitor will complement the main instrument information about bursts in the energy range between 5 keV and 30 MeV. It will provide real-time burst locations over a wide FOV with sufficient accuracy to repoint the GLAST spacecraft. Time-resolved spectra of many bursts recorded with GLAST and the burst monitor will cover unprecedented 6 decades of energy. This will help to advance our understanding of the mechanisms by which gamma-rays are generated in gamma-ray bursts. Mid of March 2000 this proposal for GLAST's burst monitor has been selected.

  5. Gamma-ray burst results from DMSP satellites

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R.W.; Griffee, J.W.

    1992-12-01

    Gamma-ray burst detectors are aboard three US Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, in orbit at 800 km altitude. A large number of bursts have been detected by DMSP, often confirming and supplementing data from GRO and other spacecraft, sometimes detecting bursts not otherwise known. The position of an unknown source may be considerably restricted by knowledge of the several DMSP spacecraft locations and fields of view. These data may be of considerable assistance in understanding the gamma-ray burst phenomenon.

  6. Gamma-ray burst results from DMSP satellites

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R.W. ); Griffee, J.W. )

    1993-07-05

    Gamma-ray burst detectors are aboard three U.S. Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, in orbit at 800 km altitude. A large number of burst have been detected by DMSP, often confirming and supplementing data from GRO and other spacecraft, sometimes detecting bursts not othewise known. The position of an unknown source may be considerably restricted by knowledge of the several DMSP spacecraft locations and fields of view. These data may be of considerable assistance in understanding the gamma-ray burst phenomenon.

  7. Observation of gamma-ray bursts with the SMM gamma-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Strickman, M. S.; Kinzer, R. L.; Chupp, E. L.; Forrest, D. J.; Ryan, J. M.; Rieger, E.; Reppin, C.; Kanbach, G.

    1982-01-01

    The gamma-ray spectrometer on SMM is sensitive to bursts within its field of view with intensities greater than 0.000005 erg/sq cm above 100 keV. It has detected 17 events between February 1980 and March 1981 with the characteristics of cosmic gamma-ray bursts. The most intense burst, on 19 April 1980, had a photon spectrum consistent with a power law with spectral index - 2.5 from 300 keV to approximately 7 MeV. It is not possible at present to exclude the sun as the source of this burst. Spectra of 11 of the bursts have been studied for line features with no clear evidence for line emission greater than 300 keV. The continuum radiation from about half of these events have hard emission extending to approximately equal to or greater than 2 MeV.

  8. Observation of gamma-ray bursts with the SMM gamma-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Share, G. H.; Strickman, M. S.; Kinzer, R. L.; Chupp, E. L.; Forrest, D. J.; Ryan, J. M.; Rieger, E.; Reppin, C.; Kanbach, G.

    1982-01-01

    The gamma-ray spectrometer on SMM is sensitive to bursts within its field of view with intensities greater than 0.000005 erg/sq cm above 100 keV. It has detected 17 events between February 1980 and March 1981 with the characteristics of cosmic gamma-ray bursts. The most intense burst, on 19 April 1980, had a photon spectrum consistent with a power law with spectral index - 2.5 from 300 keV to approximately 7 MeV. It is not possible at present to exclude the sun as the source of this burst. Spectra of 11 of the bursts have been studied for line features with no clear evidence for line emission greater than 300 keV. The continuum radiation from about half of these events have hard emission extending to approximately equal to or greater than 2 MeV.

  9. Gamma-Ray Bursts Search with HAWC

    NASA Astrophysics Data System (ADS)

    de Leon, Cederik; Salazar Ibarguen, Humberto; Villaseã+/-Or Cendejas, Luis Manuel; HAWC Collaboration

    2017-01-01

    The High Altitude Water Cherenkov (HAWC) Gamma-ray observatory is a wide field-of-view observatory sensitive to gamma rays in the 100 GeV - 100 TeV energy range, located in Mexico at an altitude of 4100 m. In the present work we present results on the search for excesses in the rates of signals from the individual photomultiplier tubes (PMTs) using the Time to Digital Converters (TDC) of HAWC. This search is based on the implementation of the Moving Average Ratio Analysis (MARA) focused on the characterization of the different physical phenomena that may give rise to such excesses: noise in the PMTs, atmospheric conditions related with thunderstorms and excesses of astrophysical origin such as variable sources of high energy gamma rays and in particular GRBs. In particular we present an analysis over the HAWC historical data for the search of such excesses and elaborate on the possible physical interpretation of the found excesses.

  10. Prompt optical emission from gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Kehoe, Robert; Akerlof, Karl; Balsano, Richard; Barthelmy, Scott; Bloch, Jeff; Butterworth, Paul; Casperson, Don; Cline, Tom; Fletcher, Sandra; Frontera, Fillippo; Gisler, Galen; Heise, John; Hills, Jack; Hurley, Kevin; Lee, Brian; Marshall, Stuart; McKay, Tim; Pawl, Andrew; Piro, Luigi; Priedhorsky, Bill; Szymanski, John; Wren, Jim

    The Robotic Optical Transient Search Experiment (ROTSE) seeks to measure contemporaneous and early afterglow optical emission from gamma-ray bursts (GRBs). The ROTSE-I telescope array has been fully automated and responding to burst alerts from the GRB Coordinates Network since March 1998, taking prompt optical data for 30 bursts in its first year. We will briefly review observations of GRB990123 which revealed the first detection of an optical burst occurring during the gamma-ray emission, reaching 9th magnitude at its peak. In addition, we present here preliminary optical results for seven other gamma-ray bursts. No other optical counterparts were seen in this analysis, and the best limiting senisitivities are mV > 13.0 at 14.7 seconds after the gamma-ray rise, and mmV > 16.4 at 62 minutes. These are the most stringent limits obtained for GRB optical counterpart brightness in the first hour after the burst. This analysis suggests that there is not a strong correlation between optical flux and gamma-ray emission.

  11. "Short, Hard Gamma-Ray Bursts - Mystery Solved?????"

    NASA Technical Reports Server (NTRS)

    Parsons, A.

    2006-01-01

    After over a decade of speculation about the nature of short-duration hard-spectrum gamma-ray bursts (GRBs), the recent detection of afterglow emission from a small number of short bursts has provided the first physical constraints on possible progenitor models. While the discovery of afterglow emission from long GRBs was a real breakthrough linking their origin to star forming galaxies, and hence the death of massive stars, the progenitors, energetics, and environments for short gamma-ray burst events remain elusive despite a few recent localizations. Thus far, the nature of the host galaxies measured indicates 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. On the other hand, some of the short burst afterglow observations cannot be easily explained in the coalescence scenario. These observations raise the possibility that short GRBs may have different or multiple progenitors systems. The study of the short-hard GRB afterglows has been made possible by the Swift Gamma-ray Burst Explorer, launched in November of 2004. Swift is equipped with a coded aperture gamma-ray telescope that can observe up to 2 steradians of the sky and can compute the position of a gamma-ray burst to within 2-3 arcmin in less than 10 seconds. The Swift spacecraft can slew on to this burst position without human intervention, allowing its on-board x ray and optical telescopes to study the afterglow within 2 minutes of the original GRB trigger. More Swift short burst detections and afterglow measurements are needed before we can declare that the mystery of short gamma-ray burst is solved.

  12. Constraints of the Luminosities of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Hakkila, J.; Meegan, C.; Horack, J.; Pendleton, G.; Briggs, M.; Paciesas, W.; Emslie, G.; Mallozzi, R.

    1995-09-01

    Constraints are found on the gamma-ray burst luminosity function from an analysis of the combined BATSE/PVO intensity distribution. If bursts originate in an extended Galactic halo, then the intrinsic luminosity range is narrow, with bursts spanning only a factor of five or less in luminosity. If bursts originate in a simple Friedmann cosmology with Ω = 1 and Λ = 0, then very few luminosity constraints exist.

  13. Physical processes and diagnostics of gamma-ray burst emission

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    1992-01-01

    With improved data from BATSE and other instruments, it is important to develop a range of diagnostic tools to link gamma-ray burst observations with theory. I will review some of the physical processes which may take place to form the spectrum of gamma-ray burst sources, assuming that the bursts originate on strongly magnetized neutron stars. The important diagnostics that these processes provide to probe the emission region and how they might be used to interpret observed spectra will also be discussed.

  14. Gamma Ray Burst Follow-Ups with Bootes-4

    NASA Astrophysics Data System (ADS)

    Guziy, Sergey; Castro-Tirado, Guziy, Alberto J.; Jelinek, Martin; Gorosabel, Javier; Kubanek, Petr; Cunniffe, Ronan; Lara-Gil, Oscar; Tello, Juan C.; Jeong, Soomin; Oates, Samantha R.; Xu, Youdong; Perez-Ramirez, Dolores; Cui, Chenzou; Fan, Yufeng; Wan, Chuanjun; Bai, Jinming; Kheyfets, I.

    The Burst Observer and Optical Transient Exploring System (BOOTES), is a global robotic observatory network, which started in 1998 with Spanish leadership devoted to study optical emissions from gamma ray bursts (GRBs) that occur in the Universe. We present shot history and current status of BOOTES-4 telescope. Some details of 38 GRBs followed-up with BOOTES-4 are discussed.

  15. Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

    1992-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

  16. Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

    1992-01-01

    The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

  17. Gamma-Ray Bursts: Sans Second Postulate

    NASA Astrophysics Data System (ADS)

    Fritzius, R.

    stars starting with Cepheid variables. The author cleared up a critical flaw in Sekerin's reasoning regarding the computed value of the periodic spectral variations involved, and created software simulations of binary star orbits which produce the light curves and spectral variations predicted by the Ritzian theory. (Constant speed-of-light simulations do not produce the variations.) A limited number of these simulations including some for various kinds of Gamma-Ray Bursts (GRBs) are to be shown as part of this presentation. High-resolution spectral studies of variable stars, including GRBs, may eventually help us decide whether or not Ritz was as wrong as is currently generally thought. Further information on this topic is available at: http://www.ebicom.net/~rsf1/binaries.htm

  18. Gamma-ray burst locations from the Burst and Transient Source Experiment

    NASA Technical Reports Server (NTRS)

    Brock, M. N.; Meegan, C. A.; Roberts, F. E.; Fishman, G. J.; Wilson, R. B.; Paciesas, W. S.; Pendleton, G. N.

    1992-01-01

    The Burst and Transient Source Experiment (BATSE) consists of eight anisotropic gamma-ray spectrometers at the corners of the Compton Gamma Ray Observatory. BATSE monitors the full sky from a fixed orientation and determines the direction of gamma-ray bursts with an accuracy appropriate for studying the bursts' celestial distribution. We describe the calculation of gamma-ray burst directions from measurements made by BATSE. We present a sample of calculated directions from BATSE's measurement of solar flaxes and compare the calculated directions with the solar direction. We describe the systematic errors apparent in these data and discuss ongoing efforts to correct them.

  19. MAGNETIC STRUCTURES IN GAMMA-RAY BURST JETS PROBED BY GAMMA-RAY POLARIZATION

    SciTech Connect

    Yonetoku, Daisuke; Murakami, Toshio; Morihara, Yoshiyuki; Takahashi, Takuya; Wakashima, Yudai; Yonemochi, Hajime; Sakashita, Tomonori; Fujimoto, Hirofumi; Kodama, Yoshiki; Gunji, Shuichi; Toukairin, Noriyuki; Mihara, Tatehiro; Toma, Kenji

    2012-10-10

    We report polarization measurements in two prompt emissions of gamma-ray bursts, GRB 110301A and GRB 110721A, observed with the gamma-ray burst polarimeter (GAP) on borad the IKAROS solar sail mission. We detected linear polarization signals from each burst with polarization degree of {Pi} = 70 {+-} 22% with statistical significance of 3.7{sigma} for GRB 110301A, and {Pi} = 84{sup +16}{sub -28}% with 3.3{sigma} confidence level for GRB 110721A. We did not detect any significant change of polarization angle. These two events had shorter durations and dimmer brightness compared with GRB 100826A, which showed a significant change of polarization angle, as reported in Yonetoku et al. Synchrotron emission model can be consistent with the data of the three GRBs, while the photospheric quasi-thermal emission model is not favored. We suggest that magnetic field structures in the emission region are globally ordered fields advected from the central engine.

  20. The Fermi Gamma-ray Burst Monitor Instrument

    SciTech Connect

    Bhat, P. N.; Briggs, M. S.; Connaughton, V.; Paciesas, W. S.; Preece, R. D.; Meegan, C. A.; Lichti, G. G.; Diehl, R.; Greiner, J.; Kienlin, A. von; Fishman, G. J.; Kouveliotou, C.; Kippen, R. M.

    2009-05-25

    The Fermi Gamma-ray Space Telescope launched on June 11, 2008 carries two experiments onboard--the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). The primary mission of the GBM instrument is to support the LAT in observing {gamma}-ray bursts (GRBs) by providing low-energy measurements with high temporal and spectral resolution as well as rapid burst locations over a large field-of-view ({>=}8 sr). The GBM will complement the LAT measurements by observing GRBs in the energy range 8 keV to 40 MeV, the region of the spectral turnover in most GRBs. The GBM detector signals are processed by the onboard digital processing unit (DPU). We describe some of the hardware features of the DPU and its expected limitations during intense triggers.

  1. Observations of Gamma-Ray Bursts with INTEGRAL

    SciTech Connect

    McGlynn, S.; Hanlon, L.; McBreen, B.; Foley, S.; French, J.; Melady, G.; McBreen, S.; Kienlin, A. von; Preece, R.

    2006-05-19

    The INTEGRAL satellite has two coded-mask {gamma}-ray instruments; the spectrometer (SPI) which is optimised for high resolution {gamma}-ray line spectroscopy, and the imager (IBIS) which can localise GRBs to a precision of a few arcminutes. INTEGRAL was launched 3 years ago and the INTEGRAL Burst Alert System (IBAS) has detected 33 long duration GRBs, the most intense burst by far being GRB 041219 which also had prompt optical emission associated with it. The {gamma}-ray properties of some of these bursts are presented with particular emphasis on spectral results. A subset of 6 GRBs were observed with XMM-Newton and a selection of these results is presented. New results from recent GRBs are also discussed.

  2. Searches for gravitational waves associated with gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Talukder, Dipongkar

    2014-08-01

    Gamma-ray bursts are likely related to several processes linked to catastrophic stellar events. The progenitor scenarios of gamma-ray bursts include mergers of binary systems composed of neutron stars or a neutron star and a stellar-mass black hole, core collapse of massive stars, and perturbed neutron stars. Gravitational-wave emission is expected to accompany such events. We discuss the strategies developed to search for gravitational waves associated with these events and the search results from the initial LIGO and Virgo detectors. We also discuss the prospects for such searches with advanced LIGO and Virgo detectors. In order to provide quick feedback, we are developing promptly launched gravitational-wave data analyses for the gamma-ray bursts observed by the Swift and Fermi satellites.

  3. The Fourth BATSE Gamma-Ray Burst Catalog. Revised

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Meegan, Charles A.; Pendleton, Geoffrey N.; Briggs, Michael S.; Kouveliotou, Chryssa; Koshut, Thomas M.; Lestrade, John Patrick; McCollough, Michael L.; Brainerd, Jerome J.; Hakkila, Jon

    1999-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) has triggered on 1637 cosmic gamma-ray bursts between 1991 April 19 and 1996 August 29. These events constitute the Fourth BATSE burst catalog. The current version (4Br) has been revised from the version first circulated on CD-ROM in 1997 September (4B) to include improved locations for a subset of bursts that have been reprocessed using additional data. A significant difference from previous BATSE catalogs is the inclusion of bursts from periods when the trigger energy range differed from the nominal 50-300 keV. We present tables of the burst occurrence times, locations, peak fluxes, fluences, and durations. In general, results from previous BATSE catalogs are confirmed here with greater statistical significance.

  4. The Fourth BATSE Gamma-Ray Burst Catalog. Revised

    NASA Technical Reports Server (NTRS)

    Paciesas W. S.; Meegan, Charles A.; Pendleton, Geoffrey N.; Briggs, Michael S.; Kouveliotou, Chryssa; Koshut, Thomas M.; Lastrade, J. P.; McCollough, M. L.; Brainerd, Jerome J.; Hakkila, Jon; hide

    1998-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) has triggered on 1637 cosmic gamma-ray bursts between 1991 April 19 and 1996 August 29. These events constitute the Fourth BATSE burst catalog. The current version (4Br) has been revised from the version first circulated on CD-ROM in September 1997 (4B) to include improved locations for a subset of bursts that have been reprocessed using additional data. A significant difference from previous BATSE catalogs is the inclusion of bursts from periods when the trigger energy range differed from the nominal 50-300 keV. We present tables of the burst occurrence times, locations, peak fluxes, fluences, and durations. In general, results from previous BATSE catalogs are confirmed here with greater statistical significance.

  5. Systematic Effects on Duration Measurements of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Koshut, Thomas M.; Paciesas, William S.; Kouveliotou, Chryssa; vanParadijs, Jan; Pendleton, Geoffrey N.; Fishman, Gerald J.; Meegan, Charles A.

    1996-01-01

    The parameters T(sub 90) and T(sub 50) have recently been introduced as a measurement of the duration of gamma-ray bursts. We present here a description of the method of measuring T(sub 90) and T(sub 50) and its application to gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO). We use simulated as well as observed time profiles to address some of the possible systematic effects affecting individual T(sub 90) (T(sub 50)) measurements. We show that these systematic effects do not mimic those effects that would result from time dilation if the burst sources are at distances of several Gpc. We discuss the impact of these systematic effects on the T(sub 90) (T(sub 50)) distributions for the gamma-ray bursts observed with BATSE. We distinguish between various types of T(sub 90) (T(sub 50)) distributions, and discuss the ways in which distributions observed with different experiments can vary, even though the measurements for commonly observed bursts may be the same. We then discuss the distributions observed with BATSE and compare them to those observed with other experiments.

  6. LAT Automated Science Processing for Gamma-Ray Bursts

    SciTech Connect

    Chiang, James

    2007-05-01

    The LAT Instrument Science Operations Center (ISOC) will perform various tasks to support coordination of multiwavelength observations for transient sources. In this paper, we describe the prototype implementation of the Automated Science Processing (ASP) for the detection and analysis of gamma-ray bursts (GRBs) in LAT and GBM data. The GRB-related tasks include: position refinement using LAT data given initial GBM or GCN locations, spectral analysis using LAT data alone, joint spectral fitting with GBM data, gamma-ray afterglow detection and characterization, and blind searches for prompt burst emission in LAT data.

  7. Gamma Ray Bursts: an Enigma Being Unraveled

    SciTech Connect

    De Rujula, Alvaro

    2003-05-14

    The best astrophysical accelerators are quasars and the 'progenitors' of GRBs which, after decades of observations and scores of theories, we still do not understand. But, I shall argue, we now know quite well where GRBs come from, and we understand how their 'beams' behave, as they make short pulses of gamma rays and long-duration X-ray, optical and radio 'afterglows'. I shall argue that our understanding of these phenomena, based on the 'Cannonball Model', is unusually simple, precise and successful. The 'sociology' of GRBs is interesting per se and, in this sense, the avatars of the Cannonball Model in confronting the generally accepted 'fireball models' are also quite revealing.

  8. DMSP satellites as gamma-ray burst detectors

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R.W. ); Griffee, J.W. )

    1994-07-01

    Gamma-ray burst detectors are aboard three U. S. Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, in orbit at 800 km altitude, with corresponding fields of view to 117[degree] from the zenith. A large number of bursts have been detected by DMSP, usually confirming and supplementing data from GRO and other spacecraft. The location of a gamma-ray burst source detected by several DMSP spacecraft is considerably restricted by knowledge of the several fields of view. Often non-detection of a strong burst by one or more DMSP spacecraft is even more informative in narrowing the possible area of the burst. The DMSP data in conjunction with observations by other spacecraft can lead to reasonable positional information when more accurate positions are not from GRO or other data.

  9. Observing gamma-ray bursts with the INTEGRAL spectrometer SPI

    NASA Technical Reports Server (NTRS)

    Skinner, G. K.; Connell, P. H.; Naya, J. E.; Seifert, H.; Teegarden, B. J.

    1997-01-01

    The spectrometer for INTEGRAL (SPI) is a germanium spectrometer with a wide field of view and will provide the International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission with the opportunity of studying gamma ray bursts. Simulations carried out to assess the response of the instrument using data from real burst data as input are reported on. It is shown that, despite the angular resolution of 3 deg, it is possible to locate the direction of bursts with an accuracy of a few arcmin, while offering the high spectral resolution of the germanium detectors. It is remarked that the SPI field of view is similar to the size of the halo of bursts expected around M 31 on galactic models. The detectability of bursts with such a halo is discussed.

  10. Intensity distributions of gamma-ray bursts

    SciTech Connect

    Band, D. L.

    2001-01-01

    Observations of individual bursts chosen by the vagaries of telescope availability demonstrated that bursts are not standard candles and that their apparent energy can be as great as 10{sup 54} erg. However, determining the distribution of their apparent energy (and of other burst properties) requires the statistical analysis of a well-defined burst sample; the sample definition includes the threshold for including a burst in the sample. Thus optical groups need to the criteria behind the decision to search for a spectroscopic redshift. Currently the burst samples are insufficient to choose between lognormal and power law functional forms of the distribution, and the parameter values for these functional forms differ between burst samples. Similarly, the actual intensity distribution may be broader than observed, with a low energy tail extending below the detection threshold.

  11. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    SciTech Connect

    Pal'shin, V. D.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Oleynik, P. P.; Ulanov, M. V.; Hurley, K.; Cline, T.; Trombka, J.; McClanahan, T.; Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B.; and others

    2013-08-15

    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, {approx}18 yr{sup -1}, exceeds that of many individual experiments.

  12. Comptel measurements of the gamma-ray burst GRB 930131

    NASA Technical Reports Server (NTRS)

    Ryan, J.; Bennett, K.; Collmar, W.; Connors, A.; Fishman, G. J.; Greiner, J.; Hanlon, L. O.; Hermsen, W.; Kippen, R. M.; Kouveliotou, C.

    1994-01-01

    On 1993 January 31 at 1857:12 Universal Time (UT), the Imaging Compton Telescope COMPTEL onboard the Compton Gamma Ray Observatory (CGRO) detected the cosmic gamma-ray burst GRB 930131. COMPTEL's MeV imaging capability was employed to locate the source to better than 2 deg (1 sigma error radius) within 7 hr of the event, initiating a world-wide search for an optical and radio counterpart. The maximum likelihood position of the burst from the COMPTEL data is alpha(sub 2000) = 12h 18m, delta(sub 2000) = -9 deg 42 min, consistent with independent CGRO-Burst and Transient Source Experiment (CGRO-BATSE) and Energetic Gamma Ray Experiment Telescope (EGRET) locations as well as with the triangulation annulus constructed using BATSE and Ulysses timing data. The combined COMPTEL and EGRET burst data yield a better estimate of the burst location: alpha(sub 2000) = 12h 18m and delta(sub 2000) = -10 deg 21 min, with a 1 sigma error radius of 32 min. In COMPTEL's energy range, this burst was short, consisting of two separate spikes occurring within a approximately 1 s interval with a low intensity tail for approximately 1 s after the second spike. No statistically significant flux is present for a 30 s period after the main part of the burst. This is consistent with the EGRET data. The COMPTEL telescope events indicate a hard, power-law emission extending to beyond 10 MeV with a spectral index of -1.8 +/- 0.4. The rapid fluctuations and high intensities of the gamma-ray flux greater than 10 MeV place the burst object no farther than 250 pc if the burst emission is not beamed.

  13. The radio Aftreglows of Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Dado, S.; Dar, A.; de Rujula, A.

    The best cosmic accelerators are quasars and the GRB projenitors. After decades of observations and scores of theories, we still do not know how they work. But, I shall argue, we now know quite well where GRBs come from and we understand how, their ``beams'' behave, as they make short pulses of gamma rays and long-duration X- ray, optical and radio ``afterglows''. For the afterglows ---on which I shall concentrate--- our understanding, based on the ``Cannonball Model'', is extraordinarily simple, precise and successful. Standard candles live and die and, since GRBs are being understood and are very distant, they may be about to be incarnated as such. The ``sociology'' of GRBs is interesting per se, the avatars of the Cannonball Model are also significant in this sense.

  14. AGILE and Gamma-Ray Bursts

    SciTech Connect

    Longo, Francesco; Tavani, M.; Barbiellini, G.; Argan, A.; Basset, M.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Cattaneo, P.; Chen, A.; Costa, E.; Del Monte, E.; Di Cocco, G.; Di Persio, G.; Donnarumma, I.; Feroci, M.; Fiorini, M.; Foggetta, L.; Froysland, T.; Frutti, M.

    2006-05-19

    AGILE is a Scientific Mission dedicated to high-energy astrophysics supported by ASI with scientific participation of INAF and INFN. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV. The broadband detection of GRBs and the study of implications for particle acceleration and high energy emission are primary goals of th emission. AGILE can image GRBs with 2-3 arcminutes error boxes in the hard X-ray range, and provide broadband photon-by photon detection in the 15-45 keV, 03-50 MeV, and 30 MeV-30 GeV energy ranges. Microsecond on-board photon tagging and a {approx} 100 microsecond gamma-ray detection deadtime will be crucial for fast GRB timing. On-board calculated GRB coordinates and energy fluxes will be quickly transmitted to the ground by an ORBCOMM transceiver. AGILE have recently (December 2005) completed its gamma-ray calibration. It is now (January 2006) undergoing satellite integration and testing. The PLSV launch is planned in early 2006. AGILE is then foreseen to be fully operational during the summer of 2006. It will be the only mission entirely dedicated to high-energy astrophysics above 30 MeV during the period mid-2006/mid-2007.

  15. Gamma Ray Bursts and the Birth of Black Holes

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2009-01-01

    Black holes have been predicted since the 1940's from solutions of Einstein's general relativity field equation. There is strong evidence of their existence from astronomical observations, but their origin has remained an open question of great interest. Gamma-ray bursts may the clue. They are powerful explosions, visible to high redshift, and appear to be the birth cries of black holes. The Swift and Fermi missions are two powerful NASA observatories currently in orbit that are discovering how gamma-ray bursts work. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type II and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are tremendously luminous and are providing a new tool to study the high redshift universe. One Swift burst at z=8.3 is the most distant object known in the universe. The talk will present the latest gamma-ray burst results from Swift and Fermi and will highlight what they are teaching us about black holes and jet outflows.

  16. Gamma Ray Bursts and the Birth of Black Holes

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2009-01-01

    Black holes have been predicted since the 1940's from solutions of Einstein's general relativity field equation. There is strong evidence of their existence from astronomical observations, but their origin has remained an open question of great interest. Gamma-ray bursts may the clue. They are powerful explosions, visible to high redshift, and appear to be the birth cries of black holes. The Swift and Fermi missions are two powerful NASA observatories currently in orbit that are discovering how gamma-ray bursts work. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type II and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are tremendously luminous and are providing a new tool to study the high redshift universe. One Swift burst at z=8.3 is the most distant object known in the universe. The talk will present the latest gamma-ray burst results from Swift and Fermi and will highlight what they are teaching us about black holes and jet outflows.

  17. On the extragalactic origin of gamma-ray bursts

    SciTech Connect

    Johnson, M.; Teller, E.

    1984-11-02

    A theory to explain the origin of extragalactic gamma ray bursts is presented. Collisions of black dwarf and neutron stars with a subsequent fragmentation of the dwarf producing relativistic particle accelerations toward the neutron star and a resulting turbulent flow of material at the neutron star surface is postulated. (DWL)

  18. The NuSTAR View of Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Kouveliotou, C.

    2014-01-01

    The Nuclear Spectroscopic Telescope Array (NuSTAR) mission was launched June 13, 2012. During the next two pears NuSTAR observed two Gamma Ray Bursts, GRBs 130427A and 130925A. I will describe here the NuSTAR GRB results and discuss their implications on the GRB field.

  19. Constraints on relativity violations from gamma-ray bursts.

    PubMed

    Kostelecký, V Alan; Mewes, Matthew

    2013-05-17

    Tiny violations of the Lorentz symmetry of relativity and the associated discrete CPT symmetry could emerge in a consistent theory of quantum gravity such as string theory. Recent evidence for linear polarization in gamma-ray bursts improves existing sensitivities to Lorentz and CPT violation involving photons by factors ranging from ten to a million.

  20. Gamma-ray burst color-color diagrams

    NASA Technical Reports Server (NTRS)

    Kouveliotou, C.; Paciesas, W. S.; Fishman, G. J.; Meegan, C. A.; Wilson, R. B.

    1993-01-01

    We calculate the spectral hardness ratios for several intense gamma-ray bursts (GRBs) which have sufficient statistics in four energy channels. We study the evolution of these hardness ratios during the events using color-color diagrams (CCDs) and we attempt a preliminary classification of GRBs based on their CCD evolution.

  1. Search for gamma ray bursts with coincident balloon flights

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Schmidt, W. K. H.; Teegarden, B. J.

    1976-01-01

    A search was conducted for cosmic gamma ray bursts of small size and of sufficient frequency of occurrence to be detected during a one day observation program. Two similar detectors, successfully balloon-borne from launch sites in South Dakota and Texas, achieved about 20 hours of simultaneous operation at several millibars atmospheric depth, with continuous separation of over 1,500 km. Fluctuations of the counting rates of less than 150 keV photons with temporal structures from microseconds to several minutes were compared in order to detect coincident or associated responses from the two instruments. No coincident gamma-ray burst events were detected. The resulting integral size spectrum of small bursts, from this and from all other searches, remains a spectrum of upper limits, consistent with an extrapolation of the size spectrum of the largest known bursts, fitting a power low of index -1.5.

  2. Quark stars as inner engines for Gamma ray bursts?

    NASA Astrophysics Data System (ADS)

    Ouyed, R.; Sannino, F.

    2002-05-01

    A model for Gamma ray bursts inner engine based on quark stars (speculated to exist in nature) is presented. We describe how and why these objects might constitute new candidates for GRB inner engines. At the heart of the model is the onset of exotic phases of quark matter at the surface of such stars, in particular the 2-flavor color superconductivity. A novel feature of such a phase is the generation of particles which are unstable to photon decay providing a natural mechanism for a fireball generation; an approach which is fundamentally different from models where the fireball is generated during collapse or conversion of neutron star to quark star processes. The model is capable of reproducing crucial features of Gamma ray bursts, such as the episodic activity of the engine (multiple and random shell emission) and the two distinct categories of the bursts (two regimes are isolated in the model with ~ 2 s and ~ 81 s burst total duration).

  3. LAT Onboard Science: Gamma-Ray Burst Identification

    SciTech Connect

    Kuhn, Frederick; Bonnell, Jerry; Hughes, Richard; Norris, Jay; Ritz, Steven; Russell, James; Smith, Patrick; Winer, Brian; /Ohio State U.

    2007-10-15

    The main goal of the Large Area Telescope (LAT) onboard science program is to provide quick identification and localization of Gamma Ray Bursts (GRB) onboard the LAT for follow-up observations by other observatories. The GRB identification and localization algorithm will provide celestial coordinates with an error region that will be distributed via the Gamma ray burst Coordinate Network (GCN). We present results that show our sensitivity to bursts as characterized using Monte Carlo simulations of the GLAST observatory. We describe and characterize the method of onboard track determination and the GRB identification and localization algorithm. Onboard track determination is considerably different than in the onground case, resulting in a substantially altered point spread function. The algorithm contains tunable parameters which may be adjusted after launch when real bursts characteristics at very high energies have been identified.

  4. LAT Onboard Science: Gamma-Ray Burst Identification

    SciTech Connect

    Kuehn, Frederick; Hughes, Richard; Smith, Patrick; Winer, Brian; Bonnell, Jerry; Norris, Jay; Ritz, Steven; Russell, James

    2007-07-12

    The main goal of the Large Area Telescope (LAT) onboard science program is to provide quick identification and localization of Gamma Ray Bursts (GRB) onboard the LAT for follow-up observations by other observatories. The GRB identification and localization algorithm will provide celestial coordinates with an error region that will be distributed via the Gamma ray burst Coordinate Network (GCN). We present results that show our sensitivity to bursts as characterized using Monte Carlo simulations of the GLAST observatory. We describe and characterize the method of onboard track determination and the GRB identification and localization algorithm. Onboard track determination is considerably different than in the on-ground case, resulting in a substantially altered point spread function. The algorithm contains tunable parameters which may be adjusted after launch when real bursts characteristics at very high energies have been identified.

  5. Neutron star mergers and gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Narayan, Ramesh

    1993-01-01

    Under the support of grant NAG 5-1904, we have carried out research on several topics related to gamma-ray bursts (GRB's). In our proposal, we stated that we would study three topics: (1) fireball evolution; (2) neutron star mergers; and (3) statistics of bursts. We have completed a significant amount of work in each of these areas. Resulting papers from this work are presented.

  6. SCIENCE Magazine: BATSE 1000 gamma-ray burst perspective

    NASA Technical Reports Server (NTRS)

    Horack, John M.

    1995-01-01

    A historical highlight and analysis of the Burst and Transient Source Experiment (BATSE), which has been in operation for more than three years and has detected more than 1,000 cosmic gamma-ray bursts is presented. The questions BATSE has answered and those it has not are assessed, along with the problems and data correlation and processing that has occured from the BATSE operation.

  7. Gamma Ray Burst Discoveries by the Swift Mission

    NASA Astrophysics Data System (ADS)

    Gehrels, N.; Swift Team

    2005-12-01

    Gamma-ray bursts are among the most fascinating occurrences in the cosmos. They are thought to be the birth cries of black holes throughout the universe. The NASA Swift mission is an innovative new multiwavelength observatory designed to determine the origin of bursts and use them to probe the early Universe. Swift is now in orbit after a beautiful launch on November 20, 2004. A new-technology wide-field gamma-ray camera detects more than a hundred bursts per year. Sensitive narrow-field X-ray and UV/optical telescopes, built in collaboration with UK and Italian partners, are pointed at the burst location in 20 to 70 sec by an autonomously controlled "swift" spacecraft. For each burst, arcsec positions are determined and optical/UV/X-ray/gamma-ray spectrophotometry performed. Information is also rapidly sent to the ground to a team of more than 50 observers at telescopes around the world. The first year of findings from the mission will be presented. The long-standing mystery of short GRBs has been solved, and the answer is the most interesting possible scenario. High redshift bursts have been detected leading to a better understanding of star formation rates and distant galaxy environments. GRBs have been found with giant X-ray flares occurring in their afterglow. These, and other topics, will be discussed.

  8. Gamma-ray bursts from extinct neutron stars

    NASA Technical Reports Server (NTRS)

    Michel, F. C.

    1990-01-01

    The paper concentrates on disks around old extinct pulsars, that can produce gamma-ray bursts owing to viscous evolution of the disk bringing it into the near vicinity of the neutron star, with runaway ionization of the disk and simultaneous precipitation of this plasma onto the neutron star. An old extinct pulsar is modeled as a magnetized neutron star circled by a ring of cold dense matter with an orbital period approximately equal to the rotational period of the neutron star. The numerical estimates produced are found to be consistent with the observed properties of gamma-ray bursters.

  9. Light Dawns on Dark Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    2010-12-01

    Gamma-ray bursts are among the most energetic events in the Universe, but some appear curiously faint in visible light. The biggest study to date of these so-called dark gamma-ray bursts, using the GROND instrument on the 2.2-metre MPG/ESO telescope at La Silla in Chile, has found that these gigantic explosions don't require exotic explanations. Their faintness is now fully explained by a combination of causes, the most important of which is the presence of dust between the Earth and the explosion. Gamma-ray bursts (GRBs), fleeting events that last from less than a second to several minutes, are detected by orbiting observatories that can pick up their high energy radiation. Thirteen years ago, however, astronomers discovered a longer-lasting stream of less energetic radiation coming from these violent outbursts, which can last for weeks or even years after the initial explosion. Astronomers call this the burst's afterglow. While all gamma-ray bursts [1] have afterglows that give off X-rays, only about half of them were found to give off visible light, with the rest remaining mysteriously dark. Some astronomers suspected that these dark afterglows could be examples of a whole new class of gamma-ray bursts, while others thought that they might all be at very great distances. Previous studies had suggested that obscuring dust between the burst and us might also explain why they were so dim. "Studying afterglows is vital to further our understanding of the objects that become gamma-ray bursts and what they tell us about star formation in the early Universe," says the study's lead author Jochen Greiner from the Max-Planck Institute for Extraterrestrial Physics in Garching bei München, Germany. NASA launched the Swift satellite at the end of 2004. From its orbit above the Earth's atmosphere it can detect gamma-ray bursts and immediately relay their positions to other observatories so that the afterglows could be studied. In the new study, astronomers combined Swift

  10. Long-Lag, Wide-pulse Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Currently, the best available probe of the early phase of gamma-ray burst (GRB) jet attributes is the prompt gamma-ray emission, in which several intrinsic and extrinsic variables determine GRB pulse evolution. Bright, usually complex bursts have many narrow pulses that are difficult to model due to overlap. However, the relatively simple, long spectral lag, wide-pulse bursts may have simpler physics and are easier to model. In this work we analyze the temporal and spectral behavior of wide pulses in 24 long-lag bursts, using a pulse model with two shape parameters - width and asymmetry - and the Band spectral model with three shape parameters. We find that pulses in long-lag bursts are distinguished both temporally and spectrally from those in bright bursts: the pulses in long spectral lag bursts are few in number, and approximately 100 times wider (10s of seconds), have systematically lower peaks in vF(v), harder low-energy spectra and softer high-energy spectra. We find that these five pulse descriptors are essentially uncorrelated for our long-lag sample, suggesting that at least approximately 5 parameters are needed to model burst temporal and spectral behavior. However, pulse width is strongly correlated with spectral lag; hence these two parameters may be viewed as mutual surrogates. We infer that accurate formulations for estimating GRB luminosity and total energy will depend on several gamma-ray attributes, at least for long-lag bursts. The prevalence of long-lag bursts near the BATSE trigger threshold, their predominantly low vF(v) spectral peaks, and relatively steep upper power-law spectral indices indicate that Swift will detect many such bursts.

  11. Sensitivity of HAWC to gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Taboada, Ignacio; HAWC Collaboration

    2012-12-01

    HAWC is a ground based very high-energy gamma ray detector under construction in Mexico at an altitude of 4100 m a.s.l. Higher altitude, improved design and a larger physical size used to reject CR background, make HAWC 10-20 times more sensitive than its predecessor Milagro. HAWC's large field of view, ~2sr, and over 90% duty cycle make it ideal to search for GRBs. We review the sensitivity of HAWC to GRBs with two independent data acquisition systems. We show that some of the brightest GRBs observed by Fermi LAT (e.g. GRB 090510) could result in >5 σ observation by HAWC. The observations (or limits) of GRBs by HAWC will provide information on the high-energy spectra of GRBs. The high-energy spectra will teach us about extra galactic background light, the Lorentz boost factor of the jets tha power GRBs and/or particle acceleration models of GRBs. Finally we present limits on > 10 GeV emission from GRB 111016B, recently studied with HAWC's engineering array VAMOS.

  12. Gamma-ray bursts during neutron star formation. Gamma-ray bursts and transient X-ray sources

    NASA Technical Reports Server (NTRS)

    Cohen, J. M.; Desai, U. D.; Holt, S. S.

    1973-01-01

    Discussions are presented of the associations between cosmic gamma ray bursts and transient X-ray sources, and the release of gravitational binding energy during the formation of neutron stars. The model for studying the associations is described along with the release of neutrinos during the collapse of white dwarfs.

  13. Terrestrial Gamma Ray Flash Search in the Triggered Gamma Ray Burst Data of Fermi

    NASA Astrophysics Data System (ADS)

    Hughes, M.; Connaughton, V.

    2012-12-01

    Terrestrial Gamma Ray flashes (TGFs) occur near lightning-producing storms. The Fermi Gamma-Ray Burst monitor (GBM) has a catalog of over 200 TGFs which were found using an on-board algorithm. However, the limitations of the on-board algorithm mean that weaker events are undetected, and in normal data-taking mode (0.256 s resolution) cannot be found in an offline analysis. To get an idea of how many TGFs GBM could be expected to detect in an offline analysis of its highest temporal resolution data, we inspected the high-resolution data available around the times of non-TGF triggers gathered over the four years of the Fermi mission. The triggered data were from nearly 1000 gamma ray bursts observed by GBM. After applying statistical tests to the candidates we uncovered, and rejecting likely cosmic-ray events, 28 TGF candidates remained. Comparing the exposures of the high-resolution data with the time taken to record 28 TGFs on-board, we estimate a 36-fold increase in detected TGFs with the availability of high-resolution data throughout the Fermi orbit.

  14. HUBBLE STAYS ON TRAIL OF FADING GAMMA-RAY BURST FIREBALL

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A Hubble Space Telescope image of the fading fireball from one of the universe's most mysterious phenomena, a gamma-ray burst. Though the visible component has faded to 1/500th its brightness (27.7 magnitude) from the time it was first discovered by ground- based telescopes last March (the actual gamma-ray burst took place on February 28), Hubble continues to clearly see the fireball and discriminated a surrounding nebulosity (at 25th magnitude) which is considered a host galaxy. The continued visibility of the burst, and the rate of its fading, support theories that the light from a gamma-ray burst is an expanding relativistic (moving near the speed of light) fireball, possibly produced by the collision of two dense objects, such as an orbiting pair of neutron stars. If the burst happened nearby, within our own galaxy, the resulting fireball should have had only enough energy to propel it into space for a month. The fact that this fireball is still visible after six months means the explosion was truly titanic and, to match the observed brightness, must have happened at the vast distances of galaxies. The energy released in a burst, which can last from a fraction of a second to a few hundred seconds, is equal to all of the Sun's energy generated over its 10 billion year lifetime. The false-color image was taken Sept. 5, 1997 with the Space Telescope Imaging Spectrograph. Credit: Andrew Fruchter (STScI), Elena Pian (ITSRE-CNR), and NASA

  15. HUBBLE STAYS ON TRAIL OF FADING GAMMA-RAY BURST FIREBALL

    NASA Technical Reports Server (NTRS)

    2002-01-01

    A Hubble Space Telescope image of the fading fireball from one of the universe's most mysterious phenomena, a gamma-ray burst. Though the visible component has faded to 1/500th its brightness (27.7 magnitude) from the time it was first discovered by ground- based telescopes last March (the actual gamma-ray burst took place on February 28), Hubble continues to clearly see the fireball and discriminated a surrounding nebulosity (at 25th magnitude) which is considered a host galaxy. The continued visibility of the burst, and the rate of its fading, support theories that the light from a gamma-ray burst is an expanding relativistic (moving near the speed of light) fireball, possibly produced by the collision of two dense objects, such as an orbiting pair of neutron stars. If the burst happened nearby, within our own galaxy, the resulting fireball should have had only enough energy to propel it into space for a month. The fact that this fireball is still visible after six months means the explosion was truly titanic and, to match the observed brightness, must have happened at the vast distances of galaxies. The energy released in a burst, which can last from a fraction of a second to a few hundred seconds, is equal to all of the Sun's energy generated over its 10 billion year lifetime. The false-color image was taken Sept. 5, 1997 with the Space Telescope Imaging Spectrograph. Credit: Andrew Fruchter (STScI), Elena Pian (ITSRE-CNR), and NASA

  16. Gamma-Ray Burst Intensity Distributions

    NASA Technical Reports Server (NTRS)

    Band, David L.; Norris, Jay P.; Bonnell, Jerry T.

    2004-01-01

    We use the lag-luminosity relation to calculate self-consistently the redshifts, apparent peak bolometric luminosities L(sub B1), and isotropic energies E(sub iso) for a large sample of BATSE bursts. We consider two different forms of the lag-luminosity relation; for both forms the median redshift, for our burst database is 1.6. We model the resulting sample of burst energies with power law and Gaussian dis- tributions, both of which are reasonable models. The power law model has an index of a = 1.76 plus or minus 0.05 (95% confidence) as opposed to the index of a = 2 predicted by the simple universal jet profile model; however, reasonable refinements to this model permit much greater flexibility in reconciling predicted and observed energy distributions.

  17. The First Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    NASA Astrophysics Data System (ADS)

    Briggs, Michael; Connaughton, Valerie; Stanbro, Matthew; Zhang, Binbin; Bhat, Narayana; Fishman, Gerald; Roberts, Oliver; Fitzpatrick, Gerard; McBreen, Shelia; Grove, Eric; Chekhtman, Alexandre

    2015-04-01

    We present summary results from the first catalog of Terrestrial Gamma-ray Flashes (TGFs) detected with the Gamma-ray Burst Monitor (GBM) on the Fermi Space Telescope. The catalog reports parameters for over 2700 TGFs. Since the launch of Fermi in 2008 the TGF detection sensitivity of GBM has been improved several times, both in the flight software and in ground analysis. Starting in 2010 July individual photons were downloaded for portions of the orbits, enabling an off-line search that found weaker and shorter TGFs. Since 2012 November 26 this telemetry mode has been extended to continuous coverage. The TGF sample is reliable, with cosmic rays rejected using data both from Fermi GBM and from the Large Area Telescope on Fermi. The online catalog include times (UTC and solar), spacecraft geographic positions, durations, count intensities and Bayesian Block durations. The catalog includes separate tables for bright TGFs detected by the flight software and for Terrestrial Electron Beams (TEBs).

  18. Stability of fireballs and gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Waxman, Eli; Piran, Tsvi

    1994-01-01

    Fireballs are an essential part of any cosmological gamma-ray burst. We derive a stability criterion for fireballs and show that fireballs are Rayleigh-Taylor unstable in any region in which the entropy decreases outward. The instability begins to operate when the fireball becomes matter dominated. Among the possible implications of the instability are the following: (1) Conversion of a fraction of the radiation energy to a convective energy expressed in the motion of bubbles relative to each other. (2) Penetration of fast bubbles through slower ones and creation of high-gamma regimes which are essential for efficient conversion of the energy to gamma-rays. (3) Formation of rapid time variation (of the scale of the bubbles) in the observed gamma-rays.

  19. MAGIC Telescope Observations of Gamma-Ray Bursts

    SciTech Connect

    Garczarczyk, M.; Becerra-Gonzalez, J.; Gaug, M.; Antonelli, A.; Carosi, A.; La Barbera, A.; Spiro, S.; Bastieri, D.; Covino, S.; Dominguez, A.; Longo, F.; Scapin, V.

    2010-10-15

    MAGIC is built to perform observations of prompt and early afterglow emission from Gamma-Ray Bursts (GRBs) above 25 GeV. The instrument is designed to have the lowest possible energy threshold among the ground based {gamma}-ray detectors and the fastest reaction time to alerts distributed over the GRB Coordinates Network (GCN). The MAGIC-I telescope observed 57 GRBs during the first six years. In no cases Very High Energy (VHE){gamma}-ray emission above the threshold energy could be detected. The telescope has undergone several major improvements in sensitivity and repositioning performance. The biggest improvement in sensitivity was achieved with the installation of the second MAGIC-II telescope. Since more than one year both telescopes are observing in stereo mode. MAGIC are the only telescopes fast and sensitive enough to extend the observational energy range of satellite detectors, while GRB prompt and early afterglow emission is still ongoing.

  20. Analysis of the Swift Gamma-Ray Bursts duration

    SciTech Connect

    Horvath, I.; Veres, P.; Balazs, L. G.; Kelemen, J.; Bagoly, Z.

    2008-10-22

    Two classes of gamma-ray bursts have been identified in the BATSE catalogs characterized by durations shorter and longer than about 2 seconds. There are, however, some indications for the existence of a third type of burst. Swift satellite detectors have different spectral sensitivity than pre-Swift ones for gamma-ray bursts. Therefore it is worth to reanalyze the durations and their distribution and also the classification of GRBs. Using The First BAT Catalog the maximum likelihood estimation was used to analyzed the duration distribution of GRBs. The three log-normal fit is significantly (99.54% probability) better than the two for the duration distribution. Monte-Carlo simulations also confirm this probability (99.2%)

  1. DMSP satellite detections of gamma-ray bursts

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R. W.; Griffee, J. W.

    1996-08-01

    Gamma-ray burst detectors are aboard six U.S. Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, two of which are currently in use. Their 800-km altitude orbits give a field of view to 117 deg. from the zenith. A great many bursts have been detected, usually in coincidence with detections by GRO or other satellites such as PVO or ULYSSES. The directions of the sources can be determined with considerable accuracy from such correlated observations, even when GRO/BATSE with its directional capabilities is not involved. Thus these DMSP data, especially in conjunction with other observations, should be helpful in trying to understand the true nature of gamma-ray bursts.

