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Sample records for cosmic gamma bursts

  1. Cosmic gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Vedrenne, G.

    1981-06-01

    The general characteristics of gamma-ray bursts are considered. During the period from 1967 to 1977 62 gamma-ray bursts were discovered. Between September 1978 and December 1980 more than 40 bursts were observed with the aid of interplanetary spacecraft, including the Pioneer Venus Orbiter, ISEE-C, Helios B, Vela, Prognoz 7, Venera 11, and Venera 12. The time structures are discussed along with the spectra, and the burst intensity distribution. Attention is given to events observed on March 5, April 6, November 4, and November 19, 1979, taking into account the location of each event. The implications of the more recent results are discussed. It is pointed out that for a better understanding of the origin of the emissions, it is necessary to have a coordinated observation program with several satellites separated by large distances.

  2. Cosmic-Rays and Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Meli, A.

    2013-07-01

    Cosmic-rays are subatomic particles of energies ranging between a few eV to hundreds of TeV. These particles register a power-law spectrum, and it seems that most of them originate from astrophysical galactic and extragalactic sources. The shock acceleration in superalfvenic astrophysical plasmas, is believed to be the main mechanism responsible for the production of the non-thermal cosmic-rays. Especially, the importance of the very high energy cosmic-ray acceleration, with its consequent gamma-ray radiation and neutrino production in the shocks of the relativistic jets of Gamma Ray Bursts, is a favourable theme of study. I will discuss the cosmic-ray shock acceleration mechanism particularly focusing on simulation studies of cosmic-ray acceleration occurring in the relativistic shocks of GRB jets.

  3. The Cosmic Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Djorgovski, S. G.; Frail, D. A.; Kulkarni, S. R.; Sari, R.; Bloom, J. S.; Galama, T. J.; Harrison, F. A.; Price, P. A.; Fox, D.; Reichart, D. E.; Yost, S.; Berger, E.; Diercks, A.; Goodrich, R.; Chaffee, F.

    2002-12-01

    Cosmic γ-ray bursts are one of the great frontiers of astrophysics today. They are a playground of relativists and observers alike. They may teach us about the death of stars and the birth of black holes, the physics in extreme conditions, and help us probe star formation in the distant and obscured universe. In this review we summarise some of the remarkable progress in this field over the past few years. While the nature of the GRB progenitors is still unsettled, it now appears likely that at least some bursts originate in explosions of very massive stars, or at least occur in or near the regions of massive star formation. The physics of the burst afterglows is reasonably well understood, and has been tested and confirmed very well by the observations. Bursts are found to be beamed, but with a broad range of jet opening angles; the mean γ-ray energies after the beaming corrections are ~ 1051 erg. Bursts are associated with faint ( ~ 25 mag) galaxies at cosmological redshifts, with ~ 1. The host galaxies span a range of luminosities and morphologies, but appear to be broadly typical for the normal, actively star-forming galaxy populations at comparable redshifts and magnitudes. Some of the challenges for the future include: the nature of the short bursts and possibly other types of bursts and transients; use of GRBs to probe the obscured star formation in the universe, and possibly as probes of the very early universe; and their detection as sources of high-energy particles and gravitational waves.

  4. 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

  5. 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

  6. 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.

  7. Observational properties of cosmic gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Mazets, E. P.

    1986-01-01

    A brief overview of the major observational results obtained in gamma-ray burst studies is presented. Also discussed is to what extent the thermonuclear model, which appears at present to be the most plausible, can account for the observed properties of the bursts. The investigation of gamma-ray bursts should cover observations of the time histories of events, energy spectra, and their variablility, source localization, and inspection of the localization regions during the active and quiescent phases of the source in other wavelengths, as well as, evaluation of the statistical distributions of the data obtained.

  8. Ulysses/BATSE observations of cosmic gamma ray bursts

    NASA Technical Reports Server (NTRS)

    Hurley, K.; Boer, M.; Sommer, M.; Fishman, G.; Meegan, C.; Paciesas, W.; Wilson, R.; Kouveliotou, C.; Cline, T.

    1992-01-01

    The gamma ray burst detector aboard the ESA-NASA Ulysses spacecraft, in operation since Nov. 1990, has detected numerous gamma bursts in conjunction with the BATSE experiment aboard the Compton Observatory. Initial results are presented on burst locations for three events (21 April, 2 May, and 3 May, 1991) obtained by arrival time analysis, and they are compared with the BATSE locations. The arrival time analysis annuli have typical widths of 5'. The preliminary analysis indicates that both experiments are likely to have unresolved systematic errors, but that further work will improve the location accuracy substantially.

  9. 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.

  10. 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

  11. Gamma-ray bursts from cusps on superconducting cosmic strings at large redshifts

    NASA Technical Reports Server (NTRS)

    Paczynski, Bohdan

    1988-01-01

    Babul et al. (1987) proposed that some gamma-ray bursts may be caused by energy released at the cusps of oscillating loops made of superconducting cosmic strings. It is claimed that there were some errors and omissions in that work, which are claimed to be corrected in the present paper. Arguments are presented, that given certain assumptions, the cusps on oscillating superconducting cosmic strings produce highly collimated and energetic electromagnetic bursts and that a fair fraction of electromagnetic energy is likely to come out as gamma rays.

  12. Physics of the synchrotron model of cosmic gamma-ray bursts

    SciTech Connect

    Liang, E.P.

    1983-09-27

    We review the theoretical arguments leading to the thermal synchrotron model of cosmic gamma-ray bursts. We propose a magnetic flare-resonant absorption mechanism for the production of the hot electrons that can account for most of the unusual properties of the emission layer.

  13. High-redshift gamma-ray bursts: observational signatures of superconducting cosmic strings?

    PubMed

    Cheng, K S; Yu, Yun-Wei; Harko, T

    2010-06-18

    The high-redshift gamma-ray bursts (GRBs), GRBs 080913 and 090423, challenge the conventional GRB progenitor models by their short durations, typical for short GRBs, and their high energy releases, typical for long GRBs. Meanwhile, the GRB rate inferred from high-redshift GRBs also remarkably exceeds the prediction of the collapsar model, with an ordinary star formation history. We show that all these contradictions could be eliminated naturally, if we ascribe some high-redshift GRBs to electromagnetic bursts of superconducting cosmic strings. High-redshift GRBs could become a reasonable way to test the superconducting cosmic string model because the event rate of cosmic string bursts increases rapidly with increasing redshifts, whereas the collapsar rate decreases. PMID:20867291

  14. Gamma-ray bursts from superconducting cosmic strings at large redshifts

    NASA Technical Reports Server (NTRS)

    Babul, Arif; Paczynski, Bohdan; Spergel, David

    1987-01-01

    The relation between cusp events and gamma-rays bursts is investigated. The optical depth of the universe to X-rays and gamma-rays of various energies is calculated and discussed. The cosmological evolution of cosmic strings is examined, and the energetics and time-scales related to the cusp phenomena are estimated. It is noted that it is possible to have energy bursts with a duration of a few seconds or less from cusps at z = 1000; the maximum amount of energy associated with such an event is limited to 10 to the 7th ergs/sq cm.

  15. CAN ULTRAHIGH-ENERGY COSMIC RAYS COME FROM GAMMA-RAY BURSTS? COSMIC RAYS BELOW THE ANKLE AND GALACTIC GAMMA-RAY BURSTS

    SciTech Connect

    Eichler, David; Pohl, Martin

    2011-09-10

    The maximum cosmic-ray energy achievable by acceleration by a relativistic blast wave is derived. It is shown that forward shocks from long gamma-ray bursts (GRBs) in the interstellar medium accelerate protons to large enough energies, and have a sufficient energy budget, to produce the Galactic cosmic-ray component just below the ankle at 4 x 10{sup 18} eV, as per an earlier suggestion. It is further argued that, were extragalactic long GRBs responsible for the component above the ankle as well, the occasional Galactic GRB within the solar circle would contribute more than the observational limits on the outward flux from the solar circle, unless an avoidance scenario, such as intermittency and/or beaming, allows the present-day local flux to be less than 10{sup -3} of the average. Difficulties with these avoidance scenarios are noted.

  16. Are gamma-ray bursts the sources of ultra-high energy cosmic rays?

    NASA Astrophysics Data System (ADS)

    Baerwald, Philipp; Bustamante, Mauricio; Winter, Walter

    2015-03-01

    We reconsider the possibility that gamma-ray bursts (GRBs) are the sources of the ultra-high energy cosmic rays (UHECRs) within the internal shock model, assuming a pure proton composition of the UHECRs. For the first time, we combine the information from gamma-rays, cosmic rays, prompt neutrinos, and cosmogenic neutrinos quantitatively in a joint cosmic ray production and propagation model, and we show that the information on the cosmic energy budget can be obtained as a consequence. In addition to the neutron model, we consider alternative scenarios for the cosmic ray escape from the GRBs, i.e., that cosmic rays can leak from the sources. We find that the dip model, which describes the ankle in UHECR observations by the pair production dip, is strongly disfavored in combination with the internal shock model because (a) unrealistically high baryonic loadings (energy in protons versus energy in electrons/gamma-rays) are needed for the individual GRBs and (b) the prompt neutrino flux easily overshoots the corresponding neutrino bound. On the other hand, GRBs may account for the UHECRs in the ankle transition model if cosmic rays leak out from the source at the highest energies. In that case, we demonstrate that future neutrino observations can efficiently test most of the parameter space - unless the baryonic loading is much larger than previously anticipated.

  17. Cosmic gamma-ray burst detected with an instrument on board the OGO-5 satellite

    NASA Technical Reports Server (NTRS)

    Lheureux, J.

    1974-01-01

    Gamma-ray bursts of cosmic origin have recently been detected by instruments on the Vela satellites. We now confirm the detection of the June 30, 1971 event with an instrument on board the OGO-5 satellite. The intensity of this burst is calculated to be approximately 100-200 photons per sq cm/sec for photons of energy greater than 150 keV with an upper limit of 50 photons per sq cm/sec for the intensity above 5 MeV. An upper limit of one-third of the intensity of the June 30, 1971 event is set for 10 other events studied.

  18. 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.

  19. Gamma-ray bursts and cosmic rays from accretion-induced collapse

    NASA Technical Reports Server (NTRS)

    Dar, Arnon; Kozlovsky, Ben Z.; Nussinov, Shmuel; Ramaty, Reuven

    1992-01-01

    It is shown that the birth of naked or nearly naked neutron stars in accretion-induced collapse or in the bare collapse of white dwarfs can produce cosmological gamma-ray bursts and can provide the required injection rate of cosmic rays into the interstellar space. It is estimated that most of the e(+)e(-) pairs annihilate in flight on a short time scale in the vicinity of the neutron star. It is shown that the gamma-ray bursts, the 0.511 MeV Galactic annihilation radiation, and the cosmic rays exclude the possibility that the large uncertainties in the Galactic pulsar birthrate and the Galactic SN II explosion rate would allow a significant contribution to the pulsar birthrate from naked or nearly naked neutron star formation. The upper bound on the Galactic birthrate of naked or nearly naked neutron stars of less than 1 in 1000 yr makes it very unlikely that a neutrino burst unaccompanied by optical emission from the birth of a naked or nearly naked neutron star will be detected in the near future by underground neutrino telescopes.

  20. The solar flare and cosmic gamma-ray burst experiment aboard the Ulysses spacecraft

    NASA Technical Reports Server (NTRS)

    Boer, Michel; Sommer, Michael; Hurley, Kevin

    1989-01-01

    The HUS-Ulysses team has prepared an instrument for the Ulysses spacecraft consisting of 2 Csi detectors and 2 Si surface barrier detectors for measuring x rays in the range 5 to 200 keV with up to 8 ms time resolution. The prime objectives of the experiment are the study of solar flares and cosmic gamma-ray bursts. The Ulysses mission will leave the ecliptic during the forthcoming solar maximum. The total time above ecliptic latitudes + or - 70 degrees is expected to be 230 days. The solar data can be used in conjunction with other experiments to measure the directivity of the emission and for correlative studies.

  1. Laboratory laser acceleration and high energy astrophysics: {gamma}-ray bursts and cosmic rays

    SciTech Connect

    Tajima, T.; Takahashi, Y.

    1998-08-20

    Recent experimental progress in laser acceleration of charged particles (electrons) and its associated processes has shown that intense electromagnetic pulses can promptly accelerate charged particles to high energies and that their energy spectrum is quite hard. On the other hand some of the high energy astrophysical phenomena such as extremely high energy cosmic rays and energetic components of {gamma}-ray bursts cry for new physical mechanisms for promptly accelerating particles to high energies. The authors suggest that the basic physics involved in laser acceleration experiments sheds light on some of the underlying mechanisms and their energy spectral characteristics of the promptly accelerated particles in these high energy astrophysical phenomena.

