Journal articles: 'Gamma-rays: burst'

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Fishman, Gerald J. "Gamma-Ray Burst Observations with BATSE." Symposium - International Astronomical Union 188 (1998): 159–62. http://dx.doi.org/10.1017/s0074180900114664.

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Gamma-ray bursts (GRBs) will be recorded as one of the outstanding new phenomena discovered in astronomy this century. About once per day, a burst of gamma rays appears from a random direction on the sky. Often, the burst outshines all other sources of gamma-rays in the sky, combined. This paper reviews some of the key observed phenomenon of bursts in the hard x-ray/gamma-ray region, as observed with the BATSE experiment on the Compton Gamma Ray Observatory. The observed time profiles, spectral properties and durations of gamma-ray bursts cover a wide range. Recent breakthroughs in the observation of gamma-ray burst counterparts and afterglows in other wavelength regions have marked the beginning of a new era in gamma-ray burst research. Those observations are described in following papers in these proceedings.

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Chadwick, Paula M. "Very high-energy gamma rays from gamma-ray bursts." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 365, no. 1854 (February 9, 2007): 1343–56. http://dx.doi.org/10.1098/rsta.2006.1971.

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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.

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Epstein, Richard I. "Physical Constraints on Models of Gamma-Ray Bursters." International Astronomical Union Colloquium 89 (1986): 305–21. http://dx.doi.org/10.1017/s0252921100086140.

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AbstractThe power per logarithmic bandwidth in gamma-ray burst spectra generally increases rapidly with energy through the x-ray range and does not cut off sharply above a few MeV. This spectral form indicates that a very small fraction of the energy from a gamma-ray burst source is emitted at low energies or is reprocessed into x-rays and that the high-energy gamma rays are not destroyed by photon-photon interactions. The implications are that the emission mechanism for the gamma-ray bursts is not synchrotron radiation from electrons that lose most of their energy before being re-accelerated and that either the regions from which the gamma rays are emitted are large compared to the size of a neutron star or the emission is collimated and beamed away from the stellar surface.

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BARSHAY, SAUL, and GEORG KREYERHOFF. "VERY HIGH-ENERGY NEUTRINOS FROM SLOWLY DECAYING, MASSIVE DARK MATTER AS A SOURCE OF EXPLOSIVE ENERGY FOR GAMMA-RAY BURSTS." Modern Physics Letters A 18, no. 07 (March 7, 2003): 477–89. http://dx.doi.org/10.1142/s0217732303009654.

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We consider a speculative model for gamma-ray bursts (GRB), which predicts that the total kinetic energy in the ejected matter is less than the total energy in the gamma rays. There is also secondary energy in X-rays, which are emitted contemporaneously with the gamma rays. The model suggests that bremsstrahlung and Compton up-scattering by very energetic electrons, are important processes for producing the observed burst radiation. The dynamics naturally allows for the possibility of a moderate degree of beaming of matter and radiation in some gamma-ray bursts. GRB are predicted to have an intrinsically wide distribution in total energies, in particular, on the low side. They are predicted to occur at large redshifts, z ~ 8, in local regions of dense matter.

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Harding, Alice K. "Gamma-Ray Burst Theory: Back to the Drawing Board." International Astronomical Union Colloquium 142 (1994): 863–68. http://dx.doi.org/10.1017/s0252921100078222.

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AbstractGamma-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 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.Subject headings: acceleration of particles — gamma rays: bursts

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van Eerten, Hendrik. "Gamma-ray burst afterglow blast waves." International Journal of Modern Physics D 27, no. 13 (October 2018): 1842002. http://dx.doi.org/10.1142/s0218271818420026.

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The various stages of baryonic gamma-ray burst (GRB) afterglow blast waves are reviewed. These are responsible for the afterglow emission from which much of our understanding of gamma-ray bursts derives. Initially, the blast waves are confined to the dense medium surrounding the burster (stellar envelope or dense wind), giving rise to a jet-cocoon structure. A massive ejecta is released and potentially fed by ongoing energy release from the burster and a forward–reverse shock system is set up between ejecta and ambient density. Ultimately the blast wave spreads sideways and slows down, and the dominant afterglow emission shifts from X-rays down to radio. Over the past years significant progress has been made both observationally and theoretically/numerically in our understanding of these blast waves, unique in the universe due to their often incredibly high initial Lorentz factors of 100–1000. The recent discovery of a short gamma-ray burst counterpart to a gravitational wave detection (GW 170817) brings the promise of a completely new avenue to explore and constrain the dynamics of gamma-ray burst blast waves.

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Coelho, Jaziel G., Luana N. Padilha, Rita C. dos Anjos, Cynthia V. Ventura, and Geanderson A. Carvalho. "An updated view and perspectives on high-energy gamma-ray emission from SGR J1935+2154 and its environment." Journal of Cosmology and Astroparticle Physics 2022, no. 10 (October 1, 2022): 041. http://dx.doi.org/10.1088/1475-7516/2022/10/041.

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Abstract SGR J1935+2154 was discovered in 2016 and is currently one of the most burst-active Soft Gamma-ray Repeaters (SGR), having emitted many X-ray bursts in recent years. In one of our previous articles, we investigated the contribution to high-energy and very high-energy gamma-ray emission (VHE, E > 100 GeV) due to cosmic-ray acceleration of SNR G57.2+0.8 hosting SGR J1935+2154 using the GALPROP propagation code. However, follow-up observations of SGR 1935+2154 were made for 2 hours on April 28, 2020, using the High Energy Stereoscopic System (H.E.S.S.). The observations coincide with X-ray bursts detected by INTEGRAL and Fermi/Gamma-ray Burst Monitor (GBM). These are the first high-energy gamma-ray observations of an SGR in a flaring state, and upper limits on sustained and transient emission have been derived. Now that new H.E.S.S. observations have been made, it is interesting to update our model with respect to these new upper limits. We extend our previous results to a more general situation using the new version of GALPROP. We obtain a hadronic model that confirms the results discussed by H.E.S.S. . This leads to an optimistic prospect that cosmic ray gamma rays from SGR J1935+2154 can contribute to the overall gamma energy density distribution and in particular to the diffusion gamma rays from the Galactic center.