  2. DMSP satellite detections of gamma-ray bursts

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R.W.; Griffee, J.W.

    1996-08-01

    Gamma-ray burst detectors are aboard six U.S. Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, two of which are currently in use. Their 800-km altitude orbits give a field of view to 117{degree} from the zenith. A great many bursts have been detected, usually in coincidence with detections by GRO or other satellites such as PVO or ULYSSES. The directions of the sources can be determined with considerable accuracy from such correlated observations, even when GRO/BATSE with its directional capabilities is not involved. Thus these DMSP data, especially in conjunction with other observations, should be helpful in trying to understand the true nature of gamma-ray bursts. {copyright} {ital 1996 American Institute of Physics.}

  3. Gamma-ray bursts from remnant neutron star disks

    NASA Technical Reports Server (NTRS)

    Michel, F. C.

    1985-01-01

    The consequences of a disk of matter orbiting an old neutron star are examined. When the inner edge of the disk approaches close to the star, due to internal viscous drag, runaway ionization of the disk occurs and the resulting plasma is precipitated to the surface of the neutron star, thereby producing a gamma-ray burst. Rough numerical estimates of the occurrence rate are given and found to be consistent with gamma-ray burst observations. The estimates indicate that energies of 10 to the 39th ergs or more could be released with rise times as fast as 0.3 ms. Consideration is given to explanations of the March 5, 1979 event (Cline et al., 1980). Some possible observational searches for optical or IR emission from such disks at the locations of known burst sources and pulsars are discussed.

  4. Gamma-ray bursts and neutron star field decay

    NASA Technical Reports Server (NTRS)

    Hartmann, Dieter; Blumenthal, George; Chuang, Kuan-Wen; Hurley, Kevin; Kargatis, Vincent; Liang, Edison; Linder, Eric

    1992-01-01

    Assuming a Galactic origin of gamma-ray bursts, we use pulsar data to calculate the spatial distribution of neutron stars and determine the sampling depths of current detectors. Based on these distance limits, we calculate the corresponding age distribution of Galactic neutron stars and apply an exponential field decay model to test whether the observed high incidence rate of cyclotron lines is consistent with suggested field decay time scales of order 10 exp 7 years. We find that the properties of the observed population of gamma-ray bursts are inconsistent with the idea that bursts originate at arbitrary times on neutron stars whose fields decay on time scales shorter than about 10 exp 9 years. Possible interpretations of this inconsistency are discussed.

  5. Gravitational lensing, time delay, and gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Mao, Shude

    1992-01-01

    The probability distributions of time delay in gravitational lensing by point masses and isolated galaxies (modeled as singular isothermal spheres) are studied. For point lenses (all with the same mass) the probability distribution is broad, and with a peak at delta(t) of about 50 S; for singular isothermal spheres, the probability distribution is a rapidly decreasing function with increasing time delay, with a median delta(t) equals about 1/h month, and its behavior depends sensitively on the luminosity function of galaxies. The present simplified calculation is particularly relevant to the gamma-ray bursts if they are of cosmological origin. The frequency of 'recurrent' bursts due to gravitational lensing by galaxies is probably between 0.05 and 0.4 percent. Gravitational lensing can be used as a test of the cosmological origin of gamma-ray bursts.

  6. DMSP satellite detections of gamma-ray bursts

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R.W.

    1995-12-31

    Gamma-ray burst detectors are aboard six U. S. Air Force defense Meteorological Satellite Program (DMSP) spacecraft, two of which are currently in use. Their 800-km altitude orbits give a field of view to 117 degrees from the zenith. A great many bursts have been detected, usually in coincidence with detections by GRO or other satellites such as PVO or ULYSSES. The directions of the sources can be determined with considerable accuracy from such correlated observations, even when GRO/BATSE with its directional capabilities is not involved. Thus these DMSP data, especially in conjunction with other observations, should be helpful in trying to understand the true nature of gamma-ray bursts. 8 refs., 5 figs.

  7. DMSP satellite detections of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Terrell, J.; Lee, P.; Klebesadel, R. W.

    1995-01-01

    Gamma-ray burst detectors are aboard six U. S. Air Force defense Meteorological Satellite Program (DMSP) spacecraft, two of which are currently in use. Their 800-km altitude orbits give a field of view to 117 degrees from the zenith. A great many bursts have been detected, usually in coincidence with detections by GRO or other satellites such as PVO or ULYSSES. The directions of the sources can be determined with considerable accuracy from such correlated observations, even when GRO/BATSE with its directional capabilities is not involved. Thus these DMSP data, especially in conjunction with other observations, should be helpful in trying to understand the true nature of gamma-ray bursts.

  8. A cosmic gamma-ray burst on May 14, 1975

    NASA Technical Reports Server (NTRS)

    Herzo, D.; Dayton, B.; Zych, A. D.; White, R. S.

    1975-01-01

    A cosmic gamma-ray burst is reported that occurred at 29309.11 s UTC, May 14, 1975. The burst was detected at an atmospheric depth of 4 g/sq cm residual atmosphere with the University of California double scatter gamma-ray telescope launched on a balloon from Palestine, Texas at 1150 UTC, May 13, 1975. The burst was observed both in the single scatter mode by the top liquid scintillator tank in anti-coincidence with the surrounding plastic scintillator and in the double scatter mode from which energy and directional information are obtained. The burst is 24 standard deviations above the background for single scatter events. The total gamma-ray flux in the burst, incident on the atmosphere with photon energy greater than 0.5 MeV, is 0.59 + or - 0.15 photons/sq cm. The initial rise time to 90% of maximum is 0.015 + or - 0.005 s and the duration is 0.11 s. Time structure down to the 5 ms resolution of the telescope is seen. The mean flux over this time period is 5.0 + or - 1.3 photons/sq cm/s and the maximum flux is 8.5 + or - 2.1 photons/sq cm/s.

  9. Gamma-Ray Burst Precursor Activity as Observed with BATSE

    NASA Technical Reports Server (NTRS)

    Koshut, Thomas M.; Kouveliotou, Chryssa; Paciesas, William S.; vanParadijs, Jan; Pendleton, Geoffrey N.; Briggs, Michael S.; Fishman, Gerald J.; Meegan, Charles A.

    1995-01-01

    Gamma-ray burst time histories often consist of multiple episodes of emission with the count rate dropping to the background level between adjacent episodes. We define precursor activity as any case in which the first episode (referred to as the precursor episode) has a lower peak intensity than that of the remaining emission (referred to as the main episode) and is separated from the remaining burst emission by a background interval that is at least as long as the remaining emission. We find that approx. 3% of the bursts observed with the Burst and Transient Source Experiment (BATSE) on Compton Gamma Ray Observatory (CGRO) satisfy this definition. We present the results of a study of the properties of these events. The spatial distribution of these sources is consistent with that of the larger set of all BATSE gamma-ray bursts: inhomogeneous and isotropic. A correlation between the duration of the precursor emission and the duration of the main episode emission is observed at about the 3 sigma confidence level. We find no meaningful significant correlations between or among any of the other characteristics of the precursor or main episode emission. It appears that the characteristics of the main episode emission are independent of the existence of the precursor emission.

  10. Central Engine Memory of Gamma-Ray Bursts and Soft Gamma-Ray Repeaters

    NASA Astrophysics Data System (ADS)

    Zhang, Bin-Bin; Zhang, Bing; Castro-Tirado, Alberto J.

    2016-04-01

    Gamma-ray bursts (GRBs) are bursts of γ-rays generated from relativistic jets launched from catastrophic events such as massive star core collapse or binary compact star coalescence. Previous studies suggested that GRB emission is erratic, with no noticeable memory in the central engine. Here we report a discovery that similar light curve patterns exist within individual bursts for at least some GRBs. Applying the Dynamic Time Warping method, we show that similarity of light curve patterns between pulses of a single burst or between the light curves of a GRB and its X-ray flare can be identified. This suggests that the central engine of at least some GRBs carries “memory” of its activities. We also show that the same technique can identify memory-like emission episodes in the flaring emission in soft gamma-ray repeaters (SGRs), which are believed to be Galactic, highly magnetized neutron stars named magnetars. Such a phenomenon challenges the standard black hole central engine models for GRBs, and suggest a common physical mechanism behind GRBs and SGRs, which points toward a magnetar central engine of GRBs.

  11. CENTRAL ENGINE MEMORY OF GAMMA-RAY BURSTS AND SOFT GAMMA-RAY REPEATERS

    SciTech Connect

    Zhang, Bin-Bin; Castro-Tirado, Alberto J.; Zhang, Bing

    2016-04-01

    Gamma-ray bursts (GRBs) are bursts of γ-rays generated from relativistic jets launched from catastrophic events such as massive star core collapse or binary compact star coalescence. Previous studies suggested that GRB emission is erratic, with no noticeable memory in the central engine. Here we report a discovery that similar light curve patterns exist within individual bursts for at least some GRBs. Applying the Dynamic Time Warping method, we show that similarity of light curve patterns between pulses of a single burst or between the light curves of a GRB and its X-ray flare can be identified. This suggests that the central engine of at least some GRBs carries “memory” of its activities. We also show that the same technique can identify memory-like emission episodes in the flaring emission in soft gamma-ray repeaters (SGRs), which are believed to be Galactic, highly magnetized neutron stars named magnetars. Such a phenomenon challenges the standard black hole central engine models for GRBs, and suggest a common physical mechanism behind GRBs and SGRs, which points toward a magnetar central engine of GRBs.

  12. Simultaneous Observations of Compton Gamma Ray Observatory-BATSE Gamma-Ray Bursts with the COBE DMR

    NASA Astrophysics Data System (ADS)

    Jackson, Peter D.; Winkler, Christoph; Stacy, J. Gregory; Bontekoe, Tj. Romke

    1998-09-01

    Data acquired with the COBE Differential Microwave Radiometer (DMR) provide a unique opportunity to observe simultaneous emission from cosmic gamma-ray bursts in the previously unexplored microwave region of the spectrum. We have searched the COBE DMR time-ordered data sets for instances when one of the DMR horns (FWHM ~ 7°) was pointing in the direction of a gamma-ray burst at the time of burst occurrence. During the overlap period 1991 April-December corresponding to the first public release of COBE data, 210 Compton Gamma Ray Observatory (CGRO)/BATSE gamma-ray bursts listed in the Third BATSE (3B) Catalog were viewable by the COBE DMR. For five of these events the DMR was pointing within 7° of the burst positions at the exact moment of burst occurrence. For another four events the DMR was pointed within 2° of the BATSE positions within 10 s of the burst trigger time. No obvious microwave emission (at 31.5, 53, or 90 GHz), with upper limits in the 10-100 kJy range, can be associated with any of these events. The COBE DMR has a relatively low sensitivity for the detection of point sources within its field of view. A positive detection of a gamma-ray burst by the COBE DMR would imply that the integrated microwave flux must be of the same order as the energy observed in gamma rays. By extending an acceptance window in time of up to 20 minutes before and after a gamma-ray burst another 60 bursts are sampled by the DMR, whose signals are analyzed statistically. We conclude that the ``average'' gamma-ray burst produces less than about 7-42 kJy in simultaneous microwave radiation.

  13. SVOM: a new mission for Gamma-Ray Bursts studies

    NASA Astrophysics Data System (ADS)

    Götz, Diego; SVOM Collaboration

    The French Space Agency (CNES) in collaboration with the Chinese National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS) are developing a new mission aiming at studying Gamma-Ray Bursts (GRBs) called SVOM (Space-based multi-band astronomical Variable Objects Monitor). The mission will consist of a set of space borne instruments and a set of ground based ones. The space borne instruments include two wide field of view gamma-ray instruments, and two narrow field ones operating in the X-ray and visible domains. The two gamma-ray instruments are a coded mask soft-gamma ray imager (4-250 keV), ECLAIRs, with a 2 sr field of view, which detects and localizes in real time GRB candidates, and a gamma-ray spectrometer (50 keV-5 MeV), GRM, with the same field of view as ECLAIRs, but without imaging capabilities. The narrow field instruments, used after an autonomous satellite slew for fine localization and afterglow studies, are MXT (0.2-10 keV) and VT (400-950 nm). The space borne instruments are complemented on ground by two dedicated robotic telescopes (GFTs), designed for position refinement and early afterglow studies, and a set of ground wide angle cameras (GWACs) that aim at monitoring the field of view of ECLAIRs with the goal of detecting the prompt optical emission of GRBs.

  14. Celestial Gamma Ray Bursts Detector Development and Model Simulations

    NASA Astrophysics Data System (ADS)

    Mock, Patrick Charles

    1993-12-01

    Celestial gamma-ray bursts are a poorly understood astrophysical phenomenon. These transient events were discovered over twenty years ago, yet their origin is still an unsolved mystery. At present no quiescent counterpart to a gamma ray burst source has been conclusively identified, partly because the poor angular resolution of gamma ray detectors and the short durations of the bursts make it difficult to determine precise source positions. (A few precise source positions have been determined by analysis of burst arrival times at widely separated detectors.) The High Energy Transient Experiment (HETE), described by Ricker, et al. (1992), is a new gamma ray astronomy satellite designed to overcome these difficulties. It can determine precise source positions by simultaneously observing a gamma ray burst with gamma ray x-ray, and ultraviolet (UV) instruments and utilizing the better angular resolutions available with the x-ray and UV instruments. In the first part of this dissertation I present experimental research which contributes to the development of a UV-sensitive solid-state imaging detector for the HETE satellite. The detector is a thinned, backside-illuminated charge-coupled device (CCD). The UV quantum efficiency (QE) is very sensitive to the results of the back-surface treatment, which stabilizes and protects that surface. As part of the detector development I designed and built an instrument to measure the quantum efficiency of a CCD over the wavelength range of 200--500~nm. With this instrument I measured the QE of seven prototype devices that were manufactured with three different back-surface technologies. I derived a statistical test to measure the mean number of electrons per photon, which increases from unity with increasing photon energy above a threshold of ~3.65~eV (340 nm). This effect is critically important when making photometric measurements at these wavelengths with solid state detectors. I also developed a simple physically-motivated model

  15. Gravitational waves versus X-ray and gamma-ray emission in a short gamma-ray burst

    SciTech Connect

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, R. E-mail: jorge.rueda@icra.it

    2014-06-01

    Recent progress in the understanding of the physical nature of neutron star equilibrium configurations and the first observational evidence of a genuinely short gamma-ray burst (GRB), GRB 090227B, allows us to give an estimate of the gravitational waves versus the X-ray and gamma-ray emission in a short GRB.

  16. Unthermalized positrons in gamma ray burst sources

    NASA Technical Reports Server (NTRS)

    Tkaczyk, W.; Karakula, S.

    1992-01-01

    The spectra of the broadening 0.511 MeV annihilation line produced by high temperatures was calculated in the case of unthermalized plasma; i.e., T sub e(+) is not = T sub e(-). The flattening in the spectrum of the annihilation lines for large differences of electron and positron temperatures is a strong indication that the observed features of the hard tailed spectrum of the gamma bursts can be well described by annihilation of unthermalized positrons. It is proposed that the charge separation occurring in Eddington limited accretion onto a neutron star or the one photon pair production in strong magnetic fields as a mechanism for the production of unthermalized positrons in the sources of gamma bursts. From the best fit of experimental spectra by the model, the parameters of sources for which the regions with different plasma temperatures can exist is evaluated.

  17. Did A Galactic Gamma-Ray Burst Kill the Dinosaurs?

    NASA Astrophysics Data System (ADS)

    Brecher, K.

    1997-12-01

    Gamma-ray bursts now appear to be primarily of extragalactic origin. Statistically, assuming isotropic emission, the observed event rates and fluxes imply that one event occurs per 10(4) \\ - 10(6) \\ years per galaxy, with about 10(51) \\ - 10(53) \\ ergs in gamma-rays emitted per event. Unless the Milky Way is unusual, a gamma-ray burst should occur within 10(2) \\ - 10(3) \\ pc of the Sun in a time span of order 10(8) \\ years. Independent of the underlying cause of the event, it would irradiate the solar system with a brief flash of MeV gamma-rays with a fluence as large as 10(9) - 10(11) \\ erg cm(-2) . What is the effect of such an event on the Earth and objects nearby? Ruderman (\\underbar{Science}, 184, 1079, 1974) and subsequent authors have considered a number of effects of a flash of gamma-rays from a nearby supernova explosion on the Earth's atmosphere, and on its biota. However, with regard to the demise of the dinosaurs, it appears that there was a marked increase in the deposition rate of the rare earth iridium coincident with their extinction. For this reason, an asteroid-Earth impact has been considered the leading contender for the death of the dinosaurs. Here we consider a new mechanism for mass biological extinctions, caused by small comets nudged into the inner solar system by nearby gamma-ray bursts. If comets populate the Oort cloud with a wide distribution of masses, radii and orbital eccentricities, we find that small (< 1 km), low density (10(-2) \\ gm cm(-3) ) objects in highly eccentric orbits can be injected into the inner solar system by a nearby gamma-ray burst. For a relatively brief period of time, the near Earth comet population would increase dramatically. The consequent increased probability of comet-Earth impacts of appropriate energy and material content could account for many of the characteristics of the Cretaceous-Tertiary or other terrestrial mass biological extinctions.

  18. The Locations of Gamma-Ray Bursts Measured by Comptel

    NASA Technical Reports Server (NTRS)

    Kippen, R. Marc; Ryan, James M.; Connors, Alanna; Hartmann, Dieter H.; Winkler, Christoph; Kuiper, Lucien; Varendorff, Martin; McConnell, Mark L.; Hurley, Kevin; Hermsen, Wim; hide

    1998-01-01

    The COMPTEL instrument on the Compton Gamma Ray Observatory is used to measure the locations of gamma-ray bursts through direct imaging of MeV photons. In a comprehensive search, we have detected and localized 29 bursts observed between 1991 April 19 and 1995 May 31. The average location accuracy of these events is 1.25 deg (1 sigma), including a systematic error of approx. 0.5 deg, which is verified through comparison with Interplanetary Network (IPN) timing annuli. The combination of COMPTEL and IPN measurements results in locations for 26 of the bursts with an average "error box" area of only approx. 0.3 deg (1 sigma). We find that the angular distribution of COMPTEL burst locations is consistent with large-scale isotropy and that there is no statistically significant evidence of small-angle autocorrelations. We conclude that there is no compelling evidence for burst repetition since no more than two of the events (or approx. 7% of the 29 bursts) could possibly have come from the same source. We also find that there is no significant correlation between the burst locations and either Abell clusters of galaxies or radio-quiet quasars. Agreement between individual COMPTEL locations and IPN annuli places a lower limit of approx. 100 AU (95% confidence) on the distance to the stronger bursts.

  19. GRO: Black hole models for gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Shaham, Jacob

    1994-01-01

    The possibility of creating gamma ray bursts (GRB's) from accretion flows on to black holes is investigated. The mechanism of initial energy release in the form of a burst is not understood yet. The typical time scales involved in this energy release and the initial distribution of photons as a function of energy are studied. As a first step the problem is formulated in the Minkowski spacetime for a homogeneous and isotropic burst. For an arbitrary initial distribution of photons, the equations of relativistic kinetic theory are formulated for nonequilibrium plasmas which can take into account various particle creation and annihilation processes and various scattering processes.

  20. The First FERMI-LAT Gamma-Ray Burst Catalog

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; hide

    2013-01-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy great than (20 MeV) gamma-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above approximately 20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  1. The First FERMI-LAT Gamma-Ray Burst Catalog

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bhat, P. N.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Burgess, J. Michael; Buson, S.; Byrne, D.; Caliandro, G. A.; Ferrara, E. C.; Gehrels, N.; Guiriec, S.; McEnery, J. E.; Nemmen, R.; Perkins, J. S.; Racusin, J. L.; Thompson, D. J.; Kouveliotou, C.

    2013-01-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy great than (20 MeV) gamma-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above approximately 20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  2. Gamma Ray Burst 150518a measured at different wavelengths

    NASA Astrophysics Data System (ADS)

    Apala, Ellizabeth Ann; Soderberg, Alicia Margarita; West, Michael

    2016-01-01

    Gamma Ray Burst (GRB's), extremely energetic flashes of Gamma Rays, are caused by either deaths of massive unstable stars or colliding binary neutron stars. A unique burst, GRB 150518a, had two recorded bursts fifteen minutes apart which is very rare and is considered to be ultra-long, lasting around thirty minutes total and is associated with a Supernova explosion. GBR 150518a is also extremely close compared to the average burst being measured to have a redshift of .2, this is important to note because GRB's measuring less than a redshift of .3 only are seen every ten years. Gamma rays are emitted by supernovae, neutron stars, black holes, and quasars and by studying GRB's it allows us to see more deeply into how these objects function. The first few days of GRB 150518as' detected afterglow was plotted in different wavelengths, including optical, x-ray, radio, and infrared, in flux verses time. Data is continuously being added as time goes on. This research is funded by the NSF, grant number 1358990.

  3. VERITAS OBSERVATIONS OF GAMMA-RAY BURSTS DETECTED BY SWIFT

    SciTech Connect

    Acciari, V. A.; Benbow, W.; Aliu, E.; Errando, M.; Arlen, T.; Aune, T.; Beilicke, M.; Buckley, J. H.; Bugaev, V.; Bradbury, S. M.; Byrum, K.; Cannon, A.; Collins-Hughes, E.; Cesarini, A.; Connolly, M. P.; Christiansen, J. L.; Ciupik, L.; Cui, W.; Duke, C.; Falcone, A.; and others

    2011-12-10

    We present the results of 16 Swift-triggered Gamma-ray burst (GRB) follow-up observations taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) telescope array from 2007 January to 2009 June. The median energy threshold and response time of these observations were 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter timescale determined by the maximum VERITAS sensitivity to a burst with a t{sup -1.5} time profile. This temporal model is characteristic of GRB afterglows with high-energy, long-lived emission that have been detected by the Large Area Telescope on board the Fermi satellite. No significant very high energy (VHE) gamma-ray emission was detected and upper limits above the VERITAS threshold energy are calculated. The VERITAS upper limits are corrected for gamma-ray extinction by the extragalactic background light and interpreted in the context of the keV emission detected by Swift. For some bursts the VHE emission must have less power than the keV emission, placing constraints on inverse Compton models of VHE emission.

  4. 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.

  5. VERY HIGH ENERGY gamma-RAY AFTERGLOW EMISSION OF NEARBY GAMMA-RAY BURSTS

    SciTech Connect

    Xue, R. R.; Fan, Y. Z.; Wei, D. M.; Tam, P. H.; Wagner, S. J.; Behera, B. E-mail: phtam@lsw.uni-heidelberg.d

    2009-09-20

    The synchrotron self-Compton (SSC) emission from gamma-ray burst (GRB) forward shock can extend to the very high energy (VHE; E{sub {gamma}} > 100 GeV) range. Such high energy photons are rare and are attenuated by the cosmic infrared background before reaching us. In this work, we discuss the prospect to detect these VHE photons using the current ground-based Cherenkov detectors. Our calculated results are consistent with the upper limits obtained with several Cherenkov detectors for GRB 030329, GRB 050509B, and GRB 060505 during the afterglow phase. For five bursts in our nearby GRB sample (except for GRB 030329), current ground-based Cherenkov detectors would not be expected to detect the modeled VHE signal. Only for those very bright and nearby bursts like GRB 030329, detection of VHE photons is possible under favorable observing conditions and a delayed observation time of {approx}<10 hr.

  6. Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2004-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

  7. Swift Gamma-ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2005-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UT, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

  8. Precursors of Short Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Troja, E.; Rosswog, S.; Gehrels, N.

    2010-01-01

    We carried out a systematic search of precursors on the sample of short GRBs observed by Swift. We found that approx. 8-10% of short GRBs display such early episode of emission. One burst (GRB 090510) shows two precursor events, the former approx.13 s and the latter approx. 0.5 s before the GRB. We did not find any substantial difference between the precursor and the main GRB emission, and between short GRBs with and without precursors. We discuss possible mechanisms to reproduce the observed precursor emission within the scenario of compact object mergers. The implications of our results on quantum gravity constraints are also discussed.

  9. The Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    NASA Astrophysics Data System (ADS)

    Stanbro, M.; Briggs, M. S.; Roberts, O.; McBreen, S.; Bhat, N.; Fitzpatrick, G.

    2015-12-01

    We present results from the catalog of Terrestrial Gamma-ray Flashes (TGFs) detected with the Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope. The first release, in January 2015, provided data on 2700 TGFs. Updates are extending the catalog at a rate of ~800 TGFs per year. The TGF sample is reliable, with cosmic rays rejected using data both from Fermi GBM and from the Large Area Telescope on Fermi. The online catalog include times (UTC and solar), spacecraft geographic positions, durations, count intensities and other Bayesian Block durations. The catalog includes separate tables for bright TGFs detected by the flight software and for Terrestrial Electron Beams (TEBs). In January 2016 additional data will be released online from correlating these TGFs with sferics detected by the World Wide Lightning Location Network (WWLLN). Maps of sferics in the vicinity of each TGF will be provided, as will the locations and times of sferics found to be associated with TGFs.

  10. High Energy Gamma-Ray Emission from Gamma-Ray Bursts - Before GLAST

    SciTech Connect

    Fan, Yi-Zhong; Piran, Tsvi

    2011-11-29

    Gamma-ray bursts (GRBs) are short and intense emission of soft {gamma}-rays, which have fascinated astronomers and astrophysicists since their unexpected discovery in 1960s. The X-ray/optical/radio afterglow observations confirm the cosmological origin of GRBs, support the fireball model, and imply a long-activity of the central engine. The high-energy {gamma}-ray emission (> 20 MeV) from GRBs is particularly important because they shed some lights on the radiation mechanisms and can help us to constrain the physical processes giving rise to the early afterglows. In this work, we review observational and theoretical studies of the high-energy emission from GRBs. Special attention is given to the expected high-energy emission signatures accompanying the canonical early-time X-ray afterglow that was observed by the Swift X-ray Telescope. We also discuss the detection prospect of the upcoming GLAST satellite and the current ground-based Cerenkov detectors.

  11. An iron absorption model of gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.; Kargatis, Vincent E.

    1994-01-01

    Most gamma-ray bursts (GRBs) exhibit deficits of X-rays below approximately 200 keV. Here we consider a spectral model in which the burst source is shielded by an optically thick layer of circumburster material (CBM) rich in iron-group elements whose photoelectric absorption opacity exceeds the Thomson opacity below approximately 120 keV. For power-law distributions of absorption depths along the lines of sight the absorbed spectrum can indeed mimic the typial GRB spectrum. This model predicts that (a) the spectrum should evolve monotonically from hard to soft during each energy release, which is observed in most bursts, especially in fast rise exponential decay bursts; (b) Fe spectral features near 7 keV may be present in some bursts; and (c) the ratio of burst distances to the CBM and to Earth should be approximately 10(exp -11) if the spectral evolution is purely due to Fe stripping by the photons.

  12. Observations of cosmic gamma ray bursts with WATCH on EURECA

    NASA Astrophysics Data System (ADS)

    Brandt, S.; Lund, N.; Castro-Tirado, A. J.

    19 Cosmic Gamma-Ray Bursts were detected by the Wide Angle Telescope for Cosmic Hard X-rays (WATCH) instruments during the 11 months flight of the European Retrievable Carrier (EURECA). The identification of the bursts was complicated by a high frequency of background of events caused by a high energy cosmic ray interactions in the detector and by low energy, trapped particle streams. These background events may simulate the count rate increases characteristic of cosmic gamma bursts. For 12 of the detected events, their true cosmic nature have been confirmed through consistent localizations of the burst sources based on several independent WATCH data sets. The derived positions of the bursts are reported. Additionally, most of the events have been confirmed by coincident detections with instruments on other spacecraft. The features of two of the bursts and the results of searches for related events in the optical are described.

  13. ESA's Integral detects closest cosmic gamma-ray burst

    NASA Astrophysics Data System (ADS)

    2004-08-01

    5 August 2004 A gamma-ray burst detected by ESA's Integral gamma-ray observatory on 3 December 2003 has been thoroughly studied for months by an armada of space and ground-based observatories. Astronomers have now concluded that this event, called GRB 031203, is the closest cosmic gamma-ray burst on record, but also the faintest. This also suggests that an entire population of sub-energetic gamma-ray bursts has so far gone unnoticed... Gamma ray burst model hi-res Size hi-res: 22 KB Credits: CXC/M. Weiss Artist impression of a low-energy gamma-ray burst This illustration describes a model for a gamma-ray burst, like the one detected by Integral on 3 December 2003 (GRB 031203). A jet of high-energy particles from a rapidly rotating black hole interacts with surrounding matter. Observations with Integral on 3 December 2003 and data on its afterglow, collected afterwards with XMM-Newton, Chandra and the Very Large Array telescope, show that GRB 031203 radiated only a fraction of the energy of normal gamma-ray bursts. Like supernovae, gamma-ray bursts are thought to be produced by the collapse of the core of a massive star. However, while the process leading to supernovae is relatively well understood, astronomers still do not know what happens when a core collapses to form a black hole. The discovery of 'under-energetic' gamma-ray bursts, like GRB 031203, should provide valuable clues as to links between supernovae, black holes and gamma-ray bursts. Lo-res JPG (22 Kb) Hi-res TIFF (5800 Kb) Cosmic gamma-ray bursts (GRBs) are flashes of gamma rays that can last from less than a second to a few minutes and occur at random positions in the sky. A large fraction of them is thought to result when a black hole is created from a dying star in a distant galaxy. Astronomers believe that a hot disc surrounding the black hole, made of gas and matter falling onto it, somehow emits an energetic beam parallel to the axis of rotation. According to the simplest picture, all GRBs

  14. Gamma Ray Bursts and Their Links With Supernovae and Cosmology

    NASA Technical Reports Server (NTRS)

    Meszaros, Peter; Gehrels, Neil

    2012-01-01

    Gamma-ray bursts are the most luminous explosions in the Universe, whose origin and mechanism is the focus of intense interest. They appear connected to supernova remnants from massive stars or the merger of their remnants, and their brightness makes them temporarily detectable out to the largest distances yet explored in the Universe. After pioneering breakthroughs from space and ground experiments, their study is entering a new phase with observations from the recently launched Fermi satellite, as well as the prospect of detections or limits from large neutrino and gravitational wave detectors. The interplay between such observations and theoretical models of gamma-ray bursts is reviewed, as well as their connections to supernovae and cosmology.

  15. Classifying gamma-ray bursts with Gaussian Mixture Model

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Bin; Yang, En-Bo; Choi, Chul-Sung; Chang, Heon-Young

    2016-11-01

    Using Gaussian Mixture Model (GMM) and expectation-maximization algorithm, we perform an analysis of time duration (T90) for Compton Gamma Ray Observatory (CGRO)/BATSE, Swift/BAT and Fermi/GBM gamma-ray bursts (GRBs). The T90 distributions of 298 redshift-known Swift/BAT GRBs have also been studied in both observer and rest frames. Bayesian information criterion has been used to compare between different GMM models. We find that two Gaussian components are better to describe the CGRO/BATSE and Fermi/GBM GRBs in the observer frame. Also, we caution that two groups are expected for the Swift/BAT bursts in the rest frame, which is consistent with some previous results. However, Swift GRBs in the observer frame seem to show a trimodal distribution, of which the superficial intermediate class may result from the selection effect of Swift/BAT.

  16. Cosmological Distance Scale to Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Azzam, W. J.; Linder, E. V.; Petrosian, V.

    1993-05-01

    The source counts or the so-called log N -- log S relations are the primary data that constrain the spatial distribution of sources with unknown distances, such as gamma-ray bursts. In order to test galactic, halo, and cosmological models for gamma-ray bursts we compare theoretical characteristics of the log N -- log S relations to those obtained from data gathered by the BATSE instrument on board the Compton Observatory (GRO) and other instruments. We use a new and statistically correct method, that takes proper account of the variable nature of the triggering threshold, to analyze the data. Constraints on models obtained by this comparison will be presented. This work is supported by NASA grants NAGW 2290, NAG5 2036, and NAG5 1578.

  17. High-energy emission in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Matz, S. M.; Forrest, D. J.; Vestrand, W. T.; Chupp, E. L.; Share, G. H.; Rieger, E.

    1985-01-01

    Between February 1980 and August 1983 the Gamma-Ray Spectrometer on the Solar Maximum Mission Satellite (SMM) detected 72 events identified as being of cosmic origin. These events are an essentially unbiased subset of all gamma-ray bursts. The measured spectra of these events show that high energy (greater than 1 MeV) emission is a common and energetically important feature. There is no evidence for a general high-energy cut-off or a distribution of cut-offs below about 6 MeV. These observations imply a limit on the preferential beaming of high energy emission. This constraint, combined with the assumption of isotropic low energy emission, implies that the typical magnetic field strength at burst radiation sites is less than 1 x 10 to the 12th gauss.

  18. Gamma-ray bursts: black holes shining brightly?

    NASA Astrophysics Data System (ADS)

    Wijers, Ralph

    2003-04-01

    Gamma-ray bursts are an archetypical example of serendipity in science: nobody predicted them, asked for them, or was looking for them when nuclear test-ban treaty verification satellites stumbled on them. Since then, they have become one of the big intriguing mysteries of physics, and in the past five years, a boom business of high-energy astrophysics. After briefly recalling the history of the field, I will discuss the recent evidence that gamma-ray bursts are associated with the birth of black holes from massive stars. The enormous energy generation of these biggest blasts in the Universe makes them into powerful labs for the study of extreme physics. In addition, due to their enormous brightness, GRBs may provide us with a tool to study the early Universe. "Sometimes man stumbles on the truth. But usually he just picks himself up and plods on." --- Winston Churchill

  19. Neutron starquakes and the nature of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Madau, P.; Blaes, O.; Blandford, R. D.; Goldreich, P.

    1989-01-01

    The possibility that gamma-ray bursts originate from quakes deep in the solid crust of a neutron star is investigated. Seismic waves are radiated if shear stress is relieved by brittle fracture. However they cannot propagate directly to the surface but are temporarily trapped below a reflecting layer. The shaking of the stellar surface couples the seismic waves to Alfven waves which propagate out into the magnetosphere. The crust-magnetosphere transmission coefficient strongly increases with wave frequency and magnetic field strength. Alfven wave luminosities sufficient to power galactic gamma-ray bursts are possible if magnetic fields greater than 100 billion G cover at least part of the stellar surface. As the Alfven waves propagate out into the low density magnetosphere, they become increasingly charge starved, thereby accelerating particles to relativistic energies.

  20. THE BATSE 5B GAMMA-RAY BURST SPECTRAL CATALOG

    SciTech Connect

    Goldstein, Adam; Preece, Robert D.; Briggs, Michael S.; Burgess, J. Michael; Mallozzi, Robert S.; Fishman, Gerald J.; Kouveliotou, Chryssa

    2013-10-01

    We present systematic spectral analyses of gamma-ray bursts (GRBs) detected with the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory during its entire nine years of operation. This catalog contains two types of spectra extracted from 2145 GRBs, and fitted with five different spectral models resulting in a compendium of over 19,000 spectra. The models were selected based on their empirical importance to the spectral shape of many GRBs, and the analysis performed was devised to be as thorough and objective as possible. We describe in detail our procedures and criteria for the analyses, and present the bulk results in the form of parameter distributions. This catalog should be considered an official product from the BATSE Science Team, and the data files containing the complete results are available from the High-Energy Astrophysics Science Archive Research Center (HEASARC)

  1. GBM: a gamma-ray burst monitor for GLAST

    NASA Astrophysics Data System (ADS)

    Lichti, Giselher G.; Briggs, Michael S.; Diehl, Roland; Fishman, Gerald J.; Kippen, Richard M.; Kouveliotou, Chryssa; Meegan, Charles A.; Paciesas, William S.; Preece, Robert S.; Schoenfelder, Volker; von Kienlin, Andreas

    2003-03-01

    One of the scientific objectives of the GLAST mission is the study of gamma-ray bursts (GRBs) which will be measured by the Large-Area Telescope, the main instrument of GLAST, in the energy range from ~20 MeV to ~300 GeV. In order to extend the energy measurement towards lower energies a secondary instrument, the GLAST Burst Monitor (GBM) will measure GRBs from ~10 keV to ~25 MeV and will thus allow the investigation of the relation between the keV and the MeV-GeV emission from GRBs. The GBM consists of 12 circular NaI crystal discs and 2 cylindrical BGO crystals. The NaI crystals are optimized for gamma radiation from ~10 keV to ~1 MeV and the BGO crystals from ~150 keV to ~25 MeV. The NaI crystals are oriented in such a way that the measured relative counting rates allow a rapid determination of the position of a gamma-ray burst within a wide FoV of ~8.6 sr. This position will be communicated within seconds to the LAT which may then be reoriented to observe the long-lasting high-energy gamma-ray emission from GRBs. This will allow the exploration of the unknown aspects of the high-energy burst emission and their connection with the well-known low-energy emission. Another important feature of the GBM is its high time resolution of ~10 microseconds for time-resolved gamma-ray spectroscopy.

  2. THE ENGINES BEHIND SUPERNOVAE AND GAMMA-RAY BURSTS

    SciTech Connect

    FRYER, CHRISTOPHER LEE

    2007-01-23

    The authors review the different engines behind supernova (SNe) and gamma-ray bursts (GRBs), focusing on those engines driving explosions in massive stars: core-collapse SNe and long-duration GRBs. Convection and rotation play important roles in the engines of both these explosions. They outline the basic physics and discuss the wide variety of ways scientists have proposed that this physics can affect the supernova explosion mechanism, concluding with a review of the current status in these fields.

  3. Ten Years of Gamma-Ray Bursts Observations with BATSE

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    The observed gamma-ray temporal, spectral, intensity and spatial distribution characteristics of GRBs from data obtained from BATSE/Compton Observatory, will be described. The talk will concentrate on recent studies of burst properties, correlations of GRB parameters and other statistical studies that have only recently come to light with the unprecedented sample of over 2700 GRBS. Recent studies of possible observational biases, un-triggered GRBs and threshold calculations for BATSE will also be described.

  4. High-energy emission from gamma-ray bursts

    SciTech Connect

    Nolan, P.L.; Share, G.H.; Matz, S.; Chupp, E.L.; Forrest, D.J.; Rieger, E.

    1984-05-26

    We discuss broad-band continuum spectroscopy of 17 gamma-ray bursts above 0.3 MeV. The spectra were fitted by 3 trial functions, none of which provided an adequate fit to all the spectra. Most were too hard for a thermal bremsstarhlung function. Harder functional forms, such as thermal synchrotron or power-law, provide better fits for most of the spectra. The strong emission observed above 1 MeV raises some interesting theoretical questions.

  5. Observations of short-duration gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Pozanenko, Alexei; Volnova, Alina; Tungalag, Namkhai; Elenin, Leonid; Molotov, Igor; Voropaev, Victor; Schmalz, Sergey

    2014-09-01

    Gamma-ray bursts (GRB) are the most powerful cosmological catastrophes in the Universe, with energy releases of 1048 - 1053 erg within a few tens of seconds. It is widely believed that progenitors of the short-duration class of GRB can be merging relativistic binary systems such as a neutron star (NS) and a black hole (BH) or NS-NS. We review the physics of GRBs, their phenomenological properties and observational evidence of GRBs, emphasizing optical observations of GRBs from Mongolia.

  6. Fast Fourier transformation results from gamma-ray burst profiles

    NASA Technical Reports Server (NTRS)

    Kouveliotou, Chryssa; Norris, Jay P.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Paciesas, W. S.

    1992-01-01

    Several gamma-ray bursts in the BATSE data have sufficiently long durations and complex temporal structures with pulses that appear to be spaced quasi-periodically. In order to test and quantify these periods we have applied fast Fourier transformations (FFT) to all these events. We have also performed cross spectral analyses of the FFT of the two extreme (high-low) energy bands in each case to determine the lead/lag of the pulses in different energies.

  7. Formation of cyclotron lines in gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Alexander, S. G.; Meszaros, P.

    1989-01-01

    A transmission model of gamma-ray burst sources is studied using the relativistic QED magnetic-resonant opacities including multiple photon scattering, incorporated into a discrete-ordinate radiative-transport scheme. The physics of the cyclotron line-producing region is discussed in general, and the expected line profiles, relative harmonic strengths, and polarizations are indicated under various conditions. The calculated spectra for these models show good agreement with the spectra reported from Ginga for GB 880205 and GB 870303.

  8. The width of gamma-ray burst spectra

    NASA Astrophysics Data System (ADS)

    Axelsson, Magnus; Borgonovo, Luis

    2015-03-01

    The emission processes active in the highly relativistic jets of gamma-ray bursts (GRBs) remain unknown. In this paper, we propose a new measure to describe spectra: the width of the EFE spectrum, a quantity dependent only on finding a good fit to the data. We apply this to the full sample of GRBs observed by Fermi/Gamma-ray Burst Monitor (GBM) and Compton Gamma-ray Observatory/Burst and Transient Source Experiment (BATSE). The results from the two instruments are fully consistent. We find that the median widths of spectra from long and short GRBs are significantly different (chance probability <10-6). The width does not correlate with either duration or hardness, and this is thus a new, independent distinction between the two classes. Comparing the measured spectra with widths of spectra from fundamental emission processes - synchrotron and blackbody radiation - the results indicate that a large fraction of GRB spectra are too narrow to be explained by synchrotron radiation from a distribution of electron energies: for example, 78 per cent of long GRBs and 85 per cent of short GRBs are incompatible with the minimum width of standard slow cooling synchrotron emission from a Maxwellian distribution of electrons, with fast cooling spectra predicting even wider spectra. Photospheric emission can explain the spectra if mechanisms are invoked to give a spectrum much broader than a blackbody.

  9. Gamma Ray Burst Optical Counterpart Search Experiment (GROCSE)

    SciTech Connect

    Park, H.S.; Ables, E.; Bionta, R.M.

    1995-10-27

    GROCSE (Gamma-Ray Optical Counterpart Search Experiments) is a system of automated telescopes that search for simultaneous optical activity associated with gamma ray bursts in response to real-time burst notifications provided by the BATSE/BACODINE network. The first generation system, GROCSE 1, is sensitive down to Mv {approximately} 8.5 and requires an average of 12 seconds to obtain the first images of the gamma ray burst error box defined by the BACODINE trigger. The collaboration is now constructing a second generation system which has a 4 second slewing time and can reach Mv {approximately} 14 with a 5 second exposure. GROCSE 2 consists of 4 cameras on a single mount. Each camera views the night sky through a commercial Canon lens (f/1.8, focal length 200 mm) and utilizes a 2K x 2K Loral CCD. Light weight and low noise custom readout electronics were designed and fabricated for these CCDs. The total field of view of the 4 cameras is 17.6 x 17.6 {degree}. GROCSE II will be operated by the end of 1995. In this paper, the authors present an overview of the GROCSE system and the results of measurements with a GROCSE 2 prototype unit.

  10. Improved Limits on Gamma-Ray Burst Repetition from BATSE

    NASA Technical Reports Server (NTRS)

    Tegmark, Max; Hartmann, Dieter H.; Briggs, Michael S.; Meegan, Charles A.; Hakkila, Jon

    1996-01-01

    We tighten previous upper limits on gamma-ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more than 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to burst nu times each, then all models with (nu - 1)f greater than or equal to 0.05 are ruled out at 99% confidence, as compared to the best previous 99% limit (nu - 1)f greater than or equal to 0.27. At 95% confidence, our new limit is (nu - 1)f greater than or equal to 0.02. Thus, even a cluster of six events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma-ray bursts and that any repeater model is severely constrained by the near-perfect isotropy of their angular dis- tribution.

  11. The Third BATSE Gamma-Ray Burst Catalog

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.; Pendleton, Geoffrey N.; Briggs, Michael S.; Kouveliotou, Chryssa; Koshut, Thomas M.; Lestrade, John Patrick; Paciesas, William S.; McCollough, Michael L.; Brainerd, Jerome J.; Horack, John M.; Hakkila, Jon; Henze, William; Preece, Robert D.; Mallozzi, Robert S.; Fishman, Gerald J.

    1996-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) has triggered on 1122 cosmic gamma-ray bursts between 1991 April 19 and 1994 September 19. These events constitute the Third BATSE (3B) burst catalog. This catalog includes the events previously reported in the 2B catalog, which covered the time interval 1991 April 19 to 1993 March 9. We present tables of the burst occurrence times, locations, peak fluxes, fluences, and durations. In general, results from previous BATSE catalogs are confirmed here with greater statistical significance. The angular distribution is consistent with isotropy. The mean galactic dipole and quadrupole moments are within 0.6 a and 0.3 a, respectively, of the values expected for isotropy. The intensity distribution is not consistent with a homogeneous distribution of burst sources, with V/V(sub max) = 0.33 +/- 0.01. The duration distribution (T(sub 90)) exhibits bimodality, with peaks at approx. 0.5 and approx. 30 s. There is no compelling evidence for burst repetition, but only weak limits can be placed on the repetition rate.

  12. Galactic dual population models of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Higdon, J. C.; Lingenfelter, R. E.

    1994-01-01

    We investigate in more detail the properties of two-population models for gamma-ray bursts in the galactic disk and halo. We calculate the gamma-ray burst statistical properties, mean value of (V/V(sub max)), mean value of cos Theta, and mean value of (sin(exp 2) b), as functions of the detection flux threshold for bursts coming from both Galactic disk and massive halo populations. We consider halo models inferred from the observational constraints on the large-scale Galactic structure and we compare the expected values of mean value of (V/V(sub max)), mean value of cos Theta, and mean value of (sin(exp 2) b), with those measured by Burst and Transient Source Experiment (BATSE) and other detectors. We find that the measured values are consistent with solely Galactic populations having a range of halo distributions, mixed with local disk distributions, which can account for as much as approximately 25% of the observed BATSE bursts. M31 does not contribute to these modeled bursts. We also demonstrate, contrary to recent arguments, that the size-frequency distributions of dual population models are quite consistent with the BATSE observations.

  13. High-energy spectral breaks in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Teegarden, Bonnard J.; Cline, Thomas L.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Paciesas, William S.; Pendleton, Geoffrey N.; Matteson, James L.; Band, David L.

    1992-01-01

    Model fits are presented for 18 gamma-ray burst spectra from 100 keV to 27 MeV made with the BATSE spectroscopy detectors on the Compton Gamma Ray Observatory. Most of the bursts are well fitted as power laws with spectral indices between -1.36 and -2.29; however, five bursts show definite departures from a simple power-law fit at high energies. Three of these bursts are well fitted with broken power-law spectra and break energies of from 400 to 690 keV, such as might arise from photon-photon interactions. If so, then the source compactness and hence distance will be sharply constrained. Two of the bursts have spectra with sharply confined slope changes and are well fitted with broken power-law spectra with break energies of 1.2 and 1.6 MeV at peak, such as might arise from photon-magnetic field interactions. If so, then these spectral breaks provide strong evidence for the existence of high magnetic fields in the burst emission region.

  14. Improved Limits on Gamma-Ray Burst Repetition from BATSE

    NASA Technical Reports Server (NTRS)

    Tegmark, Max; Hartmann, Dieter H.; Briggs, Michael S.; Hakkila, Jon; Meegan, Charles A.

    1996-01-01

    We tighten previous upper limits on gamma-ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more than 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to burst upsilon times each, then all models with (upsilon - 1)f greater than or equal to 0.05 are ruled out at 99% confidence, as compared to the best previous 99% limit (upsilon - 1)f greater than or equal to 0.27. At 95% confidence, our new limit is (upsilon - 1)f greater than or equal to 0.02. Thus, even a cluster of six events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma-ray bursts and that any repeater model is severely constrained by the near-perfect isotropy of their angular distribution.

  15. Energy Injections in Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Yu, Y. B.; Wu, X. F.; Huang, Y. F.; Xu, M.

    2016-06-01

    In this study, we will introduce some special events, such as GRBs 081029, 100814A and 111209A. Unexpected features, such as multiple X-ray flares and significant optical rebrightenings, are observed in their afterglow light curves, unveiling the late-time activities of the central engines. Here, we will summarize our previous numerical results of these three bursts by using the energy injection model. Especially, we will focus on GRB 100814A, with an early-time shallow decay phase and a late-time significant rebrightening in its optical afterglow light curve. To explain the complex multi-band afterglow emission of GRB 100814A, we invoke a magnetar with spin evolution as its central engine. We argue that the optical shallow decay phase and the X-ray plateau are due to energy injection from t he magnetar in its early spin-down stage, while the significant optical rebrightening observed at late time naturally comes from the spin-up process of the magnetar, which is caused by subsequent fall back accretion.

  16. Gamma ray bursts: Short vs. long

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Nava, L.; Ghisellini, G.