  2. Neutrino and cosmic-ray emission from multiple internal shocks in gamma-ray bursts.

    PubMed

    Bustamante, Mauricio; Baerwald, Philipp; Murase, Kohta; Winter, Walter

    2015-01-01

    Gamma-ray bursts (GRBs) are short-lived, luminous explosions at cosmological distances, thought to originate from relativistic jets launched at the deaths of massive stars. They are among the prime candidates to produce the observed cosmic rays at the highest energies. Recent neutrino data have, however, started to constrain this possibility in the simplest models with only one emission zone. In the classical theory of GRBs, it is expected that particles are accelerated at mildly relativistic shocks generated by the collisions of material ejected from a central engine. Here we consider neutrino and cosmic-ray emission from multiple emission regions since these internal collisions must occur at very different radii, from below the photosphere all the way out to the circumburst medium, as a consequence of the efficient dissipation of kinetic energy. We demonstrate that the different messengers originate from different collision radii, which means that multi-messenger observations open windows for revealing the evolving GRB outflows. PMID:25858274

  3. Neutrino and cosmic-ray emission from multiple internal shocks in gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Bustamante, Mauricio; Baerwald, Philipp; Murase, Kohta; Winter, Walter

    2015-04-01

    Gamma-ray bursts (GRBs) are short-lived, luminous explosions at cosmological distances, thought to originate from relativistic jets launched at the deaths of massive stars. They are among the prime candidates to produce the observed cosmic rays at the highest energies. Recent neutrino data have, however, started to constrain this possibility in the simplest models with only one emission zone. In the classical theory of GRBs, it is expected that particles are accelerated at mildly relativistic shocks generated by the collisions of material ejected from a central engine. Here we consider neutrino and cosmic-ray emission from multiple emission regions since these internal collisions must occur at very different radii, from below the photosphere all the way out to the circumburst medium, as a consequence of the efficient dissipation of kinetic energy. We demonstrate that the different messengers originate from different collision radii, which means that multi-messenger observations open windows for revealing the evolving GRB outflows.

  4. A study of the correlation of EHE cosmic rays with Gamma Ray Bursts

    SciTech Connect

    Takahashi, Yoshiyuki

    1998-06-15

    A study of space angles and temporal spacing was made for extremely-high energy (EHE) cosmic ray events to see if there are any correlation with Gamma Ray Bursts (GRB's) recorded by the BATSE experiment on the Compton Gamma Ray Observatory. The results on the most generic correlation using all the recorded GRB's and EHECR's show no significant correlation. Nevertheless, the highest-energy cosmic ray ''pair'' events observed by the AGASA experiments appear to be correlated with the very high fluence GRB's. Some basis to form a GRB and a fireball is discussed. Empirical analysis of the GRB events strongly implied that the photonic field energy density in the source region should have exceeded the electric energy density of Schwinger field. A possible generation of an initial GRB, its fireball and relativistic shocks therein, is considered in terms of Schwinger field generated by radiation pressure of transient, high luminosity photons provided by collective nuclear collisions of neutron matter. Acceleration of electrons, and some protons, may be possible in the radial electrostatic Schwinger field. Ultra-relativistic shocks might also accelerate particles to certain high energies ({gamma}{<=}10{sup 12{center_dot}}{sup 15}). Neutral secondaries, including gamma rays, neutrinos, ''strangelets,'' and Farrar's SUSY S{sub 0} particles, are discussed as plausible EHECR pair candidates from GRB fireballs. The OWL/AIRWATCH may be able to explore them from 4x10{sup 19} eV to well beyond 10{sup 21} eV.

  5. A study of the correlation of EHE cosmic rays with Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Takahashi, Yoshiyuki

    1998-06-01

    A study of space angles and temporal spacing was made for extremely-high energy (EHE) cosmic ray events to see if there are any correlation with Gamma Ray Bursts (GRB's) recorded by the BATSE experiment on the Compton Gamma Ray Observatory. The results on the most generic correlation using all the recorded GRB's and EHECR's show no significant correlation. Nevertheless, the highest-energy cosmic ray ``pair'' events observed by the AGASA experiments appear to be correlated with the very high fluence GRB's. Some basis to form a GRB and a fireball is discussed. Empirical analysis of the GRB events strongly implied that the photonic field energy density in the source region should have exceeded the electric energy density of Schwinger field. A possible generation of an initial GRB, its fireball and relativistic shocks therein, is considered in terms of Schwinger field generated by radiation pressure of transient, high luminosity photons provided by collective nuclear collisions of neutron matter. Acceleration of electrons, and some protons, may be possible in the radial electrostatic Schwinger field. Ultra-relativistic shocks might also accelerate particles to certain high energies (γ<=1012.15). Neutral secondaries, including gamma rays, neutrinos, ``strangelets,'' and Farrar's SUSY S0 particles, are discussed as plausible EHECR pair candidates from GRB fireballs. The OWL/AIRWATCH may be able to explore them from 4×1019 eV to well beyond 1021 eV.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    SciTech Connect

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

    2014-03-01

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

  8. Neutrino and cosmic-ray release from gamma-ray bursts: Time-dependent simulations

    SciTech Connect

    Asano, Katsuaki; Mészáros, Peter E-mail: nnp@psu.edu

    2014-04-10

    We revisit the neutrino and ultra-high-energy cosmic-ray (UHECR) production from gamma-ray bursts (GRBs) with time-dependent simulations for the proton-induced cascades. This method can generate self-consistent photon, neutrino, and escaped neutron spectra. To obtain the integrated background spectra, we take into account the distributions of the burst luminosity and pulse duration timescale. A benchmark case with standard GRB luminosity function, a bulk Lorentz factor Γ = 300, and a proton to gamma-ray luminosity fraction f{sub p} = 10 is consistent with both the neutrino upper limits and the observed UHECR intensity at ∼10{sup 20} eV, while requiring a different type of UHECR source at the ankle. For the benchmark case, the GRBs in the bright end of the luminosity function, which contribute most of the neutrinos, have their photon spectrum substantially distorted by secondary photons. Such bright GRBs are few in number, and reducing their f{sub p} eliminates the distortion and reduces the neutrino production. Even if we neglect the contribution of the brightest GRBs, the UHECR production rate at energies corresponding to the Greisen-Zatsepin-Kuzmin limit is almost unchanged. These nominal GRB models, especially with L {sub iso} ≲ 10{sup 53} erg s{sup –1}, appear to meet the current constraints as far as being candidate UHECR sources above the ankle energy.

  9. Neutrino and Cosmic-Ray Release from Gamma-Ray Bursts: Time-dependent Simulations

    NASA Astrophysics Data System (ADS)

    Asano, Katsuaki; Mészáros, Peter

    2014-04-01

    We revisit the neutrino and ultra-high-energy cosmic-ray (UHECR) production from gamma-ray bursts (GRBs) with time-dependent simulations for the proton-induced cascades. This method can generate self-consistent photon, neutrino, and escaped neutron spectra. To obtain the integrated background spectra, we take into account the distributions of the burst luminosity and pulse duration timescale. A benchmark case with standard GRB luminosity function, a bulk Lorentz factor Γ = 300, and a proton to gamma-ray luminosity fraction fp = 10 is consistent with both the neutrino upper limits and the observed UHECR intensity at ~1020 eV, while requiring a different type of UHECR source at the ankle. For the benchmark case, the GRBs in the bright end of the luminosity function, which contribute most of the neutrinos, have their photon spectrum substantially distorted by secondary photons. Such bright GRBs are few in number, and reducing their fp eliminates the distortion and reduces the neutrino production. Even if we neglect the contribution of the brightest GRBs, the UHECR production rate at energies corresponding to the Greisen-Zatsepin-Kuzmin limit is almost unchanged. These nominal GRB models, especially with L iso <~ 1053 erg s-1, appear to meet the current constraints as far as being candidate UHECR sources above the ankle energy.

  10. Astrophysical explosions: from solar flares to cosmic gamma-ray bursts.

    PubMed

    Wheeler, J Craig

    2012-02-13

    Astrophysical explosions result from the release of magnetic, gravitational or thermonuclear energy on dynamical time scales, typically the sound-crossing time for the system. These explosions include solar and stellar flares, eruptive phenomena in accretion discs, thermonuclear combustion on the surfaces of white dwarfs and neutron stars, violent magnetic reconnection in neutron stars, thermonuclear and gravitational collapse supernovae and cosmic gamma-ray bursts, each representing a different type and amount of energy release. This paper summarizes the properties of these explosions and describes new research on thermonuclear explosions and explosions in extended circumstellar media. Parallels are drawn between studies of terrestrial and astrophysical explosions, especially the physics of the transition from deflagration-to-detonation. PMID:22213668

  11. High Energy Neutrinos and Cosmic-Rays From Low-Luminosity Gamma-Ray Bursts?

    SciTech Connect

    Murase, Kohta; Ioka, Kunihito; Nagataki, Shigehiro; Nakamura, Takashi; /Kyoto U.

    2006-07-10

    The recently discovered gamma-ray burst (GRB) 060218/SN 2006aj is classified as an X-ray Flash with very long duration driven possibly by a neutron star. Since GRB 060218 is very near {approx} 140 Mpc and very dim, one-year observation by Swift suggests that the true rate of GRB 060218-like events might be very high so that such low luminosity GRBs (LL-GRBs) might form a different population of GRBs from the cosmological high luminosity GRBs (HL-GRBs). We found that the high energy neutrino background from such LL-GRBs could be comparable with or larger than that from HL-GRBs. If each neutrino event is detected by IceCube, later optical-infrared follow-up observations such as by Subaru could identify a Type Ibc supernova associated with LL-GRBs, even if gamma- and X-rays are not observed by Swift. This is in a sense a new window from neutrino astronomy, which might enable us to confirm the existence of LL-GRBs and to obtain information about their rate and origin. We also argue LL-GRBs as high energy gamma-ray and cosmic-ray sources.

  12. 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.

  13. 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.

  14. The Ulysses Supplement to the BATSE 4B Catalog of Cosmic Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Hurley, K.; Briggs, Michael S.; Kippen, Richard M.; Kouveliotou, Chryssa; Meegan, Charles A.; Fishman, Gerald J.; Cline, T. L.; Boer, M.

    1998-01-01

    We present Interplanetary Network Localization information for 150 gamma-ray bursts observed by the Burst and Transient Source Experiment(BATSE) between the end of the 3rd BATSE catalog and the end of the 4th 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 2.3 degrees, 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 25.

  15. Constraining cosmic reionization with quasar, gamma ray burst, and Lyalpha emitter observations

    NASA Astrophysics Data System (ADS)

    Gallerani, S.; Ferrara, A.; Choudhury, T. Roy; Fan, X.; Salvaterra, R.; Dayal, P.

    We investigate the cosmic reionization history by comparing semi-analytical models of the Lyalpha forest with observations of high-z quasars and gamma ray bursts absorption spectra. In order to constrain the reionization epoch z_rei, we consider two physically motivated scenarios in which reionization ends either early (ERM, z_reigtrsim 7) or late (LRM, z_rei≈ 6). We analyze the transmitted flux in a sample of 17 QSOs spectra at 5.7< z_em< 6.4 and in the spectrum of the GRB 050904 at z=6.3, studying the wide dark portions (gaps) in the observed absorption spectra. By comparing the statistics of these spectral features with our models, we conclude that current observational data do not require any sudden change in the ionization state of the IGM at z≈ 6, favouring indeed a highly ionized Universe at these epochs, as predicted by the ERM. Moreover, we test the predictions of this model through Lyalpha emitters observations, finding that the ERM provide a good fit to the evolution of the luminosity function of Lyalpha emitting galaxies in the redshift range z=5.7-6.5. The overall result points towards an extended reionization process which starts at zgtrsim 11 and completes at z_reigtrsim 7, in agreement with the recent WMAP5 data.

  16. On the binary nature of cosmic gamma-ray burst sources

    NASA Technical Reports Server (NTRS)

    Rappaport, S. A.; Joss, P. C.

    1985-01-01

    The binary model of gamma ray burst sources wherein the bursts are emitted by a collapsed object in a close-binary stellar system and a small fraction of the gamma radiation is reprocessed into optical radiation in the surface layers of a companion star is considered, and it is concluded that the model is viable. In particular, under the assumption that the optical flashes discovered by Schaefer (1981) and Schaefer et al. (1984) were produced by gamma-ray bursts of about the same intensity as those observed, it is found that nearby binary systems with secondaries whose masses are less than about 0.06 solar mass can fit all the observational constraints for the three optical/gamma-ray pair events.