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Hurley, Kevin. "Observational Features of Cosmic Gamma-Ray Bursts: Evidence for Galactic Versus Extragalactic Origin." International Astronomical Union Colloquium 142 (1994): 857–61. http://dx.doi.org/10.1017/s0252921100078210.

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AbstractThe recent observational data on gamma-ray bursts are reviewed. Burst time histories display features at the millisecond level which suggest a compact object origin. Lines in the energy spectra and spectral evolution point toward a Galactic neutron star origin, even though line features have not yet been confirmed in recent data. The Galactic distribution of burst sources, however, is both isotropic and sampled to its characteristic distance, making it unlikely that the sources are related to populations of Galactic neutrons stars we are familiar with. Counterpart searches, previously carried out years after the gamma-ray bursts, are now proceeding days after the events. Based on the current data, it is impossible to conclude whether bursters are Galactic, extragalactic, or both. Data being returned from current experiments, as well as data from new experiments to be launched in the next few years, may yet provide the answer.Subject heading: gamma rays: bursts

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Vestrand, W. T., J. A. Wren, A. Panaitescu, P. R. Wozniak, H. Davis, D. M. Palmer, G. Vianello, et al. "The Bright Optical Flash and Afterglow from the Gamma-Ray Burst GRB 130427A." Science 343, no. 6166 (November 21, 2013): 38–41. http://dx.doi.org/10.1126/science.1242316.

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

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MÉSZÁROS, PETER. "GAMMA-RAY BURSTS AS VHE-UHE SOURCES." International Journal of Modern Physics D 17, no. 09 (September 2008): 1319–32. http://dx.doi.org/10.1142/s0218271808012875.

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Gamma-ray bursts are capable of accelerating cosmic rays up to GZK energies Ep ~ 1020 eV, which can lead to a flux at Earth comparable to that observed by large EAS arrays such as Auger. The semi-relativistic outflows inferred in GRB-related hypernovae are also likely sources of somewhat lower energy cosmic rays. Leptonic processes, such as 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 interactions also produce neutrinos at energies ranging from sub-TeV to EeV, which will be probed with forthcoming experiments such as IceCube, ANITA and KM3NeT. This would provide information about the fundamental interaction physics, the acceleration mechanism, the nature of the sources and their environment.

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KAPPES, ALEXANDER. "GAMMA-RAY BURST DETECTION WITH ICECUBE." International Journal of Modern Physics D 18, no. 10 (October 2009): 1561–65. http://dx.doi.org/10.1142/s0218271809015473.

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With their narrow emission window gamma-ray bursts (GRBs) are among the most promising objects for the first identification of high-energy cosmic neutrinos. If a considerable fraction of the ultra-high energy cosmic rays is indeed produced in GRBs, IceCube, which is now more than half-way completed, should be able to detect the associated neutrinos in the next few years. Furthermore, optical follow-up observations of neutrino multiplets will enhance IceCube's sensitivity to choked GRBs which do not produce a gamma-ray signal.

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MARTÍN, OSMEL, ROLANDO CÁRDENAS, JORGE E. HORVATH, and LIUBA PEÑATE. "EFFECTS OF GALACTIC GAMMA RAYS BURSTS ON PLANETARY ATMOSPHERES." International Journal of Modern Physics E 20, supp02 (December 2011): 67–70. http://dx.doi.org/10.1142/s021830131104061x.

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We discuss the potential past incidence of a galactic gamma ray burst on Earth. Rough estimates for the relative frequencies of this kind of event are given, for the different eons of our planet's geological history. Additionally, we explore the effectiveness of the ozone layer of different paleo-atmospheres to shield the surface of the planet from the ultraviolet flash, which arises as a short-term effect after the incidence of a galactic gamma ray burst.

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Jordana-Mitjans, N., C. G. Mundell, C. Guidorzi, R. J. Smith, E. Ramírez-Ruiz, B. D. Metzger, S. Kobayashi, et al. "A Short Gamma-Ray Burst from a Protomagnetar Remnant." Astrophysical Journal 939, no. 2 (November 1, 2022): 106. http://dx.doi.org/10.3847/1538-4357/ac972b.

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Abstract The contemporaneous detection of gravitational waves and gamma rays from GW170817/GRB 170817A, followed by kilonova emission a day after, confirmed compact binary neutron star mergers as progenitors of short-duration gamma-ray bursts (GRBs) and cosmic sources of heavy r-process nuclei. However, the nature (and life span) of the merger remnant and the energy reservoir powering these bright gamma-ray flashes remains debated, while the first minutes after the merger are unexplored at optical wavelengths. Here, we report the earliest discovery of bright thermal optical emission associated with short GRB 180618A with extended gamma-ray emission—with ultraviolet and optical multicolor observations starting as soon as 1.4 minutes post-burst. The spectrum is consistent with a fast-fading afterglow and emerging thermal optical emission 15 minutes post-burst, which fades abruptly and chromatically (flux density F ν ∝ t −α , α = 4.6 ± 0.3) just 35 minutes after the GRB. Our observations from gamma rays to optical wavelengths are consistent with a hot nebula expanding at relativistic speeds, powered by the plasma winds from a newborn, rapidly spinning and highly magnetized neutron star (i.e., a millisecond magnetar), whose rotational energy is released at a rate L th ∝ t −(2.22±0.14) to reheat the unbound merger-remnant material. These results suggest that such neutron stars can survive the collapse to a black hole on timescales much larger than a few hundred milliseconds after the merger and power the GRB itself through accretion. Bright thermal optical counterparts to binary merger gravitational wave sources may be common in future wide-field fast-cadence sky surveys.

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Adriani, O., Y. Akaike, K. Asano, Y. Asaoka, E. Berti, G. Bigongiari, W. R. Binns, et al. "CALET Search for Electromagnetic Counterparts of Gravitational Waves during the LIGO/Virgo O3 Run." Astrophysical Journal 933, no. 1 (July 1, 2022): 85. http://dx.doi.org/10.3847/1538-4357/ac6f53.