    2011-04-01

    Short and long GRBs are thought to be two distinct classes based on their different duration and spectrum. Through the spectral analysis of two similarly selected samples of BATSE short and long GRBs, we show that short GRBs are harder than long events, confirming what found from the comparison of their hardness ratio. However, this spectral diversity seems to be due to a harder low energy spectral component of short GRBs, rather than a (slightly higher) peak energy. Interestingly short GRBs have a spectrum which is similar to the spectrum of the emission of the first 1-2 s of long events. We find evidence that short GRBs are inconsistent with the Epeak-Eiso correlation defined by long bursts while they follow the same Epeak-Liso correlation of long GRBs. These results, coupled to the similar variability timescale of short events and the first seconds of long ones, suggest that a common (or similar) dissipation mechanism could operate in both classes. The difference in the duration would then be due mainly to the central engine lifetime.

  17. The SWIFT Gamma-Ray Burst X-Ray Telescope

    NASA Technical Reports Server (NTRS)

    Hill, J. E.; Burrows, D. N.; Nousek, J. A.; Wells, A.; Chincarini, G.; Abbey, A. F.; Angelini, L.; Beardmore, A.; Brauninger, H. W.; Chang, W.

    2006-01-01

    The Swift Gamma-Ray Burst Explorer is designed to make prompt multi-wavelength observations of Gamma-Ray Bursts and GRB afterglows. The X-ray Telescope enables Swift to determine GRB positions with a few arcseconds accuracy within 100 seconds of the burst onset. The XRT utilizes a mirror set built for JET-X and an XMM-Newton/ EPIC MOS CCD detector to provide a sensitive broad-band (0.2-10 keV) X-ray imager with an effective area of more than 120 sq cm at 1.5 keV, a field of view of 23.6 x 23.6 arcminutes, and an angular resolution of 18 arcseconds (HPD). The detection sensitivity is 2x10(exp 14) erg/sq cm/s in 10(exp 4) seconds. The instrument provides automated source detection and position reporting within 5 seconds of target acquisition. It can also measure the redshifts of GRBs with Iron line emission or other spectral features. The XRT operates in an auto-exposure mode, adjusting the CCD readout mode automatically to optimize the science return as the source intensity fades. The XRT measures spectra and lightcurves of the GRB afterglow beginning about a minute after the burst and follows each burst for days or weeks. We provide an overview of the X-ray Telescope scientific background from which the systems engineering requirements were derived, with specific emphasis on the design and qualification aspects from conception through to launch. We describe the impact on cleanliness and vacuum requirements for the instrument low energy response and to maintain the high sensitivity to the fading signal of the Gamma-ray Bursts.

  18. Temporal alternative classification of Gamma Ray Burst and spectral properties

    NASA Astrophysics Data System (ADS)

    Vasquez, N.; Bernal, S.

    2017-07-01

    After decades of the discovery of Gamma Ray Bursts (GRBs) there is not common consensus on their classification and progenitors. With no correlation with barionic matter their origin continues being a mystery. Using a large sample of the third Fermi burst catalog (2016) we will extract the emission time and canonical duration time to explore alternative classifications in the spectral properties and temporal estimator plane in the observer frame to extend the study in the burst frame. Among the 1405 bursts detected in the third catalog, 1175 are classified as long-soft bursts and 191 were simultaneously detected by Swift. Our analysis is centered only in the long-soft bursts detected by GBM Fermi detector in the energy range 50 - 300 keV. We aim to compare the results with a previous similar analysis done with Swift burst data, which suggest a bimodal distribution of long soft burst in the rest frame. This work will be done in three steps, first the analysis of burst simultaneously detected by both observatories. Second the analysis of the sample of long soft burst and then the selection of burst with redshift. We would like to explore the temporal distribution of two temporal estimators of GRBs, the canonical t90 and the emission time introduced by Mitrofanov (1997) in the observer frame and rest frame.

  19. Three precise gamma-ray burst source locations

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.

    1984-01-01

    The precise source regions of three moderately intense gamma ray bursts are derived. These events were observed with the first interplanetary burst sensor network. The optimum locations of the detectors, widely separated throughout the inner solar system, allowed for high accuracy, over-determined source fields of size 0.7 to 7.0 arc-min(2). All three locations are at fairly high galactic latitude in regions of low source confusion; none can be identified with a steady source object. Archived photographs were searched for optical transients that are able to be associated with these source fields; one such association was made.

  20. Recent DMSP satellite detections of gamma-ray bursts

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R. W.; Griffee, J. W.

    1998-05-16

    Gamma-ray burst detectors are aboard seven U.S. Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, two of which are currently in use. Their 800 km altitude orbits give a field of view to 117 degrees from the zenith. A great many bursts have been detected, usually in coincidence with detections by GRO or other satellites such as PVO or Ulysses. The directions of the sources can be determined with considerable accuracy from such correlated observations, even when neither GRO nor BeppoSAX is involved. Results obtained from the most recently launched satellites (DMSP 13 and DMSP 14) are given in this paper.

  1. Physics issues of gamma ray burst spectral evolution

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.

    1992-01-01

    It is suggested that the study of the rapid spectral evolution of gamma-ray bursts may provide information on the emission and particle energizing mechanisms independently of the ultimare astrophysical or energy source models. Correlation analysis of spectral hardness and other measurable quantities suggests that the luminosity is proportional to color temperature, especially during spike decay. The use of the peak power energy as a gauge of spectral hardness is proposed, and the notion of Type I and Type II burst spikes is introduced. If the temperature-luminosity correlations are confirmed, then an accelerating pair avalanche scenario may be worth pursuing.

  2. Gamma-Ray Bursts and Population III Stars

    NASA Astrophysics Data System (ADS)

    Toma, Kenji; Yoon, Sung-Chul; Bromm, Volker

    2016-12-01

    Gamma-ray bursts (GRBs) are ideal probes of the epoch of the first stars and galaxies. We review the recent theoretical understanding of the formation and evolution of the first (so-called Population III) stars, in light of their viability of providing GRB progenitors. We proceed to discuss possible unique observational signatures of such bursts, based on the current formation scenario of long GRBs. These include signatures related to the prompt emission mechanism, as well as to the afterglow radiation, where the surrounding intergalactic medium might imprint a telltale absorption spectrum. We emphasize important remaining uncertainties in our emerging theoretical framework.

  3. GRO: Black hole models for gamma ray bursts

    NASA Technical Reports Server (NTRS)

    Shaham, Jacob

    1993-01-01

    This grant deals with the production of gamma-ray bursts (GRB's) close to horizons of black holes (BH's), mainly via accretion of small chunks of matter onto extreme Kerr BH's. In the past year, we laid the ground work for actual calculations close to Kerr BH's. Because of technical reasons, actual work has only started very recently. Following the detailed list of research subprojects as per our original proposal, we have performed research in the following areas: spectrum calculation; burst dynamics; tidal capture and primordial cloud collapse; halo density profile; and capture of other objects.

  4. Features in the spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Stanek, Krzysztof Z.; Paczynski, Bohdan; Goodman, Jeremy

    1993-01-01

    Gravitational lensing of cosmological gamma-ray bursts by objects in the mass range about 10 exp 17 to 10 exp 20 g (femtolensing) may introduce complicated interference patterns that might be interpreted as absorption or emission lines in the bursts' spectra. This phenomenon, if detected, may be used as a unique probe of dark matter in the universe. The BATSE spectral data should allow one to detect such spectral features or to put significant upper limits on the cosmic density of a dark matter component that may be in the femtolensing range. Software to generate theoretical spectra has been developed, and it is accessible over the computer network with anonymous ftp.

  5. Hyperaccreting Black Hole as Gamma-Ray Burst Central Engine. I. Baryon Loading in Gamma-Ray Burst Jets

    NASA Astrophysics Data System (ADS)

    Lei, Wei-Hua; Zhang, Bing; Liang, En-Wei

    2013-03-01

    A hyperaccreting stellar-mass black hole has been long speculated as the best candidate for the central engine of gamma-ray bursts (GRBs). Recent rich observations of GRBs by space missions such as Swift and Fermi pose new constraints on GRB central engine models. In this paper, we study the baryon-loading processes of a GRB jet launched from a black hole central engine. We consider a relativistic jet powered by \

  6. High-Energy Spectral Signatures in Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Baring, Matthew D.

    1999-01-01

    One of the principal results obtained by the EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) was the detection of several gamma-ray bursts (GRBs) above 100 MeV. The broad-band spectra obtained for these bursts gave no indication of any high-energy spectral attenuation that might preclude detection of bursts by ground-based Cerenkov telescopes (ACTs), thus motivating several TeV observational programs. This paper explores the expectations for the spectral properties in the TeV and sub-TeV bands for bursts, in particular how attenuation of photons by pair creation internal to the source modifies the spectrum to produce distinctive spectral signatures. The energy of spectral breaks and the associated spectral indices provide valuable information that can constrain the bulk Lorentz factor of the GRB outflow at a given time. These characteristics define palpable observational goals for ACT programs, and strongly impact the observability of bursts in the TeV band.

  7. High-Energy Spectral Signatures in Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.

    2000-01-01

    One of the principal results obtained by the EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) was the detection of several gamma-ray bursts (GRBs) above 100 MeV. The broad-band spectra obtained for these bursts gave no indication of any high energy spectral attenuation that might preclude detection of bursts by ground-based Cerenkov telescopes (ACTs), thus motivating several TeV observational programs. This paper explores the expectations for the spectral properties in the TeV and sub-TeV bands for bursts, in particular how attenuation of photons by pair creation internal to the source modifies the spectrum to produce distinctive spectral signatures. The energy of spectral breaks and the associated spectral indices provide valuable information that can constrain the bulk Lorentz factor of the GRB outflow at a given time. These characteristics define palpable observational goals for ACT programs, and strongly impact the observability of bursts in the TeV band.

  8. Gamma-Ray Burst Host Galaxies Have "Normal" Luminosities.

    PubMed

    Schaefer

    2000-04-10

    The galactic environment of gamma-ray bursts can provide good evidence about the nature of the progenitor system, with two old arguments implying that the burst host galaxies are significantly subluminous. New data and new analysis have now reversed this picture: (1) Even though the first two known host galaxies are indeed greatly subluminous, the next eight hosts have absolute magnitudes typical for a population of field galaxies. A detailed analysis of the 16 known hosts (10 with redshifts) shows them to be consistent with a Schechter luminosity function with R*=-21.8+/-1.0, as expected for normal galaxies. (2) Bright bursts from the Interplanetary Network are typically 18 times brighter than the faint bursts with redshifts; however, the bright bursts do not have galaxies inside their error boxes to limits deeper than expected based on the luminosities for the two samples being identical. A new solution to this dilemma is that a broad burst luminosity function along with a burst number density varying as the star formation rate will require the average luminosity of the bright sample (>6x1058 photons s-1 or>1.7x1052 ergs s-1) to be much greater than the average luminosity of the faint sample ( approximately 1058 photons s-1 or approximately 3x1051 ergs s-1). This places the bright bursts at distances for which host galaxies with a normal luminosity will not violate the observed limits. In conclusion, all current evidence points to gamma-ray burst host galaxies being normal in luminosity.

  9. A Strange Supernova with a Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

    1998-10-01

    Important Observations with La Silla Telescopes Several articles appear today in the scientific journal Nature about the strange supernova SN 1998bw that exploded earlier this year in the spiral galaxy ESO184-G82 . These studies indicate that this event was linked to a Gamma-Ray Burst and may thus provide new insights into this elusive phenomenon. Important observations of SN 1998bw have been made with several astronomical telescopes at the ESO La Silla Observatory by some of the co-authors of the Nature articles [1]. The measurements at ESO will continue during the next years. The early observations On April 25, the BeppoSAX satellite detected a Gamma-Ray Burst from the direction of the constellation Telescopium, deep in the southern sky. Although there is now general consensus that they originate in very distant galaxies, the underlying physical causes of these events that release great amounts of energy within seconds are still puzzling astronomers. Immediately after reports about the April 25 Burst had been received, astronomers at La Silla took some images of the sky region where the gamma-rays were observed as a "Target of Opportunity" (ToO) programme. The aim was to check if the visual light of one of the objects in the field had perhaps brightened when compared to exposures made earlier. This would then provide a strong indication of the location of the Gamma-Ray Burst. The digital exposures were transferred to the Italian/Dutch group around BeppoSax that had requested these ToO observations. Astronomers of this group quickly noticed a new, comparatively bright star, right on the arm of a small spiral galaxy. This galaxy was first catalogued in the 1970's during the ESO/Uppsala Survey of the Southern Sky and received the designation ESO184-G82 . It is located at a distance of about 140 million light-years. SN 1998bw ESO PR Photo 39a/98 ESO PR Photo 39a/98 [Preview - JPEG: 800 x 963 pix - 592k] [High-Res - JPEG: 3000 x 3612 pix - 4.1Mb] ESO PR Photo 39b/98

  10. Short Hard Gamma-Ray Bursts and their Afterglows

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon; De Rújula, A.

    2009-03-01

    Long-duration gamma-ray bursts (GRBs) and X-ray flashes (XRFs) are produced by highly relativistic jets ejected in core-collapse supernova (SN) explosions. The origin of short hard gamma-ray bursts (SHBs) has not been established. They may be produced by highly relativistic jets ejected in various processes: mergers of compact stellar objects, large-mass accretion episodes onto compact stars in close binaries or onto intermediate-mass black holes in dense stellar regions, phase transition in compact stars. Natural environments of such events are the dense cores of globular clusters, super star clusters and young SN remnants. We have used the cannonball model of GRBs to analyze all Swift SHBs with a well-sampled X-ray afterglow. We show that their prompt gamma-ray emission can be explained by inverse Compton scattering (ICS) of the progenitor's glory light and their extended soft emission component by either ICS of high-density radiation or synchrotron radiation (SR) in the high-density medium within the star cluster. The mechanism generating their afterglow is SR outside the cluster. No associated SN could be detected in the low luminosity nearby GRBs 060614 and 060505. We interpret them as SHBs seen relatively far off-axis.

  11. Gamma Ray Bursts from a Quantum Critical Surface

    SciTech Connect

    Chapline, G; Santiago, D I

    2002-11-20

    The logical inconsistency of quantum mechanics and general relativity can be avoided if the relativity principle fails for length scales smaller than the quantum coherence length for the vacuum state. Ordinarily this corresponds to energies near the Planck energy, but recently it has been pointed out that near to the event horizon of a black hole the coherence length can be much larger and Planck scale physics can take over at macroscopic distances from the event horizon. This has dramatic consequences for the phenomenology of black holes. If we assume that at the Planck scale elementary particles interact via a universal 4-point interaction and baryon number conservation is violated, then the rest mass of a star hitting the event horizon of a large black hole would be rapidly converted into a burst of gamma rays followed by a pulse of hard X-rays whose duration is on the order of the light transit time across the black hole. Predictions for the gamma ray spectra are strikingly similar to those observed for cosmic gamma ray bursts.

  12. The first Fermi-LAT Gamma-Ray burst catalog

    DOE PAGES

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

    2013-10-23

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (gsim 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above ~20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi andmore » processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. Here, we summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.« less

  13. THE FIRST FERMI-LAT GAMMA-RAY BURST CATALOG

    SciTech Connect

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Bastieri, D.; Bechtol, K.; Bloom, E. D.; Bellazzini, R.; Bregeon, J.; Bhat, P. N.; Bissaldi, E.; Bonamente, E.; Bonnell, J.; Brandt, T. J.; Bouvier, A. E-mail: giacomov@slac.stanford.edu; and others

    2013-11-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (∼> 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above ∼20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  14. The First Fermi-LAT Gamma-Ray Burst Catalog

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Ajello, M.; Asano, K.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bhat, P. N.; Bissaldi, E.; Bloom, E. D.; Bonamente, E.; Bonnell, J.; Bouvier, A.; Brandt, T. J.; Bregeon, J.; Brigida, M.; Bruel, P.; Buehler, R.; Burgess, J. Michael; Buson, S.; Byrne, D.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Cecchi, C.; Charles, E.; Chaves, R. C. G.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Cutini, S.; D'Ammando, F.; de Angelis, A.; de Palma, F.; Dermer, C. D.; Desiante, R.; Digel, S. W.; Dingus, B. L.; Di Venere, L.; Drell, P. S.; Drlica-Wagner, A.; Dubois, R.; Favuzzi, C.; Ferrara, E. C.; Fitzpatrick, G.; Foley, S.; Franckowiak, A.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Glanzman, T.; Godfrey, G.; Goldstein, A.; Granot, J.; Grenier, I. A.; Grove, J. E.; Gruber, D.; Guiriec, S.; Hadasch, D.; Hanabata, Y.; Hayashida, M.; Horan, D.; Hou, X.; Hughes, R. E.; Inoue, Y.; Jackson, M. S.; Jogler, T.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Kataoka, J.; Kawano, T.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Larsson, S.; Latronico, L.; Lee, S.-H.; Longo, F.; Loparco, F.; Lovellette, M. N.; Lubrano, P.; Massaro, F.; Mayer, M.; Mazziotta, M. N.; McBreen, S.; McEnery, J. E.; McGlynn, S.; Michelson, P. F.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Murgia, S.; Nemmen, R.; Nuss, E.; Nymark, T.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orienti, M.; Orlando, E.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Pelassa, V.; Perkins, J. S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T. A.; Preece, R.; Racusin, J. L.; Rainò, S.; Rando, R.; Rau, A.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romoli, C.; Roth, M.; Ryde, F.; Saz Parkinson, P. M.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Sonbas, E.; Spandre, G.; Spinelli, P.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takeuchi, Y.; Tanaka, Y.; Thayer, J. G.; Thayer, J. B.; Thompson, D. J.; Tibaldo, L.; Tierney, D.; Tinivella, M.; Torres, D. F.; Tosti, G.; Troja, E.; Tronconi, V.; Usher, T. L.; Vandenbroucke, J.; van der Horst, A. J.; Vasileiou, V.; Vianello, G.; Vitale, V.; von Kienlin, A.; Winer, B. L.; Wood, K. S.; Wood, M.; Xiong, S.; Yang, Z.

    2013-11-01

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (gsim 20 MeV) γ-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above ~20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  15. Gamma-ray burst and spectroscopy instrumentation development at the Goddard Space Flight Center

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.

    1986-01-01

    This paper summarizes the activities that are specifically related to the development of instrumentation for gamma-ray astronomy. Three programs are described: (1) the Gamma-Ray Imaging Spectrometer (GRIS), a balloon-borne array of seven germanium detectors for high-resolution spectrographic studies of persistent gamma-ray sources; (2) the Transient Gamma-Ray Spectrometer (TGRS), a single radiatively-cooled germanium detector for the spectrographic study of gamma-ray bursts, and (3) the Rapidly Moving Telescope (RMT), a ground-based optical telescope for the detection and study of short-lived optical transients, particularly those that occur in coincidence with gamma-ray bursts.

  16. The AGILE Mission and Gamma-Ray Bursts

    SciTech Connect

    Longo, Francesco; Tavani, M.; Barbiellini, G.; Argan, A.; Basset, M.; Boffelli, F.; Bulgarelli, A.; Caraveo, P.; Cattaneo, P.; Chen, A.; Costa, E.; Del Monte, E.; Di Cocco, G.; Di Persio, G.; Donnarumma, I.; Feroci, M.; Fiorini, M.; Foggetta, L.; Froysland, T.; Frutti, M.

    2007-05-01

    The AGILE Mission will explore the gamma-ray Universe with a very innovative instrument combining for the first time a gamma-ray imager and a hard X-ray imager. AGILE will be operational at the beginning of 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources, Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV. The broadband detection of GRBs and the study of implications for particle acceleration and high energy emission are primary goals of the mission. AGILE can image GRBs with 2-3 arcminute error boxes in the hard X-ray range, and provide broadband photon-by photon detection in the 15-45 keV, 03-50 MeV, and 30 MeV-30 GeV energy ranges. Microsecond on-board photon tagging and a {approx} 100 microsecond gamma-ray detection deadtime will be crucial for fast GRB timing. On-board calculated GRB coordinates and energy fluxes will be quickly transmitted to the ground by an ORBCOMM transceiver. AGILE is now (January 2007) undergoing final satellite integration and testing. The PLS V launch is planned in spring 2007. AGILE is then foreseen to be fully operational during the summer of 2007.

  17. Cosmic Forensics Confirms Gamma-Ray Burst And Supernova Connection

    NASA Astrophysics Data System (ADS)

    2003-03-01

    Scientists announced today that they have used NASA's Chandra X-ray Observatory to confirm that a gamma-ray burst was connected to the death of a massive star. This result is an important step in understanding the origin of gamma-ray bursts, the most violent events in the present-day universe. "If a gamma-ray burst were a crime, then we now have strong circumstantial evidence that a supernova explosion was at the scene," said Nathaniel Butler of Massachusetts Institute of Technology in Cambridge, lead author of a paper presented today at the meeting of the High Energy Division of the American Astronomical Society. Chandra was able to obtain an unusually long observation (approximately 21 hours) of the afterglow of GRB 020813 (so named because the High-Energy Transient Explorer, HETE, discovered it on August 13, 2002.) A grating spectrometer aboard Chandra revealed an overabundance of elements characteristically dispersed in a supernova explosion. Narrow lines, or bumps, due to silicon and sulfur ions (atoms stripped of most of their electrons) were clearly identified in the X-ray spectrum of GRB 020813. "Our observation of GRB 020813 supports two of the most important features of the popular supra-nova model for gamma-ray bursts," said Butler. "An extremely massive star likely exploded less than two months prior to the gamma-ray burst, and the radiation from the gamma-ray burst was beamed into a narrow cone." An analysis of the data showed that the ions were moving away from the site of the gamma-ray burst at a tenth the speed of light, probably as part of a shell of matter ejected in the supernova explosion. The line features were observed to be sharply peaked, indicating that they were coming from a narrow region of the expanding shell. This implies that only a small fraction of the shell was illuminated by the gamma-ray burst, as would be expected if the burst was beamed into a narrow cone. The observed duration of the afterglow suggests a delay of about 60 days

  18. A complete sample of long bright Swift gamma ray bursts.

    PubMed

    Tagliaferri, Gianpiero; Salvaterra, Ruben; Campana, Sergio; Covino, Stefano; D'Avanzo, Paolo; Fugazza, Dino; Ghirlanda, Giancarlo; Ghisellini, Gabriele; Melandri, Andrea; Nava, Lara; Sbarufatti, Boris; Vergani, Susanna

    2013-06-13

    Complete samples are the basis of any population study. To this end, we selected a complete subsample of Swift long bright gamma ray bursts (GRBs). The sample, made up of 58 bursts, was selected by considering bursts with favourable observing conditions for ground-based follow-up observations and with the 15-150 keV 1 s peak flux above a flux threshold of 2.6 photons cm(-2) s(-1). This sample has a redshift completeness level higher than 90 per cent. Using this complete sample, we investigate the properties of long GRBs and their evolution with cosmic time, focusing in particular on the GRB luminosity function, the prompt emission spectral-energy correlations and the nature of dark bursts.

  19. Strategies for Studying the Sources of Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Norris, J. P.; Hurley, K. C.

    2003-01-01

    The study of gamma ray bursts (GRBs) has rapidly evolved in recent years with the discovery of their cosmological nature and with BATSE, BeppoSAX, HETE and the IPN enabling a wide variety of associated . afterglow measurements. Multiwavelength observations ranging through the radio, optical, soft and hard x-ray, and gamma-ray regimes have exploded the field of GRB interpretation. Also, the Amanda, Milagro and LIGO experiments can search for related neutrino, cosmic-ray photon, and gravitational radiation events, even with the delayed alerts, such as from the IPN. The infrared region, where the optical emissions from sources at the extreme distances may be shifted, will become important but is undersubscribed. The soon-to-be launched Swift mission will greatly broaden the GRB discipline, and a strategy for associated ground-based measurements is outlined. The need for the improved global distribution of all instruments, in particular, robotic infrared detectors, is cited.

  20. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Tueller, Jack

    2007-01-01

    There is a great synergy between the Swift and INTEGRAL missions. Swift provides wide-field hard x-ray monitoring and sensitive x-ray and UV/optical observations. INTEGRAL provides optical through gamma-ray coverage with emphasis on hard xray imaging and gamma-ray spectroscopy. For hard x-ray survey studies, the BAT and IBIS instruments are complementary with BAT covering the full sky every day and IBIS scanning the galactic plane. For GRBs, Swift follows up bursts detected by INTEGRAL. X-ray and optical observations give arcsecond positions and afterglow lightcurves. For IGR sources, X-ray observations identify counterparts. The joint BAT and IBIS survey data are giving the most complete picture of the hard x-ray sky ever obtained. This talk will review Swift capabilities and discuss joint observations that are taking place and planned

  1. Gamma-ray bursts at high and very high energies

    NASA Astrophysics Data System (ADS)

    Piron, Frédéric

    2016-06-01

    Gamma-Ray Bursts (GRBs) are extra-galactic and extremely energetic transient emissions of gamma rays, which are thought to be associated with the death of massive stars or the merger of compact objects in binary systems. Their huge luminosities involve the presence of a newborn stellar-mass black hole emitting a relativistic collimated outflow, which accelerates particles and produces non-thermal emissions from the radio domain to the highest energies. In this article, I review recent progresses in the understanding of GRB jet physics above 100 MeV, based on Fermi observations of bright GRBs. I discuss the physical implications of these observations and their impact on GRB modeling, and I present some prospects for GRB observation at very high energies in the near future. xml:lang="fr"

  2. Testing the Gamma-Ray Burst Energy Relationships

    NASA Technical Reports Server (NTRS)

    Band, David L.; Preece, Robert D.

    2005-01-01

    Building on Nakar & Piran's analysis of the Amati relation relating gamma-ray burst peak energies E(sub p) and isotropic energies E(sub iso ) we test the consistency of a large sample of BATSE bursts with the Amati and Ghirlanda (which relates peak energies and actual gamma-ray energies E(sub gamma)) relations. Each of these relations can be exp ressed as a ratio of the different energies that is a function of red shift (for both the Amati and Ghirlanda relations) and beaming fraction f(sub B) (for the Ghirlanda relation). The most rigorous test, whic h allows bursts to be at any redshift, corroborates Nakar & Piran's r esult - 88% of the BATSE bursts are inconsistent with the Amati relat ion - while only l.6% of the bursts are inconsistent with the Ghirlan da relation if f(sub B) = 1. Modelling the redshift distribution resu lts in an energy ratio distribution for the Amati relation that is sh ifted by an order of magnitude relative to the observed distributions; any sub-population satisfying the Amati relation can comprise at mos t approx. 18% of our burst sample. A similar analysis of the Ghirland a relation depends sensitively on the beaming fraction distribution f or small values of f(sub B); for reasonable estimates of this distrib ution about a third of the burst sample is inconsistent with the Ghir landa relation. Our results indicate that these relations are an artifact of the selection effects of the burst sample in which they were f ound; these selection effects may favor sub-populations for which the se relations are valid.

  3. Can we identify lensed gamma-ray bursts?

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Grossman, Scott A.

    1994-01-01

    A gravitationally lensed gamma-ray burst (GRB) would appear as multiple bursts with identical light curves, separated in time and differing only by the scaling of their amplitudes. In reality, the detected bursts will be noisy, and therefore they may be difficult to identify as lensed images. Furthermore, faint, intrinsically similar, yet distinct light curves may be falsely identified as lensing events. In this paper we develop two statistical tests to distinguish noisy burst light curves. We use Fourier analysis techniques to analyze the signals for both intrinsic variability and variability due to noise. We are able to determine the noise level, and we compare the bursts only at frequency channels that are signal dominated. Utilizing these methods, we are able to make quantitative statements about whether two bursts are distinct. We apply these statistics to scaled versions of two subbursts of GRB 910503 -- subbursts previously investigated by Wambsganss using a different statistical test. We find that our methods are able to distinguish these bursts at slightly smaller amplitudes than those at which Wambsganss's method succeeds. We then apply our techniques to 'candidate' lensing events taken from the Burst and Transient Source Experiment (BATSE) catalog, and we find that nearly all of them, except for the very shortest ones (durations approx. less than 3 sec), are distinguishable. We therefore expect that a majority of bursts will be distinguishable from one another.

  4. Can we identify lensed gamma-ray bursts?

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Grossman, Scott A.

    1994-01-01

    A gravitationally lensed gamma-ray burst (GRB) would appear as multiple bursts with identical light curves, separated in time and differing only by the scaling of their amplitudes. In reality, the detected bursts will be noisy, and therefore they may be difficult to identify as lensed images. Furthermore, faint, intrinsically similar, yet distinct light curves may be falsely identified as lensing events. In this paper we develop two statistical tests to distinguish noisy burst light curves. We use Fourier analysis techniques to analyze the signals for both intrinsic variability and variability due to noise. We are able to determine the noise level, and we compare the bursts only at frequency channels that are signal dominated. Utilizing these methods, we are able to make quantitative statements about whether two bursts are distinct. We apply these statistics to scaled versions of two subbursts of GRB 910503 -- subbursts previously investigated by Wambsganss using a different statistical test. We find that our methods are able to distinguish these bursts at slightly smaller amplitudes than those at which Wambsganss's method succeeds. We then apply our techniques to 'candidate' lensing events taken from the Burst and Transient Source Experiment (BATSE) catalog, and we find that nearly all of them, except for the very shortest ones (durations approx. less than 3 sec), are distinguishable. We therefore expect that a majority of bursts will be distinguishable from one another.

  5. Nucleosynthesis, neutrino bursts and gamma-rays from coalescing neutron stars

    NASA Technical Reports Server (NTRS)

    Eichler, David; Livio, Mario; Piran, Tsvi; Schramm, David N.

    1989-01-01

    It is pointed out here that neutron-star collisions should synthesize neutron-rich heavy elements, thought to be formed by rapid neutron capture (the r-process). Furthermore, these collisions should produce neutrino bursts and resultant bursts of gamma rays; the latter should comprise a subclass of observable gamma-ray bursts. It is argued that observed r-process abundances and gamma-ray burst rates predict rates for these collisions that are both significant and consistent with other estimates.

  6. Search for high energy gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Petkov, V. B.; Alekseenko, V. V.; Chernyaev, A. B.; Smirnov, D. V.; Karpov, S. N.; Khaerdinov, N. S.; Poddubny, V. Y.; Radchenkov, A. V.; Volchenko, V. I.; Yanin, A. F.; Zaichenko, A. N.

    2004-06-01

    The search for high energy gamma-ray bursts and high energy radiation (Eγ ≥ 10 GeV) in correlation with the gamma-ray bursts registered at low energies (BATSE Eγ = 30 - 500 keV) has been carried out at the "Andyrchy" array of the Baksan Neutrino Observatory, INR RAS. Using "Andyrchy" data collected during 1996 - 2001 years we have obtained a limit on the rate of gamma bursts with Δ t = (1 - 50) second duration and corresponding energy fluences W(Δ t) ≥ 5.6 × 10-3 × √{Δ t} erg/cm2 in the declination band 10° ≤ δ ≤ 70°: Ωlim = 2.0 × 10-8 sec-1 at 90% c.l. 147 events have come into the field of view of the "Andyrchy" array during the period of 1996 - 2000 years (θ ≤ 50°). Range of limits on the energy fluence carried away by high energy gammas in the bursts is Wmax = 6.5× 10-4 - 0.15 erg/cm2.

  7. Search of the energetic gamma-ray experiment telescope (EGRET) data for high-energy gamma-ray microsecond bursts

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Bertsch, D. L.; Dingus, B. L.; Esposito, J. A.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.

    1994-01-01

    Hawking (1974) and Page & Hawking (1976) investigated theoretically the possibility of detecting high-energy gamma rays produced by the quantum-mechanical decay of a small black hole created in the early universe. They concluded that, at the very end of the life of the small black hole, it would radiate a burst of gamma rays peaked near 250 MeV with a total energy of about 10(exp 34) ergs in the order of a microsecond or less. The characteristics of a black hole are determined by laws of physics beyond the range of current particle accelerators; hence, the search for these short bursts of high-energy gamma rays provides at least the possibility of being the first test of this region of physics. The Compton Observatory Energetic Gamma-Ray Experiment Telescope (EGRET) has the capability of detecting directly the gamma rays from such bursts at a much fainter level than SAS 2, and a search of the EGRET data has led to an upper limit of 5 x 10(exp -2) black hole decays per cu pc per yr, placing constraints on this and other theories predicting microsecond high-energy gamma-ray bursts.

  8. Search of the energetic gamma-ray experiment telescope (EGRET) data for high-energy gamma-ray microsecond bursts

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Bertsch, D. L.; Dingus, B. L.; Esposito, J. A.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.

    1994-01-01

    Hawking (1974) and Page & Hawking (1976) investigated theoretically the possibility of detecting high-energy gamma rays produced by the quantum-mechanical decay of a small black hole created in the early universe. They concluded that, at the very end of the life of the small black hole, it would radiate a burst of gamma rays peaked near 250 MeV with a total energy of about 10(exp 34) ergs in the order of a microsecond or less. The characteristics of a black hole are determined by laws of physics beyond the range of current particle accelerators; hence, the search for these short bursts of high-energy gamma rays provides at least the possibility of being the first test of this region of physics. The Compton Observatory Energetic Gamma-Ray Experiment Telescope (EGRET) has the capability of detecting directly the gamma rays from such bursts at a much fainter level than SAS 2, and a search of the EGRET data has led to an upper limit of 5 x 10(exp -2) black hole decays per cu pc per yr, placing constraints on this and other theories predicting microsecond high-energy gamma-ray bursts.

  9. The First Fermi Gamma-ray Burst Monitor (GBM) Terrestrial Gamma-ray Flash (TGF) Catalog

    NASA Astrophysics Data System (ADS)

    Briggs, M. S.; Connaughton, V.; Stanbro, M.; Zhang, B.; Bhat, N.; Fishman, G. J.; Roberts, O.; Fitzpatrick, G.; McBreen, S.; Grove, J. E.; Chekhtman, A.

    2014-12-01

    We present summary results from the first catalog of Terrestrial Gamma-ray Flashes (TGFs) detected with the Gamma-ray Burst Monitor (GBM) on the Fermi Space Telescope. The catalog is expected to contain about 2600 TGFs and will be released both online, to conveniently provide the community with TGF parameters, and as a publication. Since the launch of Fermi in 2008 the TGF detection sensitivity of GBM has been improved several times, both in the flight software and in ground analysis. Starting in 2010 July individual photons were downloaded for portions of the orbits, enabling an off-line search that found weaker and shorter TGFs. Since 2012 November 26 this telemetry mode has been extended to continuous coverage -- in the first year of this data mode 841 TGFs were detected. The TGF sample is reliable, with cosmic rays rejected using data both from Fermi GBM and from the Large Area Telescope on Fermi. The online catalog will include times (UTC and solar), spacecraft geographic positions, durations, count intensities and other parameters (e.g., see the Bayesian Block analysis by O. Roberts). There will be separate tables for bright TGFs detected by the flight software and Terrestrial Electron Beams (TEBs).

  10. How Sample Completeness Affects Gamma-Ray Burst Classification

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Giblin, Timothy W.; Roiger, Richard J.; Haglin, David J.; Paciesas, William S.; Meegan, Charles A.; Six, N. Frank (Technical Monitor)

    2002-01-01

    Unsupervised pattern recognition algorithms support the existence of three gamma-ray burst classes; class I (long, large fluence bursts of intermediate spectral hardness), Class II (short, small fluence, hard bursts), and class III (soft bursts of intermediate durations and fluences). The algorithms surprisingly assign larger membership to class III than to either of the other two classes. A known systematic bias has been previously used to explain the existence of class III in terms of class I; this bias allows the fluences and durations of some bursts to be underestimated. We show that this bias primarily affects only the longest bursts and cannot explain the bulk of the class III properties. We resolve the question of class III existence by demonstrating how samples obtained using standard trigger mechanisms fail to preserve the duration characteristics of small peak flux bursts: (Sample incompleteness is thus primarily responsible for the existence of class III.) In order to avoid this incompleteness, we show how a new dual timescale peak flux can be defined in terms of peak flux and fluence. The dual timescale peak flux reserves the duration distribution of faint bursts and correlates either with spectral hardness (and presumably redshift) than either peak flux or fluence. The techniques presented here are generic and have applicability to the studies of other transient events. The results also indicate that pattern recognition algorithms are sensitive to sample completeness; this can influence the study of large astronomical databases such as those found in a Virtual Observatory.

  11. Bayesian Block Analysis of Terrestrial Gamma-ray Flashes Detected by the Gamma-ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Roberts, O.; Fitzpatrick, G.; McBreen, S.; Briggs, M. S.

    2014-12-01

    The Gamma-ray Burst Monitor (GBM) is one of two instruments aboard the Fermi Gamma-ray Space Telescope. Since the launch of the spacecraft in 2008, a sequence of flight software enhancements and new observing modes have resulted in the detection of over 2500 Terrestrial Gamma-ray Flashes (TGFs) by GBM. As a result, a catalogue of TGFs will be published and released online to provide the community with information on the most important characteristics of these TGFs. We will present a Bayesian Block analysis of the TGFs of this catalogue, obtaining for this large sample size the durations, peak times, hardness ratios, and delays between soft and hard counts.

  12. Two populations and models of gamma ray bursts

    NASA Technical Reports Server (NTRS)

    Katz, J. I.

    1993-01-01

    Gamma-ray burst statistics are best explained by a source population at cosmological distances, while spectroscopy and intensity histories of some individual bursts imply an origin on Galactic neutron stars. To resolve this inconsistency I suggest the presence of two populations, one at cosmological distances and the other Galactic. I build on ideas of Shemi and Piran (1990) and of Rees and Mesozaros (1992) involving the interaction of fireball debris with surrounding clouds to explain the observed intensity histories in bursts at cosmological distances. The distances to the Galactic population are undetermined because they are too few to affect the statistics of intensity and direction; I explain them as resulting from magnetic reconnection in neutron star magnetospheres. An appendix describes the late evolution of the debris as a relativistic blast wave.

  13. Climatic and biogeochemical effects of a galactic gamma ray burst

    NASA Astrophysics Data System (ADS)

    Melott, Adrian L.; Thomas, Brian C.; Hogan, Daniel P.; Ejzak, Larissa M.; Jackman, Charles H.

    2005-07-01

    It is likely that one or more gamma ray bursts within our galaxy have strongly irradiated the Earth in the last Gy. This produces significant atmospheric ionization and dissociation, resulting in ozone depletion and DNA-damaging ultraviolet solar flux reaching the surface for up to a decade. Here we show the first detailed computation of two other significant effects. Visible opacity of NO2 is sufficient to reduce solar energy at the surface up to a few percent, with the greatest effect at the poles, which may be sufficient to initiate glaciation. Rainout of dilute nitric acid could have been important for a burst nearer than our conservative ``nearest burst''. These results support the hypothesis that the characteristics of the Late Ordovician mass extinction are consistent with GRB initiation.

  14. Search for associations of radio pulses and gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Inzani, P.; Sironi, G.; Mandolesi, N.; Morigi, G.

    Continuous radio records obtained between July 1976 and May 1979 by automatic radiometers operating at 151 and 408 MHz from Medicina (Italy) are scanned for radio pulses associated with gamma ray bursts. In all, 65 gamma events are examined. For none of them is a definite association possible with a particular radio pulse detected within plus or minus 10 min from the burst onset. A statistical analysis of the delays between each gamma event and the nearest radio pulse, however, suggests to an 89 percent confidence level that approximately 20 percent of the bursts are associated with a weak radio precursor with a flux density greater than or equal to 10 to the -13th erg/sec sq cm MHz.

  15. BATSE spectroscopy catalog of bright gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Teegarden, Bonnard J.; Fantasia, Stephan F.; Palmer, David; Cline, Thomas L.; Matteson, James L.; Band, David L.; Ford, Lyle A.; Fishman, Gerald J.; Meegar, Charles A.

    1994-01-01

    This paper presents comprehensive results on the spectra of 30 bright gamma ray bursts (GRBs) as observed by the Spectroscopy Detectors (SDs) of the Burst And Transient Source Experiment (BATSE). The data selection was strict in including only spectra that are of high reliability for continuum shape studies. This BATSE Spectroscopy Catalog presents fluences, model fits (for five spectral models for three energy ranges), and photon spectra in a standard manner for each burst. Complete information is provided to describe the data selection and analysis procedures. The catalog results are also presented in electronic format (from the Compton Observatory Science Support Center) and CD-ROM format (AAS CD-ROM series, Vol. 2). These electronic formats also present the count spectra and detector response matrices so as to allow for independent study and fitting by researchers outside the BATSE Team. This BATSE Spectroscopy Catalog complements the catalog from BATSE Large Area Detector (LAD) data by Fishman et al. (1994).

  16. Gamma-ray bursts and terrestrial planetary atmospheres

    NASA Astrophysics Data System (ADS)

    Thomas, B. C.; Melott, A. L.

    2006-07-01

    We describe results of modelling the effects on Earth-like planets of long-duration gamma-ray bursts (GRBs) within a few kiloparsecs. A primary effect is generation of nitrogen oxide compounds which deplete ozone. Ozone depletion leads to an increase in solar UVB radiation at the surface, enhancing DNA damage, particularly in marine microorganisms such as phytoplankton. In addition, we expect increased atmospheric opacity due to build-up of nitrogen dioxide produced by the burst and enhanced precipitation of nitric acid. We review here previous work on this subject and discuss recent developments, including further discussion of our estimates of the rates of impacting GRBs and the possible role of short-duration bursts.

  17. Properties of gamma-ray burst progenitor stars.

    PubMed

    Kumar, Pawan; Narayan, Ramesh; Johnson, Jarrett L

    2008-07-18

    We determined some basic properties of stars that produce spectacular gamma-ray bursts at the end of their lives. We assumed that accretion of the outer portion of the stellar core by a central black hole fuels the prompt emission and that fall-back and accretion of the stellar envelope later produce the plateau in the x-ray light curve seen in some bursts. Using x-ray data for three bursts, we estimated the radius of the stellar core to be approximately (1 - 3) x 10(10) cm and that of the stellar envelope to be approximately (1 - 2) x 10(11) cm. The density profile in the envelope is fairly shallow, with rho approximately r(-2) (where rho is density and r is distance from the center of the explosion). The rotation speeds of the core and envelope are approximately 0.05 and approximately 0.2 of the local Keplerian speed, respectively.

  18. Observations of optical counterparts of Gamma-Ray bursts

    NASA Technical Reports Server (NTRS)

    Knight, Frederick K.

    1992-01-01

    This is a final report for a contract begun in Dec. 1987 and ended in Mar. 1989 to use the existing Lincoln Laboratory Experimental Test Site in Socorro, NM to search for optical counterparts to gamma-ray bursts. The objective was to develop an autonomous staring system to search for stationary, transient optical flashes. The search was to use an existing 31-inch telescope equipped with a sensitive video detector. The approach for the search was to develop real-time processing software to monitor the video signal from the detector and to record any transient, point-like flashes that occurred in the field of view. The system would have been able to detect fainter flashes (B is approximately 15(sup m) in 1/30 s, delta(m(sub v)) = 0.25(sup m)) than other systems but lacked a large field of view (only 1.2 deg diameter) necessary to give a high probability of detecting a random flash on the sky. As such, the plan was to monitor known gamma-ray burst error boxes and wait for a repetition of an earlier event. The high payoff of good sensitivity with high angular resolution (1 pixel = 10sec) and good time resolution (30 s) to allow post-burst searches warranted funding if the cost was not prohibitive. The contract began in the middle of the three-year cycle for High Energy Astrophysics Gamma-Ray Astronomy Research and Analysis Program. This final report briefly describes the portion of the plan completed under the original contract.

  19. 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.

  20. Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2004-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space- based observatories drive the end-to-end data analysis and distribution requirements. The Swift mission is managed by the GSFC, and includes an international team of contributors that each bring their unique perspective that have proven invaluable to the mission. The spacecraft bus, provided by Spectrum Astro, Inc. was procured through a Rapid Spacecraft Development Office (RSDO) contract by the GSFC. There are three instruments: the Burst Alert Telescope (BAT) provided by the GSFC; the X-Ray Telescope (XRT) provided by a team led by the Pennsylvania State University (PSU); and the Ultra-Violet Optical Telescope (UVOT), again managed by PSU. The Mission Operations Center (MOC) was developed by and is located at PSU. Science archiving and data analysis centers are located at the GSFC, in the UK and in Italy.

  1. GAMMA-RAY BURSTS ARE OBSERVED OFF-AXIS

    SciTech Connect

    Ryan, Geoffrey; Van Eerten, Hendrik; MacFadyen, Andrew; Zhang, Bin-Bin

    2015-01-20

    We constrain the jet opening angle and, for the first time, the off-axis observer angle for gamma-ray bursts in the Swift-XRT catalog by using the ScaleFit package to fit afterglow light curves directly to hydrodynamic simulations. The ScaleFit model uses scaling relations in the hydrodynamic and radiation equations to compute synthetic light curves directly from a set of high-resolution two-dimensional relativistic blast wave simulations. The data sample consists of all Swift-XRT afterglows from 2005 to 2012 with sufficient coverage and a known redshift, 226 bursts in total. We find that the jet half-opening angle varies widely but is commonly less than 0.1 rad. The distribution of the electron spectral index is also broad, with a median at 2.30. We find the observer angle to have a median value of 0.57 of the jet opening angle over our sample, which has profound consequences for the predicted rate of observed jet breaks and affects the beaming-corrected total energies of gamma-ray bursts.

  2. A MAD Model for Gamma-Ray Burst Variability

    DOE PAGES

    Lloyd-Ronning, Nicole Marie; Dolence, Joshua C.; Fryer, Christopher Lee

    2016-06-09

    Here we present a model for the temporal variability of long gamma-ray bursts during the prompt phase (the highly variable first 100 seconds or so), in the context of a magnet- ically arrested disk (MAD) around a black hole. In this state, sufficient magnetic flux is held on to the black hole such that it stalls the accretion near the inner region of the disk. The system transitions in and out of the MAD state, which we relate to the vari- able luminosity of the GRB during the prompt phase, with a characteristic timescale defined by the free fall timemore » in the region over which the accretion is arrested. We present simple analytic estimates of the relevant energetics and timescales, and com- pare them to gamma-ray burst observations. In particular, we show how this model can reproduce the characteristic one second time scale that emerges from various analyses of the prompt emission light curve. Finally, we also discuss how our model can accommodate the potentially physically important correlation between a burst quiescent time and the duration of its subsequent pulse (Ramirez-Ruiz & Merloni 2001).« less

  3. A MAD Model for Gamma-Ray Burst Variability

    SciTech Connect

    Lloyd-Ronning, Nicole Marie; Dolence, Joshua C.; Fryer, Christopher Lee

    2016-06-09

    Here we present a model for the temporal variability of long gamma-ray bursts during the prompt phase (the highly variable first 100 seconds or so), in the context of a magnet- ically arrested disk (MAD) around a black hole. In this state, sufficient magnetic flux is held on to the black hole such that it stalls the accretion near the inner region of the disk. The system transitions in and out of the MAD state, which we relate to the vari- able luminosity of the GRB during the prompt phase, with a characteristic timescale defined by the free fall time in the region over which the accretion is arrested. We present simple analytic estimates of the relevant energetics and timescales, and com- pare them to gamma-ray burst observations. In particular, we show how this model can reproduce the characteristic one second time scale that emerges from various analyses of the prompt emission light curve. Finally, we also discuss how our model can accommodate the potentially physically important correlation between a burst quiescent time and the duration of its subsequent pulse (Ramirez-Ruiz & Merloni 2001).

  4. A MAD Model for Gamma-Ray Burst Variability

    SciTech Connect

    Lloyd-Ronning, Nicole Marie; Dolence, Joshua C.; Fryer, Christopher Lee

    2016-06-09

    Here we present a model for the temporal variability of long gamma-ray bursts during the prompt phase (the highly variable first 100 seconds or so), in the context of a magnet- ically arrested disk (MAD) around a black hole. In this state, sufficient magnetic flux is held on to the black hole such that it stalls the accretion near the inner region of the disk. The system transitions in and out of the MAD state, which we relate to the vari- able luminosity of the GRB during the prompt phase, with a characteristic timescale defined by the free fall time in the region over which the accretion is arrested. We present simple analytic estimates of the relevant energetics and timescales, and com- pare them to gamma-ray burst observations. In particular, we show how this model can reproduce the characteristic one second time scale that emerges from various analyses of the prompt emission light curve. Finally, we also discuss how our model can accommodate the potentially physically important correlation between a burst quiescent time and the duration of its subsequent pulse (Ramirez-Ruiz & Merloni 2001).