  17. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BURST AND TRANSIENT SOURCE EXPERIMENT 5B CATALOG OF COSMIC GAMMA-RAY BURSTS

    SciTech Connect

    Hurley, K.; Briggs, M. S.; Kippen, R. M.; Kouveliotou, C.; Fishman, G.; Cline, T.; Trombka, J.; McClanahan, T.; Boynton, W.; Starr, R.; McNutt, R.; Boer, M.

    2011-09-01

    We present Interplanetary Network localization information for 343 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO spacecraft. For any given burst observed by CGRO and one other spacecraft, arrival time analysis (or 'triangulation') results in an annulus of possible arrival directions whose half-width varies between 11 arcsec and 21{sup 0}, depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the area of a factor of 20. When all three spacecraft observe a burst, the result is an error box whose area varies between 1 and 48,000 arcmin{sup 2}, resulting in an average reduction of the BATSE error circle area of a factor of 87.

  18. UHECR ESCAPE MECHANISMS FOR PROTONS AND NEUTRONS FROM GAMMA-RAY BURSTS, AND THE COSMIC-RAY-NEUTRINO CONNECTION

    SciTech Connect

    Baerwald, Philipp; Bustamante, Mauricio; Winter, Walter E-mail: mauricio.bustamante@physik.uni-wuerzburg.de

    2013-05-10

    The paradigm that gamma-ray burst fireballs are the sources of the ultra-high energy cosmic rays (UHECRs) is being probed by neutrino observations. Very stringent bounds can be obtained from the cosmic-ray (proton)-neutrino connection, assuming that the UHECRs escape as neutrons. In this study, we identify three different regimes as a function of the fireball parameters: the standard ''one neutrino per cosmic ray'' case, the optically thick (to neutron escape) case, and the case where leakage of protons from the boundaries of the shells (direct escape) dominates. In the optically thick regime, the photomeson production is very efficient, and more neutrinos will be emitted per cosmic ray than in the standard case, whereas in the direct escape-dominated regime, more cosmic rays than neutrinos will be emitted. We demonstrate that, for efficient proton acceleration, which is required to describe the observed UHECR spectrum, the standard case only applies to a very narrow region of the fireball parameter space. We illustrate with several observed examples that conclusions on the cosmic-ray-neutrino connection will depend on the actual burst parameters. We also show that the definition of the pion production efficiency currently used by the IceCube collaboration underestimates the neutrino production in the optically thick case. Finally, we point out that the direct escape component leads to a spectral break in the cosmic-ray spectrum emitted from a single source. The resulting ''two-component model'' can be used to even more strongly pronounce the spectral features of the observed UHECR spectrum than the dip model.

  19. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE FERMI GBM CATALOG OF COSMIC GAMMA-RAY BURSTS

    SciTech Connect

    Hurley, K.; Pal'shin, V. D.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Svinkin, D. S.; Briggs, M. S.; Connaughton, V.; Meegan, C.; Goldsten, J.; Boynton, W.; Fellows, C.; Harshman, K.; Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B.; and others

    2013-08-15

    We present Interplanetary Network (IPN) data for the gamma-ray bursts in the first Fermi Gamma-Ray Burst Monitor (GBM) catalog. Of the 491 bursts in that catalog, covering 2008 July 12 to 2010 July 11, 427 were observed by at least one other instrument in the nine-spacecraft IPN. Of the 427, the localizations of 149 could be improved by arrival time analysis (or {sup t}riangulation{sup )}. For any given burst observed by the GBM and one other distant spacecraft, triangulation gives an annulus of possible arrival directions whose half-width varies between about 0.'4 and 32 Degree-Sign , depending on the intensity, time history, and arrival direction of the burst, as well as the distance between the spacecraft. We find that the IPN localizations intersect the 1{sigma} GBM error circles in only 52% of the cases, if no systematic uncertainty is assumed for the latter. If a 6 Degree-Sign systematic uncertainty is assumed and added in quadrature, the two localization samples agree about 87% of the time, as would be expected. If we then multiply the resulting error radii by a factor of three, the two samples agree in slightly over 98% of the cases, providing a good estimate of the GBM 3{sigma} error radius. The IPN 3{sigma} error boxes have areas between about 1 arcmin{sup 2} and 110 deg{sup 2}, and are, on the average, a factor of 180 smaller than the corresponding GBM localizations. We identify two bursts in the IPN/GBM sample that did not appear in the GBM catalog. In one case, the GBM triggered on a terrestrial gamma flash, and in the other, its origin was given as ''uncertain''. We also discuss the sensitivity and calibration of the IPN.

  20. BOOTES and GTC observations of cosmic gamma-ray bursts and their progenitors

    NASA Astrophysics Data System (ADS)

    Castro-Tirado, Alberto J.

    2016-07-01

    We will summarize the follow-up observations of gamma-ray bursts performed worldwide by the BOOTES Network of robotic telescopes (with some of the data being contemporaneous to the prompt emission) leading to the discovery of many afterglows. Complementary data has been also obtained by the 10.4m GTC telescope in La Palma (mainly spectroscopy), with one of them being the highest extinguished afterglow detected to date.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    The gamma-ray burst (GRB) rate is essential for revealing the connection between GRBs, supernovae and stellar evolution. Additionally, the long GRB rate at high redshift provides a strong probe of star formation history in the early universe. While hundreds of GRBs are observed by Swift, it remains difficult to determine the intrinsic GRB rate due to Swift’s complex trigger algorithm. Current studies usually approximate the Swift trigger algorithm by a single detection threshold. However, unlike the previously flown GRB instruments, Swift has over 500 trigger criteria based on photon count rate and additional image threshold for localization. To investigate possible systematic biases and explore the intrinsic GRB properties, we developed a program that is capable of simulating all the rate trigger criteria and mimicking the image trigger threshold. We use this program to search for the intrinsic GRB rate. Our simulations show that adopting the Swift’s complex trigger algorithm increases the detection rate of dim bursts. Therefore, GRBs need to be intrinsically dimmer than previously expected to avoid over-producing the number of detections and to match with Swift observations. As a result, we find that either the GRB rate is much higher at large redshift than previous expectations, or the luminosity evolution is non-negligible.

  2. Ultrahigh-energy cosmic ray production by turbulence in gamma-ray burst jets and cosmogenic neutrinos

    NASA Astrophysics Data System (ADS)

    Asano, Katsuaki; Mészáros, Peter

    2016-07-01

    We propose a novel model to produce ultrahigh-energy cosmic rays (UHECRs) in gamma-ray burst jets. After the prompt gamma-ray emission, hydrodynamical turbulence is excited in the GRB jets at or before the afterglow phase. The mildly relativistic turbulence stochastically accelerates protons. The acceleration rate is much slower than the usual first-order shock acceleration rate, but in this case it can be energy independent. The resultant UHECR spectrum is so hard that the bulk energy is concentrated in the highest energy range, resulting in a moderate requirement for the typical cosmic-ray luminosity of ˜1 053.5 erg s-1 . In this model, the secondary gamma-ray and neutrino emissions initiated by photopion production are significantly suppressed. Although the UHECR spectrum at injection shows a curved feature, this does not conflict with the observed UHECR spectral shape. The cosmogenic neutrino spectrum in the 1017- 1018 eV range becomes distinctively hard in this model, which may be verified by future observations.

  3. Aspects of the Spectral Evolution of Cosmic Gamma-Ray Bursts.

    NASA Astrophysics Data System (ADS)

    Ryde, elix

    2000-08-01

    Ever since their discovery at the end of the 1960s, the occasional, short flashes of gamma-rays, denoted gamma-ray bursts (GRBs), have been some of the most enigmatic phenomena to have been encountered in astrophysics. Large resources are being put into the quest to understand these objects and great progress has been made. In particular, during recent years it has become evident that GRBs lie at large, cosmological distances, which implies, from the measured energies, that they are the most powerful explosions in the Universe since its creation. They are detected approximately once per day and occur in an average galaxy probably once every 10 million years. This thesis discusses various aspects of the spectral and temporal behaviour of the gamma-ray emission in long and bright pulses of prompt GRBs. This is studied both by analytical derivations and through the study of data from the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma-Ray Observatory (CGRO) satellite. A self-consistent formulation of the spectral and temporal evolution during the decay of a GRB pulse is presented and explored. This leads to the finding that the decay of GRB pulses can be described by a particular power-law function and that there is a bimodality in the distribution of the associated power-law index. The importance of studying the temporally resolved spectra during a GRB, and especially during a pulse, is stressed. These spectra have a direct connection with the underlying emission process (possibly affected by relativistic effects due to the outflow emitting the gamma-rays). The time-integrated spectrum, on the other hand, reflects mainly the spectral evolution. Analytical results are given, which connect the properties of the time-integrated spectrum with those of the time-resolved spectra, and are thus useful when studying observed GRB pulse spectra. The correlation between the peak energy of the instantaneous spectrum (as a measure of spectral hardness) and

  4. Gravitational wave bursts from cosmic strings

    PubMed

    Damour; Vilenkin

    2000-10-30

    Cusps of cosmic strings emit strong beams of high-frequency gravitational waves (GW). As a consequence of these beams, the stochastic ensemble of gravitational waves generated by a cosmological network of oscillating loops is strongly non-Gaussian, and includes occasional sharp bursts that stand above the rms GW background. These bursts might be detectable by the planned GW detectors LIGO/VIRGO and LISA for string tensions as small as G&mgr; approximately 10(-13). The GW bursts discussed here might be accompanied by gamma ray bursts. PMID:11041921

  5. 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.

  6. Probing Cosmic Dust of the Early Universe through High-Redshift Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Liang, S. L.; Li, Aigen

    2009-01-01

    We explore the extinction properties of the dust in the distant universe through the afterglows of high-redshifted gamma-ray bursts (GRBs) based on the "Drude" model which, unlike previous studies, does not require a prior assumption of template extinction laws. We select GRB 070802 at z ≈ 2.45 (which shows clear evidence for the 2175 Å extinction bump) and GRB 050904 at z ≈ 6.29, the second most distant GRB observed to date. We fit their afterglow spectra to determine the extinction of their host galaxies. We find that (1) their extinction curves differ substantially from that of the Milky Way and the Small and Large Magellanic Clouds (which were widely adopted as template extinction laws in the literature); (2) the 2175 Å extinction feature appears to be also present in GRB 050904 at z ≈ 6.29; and (3) there does not appear to be strong evidence for the dependence of dust extinction on redshifts. The inferred extinction curves are closely reproduced in terms of a mixture of amorphous silicate and graphite, both of which are expected supernova condensates and have been identified in primitive meteorites as presolar grains originating from supernovae (which are considered as the main source of dust at high-z).

  7. Topics in Particle Astrophysics: Dark Matter, Gamma-Ray Bursts, and the Origin of Ultra-High-Energy Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Calvez, Antoine

    Since the first observation of cosmic rays in the early 1900's, intensive astronomical and cosmological observations, and improvements in particle detectors have generated important discoveries such as the existence of gamma-ray bursts and pulsars; they have also generated puzzling evidence for dark matter and dark energy, and for the existence of particles in the interstellar medium with energy beyond 1020 eV. In this dissertation, I will investigate some of the current theoretical challenges posed by the latest cosmological and astrophysical observations, and attempt to provide a unifying solution to the problems. X-ray and gamma-ray observations can help understand the origin of the electron and positron signals reported by ATIC, PAMELA, PPB-BETS , and Fermi. It remains unclear whether the observed high-energy electrons and positrons are produced by relic particles, or by astrophysical sources. To distinguish between the two possibilities, one can compare the electron population in the local neighborhood with that in Dwarf Spheroidal Galaxies (dSphs), which are not expected to host as many gamma-ray bursts, pulsars, or other astrophysical sources. This can be accomplished using X-ray and gamma-ray observations. Assuming the signal detected by Fermi and ATIC comes from dark matter, we calculate the photon spectrum produced by electrons via inverse Compton scattering with the Cosmic Microwave Background radiation (CMB). Since little is known about the magnetic fields in dwarf spheroidals, we consider the propagation of charged particles with and without diffusion. Extending the analysis of the Fermi collaboration for the Draco dwarf spheroidal galaxy, we find that even in the absence of diffusion, the expected gamma-ray signal lies above the upper limits set by the Fermi telescope, thus favoring astrophysical sources such as gamma-ray bursts and pulsars. Furthermore, if one assumes that a local magnetic field exists in the dwarf spheroidal galaxy, the diffusion of

  8. CONNECTING THE GAMMA RAY BURST RATE AND THE COSMIC STAR FORMATION HISTORY: IMPLICATIONS FOR REIONIZATION AND GALAXY EVOLUTION

    SciTech Connect

    Robertson, Brant E.; Ellis, Richard S.