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Abstract The CALorimetric Electron Telescope (CALET) on the International Space Station consists of a high-energy cosmic-ray CALorimeter (CAL) and a lower-energy CALET Gamma-ray Burst Monitor (CGBM). CAL is sensitive to electrons up to 20 TeV, cosmic-ray nuclei from Z = 1 through Z ∼ 40, and gamma rays over the range 1 GeV–10 TeV. CGBM observes gamma rays from 7 keV to 20 MeV. The combined CAL-CGBM instrument has conducted a search for gamma-ray bursts (GRBs) since 2015 October. We report here on the results of a search for X-ray/gamma-ray counterparts to gravitational-wave events reported during the LIGO/Virgo observing run O3. No events have been detected that pass all acceptance criteria. We describe the components, performance, and triggering algorithms of the CGBM—the two Hard X-ray Monitors consisting of LaBr3(Ce) scintillators sensitive to 7 keV–1 MeV gamma rays and a Soft Gamma-ray Monitor BGO scintillator sensitive to 40 keV–20 MeV—and the high-energy CAL consisting of a charge detection module, imaging calorimeter, and the fully active total absorption calorimeter. The analysis procedure is described and upper limits to the time-averaged fluxes are presented.

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Merck, M., D. L. Bertsch, B. L. Dingus, C. E. Fichtel, R. C. Hartman, S. D. Hunter, G. Kanbach, et al. "Observations of High-energy Gamma-ray Bursts with EGRET." International Astronomical Union Colloquium 151 (1995): 358–62. http://dx.doi.org/10.1017/s0252921100035351.

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Gamma Ray Bursts (GRBs) have puzzled astronomers since their discovery more than 20 years ago. As no counterparts at wavelengths other than X- and γ-rays have yet been found the identification of the sources is still missing. Theoretical explanations range from colliding comets (1993) and merging neutron stars (1982) to more exotic objects, such as superconducting cosmic strings (1988). Data accumulated until now still do not discriminate between these models, although results from the BATSE (Burst and Transient Source Experiment) instrument aboard the Compton Gamma Ray Observatory (CGRO) strongly favor extragalactic models.The Energetic Gamma Ray Experiment Telescope (EGRET) aboard CGRO has s ofar detected photons from 5 GRBs with its spark chamber. These are the highest energy γ-rays associated with GRBs to date. In this work we review previously published data and summarize the properties of these events. Elsewhere we present possible constraints from the data on the models proposed to explain GRBs.

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Sato, Yuri, Kaori Obayashi, Ryo Yamazaki, Kohta Murase, and Yutaka Ohira. "Off-axis jet scenario for early afterglow emission of low-luminosity gamma-ray burst GRB 190829A." Monthly Notices of the Royal Astronomical Society 504, no. 4 (May 7, 2021): 5647–55. http://dx.doi.org/10.1093/mnras/stab1273.

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ABSTRACT Recently, ground-based Imaging Atmospheric Cherenkov Telescopes have reported the detection of very-high-energy (VHE) gamma-rays from some gamma-ray bursts (GRBs). One of them, GRB 190829A, was triggered by the Swift satellite, and about 2 × 104 s after the burst onset the VHE gamma-ray emission was detected by H.E.S.S. with ∼5σ significance. This event had unusual features of having much smaller isotropic equivalent gamma-ray energy than typical long GRBs and achromatic peaks in X-ray and optical afterglow at about 1.4 × 103 s. Here, we propose an off-axis jet scenario that explains these observational results. In this model, the relativistic beaming effect is responsible for the apparently small isotropic gamma-ray energy and spectral peak energy. Using a jetted afterglow model, we find that the narrow jet, which has the initial Lorentz factor of 350 and the initial jet opening half-angle of 0.015 rad, viewed off-axis can describe the observed achromatic behaviour in the X-ray and optical afterglow. Another wide, baryon-loaded jet is necessary for the later-epoch X-ray and radio emissions. According to our model, the VHE gamma rays observed by H.E.S.S. at 2 × 104 s may come from the narrow jet through the synchrotron self-Compton process.

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Hartmann, Dieter H., Lawrence E. Brown, Lih-Sin The, Eric V. Linder, Vahé Petrosian, George R. Blumenthal, and Kevin C. Hurley. "Do Gamma-Ray Bursts Originate from an Extended Galactic Halo of High-Velocity Neutron Stars?" International Astronomical Union Colloquium 142 (1994): 893–97. http://dx.doi.org/10.1017/s0252921100078271.

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AbstractThe γ-ray burst brightness distribution is inhomogeneous and the distribution on the sky is nearly isotropic. These features argue against an association of γ-ray bursts with those Galactic objects that are known to exhibit a strong concentration toward the Galactic center or plane. The observed statistical properties indicate a cosmological origin. Circumstantial evidence suggests that neutron stars are involved in the burst phenomenon. Here we consider Population II neutron stars in an extended Galactic Halo (EGH) as an alternative to cosmological scenarios. The BATSE data indicate a small deviation from isotropy near the 2 σ level of statistical significance. If confirmed for an increasing number of bursts, these anisotropies could rule out cosmological scenarios. On the other hand, EGH models require small anisotropies like those observed by BATSE. We consider simple distribution models to determine the generic properties such halos must have to be consistent with the observations and discuss the implications of the corresponding distance scale on burst models.Subject headings: gamma rays: bursts — stars: neutron — stars: Population II — stars: statistics

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Biscoveanu, Sylvia, Eric Thrane, and Salvatore Vitale. "Constraining Short Gamma-Ray Burst Jet Properties with Gravitational Waves and Gamma-Rays." Astrophysical Journal 893, no. 1 (April 14, 2020): 38. http://dx.doi.org/10.3847/1538-4357/ab7eaf.

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Sommer, M., D. L. Bertsch, B. L. Dingus, C. E. Fichtel, G. J. Fishman, A. K. Harding, R. C. Hartman, et al. "High-energy gamma rays from the intense 1993 January 31 gamma-ray burst." Astrophysical Journal 422 (February 1994): L63. http://dx.doi.org/10.1086/187213.

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Chadwick, P. M., J. E. Dickinson, M. R. Dickinson, N. A. Dipper, J. Holder, T. J. L. McComb, K. J. Orford, et al. "A burst of pulsed VHE gamma rays from AE Aquarii." Astroparticle Physics 4, no. 2 (December 1995): 99–111. http://dx.doi.org/10.1016/0927-6505(95)00035-1.