  5. Delayed hard photons from gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Katz, J. I.

    1994-01-01

    The delayed hard (up to 25 GeV) photons observed more than an hour following a gamma-ray burst on 1994 February 17 may result from the collisions of relativistic nucleons with a dense cloud, producing pi(0). The required cloud density is approx. 2 x 10(exp 11)/cu cm. This cloud may be the remains of the disrupted envelope of a neutron star, and may survive as an excretion disk of approx. 10(exp 14) - 10 (exp 15) cm radius around the coalescing binary.

  6. Search for neutrinos from gamma-ray bursts with ANTARES

    SciTech Connect

    Schmid, Julia; Collaboration: ANTARES Collaboration

    2014-11-18

    ANTARES is the largest high-energy neutrino telescope in the Northern Hemisphere. A search for neutrinos in coincidence with gamma-ray bursts using ANTARES data from late 2007 to 2011 is presented here. An extended maximum likelihood ratio search was employed to optimise the discovery potential for a neutrino signal as predicted by a second-generation numerical model. No significant excess was found, so 90% confidence upper limits on the fluences as expected from analytically approximated neutrino-emission models as well as on up-to-date numerical predictions were placed.

  7. Gamma Ray Bursts in the Swift-Fermi Era

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Razzaque, Soebur

    2013-01-01

    Gamma-ray bursts (GRBs) are among the most violent occurrences in the universe. They are powerful explosions, visible to high redshift, and thought to be the signature of black hole birth. They are highly luminous events and provide excellent probes of the distant universe. GRB research has greatly advanced over the past 10 years with the results from Swift, Fermi and an active follow-up community. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  8. Effects of Galactic Gamma Ray Bursts on Planetary Biospheres

    NASA Astrophysics Data System (ADS)

    Cárdenas, Rolando; Martín, Osmel; Peñate, Liuba; Horvath, Jorge

    We examine the short-term effects that a galactic Gamma Ray Burst would cause on a planetary biosphere. The immediate environmental perturbation would arise due to the emission of an aurora like spectrum in the middle and low atmosphere, delivering at planet's surface a brief but intense ultraviolet flash. We calculated potential damages to both the photosynthetic and DNA apparatuses of unicellular organisms. We conclude that if the progenitor is 1-2 kiloparsec distant in the Milky Way, its main short-term bio-effect will be radiation damage in the photosynthetic machinery rather than in the genome.

  9. Gravitational waves and neutrinos from gamma-ray bursts

    SciTech Connect

    Fryer, Christopher Lee

    2010-01-01

    Gamma-Ray Bursts (GRBs) are not only strong sources of gammaray emission, but also of neutrinos and gravitational waves (GWs). Observat.ions of these particles can provide a good deal of insight into the progenitor and engine behind these outbursts. But to do so, these particles must be detected . Here we review the different phases of GW and neutrino emission from a range of GRB progenitors, outlining the features and detectability of these phases. Unfortunately, except for a few cases, the detection of non-photon emission is very difficult. But the potential gain from any detection make understanding these sources critically important.

  10. Analysis of gamma-ray burst spectra with cyclotron lines

    NASA Technical Reports Server (NTRS)

    Kargatis, Vincent; Liang, Edison P.

    1992-01-01

    Motivated by the recent developments in the cyclotron resonance upscattering of soft photons or CUSP model of Gamma Ray Burst (GBR) continuum spectra, we revisit a select database of GRBs with credible cyclotron absorption features. We measure the break energy of the continuum, the slope below the break and deduce the soft photon energy or the electron beam Lorentz factor cutoff. We study the correlation (or lack of) between various parameters in the context of the CUSP model. One surprise result is that there appears to be marginal correlation between the break energy and the spectral index below the break.

  11. Long Gamma-Ray Bursts Trace the Star Formation History

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon

    2014-04-01

    We show that if the broad-line supernova explosions of Type Ic (SNeIc) produce the bulk of the observed long duration gamma-ray bursts (LGRBs), including high- and low-luminosity LGRBs and X-ray flashes, and if the LGRBs have the geometry assumed in the cannonball model of LGRBs, then their rate, measured by Swift, and their redshift distribution are consistent with the star formation rate (SFR) over the entire range of redshifts where the SFR has been measured with sufficient accuracy.

  12. Long gamma-ray bursts trace the star formation history

    SciTech Connect

    Dado, Shlomo; Dar, Arnon

    2014-04-10

    We show that if the broad-line supernova explosions of Type Ic (SNeIc) produce the bulk of the observed long duration gamma-ray bursts (LGRBs), including high- and low-luminosity LGRBs and X-ray flashes, and if the LGRBs have the geometry assumed in the cannonball model of LGRBs, then their rate, measured by Swift, and their redshift distribution are consistent with the star formation rate (SFR) over the entire range of redshifts where the SFR has been measured with sufficient accuracy.

  13. Kinematic Origin of Correlations between Gamma-Ray Burst Observables

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon

    2012-04-01

    Recently, several new correlations between gamma-ray burst (GRB) observables have been discovered. Like previously well-established correlations, they challenge GRB models. Here, we show that in the cannonball (CB) model of GRBs, the newly discovered correlations have the same simple kinematic origin as those discovered earlier. They all result from the strong dependence of the observed radiations on the Lorentz and Doppler factors of the jet of highly relativistic plasmoids (CBs) that produces the observed radiations by interaction with the medium through which it propagates.

  14. KINEMATIC ORIGIN OF CORRELATIONS BETWEEN GAMMA-RAY BURST OBSERVABLES

    SciTech Connect

    Dado, Shlomo; Dar, Arnon E-mail: arnon@physics.technion.ac.il

    2012-04-20

    Recently, several new correlations between gamma-ray burst (GRB) observables have been discovered. Like previously well-established correlations, they challenge GRB models. Here, we show that in the cannonball (CB) model of GRBs, the newly discovered correlations have the same simple kinematic origin as those discovered earlier. They all result from the strong dependence of the observed radiations on the Lorentz and Doppler factors of the jet of highly relativistic plasmoids (CBs) that produces the observed radiations by interaction with the medium through which it propagates.

  15. Critical test of gamma-ray burst theories

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon

    2016-09-01

    Very long and precise follow-up measurements of the x-ray afterglow of very intense gamma-ray bursts (GRBs) allow a critical test of GRB theories. Here we show that the single power-law decay with time of the x-ray afterglow of GRB 130427A, the record-long and most accurately measured x-ray afterglow of an intense GRB by the Swift, Chandra, and XMM-Newton space observatories, and of all other known intense GRBs, is that predicted by the cannonball model of GRBs from their measured spectral index, while it disagrees with that predicted by the widely accepted fireball models of GRBs.

  16. Establishing the existence of lines in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Loredo, T. J.; Lamb, D. Q.

    1992-01-01

    A rigorous method for establishing the existence of lines in gamma-ray bursts is described which is based on Bayesian inference. In particular, it is shown how the problem of line detection can be reduced to that of comparing two models, a model consisting only of a continuum spectrum and a model with an additional feature in it. The simple case of a Gaussian line is considered, and it is noted that the results can be readily extended to the case of time-dependent lines.

  17. CATSAT: A small satellite for studying gamma-ray bursts

    SciTech Connect

    Vestrand, W. T.; Forrest, D. J.; Levenson, K. A.; Whitford, C.; Fletcher-Holmes, D.; Wells, A.; Owens, A.

    1999-12-15

    The Cooperative Astrophysics and Technology Satellite (CATSAT) is a University Explorer (UNEX) Class Mission that is being constructed by the University of New Hampshire and the University of Leicester. The primary scientific goal of the mission is to study the spectral properties of gamma-ray bursts in the energy range range from 500 eV to 5 MeV with particular emphasis on the 500 eV to 10 keV energy band. The satellite will be zenith pointed and flown in a 590 km sun-synchronous terminator orbit. Here we briefly discuss the mission and the expected scientific results.

  18. Identification of two classes of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Kouveliotou, Chryssa; Meegan, Charles A.; Fishman, Gerald J.; Bhat, Narayana P.; Briggs, Michael S.; Koshut, Thomas M.; Paciesas, William S.; Pendleton, Geoffrey N.

    1993-01-01

    We have studied the duration distribution of the gamma-ray bursts of the first BATSE catalog. We find a bimodality in the distribution, which separates GRBs into two classes: short events (less than 2 s) and longer ones (more than 2 s). Both sets are distributed isotropically and inhomogeneously in the sky. We find that their durations are anticorrelated with their spectral hardness ratios: short GRBs are predominantly harder, and longer ones tend to be softer. Our results provide a first GRB classification scheme based on a combination of the GRB temporal and spectral properties.

  19. Delayed hard photons from gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Katz, J. I.

    1994-01-01

    The delayed hard (up to 25 GeV) photons observed more than an hour following a gamma-ray burst on 1994 February 17 may result from the collisions of relativistic nucleons with a dense cloud, producing pi(0). The required cloud density is approx. 2 x 10(exp 11)/cu cm. This cloud may be the remains of the disrupted envelope of a neutron star, and may survive as an excretion disk of approx. 10(exp 14) - 10 (exp 15) cm radius around the coalescing binary.

  20. Spectral-luminosity relation within individual Fermi gamma rays bursts

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Nava, L.; Ghisellini, G.

    2010-02-01

    We study the spectra of all long gamma ray bursts (GRBs) of known redshift detected by the Fermi satellite untill the end of July 2009. Their fluxes and fluences are large enough to allow a time dependent study of their spectral characteristics in the 8 keV-1 MeV energy range. We find that the peak energy Epeak of their EL(E) spectrum correlates with the luminosity in a remarkably tight way within individual bursts. This time-resolved Epeak - Liso correlation is very similar for all the considered bursts and has a slope and normalisation similar to the analogous Epeak - Liso correlation defined by the time-integrated spectra of different bursts detected by several different satellites. For a few of the considered GRBs, we could also study the behaviour of the Epeak - Liso correlation during the rising and decaying phases of individual pulses within each burst, finding no differences. Our results indicate the presence of a similar physical mechanism, operating for the duration of different GRBs, tightly linking the burst luminosity with the peak energy of the spectrum emitted at different times. Such a physical mechanism is the same during the rise and decay phase of individual pulses composing a GRB. While calling for a robust physical interpretation, these results strongly indicate that the Epeak - Liso spectral energy correlation found considering the time-integrated spectra of different bursts is real and not the result of instrumental selection effects.

  1. Relationships between log N-log S and celestial distribution of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Nishimura, J.; Yamagami, T.

    1985-01-01

    The apparent conflict between log N-log S curve and isotropic celestial distribution of the gamma ray bursts is discussed. A possible selection effect due to the time profile of each burst is examined. It is shown that the contradiction is due to this selection effect of the gamma ray bursts.

  2. Short Gamma-Ray Bursts with Extended Emission

    NASA Technical Reports Server (NTRS)

    Norris, J. P.; Bonnell, J. T.

    2005-01-01

    The recent association of several short gamma-ray bursts (GRBs) with early type galaxies with low star formation rate demonstrates that short bursts arise from a different progenitor mechanism than long bursts. However, since the duration distributions of the two classes overlap, membership is not always easily established. The picture is complicated by the occasional presence of softer, extended emission lasting tens of seconds after the initial spike- like emission comprising an otherwise short burst. Using the large BATSE sample with time-tagged event (TTE) data, we show that the fundamental defining characteristic of the short burst class is that the initial spike exhibits negligible spectral evolution at energies above approx. 25 keV. This is behavior is nearly ubiquitous for the 260 bursts with T(sub 90) less than 2s where the BATSE TTE data type completely included the initial spike: Their spectral lags measured between the 25-50 keV and 100-300 energy ranges are consistent with zero in 90-95% of the cases, with most outliers probably representing the tail of the long burst class. We also analyze a small sample of "short" BATSE bursts - those with the most fluent, intense extended emission. The same lack of evolution on the pulse timescale obtains for the extended emission in the brighter bursts where significant measurements can be made. One possible inference is that both emission components may arise in the same region. We also show that the dynamic range in the ratio of peak intensities, spike : extended, is at least approx. l0(exp 3), and that for some bursts, the extended emission is only a factor of 2-5 lower. However, for our whole sample the total counts fluence of the extended component equals or exceeds that in the spike by a factor of several.

  3. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2008-01-01

    Gamma-ray bursts (GRBs) are among the most fascinating occurrences in the universe. They are powerful explosions, visible to high redshift, and thought to be the signature of black hole formation. The Swift Observatory has been detecting 100 bursts per year for 3 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from approximately 1 minute after the burst, continuing for days. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type II and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are providing a new tool to study the high redshift universe. Swift has detected several events at z greater than 5 and one at z=6.3 giving metallicity measurements and other data on galaxies at previously inaccessible distances. The talk will present the latest results from Swift in GRB astronomy.

  4. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2009-01-01

    Gamma-ray bursts (GRBs) are among the most fascinating occurrences in the universe. They are powerful explosions, visible to high redshift, and thought to be the signature of black hole formation. The Swift Observatory has been detecting 100 bursts per year for 4 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from approximately 1 minute after the burst, continuing for days. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type II and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are providing a new tool to study the high redshift universe. Swift has detected several events at z>5 and one at z=6.7 giving metallicity measurements and other data on galaxies at previously inaccessible distances. The talk will present the latest results from Swift in GRB astronomy.

  5. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2008-01-01

    Gamma-ray bursts (GRBs) are among the most fascinating occurrences in the universe. They are powerful explosions, visible to high redshift, and thought to be the signature of black hole formation. The Swift Observatory has been detecting 100 bursts per year for 3 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from - 1 minute after the burst, continuing for days. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type I1 and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are providing a new tool to study the high redshift universe. Swift has detected several events at z>5 and one at z=6.3 giving metallicity measurements and other data on galaxies at previously inaccessible distances. The talk will present the latest results from Swift in GRB astronomy.

  6. Data Fusion for Gamma-Ray Burst Population Studies

    NASA Astrophysics Data System (ADS)

    Loredo, Thomas; Wasserman, I.

    2006-09-01

    Gamma-ray burst (GRB) data are heterogeneous. Survey missions such as CGRO and Swift provide basic information (e.g., direction, peak flux) for all bursts. But for a subset of bursts with counterparts at other wavelengths, other data is available from afterglow observations, e.g., host galaxy redshifts, isotropic energy, and afterglow light curves. This heterogeniety significantly complicates global (population-level) analyses. We have developed a "data fusion" methodology that can rigorously combine GRB data from various sources, making optimum use of all the information available. We build upon our earlier Bayesian/likelihood approach for analyzing GRB population data, which is ideally suited to data fusion. We are initially focusing our efforts on methods for analysis of models for the GRB spatial and luminosity distributions using burst intensity and redshift data (possibly including redshifts from "luminosity indicators"). Roughly speaking, our approach uses the supplementary data available for the subset of bursts with afterglows to approximately "calibrate" the more widely available burst intensity data. This allows more accurate modelling of the burster redshift and luminosity distributions. Our approach accounts for significant biases and distortions ignored in other current analyses.

  7. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2009-01-01

    Gamma-ray bursts (GRBs) are among the most fascinating occurrences in the universe. They are powerful explosions, visible to high redshift, and thought to be the signature of black hole formation. The Swift Observatory has been detecting 100 bursts per year for 4 years and has greatly stimulated the field with new findings. Observations are made of the X-ray and optical afterglow from approximately 1 minute after the burst, continuing for days. Evidence is building that the long and short duration subcategories of GRBs have very different origins: massive star core collapse to a black hole for long bursts and binary neutron star coalescence to a black hole for short bursts. The similarity to Type II and Ia supernovae originating from young and old stellar progenitors is striking. Bursts are providing a new tool to study the high redshift universe. Swift has detected several events at z>5 and one at z=6.7 giving metallicity measurements and other data on galaxies at previously inaccessible distances. The talk will present the latest results from Swift in GRB astronomy.

  8. THRESHOLD FOR EXTENDED EMISSION IN SHORT GAMMA-RAY BURSTS

    SciTech Connect

    Norris, Jay P.; Gehrels, Neil

    2010-07-01

    The initial pulse complex (IPC) in short gamma-ray bursts is sometimes accompanied by a softer, low-intensity extended emission (EE) component. In cases where such a component is not observed, it is not clear if it is present but below the detection threshold. Using Bayesian Block (BB) methods, we measure the EE component and show that it is present in one-quarter of a Swift/BAT sample of 51 short bursts, as was found for the Compton/BATSE sample. We simulate bursts with EE to calibrate the BAT threshold for EE detection and show that this component would have been detected in nearly half of BAT short bursts if it were present, to intensities {approx}10{sup -2} counts cm{sup -2} s{sup -1}, a factor of 5 lower than actually observed in short bursts. In the BAT sample, the ratio of average EE intensity to IPC peak intensity, R{sub int}, ranges over a factor of 25, R{sub int} {approx} 3 x 10{sup -3} to 8 x 10{sup -2}. In comparison, for the average of the 39 bursts without an EE component, the 2{sigma} upper limit is R{sub int} < 8 x 10{sup -4}. These results suggest that a physical threshold effect operates near R{sub int} {approx} few x 10{sup -3} below which the EE component is not manifest.

  9. Gamma-ray-burst beaming and gravitational-wave observations.

    PubMed

    Chen, Hsin-Yu; Holz, Daniel E

    2013-11-01

    Using the observed rate of short-duration gamma-ray bursts (GRBs) it is possible to make predictions for the detectable rate of compact binary coalescences in gravitational-wave detectors. We show that the nondetection of mergers in the existing LIGO/Virgo data constrains the beaming angles and progenitor masses of gamma-ray bursts, although these limits are fully consistent with existing expectations. We make predictions for the rate of events in future networks of gravitational-wave observatories, finding that the first detection of a neutron-star-neutron-star binary coalescence associated with the progenitors of short GRBs is likely to happen within the first 16 months of observation, even in the case of only two observatories (e.g., LIGO-Hanford and LIGO-Livingston) operating at intermediate sensitivities (e.g., advanced LIGO design sensitivity, but without signal recycling mirrors), and assuming a conservative distribution of beaming angles (e.g., all GRBs beamed within θ(j) = 30°). Less conservative assumptions reduce the waiting time until first detection to a period of weeks to months, with an event detection rate of >/~10/yr. Alternatively, the compact binary coalescence model of short GRBs can be ruled out if a binary is not seen within the first two years of operation of a LIGO-Hanford, LIGO-Livingston, and Virgo network at advanced design sensitivity. We also demonstrate that the gravitational wave detection rate of GRB triggered sources (i.e., those seen first in gamma rays) is lower than the rate of untriggered events (i.e., those seen only in gravitational waves) if θ(j)≲30°, independent of the noise curve, network configuration, and observed GRB rate. The first detection in gravitational waves of a binary GRB progenitor is therefore unlikely to be associated with the observation of a GRB.

  10. EGRET detection of high energy gamma rays from the gamma-ray burst of 3 May 1991

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1992-01-01

    On May 3, 1991, the Energetic Gamma Ray Experiment Telescope on the Compton Gamma Ray Observatory detected a gamma-ray burst both in the energy measurement subsystem and independently in the spark chamber assembly. Six individual photons were detected in the spark chamber, allowing a determination of the burst arrival direction which was l(II) = 171.9 deg +/- 1.3 deg, b(II) = 5.3 deg +/- 1.1 deg. Three energy spectra were measured from 1 to 200 MeV; they were measured during the first second after the Burst and Transient Sources Experiment trigger, the next two seconds, and the subsequent four seconds. The first two spectra exhibit a similar differential spectra index of about -2.2 with no apparent high-energy cut-off. By the time of the third spectrum, an additional soft component is evident.

  11. Understanding soft gamma-ray repeaters in the context of the extragalactic radio pulsar origin of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Melia, Fulvio; Fatuzzo, Marco

    1993-01-01

    Gamma-ray burst (GRB) sources and soft gamma-ray repeaters (SGRs) may be neutron stars undergoing structural adjustments that produce transient gamma-ray events. A unified scenario is proposed in which young radio pulsars are responsible for SGRs and classical GRB sources. The radiative emission associated with a pulsar 'glitch' is seen as a GRB or an SGR event depending on the direction of our line of sight. Burst spectra, energetics, and statistics of GRBs and SGRs are discussed. It is shown that classical GRB spectra arise from Compton upscattering by charges accelerated along the viewing direction and SGR burst spectra are due to the thermalization of Alfven wave energy away from this direction. If crustal adjustments occur within the first 50,000 years of a pulsar's lifetime, the model predicts two SGR sources within the galaxy, in agreement with current observations.

  12. EGRET detection of high energy gamma rays from the gamma-ray burst of 3 May 1991

    NASA Technical Reports Server (NTRS)

    Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1992-01-01

    On May 3, 1991, the Energetic Gamma Ray Experiment Telescope on the Compton Gamma Ray Observatory detected a gamma-ray burst both in the energy measurement subsystem and independently in the spark chamber assembly. Six individual photons were detected in the spark chamber, allowing a determination of the burst arrival direction which was l(II) = 171.9 deg +/- 1.3 deg, b(II) = 5.3 deg +/- 1.1 deg. Three energy spectra were measured from 1 to 200 MeV; they were measured during the first second after the Burst and Transient Sources Experiment trigger, the next two seconds, and the subsequent four seconds. The first two spectra exhibit a similar differential spectra index of about -2.2 with no apparent high-energy cut-off. By the time of the third spectrum, an additional soft component is evident.

  13. Gamma ray bursts: A review of recent high-precision measurements

    NASA Technical Reports Server (NTRS)

    Cline, T. L.

    1981-01-01

    Recent measurements and discoveries in gamma ray bursts and transients are reviewed including observations of the red shifted annihilation line in two kinds of slow transients (in 'classical' gamma ray bursts and in the unique 1979 March 5th event); of red shifted nuclear lines in a slow transient and in one gamma ray burst; and of the positions of precise source locations of gamma ray bursts and of the March 5th event, within the supernova remnant N49 in the Large Magellanic Cloud.

  14. Statistical properties of the time histories of cosmic gamma-ray bursts detected by the BATSE experiment of the Compton gamma-ray observatory

    NASA Technical Reports Server (NTRS)

    Sagdeev, Roald

    1995-01-01

    The main scientific objectives of the project were: (1) Calculation of average time history for different subsets of BATSE gamma-ray bursts; (2) Comparison of averaged parameters and averaged time history for different Burst And Transient Source Experiments (BASTE) Gamma Ray Bursts (GRB's) sets; (3) Comparison of results obtained with BATSE data with those obtained with APEX experiment at PHOBOS mission; and (4) Use the results of (1)-(3) to compare current models of gamma-ray bursts sources.

  15. Radiative striped wind model for gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Bégué, D.; Pe'er, A.; Lyubarsky, Y.

    2017-05-01

    In this paper, we revisit the striped wind model in which the wind is accelerated by magnetic reconnection. In our treatment, radiation is included as an independent component, and two scenarios are considered. In the first one, radiation cannot stream efficiently through the reconnection layer, while the second scenario assumes that radiation is homogeneous in the striped wind. We show how these two assumptions affect the dynamics. In particular, we find that the asymptotic radial evolution of the Lorentz factor is not strongly modified whether radiation can stream through the reconnection layer or not. On the other hand, we show that the width, density and temperature of the reconnection layer are strongly dependent on these assumptions. We then apply the model to the gamma-ray burst context and find that photons cannot diffuse efficiently through the reconnection layer below radius r_D^{Δ } ˜ 10^{10.5} cm, which is about an order of magnitude below the photospheric radius. Above r_D^{Δ }, the dynamics asymptotes to the solution of the scenario in which radiation can stream through the reconnection layer. As a result, the density of the current sheet increases sharply, providing efficient photon production by the Bremsstrahlung process that could have profound influence on the emerging spectrum. This effect might provide a solution to the soft photon problem in gamma-ray bursts.

  16. The ionosphere as a gamma ray burst detector

    NASA Technical Reports Server (NTRS)

    Mcgruder, Charles H., III

    1992-01-01

    Unlike all man made detectors, which are only sensitive to relative narrow regions of the electromagnetic spectrum, the ionosphere is practically a perfect detector for high energy radiation because it absorbs all radiation from the far-ultraviolet to the higher energy gamma-rays. Therefore, it may be possible to employ the terrestrial atmosphere as a detector of high energy celestial photons. As early as the 1940's solar flares were detected by the disturbance they caused to the ionosphere. The VLF (3 - 30 kHz) approach for detecting ionospheric disturbances is based on the following physical circumstance: celestial high energy radiation ionizes the atoms of the earth's ionosphere leading to the production of free electrons. These free electrons influence the propagation of electromagnetic waves. By studying the phase and amplitude changes of VLF radio wave propagating in the earth-ionosphere waveguide, it was hoped to ascertain the electron density in these regions and draw conclusions about the celestial radiation which caused them. To detect gamma-ray bursts, two conditions for the optimal detection are: (1) large zenith angle; and (2) alignment of burst and propagation path.

  17. Magnetic photon splitting and gamma ray burst spectra

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.

    1992-01-01

    The splitting of photons into two photons becomes both possible and significant in magnetic fields in excess of 10(exp 12) Gauss. Below the threshold energy, 2m sub e c(exp 2) for single photon pair production, splitting can be an astronomically observable phenomenon evident in gamma ray burst spectra. In such circumstances, it was found that magnetic photon splitting reprocesses the gamma ray burst continuum by degrading the photon energy, with a net effect that is quite similar to pair cascade reprocessing of the spectrum. Results are presented for the spectral modifications due to splitting, taking into account the different probabilities for splitting for different polarization modes. Unpolarized and polarized pair cascade photon spectra form the input spectra for the model, which calculates the resulting splitting reprocessed spectra numerically by solving the photon kinetic equations for each polarization mode. This inclusion of photon polarizations is found to not alter previous predictions that splitting produce a significant flattening of the hard X ray continuum and a bump at MeV energies below a pair production turnover. The spectrum near the bump is always strongly polarized.

  18. FLARES IN LONG AND SHORT GAMMA-RAY BURSTS

    SciTech Connect

    Dado, Shlomo; Dar, Arnon E-mail: arnon@physics.technion.ac.i

    2010-04-01

    The many similarities between the prompt emission pulses in gamma-ray bursts (GRBs) and X-ray flares during the fast decay and afterglow (AG) phases of GRBs suggest a common origin. In the cannonball (CB) model of GRBs, this common origin is mass accretion episodes of fall-back matter on a newly born compact object. The prompt emission pulses are produced by a bipolar jet of highly relativistic plasmoids (CBs) ejected in the early, major episodes of mass accretion. As the accretion material is consumed, one may expect the engine's activity to weaken. X-ray flares ending the prompt emission and during the AG phase are produced in such delayed episodes of mass accretion. The common engine, environment, and radiation mechanisms (inverse Compton scattering and synchrotron radiation) produce their observed similarities. Flares in both long GRBs and short hard gamma-ray bursts (SHBs) can also be produced by bipolar ejections of CBs following a phase transition in compact objects due to loss of angular momentum and/or cooling. Optical flares, however, are mostly produced in collisions of CBs with massive stellar winds/ejecta or with density bumps along their path. In this paper, we show that the master formulae of the CB model of GRBs and SHBs, which reproduce very well their prompt emission pulses and their smooth AGs, seem to reproduce also very well the light curves and spectral evolution of the prominent X-ray and optical flares that are well sampled.

  19. Flares in Long and Short Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon

    2010-04-01

    The many similarities between the prompt emission pulses in gamma-ray bursts (GRBs) and X-ray flares during the fast decay and afterglow (AG) phases of GRBs suggest a common origin. In the cannonball (CB) model of GRBs, this common origin is mass accretion episodes of fall-back matter on a newly born compact object. The prompt emission pulses are produced by a bipolar jet of highly relativistic plasmoids (CBs) ejected in the early, major episodes of mass accretion. As the accretion material is consumed, one may expect the engine's activity to weaken. X-ray flares ending the prompt emission and during the AG phase are produced in such delayed episodes of mass accretion. The common engine, environment, and radiation mechanisms (inverse Compton scattering and synchrotron radiation) produce their observed similarities. Flares in both long GRBs and short hard gamma-ray bursts (SHBs) can also be produced by bipolar ejections of CBs following a phase transition in compact objects due to loss of angular momentum and/or cooling. Optical flares, however, are mostly produced in collisions of CBs with massive stellar winds/ejecta or with density bumps along their path. In this paper, we show that the master formulae of the CB model of GRBs and SHBs, which reproduce very well their prompt emission pulses and their smooth AGs, seem to reproduce also very well the light curves and spectral evolution of the prominent X-ray and optical flares that are well sampled.

  20. VHE-UHE Properties of Gamma Ray Bursts

    SciTech Connect

    Measzaros, P.

    2008-12-24

    Gamma-ray bursts are observed to emit at least up to GeV energies, and their photon spectrum at the source is expected to extend up to TeV, due to either or both leptonic and hadronic mechanisms. I review some recent developments in GRB phenomenology in the light of Swift and other sub-MeV measurement, as well as recent theoretical work. I discuss then the acceleration of cosmic rays in GRB, which can extend to GZK energies, and the possibility of acceleration in GRB-related or other hypernovae. In both, synchrotron and inverse Compton, as well as hadronic processes, can lead to GeV-TeV gamma-rays measurable by GLAST, AGILE, or ACTs, providing useful probes of the burst physics and model parameters. Photo-meson and pp interactions also produce neutrinos at energies ranging from sub-TeV to EeV, which are targets for experiments such as IceCube, ANITA and KM3NeT.

  1. Predicting supernova associated to gamma-ray burst 130427a

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  2. Measuring Cosmological Parameters with Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Amati, Lorenzo; Valle, Massimo Della

    2015-01-01

    Gamma-Ray Bursts (GRB) emit in a few dozen of seconds up to ~1054 erg, in terms of isotropic equivalent radiated energy Eiso, therefore they can be observed up to z ~ 10 and appear very promising tools to describe the expansion rate history of the Universe. In this paper we review the use of the Ep,i-Eiso correlation of Gamma-Ray Bursts to measure ΩM. We show that the present data set of GRBs, coupled with the assumption that we live in a flat universe, can provide indipendent evidence, from other probes, that ΩM~0.3. We show that current (e.g., Swift, Fermi/GBM, Konus-WIND) and next GRB experiments (e.g., CALET/GBM, SVOM, Lomonosov/UFFO, LOFT/WFM) will allow us, within a few years, to constrain ΩM and the evolution of dark energy with time, with an accuracy comparable to that currently exhibited by SNe-Ia.

  3. Neutrino emission from gamma-ray burst fireballs, revised.

    PubMed

    Hümmer, Svenja; Baerwald, Philipp; Winter, Walter

    2012-06-08

    We review the neutrino flux from gamma-ray bursts, which is estimated from gamma-ray observations and used for the interpretation of recent IceCube data, from a particle physics perspective. We numerically calculate the neutrino flux for the same astrophysical assumptions as the analytical fireball neutrino model, including the dominant pion and kaon production modes, flavor mixing, and magnetic field effects on the secondary muons, pions, and kaons. We demonstrate that taking into account the full energy dependencies of all spectra, the normalization of the expected neutrino flux reduces by about one order of magnitude and the spectrum shifts to higher energies, where we can pin down the exact origin of the discrepancies by the recomputation of the analytical models. We also reproduce the IceCube-40 analysis for exactly the same bursts and same assumptions and illustrate the impact of uncertainties. We conclude that the baryonic loading of the fireballs, which is an important control parameter for the emission of cosmic rays, can be constrained significantly with the full-scale experiment after about ten years.

  4. Gamma-Ray Bursts, Collisionless Shocks and Synthetic Spectra

    NASA Astrophysics Data System (ADS)

    Hededal, Christian

    2005-06-01

    The radiation from afterglows of gamma-ray bursts (GRB) is generated in collisionless plasma shocks. The two main ingredients behind the radiation are high-energy, non-thermal electrons and a strong magnetic field. I argue that in order to make the right conclusions about gamma-ray burst and afterglow parameters from observations, it is crucial to have a firm understanding of the microphysics of collisionless shock. I present the results of self-consistent, three-dimensional particle-in-cell computational simulations of the collision of weakly magnetized plasma shells: The experiments show how a plasma instability generates a magnetic field in the shock. The field has strength up to percents of the equipartition value. The experiments also reveal a new, non-thermal electron acceleration mechanism that differs substantially from Fermi acceleration. Finally, I present the results from a new numerical tool that enables us to extract synthetic radiation spectra directly from the experiments. The preliminary results differ from synchrotron radiation but are consistent with GRB afterglow observations. I conclude that strong magnetic field generation, non-thermal particle acceleration and the emission of radiation that is consistent with GRB afterglow observations, are all unavoidable consequences of the collision between two relativistic plasma shells.

  5. Host galaxies are the obscurers of Gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Buchner, Johannes; Schulze, Steve; Bauer, Franz E.

    2017-08-01

    The luminous, high-energy emission of gamma-ray bursts (GRBs) makes them efficient probes of the high-redshift universe. The origin of the obscuration of gamma-ray burst afterglow is still unclear. We study the afterglows metal column densities along the line-of-sight of all Swift-detected long GRBs with an improved hierarchical Bayesian analysis methodology. We characterise follow-up biases and side-step them using SHOALS, an unbiased sub-sample with highly complete follow-up. That survey also measures Spitzer host masses. Overall, the column densities shows little redshift evolution but a significant correlation with host stellar mass. A simple geometrical model explains the width and shape of the column density distribution and the trend with galaxy mass correlation. Our findings implicate the host's galaxy-scale metal gas as the dominant obscurer. From a galaxy evolution perspective, our study places new constraints on the metal gas mass inside galaxies at z=0.5-4. We compare these with modern cosmological simulations (Illustris and EAGLE) and discuss implications for the obscuration of other sources inside high redshift galaxies, such as active galactic nuclei.

  6. Gamma-ray bursts appear simpler than expected?

    NASA Astrophysics Data System (ADS)

    Chardonnet, P.; Filina, A. A.; Popov, M. V.; Chechetkin, V. M.; Baranov, A. A.

    The cosmic gamma-ray bursts are certainly an enigma in astrophysics. The "standard fireball" scenario developed during many years has provided a possible explanation of this phenomenon. The aim of this work is simply to explore a new possible interpretation by developing a coherent scenario inside the global picture of stellar evolution. At the basis of our scenario is the fact that maybe we have not fully understood how the core of a pair instability supernovae explode. In such a way, we have proposed a new paradigm assuming that the core of such massive star, instead of doing a symmetrical explosion, is completely fragmented in hot spots of burning nuclear matter. We have tested our scenario using some observational data like GRB spectrum, light curves, Amati relation and GRB-SN connection, and for each set of data we have proposed a possible physical interpretation. We have also suggested some possible tests of this scenario by measurement at high redshift. If this scenario is correct, it tells us simply that cosmic gamma-ray bursts are simply a missing link in stellar evolution.

  7. Effects of Goldstone bosons on gamma-ray bursts

    SciTech Connect

    Tu, Huitzu; Ng, Kin-Wang E-mail: nkw@phys.sinica.edu.tw

    2016-03-01

    Gamma-ray bursts (GRBs) are the most energetic explosion events in the universe. An amount of gravitational energy of the order of the rest-mass energy of the Sun is released from a small region within a short time. This should lead to the formation of a fireball of temperature in the MeV range, consisting of electrons/positrons, photons, and a small fraction of baryons. We exploit the potential of GRB fireballs for being a laboratory for testing particle physics beyond the Standard Model, where we find that Weinberg's Higgs portal model serves as a good candidate for this purpose. Due to the resonance effects, the Goldstone bosons can be rapidly produced by electron-positron annihilation process in the initial fireballs of the gamma-ray bursts. On the other hand, the mean free path of the Goldstone bosons is larger than the size of the GRB initial fireballs, so they are not coupled to the GRB's relativistic flow and can lead to significant energy loss. Using generic values for the GRB initial fireball energy, temperature, radius, expansion rate, and baryon number density, we find that the GRB bounds on the parameters of Weinberg's Higgs portal model are indeed competitive to current laboratory constraints.

  8. GRO: Black hole models for gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Ruderman, Malvin

    1995-01-01

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

  9. Cosmological Gamma-Ray Bursts and Hypernovae Conclusively Linked

    NASA Astrophysics Data System (ADS)

    2003-06-01

    Clearest-Ever Evidence from VLT Spectra of Powerful Event Summary A very bright burst of gamma-rays was observed on March 29, 2003 by NASA's High Energy Transient Explorer (HETE-II) , in a sky region within the constellation Leo. Within 90 min, a new, very bright light source (the "optical afterglow") was detected in the same direction by means of a 40-inch telescope at the Siding Spring Observatory (Australia) and also in Japan. The gamma-ray burst was designated GRB 030329 , according to the date. And within 24 hours, a first, very detailed spectrum of this new object was obtained by the UVES high-dispersion spectrograph on the 8.2-m VLT KUEYEN telescope at the ESO Paranal Observatory (Chile). It allowed to determine the distance as about 2,650 million light-years (redshift 0.1685). Continued observations with the FORS1 and FORS2 multi-mode instruments on the VLT during the following month allowed an international team of astronomers [1] to document in unprecedented detail the changes in the spectrum of the optical afterglow of this gamma-ray burst . Their detailed report appears in the June 19 issue of the research journal "Nature". The spectra show the gradual and clear emergence of a supernova spectrum of the most energetic class known, a "hypernova" . This is caused by the explosion of a very heavy star - presumably over 25 times heavier than the Sun. The measured expansion velocity (in excess of 30,000 km/sec) and the total energy released were exceptionally high, even within the elect hypernova class. From a comparison with more nearby hypernovae, the astronomers are able to fix with good accuracy the moment of the stellar explosion. It turns out to be within an interval of plus/minus two days of the gamma-ray burst. This unique conclusion provides compelling evidence that the two events are directly connected. These observations therefore indicate a common physical process behind the hypernova explosion and the associated emission of strong gamma-ray

  10. Location of the 1979 April 6 gamma-ray burst

    NASA Technical Reports Server (NTRS)

    Laros, J. G.; Evans, W. D.; Fenimore, E. E.; Klebesadel, R. W.; Barat, C.; Hurley, K.; Niel, M.; Vedrenne, G.; Estulin, I. V.; Zenchenko, V. M.

    1981-01-01

    A gamma-ray burst was recorded on 1979 April 6 at 1140 UT by instruments on the Pioneer Venus Orbiter (PVO), Venera 11 (V11), Venera 12 (V12), Prognoz 7 (P7), and International Sun-Earth Explorer-3 (ISEE-3) spacecraft. The event consisted of a single spike of 0.2 s duration and had a spectral feature near 400 keV, thus resembling the 1979 March 5 event in two respects. However, important differences in rise time and spectral hardness make it impossible to conclude positively that the two events shared the same mechanism or had comparable energetics. Constraints placed by these findings on the energetics and types of objects that could be responsible for the April 6 and possibly the March 5 bursts are discussed.

  11. Null Result in gamma-ray burst lensed echo search

    NASA Technical Reports Server (NTRS)

    Nemiroff, R. J.; Wickramasinghe, W. A. D. T.; Norris, J. P.; Kouveliotou, C.; Fishman, G. J.; Meegan, C. A.; Paciesas, W. S.; Horack, J.

    1994-01-01

    We have searched for gravitational-lens-induced echoes between gamma-ray bursts (GRBs) in Burst and Transient Source Experiment (BATSE) data. The search was conducted in two phases. In the first phase we compared all GRBs in a brightness-complete sample of the first 260 GRBs with recorded angular positions having at least a 5% chance of being coincident from their combined positional error. In the second phase, we compared all GRB light curves of the first 611 GRBs with recorded angular positions having at least a 55% chance of being coincident from their combined positional error. No unambiguous gravitational lens candidate pairs were found in either phase, although a 'library of close calls' was accumulated for future reference. This result neither excludes nor significantly constrains a cosmological origin for GRBs.

  12. The Prompt and High Energy Emission of Gamma Ray Bursts

    SciTech Connect

    Meszaros, P.

    2009-05-25

    I discuss some recent developments concerning the prompt emission of gamma-ray bursts, in particular the jet properties and radiation mechanisms, as exemplified by the naked-eye burst GRB 080319b, and the prompt X-ray emission of XRB080109/SN2008d, where the progenitor has, for the first time, been shown to contribute to the prompt emission. I discuss then some recent theoretical calculations of the GeV/TeV spectrum of GRB in the context of both leptonic SSC models and hadronic models. The recent observations by the Fermi satellite of GRB 080916C are then reviewed, and their implications for such models are discussed, together with its interesting determination of a bulk Lorentz factor, and the highest lower limit on the quantum gravity energy scale so far.

  13. Recent DMSP satellite detections of gamma-ray bursts

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R.W.; Griffee, J.W.

    1998-05-01

    Gamma-ray burst detectors are aboard seven U.S. Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, two of which are currently in use. Their 800 km altitude orbits give a field of view to 117 degrees from the zenith. A great many bursts have been detected, usually in coincidence with detections by GRO or other satellites such as PVO or Ulysses. The directions of the sources can be determined with considerable accuracy from such correlated observations, even when neither GRO nor BeppoSAX is involved. Results obtained from the most recently launched satellites (DMSP 13 and DMSP 14) are given in this paper. {copyright} {ital 1998 American Institute of Physics.}

  14. An analysis of gamma ray burst time histories

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick; Karr, Gerald R.

    1994-01-01

    Gamma ray burst time histories, ranging in durations from milliseconds to thousands of seconds, are as varied as the number of bursts. They show a wide array of structures from those that are very smooth to those that contain a seemingly uncountable number of spikes riding on top of other spikes. These profiles have tantalized researchers for years - they obviously hold important information on the nature of GRB's, but to date no one has been successful in analyzing them. For the past year the author has been working on algorithms to analyze these data. Two approaches have been followed in this investigation. The first is an attempt to quantify the amount of structure, or spikiness, in a profile. The second involves applying the latest theorems on chaos and fractals with the aim of extracting useful information from what seems to be a random collection of shot noise.

  15. Cyclotron resonant scattering and absorption. [in gamma ray bursts

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.; Daugherty, Joseph K.

    1991-01-01

    The relativistic cross-sections for first-order absorption and second-order scattering are compared to determine the conditions under which the absorption cross-section is a good approximation to the much more complex scattering cross-section for purposes of modeling cyclotron lines in gamma-ray bursts. Differences in both the cross-sections and the line profiles are presented for a range of field strengths, angles, and electron temperatures. The relative difference of the cross-sections at one line width from resonance was found to increase with field strength and harmonic number. The difference is also strongly dependent on the photon angle to the magnetic field. For the field strength, 1.7 x 10 to the 12th G, and the angle inferred from the Ginga burst features, absorption is an excellent approximation for the profiles at the first and second harmonics.

  16. On the future of gamma-ray burst cosmology

    NASA Astrophysics Data System (ADS)

    Mörtsell, E.; Sollerman, J.

    2005-06-01

    With the understanding that the enigmatic gamma-ray bursts (GRBs) are beamed explosions, and with the recently discovered 'Ghirlanda relation', the dream of using GRBs as cosmological yardsticks may have come a few steps closer to reality. Assuming that the Ghirlanda relation is real, we have investigated possible constraints on cosmological parameters using a simulated future sample of a large number of GRBs inspired by the ongoing SWIFT mission. Comparing with constraints from a future sample of Type Ia supernovae, we find that GRBs are not efficient in constraining the amount of dark energy or its equation of state. The main reason for this is that very few bursts are available at low redshifts.

  17. Models for Supernovae and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Woosley, Stan

    Supernovae and gamma-ray bursts are the brightest stellar mass explosions in the universe. As such, they serve as cosmic beacons for probing cosmic structure and diagnosing the properties of stars and the universe when it was young. They also produce black holes and neutron stars, interesting in themselves as laboratories where exotic physics comes into play, and they make the elements from which life arises. Consequently, supernovae and gamma-ray bursts are subject to intense study by many NASA missions. We propose focused studies in five areas of supernova research that are directly relevant to NASA's missions, especially SWIFT, HST, JWST, and planning for WFIRST. Our specific topics are a) models for Type Ia supernovae; b) extreme supernovae and first supernovae; c) magnetar-powered supernovae; d) ultra-long duration gamma-ray bursts; and e) shock breakout in supernovae. These phenomena all have in common their importance to NASA missions and the fact that they can be studied using similar tools - computer codes that do radiation hydrodynamics. Our two principal codes, KEPLER (one-dimension) and CASTRO (one to three dimensions), have been honed to the task by years of supernova modeling, and have some unique capabilities. Type Ia supernovae have long been of interest to NASA, but their importance has increased lately because of their utility in determining cosmic distances and because a string of recent observational breakthroughs has severely limited their progenitors. Responding to these developments, we propose to focus on a class of model we have previously neglected, the merger of two white dwarfs. The mergers will be studied with KEPLER and CASTRO in one and two dimensions, and the spectra and light curves determined. The library of model results will be useful in interpreting the results of present NASA missions and planning new ones. A second important area of investigation will be the study of first generation stars and the supernovae that they produce

  18. Unraveling the Origin of Short Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Barthelmy, S. D.; Chincarini, G.; Burrows, D. N.; Gehrels, N.; Covino, S.; Moretti, A.; Romano, P.; OBrien, P. T.; Sarazin, C. L.; Kouveliotou, C.

    2005-01-01

    The origin of the short (<2 s) class of gamma-ray bursts (GRBs) is finally becoming clear after decades of search. The first one localized to a few arcseconds accuracy, GRB 050509B, was found to have a highly probable association with a nearby (z = 0.225) elliptical galaxy. A second one with arcsecond localization, GRB 050709, was also associated with a low redshift (z = 0.16) galaxy. We report here the detection of short GRB 050724 with remarkable properties; in particular, it has low energy gamma-ray emission that lasts for 100 s after the main short pulse, strong early X-ray afterglow, and an unusual lightcurve that rebrightens at 3x10(exp 4) s. A position on the sky accurate to 9 arcsec was determined and provided as a GCN alert to ground-based telescopes within 80 s. A subsequent high-resolution X-ray image provided a sub-arcsec position coincident with ground-based optical and radio observations of the afterglow. Like GRB 050509B, this burst is located off-center in an elliptical galaxy. The energy output of the GRB at the host distance of z = 0.258 is 2-3 orders of magnitude less than for long bursts. The low level of star formation in such galaxies is strong evidence against a collapsar or hypernova origin like that associated with long GRBs. Based on these new data, it is highly probable that short GRBs are produced by the coalescence of orbiting neutron stars (NSs) or black holes (BHs), with some evidence for a NS-BH merger in this burst.

  19. The First Swift BAT Gamma-Ray Burst Catalog

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

    We present the first Swift Burst Alert Telescope (BAT) catalog of gamma ray bursts (GRBs), which contains bursts detected by the BAT between 2004 December 19 and 2007 June 16. This catalog (hereafter BAT1 catalog) contains burst trigger time, location, 90% error radius, duration, fluence, peak flux, and time averaged spectral parameters for each of 237 GRBs, as measured by the BAT. The BAT-determined position reported here is within 1.75' of the Swift X-ray Telescope (XRT)-determined position for 90% of these GRBs. The BAT T(sub 90) and T(sub 50) durations peak at 80 and 20 seconds, respectively. From the fluence-fluence correlation, we conclude that about 60% of the observed peak energies, E(sup obs)(sub peak) of BAT GRBs could be less than 100 keV. We confirm that GRB fluence to hardness and GRB peak flux to hardness are correlated for BAT bursts in analogous ways to previous missions' results. The correlation between the photon index in a simple power-law model and E(sup obs)(sub peak) is also confirmed. We also report the current status for the on-orbit BAT calibrations based on observations of the Crab Nebula.

  20. Detection of gamma-ray bursts from Andromeda

    SciTech Connect

    Bulik, Tomasz; Coppi, Paolo S.; Lamb, Donald Q.

    1996-08-01

    If gamma-ray bursts originate in a corona around the Milky Way, it should also be possible to detect them from a similar corona around Andromeda. Adopting a simple model of high velocity neutron star corona, we evaluate the ability of instruments on existing missions to detect an excess of bursts toward Andromeda. We also calculate the optimal properties of an instrument designed to detect such an excess. We find that if the bursts radiate isotropically, an experiment with a sampling distance d{sub max} > or approx. 500 kpc could detect a significant excess of bursts in the direction of Andromeda in a few years of observation. If the radiation is beamed along the neutron star's direction of motion, an experiment with d{sub max} > or approx. 800 kpc would detect such an excess in a similar amount of time, provided that the width of the beam is greater than 10 deg. Lack of an excess toward Andromeda would therefore be compelling evidence that the bursts are cosmological in origin if made by an instrument at least 50 times more sensitive than BATSE, given current constraints on Galactic corona models. Comparisons with detailed dynamical calculations of the spatial distribution of high velocity neutron stars in the coronae around the Milky Way and Andromeda confirm these conclusions.