    2012-01-10

    The contemporary discoveries of galaxies and gamma ray bursts (GRBs) at high redshift have supplied the first direct information on star formation when the universe was only a few hundred million years old. The probable origin of long duration GRBs in the deaths of massive stars would link the universal GRB rate to the redshift-dependent star formation rate (SFR) density, although exactly how is currently unknown. As the most distant GRBs and star-forming galaxies probe the reionization epoch, the potential reward of understanding the redshift-dependent ratio {Psi}(z) of the GRB rate to SFR is significant and includes addressing fundamental questions such as incompleteness in rest-frame UV surveys for determining the SFR at high redshift and time variations in the stellar initial mass function. Using an extensive sample of 112 GRBs above a fixed luminosity limit drawn from the Second Swift Burst Alert Telescope catalog and accounting for uncertainty in their redshift distribution by considering the contribution of 'dark' GRBs, we compare the cumulative redshift distribution N(< z) of GRBs with the star formation density {rho}-dot{sub *}(z) measured from UV-selected galaxies over 0 < z <4. Strong evolution (e.g., {Psi}(z){proportional_to}(1 + z){sup 1.5}) is disfavored (Kolmogorov-Smirnov test P < 0.07). We show that more modest evolution (e.g., {Psi}(z){proportional_to}(1 + z){sup 0.5}) is consistent with the data (P Almost-Equal-To 0.9) and can be readily explained if GRBs occur primarily in low-metallicity galaxies which are proportionally more numerous at earlier times. If such trends continue beyond z {approx_equal} 4, we find that the discovery rate of distant GRBs implies an SFR density much higher than that inferred from UV-selected galaxies. While some previous studies of the GRB-SFR connection have concluded that GRB-inferred star formation at high redshift would be sufficient to maintain cosmic reionization over 6

  9. Neutrino, Neutron, and Cosmic-Ray Production in the External Shock Model of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Dermer, Charles D.

    2002-07-01

    The hypothesis that ultrahigh-energy (>~1019 eV) cosmic rays (UHECRs) are accelerated by gamma-ray burst (GRB) blast waves is assumed to be correct. Implications of this assumption are then derived for the external shock model of GRBs. The evolving synchrotron radiation spectrum in GRB blast waves provides target photons for the photomeson production of neutrinos and neutrons. Decay characteristics and radiative efficiencies of the neutral particles that escape from the blast wave are calculated. The diffuse high-energy GRB neutrino background and the distribution of high-energy GRB neutrino events are calculated for specific parameter sets, and a scaling relation for the photomeson production efficiency in surroundings with different densities is derived. GRBs provide an intense flux of high-energy neutrons, with neutron production efficiencies exceeding ~1% of the total energy release. The radiative characteristics of the neutron β-decay electrons from the GRB ``neutron bomb'' are solved in a special case. Galaxies with GRB activity should be surrounded by radiation halos of ~100 kpc extent from the outflowing neutrons, consisting of a nonthermal optical/X-ray synchrotron component and a high-energy gamma-ray component from Compton-scattered microwave background radiation. The peak luminosity emitted by the diffuse β electron halo from a single GRB with >~2×1053 ergs isotropic energy release is ~1035 ergs s-1, with a potentially much brighter signal from the neutron decay protons. The decay halo from a single GRB can persist for >~0.1-1 Myr. Stronger neutrino fluxes and neutron decay halos can be produced by external shocks in clumpy external media and in scenarios involving internal shock scenarios, so detection of neutrinos associated with smooth profile GRBs could rule out an impulsive GRB central engine and an external shock model for the prompt phase. The luminosity of sources of GRBs and relativistic outflows in L* galaxies such as the Milky Way is at

  10. 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.

  11. Spectral measurements of cosmic gamma-ray bursts with the Konus-Wind and Konus-A instruments

    SciTech Connect

    Golenetskii, S. V.; Aptekar, R. L.; Frederiks, D. D.; Il'inskii, V. N.; Mazets, E. P.; Panov, V. N.; Sokolova, Z. J.; Terekhov, M. M.

    1998-05-16

    The Konus gamma-ray burst instrumentation on board the US GGS-Wind spacecraft and the near-Earth Russian satellite Kosmos-2326 makes it possible to make spectral measurements and comparisons between 12 keV to 10 MeV. Since November 1994, over 370 bursts have been observed in the triggered mode, for which detailed spectral measurements are available. Incident photon spectra are derived from the count rate spectra of a number of bright bursts for which the celestial source position or the angle relative to the sensor axis is known. The spectral evolution of these bursts and the possible existence of spectral features in both the soft and hard energy bands are discussed.

  12. GAMMA-RAY BURST HOST GALAXY SURVEYS AT REDSHIFT z {approx}> 4: PROBES OF STAR FORMATION RATE AND COSMIC REIONIZATION

    SciTech Connect

    Trenti, Michele; Perna, Rosalba; Levesque, Emily M.; Shull, J. Michael; Stocke, John T.

    2012-04-20

    Measuring the star formation rate (SFR) at high redshift is crucial for understanding cosmic reionization and galaxy formation. Two common complementary approaches are Lyman break galaxy (LBG) surveys for large samples and gamma-ray burst (GRB) observations for sensitivity to SFR in small galaxies. The z {approx}> 4 GRB-inferred SFR is higher than the LBG rate, but this difference is difficult to understand, as both methods rely on several modeling assumptions. Using a physically motivated galaxy luminosity function model, with star formation in dark matter halos with virial temperature T{sub vir} {approx}> 2 Multiplication-Sign 10{sup 4} K (M{sub DM} {approx}> 2 Multiplication-Sign 10{sup 8} M{sub Sun }), we show that GRB- and LBG-derived SFRs are consistent if GRBs extend to faint galaxies (M{sub AB} {approx}< -11). To test star formation below the detection limit L{sub lim} {approx} 0.05L*{sub z=3} of LBG surveys, we propose to measure the fraction f{sub det}(L > L{sub lim}, z) of GRB hosts with L > L{sub lim}. This fraction quantifies the missing star formation fraction in LBG surveys, constraining the mass-suppression scale for galaxy formation, with weak dependence on modeling assumptions. Because f{sub det}(L > L{sub lim}, z) corresponds to the ratio of SFRs derived from LBG and GRB surveys, if these estimators are unbiased, measuring f{sub det}(L > L{sub lim}, z) also constrains the redshift evolution of the GRB production rate per unit mass of star formation. Our analysis predicts significant success for GRB host detections at z {approx} 5 with f{sub det}(L > L{sub lim}, z) {approx} 0.4, but rarer detections at z > 6. By analyzing the upper limits on host galaxy luminosities of six z > 5 GRBs from literature data, we infer that galaxies with M{sub AB} > -15 were present at z > 5 at 95% confidence, demonstrating the key role played by very faint galaxies during reionization.

  13. Gamma-ray bursts.

    PubMed

    Gehrels, Neil; Mészáros, Péter

    2012-08-24

    Gamma-ray bursts (GRBs) are bright flashes of gamma rays coming from the cosmos. They occur roughly once per day, typically last for tens 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 afterglow. PMID:22923573

  14. 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.

  15. Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Gehrels, Neil; Mészáros, Péter

    2012-08-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma rays coming from the cosmos. They occur roughly once per day, typically last for tens 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 afterglow.

  16. High-energy cosmic-ray nuclei from high- and low-luminosity gamma-ray bursts and implications for multimessenger astronomy

    SciTech Connect

    Murase, Kohta; Nagataki, Shigehiro; Ioka, Kunihito; Nakamura, Takashi

    2008-07-15

    Gamma-ray bursts (GRBs) are one of the candidates of ultrahigh-energy (> or approx. 10{sup 18.5} eV) cosmic-ray (UHECR) sources. We investigate high-energy cosmic-ray acceleration including heavy nuclei in GRBs by using Geant 4, and discuss its various implications, taking both high-luminosity (HL) and low-luminosity (LL) GRBs into account. This is because LL GRBs may also make a significant contribution to the observed UHECR flux if they form a distinct population. We show that not only protons, but also heavier nuclei can be accelerated up to ultrahigh energies in the internal, (external) reverse, and forward shock models. We also show that the condition for ultrahigh-energy heavy nuclei such as iron to survive is almost the same as that for {approx}TeV gamma rays to escape from the source and for high-energy neutrinos not to be much produced. The multimessenger astronomy by neutrino and GeV-TeV gamma-ray telescopes such as IceCube and KM3Net, GLAST and MAGIC will be important to see whether GRBs can be accelerators of ultrahigh-energy heavy nuclei. We also demonstrate expected spectra of high-energy neutrinos and gamma rays, and discuss their detectabilities. In addition, we discuss implications of the GRB-UHECR hypothesis. We point out, since the number densities of HL GRBs and LL GRBs are quite different, its determination by UHECR observations is also important.

  17. 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.

  18. Spectral evolution in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Norris, J. P.; Share, G. H.; Messina, D. C.; Matz, M.; Kouveliotou, C.; Dennis, B. R.; Desai, U. D.; Cline, T. L.

    1986-01-01

    The Hard X-ray Burst Spectrometer (HXRBS) and the Gamma-Ray Spectrometer (GRS) on NASA's Solar Maximum Mission satellite have independently monitored cosmic gamma-ray bursts since launch in February 1980. Several bursts with relatively simple pulse structure and sufficient intensity have been analyzed for evidence of spectral variability on time scales shorter than the pulse durations. In many of these bursts pulse structures are found, ranging in duration from 1 to 10 seconds, which exhibit a trend of hard-to-soft spectral evolution. No significant evidence for soft-to-hard evolution has been found. The HXRBS data above 100 keV and the GRS data above 1 MeV indicate that the spectral evolution generally is not due to time-varying absorption features at energies below 100 keV.

  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. Swift's 500th Gamma Ray Burst

    NASA Video Gallery

    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...

  1. Cosmological gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Paczynski, Bohdan

    1991-01-01

    The distribution in angle and flux of gamma-ray bursts indicates that the majority of gamma-ray bursters are at cosmological distances, i.e., at z of about 1. The rate is then about 10 exp -8/yr in a galaxy like the Milky Way, i.e., orders of magnitude lower than the estimated rate for collisions between neutron stars in close binary systems. The energy per burst is about 10 exp 51 ergs, assuming isotropic emission. The events appear to be less energetic and more frequent if their emission is strongly beamed. Some tests for the distance scale are discussed: a correlation between the burst's strength and its spectrum; the absorption by the Galactic gas below about 2 keV; the X-ray tails caused by forward scattering by the Galactic dust; about 1 month recurrence of some bursts caused by gravitational lensing by foreground galaxies; and a search for gamma-ray bursts in M31. The bursts appear to be a manifestation of something exotic, but conventional compact objects can provide an explanation. The best possibility is offered by a decay of a bindary composed of a spinning-stellar-mass black-hole primary and a neutron or a strange-quark star secondary. In the final phase the secondary is tidally disrupted, forms an accretion disk, and up to 10 exp 54 ergs are released. A very small fraction of this energy powers the gamma-ray burst.

  2. 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.

  3. Gamma-ray burst models.

    PubMed

    King, Andrew

    2007-05-15

    I consider various possibilities for making gamma-ray bursts, particularly from close binaries. In addition to the much-studied neutron star+neutron star and black hole+neutron star cases usually considered good candidates for short-duration bursts, there are also other possibilities. In particular, neutron star+massive white dwarf has several desirable features. These systems are likely to produce long-duration gamma-ray bursts (GRBs), in some cases definitely without an accompanying supernova, as observed recently. This class of burst would have a strong correlation with star formation and occur close to the host galaxy. However, rare members of the class need not be near star-forming regions and could have any type of host galaxy. Thus, a long-duration burst far from any star-forming region would also be a signature of this class. Estimates based on the existence of a known progenitor suggest that this type of GRB may be quite common, in agreement with the fact that the absence of a supernova can only be established in nearby bursts. PMID:17293332

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Gamma-ray burst observations by Pioneer Venus Orbiter

    NASA Technical Reports Server (NTRS)

    Evans, W. D.; Glore, J. P.; Klebesadel, R. W.; Laros, J. G.; Tech, E. R.; Spalding, R. E.

    1979-01-01

    The Pioneer Venus Orbiter gamma burst detector is an astrophysics experiment for monitoring cosmic gamma-ray bursts. It is included in this planetary mission to provide a long baseline for accurately locating the sources of these bursts in order to identify them with specific astronomical objects. Responses to 14 gamma-ray burst events were examined; these events were verified from data acquired by other systems. Preliminary locations are proposed for three events, based on data from the Pioneer Venus Orbiter, ISEE C, and Vela spacecraft. These locations will be improved, and additional locations will be determined by including in the analyses data from Helios B and the Russian Venera 11, Venera 12, and Prognoz 7 spacecraft.

  9. Goddard contributions to the Los Alamos Conference on Transient Cosmic Gamma and X-ray Sources

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Conference papers, covering the orgin and instrumentation for measuring the position of cosmic gamma ray bursts, are presented. Summaries cover gamma ray detectors, energy speectra, and the stellar super flare hypothesis.