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ZHANG, BING. "GAMMA-RAY BURST PROMPT EMISSION." International Journal of Modern Physics D 23, no. 02 (January 29, 2014): 1430002. http://dx.doi.org/10.1142/s021827181430002x.

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The origin of gamma-ray burst (GRB) prompt emission, bursts of γ-rays lasting from shorter than one second to thousands of seconds, remains not fully understood after more than 40 years of observations. The uncertainties lie in several open questions in the GRB physics, including jet composition, energy dissipation mechanism, particle acceleration mechanism and radiation mechanism. Recent broad-band observations of prompt emission with Fermi sharpen the debates in these areas, which stimulated intense theoretical investigations invoking very different ideas. I will review these debates, and argue that the current data suggest the following picture: A quasi-thermal spectral component originating from the photosphere of the relativistic ejecta has been detected in some GRBs. Even though in some cases (e.g. GRB 090902B) this component dominates the spectrum, in most GRBs, this component either forms a sub-dominant "shoulder" spectral component in the low energy spectral regime of the more dominant "Band" component, or is not detectable at all. The main "Band" spectral component likely originates from the optically thin region due to synchrotron radiation. The diverse magnetization in the GRB central engine is likely the origin of the observed diverse prompt emission properties among bursts.

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Kryvdyk, Volodymyr. "Particle dynamics in the stellar magnetosphere by gravitational collapse." Proceedings of the International Astronomical Union 6, S271 (June 2010): 383–84. http://dx.doi.org/10.1017/s174392131101790x.

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AbstractThe particle dynamics and in the stellar magnetosphere during gravitational collapse is investigated. The formations of relativistic jets and the generation of the radiation bursts in the stellar magnetosphere by gravitational collapse are considered. As follows from results, the stars on the stage of gravitational collapse must be powerful sources of the relativistic jets and the non-thermal radiation. These jets will formed in the polar caps of collapsing stars magnetospheres, when the stellar magnetic field increases during collapse and the charged particles will be accelerate. These jets will generate the non-thermal radiation. The radiation flux grows with decreasing stellar radius and can be observed in the form of radiation burst in wide band wave- from radio to gamma-ray. These bursts radiation can be observed as gamma- and X- rays bursts.

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Ahlers, Markus, and Lea Halser. "Neutrino fluence from gamma-ray bursts: off-axis view of structured jets." Monthly Notices of the Royal Astronomical Society 490, no. 4 (October 24, 2019): 4935–43. http://dx.doi.org/10.1093/mnras/stz2980.

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ABSTRACT We investigate the expected high-energy neutrino fluence from internal shocks produced in the relativistic outflow of gamma-ray bursts. Previous model predictions have primarily focused on on-axis observations of uniform jets. Here, we present a generalization to account for arbitrary viewing angles and jet structures. Based on this formalism, we provide an improved scaling relation that expresses off-axis neutrino fluences in terms of on-axis model predictions. We also find that the neutrino fluence from structured jets can exhibit a strong angular dependence relative to that of gamma-rays and can be far more extended. We examine this behaviour in detail for the recent short gamma-ray burst GRB 170817A observed in coincidence with the gravitational wave event GW170817.

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Baring, Matthew G. "Gamma-Ray Burst Spectral Breaks and Source Beaming." International Astronomical Union Colloquium 142 (1994): 899–903. http://dx.doi.org/10.1017/s0252921100078283.

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AbstractThe principal discovery of the ComptonGamma-Ray Observatory(GRO) concerning gamma-ray bursts is that these sources are isotropic but with a comparative deficiency of fainter sources, suggesting that they are probably cosmological in origin. If they are at such large distances from Earth then they are extremely luminous and compact. A consequence of this is that two-photon pair production attenuation of the gamma-ray continuum cannot be avoided unless the source radiation is substantially beamed. Most sources do not display gamma-ray turnovers although a few GRB detected byGROexhibit distinct spectral breaks in the MeV range. A derivation of the relationship defining of the degree of beaming in burst sources with spectral breaks due toγ-γattenuation, as a function of source spectral index and break energy, is presented. It is found that sources at distances of ~1 Gpc must typically be beamed with bulk Lorentz factors of around 103-104, indicating powerful bulk acceleration in bursts, although these Lorentz factors are reduced markedly for steep source spectra. Since the source spectra are not strongly Comptonized, such beaming will blueshift the γ-γ attenuation breaks to energies much higher than 1 MeV; an absolute lower bound to the source bulk Lorentz factor is determined from this additional constraint. This blueshifting suggests that those sources with MeV breaks may not be cosmological, or that their breaks are produced by a mechanism that dominates γ-γ attenuation at these energies.Subject headings:gamma-rays: bursts — radiation mechanisms: nonthermal

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Wang, Yun, Tian-Ci Zheng, and Zhi-Ping Jin. "GRB 220426A: A Thermal Radiation–Dominated Gamma-Ray Burst." Astrophysical Journal 940, no. 2 (November 30, 2022): 142. http://dx.doi.org/10.3847/1538-4357/aca017.

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Abstract The physical composition of the ejecta of gamma-ray bursts (GRBs) remains an open question. The radiation mechanism of the prompt gamma rays is also in debate. This problem can be solved for the bursts hosting distinct thermal radiation. However, the events with dominant thermal spectral components are still rare. In this work, we focus on GRB 220426A, a recent event detected by the Fermi Gamma-ray Burst Monitor. The time-resolved and time-integrated data analyses yield very hard low-energy spectral indices and rather soft high-energy spectral indices. This means that the spectra of GRB 220426A are narrowly distributed. And the Bayesian inference results are in favor of the multicolor blackbody model. The physical properties of the relativistic outflow are calculated. Assuming a redshift z = 1.4, the bulk Lorentz factors Γ of the shells are found to be between 274 − 18 + 24 and 827 − 71 + 100 , and the corresponding photosphere radii R ph are in the range of 1.83 − 0.50 + 0.52 × 10 11 and 2.97 − 0.15 + 0.14 × 10 12 cm. Similar to GRB 090902B, the time-resolved properties of GRB 220426A satisfy the observed Γ–L and E p –L correlations, where L is the luminosity of the prompt emission and E p is the spectral peak energy.