  1. An internally consistent gamma ray burst time history phenomenology

    NASA Technical Reports Server (NTRS)

    Cline, T. L.

    1985-01-01

    A phenomenology for gamma ray burst time histories is outlined. Order of their generally chaotic appearance is attempted, based on the speculation that any one burst event can be represented above 150 keV as a superposition of similarly shaped increases of varying intensity. The increases can generally overlap, however, confusing the picture, but a given event must at least exhibit its own limiting characteristic rise and decay times if the measurements are made with instruments having adequate temporal resolution. Most catalogued observations may be of doubtful or marginal utility to test this hypothesis, but some time histories from Helios-2, Pioneer Venus Orbiter and other instruments having one-to several-millisecond capabilities appear to provide consistency. Also, recent studies of temporally resolved Solar Maximum Mission burst energy spectra are entirely compatible with this picture. The phenomenology suggested here, if correct, may assist as an analytic tool for modelling of burst processes and possibly in the definition of burst source populations.

  2. ARE ULTRA-LONG GAMMA-RAY BURSTS DIFFERENT?

    SciTech Connect

    Boër, M.; Gendre, B.; Stratta, G.

    2015-02-10

    The discovery of a number of gamma-ray bursts (GRBs) with duration exceeding 1000 s has opened the debate on whether these bursts form a new class of sources, the so-called ultra-long GRBs, or if they are rather the tail of the distribution of the standard long GRB duration. Using the long GRB sample detected by Swift, we investigate the statistical properties of long GRBs and compare them with the ultra-long burst properties. We compute the burst duration of long GRBs using the start epoch of the so-called ''steep decay'' phase detected with Swift/XRT. We discuss also the differences observed in their spectral properties. We find that ultra-long GRBs are statistically different from the standard long GRBs with typical burst duration less than 100-500 s, for which a Wolf-Rayet star progenitor is usually invoked. Together with the presence of a thermal emission component we interpret this result as indication that the usual long GRB progenitor scenario cannot explain the extreme duration of ultra-long GRBs, their energetics, as well as the mass reservoir and size that can feed the central engine for such a long time.

  3. How Sample Completeness Affects Gamma-Ray Burst Classification

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Giblin, Timothy W.; Roiger, Richard J.; Haglin, David J.; Paciesas, William S.; Meegan, Charles A.

    2003-01-01

    Unsupervised pattern-recognition algorithms support the existence of three gamma-ray burst classes: class 1 (long, large-fluence bursts of intermediate spectral hardness), class 2 (short, small-fluence, hard bursts), and class 3 (soft bursts of intermediate durations and fluences). The algorithms surprisingly assign larger membership to class 3 than to either of the other two classes. A known systematic bias has been previously used to explain the existence of class 3 in terms of class 1 ; this bias allows the fluences and durations of some bursts to be underestimated, as recently shown by Hakkila et al. We show that this bias primarily affects only the longest bursts and cannot explain the bulk of the class 3 properties. We resolve the question of class 3's existence by demonstrating how samples obtained using standard trigger mechanisms fail to preserve the duration characteristics of small-peak flux bursts. Sample incompleteness is thus primarily responsible for the existence of class 3. In order to avoid this incompleteness, we show how a new, dual-timescale peak flux can be defined in terms of peak flux and fluence. The dual-timescale peak flux preserves the duration distribution of faint bursts and correlates better with spectral hardness (and presumably redshift) than either peak flux or fluence. The techniques presented here are generic and have applicability to the studies of other transient events. The results also indicate that pattern recognition algorithms are sensitive to sample completeness; this can influence the study of large astronomical databases, such as those found in a virtual observatory.

  4. Measurements of Gamma-Ray Bursts with Glast

    NASA Astrophysics Data System (ADS)

    Lichti, G. G.; Briggs, M.; Diehl, R.; Fishman, G.; Greiner, J.; Kippen, R. M.; Kouveliotou, C.; Meegan, C.; Paciesas, W.; Preece, R.; Schönfelder, V.; von Kienlin, A.

    One of the scientific goals of the main instrument of l GLAST is the study of gamma-ray bursts (GRBs) in the energy range from ˜20 MeV to ˜300 GeV. In order to extend the energy measurement towards lower energies, a secondary instrument, the l GLAST Burst Monitor (GBM), will measure GRBs from ˜10 keV to ˜25 MeV and will therefore allow the investigation of the relation between the keV and the MeV--GeV emission from GRBs over six energy decades. These unprecedented measurements will permit the exploration of the unknown aspects of the high-energy burst emission and the investigation of their connection with the well-studied low-energy emission. They will also provide new insights into the physics of GRBs in general. In addition, the excellent localization of GRBs by the Large-Area Telescope will stimulate follow-up observations at other wavelengths which may yield clues about the nature of the burst sources.

  5. Models for Gamma-Ray Bursts and Diverse Transients

    SciTech Connect

    Woosley, S.E.; Zhang, Weiqun; /KIPAC, Menlo Park

    2007-01-17

    The observational diversity of ''gamma-ray bursts'' (GRBs) has been increasing, and the natural inclination is a proliferation of models. We explore the possibility that at least part of this diversity is a consequence of a single basic model for the central engine operating in a massive star of variable mass, differential rotation rate, and mass loss rate. Whatever that central engine may be--and here the collapsar is used as a reference point--it must be capable of generating both a narrowly collimated, highly relativistic jet to make the GRB, and a wide angle, sub-relativistic outflow responsible for exploding the star and making the supernova bright. To some extent, the two components may vary independently, so it is possible to produce a variety of jet energies and supernova luminosities. We explore, in particular, the production of low energy bursts and find a lower limit, {approx} 10{sup 48} erg s{sup -1} to the power required for a jet to escape a massive star before that star either explodes or is accreted. Lower energy bursts and ''suffocated'' bursts may be particularly prevalent when the metallicity is high, i.e., in the modern universe at low redshift.

  6. An Analysis of Gamma-ray Burst Time Profiles from the Burst and Transient Source Experiment

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick

    1996-01-01

    This proposal requested funding to measure the durations of gamma-ray bursts (GRB) in the 4B catalog as well as to study the structure of GRB time profiles returned by the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory. The duration (T90) was to be measured using the same techniques and algorithms developed by the principal investigator for the 3B data. The profile structure studies fall into the two categories of variability and fractal analyses.

  7. 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.

  8. Earth Occultation Monitoring with the Fermi Gamma Ray Burst Monitor

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.

    2014-01-01

    Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique (EOT). Each time a source in our catalog is occulted by (or exits occultation by) the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors for daily monitoring. Light curves, updated daily, are available on our website http://heastro.phys.lsu.edu/gbm. Our software is also capable of performing the Earth occultation monitoring using up to 128 energy bands, or any combination of those bands, using our 128-channel, 4-s CSPEC data. The GBM BGO detectors, sensitive from about 200 keV to 40 keV, can also be used with this technique. In our standard application of the EOT, we use a catalog of sources to drive the measurements. To ensure that our catalog is complete, our team has developed an Earth occultation imaging method. In this talk, I will describe both techniques and the current data products available. I will highlight recent and important results from the GBM EOT, including the current status of our observations of hard X-ray variations in the Crab Nebula.

  9. Performance study of the gamma-ray bursts polarimeter POLAR

    NASA Astrophysics Data System (ADS)

    Sun, J. C.; Wu, B. B.; Bao, T. W.; Batsch, T.; Bernasconi, T.; Britvitch, I.; Cadoux, F.; Cernuda, I.; Chai, J. Y.; Dong, Y. W.; Gauvin, N.; Hajdas, W.; He, J. J.; Kole, M.; Kong, M. N.; Kong, S. W.; Lechanoine-Leluc, C.; Li, Lu; Liu, J. T.; Liu, X.; Marcinkowski, R.; Orsi, S.; Pohl, M.; Produit, N.; Rapin, D.; Rutczynska, A.; Rybka, D.; Shi, H. L.; Song, L. M.; Szabelski, J.; Wang, R. J.; Wen, X.; Xiao, H. L.; Xiong, S. L.; Xu, H. H.; Xu, M.; Zhang, L.; Zhang, L. Y.; Zhang, S. N.; Zhang, X. F.; Zhang, Y. J.; Zwolinska, A.

    2016-07-01

    The Gamma-ray Burst Polarimeter-POLAR is a highly sensitive detector which is dedicated to the measurement of GRB's polarization with a large effective detection area and a large field of view (FOV). The optimized performance of POLAR will contribute to the capture and measurement of the transient sources like GRBs and Solar Flares. The detection energy range of POLAR is 50 keV 500 keV, and mainly dominated by the Compton scattering effect. POLAR consists of 25 detector modular units (DMUs), and each DMU is composed of low Z material Plastic Scintillators (PS), multi-anode photomultipliers (MAPMT) and multi-channel ASIC Front-end Electronics (FEE). POLAR experiment is an international collaboration project involving China, Switzerland and Poland, and is expected to be launched in September in 2016 onboard the Chinese space laboratory "Tiangong-2 (TG-2)". With the efforts from the collaborations, POLAR has experienced the Demonstration Model (DM) phase, Engineering and Qualification Model (EQM) phase, Qualification Model (QM) phase, and now a full Flight Model (FM) of POLAR has been constructed. The FM of POLAR has passed the environmental acceptance tests (thermal cycling, vibration, shock and thermal vacuum tests) and experienced the calibration tests with both radioactive sources and 100% polarized Gamma-Ray beam at ESRF after its construction. The design of POLAR, Monte-Carlo simulation analysis, as well as the performance test results will all be introduced in this paper.

  10. Correlation Analysis of Prompt Emission from Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Pothapragada, Sriharsha

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

  11. UNCOVERING THE INTRINSIC VARIABILITY OF GAMMA-RAY BURSTS

    NASA Astrophysics Data System (ADS)

    Golkhou, V. Zach; Butler, Nathaniel R

    2014-08-01

    We develop a robust technique to determine the minimum variability timescale for gamma-ray burst (GRB) light curves, utilizing Haar wavelets. Our approach averages over the data for a given GRB, providing an aggregate measure of signal variation while also retaining sensitivity to narrow pulses within complicated time series. In contrast to previous studies using wavelets, which simply define the minimum timescale in reference to the measurement noise floor, our approach identifies the signature of temporally smooth features in the wavelet scaleogram and then additionally identifies a break in the scaleogram on longer timescales as a signature of a true, temporally unsmooth light curve feature or features. We apply our technique to the large sample of Swift GRB gamma-ray light curves and for the first time—due to the presence of a large number of GRBs with measured redshift—determine the distribution of minimum variability timescales in the source frame. We find a median minimum timescale for long-duration GRBs in the source frame of Δtmin = 0.5 s, with the shortest timescale found being on the order of 10 ms. This short timescale suggests a compact central engine (3000 km). We discuss further implications for the GRB fireball model and present a tantalizing correlation between the minimum timescale and redshift, which may in part be due to cosmological time dilation.

  12. 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.

  13. Cosmological Evolution and Distributions of Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Petrosian, Vahe

    2012-07-01

    Gamma-ray Bursts (GRBs), in virtue of their large redshifts are good candidates for the probe of the early universe, in particular the history of star formation and the build-up of the so-called metalicity. Moreover, discovery of a tight relation between a distance independent property (e.g photon energy or timescale) and a distance dependent one (e.g luminosity or emitted power) will allow one to use GRBs as "standard candles" for measurements of the global cosmological parameters. The achievement of these potentials requires determination of the distributions and cosmological evolutions of the relevant characteristics and the correlations between them. We have applied the non-parametric methods developed by Efron and Petrosian to GRB data from Swift and earlier satellites to determine the cosmological evolutions of the gamma-ray and X-ray luminosities, timescales and their formation rate. We also have determined the correlations between some of these quantities to test the possibility of using GRBs as standard candles. The results using the most current data will be presented. This work is done in collaboration with M. Dainotti, E. Kitanidis and D. Kocevski all at Stanford University.

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

    DOE PAGES

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

    2013-08-19

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

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

    SciTech Connect

    Atwood, W. B.; Baldini, L.; Bregeon, J.; Bruel, P.; Chekhtman, A.; Cohen-Tanugi, J.; Drlica-Wagner, A.; Granot, J.; Longo, F.; Omodei, Nicola; Pesce-Rollins, Melissa; Razzaque, S.; Rochester, L. S.; Sgrò, C.; Tinivella, M.; Usher, T. L.; Zimmer, S.

    2013-08-19

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

  16. NEW FERMI-LAT EVENT RECONSTRUCTION REVEALS MORE HIGH-ENERGY GAMMA RAYS FROM GAMMA-RAY BURSTS

    SciTech Connect

    Atwood, W. B.; Baldini, L.; Bregeon, J.; Pesce-Rollins, M.; Sgro, C.; Tinivella, M.; Bruel, P.; Cohen-Tanugi, J.; Granot, J.; Longo, F.; Razzaque, S.; Zimmer, S. E-mail: nicola.omodei@stanford.edu

    2013-09-01

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

  17. The low energy spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Bussard, R. W.; Lamb, F. K.

    1982-01-01

    The implications of observed gamma-ray burst spectra for the physical conditions and geometries of the sources are examined. It is noted that an explanation of the continua in terms of optically thin thermal bremsstrahlung requires a relatively large area but a fairly shallow depth. On the other hand, a spectrum similar to that observed could be produced by rapid flickering of sources with less extreme geometries if each flicker emits a Comptonized thermal spectrum. Either field inhomogeneities or plasma motions are required to interpret the low energy features as cyclotron extinction. An alternative explanation is photoelectric absorption by heavy atoms; this requires a field strength high enough to make one-photon electron positron annihilation possible. Observational tests of these possibilities are proposed

  18. The low energy spectra of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Bussard, R. W.; Lamb, F. K.

    1982-01-01

    The implications of observed gamma-ray burst spectra for the physical conditions and geometries of the sources are examined. It is noted that an explanation of the continua in terms of optically thin thermal bremsstrahlung requires a relatively large area but a fairly shallow depth. On the other hand, a spectrum similar to that observed could be produced by rapid flickering of sources with less extreme geometries if each flicker emits a Comptonized thermal spectrum. Either field inhomogeneities or plasma motions are required to interpret the low energy features as cyclotron extinction. An alternative explanation is photoelectric absorption by heavy atoms; this requires a field strength high enough to make one-photon electron positron annihilation possible. Observational tests of these possibilities are proposed

  19. Cosmic Evolution of Long Gamma-Ray Burst Luminosity

    NASA Astrophysics Data System (ADS)

    Liang, Enwei

    2015-08-01

    Gamma-ray bursts (GRBs) are detected in a broad redshift range. The cosmic evolution of GRB luminosity is essential for revealing the GRB physics and using GRBs as cosmological probes. We characterize the intrinsic cosmological evolution of long GRB luminosity as L=L0 (1+z)^k, and measure the k value with the non-parameterized tau statistics using a large and uniform sample of 231 redshift-known GRBs observed with Swift/BAT in 10 operation years. We find that the observed correlation between L and (1+z) is due to the observational selection effect and do not find robust evidence for intrinsic relation between L and (1+z) derived from current sample. In addition, we also confirm this result with simulations by assuming that the long GRB rate follows the star formation rate incorporating with cosmic metallicity history.

  20. Black Holes in Gamma Ray Bursts and Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Ruffini, Remo; Argüelles, C. R.; Fraga, B. M. O.; Geralico, A.; Quevedo, H.; Rueda, J. A.; Siutsou, I.

    2013-09-01

    Current research marks a clear success in identifying the moment of formation of a Black Hole of 10M⊙, with the emission of a Gamma Ray Burst. This explains in terms of the 'Blackholic Energy' the source of the energy of these astrophysical systems. Their energetics up to 1054 erg, make them detectable all over our Universe. Concurrently a new problematic has been arising related to: (a) The evidence of Dark Matter in galactic halos; (b) The origin of the Super Massive Black Holes in active galactic nuclei and Quasars and (c) The purported existence of a Black Hole in the Center of our Galaxy. These three aspects of this new problematic have been traditionally approached independently. We propose an unified approach to all three of them based on a system of massive self-gravitating neutrinos in General Relativity. Perspectives of future research are presented.

  1. Gamma ray bursts and extreme energy cosmic rays

    SciTech Connect

    Scarsi, Livio

    1998-06-15

    Extreme Energy Cosmic Ray particles (EECR) with E>10{sup 20} eV arriving on Earth with very low flux ({approx}1 particle/Km{sup 2}-1000yr) require for their investigation very large detecting areas, exceeding values of 1000 km{sup 2} sr. Projects with these dimensions are now being proposed: Ground Arrays ('Auger' with 2x3500 km{sup 2} sr) or exploiting the Earth Atmosphere as seen from space ('AIR WATCH' and OWL,'' with effective area reaching 1 million km{sup 2} sr). In this last case, by using as a target the 10{sup 13} tons of air viewed, also the high energy neutrino flux can be investigated conveniently. Gamma Rays Bursts are suggested as a possible source for EECR and the associated High Energy neutrino flux.

  2. The Quest for Short Gamma-ray Burst 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; Nardini, Marco

    2013-04-01

    Short Gamma-ray bursts (SGRBs) are the most elusive among GRBs with just a few of them having being studied pan- chromatically. Only two 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.

  3. The Quest for Short Gamma-ray Burst Radio Afterglows

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Short Gamma-ray bursts (SGRBs) are the most elusive among GRBs with just a few of them having being studied pan- chromatically. Only two 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.

  4. Gamma-Ray Bursts Shower the Universe with Metals

    SciTech Connect

    Hazi, A

    2006-01-13

    According to the results from a Livermore computer model, some of the small change jingling in your pocket contains zinc and copper created in massive gamma-ray bursts (GRBs) that rank as the most impressive light shows in the universe. Livermore astrophysicist Jason Pruet and his colleagues Rebecca Surman and Gail McLaughlin from North Carolina State University (NCSU) reported on their calculations in the February 20, 2004, issue of ''Astrophysical Journal Letters''. They found that GRBs from black holes surrounded by a disk of dense, hot plasma may have contributed heavily to the galactic inventory of elements such as calcium, scandium, titanium, zinc, and copper. ''A typical GRB of this kind briefly outshines all the stars in millions of galaxies combined'', says Pruet. ''Plus it makes about 100 times as much of some common elements as an ordinary supernova''.

  5. Gamma ray bursts as a signature for entangled gravitational systems

    NASA Astrophysics Data System (ADS)

    Basini, Giuseppe; Capozziello, Salvatore; Longo, Giuseppe

    2004-01-01

    Gamma ray bursts (GRBs), due to their features, can be considered not only extremely energetic, but also as the most relativistic astrophysical objects discovered. Their phenomenology is still matter of debate and, till now, no fully satisfactory model has been formulated to explain the nature of their origin. In the framework of a recently developed new theory, where general conservation laws are always and absolutely conserved in nature, we propose an alternative model where an ``entangled'' gravitational system, dynamically constituted by a black holes connected to a white hole through a worm hole, seems capable of explaining most of the properties inferred for the GRB engine. In particular, it leads to a natural explanation of energetics, beaming, polarization, and, very likely, distribution. On the other hand, GRBs can be considered a signature of such entangled gravitational systems.

  6. GRAVITATIONAL WAVES OF JET PRECESSION IN GAMMA-RAY BURSTS

    SciTech Connect

    Sun Mouyuan; Liu Tong; Gu Weimin; Lu Jufu

    2012-06-10

    The physical nature of gamma-ray bursts (GRBs) is believed to involve an ultra-relativistic jet. The observed complex structure of light curves motivates the idea of jet precession. In this work, we study the gravitational waves of jet precession based on neutrino-dominated accretion disks around black holes, which may account for the central engine of GRBs. In our model, the jet and the inner part of the disk may precess along with the black hole, which is driven by the outer part of the disk. Gravitational waves are therefore expected to be significant from this black-hole-inner-disk precession system. By comparing our numerical results with the sensitivity of some detectors, we find that it is possible for DECIGO and BBO to detect such gravitational waves, particularly for GRBs in the Local Group.

  7. Astrophysical High-Energy Neutrinos and Gamma-Ray Bursts

    SciTech Connect

    Murase, Kohta

    2008-10-22

    High-energy neutrinos from gamma-ray bursts (GRBs) have been expected in various scenarios. Many predictions for prompt and afterglow emission were done in the pre-Swift era. After the launch of Swift, several new discoveries such as flares have allowed us to expect additional new possibilities of high-energy neutrino emission from GRBs. In this paper, we overview various predictions of GRB neutrino emission, and discuss feature prospects. High-energy neutrino signals may be detected by future-coming large neutrino detectors such as IceCube and KM3Net. If detected, they should be very useful to know the nature of cosmic-ray acceleration sites. It would also help us to reveal the possible connection between ultra-high-energy cosmic rays (UHECRs) and GRBs. Finally, we also compare a prediction of GRB neutrinos with several predictions for other sources such as active galactic nuclei (AGN) and clusters of galaxies.

  8. Gamma-ray bursts and their use as cosmic probes.

    PubMed

    Schady, Patricia

    2017-07-01

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

  9. Gamma-ray bursts and their use as cosmic probes

    NASA Astrophysics Data System (ADS)

    Schady, Patricia

    2017-07-01

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

  10. High-z Universe with Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Kouveliotou, C.

    2011-01-01

    Gamma-Ray Bursts (GRBs) are the most luminous explosions in space and trace the cosmic star formation history back to the first generations of stars. Their bright afterglows allow us to trace the abundances of heavy elements to large distances, thereby measuring cosmic chemical evolution. To date GRBs have been detected up to distances of z=8.23 and possibly even beyond z9. This makes GRBs a unique and powerful tool to probe the high-z Universe up to the re-ionization era. We discuss the current status of the field, place it in context with other probes, and also discuss new mission concepts that have been planned to utilize GRBs as probes.

  11. Gamma-ray bursts from synchrotron self-Compton emission

    NASA Astrophysics Data System (ADS)

    Stern, Boris E.; Poutanen, Juri

    2004-08-01

    The emission mechanism of gamma-ray bursts (GRBs) is still a matter of debate. The standard synchrotron energy spectrum of cooling electrons FE~E-1/2 is much too soft to account for the majority of the observed spectral slopes. An alternative in the form of quasi-thermal Comptonization in a high-compactness source has difficulties in reproducing the peak of the observed photon distribution below a few hundred keV. We show here that for typical parameters expected in the GRB ejecta the observed spectra in the 20-1000 keV energy range can be produced by inverse Compton scattering of the synchrotron radiation in a partially self-absorbed regime. If the particles are continuously accelerated/heated over the lifetime of a source rather than being instantly injected, a prominent peak develops in their distribution at a Lorentz factor γ~ 30-100, where synchrotron and inverse-Compton losses are balanced by acceleration and heating due to synchrotron self-absorption. The synchrotron peak should be observed at 10-100 eV, whereas the self-absorbed low-energy tail with FE~E2 can produce the prompt optical emission (as in the case of GRB 990123). The first Compton scattering radiation by nearly monoenergetic electrons can then be as hard as FE~E1, reproducing the hardness of most of the observed GRB spectra. The second Compton peak should be observed in the high-energy gamma-ray band, possibly being responsible for the 10-100 MeV emission detected in GRB 941017. A significant electron-positron pair production reduces the available energy per particle, moving the spectral peaks to lower energies as the burst progresses. The regime is very robust, operates in a broad range of parameter space and can explain most of the observed GRB spectra and their temporal evolution.

  12. Constraints on the hadronic content of gamma ray bursts

    SciTech Connect

    Yacobi, Lee; Guetta, Dafne; Behar, Ehud

    2014-09-20

    The IceCube High-energy Neutrino Telescope has been collecting data since 2006. Conversely, hundreds of gamma-ray bursts (GRBs) have been detected by the GRB Monitor on board Fermi since its launch in 2008. So far no neutrino event has been associated with a GRB, despite many models predicting the generation of high-energy neutrinos through GRB photon interaction with PeV protons in the GRB jet. We use the non-detection of neutrinos to constrain the hadronic content of GRB jets independent of jet model parameters. Assuming a generic particle spectrum of E {sup –α} with α = 2, we find that the ratio of the energy carried by pions to that in electrons has to be small f {sub π}/f{sub e} ≲ 0.24 at 95% confidence level. A distribution of spectral slopes can lower f {sub π}/f{sub e} by orders of magnitude. Another limit, independent of neutrinos, is obtained if one ascribes the measured Fermi/Large Area Telescope GeV gamma-ray emission to pair-photon cascades of high-energy photons resulting from (the same photon-hadronic interactions and subsequent) neutral pion decays. Based on the generally observed MeV-to-GeV GRB fluence ratio of ≈10, we show that f {sub π}/f{sub e} ≲ 0.3. In some bursts, this ratio is as low as unity, f {sub π}/f{sub e} ≲ 0.03. These findings add to mounting doubts regarding the presence of PeV protons in GRB jets.

  13. A Tokamak Model for Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Li, L.-X.

    2001-12-01

    Two most important problems for gamma-ray bursts (GRBs) are how to generate an enormous amount of energy up to 1054 ergs, and how to make the energy clean enough (i.e. with less load of baryons) for providing a huge bulk Lorentz factor > 300. Here we present a tokamak model for GRBs. A toroidal electric current flows on the surface of a dense plasma torus spinning around a Kerr black hole, which generates a poloidal magnetic field outside the torus. On the surface of the torus the magnetic field is parallel to the surface. The closed magnetic field lines winding around the torus compress and confine the plasma in the torus, as in the case of tokamaks in controlled nuclear fusion. If the magnetic field is strong enough (typically 1015 Gauss or higher), the baryonic contamination from the plasma in the torus is greatly suppressed and a clean magnetosphere of electron-positron pairs is built up around the black hole. If some magnetic field lines threading the black hole are open and connect with plasma loads, clean energy can be extracted from the Kerr black hole by the Blandford-Znajek mechanism. The energy extracted from the black hole is converted to the kinetic energy of the electron-positron pairs in the magnetosphere around the black hole, which generates two oppositely directed jets of electron-positron pairs with super-high bulk Lorentz factors. The jets collide and interact with the interstellar medium, which produces gamma-ray bursts and the afterglows.

  14. Propagation of neutrinos through magnetized gamma-ray burst fireball

    SciTech Connect

    Sahu, Sarira; Fraija, Nissim; Keum, Yong-Yeon E-mail: nissim.ilich@nucleares.unam.mx

    2009-11-01

    The neutrino self-energy is calculated in a weakly magnetized plasma consists of electrons, protons, neutrons and their anti-particles and using this we have calculated the neutrino effective potential up to order M{sub W}{sup −4}. In the absence of magnetic field it reduces to the known result. We have also calculated explicitly the effective potentials for different backgrounds which may be helpful in different environments. By considering the mixing of three active neutrinos in the medium with the magnetic field we have derived the survival and conversion probabilities of neutrinos from one flavor to another and also the resonance condition is derived. As an application of the above, we considered the dense and relativistic plasma of the Gamma-Ray Bursts fireball through which neutrinos of 5–30 MeV can propagate and depending on the fireball parameters they may oscillate resonantly or non-resonantly from one flavor to another. These MeV neutrinos are produced due to stellar collapse or merger events which trigger the Gamma-Ray Burst. The fireball itself also produces MeV neutrinos due to electron positron annihilation, inverse beta decay and nucleonic bremsstrahlung. Using the three neutrino mixing and considering the best fit values of the neutrino parameters, we found that electron neutrinos are hard to oscillate to another flavors. On the other hand, the muon neutrinos and the tau neutrinos oscillate with equal probability to one another, which depends on the neutrino energy, temperature and size of the fireball. Comparison of oscillation probabilities with and without magnetic field shows that, they depend on the neutrino energy and also on the size of the fireball. By using the resonance condition, we have also estimated the resonance length of the propagating neutrinos as well as the baryon content of the fireball.

  15. A Study of the Gamma-Ray Burst Fundamental Plane

    NASA Astrophysics Data System (ADS)

    Dainotti, Maria; Hernandez, Xavier; Postnikov, Sergey; Nagataki, Shigehiro; O'Brien, P. T.; Willingale, Richard; Striegel, Stephanie

    2017-08-01

    Long gamma-ray bursts (GRBs) with a plateau phase in their X-ray afterglows obeys a three-dimensional (3D) relation (Dainotti et al. 2016), between the rest-frame time at the end of the plateau, Ta, its corresponding X-ray luminosity, La, and the peak luminosity in the prompt emission, Lpeak, an extension of the two-dimensional Dainotti relation. This 3D relation identifies a GRB fundamental plane whose existence we here confirm. We extend the original analysis with X-ray data untill July 2016 gathering 183 Swift GRBs with afterglow plateaus and known redshifts. We compare several GRB categories, such as shorts with extended emission, SEE, X-ray Flashes, GRBs associated with SNe, a sample of only long-duration GRBs (132), selected from the total sample by excluding GRBs of the previous categories, and the gold sample, composed by GRBs with light curves with good data coverage and relatively flat plateaus. The relation planes for each of these categories are not statistically different from the gold fundamental plane, with the exception of the SEE, which are hence identified as a physically distinct class of objects. The gold fundamental plane has an intrinsic scatter smaller than any plane derived from the other sample categories. Thus, the distance of any particular GRB category from this plane becomes a key parameter. Additionally, we tested this 3D relations by using GRBs observed at high energy, namely the peak luminosity values derived by the Fermi-Gamma Ray Burst Monitor (GBM). The 3D relation is also confirmed for GRBs observed by the GBM, thus showing its independence from the energy range. Furthermore, we computed the several category planes with T*a as a dependent parameter obtaining for each category smaller intrinsic scatters (reaching a reduction of $24\\%$ for the long GRBs). The fundamental plane is independent from several prompt and afterglow parameters.

  16. Evidence for Temporally-Extended, High-Energy Emission from Gamma Ray Burst 990104

    NASA Technical Reports Server (NTRS)

    Wren, D. N.; Bertsch, D. L.; Ritz, S.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    It is well known that high-energy emission (MeV - GeV) has been observed in several gamma ray bursts and temporally-extended emission from lower-energy gamma rays through radio wavelengths is well established. Observations of extended, high-energy emission are, however, scarce. Here we present evidence for a gamma ray burst emission that is both high-energy and extended, coincident with lower energy emissions. For the very bright and long burst, GRB 990104, we show light curves and spectra that confirm emission above 50 MeV, approximately 152 seconds after the BATSE (Burst and Transient Source Experiment) trigger and initial burst emission. Between the initial output and the main peak, seen at both low and high energy, there was a period of approx. 100 s during which the burst was relatively quiet. This burst was found as part of an ongoing search for high-energy emission in gamma ray bursts.

  17. Short and long gamma-ray bursts: same emission mechanism?

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Ghisellini, G.; Nava, L.

    2011-11-01

    We study the spectral evolution on second and subsecond time-scales in 11 long and 12 short gamma-ray bursts (GRBs) with peak flux >8.5 × 10-6 erg cm-2 s (8 keV-35 MeV) detected by the Fermi satellite. The peak flux correlates with the time-averaged peak energy in both classes of bursts. The peak energy evolution, as a function of time, tracks the evolution of the flux on short time-scales in both short and long GRBs. We do not find evidence of a hard-to-soft spectral evolution. While short GRBs have observed peak energies larger than few MeV during most of their evolution, long GRBs can start with a softer peak energy (of few hundreds keV) and become as hard as short ones (i.e. with Eobspeak larger than few MeV) at the peak of their light curve. Six GRBs in our sample have a measured redshift. In these few cases we find that their correlations between the rest frame Epeak and the luminosity Liso are less scattered than their correlations in the observer frame between the peak energy Eobspeak and the flux P. We find that the rest frame Epeak of long bursts can be as high or even larger than that of short GRBs and that short and long GRBs follow the same Epeak(t)-Liso(t) correlation, despite the fact that they likely have different progenitors.

  18. Yet Another Model of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Katz, J. I.

    1997-12-01

    Sari & Piran have demonstrated that the time structure of gamma-ray bursts (GRBs) must reflect the time structure of their energy release. A model that satisfies this condition uses the electrodynamic emission of energy by the magnetized rotating ring of dense matter left by neutron star coalescence; GRBs are essentially fast, high-field, differentially rotating pulsars. The energy densities are large enough for the power to appear as an outflowing equilibrium pair plasma, which produces the burst by baryon entrainment and subsequent internal shocks. In this paper the magnetic field and the characteristic timescale for its rearrangement--which determines the observed time structure of the burst--are estimated. There may be quasi-periodic oscillations at the rotational frequencies, which are predicted to range up to 5770 Hz (in a local frame). This model is one of a general class of electrodynamic accretion models that includes the Blandford and Lovelace model of active galactic nuclei and that can also be applied to black hole X-ray sources of stellar mass. The apparent efficiency of nonthermal particle acceleration is predicted to be 10%-50%, but higher values are possible if the underlying accretion flow is super-Eddington.

  19. Possible Evidence for Relativistic Shocks in Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Cohen, E.; Katz, J. I.; Piran, T.; Sari, R.; Preece, R. D.; Band, D. L.

    1997-01-01

    Relativistic shock models of gamma-ray bursts may be tested by comparing their predicted low-energy asymptotic spectral indices s to observations. Synchrotron radiation theory predicts that the instantaneous spectrum has s = 1/3, and the spectrum integrated over the radiative decay of the electrons' energies has s = 1/2 with other cases lying between these limits. We examine the spectra of 11 bursts obtained by the Large Area Detectors on BATSE. One agrees with the predicted instantaneous spectrum, as does the initial portion of a second, and three are close to the predicted integrated spectrum. All of the observed asymptotic spectral slopes lie in the predicted range. This evidence for relativistic shocks is independent of detailed models of bursts and of assumptions about their distances. Radiation observed with the predicted instantaneous spectrum has a comparatively smooth time dependence, consistent with the necessarily long radiation time, while radiation observed with the predicted integrated spectrum has a spiky time dependence, consistent with the necessarily short radiation time.

  20. The first gamma-ray bursts in the universe

    SciTech Connect

    Mesler, R. A.; Pihlström, Y. M.; Whalen, Daniel J.; Smidt, Joseph; Fryer, Chris L.; Lloyd-Ronning, N. M.

    2014-05-20

    Gamma-ray bursts (GRBs) are the ultimate cosmic lighthouses, capable of illuminating the universe at its earliest epochs. Could such events probe the properties of the first stars at z ∼ 20, the end of the cosmic Dark Ages? Previous studies of Population III (Pop III) GRBs only considered explosions in the diffuse relic H II regions of their progenitors or bursts that are far more energetic than those observed to date. However, the processes that produce GRBs at the highest redshifts likely reset their local environments, creating much more complicated structures than those in which relativistic jets have been modeled so far. These structures can greatly affect the luminosity of the afterglow and hence the redshift at which it can be detected. We have now simulated Pop III GRB afterglows in H II regions, winds, and dense shells ejected by the star during the processes that produce the burst. We find that GRBs with E {sub iso,γ} = 10{sup 51}-10{sup 53} erg will be visible at z ≳ 20 to the next generation of near infrared and radio observatories. In many cases, the environment of the burst, and hence progenitor type, can be inferred from the afterglow light curve. Although some Pop III GRBs are visible to Swift and the Very Large Array now, the optimal strategy for their detection will be future missions like the proposed EXIST and JANUS missions with large survey areas and onboard X-ray and infrared telescopes that can track their near-infrared flux from the moment of the burst, thereby identifying their redshifts.

  1. The First Gamma-Ray Bursts in the Universe

    NASA Astrophysics Data System (ADS)

    Mesler, R. A.; Whalen, Daniel J.; Smidt, Joseph; Fryer, Chris L.; Lloyd-Ronning, N. M.; Pihlström, Y. M.

    2014-05-01

    Gamma-ray bursts (GRBs) are the ultimate cosmic lighthouses, capable of illuminating the universe at its earliest epochs. Could such events probe the properties of the first stars at z ~ 20, the end of the cosmic Dark Ages? Previous studies of Population III (Pop III) GRBs only considered explosions in the diffuse relic H II regions of their progenitors or bursts that are far more energetic than those observed to date. However, the processes that produce GRBs at the highest redshifts likely reset their local environments, creating much more complicated structures than those in which relativistic jets have been modeled so far. These structures can greatly affect the luminosity of the afterglow and hence the redshift at which it can be detected. We have now simulated Pop III GRB afterglows in H II regions, winds, and dense shells ejected by the star during the processes that produce the burst. We find that GRBs with E iso, γ = 1051-1053 erg will be visible at z >~ 20 to the next generation of near infrared and radio observatories. In many cases, the environment of the burst, and hence progenitor type, can be inferred from the afterglow light curve. Although some Pop III GRBs are visible to Swift and the Very Large Array now, the optimal strategy for their detection will be future missions like the proposed EXIST and JANUS missions with large survey areas and onboard X-ray and infrared telescopes that can track their near-infrared flux from the moment of the burst, thereby identifying their redshifts.

  2. The x-/gamma-ray camera ECLAIRs for the gamma-ray burst mission SVOM

    NASA Astrophysics Data System (ADS)

    Godet, O.; Nasser, G.; Atteia, J.-.; Cordier, B.; Mandrou, P.; Barret, D.; Triou, H.; Pons, R.; Amoros, C.; Bordon, S.; Gevin, O.; Gonzalez, F.; Götz, D.; Gros, A.; Houret, B.; Lachaud, C.; Lacombe, K.; Marty, W.; Mercier, K.; Rambaud, D.; Ramon, P.; Rouaix, G.; Schanne, S.; Waegebaert, V.

    2014-07-01

    We present ECLAIRs, the Gamma-ray burst (GRB) trigger camera to fly on-board the Chinese-French mission SVOM. ECLAIRs is a wide-field (~ 2 sr) coded mask camera with a mask transparency of 40% and a 1024 cm2 detection plane coupled to a data processing unit, so-called UGTS, which is in charge of locating GRBs in near real time thanks to image and rate triggers. We present the instrument science requirements and how the design of ECLAIRs has been optimized to increase its sensitivity to high-redshift GRBs and low-luminosity GRBs in the local Universe, by having a low-energy threshold of 4 keV. The total spectral coverage ranges from 4 to 150 keV. ECLAIRs is expected to detect ~ 200 GRBs of all types during the nominal 3 year mission lifetime. To reach a 4 keV low-energy threshold, the ECLAIRs detection plane is paved with 6400 4 × 4 mm2 and 1 mm-thick Schottky CdTe detectors. The detectors are grouped by 32, in 8×4 matrices read by a low-noise ASIC, forming elementary modules called XRDPIX. In this paper, we also present our current efforts to investigate the performance of these modules with their front-end electronics when illuminated by charged particles and/or photons using radioactive sources. All measurements are made in different instrument configurations in vacuum and with a nominal in-flight detector temperature of -20°C. This work will enable us to choose the in-flight configuration that will make the best compromise between the science performance and the in-flight operability of ECLAIRs. We will show some highlights of this work.

  3. The Spectral Evolution of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Band, David L.

    1999-01-01

    The proposed project was a continuation of our work on the spectral evolution of gamma-ray bursts begun when the Co-I on this proposal. Lyle Ford, was my graduate student. In the proposal we discussed two projects. The first was finishing and publishing the last chapter of Professor Ford's thesis. In this research effort we looked for correlations in the energies of pairs of counts recorded by the BATSE Spectroscopy Detectors within a short time of each other. A greater correlation within a short time would indicate that the observed broadband spectrum is really composed of narrowband spectral components which last for a short time and which rapidly sum to the observed spectrum. We did not find any evidence for such narrowband emission, and are setting limits on its presence. Professor Ford is revising the last chapter of his thesis for publication with my participation. The second project was a continuation of my study of the cross-correlations between the gamma-ray burst lightcurves in different energy bands. I published a first study with this technique (1997. Ap.J., 486, 928) which showed that "hard-to-soft" spectral evolution is prevalent both within and between the bursts' intensity spikes. I proposed to continue developing this technique. However, I have been somewhat disillusioned about using this methodology quantitatively since it averages the spectral evolution on a given timescale over the entire burst. Nonetheless, I have been applying the technique to new bursts which are scientifically interesting for other reasons. Attached I include the cross-correlations for the burst GRB 990123, the burst during which ROTSE discovered an optical transient. The solid curve is the autocorrelatl'on of BATSE's channel 3 (100-300 keV), while the dashed, dot-dashed and 3 dots-dashed curves are the crosscorrelations of channel 3 with channels 1 (25-50 keV), 2 (50-100 keV), and 4 (300-2000 keV). The order of, and separation between, the curves on the positive lag side

  4. Strong gamma-ray bursts observed by COMPTEL during its second year of operation

    NASA Technical Reports Server (NTRS)

    Kippen, R. M.; Connors, A.; Mcconnell, M.; Ryan, J.; Collmar, W.; Greiner, J.; Schonfelder, V.; Varendorff, M.; Hermsen, W.; Kuiper, L.

    1995-01-01

    The imaging Compton telescope (COMPTEL) onboard the Compton Gamma Ray Observatory (CGRO) can localize gamma-ray bursts occurring inside its approximately 1 sr field-of-view in the energy range from 0.75 to 30 MeV with location accuracy of 1 deg. Additional time-resolved spectral measurements in the energy range 0.1 to 10 MeV are made by individual COMPTEL 'burst' detectors. During its second year of operation COMPTEL observed several gamma-ray bursts. Locations of five strong bursts (including the rapidly imaged events GRB 930131 and GRB 930309) are presented here along with the findings from preliminary spectral analysis.

  5. Modeling Gamma Ray Bursts in the Megnetically Dominated Regime

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    Recent observations of broad-band prompt emission spectra of gamma-ray bursts (GRBs) by the Fermi Gamma-Ray Telescope suggest that they do not comply with the predictions of the standard fireball internal shock model. Several independent observations (including detections of high polarization degree of gamma-ray emission and early optical emission of some GRBs, as well as non-detection of PeV neutrinos from GRBs by IceCube) support or are consistent with the hypothesis that at least some GRBs have magnetically dominated jets. This calls for serious, detailed investigations of GRB models in the magnetically dominated regime, which interpret GRB emission as dissipation of strong magnetic fields entrained in the ejecta. On the other hand, because of their complexity, magnetic models are so far much less developed than the baryonic fireball models. Here we propose to tackle this difficult problem, aiming at making solid progress in this direction through a set of numerical investigations. Specifically, we propose to carry out the following simulations. (1) Using a relativistic MHD code, we will perform a global simulation to investigate whether efficient magnetic dissipation would occur when two high-σ magnetic blobs collide with a relativistic speed. (2) We will perform a local simulation of the relativistic collisions between two high-σ fluids, and track the evolution of magnetic field configuration in the colliding region and the interplay between magnetic reconnection and development of magnetic turbulence. (3) Through injecting test particles in the simulation box, we will study how electrons get accelerated in the turbulent reconnection regions. (4) Built upon the above-mentioned numerical simulation results, along with a Monte Carlo code and a synchrotron radiation code developed in our group before, we will develop a full numerical model to simulate lightcurves, time-dependent spectra, and polarization properties of GRB prompt emission within the framework of

  6. 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.

  7. A NEW CLASSIFICATION METHOD FOR GAMMA-RAY BURSTS

    SciTech Connect

    Lue Houjun; Liang Enwei; Zhang Binbin; Zhang Bing E-mail: zhang@physics.unlv.ed

    2010-12-20

    Recent Swift observations suggest that the traditional long versus short gamma-ray burst (GRB) classification scheme does not always associate GRBs to the two physically motivated model types, i.e., Type II (massive star origin) versus Type I (compact star origin). We propose a new phenomenological classification method of GRBs by introducing a new parameter {epsilon} = E{sub {gamma},iso,52}/E {sup 5/3}{sub p,z,2}, where E{sub {gamma},iso} is the isotropic gamma-ray energy (in units of 10{sup 52} erg) and E{sub p,z} is the cosmic rest-frame spectral peak energy (in units of 100 keV). For those short GRBs with 'extended emission', both quantities are defined for the short/hard spike only. With the current complete sample of GRBs with redshift and E{sub p} measurements, the {epsilon} parameter shows a clear bimodal distribution with a separation at {epsilon} {approx} 0.03. The high-{epsilon} region encloses the typical long GRBs with high luminosity, some high-z 'rest-frame-short' GRBs (such as GRB 090423 and GRB 080913), as well as some high-z short GRBs (such as GRB 090426). All these GRBs have been claimed to be of Type II origin based on other observational properties in the literature. All the GRBs that are argued to be of Type I origin are found to be clustered in the low-{epsilon} region. They can be separated from some nearby low-luminosity long GRBs (in 3{sigma}) by an additional T{sub 90} criterion, i.e., T{sub 90,z} {approx}< 5 s in the Swift/BAT band. We suggest that this new classification scheme can better match the physically motivated Type II/I classification scheme.

  8. A New Classification Method for Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Lü, Hou-Jun; Liang, En-Wei; Zhang, Bin-Bin; Zhang, Bing

    2010-12-01

    Recent Swift observations suggest that the traditional long versus short gamma-ray burst (GRB) classification scheme does not always associate GRBs to the two physically motivated model types, i.e., Type II (massive star origin) versus Type I (compact star origin). We propose a new phenomenological classification method of GRBs by introducing a new parameter ɛ = E γ,iso,52/E 5/3 p,z,2, where E γ,iso is the isotropic gamma-ray energy (in units of 1052 erg) and E p,z is the cosmic rest-frame spectral peak energy (in units of 100 keV). For those short GRBs with "extended emission," both quantities are defined for the short/hard spike only. With the current complete sample of GRBs with redshift and Ep measurements, the ɛ parameter shows a clear bimodal distribution with a separation at ɛ ~ 0.03. The high-ɛ region encloses the typical long GRBs with high luminosity, some high-z "rest-frame-short" GRBs (such as GRB 090423 and GRB 080913), as well as some high-z short GRBs (such as GRB 090426). All these GRBs have been claimed to be of Type II origin based on other observational properties in the literature. All the GRBs that are argued to be of Type I origin are found to be clustered in the low-ɛ region. They can be separated from some nearby low-luminosity long GRBs (in 3σ) by an additional T 90 criterion, i.e., T 90,z <~ 5 s in the Swift/BAT band. We suggest that this new classification scheme can better match the physically motivated Type II/I classification scheme.

  9. SVOM: a new mission for Gamma-Ray Burst Studies

    NASA Astrophysics Data System (ADS)

    Götz, D.; Paul, J.; Basa, S.; Wei, J.; Zhang, S. N.; Atteia, J.-L.; Barret, D.; Cordier, B.; Claret, A.; Deng, J.; Fan, X.; Hu, J. Y.; Huang, M.; Mandrou, P.; Mereghetti, S.; Qiu, Y.; Wu, B.

    2009-05-01

    We present the SVOM (Space-based multi-band astronomical Variable Object Monitor) mission, that is being developed in cooperation between the Chinese National Space Agency (CNSA), the Chinese Academy of Science (CAS) and the French Space Agency (CNES), and is expected to be launched in 2013. Its scientific objectives include the study of the GRB phenomenon (diversity and unity), GRB physics (particle acceleration, radiation mechanisms), GRB progenitors, cosmology (host galaxies, intervening medium, star formation history, re-ionization, cosmological parameters), and fundamental physics (origin of cosmic rays, Lorentz invariance, gravitational waves sources). SVOM is designed to detect all known types of Gamma-Ray Bursts (GRBs), to provide fast and reliable GRB positions, to measure the broadband spectral characteristics and temporal properties of the GRB prompt emission. This will be obtained in first place thanks to a set of four space flown instruments. A wide field (~2 sr) coded mask telescope (ECLAIRs), operating in the 4-250 keV energy range, will provide the triggers and localizations, while a gamma-ray non-imaging spectrometer (GRM), sensitive in the 50 keV-5 MeV domain, will extend the prompt emission energy coverage. After a satellite slew, in order to place the GRB direction within field of view of the two narrow field instruments-a soft X-ray (XIAO), and a visible telescope (VT)-the GRB position will be refined and the study of the early phases of the GRB afterglow will be possible. A set of three ground based dedicated instruments, two robotic telescopes (GFTs) and a wide angle optical monitor (GWAC), will complement the space borne instruments. Thanks to the low energy trigger threshold (~4 keV) of the ECLAIRs, SVOM is ideally suited for the detection of soft, hence potentially most distant, GRBs. Its observing strategy is optimized to facilitate follow-up observations from the largest ground based facilities.