  10. 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.

  11. Do gamma-ray burst sources repeat?

    NASA Technical Reports Server (NTRS)

    Meegan, C. A.; Hartmann, D. H.; Brainerd, J. J.; Briggs, M.; Paciesas, W. S.; Pendleton, G.; Kouveliotou, C.; Fishman, G.; Blumenthal, G.; Brock, M.

    1994-01-01

    The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports 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 ad 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 bursts cannot be excluded.

  12. Gamma-Ray Bursts: The End Game

    NASA Astrophysics Data System (ADS)

    Lamb, Don

    1997-11-01

    The nature of gamma-ray bursts has been one of the greatest unsolved mysteries in astrophysics for more than a quarter century. A major reason for this is that no definite counterparts to the bursts could be found at other wavelengths, despite intense efforts spanning more than two decades. Consequently, the study of gamma-ray bursts has been isolated from the rest of astronomy. Scientists studying them have had only the laws of physics and the bursts themselves to guide them in attempting to solve the burst mystery. All of this changed dramatically with the discovery earlier this year of fading X-ray and optical sources in the arcminute-sized positional error boxes of several gamma-ray bursts. For the first time, temporal, as well as spatial, coincidence could be used to associate these X-ray and optical sources with the gamma-ray bursts. As a result, the odds are great that the fading X-ray and optical sources are counterparts of the bursts, and that the study of gamma-ray bursts has finally been connected with the rest of astronomy. In this talk, we describe the dramatic new information about the nature of gamma-ray bursts that the X-ray, optical, and radio observations of the fading sources have provided, and emphasize the implications that this information has for the distance scale to the bursts.

  13. 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

  14. Emission model of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Liang, E. P.

    1983-01-01

    The emission mechanisms of cosmic gamma-ray bursts are reviewed. In particular, the thermal synchrotron model is discussed as the most viable mechanism for the majority of the continuum emission. Within this framework various information about the source region can be extracted. The picture that emerges is that of a hot (kT = .2 - 1.0 sq mc), thin sheet of dense pair-dominated plasma emitting via cyclo-synchrotron radiation in a strong magnetic field (B approximately one-hundred billion to one trillion gauss). Speculations on the origin and structure of this sheet are attempted. The problem of high-energy photons above pair production threshold escaping from the source is also considered.

  15. 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.

  16. Search for Short Bursts of Gamma Rays with SGARFACE

    NASA Astrophysics Data System (ADS)

    Schroedter, M.; Manseri, H.; LeBohec, S.; Krennrich, F.; Downdall, C.; Falcone, A.; Fegan, S.; Horan, D.; Smith, A.; Toner, J.; Weekes, T.

    The Short GAmma Ray Front Air Cherenkov Experiment is designed to search for bursts of gamma rays above 200 MeV lasting from 60 nanoseconds to longer than 20 microseconds. The custom-designed trigger and data-acquisition system of SGARFACE piggy-backs on the existing Whipple 10m telescope. The experiment has operated for more than 3 years during which time about 1.2 million events were recorded. The majority of events originate from cosmic-ray showers from which we see, both, Cherenkov emission and fluorescence light. Rejection of background events is achieved through timing and imaging information available for each event. Potential sources of bursts of gamma rays are evaporation of primordial black holes within about 240 pc and gamma-ray emission accompanying giant radio pulses. Results are presented on the search for evaporation of primordial black holes and gamma-ray emission coincident with giant pulses from the Crab Nebula.

  17. Optical search for gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Ceplecha, Z.; Ehrlich, J.; Borovicka, J.; Hurley, K.; Ateia, J.-L.; Barat, C.; Niel, M.; Vedrenne, G.; Estulin, I. V.

    Preliminary results from an optical search for light pulses associated with gamma-ray bursts by means of the Czechoslovak Fireball Network plate collection at the Ondřejov Observatory are given. Optical monitoring represents more than 7700 hours, but no real optical counterpart was found. Problems associated with the optical search for gamma-ray bursts are discussed.

  18. Ballerina - pirouettes in search of gamma bursts

    NASA Astrophysics Data System (ADS)

    Brandt, S.; Lund, N.; Pedersen, H.; Hjorth, J.; BALLERINA Collaboration

    1999-09-01

    The cosmological origin of gamma ray bursts has now been established with reasonable certainty. Many more bursts will need to be studied to establish the typical distance scale, and to map out the large diversity in properties which have been indicated by the first handful of events. We are proposing Ballerina, a small satellite to provide accurate positions and new data on the gamma-ray bursts. We anticipate a detection rate an order of magnitude larger than obtained from Beppo-SAX.

  19. Comets, X-ray bursts, and gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Katz, J. I.

    1986-01-01

    The proposal, revived by Tremaine and Zytkow (1985), that accretion of comets by neutron stars may be the origin of gamma-ray bursts is considered. This mechanism has difficulty accounting for the observed gamma-ray spectrum and optical counterparts of the bursts. The survival of comets near supernovae is investigated. Ablation rates and the thermal structure of an ablating surface layer are calculated. In some circumstances, mechanical disruption will erode a comet more rapidly than evaporation. The accretion of comets by neutron stars may produce a class of X-ray burst sources with novel properties.

  20. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE BeppoSAX GAMMA-RAY BURST CATALOGS

    SciTech Connect

    Hurley, K.; Guidorzi, C.; Frontera, F.; Montanari, E.; Rossi, F.; Feroci, M.; Mazets, E.; Golenetskii, S.; Frederiks, D. D.; Pal'shin, V. D.; Aptekar, R. L.; Cline, T.; Trombka, J.; McClanahan, T.; Starr, R.; Atteia, J.-L.; Barraud, C.; Pelangeon, A.; Boer, M.; Vanderspek, R.

    2010-11-15

    Between 1996 July and 2002 April, one or more spacecraft of the interplanetary network detected 786 cosmic gamma-ray bursts that were also detected by the Gamma-Ray Burst Monitor and/or Wide-Field X-Ray Camera experiments aboard the BeppoSAX spacecraft. During this period, the network consisted of up to six spacecraft, and using triangulation, the localizations of 475 bursts were obtained. We present the localization data for these events.

  1. Cloaked Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Eichler, David

    2014-06-01

    It is suggested that many gamma-ray bursts (GRBs) are cloaked by an ultrarelativistic baryonic shell that has high optical depth when the photons are manufactured. Such a shell would not fully block photons reflected or emitted from its inner surface, because the radial velocity of the photons can be less than that of the shell. This avoids the standard problem associated with GRBs that the thermal component should be produced where the flow is still obscured by high optical depth. The radiation that escapes high optical depth obeys the Amati relation. Observational implications may include (1) anomalously high ratios of afterglow to prompt emission, such as may have been the case in the recently discovered PTF 11agg, and (2) ultrahigh-energy neutrino pulses that are non-coincident with detectable GRB. It is suggested that GRB 090510, a short, very hard GRB with very little afterglow, was an exposed GRB, in contrast to those cloaked by baryonic shells.

  2. CLOAKED GAMMA-RAY BURSTS

    SciTech Connect

    Eichler, David

    2014-06-01

    It is suggested that many gamma-ray bursts (GRBs) are cloaked by an ultrarelativistic baryonic shell that has high optical depth when the photons are manufactured. Such a shell would not fully block photons reflected or emitted from its inner surface, because the radial velocity of the photons can be less than that of the shell. This avoids the standard problem associated with GRBs that the thermal component should be produced where the flow is still obscured by high optical depth. The radiation that escapes high optical depth obeys the Amati relation. Observational implications may include (1) anomalously high ratios of afterglow to prompt emission, such as may have been the case in the recently discovered PTF 11agg, and (2) ultrahigh-energy neutrino pulses that are non-coincident with detectable GRB. It is suggested that GRB 090510, a short, very hard GRB with very little afterglow, was an exposed GRB, in contrast to those cloaked by baryonic shells.

  3. 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.

  4. Statistics of cosmological gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Dermer, Charles D.

    1992-01-01

    A phenomenological model of gamma-ray burst spectra is used to calculate the statistics of gamma-ray bursts originating at cosmological distances. A model of bursters with no source evolution in a q sub 0 = 1/2 Friedmann cosmology is in accord with recent observations of the differential V/Vmax distribution. The data are best fit with an average peak-burst luminosity of (4 +/- 2) x 10 exp 51 ergs/s and a present-day source emissivity of 940 +/- 440 bursts/(10 exp 10 yr) cu Mpc. A spectral test of the cosmological hypothesis is proposed.

  5. 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.

  6. Gamma-Ray Bursts: An Overview

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    1995-01-01

    A history and overview of the observed properties of gamma-ray bursts are presented. The phenomenon of gamma-ray bursts is without precedent in astronomy, having no observed property that would be a direct indicator of their distance and no counterpart object in another wavelength region. Their brief, random appearance only in the gamma-ray region has made their study difficult. The observed time profiles, spectral properties, and durations of gamma-ray bursts cover a wide range. All proposed models for their origin must be considered speculative. It is humbling to think that even after 25 years since their discovery, the distance scale of gamma-ray bursts is still very much debatable.

  7. The history of gamma-ray burst observations

    SciTech Connect

    Klebesadel, R.W.

    1988-01-01

    Cosmic gamma-ray bursts have been observed for 1-1/2 decades since their fortuitous discovery by nuclear test detection instruments flown on the Vela satellites. Although the volume and detail of data available through these observations has considerably refined our knowledge of the characteristics of these events, there is no confident identification of source objects or reliable model of the processes involved. The observations do suggest, however, that the bursts originate at neutron stars (probably highly-magnetized neutron stars). 17 refs., 16 figs.

  8. 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.

  9. ADP study of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Lamb, Don Q.; Wang, John C. L.; Heuter, Geoffry J.; Graziani, Carlo; Loredo, Tom; Freeman, Peter

    This grant supported study of cyclotron scattering lines in the spectra of gamma-ray bursts through analysis of Ginga and HEAO-1 archival data, and modeling of the results in terms of radiation transfer calculations of cyclotron scattering in a strong magnetic field. A Monte Carlo radiation transfer code with which we are able to calculate the expected properties of cyclotron scattering lines in the spectra of gamma-ray bursts was developed. The extensive software necessary in order to carry out fits of these model spectra to gamma-ray burst spectral data, including folding of the model spectra through the detector response functions was also developed. Fits to Ginga satellite data on burst GB880205 were completed and fits to Ginga satellite data on burst GB870303 are being carried out. These fits have allowed us to test our software, as well as to garner new scientific results. This work has demonstrated that cyclotron resonant scattering successfully accounts for the locations, strengths, and widths of the observed line features in GB870303 and GB880205. The success of the model provides compelling evidence that these gamma-ray bursts come from strongly magnetic neutron stars and are galactic in origin, resolving longstanding controversies about the nature and distance of the burst sources. These results were reported in two papers which are in press in the proceedings of the Taos Workshop on Gamma-Ray Bursts, and in a paper submitted for publication.

  10. ADP study of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Lamb, Don Q.; Wang, John C. L.; Heuter, Geoffry J.; Graziani, Carlo; Loredo, Tom; Freeman, Peter

    1991-01-01

    This grant supported study of cyclotron scattering lines in the spectra of gamma-ray bursts through analysis of Ginga and HEAO-1 archival data, and modeling of the results in terms of radiation transfer calculations of cyclotron scattering in a strong magnetic field. A Monte Carlo radiation transfer code with which we are able to calculate the expected properties of cyclotron scattering lines in the spectra of gamma-ray bursts was developed. The extensive software necessary in order to carry out fits of these model spectra to gamma-ray burst spectral data, including folding of the model spectra through the detector response functions was also developed. Fits to Ginga satellite data on burst GB880205 were completed and fits to Ginga satellite data on burst GB870303 are being carried out. These fits have allowed us to test our software, as well as to garner new scientific results. This work has demonstrated that cyclotron resonant scattering successfully accounts for the locations, strengths, and widths of the observed line features in GB870303 and GB880205. The success of the model provides compelling evidence that these gamma-ray bursts come from strongly magnetic neutron stars and are galactic in origin, resolving longstanding controversies about the nature and distance of the burst sources. These results were reported in two papers which are in press in the proceedings of the Taos Workshop on Gamma-Ray Bursts, and in a paper submitted for publication.

  11. 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. PMID:23630371

  12. 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.