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Vilmer, N. "Solar Hard X-Ray and Gamma-Ray Observations from GRANAT." International Astronomical Union Colloquium 142 (1994): 611–21. http://dx.doi.org/10.1017/s0252921100077885.

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AbstractHard X-rays and gamma-rays are the most direct signature of the energetic electrons and ions which are accelerated during solar flares. Since the beginning of 1990 the PHEBUS instrument and the SIGMA anticoincidence shield aboard GRANAT have provided hard X-ray and gamma-ray observations of solar bursts in the energy range 0.075-124 and 0.200-15 MeV, respectively. After a brief description of the experiments, we present some results obtained on solar bursts recorded in 1990 and 1991 June. Special emphasis is given to the results related with particle acceleration during solar flares.The first part of the review is devoted to the constraints obtained on the electron acceleration timescale through the analysis of the temporal characteristics of the bursts. Combined studies of hard X-ray and gamma-ray emissions from PHEBUS and radio emissions from the Nançay Multifrequency Radioheliograph are used to infer constraints on the coronal magnetic topology involved in flares. The characteristics (location, spectrum) of the radio-emitting sources are found to vary within a flare from one hard X-ray peak to the other. Hard X-ray and gamma-ray burst onsets and rapid increases of the > 10 MeV emission are coincident with changes in the associated radio emission pattern. These results will be discussed in the context of the flare energy release.The second part of the paper concerns the heliocentric angle distribution of > 10 MeV events and presents more detailed observations of some of the largest flares in the gamma-ray line and the high-energy domains produced by ultrarelativistic electrons and > 100 MeV nucleon−1 ions. The PHEBUS observations of the gamma-ray line flare of 11 June 1991 have been used to deduce the hardness of the accelerated ion spectrum. The link between the main part of the flare and the late long-lasting >50 MeV emission detected by EGRET/COMPTON is discussed. Finally some observations of the large 1990 May 24 flare which produced a large neutron event at ground level are presented.Subject headings: acceleration of particles — Sun: flares — Sun: radio radiation — Sun: X-rays, gamma rays

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Gupta, Nayantara. "On the gamma ray burst origin of extremely energetic cosmic rays." Astroparticle Physics 31, no. 5 (June 2009): 359–65. http://dx.doi.org/10.1016/j.astropartphys.2009.03.006.

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DERISHEV, E. V. "LIMITS TO THE PHYSICAL PARAMETERS IN EXTRAGALACTIC GAMMA-RAY SOURCES." International Journal of Modern Physics D 18, no. 10 (October 2009): 1523–27. http://dx.doi.org/10.1142/s0218271809015448.

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We examine several constraints on the physical parameters in active galactic nuclei and gamma-ray burst, originating from the assumption that these sources are efficient in converting their energy into gamma-rays. It is shown that in most cases these constraints may be reformulated in terms of bounds on the jet Lorentz factor, for which both the lower and the upper limits can be evaluated.

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HORVATH, J. E. "ENERGETICS OF THE SUPERFLARE FROM SGR1806-20 AND A POSSIBLE ASSOCIATED GRAVITATIONAL WAVE BURST." Modern Physics Letters A 20, no. 36 (November 30, 2005): 2799–804. http://dx.doi.org/10.1142/s0217732305018359.

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We discuss in this paper the energetics of large gamma-ray superflares observed from Soft-Gamma Repeater sources. The last recorded event has in fact ruled out some models for the energy release. For the first time actual information about a possible associated gravitational wave emission may have been gathered from the LIGO data, even in the case that most of the energy was emitted in gamma-rays. Even upper limits on the amplitude of the latter h at the expected frequency fc≤2 kHz may be useful to further constrain the remaining mechanisms.

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Totani, Tomonori. "T[CLC]e[/CLC]V Burst of Gamma-Ray Bursts and Ultra–High-Energy Cosmic Rays." Astrophysical Journal 509, no. 2 (December 20, 1998): L81—L84. http://dx.doi.org/10.1086/311772.

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GALANTE, DOUGLAS, and JORGE ERNESTO HORVATH. "QUANTITATIVE BIOLOGICAL EFFECTS OF GAMMA-RAY BURSTS." International Journal of Modern Physics D 16, no. 02n03 (February 2007): 509–14. http://dx.doi.org/10.1142/s0218271807010328.

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We present a unified, quantitative synthesis of analytical and numerical calculations of the effects caused on an Earth-like planet by a Gamma-Ray Burst (GRB), considering atmospheric and biological implications. The main effects of the illumination by a GRB are classified in four distinct phenomena and analyzed separately, namely: direct γ radiation transmission, UV flash, ozone layer depletion and cosmic rays. The "effectiveness" of each of these effects is compared and lethal distances for significant biological damage are given for each one. We find that the first three effects have potential to cause global environmental changes and biospheric damages, even if the source is located at a great distance (perhaps 100 kpc). In contrast, cosmic rays would only be a serious threat for very close sources.

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Waxman, Eli. "High‐Energy Cosmic Rays from Gamma‐Ray Burst Sources: A Stronger Case." Astrophysical Journal 606, no. 2 (May 10, 2004): 988–93. http://dx.doi.org/10.1086/383116.

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Waxman, Eli. "High Energy Cosmic-Rays and Neutrinos from Cosmological Gamma-Ray Burst Fireballs." Physica Scripta T85, no. 1 (2000): 117. http://dx.doi.org/10.1238/physica.topical.085a00117.

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Liu, Ruo-Yu, Hai-Ming Zhang, and Xiang-Yu Wang. "Constraints on Gamma-Ray Burst Models from GRB 221009A: GeV Gamma Rays versus High-energy Neutrinos." Astrophysical Journal Letters 943, no. 1 (January 1, 2023): L2. http://dx.doi.org/10.3847/2041-8213/acaf5e.

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Abstract Gamma-ray bursts (GRBs) are generally believed to be efficient particle accelerators. In the presence of energetic protons in a GRB jet, interactions between these protons and the intense radiation field of the GRB are supposed to induce an electromagnetic cascade. Electrons/positrons generated in the cascade will produce an additional spectrum of a robust feature, which is in the form of a power-law distribution up to a GeV regime with an index of ≲2. We suggest that measurements of the Fermi Large Area Telescope at the GeV band can provide independent constraints on the key GRB model parameters such as the dissipation radius, the jet’s bulk Lorentz factor, and the baryon loading factor. Taking GRB 221009A, the brightest GRB ever detected, as an example, we show that the constraints from GeV gamma-ray emission may be more stringent than that from the neutrino observation, providing us with deep insight into the origin of GRBs.