  10. STATISTICAL PROPERTIES OF GAMMA-RAY BURST POLARIZATION

    SciTech Connect

    Toma, Kenji; Sakamoto, Takanori; Hill, Joanne E.; Zhang, Bing; McConnell, Mark L.; Bloser, Peter F.; Yamazaki, Ryo; Ioka, Kunihito; Nakamura, Takashi

    2009-06-20

    The emission mechanism and the origin and structure of magnetic fields in gamma-ray burst (GRB) jets are among the most important open questions concerning the nature of the central engine of GRBs. In spite of extensive observational efforts, these questions remain to be answered and are difficult or even impossible to infer with the spectral and light-curve information currently collected. Polarization measurements will lead to unambiguous answers to several of these questions. Recent developments in X-ray and {gamma}-ray polarimetry techniques have demonstrated a significant increase in sensitivity, enabling several new mission concepts, e.g., Polarimeters for Energetic Transients (POET), providing wide field of view and broadband polarimetry measurements. If launched, missions of this kind would finally provide definitive measurements of GRB polarizations. We perform Monte Carlo simulations to derive the distribution of GRB polarizations in three emission models; the synchrotron model with a globally ordered magnetic field (SO model), the synchrotron model with a small-scale random magnetic field (SR model), and the Compton drag model (CD model). The results show that POET, or other polarimeters with similar capabilities, can constrain the GRB emission models by using the statistical properties of GRB polarizations. In particular, the ratio of the number of GRBs for which the polarization degrees can be measured to the number of GRBs that are detected (N{sub m} /N{sub d} ) and the distributions of the polarization degrees ({pi}) can be used as the criteria. If N{sub m} /N{sub d} > 30% and {pi} is clustered between 0.2 and 0.7, the SO model will be favored. If, instead, N{sub m} /N{sub d} < 15%, then the SR or CD model will be favored. If several events with {pi}>0.8 are observed, then the CD model will be favored.

  11. A revised analysis of gamma-ray bursts' prompt efficiencies

    NASA Astrophysics Data System (ADS)

    Beniamini, Paz; Nava, Lara; Piran, Tsvi

    2016-09-01

    The prompt gamma-ray bursts' (GRBs) efficiency is an important clue on the emission mechanism producing the γ-rays. Previous estimates of the kinetic energy of the blast waves, based on the X-ray afterglow luminosity LX, suggested that this efficiency is large, with values above 90 per cent in some cases. This poses a problem to emission mechanisms and in particular to the internal shocks model. These estimates are based, however, on the assumption that the X-ray emitting electrons are fast cooling and that their Inverse Compton (IC) losses are negligible. The observed correlations between LX (and hence the blast wave energy) and Eγ, iso, the isotropic equivalent energy in the prompt emission, has been considered as observational evidence supporting this analysis. It is reasonable that the prompt gamma-ray energy and the blast wave kinetic energy are correlated and the observed correlation corroborates, therefore, the notion LX is indeed a valid proxy for the latter. Recent findings suggest that the magnetic field in the afterglow shocks is significantly weaker than was earlier thought and its equipartition fraction, ɛB, could be as low as 10-4 or even lower. Motivated by these findings we reconsider the problem, taking now IC cooling into account. We find that the observed LX - Eγ, iso correlation is recovered also when IC losses are significant. For small ɛB values the blast wave must be more energetic and we find that the corresponding prompt efficiency is significantly smaller than previously thought. For example, for ɛB ˜ 10-4 we infer a typical prompt efficiency of ˜15 per cent.

  12. The SKA View of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Burlon, D.; Ghirlanda, G.; van der Horst, A.; Murphy, T.; Wijers, R. A. M. J.; Gaensler, B.; Ghisellini, G.; Prandoni, I.

    2015-04-01

    Gamma-ray bursts (GRBs) are some of the most extreme events in the Universe. As well as providing a natural laboratory for investigating fundamental physical processes, they might trace the cosmic star formation rate up to extreme redshifts and probe the composition of the intergalactic medium over most of the Universe's history. Radio observations of GRBs play a key part in determining their physical properties, but currently they are largely limited to follow-up observations of $\\gamma$-ray-detected objects. The SKA will significantly increase our ability to study GRB afterglows, following up several hundred objects in the high frequency bands already in the "early science" implementation of the telescope. SKA1-MID Bands 4 (4 GHz) and 5 (9.2 GHz) will be particularly suited to the detection of these transient phenomena. The SKA will trace the peak of the emission, sampling the thick-to-thin transition of the evolving spectrum, and follow-up the afterglow down to the time the ejecta slow down to non-relativistic speeds. The full SKA will be able to observe the afterglows across the non-relativistic transition, for ~25% of the whole GRB population. This will allow us to get a significant insight into the true energy budget of GRBs, probe their surrounding density profile, and the shock microphysics. The SKA will also be able to routinely detect the elusive "orphan afterglow" emission, from the population of GRBs whose jets are not pointed towards the Earth. We expect that a deep all-sky survey such as SKA1-SUR will see around 300 orphan afterglows every week. We predict these detection to be >1000 when the full SKA telescope will be operational.

  13. Testing an unifying view of Gamma Ray Burst afterglows

    NASA Astrophysics Data System (ADS)

    Nardini, M.; Ghisellini, G.; Ghirlanda, G.; Celotti, A.

    2011-04-01

    Four years after the launch the Swift satellite the nature of the Gamma Ray Bursts (GRBs) broadband afterglow behaviour is still an open issue. The standard external shock fireball model cannot easily explain the combined temporal and spectral properties of optical to X-ray afterglows. We analysed the rest frame de-absorbed and K-corrected optical and X-ray light curves of a sample of 33 GRBs with known redshift and optical extinction at the host frame. We modelled their broadband behaviour as the sum of the standard forward shock emission due to the interaction of a fireball with the circum-burst medium and an additional component. This description provides a good agreement with the observed light curves despite their complexity and diversity and can also account for the lack of achromatic late times jet breaks and the presence of chromatic breaks in several GRBs lightcurves. In order to test the predictions of such modelling we analysed the X-ray time resolved spectra searching for possible spectral breaks within the observed XRT energy band, finding seven GRBs showing such a break. The optical to X-ray SED evolution of these GRBs are consistent with what expected by our interpretation.

  14. The rate and luminosity function of long gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Pescalli, A.; Ghirlanda, G.; Salvaterra, R.; Ghisellini, G.; Vergani, S. D.; Nappo, F.; Salafia, O. S.; Melandri, A.; Covino, S.; Götz, D.

    2016-03-01

    We derive, adopting a direct method, the luminosity function and the formation rate of long Gamma Ray Bursts through a complete, flux-limited, sample of Swift bursts which has a high level of completeness in redshift z (~82%). We parametrise the redshift evolution of the GRB luminosity as L = L0(1 + z)k and we derive k = 2.5, consistently with recent estimates. The de-evolved luminosity function φ(L0) of GRBs can be represented by a broken power law with slopes a = -1.32 ± 0.21 and b = -1.84 ± 0.24 below and above, respectively, a break luminosity L0,b = 1051.45±0.15 erg/s. Under the hypothesis of luminosity evolution we find that the GRB formation rate increases with redshift up to z ~ 2, where it peaks, and then decreases in agreement with the shape of the cosmic star formation rate. We test the direct method through numerical simulations and we show that if it is applied to incomplete (both in redshift and/or flux) GRB samples it can misleadingly result in an excess of the GRB formation rate at low redshifts.

  15. Observations of Gamma-Ray Bursts by HETE-2

    NASA Technical Reports Server (NTRS)

    Kawai, N.; Matsuoka, M.; Yoshida, A.; Shirasaki, Y.; Ricker, G.; Doty, J.; Vanderspek, R.; Crew, G.; Villasenor, J.; Atteia, J.-L.; Fenimore, E. E.; Galassi, M.; Lamb, D. Q.; Graziani, C.; Hurley, K.; Jernigan, J. G.; Woosley, S.; Martel, F.; Monnelly, G.; Prigozhin, G.; Olive, J.-F.; Dezalay, J.P.; Boer, M.; Pizzichini, G.; Cline, T.

    2004-01-01

    The High Energy Transient Explorer 2 (HETE-2), launched in October 2000, is currently localizing gamma-ray bursts (GRBs) at a rate of approximately 20/yr, many in real time. As of August 2003, HETE-2 had localized 43 GRBs; 16 localizations had led to the detection of an X-ray, optical, or radio afterglows. The prompt position notification of HETE-2 enabled probing the nature of so-called "dark bursts" for which no optical afterglows were found despite of accurate localizations. In some cases, the optical afterglow was found to be intrinsically faint , and its flux declined rapidly. In another case, the optical emission was likely to be extinguished by the dust in the vicinity of the GRB source. The bright afterglows of GRB021004 and GRB030329 were observed in unprecedented details by telescopes around the world. Strong evidence for the association of long GRBs with the core-collapse supernovae was found. HETE-2 has localized almost as many X-ray rich GRBs as classical GRBs. The nature of the X-ray rich GRBs and X-ray flashes have been studied systematically with HETE-2, and they are found to have many properties in common with the classical GRBs, suggesting that they are a single phenomenon.

  16. Ideal engine durations for gamma-ray-burst-jet launch

    NASA Astrophysics Data System (ADS)

    Hamidani, Hamid; Takahashi, Koh; Umeda, Hideyuki; Okita, Shinpei

    2017-08-01

    Aiming to study gamma-ray-burst (GRB) engine duration, we present numerical simulations to investigate collapsar jets. We consider typical explosion energy (1052 erg) but different engine durations, in the widest domain to date from 0.1 to 100 s. We employ an adaptive mesh refinement 2D hydrodynamical code. Our results show that engine duration strongly influences jet nature. We show that the efficiency of launching and collimating relativistic outflow increases with engine duration, until the intermediate engine range where it is the highest, past this point to long engine range, the trend is slightly reversed; we call this point where acceleration and collimation are the highest 'sweet spot' (∼10-30 s). Moreover, jet energy flux shows that variability is also high in this duration domain. We argue that not all engine durations can produce the collimated, relativistic and variable long GRB jets. Considering a typical progenitor and engine energy, we conclude that the ideal engine duration to reproduce a long GRB is ∼10-30 s, where the launch of relativistic, collimated and variable jets is favoured. We note that this duration domain makes a good link with a previous study suggesting that the bulk of Burst and Transient Source Experiment's long GRBs is powered by ∼10-20 s collapsar engines.

  17. A MAD model for gamma-ray burst variability

    NASA Astrophysics Data System (ADS)

    Lloyd-Ronning, Nicole M.; Dolence, Joshua C.; Fryer, Christopher L.

    2016-09-01

    We present a model for the temporal variability of long gamma-ray bursts (GRBs) during the prompt phase (the highly variable first 100 s or so), in the context of a magnetically arrested disc (MAD) around a black hole. In this state, sufficient magnetic flux is held on to the black hole such that it stalls the accretion near the inner region of the disc. The system transitions in and out of the MAD state, which we relate to the variable luminosity of the GRB during the prompt phase, with a characteristic time-scale defined by the free-fall time in the region over which the accretion is arrested. We present simple analytic estimates of the relevant energetics and time-scales, and compare them to GRB observations. In particular, we show how this model can reproduce the characteristic one second time-scale that emerges from various analyses of the prompt emission light curve. We also discuss how our model can accommodate the potentially physically important correlation between a burst quiescent time and the duration of its subsequent pulse.

  18. Gamma-ray bursts and the fireball model

    NASA Astrophysics Data System (ADS)

    Piran, T.

    1999-06-01

    Gamma-ray bursts (GRBs) have puzzled astronomers since their accidental discovery in the late 1960s. The BATSE detector on the COMPTON-GRO satellite has been detecting one burst per day for the last six years. Its findings have revolutionized our ideas about the nature of these objects. They have shown that GRBs are at cosmological distances. This idea was accepted with difficulties at first. The recent discovery of an X-ray afterglow by the Italian/Dutch satellite BeppoSAX has led to a detection of high red-shift absorption lines in the optical afterglow of GRB970508 and in several other bursts and to the identification of host galaxies to others. This has confirmed the cosmological origin. Cosmological GRBs release ~1051-1053erg in a few seconds making them the most (electromagnetically) luminous objects in the Universe. The simplest, most conventional, and practically inevitable, interpretation of these observations is that GRBs result from the conversion of the kinetic energy of ultra-relativistic particles or possibly the electromagnetic energy of a Poynting flux to radiation in an optically thin region. This generic ``fireball'' model has also been confirmed by the afterglow observations. The ``inner engine'' that accelerates the relativistic flow is hidden from direct observations. Consequently, it is difficult to infer its structure directly from current observations. Recent studies show, however, that this ``inner engine'' is responsible for the complicated temporal structure observed in GRBs. This temporal structure and energy considerations indicates that the ``inner engine'' is associated with the formation of a compact object - most likely a black hole.

  19. Are short Gamma Ray Bursts similar to long ones?

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Bernardini, M. G.; Calderone, G.; D'Avanzo, P.

    2015-09-01

    The apparent separation of short and long Gamma-Ray Bursts (GRBs) in the hardness ratio vs duration plot has been considered as a direct evidence of the difference between these two populations. The origin of this diversity, however, has been only confirmed with larger GRB samples but not fully understood. In particular, the hardness ratio is only a proxy of the shape of the spectra of GRBs and itself, together with the observed duration, does not consider the possible different redshift distribution of short and long bursts, which might arise from their different progenitors' nature. By correcting the spectral shape of short and long GRBs for the redshift effects, short GRBs are harder than long ones due to a harder low energy spectral component while the two populations have similar (rest frame) peak energy. In the rest frame, the temporal break of the long/short duration distribution is blurred away and short and long GRBs have a continuous differential duration distribution. Moreover, they show similar luminosities but their energetics differ by a factor proportional to their different average duration. The spectral evolution of long GRBs shows that the initial phase (of the order of 0.3 s rest frame) has similar spectral properties of that of short GRBs. As a consequence, the different hardness at low energies might be due to a prolonged spectral evolution of long GRBs with respect to short ones. Finally, we show that long GRBs can have a null lag similarly to short bursts. Moreover, we find that a considerable fraction of long (and most of short) GRBs are inconsistent with the lag-luminosity relation which could be a boundary in the corresponding plane, rather than a correlation.

  20. Integrated criteria of gamma-ray bursts spectral hardness

    NASA Astrophysics Data System (ADS)

    Arkhangelskaja, I. V.; Voevodina, E. V.; Zenin, A. A.

    2013-02-01

    Most part of gamma-ray bursts (GRBs) spectra are well described by Band model with following parameters: α, β (spectral indices in low and high energy bands) and Epeak (energy of spectral peak). For several GRB parameter β characterizing the spectral shape in the region up to some hundred MeV (for example, GRB100724B). Moreover, Band spectrum of GRB080916C covering 6 orders of magnitude. Until recently spectral hardness parameter H32 (the ratio of total counts in the 100 - 300 keV and 50 - 100 keV energy range) was used for additional classification events on hard and soft, for GRBs groups selection on hardness and duration distributions (subgroup of intermediate bursts) and so on. However, H32 is defined in energy intervals 50-100 keV and 100-300 keV, but for some GRB Epeak> 300 keV and this value is outside regions of H32 definition. Thus, parameter H32 is incompletely represents spectral properties of such events. Basing on Band model we introduce new integral criteria could be used in the wide energy band for data analysis in past experiments such as BATSE (0.02 - 2 MeV), COMPTEL (0.8 - 30 MeV); EGRET (20 MeV - 30 GeV); in now operated experiments Fermi (8 keV - 1MeV, 200 keV - 40 MeV and 300 MeV - 300 GeV), AGILE (18 - 60 keV and 30 MeV - 50 GeV) and in future experiments: GAMMA-400 (0.1 - 3000 GeV) and so on. In the present work spectral parameters taken from BATSE and from Fermi catalogues were analyzed and the new integral criteria were investigated. Results of data studying have shown that new criteria allow making GRB classification including intermediate bursts subgroup separation.

  1. A Non-Triggered Burst Supplement to the BATSE Gamma-Ray Burst Catalogs

    NASA Technical Reports Server (NTRS)

    Kommers, J.; Lewin, W. H.; Kouveliotou, C.; vanParadijs, J.; Pendleton, G. N.; Meegan, C. A.; Fishman, G. J.

    1998-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) with a real-time burst detection (or "trigger") system running onboard the spacecraft. Under some circumstances, however, a GRB may not activate the onboard burst trigger. For example, the burst may be too faint to exceed the onboard detection threshold, or it may occur while the onboard burst trigger is disabled for technical reasons. This paper is a catalog of such "non-triggered" GRBs that were detected in a search of the archival continuous data from BATSE. It lists 873 non-triggered bursts that were recorded between 1991 December 9.0 and 1997 December 17.0. For each burst, the catalog gives an estimated source direction, duration, peak flux, and fluence. Similar data are presented for 50 additional bursts of unknown origin that were detected in the 25-50 keV range; these events may represent the low-energy "tail" of the GRB spectral distribution. This catalog increases the number of GRBs detected with BATSE by 48% during the time period covered by the search.

  2. A Non-Triggered Burst Supplement to the BATSE Gamma-Ray Burst Catalogs

    NASA Technical Reports Server (NTRS)

    Kommers, J.; Lewin, W. H.; Kouveliotou, C.; vanParadijs, J.; Pendleton, G. N.; Meegan, C. A.; Fishman, G. J.

    1998-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) with a real-time burst detection (or "trigger") system running onboard the spacecraft. Under some circumstances, however, a GRB may not activate the onboard burst trigger. For example, the burst may be too faint to exceed the onboard detection threshold, or it may occur while the onboard burst trigger is disabled for technical reasons. This paper is a catalog of such "non-triggered" GRBs that were detected in a search of the archival continuous data from BATSE. It lists 873 non-triggered bursts that were recorded between 1991 December 9.0 and 1997 December 17.0. For each burst, the catalog gives an estimated source direction, duration, peak flux, and fluence. Similar data are presented for 50 additional bursts of unknown origin that were detected in the 25-50 keV range; these events may represent the low-energy "tail" of the GRB spectral distribution. This catalog increases the number of GRBs detected with BATSE by 48% during the time period covered by the search.

  3. Effects of Cosmic Infrared Background on High Energy Delayed Gamma-Rays From Gamma-Ray Bursts

    SciTech Connect

    Murase, Kohta; Asano, Katsuaki; Nagataki, Shigehiro; /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park

    2007-04-06

    Regenerated high energy emissions from gamma-ray bursts (GRBs) are studied in detail. If the primary emission spectrum extends to TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The created high energy electron-positron pairs up-scatter not only cosmic microwave background (CMB) photons but also CIB photons, and secondary photons are generated in the GeV-TeV range. These secondary delayed photons may be observed in the near future, and useful for a consistency check for the primary spectra and GRB physical parameters. The up-scattered CIB photons cannot be neglected for low redshift bursts and/or GRBs with a relatively low maximum photon energy. The secondary gamma-rays also give us additional information on the CIB, which is uncertain in observations so far.

  4. ON THE RECENTLY DISCOVERED CORRELATIONS BETWEEN GAMMA-RAY AND X-RAY PROPERTIES OF GAMMA-RAY BURSTS

    SciTech Connect

    Dado, Shlomo; Dar, Arnon

    2013-09-20

    Recently, many correlations between the prompt {gamma}-ray emission properties and the X-ray afterglow properties of gamma-ray bursts (GRBs) have been inferred from a comprehensive analysis of the X-ray light curves of more than 650 GRBs measured with the Swift X-Ray Telescope (Swift/XRT) during the years 2004-2010. We show that these correlations are predicted by the cannonball (CB) model of GRBs. They result from the dependence of GRB observables on the bulk motion Lorentz factor and viewing angle of the jet of highly relativistic plasmoids (CBs) that produces the observed radiations by interaction with the medium through which it propagates. Moreover, despite their different physical origins, long GRBs (LGRBs) and short-hard bursts (SHBs) in the CB model share similar kinematic correlations, which can be combined into triple correlations satisfied by both LGRBs and SHBs.

  5. A New Variability Parameter for Gamma-Ray Burst Time Profiles

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick

    1994-01-01

    We present a parameter that measures the structure of gamma-ray burst time profiles. This parameter is based on the statistics of runs and is a good measure of time profile variability. It is shown to be independent of burst duration and less sensitive to burst distance than algorithms that depend directly on the intensity of a burst.

  6. High energy neutrinos from gamma-ray bursts with precursor supernovae.

    PubMed

    Razzaque, Soebur; Mészáros, Peter; Waxman, Eli

    2003-06-20

    The high energy neutrino signature from proton-proton and photo-meson interactions in a supernova remnant shell ejected prior to a gamma-ray burst provides a test for the precursor supernova, or supranova, model of gamma-ray bursts. Protons in the supernova remnant shell and photons entrapped from a supernova explosion or a pulsar wind from a fast-rotating neutron star remnant provide ample targets for protons escaping the internal shocks of the gamma-ray burst to interact and produce high energy neutrinos. We calculate the expected neutrino fluxes, which can be detected by current and future experiments.

  7. First search for neutrinos in correlation with gamma-ray bursts with the ANTARES neutrino telescope

    SciTech Connect

    2013-03-01

    A search for neutrino-induced muons in correlation with a selection of 40 gamma-ray bursts that occurred in 2007 has been performed with the ANTARES neutrino telescope. During that period, the detector consisted of 5 detection lines. The ANTARES neutrino telescope is sensitive to TeV–PeV neutrinos that are predicted from gamma-ray bursts. No events were found in correlation with the prompt photon emission of the gamma-ray bursts and upper limits have been placed on the flux and fluence of neutrinos for different models.

  8. BeppoSAX/Ulysses observations of cosmic gamma-ray bursts

    SciTech Connect

    Hurley, K.; Cline, T.; Frontera, F.; Dal Fiume, D.; Orlandini, M.

    1998-05-16

    BeppoSAX has been added to the 3rd Interplanetary Network of gamma-ray burst detectors. Of the {approx_equal}8 events observed to date by Ulysses and the BeppoSAX Gamma-Ray Burst Monitor (GRBM), four have been localized by triangulation, resulting in annuli whose 3 {sigma} widths are as small as 63{sup ''}. These data give error boxes whose sizes can be as much as an order of magnitude smaller than those obtained with the SAX Wide Field Camera (WFC). They can be used to confirm the association between fading X-ray and optical sources and gamma-ray bursts.

  9. Gamma-Ray Bursts: The Most Powerful Cosmic Explosions

    NASA Astrophysics Data System (ADS)

    van den Heuvel, E. P. J.

    The field of Gamma Ray Burst (GRB) research is one in which discovery by serendipity plays an important role. Serendipity in general means: one searches for something but finds something else, which often is more interesting. Generally in astrophysics this comes about because one has a new instrument that can measure some physical aspect at least an order of magnitude better than was possible before. For example, the new instrument has an order of magnitude better sensitivity, or spectral resolution or angular resolution. The discovery of the GRBs was itself a classical example of serendipity. They were discovered in 1967 with the US military Vela satellites, which had been built to monitor whether countries were keeping to the Nuclear Test Ban Treaty that had been signed earlier in the sixties. To this end the Vela satellites were built to be sensitive to the gamma ray flash of nuclear explosions in the Earth's atmosphere or in space. To check for possible radioactivity produced by explosions on the backside of the Moon, the Vela satellites had very wide orbits extending halfway to the Moon. There were always several of them orbiting the Earth at any given time. In 1967 they detected gamma ray flashes of much longer duration than expected from a nuclear explosion, and from the differences in arrival time of these flashes in the different Vela satellites the Los Alamos scientists could roughly determine the direction from which the flashes came. It turned out that they did not come from Earth but from the sky. The discoverers were so surprised by this result that they studied the bursts for a long time, until they were absolutely sure that this was a real phenomenon. In 1973 they presented their discovery to an astrophysical audience [33], which caused a sensation. Theorists produced dozens of theories about their possible origin, ranging from comets colliding with neutron stars to nuclear wars of extraterrestrial civilizations. For 30 years the places of origin of

  10. A Nontriggered Burst Supplement to the BATSE Gamma-Ray Burst Catalogs

    NASA Technical Reports Server (NTRS)

    Kommers, Jefferson M.; Lewin, Walter H. G.; Kouveliotou, Chryssa; vanParadijs, Jan; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.

    2001-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) with a real-time burst detection (or "trigger") system running onboard the spacecraft. Under some circumstances, however, a GRB may not activate the on-board burst trigger. For example, the burst may be too faint to exceed the on-board detection threshold, or it may occur while the on-board burst trigger is disabled for technical reasons. This paper describes a catalog of 873 "nontriggered" GRBs that were detected in a search of the archival continuous data from BATSE recorded between 1991 December 9.0 and 1997 December 17.0. For each burst, the catalog gives an estimated source direction, duration, peak flux, and fluence. Similar data are presented for 50 additional bursts of unknown origin that were detected in the 25-50 keV range; these events may represent the low-energy "tail" of the GRB spectral distribution. This catalog increases the number of GRBs detected with BATSE by 48% during the time period covered by the search.

  11. A Nontriggered Burst Supplement to the BATSE Gamma-Ray Burst Catalogs

    NASA Technical Reports Server (NTRS)

    Kommers, Jefferson M.; Lewin, Walter H. G.; Kouveliotou, Chryssa; vanParadijs, Jan; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.

    2001-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) with a real-time burst detection (or "trigger") system running onboard the spacecraft. Under some circumstances, however, a GRB may not activate the on-board burst trigger. For example, the burst may be too faint to exceed the on-board detection threshold, or it may occur while the on-board burst trigger is disabled for technical reasons. This paper describes a catalog of 873 "nontriggered" GRBs that were detected in a search of the archival continuous data from BATSE recorded between 1991 December 9.0 and 1997 December 17.0. For each burst, the catalog gives an estimated source direction, duration, peak flux, and fluence. Similar data are presented for 50 additional bursts of unknown origin that were detected in the 25-50 keV range; these events may represent the low-energy "tail" of the GRB spectral distribution. This catalog increases the number of GRBs detected with BATSE by 48% during the time period covered by the search.

  12. Gamma-ray bursts from massive Population-III stars: clues from the radio band

    NASA Astrophysics Data System (ADS)

    Burlon, D.; Murphy, T.; Ghirlanda, G.; Hancock, P. J.; Parry, R.; Salvaterra, R.

    2016-07-01

    Current models suggest gamma-ray bursts could be used as a way of probing Population-III stars - the first stars in the early Universe. In this paper, we use numerical simulations to demonstrate that late-time radio observations of gamma-ray burst afterglows could provide a means of identifying bursts that originate from Population-III stars, if these were highly massive, independently from their redshift. We then present the results from a pilot study using the Australia Telescope Compact Array at 17 GHz, designed to test the hypothesis that there may be Population-III gamma-ray bursts amongst the current sample of known events. We observed three candidates plus a control gamma-ray burst, and make no detections with upper limits of 20-40 μJy at 500-1300 d post-explosion.

  13. PROGRESS ON MARGIE, A GAMMA-RAY BURST ULTRA-LONG DURATION BALLOON MISSION

    SciTech Connect

    D. BAND; ET AL

    2001-02-01

    We are designing the Minute of Arc Resolution Gamma-ray Imaging Experiment (MARGIE) as a 100 day Ultra Long Duration Balloon (ULDB) mission to: (1) detect and localize gamma-ray bursts; and (2) survey the hard X-ray sky. Major advances in designing the CZT detectors increase the sensitivity to higher energy. Design of the gondola has also progressed.

  14. High-entropy fireballs and jets in gamma-ray burst sources

    NASA Technical Reports Server (NTRS)

    Meszaros, P.; Rees, M. J.

    1992-01-01

    Two mechanisms whereby compact coalescing binaries can produce relatively 'clean' fireballs via neutrino-antineutrino annihilation are proposed. Preejected mass due to tidal heating will collimate the fireball into jets. The resulting anisotropic gamma-ray emission can be efficient and intense enough to provide an acceptable model for gamma-ray bursts, if these originate at cosmological distances.

  15. Terrestrial Gamma-ray Flash (TGF) Observations with the Gamma-ray Burst Monitor on the Fermi Observatory

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2009-01-01

    Terrestrial Gamma-ray Flashes (TGFs) have now been detected with four different orbiting spacecraft. The latest observations are being made with the scintillation detectors of Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope Observatory (Fermi). Although this experiment was designed and optimized for the observation of cosmic gamma-ray bursts (GRBs), it has unprecedented capabilities for TGF observations, surpassing those of the experiment that discovered TGFs, the BATSE experiment on the Compton Gamma-ray Observatory. Launched in June 2008 from the Kennedy Space Center, the Fermi-GBM has been detecting about one TGF every four weeks. The thick bismuth germinate (BGO) scintillation detectors of the GBM have now observed photon energies from TGFs at energies up to approx.40 MeV. Individual photons are detected with an absolute timing accuracy of 2 microsec. Unlike the BATSE instrument, the GBM data system allows higher counting rates to be recorded and deadtime characteristics are well-known and correctable; thus the saturation effects seen with BATSE are avoided. TGF pulses as narrow as approx.0.1ms have been observed with the GBM. Like BATSE (and unlike RHESSI) an on-board trigger is required to detect TGFs. The minimum time window for this trigger is 16ms. A trigger window this wide greatly reduces the number of detected TGFs, since they most often have a much shorter duration than this window, thus reducing the signal-to-background. New on-board trigger algorithms based on detected photon energies are about to be implemented; this should increase the number of TGF triggers. High-energy spectra from TGFs observed with Fermi-GBM will be described.

  16. Terrestrial Gamma-ray Flash (TGF) Observations with the Gamma-ray Burst Monitor on the Fermi Observatory

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2009-01-01

    Terrestrial Gamma-ray Flashes (TGFs) have now been detected with four different orbiting spacecraft. The latest observations are being made with the scintillation detectors of Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope Observatory (Fermi). Although this experiment was designed and optimized for the observation of cosmic gamma-ray bursts (GRBs), it has unprecedented capabilities for TGF observations, surpassing those of the experiment that discovered TGFs, the BATSE experiment on the Compton Gamma-ray Observatory. Launched in June 2008 from the Kennedy Space Center, the Fermi-GBM has been detecting about one TGF every four weeks. The thick bismuth germinate (BGO) scintillation detectors of the GBM have now observed photon energies from TGFs at energies up to approx.40 MeV. Individual photons are detected with an absolute timing accuracy of 2 microsec. Unlike the BATSE instrument, the GBM data system allows higher counting rates to be recorded and deadtime characteristics are well-known and correctable; thus the saturation effects seen with BATSE are avoided. TGF pulses as narrow as approx.0.1ms have been observed with the GBM. Like BATSE (and unlike RHESSI) an on-board trigger is required to detect TGFs. The minimum time window for this trigger is 16ms. A trigger window this wide greatly reduces the number of detected TGFs, since they most often have a much shorter duration than this window, thus reducing the signal-to-background. New on-board trigger algorithms based on detected photon energies are about to be implemented; this should increase the number of TGF triggers. High-energy spectra from TGFs observed with Fermi-GBM will be described.

  17. Prompt gamma-ray burst emission from gradual magnetic dissipation

    NASA Astrophysics Data System (ADS)

    Beniamini, Paz; Giannios, Dimitrios

    2017-07-01

    We considered a model for the prompt phase of gamma-ray burst emission arising from a magnetized jet undergoing gradual energy dissipation due to magnetic reconnection. The dissipated magnetic energy is translated to bulk kinetic energy and to acceleration of particles. The energy in these particles is released via synchrotron radiation as they gyrate around the strong magnetic fields in the jet. At small radii, the optical depth is large, and the radiation is reprocessed through Comptonization into a narrow, strongly peaked component. At larger distances the optical depth becomes small and radiation escapes the jet with a non-thermal distribution. The obtained spectra typically peak around ≈300 keV (as observed) and with spectral indices below and above the peak that are, for a broad range of the model parameters, close to the observed values. The small radius of dissipation causes the emission to become self-absorbed at a few keV and can sufficiently suppress the optical and X-ray fluxes within the limits required by observations.

  18. Gamma-Ray Burst Associated Supernovae: Outliers Become Mainstream

    NASA Technical Reports Server (NTRS)

    Pian, E.; Mazzali, P.; Masetti, N.; Ferrero, P.; Klose, S.; Palazzi, E.; Ramirez-Ruiz, E.; Woosley, S. E.; Kouveliotou, C.; Deng, J.

    2006-01-01

    During the last eight years a clear connection has been established-between the two most powerful explosions in our Universe: core-collapse supernovae (SNe) and long gamma ray bursts (GRBs). Theory suggests4 that every GRB is simultaneously accompanied by a SN, but in only a few nearby cases have these two phenomena been observed together. We report the discovery and daily monitoring of SN 2006aj associated with the GRB 060218. Because the event was the second closest GRB, both explosions could be examined in detail. GRB 060218 had an unusually soft spectrum, long duration, and a total energy 100 to 1000 times less than most other GRBs. Yet SN 2006aj was similar to those in other GRBs, aside from rising more rapidly and being approximately 40% fainter. Taken together, these observations suggest that GRBs have two components: a broad, energetic, but only mildly relativistic outflow that makes a SN, and a more narrowly focused, highly relativistic jet responsible for the GRB. The properties of the GRB jet apparently vary greatly from event to event, while the broad SN outflow varies much less. Low energy transients like GRB 060218 may be the most common events in the Universe.

  19. Microphysics in the Gamma-Ray Burst Central Engine

    NASA Astrophysics Data System (ADS)

    Janiuk, Agnieszka

    2017-03-01

    We calculate the structure and evolution of a gamma-ray burst central engine where an accreting torus has formed around the newly born black hole. We study the general relativistic, MHD models and we self-consistently incorporate the nuclear equation of state. The latter accounts for the degeneracy of relativistic electrons, protons, and neutrons, and is used in the dynamical simulation, instead of a standard polytropic γ-law. The EOS provides the conditions for the nuclear pressure in the function of density and temperature, which evolve with time according to the conservative MHD scheme. We analyze the structure of the torus and outflowing winds, and compute the neutrino flux emitted through the nuclear reaction balance in the dense and hot matter. We also estimate the rate of transfer of the black-hole rotational energy to the bipolar jets. Finally, we elaborate on the nucleosynthesis of heavy elements in the accretion flow and the wind, through computations of the thermonuclear reaction network. We discuss the possible signatures of the radioactive element decay in the accretion flow. We suggest that further detailed modeling of the accretion flow in the GRB engine, together with its microphysics, may be a valuable tool to constrain the black-hole mass and spin. It can be complementary to the gravitational wave analysis if the waves are detected with an electromagnetic counterpart.

  20. COSMOLOGICAL PARAMETERS FROM SUPERNOVAE ASSOCIATED WITH GAMMA-RAY BURSTS

    SciTech Connect

    Li, Xue; Hjorth, Jens; Wojtak, Radosław

    2014-11-20

    We report estimates of the cosmological parameters Ω {sub m} and Ω{sub Λ} obtained using supernovae (SNe) associated with gamma-ray bursts (GRBs) at redshifts up to 0.606. Eight high-fidelity GRB-SNe with well-sampled light curves across the peak are used. We correct their peak magnitudes for a luminosity-decline rate relation to turn them into accurate standard candles with dispersion σ = 0.18 mag. We also estimate the peculiar velocity of the low-redshift host galaxy of SN 1998bw using constrained cosmological simulations. In a flat universe, the resulting Hubble diagram leads to best-fit cosmological parameters of (Ω{sub m},Ω{sub Λ})=(0.58{sub −0.25}{sup +0.22},0.42{sub −0.22}{sup +0.25}). This exploratory study suggests that GRB-SNe can potentially be used as standardizable candles to high redshifts to measure distances in the universe and constrain cosmological parameters.

  1. Superconducting Cosmic Strings as Gamma-Ray Burst Engines

    NASA Astrophysics Data System (ADS)

    Berezinsky, V.; Hnatyk, B.; Vilenkin, A.

    Loops of superconducting cosmic strings oscillating in interstellar or intergalactic magnetic fields develop ac currents and generate electromagnetic radiation. A powerful beamed pulse of large amplitude electromagnetic waves (LAEMWs) from a cusp naturally produces a relativistic jet of accelerated IGM or ISM particles, which creates GRB event. A single free parameter, the string scale of symmetry breaking {\\msf η ˜ 1014} GeV, together with reasonable assumptions about cosmic magnetic fields, provides the close to observed values of GRB rate, duration and fluence. This model predicts that GRBs are accompanied by strong bursts of gravitational radiation which should be detectable by LIGO, VIRGO and LISA detectors. Another prediction is the diffuse gamma-ray radiation at 8 MeV -- 100 GeV with a spectrum and flux comparable to the observed. The predicted rate of GRBs from galaxies is considerably smaller than observed one. This suggests that GRBs from cusps may be responsible for only a subset of the observed GRBs not associated with galaxies.

  2. The Maximum Isotropic Energy of Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Atteia, J.-L.; Heussaff, V.; Dezalay, J.-P.; Klotz, A.; Turpin, D.; Tsvetkova, A. E.; Frederiks, D. D.; Zolnierowski, Y.; Daigne, F.; Mochkovitch, R.

    2017-03-01

    The most energetic gamma-ray bursts (GRBs) are remarkable sources releasing huge amounts of energy on short timescales. Their prompt emission, which usually lasts a few seconds, is so bright that it is visible across the whole observable universe. Studying these extreme events may provide clues on the nature of GRB progenitors and on the physical processes at work in relativistic jets. In this paper, we study the bright end of the isotropic energy distribution of long GRBs. We use two samples of long GRBs with redshift detected by Fermi/GBM or Konus-Wind, two instruments that measure the spectral shape and the energetics of the prompt emission accurately. We focus on GRBs within a range of redshifts z = 1–5, a volume that contains a large number of energetic GRBs, and we propose a simple method to reconstruct the bright end of the GRB energy distribution from the observed one. We find that the GRB energy distribution cannot be described by a simple power law but requires a strong cutoff above 1{--}3× {10}54 erg. We attribute this feature to an intrinsic limit on the energy per unit of solid angle radiated by GRBs.

  3. Modeling Extragalactic Extinction through Gamma-Ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Zonca, Alberto; Cecchi-Pestellini, Cesare; Mulas, Giacomo; Casu, Silvia; Aresu, Giambattista

    2016-09-01

    We analyze extragalactic extinction profiles derived through gamma-ray burst afterglows, using a dust model specifically constructed on the assumption that dust grains are not immutable but respond, time-dependently, to the local physics. Such a model includes core-mantle spherical particles of mixed chemical composition (silicate core, sp2, and sp3 carbonaceous layers), and an additional molecular component in the form of free-flying polycyclic aromatic hydrocarbons. We fit most of the observed extinction profiles. Failures occur for lines of sight, presenting remarkable rises blueward of the bump. We find a tendency for the carbon chemical structure to become more aliphatic with the galactic activity, and to some extent with increasing redshifts. Moreover, the contribution of the molecular component to the total extinction is more important in younger objects. The results of the fitting procedure (either successes and failures) may be naturally interpreted through an evolutionary prescription based on the carbon cycle in the interstellar medium of galaxies.

  4. Gamma-ray burst flares: X-ray flaring. II

    SciTech Connect

    Swenson, C. A.; Roming, P. W. A.

    2014-06-10

    We present a catalog of 498 flaring periods found in gamma-ray burst (GRB) light curves taken from the online Swift X-Ray Telescope GRB Catalogue. We analyzed 680 individual light curves using a flare detection method developed and used on our UV/optical GRB Flare Catalog. This method makes use of the Bayesian Information Criterion to analyze the residuals of fitted GRB light curves and statistically determines the optimal fit to the light curve residuals in an attempt to identify any additional features. These features, which we classify as flares, are identified by iteratively adding additional 'breaks' to the light curve. We find evidence of flaring in 326 of the analyzed light curves. For those light curves with flares, we find an average number of ∼1.5 flares per GRB. As with the UV/optical, flaring in our sample is generally confined to the first 1000 s of the afterglow, but can be detected to beyond 10{sup 5} s. Only ∼50% of the detected flares follow the 'classical' definition of Δt/t ≤ 0.5, with many of the largest flares exceeding this value.

  5. Gamma-ray bursts and their use as cosmic probes

    PubMed Central

    2017-01-01

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

  6. Delayed energy injection model for gamma-ray burst afterglows

    SciTech Connect

    Geng, J. J.; Huang, Y. F.; Yu, Y. B.; Wu, X. F. E-mail: xfwu@pmo.ac.cn

    2013-12-10

    The shallow decay phase and flares in the afterglows of gamma-ray bursts (GRBs) are widely believed to be associated with the later activation of the central engine. Some models of energy injection involve a continuous energy flow since the GRB trigger time, such as the magnetic dipole radiation from a magnetar. However, in the scenario involving a black hole accretion system, the energy flow from the fall-back accretion may be delayed for a fall-back time ∼t {sub fb}. Thus, we propose a delayed energy injection model. The delayed energy would cause a notable rise to the Lorentz factor of the external shock, which will 'generate' a bump in the multiple band afterglows. If the delayed time is very short, our model degenerates to the previous models. Our model can explain the significant re-brightening in the optical and infrared light curves of GRB 081029 and GRB 100621A. A considerable fall-back mass is needed to provide the later energy; this indicates that GRBs accompanied with fall-back material may be associated with a low energy supernova so that the fraction of the envelope can survive during eruption. The fall-back time can give meaningful information on the properties of GRB progenitor stars.

  7. Broadband turbulent spectra in gamma-ray burst light curves

    SciTech Connect

    Van Putten, Maurice H. P. M.; Guidorzi, Cristiano; Frontera, Filippo

    2014-05-10

    Broadband power density spectra offer a window to understanding turbulent behavior in the emission mechanism and, at the highest frequencies, in the putative inner engines powering long gamma-ray bursts (GRBs). We describe a chirp search method alongside Fourier analysis for signal detection in the Poisson noise-dominated, 2 kHz sampled, BeppoSAX light curves. An efficient numerical implementation is described in O(Nnlog n) operations, where N is the number of chirp templates and n is the length of the light-curve time series, suited for embarrassingly parallel processing. For the detection of individual chirps over a 1 s duration, the method is one order of magnitude more sensitive in signal-to-noise ratio than Fourier analysis. The Fourier-chirp spectra of GRB 010408 and GRB 970816 show a continuation of the spectral slope with up to 1 kHz of turbulence identified in low-frequency Fourier analysis. The same continuation is observed in an average spectrum of 42 bright, long GRBs. An outlook on a similar analysis of upcoming gravitational wave data is included.

  8. On the radio afterglow of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Dado, S.; Dar, A.; De Rújula, A.

    2003-04-01

    We use the cannonball (CB) model of gamma ray bursts (GRBs) to predict the spectral and temporal behaviour of their radio afterglows (AGs). A single simple expression describes the AGs at all times and frequencies; its high-frequency limit reproduces the successful CB model predictions for optical and X-ray AGs. We analyze all of the observed radio AGs of GRBs with known redshifts, including those of the exceptionally close-by GRB 980425. We also study in detail the time-evolution of the AGs' spectral index. The agreement between theory and observations is excellent, even though the CB model is extremely frugal in the number of parameters required to explain the radio observations. We propose to use the scintillations in the radio AGs of GRBs to verify and measure the hyperluminal speed of their jetted CBs, whose apparent angular velocity is of the same order of magnitude as that of galactic pulsars, consistently measured directly, or via scintillations. Figures 6 to 55 are only available in electronic form at http://www.edpsciences.org

  9. Gamma-Ray Burst Supernovae as Standardizable Candles

    NASA Astrophysics Data System (ADS)

    Cano, Z.

    2014-10-01

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

  10. Testing a new view of gamma-ray burst afterglows

    NASA Astrophysics Data System (ADS)

    Nardini, M.; Ghisellini, G.; Ghirlanda, G.; Celotti, A.

    2010-04-01

    The optical and X-ray light curves of long gamma-ray bursts (GRBs) often show a complex evolution and in most cases do not track each other. This behaviour cannot be easily explained by the simplest standard afterglow models. A possible interpretation is to consider the observed optical and X-ray light curves as the sum of two separate components. This scenario requires the presence of a spectral break between these bands. One of the aims of this work is to test whether such a break is present within the observed Swift X-Ray Telescope energy range. We analyse the X-ray afterglow spectra of a sample of 33 long GRBs with known redshift, good optical photometry and published estimate of the host galaxy dust absorption AhostV. We find that indeed in seven bright events a broken power law provides a fit to the data that is better than a single power-law model. For eight events, instead, the X-ray spectrum is better fitted by a single power law. We discuss the role of these breaks in connection to the relation between the host hydrogen column density NhostH and AhostV and check the consistency of the X-ray spectral breaks with the optical bands photometry. We analyse the optical to X-ray spectral energy distributions at different times and find again consistency with two components interpretation.

  11. Gamma-ray burst jets: uniform or structured?

    NASA Astrophysics Data System (ADS)

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

    The structure of Gamma-Ray Burst (GRB) jets impacts on their prompt and afterglow emission properties. Insights into the still unknown structure of GRBs can be achieved by studying how different structures impact on the luminosity function (LF): i) we show that low ($10^{46} < L_{\\rm iso} < 10^{48}$ erg/s) and high (i.e. with $L_{\\rm iso} > 10^{50}$ erg/s) luminosity GRBs can be described by a unique LF; ii) we find that a uniform jet (seen on- and off-axis) as well as a very steep structured jet (i.e. $\\epsilon(\\theta) \\propto \\theta^{-s}$ with $s > 4$) can reproduce the current LF data; iii) taking into account the emission from the whole jet (i.e. including contributions from mildly relativistic, off-axis jet elements) we find that $E_{\\rm iso}(\\theta_{\\rm v})$ (we dub this quantity "apparent structure") can be very different from the intrinsic structure $\\epsilon(\\theta)$: in particular, a jet with a Gaussian intrinsic structure has an apparent structure which is more similar to a power law. This opens a new viewpoint on the quasi-universal structured jet hypothesis.

  12. Luminosity function and jet structure of Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    The structure of gamma-ray burst (GRB) jets impacts on their prompt and afterglow emission properties. The jet of GRBs could be uniform, with constant energy per unit solid angle within the jet aperture, or it could be structured, namely with energy and velocity that depend on the angular distance from the axis of the jet. We try to get some insight about the still unknown structure of GRBs by studying their luminosity function. We show that low (1046-48 erg s-1) and high (i.e. with L ≥ 1050 erg s-1) luminosity GRBs can be described by a unique luminosity function, which is also consistent with current lower limits in the intermediate luminosity range (1048-50 erg s-1). We derive analytical expressions for the luminosity function of GRBs in uniform and structured jet models and compare them with the data. Uniform jets can reproduce the entire luminosity function with reasonable values of the free parameters. A structured jet can also fit adequately the current data, provided that the energy within the jet is relatively strongly structured, i.e. E ∝ θ-k with k ≥ 4. The classical E ∝ θ-2 structured jet model is excluded by the current data.

  13. VLBI of supernovae and gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Bartel, N.; Karimi, B.; Bietenholz, M. F.

    2017-04-01

    Supernovae and gamma-ray bursts (GRBs) are among the brightest events in the universe. Excluding Type Ia supernovae and short GRBs, they are the result of the core collapse of a massive star with material being ejectedwith speeds of several 1000 km/s to nearly the speed of light, and with a neutron star or a black hole left over as the compact remnant of the explosion. Synchrotron radiation in the radio is generated in a shell when the ejecta interact with the surrounding medium and possibly also in the central region near the compact remnant itself. VLBI has allowed resolving some of these sources and monitoring their expansion in detail, thereby revealing characteristics of the dying star, the explosion, the expanding shock front, and the expected compact remnant. We report on updates of some of the most interesting results that have been obtained with VLBI so far. Movies of supernovae are available from our website. They show the evolution from shortly after the explosion to decades thereafter, in one case revealing an emerging compact central source, which may be associated with shock interaction near the explosion center or with the stellar corpse itself, a neutron star or a black hole.

  14. Flares in gamma-ray bursts: disc fragmentation and evolution

    NASA Astrophysics Data System (ADS)

    Dall'Osso, Simone; Perna, Rosalba; Tanaka, Takamitsu L.; Margutti, Raffaella

    2017-02-01

    Flaring activity following gamma-ray bursts (GRBs), observed in both long and short GRBs, signals a long-term activity of the central engine. However, its production mechanism has remained elusive. Here, we develop a quantitative model of the idea proposed by Perna et al. of a disc whose outer regions fragment due to the onset of gravitational instability. The self-gravitating clumps migrate through the disc and begin to evolve viscously when tidal and shearing torques break them apart. Our model consists of two ingredients: theoretical bolometric flare light curves whose shape (width, skewness) is largely insensitive to the model parameters, and a spectral correction to match the bandpass of the available observations, that is calibrated using the observed spectra of the flares. This simple model reproduces, with excellent agreement, the empirical statistical properties of the flares as measured by their width-to-arrival time ratio and skewness (ratio between decay and rise time). We present model fits to the observed light curves of two well-monitored flares, GRB 060418 and GRB 060904B. To the best of our knowledge, this is the first quantitative model able to reproduce the flare light curves and explain their global statistical properties.