  13. Gamma and Beta Bursts Underlie Working Memory.

    PubMed

    Lundqvist, Mikael; Rose, Jonas; Herman, Pawel; Brincat, Scott L; Buschman, Timothy J; Miller, Earl K

    2016-04-01

    Working memory is thought to result from sustained neuron spiking. However, computational models suggest complex dynamics with discrete oscillatory bursts. We analyzed local field potential (LFP) and spiking from the prefrontal cortex (PFC) of monkeys performing a working memory task. There were brief bursts of narrow-band gamma oscillations (45-100 Hz), varied in time and frequency, accompanying encoding and re-activation of sensory information. They appeared at a minority of recording sites associated with spiking reflecting the to-be-remembered items. Beta oscillations (20-35 Hz) also occurred in brief, variable bursts but reflected a default state interrupted by encoding and decoding. Only activity of neurons reflecting encoding/decoding correlated with changes in gamma burst rate. Thus, gamma bursts could gate access to, and prevent sensory interference with, working memory. This supports the hypothesis that working memory is manifested by discrete oscillatory dynamics and spiking, not sustained activity. PMID:26996084

  14. Overview Animation of Gamma-ray Burst

    NASA Video Gallery

    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...

  15. 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.

  16. 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.

  17. 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.

  18. 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%.

  19. Supernovae and gamma-ray bursts connection

    NASA Astrophysics Data System (ADS)

    Valle, Massimo Della

    2015-12-01

    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%.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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. .

  5. 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

  6. Implications of fast radio bursts for superconducting cosmic strings

    SciTech Connect

    Yu, Yun-Wei; Cheng, Kwong-Sang; Shiu, Gary; Tye, Henry E-mail: hrspksc@hku.hk E-mail: iastye@ust.hk

    2014-11-01

    Highly beamed, short-duration electromagnetic bursts could be produced by superconducting cosmic string (SCS) loops oscillating in cosmic magnetic fields. We demonstrated that the basic characteristics of SCS bursts such as the electromagnetic frequency and the energy release could be consistently exhibited in the recently discovered fast radio bursts (FRBs). Moreover, it is first showed that the redshift distribution of the FRBs can also be well accounted for by the SCS burst model. Such agreements between the FRBs and SCS bursts suggest that the FRBs could originate from SCS bursts and thus they could provide an effective probe to study SCSs. The obtained values of model parameters indicate that the loops generating the FRBs have a small length scale and they are mostly formed in the radiation-dominated cosmological epoch.

  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. THE INTERPLANETARY NETWORK SUPPLEMENT TO THE HETE-2 GAMMA-RAY BURST CATALOG

    SciTech Connect

    Hurley, K.; Atteia, J.-L.; Barraud, C.; Pelangeon, A.; Boeer, M.; Vanderspek, R.; Ricker, G.; Mazets, E.; Golenetskii, S.; Frederiks, D. D.; Pal'shin, V. D.; Aptekar, R. L.; Smith, D. M.; Wigger, C.; Hajdas, W.; Rau, A.; Von Kienlin, A.; Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S. [Space Research Institute, 84 and others

    2011-12-01

    Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also detected by the French Gamma-Ray Telescope experiment on board the High Energy Transient Experiment 2 spacecraft. During this period, the IPN consisted of up to nine spacecraft, and using triangulation, the localizations of 157 bursts were obtained. We present the IPN localization data on these events.

  9. The Gamma-ray Large Area Space Telescope and Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    McEnery, Julie; Ritz, Steve

    2006-01-01

    The Gamma-ray Large Area Telescope (GLAST) is a satellite-based observatory to study the high energy gamma-ray sky. The main instrument on GLAST, the Large Area Telescope (LAT) is a pair-conversion telescope that will survey the sky from 20 MeV to greater than 300 GeV. With the GLAST launch in 2007, the LAT will open a new and important window on a wide variety of high energy phenomena, including supermassive black holes and active galactic nuclei, gamma-ray bursts, supernova remnants and cosmic ray acceleration and dark matter. A second instrument, the GLAST Burst Monitor (GBM), greatly enhances GLAST s capability to study GRB by providing important spectral and timing information in the 10 keV to 30 MeV range. We describe how the instruments, spacecraft and ground system work together to provide observations of gamma-ray bursts from 8 keV - 300 GeV and to provide rapid notification of bursts to the wider gamma-ray burst community.

  10. 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

  11. Properties of multiple event gamma ray bursts

    SciTech Connect

    Lochner, J.C.

    1991-01-01

    We present results from a study of 37 multiple event gamma ray bursts found in the monitoring data of the PVO gamma ray burst detector. We define these bursts as those which have two or more distinct emission events separated by a return to the background intensity. Significant correlation exists between the duration of the first event and the duration of the second event, while some correlation exists between the hardness of the events and only weak correlation exists in the intensity of the events. Although the time profiles of events in a burst may be similar, as measured in the phase portrait, there is no general rule about the degree of similarity of the time profiles. Subdividing the data according to the recurrence time, we find a tendency for the strength of the correlation in the hardness to increase with decreasing separation between the events. 2 refs., 2 figs., 1 tab.

  12. Properties of multiple event gamma ray bursts

    SciTech Connect

    Lochner, J.C.

    1991-12-31

    We present results from a study of 37 multiple event gamma ray bursts found in the monitoring data of the PVO gamma ray burst detector. We define these bursts as those which have two or more distinct emission events separated by a return to the background intensity. Significant correlation exists between the duration of the first event and the duration of the second event, while some correlation exists between the hardness of the events and only weak correlation exists in the intensity of the events. Although the time profiles of events in a burst may be similar, as measured in the phase portrait, there is no general rule about the degree of similarity of the time profiles. Subdividing the data according to the recurrence time, we find a tendency for the strength of the correlation in the hardness to increase with decreasing separation between the events. 2 refs., 2 figs., 1 tab.

  13. 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.

  14. A population of massive, luminous galaxies hosting heavily dust-obscured gamma-ray bursts: Implications for the use of GRBs as tracers of cosmic star formation

    SciTech Connect

    Perley, D. A.; Levan, A. J.; Tanvir, N. R.; Cenko, S. B.; Bloom, J. S.; Filippenko, A. V.; Morgan, A. N.; Hjorth, J.; Krühler, T.; Fynbo, J. P. U.; Milvang-Jensen, B.; Fruchter, A.; Kalirai, J.; Jakobsson, P.; Prochaska, J. X.

    2013-12-01

    We present observations and analysis of the host galaxies of 23 heavily dust-obscured gamma-ray bursts (GRBs) observed by the Swift satellite during the years 2005-2009, representing all GRBs with an unambiguous host-frame extinction of A{sub V} > 1 mag from this period. Deep observations with Keck, Gemini, Very Large Telescope, Hubble Space Telescope, and Spitzer successfully detect the host galaxies and establish spectroscopic or photometric redshifts for all 23 events, enabling us to provide measurements of the intrinsic host star formation rates, stellar masses, and mean extinctions. Compared to the hosts of unobscured GRBs at similar redshifts, we find that the hosts of dust-obscured GRBs are (on average) more massive by about an order of magnitude and also more rapidly star forming and dust obscured. While this demonstrates that GRBs populate all types of star-forming galaxies, including the most massive, luminous systems at z ≈ 2, at redshifts below 1.5 the overall GRB population continues to show a highly significant aversion to massive galaxies and a preference for low-mass systems relative to what would be expected given a purely star-formation-rate-selected galaxy sample. This supports the notion that the GRB rate is strongly dependent on metallicity, and may suggest that the most massive galaxies in the universe underwent a transition in their chemical properties ∼9 Gyr ago. We also conclude that, based on the absence of unobscured GRBs in massive galaxies and the absence of obscured GRBs in low-mass galaxies, the dust distributions of the lowest-mass and the highest-mass galaxies are relatively homogeneous, while intermediate-mass galaxies (∼10{sup 9} M {sub ☉}) have diverse internal properties.

  15. Observations of short gamma-ray bursts.

    PubMed

    Fox, Derek B; Roming, Peter W A

    2007-05-15

    We review recent observations of short-hard gamma-ray bursts and their afterglows. The launch and successful ongoing operations of the Swift satellite, along with several localizations from the High-Energy Transient Explorer mission, have provoked a revolution in short-burst studies: first, by quickly providing high-quality positions to observers; and second, via rapid and sustained observations from the Swift satellite itself. We make a complete accounting of Swift-era short-burst localizations and proposed host galaxies, and discuss the implications of these observations for the distances, energetics and environments of short bursts, and the nature of their progenitors. We then review the physical modelling of short-burst afterglows: while the simplest afterglow models are inadequate to explain the observations, there have been several notable successes. Finally, we address the case of an unusual burst that threatens to upset the simple picture in which long bursts are due to the deaths of massive stars, and short bursts to compact-object merger events. PMID:17293336

  16. 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.

  17. 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.

  18. 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.

  19. Gamma-Ray Burst Progenitors: Merger Model

    NASA Astrophysics Data System (ADS)

    Ruffert, Maximilian

    2002-04-01

    The mergers of neutron stars and black holes remain a viable model for gamma-ray burst central engines, at least for the class of short bursts: their time scales, occurrence rates and energy output seem to be consistent with observations. We will present results of our latest simulations showing how the orbit of a neutron star around a black hole shrinks due to gravitational radiation, how the neutron star's matter gets accreted by the black hole, and how the tidal forces of the black hole finally shred the neutron star into a thick disk. In this process, huge amounts of energy are radiated away by gravitational waves and by neutrinos emitted from the hot disk. The neutrino luminosities are so large that an appreciable fraction (some few percent!) of neutrinos annihilate with antineutrinos creating the clean fireball necessary to power gamma-ray bursts.

  20. Gamma Ray Burst Discoveries with SWIFT

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2007-01-01

    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. There has been tremendous recent progress in our understanding of bursts with the new data from the SWIFT mission. SWIFT was launched in November 2004 and is an international multiwavelength observatory designed to determine the origin of bursts and use them to probe the early Universe. Findings from the mission will be presented with emphasis on the relativistic outflows from GRBs. A huge step forward has been made in our understanding of the mysterious short GRBs. High redshift bursts have been detected from enormous explosions early in the universe. GRBs have been found with giant X-ray flares occurring in their afterglow, challenging predictions of the fireball model. These, and other topics, will be discussed.

  1. 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.

  2. Observing Gamma-ray Bursts with GLAST

    NASA Technical Reports Server (NTRS)

    McEnery, Julie

    2008-01-01

    The Gamma-ray Large Area Telescope (GLAST) is a satellite-based observatory to study the high-energy gamma-ray sky. The Large Area Telescope, the main instrument, is a pair-conversion telescope which will survey the sky in the energy range 20 MeV to greater than 300 GeV. The LAT's wide field of view (greater than 2 sr), large effective area and low deadtime combine to provide excellent high-energy gamma-ray observations of GRB. To tie these frontier high-energy observations to the better-known properties at lower energies, a second instrument, the GLAST Burst Monitor (GBM) will provide important spectra and timing in the 8 keV to 30 MeV range. Upon detection of a GRB by the LAT or the GBM, the spacecraft can autonomously repoint to keep the GRB location within the LAT field of view, allowing high-energy afterglow observations. We describe how the instruments, spacecraft, and ground system work together to provide observations of gamma-ray bursts from 8 keV to over 300 GeV and provide rapid notification of these observations to the wider gamma-ray burst community. Analysis and simulation tools dedicated to the GRB science have been developed. In this contribution we show the expected LAT sensitivity obtained with such simulations, and illustrate the results we expect from GLAST observations with spectral and temporal analysis of simulated GRB.

  3. Swift: A Gamma Ray Bursts Explorer

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2003-01-01

    Swift is a NASA gamma-ray burst MIDEX mission that is in development for launch in December 2003. It is a multiwavelength transient observatory for GRB astronomy. The goals of the mission are to determine the origin of GRBs and their afterglows and use bursts to probe the early Universe. It will also.perform a survey of the hard X-ray sky to a sensitivity level of -1 mCrab. A wide-field camera will detect more than a hundred GRBs per year to 5 times fainter than BATSE. Sensitive narrow-field X-ray and UV/optical telescopes will be pointed at the burst location in 20 to 70 sec by an autonomously controlled 'swift' spacecraft. For each burst, arcsec positions will be determined and optical/UV/X-ray/gamma-ray spectrophotometry performed. Measurements of redshift will be made for many of the bursts. The instrumentation is a combination of superb existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (approximately 0.5 square meter) CdZnTe detector array. The hardware is currently in final stages of fabrication and initial stages of integration and test. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift.

  4. Research in cosmic and gamma ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stone, Edward C.; Mewaldt, Richard A.; Prince, Thomas A.

    1992-01-01

    Discussed here is research in cosmic ray and gamma ray astrophysics at the Space Radiation Laboratory (SRL) of the California Institute of Technology. The primary activities discussed involve the development of new instrumentation and techniques for future space flight. In many cases these instrumentation developments were tested in balloon flight instruments designed to conduct new investigations in cosmic ray and gamma ray astrophysics. The results of these investigations are briefly summarized. Specific topics include a quantitative investigation of the solar modulation of cosmic ray protons and helium nuclei, a study of cosmic ray positron and electron spectra in interplanetary and interstellar space, the solar modulation of cosmic rays, an investigation of techniques for the measurement and interpretation of cosmic ray isotopic abundances, and a balloon measurement of the isotopic composition of galactic cosmic ray boron, carbon, and nitrogen.