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LE COULTRE, P. "SEARCH FOR BURST SIGNALS FROM POINT SOURCES." International Journal of Modern Physics A 20, no. 29 (November 20, 2005): 6962–64. http://dx.doi.org/10.1142/s0217751x05030600.

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A sky survey for flaring point sources emitting high energy gamma rays has been performed with the L 3+ C underground muon spectrometer at LEP, CERN. Data were collected from mid July to October 1999 and from April to November 2000. No signal excesses in any direction have been found with muons above 20, 30, 50 and 100 GeV within one day and longer time windows. The steady muon flux sensitivity is of the order of a few times 10-9 cm-2 s-1 for muon energies above 20 GeV, and between 2 × 10-11 and 5 × 10-10 cm -2 s -1 for muon energies above 20 GeV depending on the source position.

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Oganesyan, G., L. Nava, G. Ghirlanda, and A. Celotti. "Characterization of gamma-ray burst prompt emission spectra down to soft X-rays." Astronomy & Astrophysics 616 (August 2018): A138. http://dx.doi.org/10.1051/0004-6361/201732172.

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Detection of prompt emission by Swift-XRT provides a unique tool to study how the prompt spectrum of gamma-ray bursts (GRBs) extends down to the soft X-ray band. This energy band is particularly important for prompt emission studies, since it is towards low energies that the observed spectral shape is in disagreement with the synchrotron predictions. Unfortunately, the number of cases where XRT started observing the GRB location during the prompt phase is very limited. In this work, we collect a sample of 34 GRBs and perform joint XRT+BAT spectral analysis of prompt radiation, extending a previous study focused on the 14 brightest cases. Fermi-GBM observations are included in the analysis when available (11 cases), allowing the characterization of prompt spectra from soft X-rays to MeV energies. In 62% of the spectra, the XRT data reveal a hardening of the spectrum, well described by introducing an additional, low-energy power-law segment (with index α1) into the empirical fitting function. The break energy below which the spectrum hardens has values between 3 keV and 22 keV. A second power-law (α2) describes the spectrum between the break energy and the peak energy. The mean values of the photon indices are 〈α1〉 = −0.51 (σ = 0.24) and 〈α2〉 = −1.56 (σ = 0.26). These are consistent, within one σ, with the synchrotron values in fast cooling regime. As a test, if we exclude XRT data from the fits we find typical results: the spectrum below the peak energy is described by a power law with 〈α〉 = −1.15. This shows the relevance of soft X-ray data in revealing prompt emission spectra consistent with synchrotron spectra. Finally, we do not find any correlation between the presence of the X-ray break energy and the flux, fluence, or duration of the prompt emission.

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Joshi, Jagdish C., Soebur Razzaque, and Reetanjali Moharana. "Photodisintegrated gamma rays and neutrinos from heavy nuclei in the gamma-ray burst jet of GRB 130427A." Monthly Notices of the Royal Astronomical Society: Letters 458, no. 1 (February 15, 2016): L79—L83. http://dx.doi.org/10.1093/mnrasl/slw023.

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Makino, F. "X-Ray Astronomy Satellite Ginga." International Astronomical Union Colloquium 123 (1990): 41–48. http://dx.doi.org/10.1017/s0252921100076880.

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AbstractThe X-ray astronomy satellite Ginga carries three scientific instruments, the Large Area proportional Counters (LAC), All Sky X-ray Monitor (ASM) and Gamma-ray Burst Detector (GBD). The LAC is the main instrument with an effective area of 4000 cm2 giving it the highest sensitivity to hard X-rays so far achieved. Ginga observed about 250 targets up to the end of 1989.

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Syromyatnikov, A. G. "Electro-gravity spin density waves." International Journal of Geometric Methods in Modern Physics 14, no. 10 (September 13, 2017): 1750146. http://dx.doi.org/10.1142/s0219887817501468.

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It is known that some string models predict that strong bursts of gravitational radiation which should be detectable by LIGO, VIRGO and LISA detectors are accompanied by cosmologic gamma-ray bursts (GRBs). GRBs of low-energy gamma ray are associated with core-collapse supernovae (SN). However, measurements of the X-ray afterglow of very intense GRBs (allow a critical test of GRB theories) disagree with that predicted by widely accepted fireball internal–external shocks models of GRBs. It is also known that in a system of a large number of fermions, pairs of gravitational interaction occur on spontaneous breaking of the vacuum spatial symmetry, accompanied by gravitational mass defect. In another side, the space rays generation mechanism on a method of direct transformation of intergalactic gamma-rays to the proton current on spin shock-waves ensures precise agreement between generated proton currents (spin shock waves theory) with the angular distribution data of Galactic gamma-rays as well as for the individual pulses of gamma-/X-ray bursts. There is a precise confirmation of the generated currents (theory) with the burst radiation data characterized by the standard deviation of [Formula: see text] in intensity in relative units within the sensitivity of the equipment. Thus, it was found that the spin angular momentum conservation law (equation of dynamics of spin shock waves) in the X-ray/gamma ranges is fulfilled exactly in real time. The nature of gamma bursts is largely determined by the influence of powerful external sources. The angular distributions anisotropy of Galactic gamma rays and pulsars are determined by the paradoxes way, so this can only take place under conditions of the isotropy of space–time. In this regard, promising gravity in a Finsler space can have the selected direction in flat Minkowski space metric with torsion as in the Einstein–Cartan theory. Considering the induction of torsion in conformal transformations of tetrades (N-ades in arbitrary dimension N) under the Conformal Gauge Theory of Gravity (CGTG), here is considered an exact cosmological solution with Friedman’s asymptotic in the form of conformal flat Fock’s metrics at large times, describing the stage of decay on a cold dust-like medium of do-not-interacting-among-themselves particles and a light-like isotropic radiation. It is shown that at high times, indeed, the process of enlarging the space–time in the model metrics Friedman conformal is equivalent to Minkowski space with a gradient torsion trace in the CGTG Newtonian limit, accompanied by a polarization effect separation of electric charges induced by an electric field [Formula: see text] is manifested in the formation of plasma-like medium with a zero complete electric charge, that in the later stages of evolution is identical to the Fock’s model of a cold dust-like medium of do-not-interacting-among-themselves particles moving here with the same speed. The trace of torsion on the CGTG formula is freezing into an electromagnetic field spin tensor trace density and [Formula: see text] defined inside a spherical surface, moving at the speed of light, on which experiencing a gap. Therefore, this decision takes the form of an electro-gravity spin density wave, as performed in kinematic and dynamic close connection conditions for theorems on spin shock waves with spin flip at the front of the wave, moving at the speed of light in a vacuum. The theoretical dependence of electro-gravity wave energy output from the size of the emitting object is received. When applied to GRBs, this can give a new mechanism of nonthermal gamma rays production.