  15. Cosmic gamma-ray bursts from BATSE - Another great debate

    NASA Technical Reports Server (NTRS)

    Hartmann, Dieter H.; The, Lih-Sin; Clayton, Donald D.; Schnepf, Neil G.; Linder, Eric V.

    1992-01-01

    The BATSE detectors aboard Compton Observatory record about one cosmic gamma-ray burst (GRB) per day. Preliminary data analysis shows a highly isotropic sky map and a nonuniform brightness distribution. Anisotropies expected from a Galactic neutron star population, the most frequently considered source model, did not emerge from the data. Taken at face value, the data seem to suggest a heliocentric solution of the GRB puzzle. The observed isotropy can be achieved if sources are either very near or extragalactic. Pop I neutron stars in the disk do not simultaneously fit sky and brightness distributions. A possibility are sources in an extended Galactic halo with scale length large enough to avoid strong anisotropies due to the solar offset from the Galactic center. If GRBs are located in an extended halo we ask whether the neutron star paradigm can survive. We show that the recently discovered high velocity radio pulsars may provide a natural source population for GRBs. If these pulsars formed in the halo, as suggested by the radio data, the possibility arises that GRBs and high velocity pulsars are two related phenomena that provide observational evidence of the dark Galactic corona. We also discuss cosmological redshift constraints that follow from the observed brightness distribution.

  16. MAGNETIZATION DEGREE OF GAMMA-RAY BURST FIREBALLS: NUMERICAL STUDY

    SciTech Connect

    Harrison, Richard; Kobayashi, Shiho

    2013-08-01

    The relative strength between forward and reverse shock emission in early gamma-ray burst (GRB) afterglow reflects that of magnetic energy densities in the two shock regions. We numerically show that with the current standard treatment, the fireball magnetization is underestimated by up to two orders of magnitude. This discrepancy is especially large in the sub-relativistic reverse shock regime (i.e., the thin shell and intermediate regime), where most optical flashes were detected. We provide new analytic estimates of the reverse shock emission based on a better shock approximation, which well describe numerical results in the intermediate regime. We show that the reverse shock temperature at the onset of afterglow is constant, ( {Gamma}-bar{sub d}-1){approx}8 Multiplication-Sign 10{sup -2}, when the dimensionless parameter {xi}{sub 0} is more than several. Our approach is applied to case studies of GRB 990123 and 090102, and we find that magnetic fields in the fireballs are even stronger than previously believed. However, these events are still likely to be due to a baryonic jet with {sigma} {approx} 10{sup -3} for GRB 990123 and {approx}3 Multiplication-Sign 10{sup -4} to 3 for GRB 090102.

  17. Gamma-Ray Burst Associated Supernovae: Outliers Become Mainstream

    NASA Technical Reports Server (NTRS)

    Pian, E.; Mazzali, P.; Masetti, N.; Ferrero, P.; Klose, S.; Palazzi, E.; Ramirez-Ruiz, E.; Woosley, S. E.; Kouveliotou, C.; Deng, J.

    2006-01-01

    During the last eight years a clear connection has been established-between the two most powerful explosions in our Universe: core-collapse supernovae (SNe) and long gamma ray bursts (GRBs). Theory suggests4 that every GRB is simultaneously accompanied by a SN, but in only a few nearby cases have these two phenomena been observed together. We report the discovery and daily monitoring of SN 2006aj associated with the GRB 060218. Because the event was the second closest GRB, both explosions could be examined in detail. GRB 060218 had an unusually soft spectrum, long duration, and a total energy 100 to 1000 times less than most other GRBs. Yet SN 2006aj was similar to those in other GRBs, aside from rising more rapidly and being approximately 40% fainter. Taken together, these observations suggest that GRBs have two components: a broad, energetic, but only mildly relativistic outflow that makes a SN, and a more narrowly focused, highly relativistic jet responsible for the GRB. The properties of the GRB jet apparently vary greatly from event to event, while the broad SN outflow varies much less. Low energy transients like GRB 060218 may be the most common events in the Universe.

  18. The dyadosphere of black holes and gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Preparata, Giuliano; Ruffini, Remo; Xue, She-Sheng

    1998-10-01

    The ``dyadosphere" has been defined (Ruffini \\cite{r2}, Preparata et al. \\cite{prx}) as the region outside the horizon of a black hole endowed with an electromagnetic field (abbreviated to EMBH for ``electromagnetic black hole") where the electromagnetic field exceeds the critical value, predicted by Heisenberg & Euler (\\cite{he}) for e(+) e(-) pair production. In a very short time ( ~ O / mc(2),) a very large number of pairs is created there. We here give limits on the EMBH parameters leading to a Dyadosphere for 10M_{\\odot} and 10^5M_{\\odot} EMBH's, and give as well the pair densities as functions of the radial coordinate. We here assume that the pairs reach thermodynamic equilibrium with a photon gas and estimate the average energy per pair as a function of the EMBH mass. These data give the initial conditions for the analysis of an enormous pair-electromagnetic-pulse or ``P.E.M. pulse" which naturally leads to relativistic expansion. Basic energy requirements for gamma ray bursts (GRB), including GRB971214 recently observed at z=3.4$, can be accounted for by processes occurring in the dyadosphere. In this letter we do not address the problem of forming either the EMBH or the dyadosphere: we establish some inequalities which must be satisfied during their formation process.

  19. GAMMA-RAY BURSTS FROM MAGNETIZED COLLISIONALLY HEATED JETS

    SciTech Connect

    Vurm, Indrek; Beloborodov, Andrei M.; Poutanen, Juri E-mail: juri.poutanen@oulu.fi

    2011-09-01

    Jets producing gamma-ray bursts (GRBs) are likely to carry a neutron component that drifts with respect to the proton component. The neutron-proton collisions strongly heat the jet and generate electron-positron pairs. We investigate radiation produced by this heating using a new numerical code. Our results confirm the recent claim that collisional heating generates the observed Band-type spectrum of GRBs. We extend the model to study the effects of magnetic fields on the emitted spectrum. We find that the spectrum peak remains near 1 MeV for the entire range of the magnetization parameter 0 < {epsilon}{sub B} < 2 that is explored in our simulations. The low-energy part of the spectrum softens with increasing {epsilon}{sub B}, and a visible soft excess appears in the keV band. The high-energy part of the spectrum extends well above the GeV range and can contribute to the prompt emission observed by Fermi/LAT. Overall, the radiation spectrum created by the collisional mechanism appears to agree with observations, with no fine tuning of parameters.

  20. DIFFUSE PeV NEUTRINOS FROM GAMMA-RAY BURSTS

    SciTech Connect

    Liu, Ruo-Yu; Wang, Xiang-Yu

    2013-04-01

    The IceCube Collaboration recently reported the potential detection of two cascade neutrino events in the energy range 1-10 PeV. We study the possibility that these PeV neutrinos are produced by gamma-ray bursts (GRBs), paying special attention to the contribution by untriggered GRBs that elude detection due to their low photon flux. Based on the luminosity function, rate distribution with redshift and spectral properties of GRBs, we generate, using a Monte Carlo simulation, a GRB sample that reproduces the observed fluence distribution of Fermi/GBM GRBs and an accompanying sample of untriggered GRBs simultaneously. The neutrino flux of every individual GRB is calculated in the standard internal shock scenario, so that the accumulative flux of the whole samples can be obtained. We find that the neutrino flux in PeV energies produced by untriggered GRBs is about two times higher than that produced by the triggered ones. Considering the existing IceCube limit on the neutrino flux of triggered GRBs, we find that the total flux of triggered and untriggered GRBs can reach at most a level of {approx}10{sup -9} GeV cm{sup -2} s{sup -1} sr{sup -1}, which is insufficient to account for the reported two PeV neutrinos. Possible contributions to diffuse neutrinos by low-luminosity GRBs and the earliest population of GRBs are also discussed.

  1. 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.

  2. 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.; hide

    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.

  3. 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.; hide

    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.

  4. Gamma-ray burst supernovae as standardizable candles

    SciTech Connect

    Cano, Z.

    2014-10-20

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

  5. APPLICATION OF JITTER RADIATION: GAMMA-RAY BURST PROMPT POLARIZATION

    SciTech Connect

    Mao, Jirong; Wang, Jiancheng

    2013-10-10

    A high degree of polarization of gamma-ray burst (GRB) prompt emission has been confirmed in recent years. In this paper, we apply jitter radiation to study the polarization feature of GRB prompt emission. In our framework, relativistic electrons are accelerated by turbulent acceleration. Random and small-scale magnetic fields are generated by turbulence. We further determine that the polarization property of GRB prompt emission is governed by the configuration of the random and small-scale magnetic fields. A two-dimensional compressed slab, which contains a stochastic magnetic field, is applied in our model. If the jitter condition is satisfied, the electron deflection angle in the magnetic field is very small and the electron trajectory can be treated as a straight line. A high degree of polarization can be achieved when the angle between the line of sight and the slab plane is small. Moreover, micro-emitters with mini-jet structures are considered to be within a bulk GRB jet. The jet 'off-axis' effect is intensely sensitive to the observed polarization degree. We discuss the depolarization effect on GRB prompt emission and afterglow. We also speculate that the rapid variability of GRB prompt polarization may be correlated with the stochastic variability of the turbulent dynamo or the magnetic reconnection of plasmas.

  6. R-process in Supernovae and Gamma-Ray Bursts

    SciTech Connect

    Kajino, T.; Harikae, S.; Yoshida, T.; Nakamura, K.; Aoki, W.

    2010-05-12

    We study r-process nucleosynthesis in neutrino-driven winds of Type II supernovae (SNe), binary neutron-star mergers, and magneto-hydrodynamic jets in view of recent astronomical observations of r-process elements in metal-deficient stars and new nuclear reaction data. Universality in observed abundance pattern and total ejected yields of the r-elements from single episode of each candidate site are used to identify the astrophysical site of the r-process. Neutrinos play the critical roles in light element synthesis as well as r-process. Elemental abundances are affected strongly by neutrino oscillations (MSW effect) through the SN nu-process nucleosynthesis. We find that unknown neutrino oscillation parameters, i.e. mass hierarchy and mixing angle theta{sub 13}, are simultaneously constrained by the Li/B ratio from SN nucleosynthesis. Gamma ray burst (GRB) nucleosynthesis in contrast is expected to be relatively free from thermal neutrino effects because of black hole (BH) formation instead of neutron star. We find that the abundance pattern is totally different from ordinary SN nucleosynthesis.

  7. Radiative striped wind model for gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Bégué, D.; Pe'er, A.; Lyubarsky, Y.

    2017-01-01

    In this paper we revisit the striped wind model in which the wind is accelerated by magnetic reconnection. In our treatment, radiation is included as an independent component, and two scenarios are considered. In the first one, radiation cannot stream efficiently through the reconnection layer, while the second scenario assumes that radiation is homogeneous in the striped wind. We show how these two assumptions affect the dynamics. In particular, we find that the asymptotic radial evolution of the Lorentz factor is not strongly modified whether radiation can stream through the reconnection layer or not. On the other hand, we show that the width, density and temperature of the reconnection layer are strongly dependent on these assumptions. We then apply the model to the gamma-ray burst context and find that photons cannot diffuse efficiently through the reconnection layer below radius r_D^{Δ } ˜ 10^{10.5} cm, which is about an order of magnitude below the photospheric radius. Above r_D^{Δ }, the dynamics asymptotes to the solution of the scenario in which radiation can stream through the reconnection layer. As a result, the density of the current sheet increases sharply, providing efficient photon production by the Bremsstrahlung process which could have profound influence on the emerging spectrum. This effect might provide a solution to the soft photon problem in GRBs.

  8. Identifying high-redshift gamma-ray bursts with RATIR

    SciTech Connect

    Littlejohns, O. M.; Butler, N. R.; Cucchiara, A.; Watson, A. M.; Lee, W. H.; Richer, M. G.; De Diego, J. A.; Georgiev, L.; González, J.; Román-Zúñiga, C. G.; Kutyrev, A. S.; Troja, E.; Gehrels, N.; Moseley, H.; Klein, C. R.; Fox, O. D.; Bloom, J. S.; Prochaska, J. X.; Ramirez-Ruiz, E.

    2014-07-01

    We present a template-fitting algorithm for determining photometric redshifts, z {sub phot}, of candidate high-redshift gamma-ray bursts (GRBs). Using afterglow photometry, obtained by the Reionization and Transients InfraRed (RATIR) camera, this algorithm accounts for the intrinsic GRB afterglow spectral energy distribution, host dust extinction, and the effect of neutral hydrogen (local and cosmological) along the line of sight. We present the results obtained by this algorithm and the RATIR photometry of GRB 130606A, finding a range of best-fit solutions, 5.6 < z {sub phot} < 6.0, for models of several host dust extinction laws (none, the Milky Way, Large Magellanic Clouds, and Small Magellanic Clouds), consistent with spectroscopic measurements of the redshift of this GRB. Using simulated RATIR photometry, we find that our algorithm provides precise measures of z {sub phot} in the ranges of 4 < z {sub phot} ≲ 8 and 9 < z {sub phot} < 10 and can robustly determine when z {sub phot} > 4. Further testing highlights the required caution in cases of highly dust-extincted host galaxies. These tests also show that our algorithm does not erroneously find z {sub phot} < 4 when z {sub sim} > 4, thereby minimizing false negatives and allowing us to rapidly identify all potential high-redshift events.

  9. The physics of gamma-ray bursts & relativistic jets

    NASA Astrophysics Data System (ADS)

    Kumar, Pawan; Zhang, Bing

    2015-02-01

    We provide a comprehensive review of major developments in our understanding of gamma-ray bursts, with particular focus on the discoveries made within the last fifteen years when their true nature was uncovered. We describe the observational properties of photons from the radio to 100s GeV bands, both in the prompt emission and the afterglow phases. Mechanisms for the generation of these photons in GRBs are discussed and confronted with observations to shed light on the physical properties of these explosions, their progenitor stars and the surrounding medium. After presenting observational evidence that a powerful, collimated, jet moving at close to the speed of light is produced in these explosions, we describe our current understanding regarding the generation, acceleration, and dissipation of the jet. We discuss mounting observational evidence that long duration GRBs are produced when massive stars die, and that at least some short duration bursts are associated with old, roughly solar mass, compact stars. The question of whether a black-hole or a strongly magnetized, rapidly rotating neutron star is produced in these explosions is also discussed. We provide a brief summary of what we have learned about relativistic collisionless shocks and particle acceleration from GRB afterglow studies, and discuss the current understanding of radiation mechanism during the prompt emission phase. We discuss theoretical predictions of possible high-energy neutrino emission from GRBs and the current observational constraints. Finally, we discuss how these explosions may be used to study cosmology, e.g. star formation, metal enrichment, reionization history, as well as the formation of first stars and galaxies in the universe.

  10. Gamma-ray bursts in the comoving frame

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Nava, L.; Ghisellini, G.; Celotti, A.; Burlon, D.; Covino, S.; Melandri, A.

    2012-02-01

    We estimate the bulk Lorentz factor Γ0 of 31 gamma-ray bursts (GRBs) using the measured peak time of their afterglow light curves. We consider two possible scenarios for the estimate of Γ0: the case of a homogeneous circumburst medium or a wind density profile. The values of Γ0 are broadly distributed between few tens and several hundreds with average values ˜138 and ˜66 for the homogeneous and wind density profile, respectively. We find that the isotropic energy and luminosity correlate in a similar way with Γ0, i.e. ? and ?, while the peak energy Epeak∝Γ0. These correlations are less scattered in the wind density profile than in the homogeneous case. We then study the energetics, luminosities and spectral properties of our bursts in their comoving frame. The distribution of ? is very narrow with a dispersion of less than a decade in the wind case, clustering around ? erg s-1. Peak photon energies cluster around ?˜ 6 keV. The newly found correlations involving Γ0 offer a general interpretation scheme for the spectral energy correlation of GRBs. The Epeak-Eiso and Epeak-Liso correlations are due to the different Γ0 factors and the collimation-corrected correlation, Epeak-Eγ (obtained by correcting the isotropic quantities for the jet opening angle θj), can be explained if ?= constant. Assuming the Epeak-Eγ correlation as valid, we find a typical value of θjΓ0˜ 6-20, in agreement with the predictions of magnetically accelerated jet models.

  11. Accessing the population of high-redshift Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Ghirlanda, G.; Salvaterra, R.; Ghisellini, G.; Mereghetti, S.; Tagliaferri, G.; Campana, S.; Osborne, J. P.; O'Brien, P.; Tanvir, N.; Willingale, D.; Amati, L.; Basa, S.; Bernardini, M. G.; Burlon, D.; Covino, S.; D'Avanzo, P.; Frontera, F.; Götz, D.; Melandri, A.; Nava, L.; Piro, L.; Vergani, S. D.

    2015-04-01

    Gamma Ray Bursts (GRBs) are a powerful probe of the high-redshift Universe. We present a tool to estimate the detection rate of high-z GRBs by a generic detector with defined energy band and sensitivity. We base this on a population model that reproduces the observed properties of GRBs detected by Swift, Fermi and CGRO in the hard X-ray and γ-ray bands. We provide the expected cumulative distributions of the flux and fluence of simulated GRBs in different energy bands. We show that scintillator detectors, operating at relatively high energies (e.g. tens of keV to the MeV), can detect only the most luminous GRBs at high redshifts due to the link between the peak spectral energy and the luminosity (Epeak-Liso) of GRBs. We show that the best strategy for catching the largest number of high-z bursts is to go softer (e.g. in the soft X-ray band) but with a very high sensitivity. For instance, an imaging soft X-ray detector operating in the 0.2-5 keV energy band reaching a sensitivity, corresponding to a fluence, of ˜10-8 erg cm-2 is expected to detect ≈40 GRBs yr-1 sr-1 at z ≥ 5 (≈3 GRBs yr-1 sr-1 at z ≥ 10). Once high-z GRBs are detected the principal issue is to secure their redshift. To this aim we estimate their NIR afterglow flux at relatively early times and evaluate the effectiveness of following them up and construct usable samples of events with any forthcoming GRB mission dedicated to explore the high-z Universe.

  12. The pulse luminosity function of Swift gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Amaral-Rogers, A.; Willingale, R.; O'Brien, P. T.

    2017-01-01

    The complete Swift Burst Alert Telescope and X-Ray Telescope light curves of 118 gamma-ray bursts (GRBs) with known redshifts were fitted using the physical model of GRB pulses by Willingale et al. to produce a total of 607 pulses. We compute the pulse luminosity function utilizing three GRB formation rate models: a progenitor that traces the cosmic star formation rate density (CSFRD) with either a single population of GRBs, coupled to various evolutionary parameters, or a bimodal population of high- and low-luminosity GRBs; and a direct fit to the GRB formation rate excluding any a priori assumptions. We find that a single population of GRB pulses with an evolving luminosity function is preferred over all other univariate evolving GRB models, or bimodal luminosity functions in reproducing the observed GRB pulse L-z distribution and that the magnitude of the evolution in brightness is consistent with studies that utilize only the brightest GRB pulses. We determine that the appearance of a GRB formation rate density evolution component is an artefact of poor parametrization of the CSFRD at high redshifts rather than indicating evolution in the formation rate of early epoch GRBs. We conclude that the single brightest region of a GRB light curve holds no special property; by incorporating pulse data from the totality of GRB emission we boost the GRB population statistics by a factor of 5, rule out some models utilized to explain deficiencies in GRB formation rate modelling, and constrain more tightly some of the observed parameters of GRB behaviour.

  13. PROBING EXTRAGALACTIC DUST THROUGH NEARBY GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Liang, S. L.; Li Aigen E-mail: lia@missouri.ed

    2010-02-10

    The quantities and wavelength dependencies of the dust extinction along the lines of sight toward 33 nearby gamma-ray bursts (GRBs) with redshifts z < 2 are derived from fitting their afterglow spectral energy distributions. Unlike previous studies which often assume a specific extinction law like that of the Milky Way (MW) and the Large and Small Magellanic Clouds (LMC/SMC), our approach-we call it the 'Drude' approach-is more flexible in determining the true wavelength dependence of the extinction (while the shape of the extinction curve inferred from that relying on a priori assumption of a template extinction law is, of course, fixed). The extinction curves deduced from the Drude approach display a wide diversity of shapes, ranging from relatively flat curves to curves which are featureless and steeply rise toward the far-ultraviolet, and from curves just like that of the MW, LMC, and SMC to curves resembling that of the MW and LMC but lacking the 2175 A bump. The visual extinction A{sub V} derived from the Drude approach is generally larger by a factor of {approx}2-5 than that inferred by assuming a SMC-type template extinction law. Consistent with previous studies, the extinction-to-gas ratio is mostly smaller than that of the MW, and does not seem to correlate with the shape of the extinction curve. It is shown that the standard silicate-graphite interstellar grain model closely reproduces the extinction curves of all 33 GRBs host galaxies. For these 33 bursts at z < 2, we find no evidence for the evolution of the dust extinction, dust sizes, and relative abundances of silicate to graphite on redshifts.

  14. Calibration of gamma-ray burst luminosity indicators

    NASA Astrophysics Data System (ADS)

    Liang, Enwei; Zhang, Bing

    2006-06-01

    Several gamma-ray burst (GRB) luminosity indicators have been proposed which can be generally written in the form of , where c is the coefficient, xi is the ith observable, and ai is its corresponding power-law index. Unlike in Type Ia supernovae, calibration of GRB luminosity indicators using a low-redshift sample is difficult. This is because the GRB rate drops rapidly at low redshifts, and some nearby GRBs may be different from their cosmological brethren. Calibrating the standard candles using GRBs in a narrow redshift range (Δz) near a fiducial redshift has been proposed recently. Here we elaborate such a possibility and propose to calibrate {ai} based on the Bayesian theory and to marginalize the c value over a reasonable range of cosmological parameters. We take our newly discovered multivariable GRB luminosity indicator, Eiso=cEa1pta2b, as an example and test the validity of this approach through simulations, where Eiso is the isotropic energy of prompt gamma-rays, Ep is the spectral break energy, and tb is the temporal break time of the optical afterglow light curve. We show that while c strongly depends on the cosmological parameters, neither a1 nor a2 does as long as Δz is small enough. The selection of Δz for a particular GRB sample could be judged according to the size and the observational uncertainty of the sample. There is no preferable redshift to perform the calibration of the indices {ai}, while a lower redshift is preferable for c-marginalization. The best strategy would be to collect GRBs within a narrow redshift bin around a fiducial intermediate redshift (e.g. zc~ 1 or zc~ 2), as the observed GRB redshift distribution is found to peak around this range. Our simulation suggests that with the current observational precisions of measuring Eiso, Ep and tb, 25 GRBs within a redshift bin of Δz~ 0.30 would give fine calibration to the Liang-Zhang luminosity indicator.

  15. Gamma-ray bursts from fast, galactic neutron stars

    SciTech Connect

    Colgate, S.A.; Leonard, P.J.

    1996-04-01

    What makes a Galactic model of gamma-ray bursts (GBs) feasible is the observation of a new population of objects, fast neutron stars, that are isotropic with respect to the galaxy following a finite period, {approx}30 My, after their formation (1). Our Galactic model for the isotropic component of GBs is based upon high-velocity neutron stars (NSs) that have accretion disks. These fast NSs are formed in tidally locked binaries, producing a unique population of high velocity ({approx_gt}10{sup 3} kms{sup -1}) and slowly rotating (8 s) NSs. Tidal locking occurs due to the meridional circulation caused by the conservation of angular momentum of the tidal lobes. Following the collapse to a NS and the explosion, these lobes initially perturb the NS in the direction of the companion. Subsequent accretion (1 to 2 s) occurs on the rear side of the initial motion, resulting in a runaway acceleration of the NS by neutrino emission from the hot accreted matter. The recoil momentum of the relativistic neutrino emission from the localized, down flowing matter far exceeds the momentum drag of the accreted matter. The recoil of the NS is oriented towards the companion, but the NS misses because of the pre-explosion orbital motion. The near miss captures matter from the companion and forms a disk around the NS. Accretion onto the NS from this initially gaseous disk due to the ``alpha`` viscosity results in a soft gamma-ray repeater phase, which lasts {approx}10{sup 4} yr. Later, after the neutron star has moved {approx}30 kpc from its birthplace, solid bodies form in the disk, and accrete to planetoid size bodies after {approx}3{times}10{sup 7} years. Some of these planetoid bodies, with a mass of {approx}10{sup 21}{endash}10{sup 22} g, are perturbed into an orbit inside the tidal distortion radius of {approx_gt}10{sup 5} km. Of these {approx}1% are captured by the magnetic field of the NS at R{lt}2{times}10{sup 3} km to create GBs.

  16. Naked-Eye Gamma-ray Burst Model for GRB 080319B

    NASA Image and Video Library

    Gamma-ray bursts (GRBs) that are longer than two seconds are caused by the detonation of a rapidly rotating massive star at the end of its life. Jets of particles and gamma radiation are emitted in...

  17. In-Orbit Performance of the CALET Gamma-Ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Yamaoka, K.; Calet Collaboration

    2016-10-01

    This poster presentation describes in-orbit operation and performance of the CALET Gamma-ray Burst Monitor (CGBM) which has been operated for about one year since October 2015 on the International Space Station (ISS).

  18. MCRaT Simulations of Long Gamma Ray Burst Spectra and Light Curves

    NASA Astrophysics Data System (ADS)

    Parsotan, T.; Lazzati, D.

    2016-10-01

    We present the results of the Monte Carlo Radiation Transfer, MCRaT, simulations of long gamma ray bursts from a variety of stellar progenitors and jet properties, including variable engines. We also compare the resulting spectra to observed data.

  19. Fireball and Cannonball Models of Gamma-Ray Bursts Confront Observations

    NASA Astrophysics Data System (ADS)

    Dar, Arnon

    2006-12-01

    The two leading contenders for the theory of gamma-ray bursts (GRBs) and their afterglows, the Fireball and Cannonball models, are compared and their predictions are confronted, within space limitations, with key observations, including recent observations with SWIFT.

  20. Monte Carlo models and analysis of galactic disk gamma-ray burst distributions

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon

    1989-01-01

    Gamma-ray bursts are transient astronomical phenomena which have no quiescent counterparts in any region of the electromagnetic spectrum. Although temporal and spectral properties indicate that these events are likely energetic, their unknown spatial distribution complicates astrophysical interpretation. Monte Carlo samples of gamma-ray burst sources are created which belong to Galactic disk populations. Spatial analysis techniques are used to compare these samples to the observed distribution. From this, both quantitative and qualitative conclusions are drawn concerning allowed luminosity and spatial distributions of the actual sample. Although the Burst and Transient Source Experiment (BATSE) experiment on Gamma Ray Observatory (GRO) will significantly improve knowledge of the gamma-ray burst source spatial characteristics within only a few months of launch, the analysis techniques described herein will not be superceded. Rather, they may be used with BATSE results to obtain detailed information about both the luminosity and spatial distributions of the sources.

  1. The Physics of Gamma-Ray Burst Afterglows and the Nature of Their Host Galaxies

    NASA Astrophysics Data System (ADS)

    Vreeswijk, Paul

    Gamma-ray bursts are brief flashes of γ-rays, discovered by the cold-war Vela satellites in the early 1970s. For over two decades the distance scale of these explosions was unknown. In the early 1990s, the Burst and Transient Source experiment onboard the Compton Gamma-Ray Observatory showed gamma-ray bursts to have an isotropic sky distribution, suggestive of a cosmological origin. Thanks to the discovery of X-ray and optical afterglows by BeppoSAX, their distant extra-galactic nature was definitely established in 1997. We discuss the history and current status of the study of gamma-ray burst afterglows, and future VLT observations that can significantly advance the field.

  2. How gravitational-wave observations can shape the gamma-ray burst paradigm

    NASA Astrophysics Data System (ADS)

    Bartos, I.; Brady, P.; Márka, S.

    2013-06-01

    By reaching through shrouding blastwaves, efficiently discovering off-axis events and probing the central engine at work, gravitational wave (GW) observations will soon revolutionize the study of gamma-ray bursts. Already, analyses of GW data targeting gamma-ray bursts have helped constrain the central engines of selected events. Advanced GW detectors with significantly improved sensitivities are under construction. After outlining the GW emission mechanisms from gamma-ray burst progenitors (binary coalescences, stellar core collapses, magnetars and others) that may be detectable with advanced detectors, we review how GWs will improve our understanding of gamma-ray burst central engines, their astrophysical formation channels and the prospects and methods for different search strategies. We place special emphasis on multimessenger searches. To achieve the most scientific benefit, GW, electromagnetic and neutrino observations should be combined to provide greater discriminating power and science reach.

  3. Computational Astrophysics Consortium 3 - Supernovae, Gamma-Ray Bursts and Nucleosynthesis

    SciTech Connect

    Woosley, Stan

    2014-08-29

    Final project report for UCSC's participation in the Computational Astrophysics Consortium - Supernovae, Gamma-Ray Bursts and Nucleosynthesis. As an appendix, the report of the entire Consortium is also appended.

  4. HYPERACCRETING BLACK HOLE AS GAMMA-RAY BURST CENTRAL ENGINE. I. BARYON LOADING IN GAMMA-RAY BURST JETS

    SciTech Connect

    Lei Weihua; Zhang Bing; Liang Enwei E-mail: zhang@physics.unlv.edu

    2013-03-10

    A hyperaccreting stellar-mass black hole has been long speculated as the best candidate for the central engine of gamma-ray bursts (GRBs). Recent rich observations of GRBs by space missions such as Swift and Fermi pose new constraints on GRB central engine models. In this paper, we study the baryon-loading processes of a GRB jet launched from a black hole central engine. We consider a relativistic jet powered by {nu} {nu}-bar -annihilation or by the Blandford-Znajek (BZ) mechanism. We consider baryon loading from a neutrino-driven wind launched from a neutrino-cooling-dominated accretion flow. For a magnetically dominated BZ jet, we consider neutron drifting from the magnetic wall surrounding the jet and subsequent positron capture and proton-neutron inelastic collisions. The minimum baryon loads in both types of jet are calculated. We find that in both cases a more luminous jet tends to be more baryon poor. A neutrino-driven ''fireball'' is typically ''dirtier'' than a magnetically dominated jet, while a magnetically dominated jet can be much cleaner. Both models have the right scaling to interpret the empirical {Gamma}-L{sub iso} relation discovered recently. Since some neutrino-driven jets have too much baryon loading as compared with the data, we suggest that at least a good fraction of GRBs should have a magnetically dominated central engine.

  5. The dark bursts population in a complete sample of bright Swift long gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Melandri, A.; Sbarufatti, B.; D'Avanzo, P.; Salvaterra, R.; Campana, S.; Covino, S.; Vergani, S. D.; Nava, L.; Ghisellini, G.; Ghirlanda, G.; Fugazza, D.; Mangano, V.; Capalbi, M.; Tagliaferri, G.

    2012-04-01

    We study the properties of the population of optically dark events present in a carefully selected complete sample of bright Swift long gamma-ray bursts. The high level of completeness in redshift of our sample (52 objects out of 58) allows us to establish the existence of a genuine dark population, and we are able to estimate the maximum fraction of dark burst events (˜30 per cent) expected for the whole class of long gamma-ray burst. The redshift distribution of this population of dark bursts is similar to that of the whole sample. Interestingly, the rest-frame X-ray luminosity (and the de-absorbed X-ray flux) of the subclass of dark bursts is slightly higher than the average luminosity of the non-dark events. At the same time, the prompt properties do not differ and the optical flux of dark events is at the lower tail of the optical flux distribution, corrected for Galactic absorption. All these properties suggest that dark bursts events generate in much denser environments with respect to normal bright events. We can therefore exclude the high-z and the low-density scenarios and conclude that the major cause of the origin of optically dark events is the dust extinction.

  6. Evidence for cyclotron absorption from spectral features in gamma-ray bursts seen with Ginga

    NASA Technical Reports Server (NTRS)

    Murakami, T.; Fujii, M.; Hayashida, K.; Itoh, M.; Nishimura, J.

    1988-01-01

    New observations by the gamma-ray burst detector on board the Ginga satellite, which has two well-calibrated detectors covering a wide energy range of 1.5 to 375 keV, are reported. The spectral features obtained are consistent with first and second cyclotron harmonics. This finding is taken as strong evidence for the magnetized neutron star model of gamma-ray bursts.

  7. Spectral feature of 31 December 1981 gamma-ray burst not confirmed

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Share, G. H.; Chupp, E. L.; Forrest, D. J.; Matz, S. M.

    1984-01-01

    Measurements of a gamma ray burst at 01:37 UT on December 31, 1981 using the SMM gamma ray spectrometer (GRS) are compared with those made by the Konus instruments on Veneras 11-14. Burst time profiles, photon spectra, and detector energy loss spectra for three time intervals are compared for the GRS and the Konus instruments. It is concluded that the SMM spectra exhibit no evidence for the presence of emission features reported by the Konus group.

  8. Rest-frame properties of 32 gamma-ray bursts observed by the Fermi Gamma-ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Gruber, D.; Greiner, J.; von Kienlin, A.; Rau, A.; Briggs, M. S.; Connaughton, V.; Goldstein, A.; van der Horst, A. J.; Nardini, M.; Bhat, P. N.; Bissaldi, E.; Burgess, J. M.; Chaplin, V. L.; Diehl, R.; Fishman, G. J.; Fitzpatrick, G.; Foley, S.; Gibby, M. H.; Giles, M. M.; Guiriec, S.; Kippen, R. M.; Kouveliotou, C.; Lin, L.; McBreen, S.; Meegan, C. A.; Olivares E., F.; Paciesas, W. S.; Preece, R. D.; Tierney, D.; Wilson-Hodge, C.

    2011-07-01

    Aims: In this paper we study the main spectral and temporal properties of gamma-ray bursts (GRBs) observed by Fermi/GBM. We investigate these key properties of GRBs in the rest-frame of the progenitor and test for possible intra-parameter correlations to better understand the intrinsic nature of these events. Methods: Our sample comprises 32 GRBs with measured redshift that were observed by GBM until August 2010. 28 of them belong to the long-duration population and 4 events were classified as short/hard bursts. For all of these events we derive, where possible, the intrinsic peak energy in the νFν spectrum (Ep,rest), the duration in the rest-frame, defined as the time in which 90% of the burst fluence was observed (T90,rest) and the isotropic equivalent bolometric energy (Eiso). Results: The distribution of Ep,rest has mean and median values of 1.1 MeV and 750 keV, respectively. A log-normal fit to the sample of long bursts peaks at ~800 keV. No high-Ep population is found but the distribution is biased against low Ep values. We find the lowest possible Ep that GBM can recover to be ≈ 15 keV. The T90,rest distribution of long GRBs peaks at ~10 s. The distribution of Eiso has mean and median values of 8.9 × 1052 erg and 8.2 × 1052 erg, respectively. We confirm the tight correlation between Ep,rest and Eiso (Amati relation) and the one between Ep,rest and the 1-s peak luminosity (Lp) (Yonetoku relation). Additionally, we observe a parameter reconstruction effect, i.e. the low-energy power law index α gets softer when Ep is located at the lower end of the detector energy range. Moreover, we do not find any significant cosmic evolution of neither Ep,rest nor T90,rest.

  9. Long gamma-ray bursts and core-collapse supernovae have different environments.

    PubMed

    Fruchter, A S; Levan, A J; Strolger, L; Vreeswijk, P M; Thorsett, S E; Bersier, D; Burud, I; Castro Cerón, J M; Castro-Tirado, A J; Conselice, C; Dahlen, T; Ferguson, H C; Fynbo, J P U; Garnavich, P M; Gibbons, R A; Gorosabel, J; Gull, T R; Hjorth, J; Holland, S T; Kouveliotou, C; Levay, Z; Livio, M; Metzger, M R; Nugent, P E; Petro, L; Pian, E; Rhoads, J E; Riess, A G; Sahu, K C; Smette, A; Tanvir, N R; Wijers, R A M J; Woosley, S E

    2006-05-25

    When massive stars exhaust their fuel, they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. On occasion, this stellar collapse also powers an even more brilliant relativistic explosion known as a long-duration gamma-ray burst. One would then expect that these long gamma-ray bursts and core-collapse supernovae should be found in similar galactic environments. Here we show that this expectation is wrong. We find that the gamma-ray bursts are far more concentrated in the very brightest regions of their host galaxies than are the core-collapse supernovae. Furthermore, the host galaxies of the long gamma-ray bursts are significantly fainter and more irregular than the hosts of the core-collapse supernovae. Together these results suggest that long-duration gamma-ray bursts are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution. Our results directly imply that long gamma-ray bursts are relatively rare in galaxies such as our own Milky Way.

  10. Analyzing Space-Based Interferometric Measurements of Stars and Network Measurements of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Taff, L. G.

    1998-01-01

    Since the announcement of the discovery of sources of bursts of gamma-ray radiation in 1973, hundreds more reports of such bursts have now been published. Numerous artificial satellites have been equipped with gamma-ray detectors including the very successful Compton Gamma Ray Observatory BATSE instrument. Unfortunately, we have made no progress in identifying the source(s) of this high energy radiation. We suspected that this was a consequence of the method used to define gamma-ray burst source "error boxes." An alternative procedure to compute gamma-ray burst source positions, with a purely physical underpinning, was proposed in 1988 by Taff. Since then we have also made significant progress in understanding the analytical nature of the triangulation problem and in computing actual gamma-ray burst positions and their corresponding error boxes. For the former, we can now mathematically illustrate the crucial role of the area occupied by the detectors, while for the latter, the Atteia et al. (1987) catalog has been completely re-reduced. There are very few discrepancies in locations between our results and those of the customary "time difference of arrival" procedure. Thus, we have numerically demonstrated that the end result, for the positions, of these two very different-looking procedures is the same. Finally, for the first time, we provide a sample of realistic "error boxes" whose non-simple shapes vividly portray the difficulty of burst source localization.

  11. On The Prompt Signals of Gamma Ray Bursts

    SciTech Connect

    Chen, Pisin

    2001-09-18

    We introduce a new model of gamma ray burst (GRB) that explains its observed prompt signals, namely, its primary thermal spectrum and high energy tail. This mechanism can be applied to either assumption of GRB progenitor: coalescence of compact objects or hypernova explosion. The key ingredients of our model are: (1) The initial stage of a GRB is in the form of a relativistic quark-gluon plasma ''lava''; (2) The expansion and cooling of this lava results in a QCD phase transition that induces a sudden gravitational stoppage of the condensed non-relativistic baryons and form a hadrosphere; (3) Acoustic shocks and Alfven waves (magnetoquakes) that erupt in episodes from the epicenter efficiently transport the thermal energy to the hadrospheric surface and induce a rapid detachment of leptons and photons from the hadrons; (4) The detached e{sup +}e{sup -} and {gamma} form an opaque, relativistically hot leptosphere, which expands and cools to T {approx} mc{sup 2}, or 0.5 MeV, where e{sup +}e{sup -} {yields} 2{gamma} and its reverse process becomes unbalanced, and the GRB photons are finally released; (5) The ''mode-conversion'' of Alfven waves into electromagnetic waves in the leptosphere provides a ''snowplow'' acceleration that gives rise to the high energy spectrum of GRB. According to this model, the observed GRB photons should have a red-shifted peak frequency at E{sub p} {approx} {Lambda}(1 + {beta}/2)mc{sup 2}/(1 + z), where {Lambda} {approx} {Omicron}(1) is the Lorentz factor of the bulk flow of the lava, which may be determined from the existing GRB data.

  12. Cosmic Evolution of Long Gamma-Ray Burst Luminosity

    NASA Astrophysics Data System (ADS)

    Deng, Can-Min; Wang, Xiang-Gao; Guo, Bei-Bei; Lu, Rui-Jing; Wang, Yuan-Zhu; Wei, Jun-Jie; Wu, Xue-Feng; Liang, En-Wei

    2016-03-01

    The cosmic evolution of gamma-ray burst (GRB) luminosity is essential for revealing the GRB physics and for using GRBs as cosmological probes. We investigate the luminosity evolution of long GRBs with a large sample of 258 Swift/BAT GRBs. By describing the peak luminosity evolution of individual GRBs as {L}{{p}}\\propto \\text{}{(1+z)}k, we get k=1.49+/- 0.19 using the nonparametric τ statistics method without considering observational biases of GRB trigger and redshift measurement. By modeling these biases with the observed peak flux and characterizing the peak luminosity function of long GRBs as a smoothly broken power law with a break that evolves as {L}{{b}}\\propto {(1+z)}{k{{b}}}, we obtain {k}{{b}}={1.14}-0.47+0.99 through simulations based on the assumption that the long GRB rate follows the star formation rate incorporating the cosmic metallicity history. The derived k and kb values are systematically smaller than those reported in previous papers. By removing the observational biases of the GRB trigger and redshift measurement based on our simulation analysis, we generate mock complete samples of 258 and 1000 GRBs to examine how these biases affect the τ statistics method. We get k=0.94+/- 0.14 and k=0.80+/- 0.09 for the two samples, indicating that these observational biases may lead to overestimating the k value. With the large uncertainty of kb derived from our simulation analysis, one cannot even convincingly argue for a robust evolution feature of the GRB luminosity.

  13. REGULATION OF THE SPECTRAL PEAK IN GAMMA-RAY BURSTS

    SciTech Connect

    Beloborodov, Andrei M.

    2013-02-20

    Observations indicate that the peak of a gamma-ray burst spectrum forms in the opaque region of an ultrarelativistic jet. Recent radiative transfer calculations support this picture and show that the spectral peak is inherited from initially thermal radiation, which is changed by heating into a broad photon distribution with a high-energy tail. We discuss the processes that regulate the observed position of the spectral peak E {sub pk}. The opaque jet has three radial zones: (1) the Planck zone r < R {sub P} where a blackbody spectrum is enforced; this zone ends where the Thomson optical depth decreases to {tau} Almost-Equal-To 10{sup 5}, (2) the Wien zone R {sub P} < r < R {sub W} with a Kompaneets parameter y >> 1 where radiation has a Bose-Einstein spectrum, and (3) the Comptonization zone r > R {sub W} where the radiation spectrum develops a high-energy tail. Besides the initial jet temperature, an important factor regulating E {sub pk} is internal dissipation (of bulk motions and magnetic energy) at large distances from the central engine. Dissipation in the Planck zone reduces E {sub pk}, and dissipation in the Wien zone can increase E {sub pk}. In jets with subdominant magnetic fields, the predicted E {sub pk} varies around 1 MeV up to a maximum value of about 10 MeV. If the jet carries an energetically important magnetic field, E {sub pk} can be additionally increased by dissipation of magnetic energy. This increase is suggested by observations, which show E {sub pk} up to about 20 MeV. We also consider magnetically dominated jets; then a simple model of magnetic dissipation gives E {sub pk} Almost-Equal-To 30 {Gamma}{sub W} keV where {Gamma}{sub W} is the jet Lorentz factor at the Wien radius R {sub W}.

  14. A Study of the Gamma-Ray Burst Fundamental Plane

    NASA Astrophysics Data System (ADS)

    Gilbertson, Christian; Dainotti, Maria; Postnikov, Sergey; Nagataki, Shigehiro; Willingale, Richard

    2017-01-01

    A class of long gamma-ray bursts (GRBs) with a plateau phase in their X-ray afterglows obeys a three-dimensional (3D) relation (Dainotti et al. 2016), between the rest-frame time at the end of the plateau, Ta, its corresponding X-ray luminosity, La, and the peak luminosity in the prompt emission, Lpeak. We extended the original analysis with X-ray data from July 2014 to July 2016 achieving a total sample of 183 Swift GRBs with afterglow plateaus and known redshifts. We added the most recent GRBs to the previous ‘gold sample’ (now including 45 GRBs) and obtained a relation plane with intrinsic scatter compatible within one σ with the previous result. We compared several GRB categories, such as short with extended emission, X-ray Flashes, GRBs associated with SNe, long-duration GRBs, and the gold sample, composed only by GRBs with light curves with good data coverage and relatively flat plateaus and evaluated their relation planes. We found that they are not statistically different from the fundamental plane derived from the gold sample and that the fundamental plane still has the smallest scatter. We compared the jet opening angles tabulated in literature with the angles derived using the Eiso-Egamma relation of the method in Pescalli et al. (2015) and calculated the relation plane for a sample of long GRBs accounting for the different jet opening angles. We observed that this correction does not significantly reduce the scatter. In an extended analysis, we found that the fundamental plane is independent from several prompt and afterglow parameters.

  15. Regulation of the Spectral Peak in Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Beloborodov, Andrei M.

    2013-02-01

    Observations indicate that the peak of a gamma-ray burst spectrum forms in the opaque region of an ultrarelativistic jet. Recent radiative transfer calculations support this picture and show that the spectral peak is inherited from initially thermal radiation, which is changed by heating into a broad photon distribution with a high-energy tail. We discuss the processes that regulate the observed position of the spectral peak E pk. The opaque jet has three radial zones: (1) the Planck zone r < R P where a blackbody spectrum is enforced; this zone ends where the Thomson optical depth decreases to τ ≈ 105, (2) the Wien zone R P < r < R W with a Kompaneets parameter y Gt 1 where radiation has a Bose-Einstein spectrum, and (3) the Comptonization zone r > R W where the radiation spectrum develops a high-energy tail. Besides the initial jet temperature, an important factor regulating E pk is internal dissipation (of bulk motions and magnetic energy) at large distances from the central engine. Dissipation in the Planck zone reduces E pk, and dissipation in the Wien zone can increase E pk. In jets with subdominant magnetic fields, the predicted E pk varies around 1 MeV up to a maximum value of about 10 MeV. If the jet carries an energetically important magnetic field, E pk can be additionally increased by dissipation of magnetic energy. This increase is suggested by observations, which show E pk up to about 20 MeV. We also consider magnetically dominated jets; then a simple model of magnetic dissipation gives E pk ≈ 30 ΓW keV where ΓW is the jet Lorentz factor at the Wien radius R W.

  16. Gamma-Ray Bursts from Evolved Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Dokuchaev, V. I.; Eroshenko, Yu. N.; Ozernoy, L. M.

    1998-07-01

    A new cosmological scenario for the origin of gamma-ray bursts (GRBs) is proposed. In our scenario, a highly evolved central core in the dense galactic nucleus is formed, containing a subsystem of compact stellar remnants (CSRs), such as neutron stars and black holes. Those subsystems result from the dynamical evolution of dense central stellar clusters in the galactic nuclei through merging of stars, thereby forming (as has been realized by many authors) the short-lived massive stars and then CSRs. We estimate the rate of random CSR collisions in the evolved galactic nuclei by taking into account, in a procedure similar to that of Quinlan & Shapiro, the dissipative encounters of CSRs, mainly due to radiative losses of gravitational waves, which result in the formation of intermediate short-lived binaries, with further coalescence of the companions to produce GRBs. We also consider how the possible presence of a central supermassive black hole, formed in a highly evolved galactic nucleus, influences the CSR binary formation. This scenario does not postulate ad hoc a required number of tight binary neutron stars in the galaxies. Instead, it gives, for the most realistic parameters of the evolved nuclei, the expected rate of GRBs consistent with the observed one, thereby explaining the GRB appearance as a natural part of the dynamical evolution of galactic nuclei. In addition, this scenario provides an opportunity for a cosmological GRB recurrence, previously considered to be a distinctive feature of GRBs of a local origin only. We also discuss some other observational tests of the proposed scenario.

  17. Gamma-ray burst afterglows from transrelativistic blast wave simulations

    NASA Astrophysics Data System (ADS)

    van Eerten, H. J.; Leventis, K.; Meliani, Z.; Wijers, R. A. M. J.; Keppens, R.

    2010-03-01

    We present a study of the intermediate regime between ultrarelativistic and non-relativistic flow for gamma-ray burst afterglows. The hydrodynamics of spherically symmetric blast waves is numerically calculated using the AMRVAC adaptive mesh refinement code. Spectra and light curves are calculated using a separate radiation code that, for the first time, links a parametrization of the microphysics of shock acceleration, synchrotron self-absorption and electron cooling to a high-performance hydrodynamic simulation. For the dynamics, we find that the transition to the non-relativistic regime generally occurs later than expected, the Sedov-Taylor solution overpredicts the late-time blast wave radius and the analytical formula for the blast wave velocity from Huang, Dai & Lu overpredicts the late-time velocity by a factor of 4/3. Also, we find that the lab frame density directly behind the shock front divided by the fluid Lorentz factor squared remains very close to four times the unshocked density, while the effective adiabatic index of the shock changes from relativistic to non-relativistic. For the radiation, we find that the flux may differ up to an order of magnitude depending on the equation of state that is used for the fluid and that the counterjet leads to a clear rebrightening at late times for hard-edged jets. Simulating GRB 030329 using predictions for its physical parameters from the literature leads to spectra and light curves that may differ significantly from the actual data, emphasizing the need for very accurate modelling. Predicted light curves at low radio frequencies for a hard-edged jet model of GRB 030329 with opening angle 22° show typically two distinct peaks, due to the combined effect of jet break, non-relativistic break and counterjet. Spatially resolved afterglow images show a ring-like structure.