  5. Positron annihilation in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.

    1990-01-01

    Emission features appear at energies of 350 to 450 keV in the spectra of a number of gamma ray burst sources. These features were interpreted as electron-positron annihilation lines, redshifted by the gravitational field near the surface of a neutron star. Evidence that gamma ray bursts originate at neutron stars with magnetic field strengths of approx. 10(exp 12) Gauss came from recent observations of cyclotron scattering harmonics in the spectra of two bursts. Positrons could be produced in gamma ray burst sources either by photon-photon pair production or by one-photon pair production in a strong magnetic field. The annihilation of positrons is affected by the presence of a strong neutron star magnetic field in several ways. The relaxation of transverse momentum conservation causes an intrinsic broadening of the two-photon annihilation line and there is a decrease in the annihilation cross section below the free-space value. An additional channel for one-photon annihilation also becomes possible in high magnetic fields. The physics of pair production and annihilation near strongly magnetized neutron stars will be reviewed. Results from a self-consistent model for non-thermal synchrotron radiation and pair annihilation are beginning to identify the conditions required to produce observable annihilation features from strongly magnetized plasmas.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

    1999-01-01

    Guided by the Supervised pattern recognition algorithm C4.5, we examine the three gamma-ray burst classes identified by Mukherjee et al. C4.5 provides strong statistical support for this classification. However, with C4.5 and our knowledge of the 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 I (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 I or Class 2 (low fluence, short, hard). Using classified bursts from the BATSE 4B Catalog, we plot log(N>P) vs. log(P) curves and study spectral features of each class. We find that the two classes are relatively distinct on the basis of 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 I and Class 2 bursts. In the process of studying burst class characteristics, we identify a new bias that affects measurement of burst fluences and durations. Using a simple model of how burst duration can be underestimated, we generally characterize how this fluence duration bias affects BATSE measurements, and demonstrate the type of effect it can have on the BATSE fluence vs. peak flux diagram.

  11. Gamma-ray burst theory after Swift.

    PubMed

    Piran, Tsvi; Fan, Yi-Zhong

    2007-05-15

    Afterglow observations in the pre-Swift era confirmed to a large extend the relativistic blast wave model for gamma-ray bursts (GRBs). Together with the observations of properties of host galaxies and the association with (type Ic) SNe, this has led to the generally accepted collapsar origin of long GRBs. However, most of the afterglow data was collected hours after the burst. The X-ray telescope and the UV/optical telescope onboard Swift are able to slew to the direction of a burst in real time and record the early broadband afterglow light curves. These observations, and in particular the X-ray observations, resulted in many surprises. While we have anticipated a smooth transition from the prompt emission to the afterglow, many observed that early light curves are drastically different. We review here how these observations are changing our understanding of GRBs. PMID:17293324

  12. Gamma rays, cosmic rays, and galactic structure

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1977-01-01

    Observations of cosmic and gamma radiation by SAS-2 satellite are summarized and analyzed to determine processes responsible for producing observed galactic radiation. In addition to the production of gamma rays in discrete galactic objects such as pulsars, there are three main mechanisms by which high-energy (greater than 100 MeV) radiation is produced by high-energy interactions involving cosmic rays in interstellar space. These processes, which produce what may be called diffuse galactic gamma-rays, are: (1) the decay of pi mesons produced by interactions of cosmic ray nucleons with interstellar gas nuclei; (2) the bremsstrahlung radiation produced by cosmic ray electrons interacting in the Coulomb fields of nuclei of interstellar gas atoms; and (3) Compton interactions between cosmic ray electrons and low-energy photons in interstellar space.

  13. 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.

  14. The Swift Gamma Ray Burst Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2004-01-01

    Swift is an international mission managed by NASA as part of its MIDEX program. It is a multiwavelength transient observatory for GRB astronomy that will launch in 2004. The goals of the mission are to determine the origin of GRBs and their afterglows and use bursts to probe the early Universe. A wide field gamma-ray camera will detect more than a hundred GRBs per year to 2-5 times fainter than BATSE. Sensitive narrow-field X-ray, and UV/optical telescopes will be pointed at the burst location in 20 to 75 sec by an autonomously controlled 'swift' spacecraft. For each burst, arcsec positions will be determined and optical/UV/x-ray/gamma-ray spectrophotometry performed. Measurements of redshift will be made for many of the bursts. The instrumentation is a combination of superb existing flight-spare hardware and design from XMM and Spectrum-X/JET-X contributed by collaborators in the UK and Italy and development of a coded-aperture camera with a large-area (approx. 0.5 square meter) CdZnTe detector array. The instruments have now completed their fabrication phase and are integrated on the observatory for final testing. Key components of the mission are vigorous follow-up and outreach programs to engage the astronomical community and public in Swift. The talk will describe the mission and its status and give a summary of our plans for GRB operations.

  15. 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.

  16. 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.

  17. Radio Flares from Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  18. Research in cosmic and gamma ray astrophysics

    NASA Technical Reports Server (NTRS)

    Stone, E. C.; Davis, L., Jr.; Mewaldt, R. A.; Prince, T. A.

    1989-01-01

    Research activities in cosmic rays, gamma rays, and astrophysical plasmas are covered. The activities are divided into sections and described, followed by a bibliography. The astrophysical aspects of cosmic rays, gamma rays, and of the radiation and electromagnetic field environment of the Earth and other planets are investigated. These investigations are performed by means of energetic particle and photon detector systems flown on spacecraft and balloons.

  19. Gravitational waves and short gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Predoi, Valeriu

    2012-07-01

    Short hard gamma-ray bursts (GRB) are believed to be produced by compact binary coalescences (CBC) { either double neutron stars or neutron star{black hole binaries. The same source is expected to emit strong gravitational radiation, detectable with existing and planned gravitational wave observatories. The focus of this work is to describe a series of searches for gravitational waves (GW) from compact binary coalescence (CBC) events triggered by short gamma-ray burst detections. Specifically, we will present the motivation, frameworks, implementations and results of searches for GW associated with short gamma-ray bursts detected by Swift, Fermi{GBM and the InterPlanetary Network (IPN) gamma-ray detectors. We will begin by presenting the main concepts that lay the foundation of gravitational waves emission, as they are formulated in the theory of General Relativity; we will also brie y describe the operational principles of GW detectors, together with explaining the main challenges that the GW detection process is faced with. Further, we will motivate the use of observations in the electromagnetic (EM) band as triggers for GW searches, with an emphasis on possible EM signals from CBC events. We will briefly present the data analysis techniques including concepts as matched{filtering through a collection of theoretical GW waveforms, signal{to{ noise ratio, coincident and coherent analysis approaches, signal{based veto tests and detection candidates' ranking. We will use two different GW{GRB search examples to illustrate the use of the existing coincident and coherent analysis methods. We will also present a series of techniques meant to improve the sensitivity of existing GW triggered searches. These include shifting background data in time in order to obtain extended coincident data and setting a prior on the GRB inclination angle, in accordance with astrophysical observations, in order to restrict the searched parameter space. We will describe the GW data analysis

  20. 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

  1. Fast radio burst/gamma-ray burst cosmography

    SciTech Connect

    Gao, He; Zhang, Bing; Li, Zhuo E-mail: zhang@physics.unlv.edu

    2014-06-20

    Recently, both theoretical arguments and observational evidence suggested that a small fraction of fast radio bursts (FRBs) could be associated with gamma-ray bursts (GRBs). If such FRB/GRB association systems are commonly detected in the future, the combination of dispersion measures (DM) derived from FRBs and redshifts derived from GRBs makes these systems a plausible tool to conduct cosmography. We quantify uncertainties in deriving the redshift-dependent DM{sub IGM} as a function of z and test how well dark energy models can be constrained with Monte Carlo simulations. We show that with several tens of FRB/GRB systems potentially detected in a decade or so, one may reach reasonable constraints on wCDM models. When combined with Type Ia supernova (SN Ia) data, unprecedented constraints on the dark energy equation of state may be achieved, thanks to the prospects of detecting FRB/GRB systems at relatively high redshifts. The ratio between the mean value and luminosity distance (D {sub L}(z)) is insensitive to dark energy models. This gives the prospect of applying SN Ia data to calibrate using a relatively small sample of FRB/GRB systems, allowing a reliable constraint on the baryon inhomogeneity distribution as a function of redshift. The methodology developed in this paper can also be applied if the FRB redshifts can be measured by other means. Some caveats of putting this method into practice are also discussed.

  2. High-redshift Gamma-Ray Burst Studies with GLAST

    SciTech Connect

    Bissaldi, Elisabetta; Longo, Francesco; Barbiellini, Guido; Calura, Francesco; Matteucci, Francesca

    2007-05-01

    We compare predicted Type Ib/c supernova (SN) rates with the observed long-duration gamma-ray burst (GRB) rates both locally and as a function of redshift. To do that, we assume different star formation histories in galaxies of different morphological type: ellipticals, spirals and irregulars. In particular, the predicted Type Ib/c SN rate (SNRIb/c) is always higher than the GRB rate, as expected, suggesting that only a small fraction (0.1-1%) of them become GRBs. We predict a ratio between the cosmic GRB rate and the cosmic SNRIb/c in the range 10-2 - 10-3, in agreement with previous estimates. Finally, due to the high star formation in spheroids at high redshift, we predict more GRBs at high redshift than previous estimates, a prediction which awaits to be proven by future observations by GLAST. Based on our studies and on the current LAT performance, an estimate of the detection possibility of this high-redshift burst population is finally presented.

  3. 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.

  4. 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.

  5. 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

  6. Gravitational wave bursts from cosmic superstrings with Y-junctions

    SciTech Connect

    Binetruy, P.; Bohe, A.; Hertog, T.; Steer, D. A.

    2009-12-15

    Cosmic superstring loops generically contain strings of different tensions that meet at Y-junctions. These loops evolve nonperiodically in time, and have cusps and kinks that interact with the junctions. We study the effect of junctions on the gravitational wave signal emanating from cosmic string cusps and kinks. We find that earlier results on the strength of individual bursts from cusps and kinks on strings without junctions remain largely unchanged, but junctions give rise to additional contributions to the gravitational wave signal coming from strings expanding at the speed of light at a junction and kinks passing through a junction.

  7. 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.

  8. Radiative Transfer In Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Beloborodov, Andrei

    We propose to develop state-of-the-art numerical tools for radiative transfer calculations in gamma-ray bursts (GRBs). We will investigate two problems: (1) Production and heating of photons at the early (opaque) stage of the explosion, which controls the brightness and spectral shape of the jet photospheric emission. (2) Transfer of GRB radiation through the external blast wave. Our recent results suggest that this transfer generates the GeV flash observed in GRBs, providing key information on the explosion and its progenitor. We will test our models against observations.

  9. 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.

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

    PubMed

    Hümmer, Svenja; Baerwald, Philipp; Winter, Walter

    2012-06-01

    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. PMID:23003939

  11. 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.

  12. 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.

  13. Gamma-Ray Burst Prompt Emission

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    2015-01-01

    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.

  14. Gamma-Ray Burst Prompt Emission

    NASA Astrophysics Data System (ADS)

    Zhang, Bing

    2014-12-01

    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.

  15. Measuring Cosmological Parameters with Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Amati, Lorenzo; Della Valle, Massimo

    2013-12-01

    In a few dozen seconds, gamma ray bursts (GRBs) emit up to 1054 erg in terms of an equivalent isotropically radiated energy Eiso, so they can be observed up to z 10. Thus, these phenomena appear to be very promising tools to describe the expansion rate history of the universe. Here, we review the use of the Ep,i-Eiso correlation of GRBs to measure the cosmological density parameter ΩM. We show that the present data set of GRBs, coupled with the assumption that we live in a flat universe, can provide independent evidence, from other probes, that ΩM 0.3. We show that current (e.g. Swift, Fermi/GBM, Konus-WIND) and forthcoming gamma ray burst (GRB) experiments (e.g. CALET/GBM, SVOM, Lomonosov/UFFO, LOFT/WFM) will allow us to constrain ΩM with an accuracy comparable to that currently exhibited by Type Ia supernovae (SNe-Ia) and to study the properties of dark energy and their evolution with time.

  16. The interplanetary gamma ray burst network

    NASA Astrophysics Data System (ADS)

    Cline, T.