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CHAKRABARTI, SANDIP K., and PANKAJ S. JOSHI. "NAKED SINGULARITIES AS CANDIDATES FOR GAMMA-RAY BURSTERS." International Journal of Modern Physics D 03, no. 03 (September 1994): 647–51. http://dx.doi.org/10.1142/s0218271894000782.

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Naked singularities appear naturally in dynamically evolving solutions of Einstein equations involving gravitational collapse of radiation, dust, and perfect fluids provided the rate of accretion is less than a critical value. We propose that the gamma-ray bursters (GRBs) are examples of these naked singularity solutions. For illustration, we show that according to solutions involving spherically symmetric collapse of pure radiation field, the energy Eγ and the observed duration Δt0 of a GRB should satisfy, [Formula: see text] being the fraction (10−2 to 10−3) of energy released as gamma rays and the rest possibly as gravitational waves. All the presently observed GRBs satisfy this condition; those satisfying the condition close to equality must necessarily be of cosmological origin with the red-shift factor z not exceeding ~1−10 depending on exact observed flux, red-shift and conversion efficiency of gamma rays. If GRBs are indeed from naked singular regions, they should also be accompanied by a strong burst of gravitational waves which, if detectible, will constitute a basic test for our model.

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Blustin, Alexander J. "Shock break-out: how a GRB revealed the beginnings of a supernova." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 365, no. 1854 (February 9, 2007): 1263–68. http://dx.doi.org/10.1098/rsta.2006.1968.

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

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Zhang, K., Z. B. Zhang, Y. F. Huang, L. M. Song, S. J. Zheng, X. J. Li, D. Li, and F. F. Su. "How are gamma-ray burst radio afterglows populated?" Monthly Notices of the Royal Astronomical Society 503, no. 3 (February 19, 2021): 3262–78. http://dx.doi.org/10.1093/mnras/stab465.

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ABSTRACT We systematically analyse two GRB samples with radio-loud and radio-quiet afterglows, respectively. It is interestingly found that the radio-selected GRB samples exhibit a clear dichotomy in terms of their distributions of intrinsic durations (Tint), isotropic energies in γ-rays (Eγ, iso), the circum-burst medium density (n), the spectral radio peak luminosity (Lν, p) and flux densities (Fhost) of host galaxies. On average, the values of Tint, Eγ, iso, n, Lν, p, and Fhost of radio-quiet GRBs are relatively smaller than those of radio-loud ones. However, the redshifts and host flux densities of both samples are similarly distributed. In addition, a positive power-law correlation of $L_{\nu ,p}\propto E_{\gamma ,\rm iso}^{0.41\pm 0.04}$ is found for the radio-loud sample, especially in accord with the supernova-associated GRBs, which is marginally consistent with that of the radio-quiet GRB sample. A negative correlation between Tint and z is confirmed to similarly hold for both radio-loud and radio-quiet GRBs. The dividing line between short and long GRBs in the rest frame is at Tint ≃1 s. Consequently, we propose that the radio-selected GRBs could be originated from distinct progenitors and central engines, together with environments.

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Fargion, D., and A. Colaiuda. "Gamma rays precursors and afterglows surrounding UHECR events: Z-burst model is still alive." Nuclear Physics B - Proceedings Supplements 136 (November 2004): 256–62. http://dx.doi.org/10.1016/j.nuclphysbps.2004.10.009.

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Shibata, Sanshiro, and Nozomu Tominaga. "Origin of Ultra-High Energy Cosmic Rays: Nuclear Composition of Gamma-Ray Burst Jets." Proceedings of the International Astronomical Union 7, S279 (April 2011): 389–90. http://dx.doi.org/10.1017/s1743921312013488.

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AbstractUltra-high energy cosmic rays (UHECRs) are the most energetic particles flying from space and their source is not clarified yet. Recently, the Pierre Auger Observatory (PAO) suggests that UHECRs involve heavy nuclei. The PAO results require that a considerable fraction of metal nuclei must exist in the accelerating site, which can be realized only in the stellar interior. This puts strong constraints on the origin of UHECRs. In order to definitize the constraints from PAO results, we investigate the fraction of metal nuclei in a relativistic jet in gamma-ray burst associated with core-collapse supernova. If the jet is initially dominated by radiation field, quasi-statistical equilibrium (QSE) is established and heavy nuclei are dissociated to light particles such as 4He during the acceleration and expansion. On the other hand, if the jet is mainly accelerated by magnetic field heavy or intermediate mass nuclei can survive. The criterion to contain the metal nuclei is that the temperature at the launch site is below 4.5 × 109K. Therefore, if the composition of UHECRs is dominated by metal nuclei, a GRB with the magnetized jet is the most plausible candidate of the accelerating site.

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Bisnovatyi-Kogan, G. S., and A. F. Illarionov. "Low Energy Lines in Spectra of Gamma Bursts." International Astronomical Union Colloquium 115 (1990): 63–69. http://dx.doi.org/10.1017/s0252921100012148.