  18. Towards a complete theory of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Dar, Arnon; de Rújula, A.

    2004-12-01

    Gamma ray bursts (GRBs) are notorious for their diversity. Yet, they have a series of common features. The typical energy of their γ-rays is a fraction of an MeV. The energy distributions are well described by a “Band spectrum”, with “peak energies” spanning a surprisingly narrow range. The time structure of a GRB consists of pulses, superimposed or not, rising and decreasing fast. The number of photons in a pulse, the pulses’ widths and their total energy vary within broad but specific ranges. Within a pulse, the energy spectrum softens with increasing time. The duration of a pulse decreases at higher energies and its peak intensity shifts to earlier time. Many other correlations between pairs of GRB observables have been identified. Last (and based on one measured event!) the γ-ray polarization may be very large. A satisfactory theory of GRBs should naturally and very simply explain, among others, all these facts. We show that the “cannonball” (CB) model does it. In the CB model the process leading to the ejection of highly relativistic jetted CBs in core-collapse supernova (SN) explosions is akin to the one observed in quasars and microquasars. The prompt γ-ray emission—the GRB—is explained extremely well by inverse Compton scattering of light in the near environment of the SN by the electrons in the CBs’ plasma. We have previously shown that the CB-model's description of GRB afterglows as synchrotron radiation from ambient electrons—swept in and accelerated within the CBs—is also simple, universal and very successful. The only obstacle still separating the CB model from a complete theory of GRBs is the theoretical understanding of the CBs’ ejection mechanism in SN explosions.

  19. Compact Binary Progenitors of Short Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Giacomazzo, Bruno; Perna, Rosalba; Rezzolla, Luciano; Troja, Eleonora; Lazzati, Davide

    2013-01-01

    In recent years, detailed observations and accurate numerical simulations have provided support to the idea that mergers of compact binaries containing either two neutron stars (NSs) or an NS and a black hole (BH) may constitute the central engine of short gamma-ray bursts (SGRBs). The merger of such compact binaries is expected to lead to the production of a spinning BH surrounded by an accreting torus. Several mechanisms can extract energy from this system and power the SGRBs. Here we connect observations and numerical simulations of compact binary mergers, and use the current sample of SGRBs with measured energies to constrain the mass of their powering tori. By comparing the masses of the tori with the results of fully general-relativistic simulations, we are able to infer the properties of the binary progenitors that yield SGRBs. By assuming a constant efficiency in converting torus mass into jet energy epsilon(sub jet) = 10%, we find that most of the tori have masses smaller than 0.01 Solar M, favoring "high-mass" binary NSs mergers, i.e., binaries with total masses approx >1.5 the maximum mass of an isolated NS. This has important consequences for the gravitational wave signals that may be detected in association with SGRBs, since "high-mass" systems do not form a long-lived hypermassive NS after the merger. While NS-BH systems cannot be excluded to be the engine of at least some of the SGRBs, the BH would need to have an initial spin of approx. 0.9 or higher.

  20. A unifying view of gamma-ray burst afterglows

    NASA Astrophysics Data System (ADS)

    Ghisellini, G.; Nardini, M.; Ghirlanda, G.; Celotti, A.

    2009-02-01

    We selected a sample of 33 gamma-ray bursts detected by Swift, with known redshift and optical extinction at the host frame. For these, we constructed the de-absorbed and K-corrected X-ray and optical rest-frame light curves. These are modelled as the sum of two components: emission from the forward shock due to the interaction of a fireball with the circumburst medium and an additional component, treated in a completely phenomenological way. The latter can be identified, among other possibilities, as a `late prompt' emission produced by a long-lived central engine with mechanisms similar to those responsible for the production of the `standard' early prompt radiation. Apart from flares or re-brightenings, that we do not model, we find a good agreement with the data, despite of their complexity and diversity. Although based, in part, on a phenomenological model with a relatively large number of free parameters, we believe that our findings are a first step towards the construction of a more physical scenario. Our approach allows us to interpret the behaviour of the optical and X-ray afterglows in a coherent way, by a relatively simple scenario. Within this context, it is possible to explain why sometimes no jet break is observed; why, even if a jet break is observed, it is often chromatic and why the steepening after the jet break time is often shallower than predicted. Finally, the decay slope of the late prompt emission after the shallow phase is found to be remarkably similar to the time profile expected by the accretion rate of fall-back material (i.e. ~ t-5/3), suggesting that this can be the reason why the central engine can be active for a long time.

  1. Universal Scaling Law in Long Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Tsutsui, Ryo; Shigeyama, Toshikazu

    2013-06-01

    The overwhelming diversity of long gamma-ray bursts (LGRBs), discovered after the launch of the Swift satellite,is a major obstacle to LGRB studies. Recently, it was shown that the prompt emission of LGRBs can be classified into three subclasses: Type I and Type II LGRBs, populating separate fundamental planes in a 3D space defined by the peak luminosity, the duration, and the spectral peak energy, and outliers belonging to none of these planes. Here, we show that Type I LGRBs exhibit different shapes of light curves from that of Type II LGRBs. Furthermore, we demonstrate that this classification has uncovered a new scaling law concerning the light curve of Type II LGRBs, over a span of 8 orders of magnitude ranging from the prompt emission to the late X-ray afterglow one. The scaled light curve has four distinct phases. The first phase has a characteristic time-scale, while the three subsequent phases exhibit power-law behaviors with different exponents. We attempt a new interpretation in terms of the emission from an optically thick fireball propagating in the cricumstellar matter at relativistic speed, and argue that the four observed phases correspond to its hydrodynamical phases. Our classification scheme succeeds in pinning down intrinsic luminosities of Type II LGRBs through the scaling law with a sample of polymorphic GRBs. Further refinements of this scheme and scaling law will make it possible to use a subclass of LGRBs as new standard candles with the same reliability and accuracy as Type Ia supernovae in more distant universe than the light from supernovae can reach.

  2. Gamma-ray burst engines may have no memory

    NASA Astrophysics Data System (ADS)

    Baldeschi, A.; Guidorzi, C.

    2015-01-01

    Context. A sizeable fraction of gamma-ray burst (GRB) time profiles consist of a temporal sequence of pulses. The nature of this stochastic process carries information on how GRB inner engines work. The so-called interpulse time defines the interval between adjacent pulses, excluding the long quiescence periods during which the signal drops to the background level. It was found by many authors in the past that interpulse times are lognormally distributed, at variance with the exponential case that is expected for a memoryless process. Aims: We investigated whether the simple hypothesis of a temporally uncorrelated sequence of pulses is really to be rejected, as a lognormal distribution necessarily implies. Methods: We selected and analysed a number of multi-peaked CGRO/BATSE GRBs and simulated similar time profiles, with the crucial difference that we assumed exponentially distributed interpulse times, as is expected for a memoryless stationary Poisson process. We then identified peaks in both data sets using a novel peak search algorithm, which is more efficient than others used in the past. Results: We independently confirmed that the observed interpulse time distribution is approximately lognormal. However, we found the same results on the simulated profiles, in spite of the intrinsic exponential distribution. Although intrinsic lognormality cannot be ruled out, this shows that intrinsic interpulse time distribution in real data could still be exponential, while the observed lognormal could be ascribed to the low efficiency of peak search algorithms at short values combined with the limitations of a bin-integrated profile. Conclusions: Our result suggests that GRB engines may emit pulses after the fashion of nuclear radioactive decay, that is, as a memoryless process.

  3. Nuclear composition of magnetized gamma-ray burst jets

    NASA Astrophysics Data System (ADS)

    Shibata, Sanshiro; Tominaga, Nozomu

    2015-06-01

    We investigate the fraction of metal nuclei in the relativistic jets of gamma-ray bursts associated with core-collapse supernovae. We simulate the fallback in jet-induced explosions with two-dimensional relativistic hydrodynamics calculations and the jet acceleration with steady, radial, relativistic magnetohydrodynamics calculations, and derive the detailed nuclear composition of the jet by post-processing calculation. We found that if the temperature at the jet launch site is above 4.7 × 109 K, quasi-statistical equilibrium is established and heavy nuclei are dissociated into light particles such as 4He during the acceleration of the jets. The criterion for the survival of metal nuclei is written in terms of the isotropic jet luminosity as L_j^iso ≲ 3.9 × 10^{50} ( R_i/107 cm)^2(1 + σi) erg s-1, where Ri and σi are the initial radius of the jets and the initial magnetization parameter, respectively. If the jet is initially dominated by radiation field (i.e., σi ≪ 1) and the isotropic luminosity is relatively high (L_j^iso ≳ 4 × 10^{52} erg s-1), the metal nuclei cannot survive in the jet. On the other hand, if the jet is mainly accelerated by magnetic field (i.e., σi ≫ 1), metal nuclei initially contained in the jet can survive without serious dissociation even in the case of a high-luminosity jet. If the jet contains metal nuclei, the dominant nuclei are 28Si, 16O, and 32S and the mean mass number can be ˜ 25.

  4. Generation of circular polarization of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Batebi, S.; Mohammadi, R.; Ruffini, R.; Tizchang, S.; Xue, S.-S.

    2016-09-01

    The generation of the circular polarization of gamma ray burst (GRB) photons is discussed in this paper via their interactions with astroparticles in the presence or absence of background fields such as magnetic fields and noncommutative space-time geometry. Solving the quantum Boltzmann equation for GRB photons as a photon ensemble, we discuss the generation of circular polarization (as Faraday conversion phase shift Δ ϕFC) of GRBs in the following cases: (i) intermediate interactions, i.e., the Compton scattering of GRBs in the galaxy cluster magnetic field and in the presence of noncommutative space-time geometry, as well as the scattering of GRBs in the cosmic neutrino background (CNB) and cosmic microwave background (CMB); (ii) interactions with particles and fields in shockwaves, i.e., the Compton scattering of GRBs with accelerated charged particles in the presence of magnetic fields. We found that (i) after shockwave crossing, the greatest contribution of Δ ϕFC for energetic GRBs (of the order of GeV and larger) comes from GRB-CMB interactions, but for low-energy GRBs the contributions of the Compton scattering of GRBs in the galaxy cluster magnetic field dominate; (ii) in shockwave crossing, the magnetic field has significant effects on converting a GRB's linear polarization to a circular one, and this effect can be used to better understand the magnetic profile in shockwaves. The main aim of this work is to study and measure the circular polarization of GRBs for a better understanding of the physics and mechanism of the generation of GRBs and their interactions before reaching us.

  5. Cosmological blueshifting may explain the gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Krasiński, Andrzej

    2016-02-01

    It is shown that the basic observed properties of the gamma-ray bursts (GRBs) are accounted for if one assumes that the GRBs arise by blueshifting the emission radiation of hydrogen and helium generated during the last scattering epoch. The blueshift generator for a single GRB is a region with a nonconstant bang-time function tB(r ) (described by a Lemaître-Tolman (L-T) exact solution of Einstein's equations) matched into a homogeneous and isotropic (Friedmann) background. Blueshift visible to the present observer arises only on those rays that are emitted radially in an L-T region. The paper presents three L-T models with different Big Bang profiles, adapted for the highest and the lowest end of the GRB frequency range. The models account for (1) the observed frequency range of the GRBs; (2) their limited duration; (3) the afterglows; (4) their hypothetical collimation into narrow jets; (5) the large distances to their sources; (6) the multitude of the observed GRBs. Properties (2), (3) and (6) are accounted for only qualitatively. With a small correction of the parameters of the model, the implied perturbations of the CMB radiation will be consistent with those actually caused by the GRBs. A complete model of the Universe would consist of many L-T regions with different tB(r ) profiles, matched into the same Friedmann background. This paper is meant to be an initial exploration of the possibilities offered by models of this kind; the actual fitting of all parameters to observational results requires fine-tuning of several interconnected variables and is left for a separate study.

  6. The Second Swift BAT Gamma-Ray Burst Catalog

    NASA Technical Reports Server (NTRS)

    Barthelmy, S. D.; Baumgartner, W. H.; Cummings, J. R.; Fenimore, E. E.; Gehrels, N.; Krimm, H. A.; Markwardt, C. B.; Palmer, D. M.; Parsons, A. M.; Sato, G.; hide

    2010-01-01

    We present the second Swift Burst Alert Telescope (BAT) catalog of gamma-ray bursts (GRBs), which contains 476 bursts detected by the BAT between 2004 December 19 and 2009 December 21. This catalog (hereafter the BAT2 catalog) presents burst trigger time, location, 90% error radius, duration, fluence, peak flux, time-averaged spectral parameters and time-resolved spectral parametert:; measured by the BAT. In the correlation study of various observed parameters extracted from the BAT prompt emission data, we distinguish among long-duration GRBs (L-GRBs), short-duration GRBs (S-GRBs), and short-duration GRBs with extended emission (S-GRBs with E.E.) to investigate differences in the prompt emission properties. The fraction of L-GRBs, S-GRBs and S-GRBs with E.E. in the catalog are 89%, 8% and 2% respectively. We compare the BAT prompt emission properties with the BATSE, BeppoSAX and HETE-2 GRB samples. We also correlate the observed prompt emission properties with the redshifts for the GRBs with known redshift. The BAT T90 and T50 durations peak at 70 s and 30 s, respectively. We confirm that the spectra of the BAT S-GRBs are generally harder than those of the L-GRBs. The time-averaged spectra of the BAT S GRBs with E.E. are similar to those of the L-GRBs. Whereas, the spectra of the initial short spikes of the S-GRBs with E.E. are similar to those of the S-GRBs. We show that the BAT GRB samples are significantly softer than the BATSE bright GRBs, and that the time-averaged E obs/peak of the BAT GRBs peaks at 80 keV which is significantly lower energy than those of the BATSE sample which peak at 320 keV. The time-averaged spectral properties of the BAT GRB sample are similar to those of the HETE-2 GRB samples. By time-resolved spectral analysis, we find that 10% of the BAT observed photon indices are outside the allowed region of the synchrotron shock model. The observed durations of the BAT high redshift GRBs are not systematically longer than those of the moderate

  7. The Ulysses Supplement to the BATSE 3B Catalog of Cosmic Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Hurley, K.

    1998-01-01

    We present Interplanetary Network Localization information for 219 gamma-ray burst of the 3rd BATSE catalog, obtained by analyzing the arrival times of these bursts at the Ulysses and Compton Gamma Ray Observatory (CGRO) spacecraft. For any given burst observed by these two spacecraft, arrival time analysis (triangulation) results in an annulus of possible arrival directions whose width varies between 7 arcseconds and 32 arcminutes, depending on the intensity and time history of the burst, and the distance of the Ulysses spacecraft from Earth. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the error box area by a factor of 30.

  8. Gamma-ray burst results from DMSP satellites. [Defense Meteorological Satellite Program (DMSP)

    SciTech Connect

    Terrell, J.; Lee, P.; Klebesadel, R.W. ); Griffee, J.W. )

    1992-01-01

    Gamma-ray burst detectors are aboard three US Air Force Defense Meteorological Satellite Program (DMSP) spacecraft, in orbit at 800 km altitude. A large number of bursts have been detected by DMSP, often confirming and supplementing data from GRO and other spacecraft, sometimes detecting bursts not otherwise known. The position of an unknown source may be considerably restricted by knowledge of the several DMSP spacecraft locations and fields of view. These data may be of considerable assistance in understanding the gamma-ray burst phenomenon.

  9. Swift and Fermi observations of the early afterglow of the short gamma-ray burst 090510

    SciTech Connect

    De Pasquale, M.

    2010-01-14

    Here, we present the observations of GRB090510 performed by the Fermi Gamma-Ray Space Telescope and the Swift observatory. In a GeV range, we detected a bright, short burst that shows an extended emission. Furthermore, its optical emission initially rises, a feature so far observed only in long bursts, while the X-ray flux shows an initial shallow decrease, followed by a steeper decay. This exceptional behavior enables us to investigate the physical properties of the gamma-ray burst outflow, poorly known in short bursts. Here, we discuss internal and external shock models for the broadband energy emission of this object.

  10. A search for optical counterparts of gamma-ray bursts. Final report

    SciTech Connect

    Park, Hye-Sook

    1995-03-09

    Gamma Ray Bursts (GRBS) are mysterious flashes of gamma rays lasting several tens to hundreds of seconds that occur approximately once per day. NASA launched the orbiting Compton Gamma Ray Observatory to study GRBs and other gamma ray phenomena. CGRO carries the Burst and Transient Experiment (BATSE) specifically to study GRBS. Although BATSE has collected data on over 600 GRBS, and confirmed that GRBs are localized, high intensity point sources of MeV gamma rays distributed isotropically in the sky, the nature and origin of GRBs remains a fundamental problem in astrophysics. BATSE`s 8 gamma ray sensors located on the comers of the box shaped CGRO can detect the onset of GRBs and record their intensity and energy spectra as a function of time. The position of the burst on the sky can be determined to < {plus_minus}10{degrees} from the BATSE data stream. This position resolution is not sufficient to point a large, optical telescope at the exact position of a GRB which would determine its origin by associating it with a star. Because of their brief duration it is not known if GRBs are accompanied by visible radiation. Their seemingly large energy output suggests thatthis should be. Simply scaling the ratio of visible to gamma ray intensities of the Crab Nebula to the GRB output suggests that GRBs ought to be accompanied by visible flashes of magnitude 10 or so. A few photographs of areas containing a burst location that were coincidentally taken during the burst yield lower limits on visible output of magnitude 4. The detection of visible light during the GRB would provide information on burst physics, provide improved pointing coordinates for precise examination of the field by large telescope and provide the justification for larger dedicated optical counterpart instruments. The purpose of this experiment is to detect or set lower limits on optical counterpart radiation simultaneously accompanying the gamma rays from

  11. The Identification of Two Different Spectral Types of Pulses in Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Pendleton, G. N.; Paciesas, W. S.; Briggs, M. S.; Preece, R. D.; Mallozzi, R. S.; Meegan, C. A.; Horack, J. M.; Fishman, G. J.; Band, D. L.; Matteson, J. L.; Skelton, R. T.; Hakkila, J.; Ford, L. A.; Kouveliotou, C.; Koshut, T. M.

    1997-01-01

    It is shown in this study that two different types of spectral emission are generally produced in gamma-ray bursts. A subset of bursts is identified that exhibits a marked lack of fluence above 300 keV, and these bursts are shown to have luminosities about an order of magnitude lower than bursts with significant fluence above 300 keV. The bursts lacking emission above 300 keV exhibit an effectively homogeneous intensity distribution. In addition, it is shown that both types of emission are common in many bursts, demonstrating that a single source object is capable of generating both of them. These results strongly favor a gamma-ray burst source object that produces two different types of emission with varying degrees of superposition. The impact of this behavior is strong enough that it affects the properties of the burst intensity distribution, as well as the burst spectral characteristics.

  12. Method of separation of celestial gamma-ray bursts from solar flares

    NASA Technical Reports Server (NTRS)

    Chuang, K. W.; White, R. S.; Klebesadel, R. W.; Laros, J. G.

    1992-01-01

    We recently discovered 217 'new' celestial gamma-ray burst candidates from the 'new' burst search of the PVO real time data base. The burst search covered the time period from September 1978 to July 1988. Sixty were confirmed by at least one other spacecraft, e.g., ISEE-3, V-II, V-12, etc. None triggered the PVO high time resolution memory. In this paper we describe a new algorithm based on the relationship between time width T(w) and hardness ratio HR, to distinguish cosmic gamma-ray bursts from solar flares without knowing the directions of the events. The algorithm was tested with 83 triggered and 60 nontriggered confirmed gamma-ray bursts and 30 confirmed solar flares from PVO.

  13. Terrestrial Gamma-ray Flashes (TGFs) Observed with the Fermi-Gamma-ray Burst Monitor: Temporal and Spectral Properties

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Briggs, M. S.; Connaughton, W.; Wilson-Hodge, C.; Bhat, P. N.

    2010-01-01

    The Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope Observatory (Fermi) was detecting 2.1 TGFs per week. This rate has increased by a factor of 8 since new flight software was uploaded to the spacecraft in November 2009 in order to increase the sensitivity of GBM to TGFs. Further upgrades to Fermi-GBM to allow observations of weaker TGFs are in progress. The high time resolution (2 s) allows temporal features to be resolved so that some insight may be gained on the origin and transport of the gamma-ray photons through the atmosphere. The absolute time of the TGFs, known to several microseconds, also allows accurate correlations of TGFs with lightning networks and other lightning-related phenomena. The thick bismuth germanate (BGO) scintillation detectors of the GBM system have observed photon energies from TGFs at energies above 40 MeV. New results on the some temporal aspects of TGFs will be presented along with spectral characteristics and properties of several electron-positron TGF events that have been identified.

  14. Terrestrial Gamma-Ray Flashes (TGFs) Observed with the Fermi-Gamma-Ray Burst Monitor: The First Hundred TGFs

    NASA Technical Reports Server (NTRS)

    Fishman, G J.; Briggs, M. S.; Connaughton, V.; Bhat, P. N.

    2010-01-01

    The Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope Observatory (Fermi) is now detecting 2.1 TGFs per week. At this rate, nearly a hundred TGFs will have been detected by the time of this Meeting. This rate has increased by a factor of 8 since new flight software was uploaded to the spacecraft in November 2009 in order to increase the sensitivity of GBM to TGFs. The high time resolution (2 microseconds) allows temporal features to be resolved so that some insight may be gained on the origin and transport of the gamma-ray photons through the atmosphere. The absolute time of the TGFs, known to several microseconds, also allows accurate correlations of TGFs with lightning networks and other lightning-related phenomena. The thick bismuth germanate (BGO) scintillation detectors of the GBM system have observed photon energies from TGFs at energies above 40 MeV. New results on the some temporal aspects of TGFs will be presented.

  15. Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Mars Observer, Compton Gamma Ray Observatory and Ulysses

    NASA Technical Reports Server (NTRS)

    Laros, J. G.; Boynton, W. V.; Hurley, K.; Kouveliotou, C.; McCollough, M. L.; Fishman, G. J.; Meegan, C. A.

    1997-01-01

    Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to approximately 2 deg accuracy by the CGRO Burst and Transient Source Experiment (BATSE). We computed arrival-time error boxes with larger dimensions ranging from a few arcminutes to the diameters of the BATSE-only boxes and with smaller dimensions in the arcminute range. Three events are of particular interest: GB 930704 (BATSE 2428) has been described as a possible repeater. The arrival-time information is consistent with that hypothesis, but only just so. The GB 930706 (2431) box, at approximately 1 min x 4 min, is the only one this small obtained since Pioneer Venus Orbiter (PVO) entered the Venusian atmosphere in 1992 October. Sensitive radio and optical observations of this location were made within 8 and 9 days of the burst, but no counterpart candidates were identified. GB 930801 (2477) is the first GRB that had its localization improved by taking into account BATSE Earth occultation.

  16. REVISITING THE LIGHT CURVES OF GAMMA-RAY BURSTS IN THE RELATIVISTIC TURBULENCE MODEL

    SciTech Connect

    Lin, Da-Bin; Gu, Wei-Min; Hou, Shu-Jin; Liu, Tong; Sun, Mou-Yuan; Lu, Ju-Fu E-mail: lujf@xmu.edu.cn

    2013-10-10

    Rapid temporal variability has been widely observed in the light curves of gamma-ray bursts (GRBs). One possible mechanism for such variability is related to the relativistic eddies in the jet. In this paper, we include the contribution of the inter-eddy medium together with the eddies to the gamma-ray emission. We show that the gamma-ray emission can either lead or lag behind the observed synchrotron emission, where the latter originates in the inter-eddy medium and provides most of the seed photons for producing gamma-ray emission through inverse Compton scattering. As a consequence, we argue that the lead/lag found in non-stationary short-lived light curves may not reveal the intrinsic lead/lag of different emission components. In addition, our results may explain the lead of gamma-ray emission with respect to optical emission observed in GRB 080319B.

  17. A Study of the Gamma-Ray Burst Fundamental Plane

    NASA Astrophysics Data System (ADS)

    Dainotti, Maria; Gilbertson, Christian; Postnikov, Sergey; Nagataki, Shigehiro; Willingale, Richard

    2017-01-01

    A class of long gamma-ray bursts (GRBs) with a plateau phase in their X-ray afterglows obeys a three dimensional (3D) relation (Dainotti et al. 2016), between the rest-frame time at the end of the plateau, $T_a$, its corresponding X-ray luminosity, $L_{a}$, and the peak luminosity in the prompt emission, $L_{peak}$, which is an extension of the two dimensional Dainotti relation. This 3D relation identifies a GRB fundamental plane whose existence we confirmed. We extended the original analysis with X-ray data from July 2014 to July 2016 achieving a total sample of 183 {\\it Swift} GRBs with afterglow plateaus and known redshifts. We added the most recent GRBs to the previous `gold sample' (now including 45 GRBs) and obtained an intrinsic scatter compatible within one $\\sigma$ with the previous result. We compared several GRB categories, such as short with extended emission, X-ray Flashes, GRBs associated with SNe, a sample of only long duration GRBs (132), selected from the total sample by excluding GRBs of the previous categories, and the gold sample, composed only by GRBs with light curves with good data coverage and relatively flat plateaus. We evaluated the relation planes for each of the mentioned categories and showed that they are not statistically different from the plane derived from the gold sample and that the fundamental plane derived from the gold sample has an intrinsic scatter smaller than any plane derived from the other sample categories. We compared the jet opening angles tabulated in literature with the angles derived using the $E_{iso}-E_{gamma}$ relation of the method in Pescalli et al. (2015) and calculated the relation plane for a sample of long GRBs accounting for the different jet opening angles. We observed that this correction does not significantly reduce the scatter. In an extended analysis, we found that the fundamental plane is independent from several prompt and afterglow parameters, such as the jet opening angle, $\\theta

  18. The protomagnetar model for gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Metzger, B. D.; Giannios, D.; Thompson, T. A.; Bucciantini, N.; Quataert, E.

    2011-05-01

    Long duration gamma-ray bursts (GRBs) originate from the core collapse of massive stars, but the identity of the central engine remains elusive. Previous work has shown that rapidly spinning, strongly magnetized protoneutron stars ('millisecond protomagnetars') produce outflows with energies, time-scales and magnetizations σ0 (maximum Lorentz factor) that are consistent with those required to produce long duration GRBs. Here we extend this work in order to construct a self-consistent model that directly connects the properties of the central engine to the observed prompt emission. Just after the launch of the supernova shock, a wind heated by neutrinos is driven from the protomagnetar. The outflow is collimated into a bipolar jet by its interaction with the progenitor star. As the magnetar cools, the wind becomes ultrarelativistic and Poynting flux dominated (σ0≫ 1) on a time-scale comparable to that required for the jet to clear a cavity through the star. Although the site and mechanism of the prompt emission are debated, we calculate the emission predicted by two models: magnetic dissipation and shocks. Magnetic reconnection may occur near the photosphere if the outflow develops an alternating field structure due to e.g. magnetic instabilities or a misalignment between the magnetic and rotation axes. Shocks may occur at larger radii because the Lorentz factor of the wind increases with time, such that the faster jet at late times collides with slower material released earlier. Our results favour magnetic dissipation as the prompt emission mechanism, in part because it predicts a relatively constant 'Band' spectral peak energy Epeak with time during the GRB. The baryon loading of the jet decreases abruptly when the neutron star becomes transparent to neutrinos at ? s. Jets with ultrahigh magnetization cannot effectively accelerate and dissipate their energy, which suggests this transition ends the prompt emission. This correspondence may explain both the

  19. Gamma-ray bursts, QSOs and active galaxies.

    PubMed

    Burbidge, Geoffrey

    2007-05-15

    The similarity of the absorption spectra of gamma-ray burst (GRB) sources or afterglows with the absorption spectra of quasars (QSOs) suggests that QSOs and GRB sources are very closely related. Since most people believe that the redshifts of QSOs are of cosmological origin, it is natural to assume that GRBs or their afterglows also have cosmological redshifts. For some years a few of us have argued that there is much optical evidence suggesting a very different model for QSOs, in which their redshifts have a non-cosmological origin, and are ejected from low-redshift active galaxies. In this paper I extend these ideas to GRBs. In 2003, Burbidge (Burbidge 2003 Astrophys. J. 183, 112-120) showed that the redshift periodicity in the spectra of QSOs appears in the redshift of GRBs. This in turn means that both the QSOs and the GRB sources are similar objects ejected from comparatively low-redshift active galaxies. It is now clear that many of the GRBs of low redshift do appear in, or very near, active galaxies.A new and powerful result supporting this hypothesis has been produced by Prochter et al. (Prochter et al. 2006 Astrophys. J. Lett. 648, L93-L96). They show that in a survey for strong MgII absorption systems along the sightlines to long-duration GRBs, nearly every sightline shows at least one absorber. If the absorbers are intervening clouds or galaxies, only a small fraction should show absorption of this kind. The number found by Prochter et al. is four times higher than that normally found for the MgII absorption spectra of QSOs. They believe that this result is inconsistent with the intervening hypothesis and would require a statistical fluctuation greater than 99.1% probability. This is what we expect if the absorption is intrinsic to the GRBs and the redshifts are not associated with their distances. In this case, the absorption must be associated with gas ejected from the QSO. This in turn implies that the GRBs actually originate in comparatively low

  20. DO THE FERMI GAMMA-RAY BURST MONITOR AND SWIFT BURST ALERT TELESCOPE SEE THE SAME SHORT GAMMA-RAY BURSTS?

    SciTech Connect

    Burns, Eric; Briggs, Michael S.; Connaughton, Valerie; Zhang, Bin-Bin; Lien, Amy; Goldstein, Adam; Troja, Eleonora

    2016-02-20

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors.

  1. Do the Fermi Gamma-Ray Burst Monitor and Swift Burst Alert Telescope see the Same Short Gamma-Ray Bursts?

    NASA Astrophysics Data System (ADS)

    Burns, Eric; Connaughton, Valerie; Zhang, Bin-Bin; Lien, Amy; Briggs, Michael S.; Goldstein, Adam; Pelassa, Veronique; Troja, Eleonora

    2016-02-01

    Compact binary system mergers are expected to generate gravitational radiation detectable by ground-based interferometers. A subset of these, the merger of a neutron star with another neutron star or a black hole, are also the most popular model for the production of short gamma-ray bursts (GRBs). The Swift Burst Alert Telescope (BAT) and the Fermi Gamma-ray Burst Monitor (GBM) trigger on short GRBs (SGRBs) at rates that reflect their relative sky exposures, with the BAT detecting 10 per year compared to about 45 for GBM. We examine the SGRB populations detected by Swift BAT and Fermi GBM. We find that the Swift BAT triggers on weaker SGRBs than Fermi GBM, providing they occur close to the center of the BAT field of view, and that the Fermi GBM SGRB detection threshold remains flatter across its field of view. Overall, these effects combine to give the instruments the same average sensitivity, and account for the SGRBs that trigger one instrument but not the other. We do not find any evidence that the BAT and GBM are detecting significantly different populations of SGRBs. Both instruments can detect untriggered SGRBs using ground searches seeded with time and position. The detection of SGRBs below the on-board triggering sensitivities of Swift BAT and Fermi GBM increases the possibility of detecting and localizing the electromagnetic counterparts of gravitational wave (GW) events seen by the new generation of GW detectors.

  2. Fermi/GAMMA-RAY BURST MONITOR OBSERVATIONS OF SGR J0501+4516 BURSTS

    SciTech Connect

    Lin Lin; Zhang Shuangnan; Kouveliotou, Chryssa; Van der Horst, Alexander J.; Finger, Mark H.; Guiriec, Sylvain; Preece, Robert; Chaplin, Vandiver; Bhat, Narayan; Woods, Peter M.; Goegues, Ersin; Kaneko, Yuki; Scargle, Jeffrey; Von Kienlin, Andreas; Watts, Anna L.; Wijers, Ralph A. M. J.; Gehrels, Neil; Harding, Alice

    2011-10-01

    We present our temporal and spectral analyses of 29 bursts from SGR J0501+4516, detected with the gamma-ray burst monitor on board the Fermi Gamma-ray Space Telescope during 13 days of the source's activation in 2008 (August 22- September 3). We find that the T{sub 90} durations of the bursts can be fit with a log-normal distribution with a mean value of {approx}123 ms. We also estimate for the first time event durations of soft gamma repeater (SGR) bursts in photon space (i.e., using their deconvolved spectra) and find that these are very similar to the T{sub 90} values estimated in count space (following a log-normal distribution with a mean value of {approx}124 ms). We fit the time-integrated spectra for each burst and the time-resolved spectra of the five brightest bursts with several models. We find that a single power law with an exponential cutoff model fits all 29 bursts well, while 18 of the events can also be fit with two blackbody functions. We expand on the physical interpretation of these two models and we compare their parameters and discuss their evolution. We show that the time-integrated and time-resolved spectra reveal that E{sub peak} decreases with energy flux (and fluence) to a minimum of {approx}30 keV at F = 8.7 x 10{sup -6} erg cm{sup -2} s{sup -1}, increasing steadily afterward. Two more sources exhibit a similar trend: SGRs J1550-5418 and 1806-20. The isotropic luminosity, L{sub iso}, corresponding to these flux values is roughly similar for all sources (0.4-1.5 x 10{sup 40} erg s{sup -1}).

  3. Long gamma-ray bursts and core-collapse supernovae have differentenvironments

    SciTech Connect

    Fruchter, A.S.; Levan, A.J.; Strolger, L.; Vreeswijk, P.M.; Thorsett, S.E.; Bersier, D.; Burud, I.; Castro Ceren, J.M.; Castro-Tirado, A.J.; Conselice, C.; Dahlen, T.; Ferguson, H.C.; Fynbo,J.P.U.; Garnavich, P.M.; Gibbons, R.A.; Gorosabel, J.; Gull, T.R.; Hjorth, J.; Holland, S.T.; Kouveliotou, C.; Levay, Z.; Livio, M.; Metzger, M.R.; Nugent, P.E.; Petro, L.; Pian, E.; Rhoads, J.E.; Riess,A.G.; Sahu, K.C.; Smette, A.; Tanvir, N.R.; Wijers, R.A.M.J.; Woosley, S.E.

    2006-05-01

    When massive stars exhaust their fuel they collapse andoften produce the extraordinarily bright explosions known ascore-collapse supernovae. On occasion, this stellar collapse also powersan even more brilliant relativistic explosion known as a long-durationgamma-ray burst. One would then expect that long gamma-ray bursts andcore-collapse supernovae should be found in similar galacticenvironments. Here we show that this expectation is wrong. We find thatthe long gamma-ray bursts are far more concentrated on the very brightestregions of their host galaxies than are the core-collapse supernovae.Furthermore, the host galaxies of the long gamma-ray bursts aresignificantly fainter and more irregular than the hosts of thecore-collapse supernovae. Together theseresults suggest thatlong-duration gamma-ray bursts are associated with the most massive starsand may be restricted to galaxies of limited chemical evolution. Ourresults directly imply that long gamma-ray bursts are relatively rare ingalaxies such as our own MilkyWay.

  4. A Search for Microsecond Gamma Ray Bursts From Primordial Black Holes

    SciTech Connect

    Frank Krennrich

    2004-08-12

    The project is called SGARFACE (Short Gamma Ray Front Air Cherenkov Experiment) and is an atmospheric Cherenkov detector to provide sensitivity to short bursts of gamma rays of extraterrestrial origin. The detector is an addition to the Whipple 10m gamma ray telescope on Mt. Hopkins in southern Arizona and uses a digital trigger module for recognizing Cherenkov light flashes from gamma ray bursts. The digital trigger modules have been designed, tested and constructed at Iowa State University and have been installed at the Whipple 10m telescope. Operation of the experiment started in March 2003 and data collecting will likely continue until spring of 2005. A final results paper addressing a search for primordial black holes is likely to be finished by summer of 2005.

  5. A study of gamma ray burst continuum properties presnting evidence for two spectral states in bursts

    NASA Technical Reports Server (NTRS)

    Pendleton, Geoffrey N.; Paciesas, William S.; Mallozzi, Robert S.; Koshut, Tom M.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Harmon, B. A.; Lestrade, J. P.

    1994-01-01

    Evidence is presented for the existence of two spectral states contributing simultaneously to the total spectrum observed in many gamma-ray bursts (GRB's). An ensemble of 120 GRB's measured by BATSE were studied, using 4 channel spectral data, to determine in which bursts the spectral states can be most effectively resolved. The technique of summing the low intensity spectra together to get an average spectrum allows for precise characterization of the average low intensity spectral behavior. The 4 and 16 channel spectra obtained by the BATSE Large Area Detectors (LAD's) are analyzed using a model-independent spectral inversion technique. The results of these analyses applied to an individual burst are discussed in detail.

  6. New activity in the Dorado gamma-ray burst source

    SciTech Connect

    Golenetskii, S.V.; Mazets, E.P.; Aptekar, R.L.

    1982-11-01

    On 1981 December 1 and 1982 January 2 the Cone detectors aboard the Venera 13 and Venera 14 probes recorded ..gamma..-ray transients generated by the same source in Dorado as the notable sequence of events observed 1979 March 5, 6 and April 4, 24.

  7. Real-Time Optical Flux Limits from Gamma-Ray Bursts Measured by the Gamma-Ray Optical Counterpart Search Experiment

    NASA Technical Reports Server (NTRS)

    Park, H. S. (Editor); Ables, E. (Editor); Band, D. L. (Editor); Barthelmy, S. D. (Editor); Bionta, R. M. (Editor); Butterworth, P. S. (Editor); Cline, T. L. (Editor); Ferguson, D. H. (Editor); Fishman, G. J. (Editor); Gehrels, N. (Editor); Hurley, K. (Editor); Kouveliotou, C. (Editor); Lee, B. C. (Editor); Meegan, C. A. (Editor); Ott, L. L. (Editor); Parker, E. L. (Editor)

    1997-01-01

    The Gamma-Ray Optical Counterpart Search Experiment presents new experimental upper limits on the optical flux from gamma-ray bursts (GRBs). Our experiment consisted of a fully automated very wide-field opto-electronic detection system that imaged locations of GRBs within a few seconds of receiving trigger signals provided by BATSE's real-time burst coordinate distribution network. The experiment acquired 3800 observing hours, recording 22 gamma-ray burst triggers within approx. 30 s of the start of the burst event. Some of these bursts were imaged while gamma-ray radiation was being detected by BATSE. We identified no optical counterparts associated with gamma-ray bursts among these events at the mV approx. 7.0-8.3 sensitivity level. We find the ratio of the upper limit to the V-band optical flux, F nu, to the gamma-ray fluence, Phi gamma, from these data to be 1 x 10(exp-18) less than F nu Phi gamma less than 2 x 10(exp -16).

  8. 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.

  9. A gamma-ray burst fireball model via the compression and heating of binary neutron stars

    SciTech Connect

    Mathews, G J; Salmonson, J; Wilson, J R

    1999-06-11

    A model is proposed for gamma-ray bursts based upon general relativistic hydrodynamic studies of the compression, heating, and collapse of close binary neutron stars as they approach their last stable orbit. Relativistic compression and heating before collapse may produce a neutrino burst of {approx} 10{sup 53} ergs lasting several seconds. The associated thermal neutrino emission produces an e{sup +}e{sup -} pair plasma by {nu}{bar {nu}} annihilation. We present a hydrodynamic simulation of the formation and evolution of the pair plasma associated with the neutrino burst. We find that this pair plasma leads to the production of {approx} 10{sup 51} - 10{sup 52} ergs in {gamma}-rays with spectral and temporal properties consistent with observed gamma-ray bursts.

  10. Rapid optical variability of the gamma-ray burst grb 080319b and its central engine

    NASA Astrophysics Data System (ADS)

    Beskin, G.; Karpov, S.; Bondar, S.; Guarnieri, A.; Bartolini, C.; Greco, D.; Piccioni, A.

    2010-07-01

    The results of observations of the optical emission that accompanied the gamma-ray burst GRB 080319B are reported. Observations were made using the TORTORA fast wide-field camera mounted on the REM robotic telescope in Chile. The behavior of the light curve before, during, and after the gamma-ray burst is described. The light curve consists of four, possibly periodic, 5-7 s long peaks 8-9 s apart. The behavior of the burst in the gamma and optical energy ranges are compared and the results of the theoretical interpretation of this comparison are reported.

  11. Conical fireballs, cannonballs, and jet breaks in the afterglows of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon

    2013-10-01

    The jet break in the X-ray afterglow of gamma ray bursts (GRBs) appears to be correlated to other properties of the X-ray afterglow and the prompt gamma ray emission, but the correlations are at odds with those predicted by the conical fireball (FB) model of GRBs. They are in good agreement, however, with those predicted by the cannonball (CB) model of GRBs.

  12. Search for time-correlated optical flashes of GRO-detected gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Greiner, J.; Wenzel, W.; Hudec, R.; Moskalenko, E. I.; Fishman, G. J.; Kouveliotou, C.; Meegan, C. A.; Paciesas, W. S.; Wilson, R. B.

    1992-01-01

    This status report presents some details on the project 'Search for time-correlated optical counterparts of gamma-ray bursters'. The photographic sky patrol of the three observatories Sonneberg (FRG), Ondrejov (CSFR), and Odessa (USSR) is used to look for patrol plates which have been exposed simultaneously with a gamma-ray burst detected by GRO. Our expectations and the very first results are presented.

  13. Is the Narrow E-Peak Distribution of Gamma-Ray Bursts Real?

    NASA Technical Reports Server (NTRS)

    Brainerd, Jerome J.

    2000-01-01

    Over the performance period of the research grant, the authors conducted a study of the role that the detector response plays in the detection of gamma-ray bursts. The goal of the study was to determine whether the fact that the gamma-ray bursts observed by the BATSE instrument on the Compton Gamma-ray Observatory are characterized by approximately the same characteristic energy is a consequence of the instrument's characteristics, or whether the distribution is a physical attribute of gamma-ray bursts. The authors succeeded in showing that instrumental effects are mild, and that the observed characteristic energy is a physical attribute of bursts. In the course of this research, the authors ported the computer code for calculating the BATSE detector response matrices to the Sun Solaris platform, and created a version of the code that runs under any platform that supports a Fortran 77 compiler with DEC extensions. This code has already been used by other investigators to analyze BATSE data. The authors constructed a Monte Carlo simulation of the BATSE burst trigger, with which they determined the efficiency of detecting a burst as a function of characteristic burst spectral energy. The results were then applied to BATSE observations to determine the physical model for the distribution of burst characteristic energies.

  14. Is the Narrow E-Peak Distribution of Gamma-Ray Bursts Real?

    NASA Technical Reports Server (NTRS)

    Brainerd, Jerome J.

    2000-01-01

    Over the performance period of the research grant, the authors conducted a study of the role that the detector response plays in the detection of gamma-ray bursts. The goal of the study was to determine whether the fact that the gamma-ray bursts observed by the BATSE instrument on the Compton Gamma-ray Observatory are characterized by approximately the same characteristic energy is a consequence of the instrument's characteristics, or whether the distribution is a physical attribute of gamma-ray bursts. The authors succeeded in showing that instrumental effects are mild, and that the observed characteristic energy is a physical attribute of bursts. In the course of this research, the authors ported the computer code for calculating the BATSE detector response matrices to the Sun Solaris platform, and created a version of the code that runs under any platform that supports a Fortran 77 compiler with DEC extensions. This code has already been used by other investigators to analyze BATSE data. The authors constructed a Monte Carlo simulation of the BATSE burst trigger, with which they determined the efficiency of detecting a burst as a function of characteristic burst spectral energy. The results were then applied to BATSE observations to determine the physical model for the distribution of burst characteristic energies.

  15. Gamma-ray bursts as a probe of large-scale structure in the universe

    NASA Technical Reports Server (NTRS)

    Lamb, D. Q.; Quashnock, Jean M.

    1993-01-01

    If gamma-ray bursts are cosmological in origin, the sources of the bursts are expected to trace the large-scale structure of luminous matter in the universe. We show that, if this is so and if the Burst and Transient Source Experiment yields the locations of approximately greater than 3000 gamma-ray bursts, it may be possible to use them to probe the structure of luminous matter on the largest scales known, consistent with recent determinations from pencil beam surveys and studies of superclusters. A positive result would provide compelling evidence that most gamma-ray bursts are cosmological in origin and would allow comparison between the distributions of luminous matter and dark matter on large scales. Conversely, a negative result might cast doubt on the cosmological origin of the bursts, provide evidence that the clustering of burst sources on large scales is less than that expected from pencil beam surveys and studies of superclusters, or indicate that gamma-ray bursts have some more exotic origin.

  16. On the Recently Discovered Correlations between Gamma-Ray and X-Ray Properties of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Dado, Shlomo; Dar, Arnon

    2013-09-01

    Recently, many correlations between the prompt γ-ray emission properties and the X-ray afterglow properties of gamma-ray bursts (GRBs) have been inferred from a comprehensive analysis of the X-ray light curves of more than 650 GRBs measured with the Swift X-Ray Telescope (Swift/XRT) during the years 2004-2010. We show that these correlations are predicted by the cannonball (CB) model of GRBs. They result from the dependence of GRB observables on the bulk motion Lorentz factor and viewing angle of the jet of highly relativistic plasmoids (CBs) that produces the observed radiations by interaction with the medium through which it propagates. Moreover, despite their different physical origins, long GRBs (LGRBs) and short-hard bursts (SHBs) in the CB model share similar kinematic correlations, which can be combined into triple correlations satisfied by both LGRBs and SHBs.

  17. BATSE observations of gamma-ray burst spectra. 2: Peak energy evolution in bright, long bursts

    NASA Technical Reports Server (NTRS)

    Ford, L. A.; Band, D. L.; Matteson, J. L.; Briggs, M. S.; Pendleton, G. N.; Preece, R. D.; Paciesas, W. S.; Teegarden, B. J.; Palmer, D. M.; Schaefer, B. E.

    1995-01-01

    We investigate spectral evolution in 37 bright, long gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) spectroscopy detectors. High-resolution spectra are chracterized by the energy of the peak of nu F(sub nu), and the evolution of this quantity is examined relative to the emission intensity. In most cases it is found that this peak energy either rises with or slightly precedes major intensity increases and softens for the remainder of the pulse. Interpulse emission is generally harder early in the burst. For bursts with multiple intensity pulses, later spikes tend to be softer than earlier ones, indicating that the energy of the peak of nu F(sub nu) is bounded by an envelope which decays with time. Evidence is found that bursts in which the bulk of the flux comes well after the event which triggers the instrument tend to show less peak energy variability and are not as hard as several bursts in which the emission occurs promptly after the trigger. Several recently proposed burst models are examined in light of these results and no qualitative conflicts with the observations presented here are found.

  18. Investigation of primordial black hole bursts using interplanetary network gamma-ray bursts

    SciTech Connect

    Ukwatta, Tilan Niranjan; Hurley, Kevin; MacGibbon, Jane H.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Pal'Shin, V. D.; Goldsten, J.; Boynton, W.; Kozyrev, A. S.; Rau, A.; von Kienlin, A.; Zhang, X.; Connaughton, V.; Yamaoka, K.; Ohno, M.; Ohmori, N.; Feroci, M.; Cline, T.; Gehrels, N.; Krimm, H. A.; McTiernan, J.

    2016-07-25

    The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 1013–1018 cm (7–105 au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Furthermore, assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.

  19. Investigation of primordial black hole bursts using interplanetary network gamma-ray bursts

    DOE PAGES

    Ukwatta, Tilan Niranjan; Hurley, Kevin; MacGibbon, Jane H.; ...

    2016-07-25

    The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected bymore » the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 1013–1018 cm (7–105 au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Furthermore, assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.« less

  20. Investigation of primordial black hole bursts using interplanetary network gamma-ray bursts

    SciTech Connect

    Ukwatta, Tilan Niranjan; Hurley, Kevin; MacGibbon, Jane H.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Pal'Shin, V. D.; Goldsten, J.; Boynton, W.; Kozyrev, A. S.; Rau, A.; von Kienlin, A.; Zhang, X.; Connaughton, V.; Yamaoka, K.; Ohno, M.; Ohmori, N.; Feroci, M.; Cline, T.; Gehrels, N.; Krimm, H. A.; McTiernan, J.

    2016-07-25

    The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 1013–1018 cm (7–105 au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Furthermore, assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.