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AbstractWe connect the phenomenon of gamma ray bursts with nuclear explosions on the old neutron stars. The matter of the neutron star in the non-equilibrium layer at depths of 30 m ≤ h ≥ 100 m consists of superheavy (A ≥ 300) nuclei with a surplus of neutrons (A/Z = 3 ÷ 4). These nuclei are metastable and exist only at high pressure. After the starquake some of the matter from non-equilibrium layer may move upwards and its nuclei become unstable. The β-decay is followed by a chain reaction of fission and nuclear explosion. The gamma ray burst is observed as radiation of the star surface heated to high temperature. Some mass may be ejected, forming expanding cloud. It consists mainly of the iron Fe56 with small (≤ 1%) additions of heavy elements (Ba, I, …) arising from the fission. The passage of stellar gamma radiation through the expanding plasma clouds leads to the formation of short-lived spectral features. Strong absorption of the soft gamma rays on K-electrons of Fe56 must be observed in the early stages. The gamma quanta with energies ε = 40–70 keV beyond the K-edge of the heavy elements (Ba, I, …) are absorbed in the later stages. A wide Kα line (εα = 30 keV) appears simultaneously. The free-free emission of expanding hot plasma cloud may be observed as a short flash in optical band.

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Abbasi, Rasha, John Belz, Ryan Le Von, Dan Rodeheffer, Paul Krehbiel, Jackson Remington, and William Rison. "Ground-Based Observations of Terrestrial Gamma Ray Flashes Associated with Downward-Directed Lightning Leaders." EPJ Web of Conferences 197 (2019): 03002. http://dx.doi.org/10.1051/epjconf/201919703002.

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Terrestrial gamma-ray flashes (TGFs) are bursts of gamma-rays initiated in the Earth’s atmosphere. TGFs were serendipitously first observed over twenty years ago by the BATSE gamma ray satellite experiment. Since then, several satellite experiments have shown that TGFs are produced in the upward negative breakdown stage at the start of intracloud lightning discharges. In this proceeding, we present ground-based observation of TGFs produced by downward negative breakdown occurring at the beginning of negative cloud-to-ground flashes. The Terrestrial gamma-ray flashes discussed in this work were detected between 2014-2017 at ground level by the Telescope Array surface detector (TASD) together with Lightning Mapping Array (LMA) and the slow electric field antenna (SA). The TASD detector is a 700 km2 ultra high energy cosmic ray detector in the southwestern desert of Utah. It is comprised of 507 (3 m2) plastic scintillator detectors on a 1.2 km square grid. The LMA detector, a three-dimensional total lightning location system, is comprised of nine stations located within and around the array. The slow electric field antenna records the electric field change in lightning discharges. The observed Gamma ray showers were detected in the first 1-2 ms of downward negative breakdown prior to cloud-to-ground lightning strikes. The shower sources were observed by the LMA detector at altitudes of a few kilometers above ground level. The detected energetic burst showers have a footprint on the ground typically ~ 3-5 km in diameter. The bursts comprise of several (2-5) individual pulses, each of which have a span of a few to tens of microseconds and an overall duration of several hundred microseconds. Using a forward-beamed cone of half-angle of 16 degrees, GEANT simulation studies indicate that the showers are consistent with gamma rays of 1012 - 1014 primary photons. We hypothesize that the observed terrestrial gamma-ray flashes are similar to those detected by satellites, but that the ground-based observations are closer to the source and therefore are able to observe weaker sources and report on the structure of the temporal distribution at the source. This result and future studies will enable us to better identify and constrain the mechanisms of downward TGF production.

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Misra, Kuntal, and A. S. Fruchter. "Radioactive decay of GRB-SNe at late-times." Proceedings of the International Astronomical Union 12, S331 (February 2017): 45–50. http://dx.doi.org/10.1017/s1743921317004707.

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AbstractWe present the late-time Hubble Space Telescope observations of two Gamma Ray Burst (GRB) associated supernovae (SNe), GRB 030329/SN 2003dh and XRF 060218/SN 2006aj. Using the multi-color data up to ~320 days after the burst, we constrain the late-time decay nature of these SNe. The decay rates of SN 2003dh are steeper than SN 2006aj. A comparison with two other GRB SNe, GRB 980425/SN 1998bw and the SN associated with XRF 020903, shows that the decay rates of SN 2003dh are similar to XRF 020903 and those of SN 2006aj are similar to SN 1998bw. The late-time decay rates are steeper than the 56Co→56Fe radioactive decay rate indicating that there is some leakage of gamma-rays. We also compare the late-time decay rates of nine type Ic SNe, including the SNe of long GRBs, Ic broad lined and normal Ics. The decay rates of the SNe sample show a remarkable similarity in I band at late-times with a scatter of ~10%.

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LEMOINE, MARTIN. "ON ACCELERATION AND PROPAGATION OF ULTRA-HIGH ENERGY COSMIC RAYS." International Journal of Modern Physics D 18, no. 10 (October 2009): 1583–86. http://dx.doi.org/10.1142/s0218271809015497.

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This paper discusses the correlation reported in 2008 by the Pierre Auger Observatory (PAO) of the arrival directions of the highest energy cosmic rays with active galactic nuclei (AGN). It is argued that these correlating AGN do not have the power required to be the sources of ultra-high energy protons. This current PAO dataset is further shown to disfavor giant radio-galaxies (both Fanaroff–Riley type I and II) as sources of ultra-high energy protons. The current data thus likely point to the local large scale structure, in which the actual sources of ultra-high energy cosmic rays camouflage. Finally, it is shown that the last gamma-ray burst in Centaurus A could explain, through rescattering on the Cen A lobes, the apparent cluster of events in this direction.

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Akerlof, C. W., W. Zheng, S. B. Pandey, and T. A. McKay. "SEARCHING FOR NEEDLES IN HAYSTACKS—LOOKING FOR GAMMA-RAY BURST γ-RAYS WITH THEFERMI/LAT DETECTOR." Astrophysical Journal 726, no. 1 (December 10, 2010): 22. http://dx.doi.org/10.1088/0004-637x/726/1/22.

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Metzger, B. D., D. Giannios, and S. Horiuchi. "Heavy nuclei synthesized in gamma-ray burst outflows as the source of ultrahigh energy cosmic rays." Monthly Notices of the Royal Astronomical Society 415, no. 3 (May 30, 2011): 2495–504. http://dx.doi.org/10.1111/j.1365-2966.2011.18873.x.

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Journal articles on the topic 'Gamma-rays: burst'

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