    The Interplanetary Gamma-Ray Burst Network (IPN) is providing gamma-ray burst (GRB) alerts and localizations at the maximum rate anticipated before the launch of the Swift mission. The arc-minute source precision of the IPN is again permitting searches for GRB afterglows in the radio and optical regimes with delays of only hours up to 2 days. The successful addition of the Mars Odyssey mission has compensated for the loss of the asteroid mission NEAR, to reconstitute a fully long- baseline interplanetary network, with Ulysses at > 5 AU and Konus-Wind and HETE-2 near the Earth. In addition to making unassisted GRB localizations that enable a renewed supply of counterpart observations, the Mars/Ulysses/Wind IPN is confirming and reinforcing GRB source localizations with HETE-2. It has also confirmed and reinforced localizations with the BeppoSAX mission before the BeppoSAX termination in May and has detected and localized both SGRs and an unusual hard x-ray transient that is neither an SGR nor a GRB. This IPN is expected to operate until at least 2004.

  17. MAXI observations of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Serino, Motoko; Sakamoto, Takanori; Kawai, Nobuyuki; Yoshida, Atsumasa; Ohno, Masanori; Ogawa, Yuji; Nishimura, Yasunori; Fukushima, Kosuke; Higa, Masaya; Ishikawa, Kazuto; Ishikawa, Masaki; Kawamuro, Taiki; Kimura, Masashi; Matsuoka, Masaru; Mihara, Tatehiro; Morii, Mikio; Nakagawa, Yujin E.; Nakahira, Satoshi; Nakajima, Motoki; Nakano, Yuki; Negoro, Hitoshi; Onodera, Takuya; Sasaki, Masayuki; Shidatsu, Megumi; Sugimoto, Juri; Sugizaki, Mutsumi; Suwa, Fumitoshi; Suzuki, Kazuhiko; Tachibana, Yutaro; Takagi, Toshihiro; Toizumi, Takahiro; Tomida, Hiroshi; Tsuboi, Yohko; Tsunemi, Hiroshi; Ueda, Yoshihiro; Ueno, Shiro; Usui, Ryuichi; Yamada, Hisaki; Yamamoto, Takayuki; Yamaoka, Kazutaka; Yamauchi, Makoto; Yoshidome, Koshiro; Yoshii, Taketoshi

    2014-10-01

    The Monitor of All-sky X-ray Image (MAXI) Gas Slit Camera (GSC) detects gamma-ray bursts (GRBs), including bursts with soft spectra, such as X-ray flashes (XRFs). MAXI/GSC is sensitive to the energy range from 2 to 30 keV. This energy range is lower than other currently operating instruments which are capable of detecting GRBs. Since the beginning of the MAXI operation on 2009 August 15, GSC observed 35 GRBs up to the middle of 2013. One third of them were also observed by other satellites. The rest of them show a trend to have soft spectra and low fluxes. Because of the contribution of those XRFs, the MAXI GRB rate is about three times higher than those expected from the BATSE log N-log P distribution. When we compare it to the observational results of the Wide-field X-ray Monitor on the High Energy Transient Explorer 2, which covers the the same energy range as that of MAXI/GSC, we find the possibility that many of the MAXI bursts are XRFs with Epeak lower than 20 keV. We discuss the source of soft GRBs observed only by MAXI. The MAXI log N-log S distribution suggests that the MAXI XRFs are distributed over a closer distance than hard GRBs. Since the distributions of the hardness of galactic stellar flares and X-ray bursts overlap with those of MAXI GRBs, we discuss the possibility of confusion of such galactic transients with the MAXI GRB samples.

  18. Search for ultrashort gamma-ray bursts from evaporating primordial black holes

    NASA Astrophysics Data System (ADS)

    Vereshkov, G. M.; Petkov, V. B.

    2015-02-01

    Cosmic gamma-ray bursts from evaporating primordial black holes for the evaporation model with relativistic phase transitions have been sought in the data from the Andyrchy extensive air shower (EAS) array. This model predicts ultrashort (≃10-13 s) gamma-ray bursts with the spectrum with the maximum intensities simultaneously at the photon energies of 100 MeV and 100 GeV. Such ultrashort gamma-ray bursts can be detected by EAS arrays located on mountains as EASs with a uniform lateral distribution. A limit on the concentration of evaporating primordial black holes in a local region of the Galaxy for this evaporation model has been obtained from information accumulated during a live time of 4.23 yr.

  19. 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.

  20. 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

  1. Is there cosmological time dilation in gamma-ray bursts?

    NASA Technical Reports Server (NTRS)

    Band, David L.

    1994-01-01

    Norris et al. report that the temporal structure of faint gamma-ray bursts is longer than that of bright bursts, as expected for time dilation in the cosmological models of burst origin. I show that the observed trends can easily be produced by a burst luminosity function and thus may not result from cosmological effects. A cosmological signature may be present, but the tests Norris et al. present are not powerful enough to detect these signatures.

  2. 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. PMID:23630379

  3. 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.

  4. Gamma-ray Burst Energetics an the Gamma-ray Burst Hubble Diagram: Promises and Limitations

    NASA Technical Reports Server (NTRS)

    Bloom, J. S.; Frail, D. A.; Kulkarni, S. R.

    2003-01-01

    We present a complete sample of 29 gamma-ray bursts (GRBs) for which it has been possible to determine temporal breaks (or limits) from their afterglow light curves. We interpret these breaks within the framework of the uniform conical jet model, incorporating realistic estimates of the ambient density and propagating error estimates on the measured quantities. In agreement with our previous analysis of a smaller sample, the derived jet opening angles of those 16 bursts with redshifts result in a narrow clustering of geometrically corrected gamma-ray energies about 1.33 x 10(exp 51) ergs; the burst-to-burst variance about this value is 0.35 dex, a factor of 2.2. Despite this rather small scatter, we demonstrate in a series of GRB Hubble diagrams that the current sample cannot place meaningful constraints upon the fundamental parameters of the universe. Indeed, for GRBs to ever be useful in cosmographic measurements, we argue the necessity of two directions. First, GRB Hubble diagrams should be based upon fundamental physical quantities such as energy, rather than empirically derived and physically ill-understood distance indicators (such as those based upon prompt burst time-profiles and spectra). Second, a more homogeneous set should be constructed by culling subclasses from the larger sample. These subclasses, although now first recognizable by deviant energies, ultimately must be identifiable by properties other than those directly related to energy. We identify a new subclass of GRBs (" f-GRBs ") that appear both underluminous by factors of at least 10 and exhibit a rapid fading (f(sub nu is proportional to t(sup -2) at early times (t < or = 0.5 day). About 10%-20% of observed long-duration bursts appear to be f-GRBs.

  5. 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).

  6. On the bimodal distribution of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Mao, Shude; Narayan, Ramesh; Piran, Tsvi

    1994-01-01

    Kouveliotou et al. recently confirmed that gamma-ray bursts are bimodal in duration. In this paper we compute the statistical properties of the short (less than or = 2 s) and long (greater than 2 s) bursts using a method of analysis that makes no assumption regarding the location of the bursts, whether in the Galaxy or at a cosmological distance. We find the 64 ms channel on Burst and Transient Source Experiment (BATSE) to be more sensitive to short bursts and the 1024 ms channel to be more sensitive to long bursts. We show that all the currently available data are consistent with the simple hypothesis that both short and long bursts have the same spatial distribution and that within each population the sources are standard candles. The rate of short bursts per unit volume is about 40% of the rate of long bursts. Although the durations of short and long gamma-ray bursts span several orders of magnitude and the total energy of a typical short burst is smaller than that of a typical long burst by a factor of about 20, surprisingly the peak luminosities of the two kinds of bursts are equal to within a factor of about 2.

  7. Gravitational wave: gamma-ray burst connections.

    PubMed

    Hough, Jim

    2007-05-15

    After 35 years of experimental research, we are rapidly approaching the point at which gravitational waves (GWs) from astrophysical sources may be directly detected by the long-baseline detectors LIGO (USA), GEO 600 (Germany/UK), VIRGO (Italy/France) and TAMA 300 (Japan), which are now in or coming into operation.A promising source of GWs is the coalescence of compact binary systems, events which are now believed to be the origin of short gamma-ray bursts (GRBs). In this paper, a brief review of the state of the art in detector development and exploitation will be given, with particular relevance to a search for signals associated with GRBs, and plans for the future will be discussed. PMID:17293333

  8. POPULATION III GAMMA-RAY BURSTS

    SciTech Connect

    Meszaros, P.; Rees, M. J.

    2010-06-01

    We discuss a model of Poynting-dominated gamma-ray bursts from the collapse of very massive first generation (Pop. III) stars. From redshifts of order 20, the resulting relativistic jets would radiate in the hard X-ray range around 50 keV and above, followed after roughly a day by an external shock component peaking around a few keV. On the same timescales an inverse Compton component around 75 GeV may be expected, as well as a possible infrared flash. The fluences of these components would be above the threshold for detectors such as Swift and Fermi, providing potentially valuable information on the formation and properties of what may be the first luminous objects and their black holes in the high redshift universe.

  9. Soft-spectrum gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Laros, J. G.; Fenimore, E. E.; Fikani, M. M.; Klebesadel, R. W.; Kane, S. R.

    1985-01-01

    A typical gamma to ray burst (GRB), when observed over the approximately 30 keV to 1 MeV range, has a 1 to 10 s duration and a spectrum describable in terms of a several-hundred-keV exponential function. However, KONUS data indicate that some GRBs may belong to a separate class of short (approximately 0.1 s), soft (kT 50 keV) events. This result has been questioned because the KONUS experiments, with only 4 s spectral time resolution and a lack of information approximately 30 keV, are not particularly well suited for the detection and study of these bursts. The UC Berkely/Los Alamos Solar X-Ray Spectrometer/GRB experiment on the International Cometry Explorer (ICE), with nearly continuous coverage of approxiomately one-sixth of the sky down to 5 keV at 0.5 s resolution, is better designed for such a task. Using ICE data, it was confirmed that soft-spectrum events do indeed exist, apparently with properties that set them apart from the general GRB population. Results from the ICE experiment are presented.

  10. Gamma-ray bursts and collisionless shocks

    NASA Astrophysics Data System (ADS)

    Waxman, E.

    2006-12-01

    Particle acceleration in collisionless shocks is believed to be responsible for the production of cosmic-rays over a wide range of energies, from a few GeV to > 1020 eV, as well as for the non-thermal emission of radiation from a wide variety of high energy astrophysical sources. A theory of collisionless shocks based on first principles does not, however, exist. Observations of γ-ray burst (GRB) 'afterglows' provide a unique opportunity for diagnosing the physics of relativistic collisionless shocks. Most GRBs are believed to be associated with explosions of massive stars. Their 'afterglows', delayed low energy emission following the prompt burst of γ-rays, are well accounted for by a model in which afterglow radiation is due to synchrotron emission of electrons accelerated in relativistic collisionless shock waves driven by the explosion into the surrounding plasma. Within the framework of this model, some striking characteristics of collisionless relativistic shocks are implied. These include the generation of downstream magnetic fields with energy density exceeding that of the upstream field by ~8 orders of magnitude, the survival of this strong field at distances ~1010 skin-depths downstream of the shock and the acceleration of particles to a power-law energy spectrum, d log n/d logɛ ap -2, possibly extending to 1020 eV. I review in this talk the phenomenological considerations, based on which these characteristics are inferred, and the challenges posed to our current models of particle acceleration and magnetic field generation in collisionless shocks. Some recent theoretical results derived based on the assumption of a self-similar shock structure are briefly discussed. Invited review presented at the 33rd annual European Physical Society Conference, Rome, 2006.

  11. First Results from the Swift Gamma Ray Burst Mission

    NASA Technical Reports Server (NTRS)

    Gehreis, Neil

    2005-01-01

    Swift is now in orbit after a beautiful launch on November 20, 2004. It is a multiwavelength observatory designed specifically to study the fascinating gamma-ray bursts. The goals are to determine the origin of bursts and use them to probe the early Universe. 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 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. First results from the mission will be presented, including observations of bright GRBs, faint GRBs, short GRBs and a super-giant flare from the soft gamma repeater SGRl806-20.

  12. Neutrinos from Gamma Ray Bursts in the IceCube and ARA Era

    NASA Astrophysics Data System (ADS)

    Guetta, Dafne

    2016-07-01

    In this review I discuss the ultra-high energy neutrinos (UHEN) originated from Cosmic-Rays propogation (GZK neutrinos) and from Gamma Ray Bursts (GRBs), and discuss their detectability in kilometers scale detectors like ARA and IceCube. While GZK neutrinos are expected from cosmic ray interactions on the CMB, the GRB neutrinos depend on the physics inside the sources. GRBs are predicted to emit UHEN in the prompt and in the later "after-glow" phase. I discuss the constraints on the hadronic component of GRBs derived from the search of four years of IceCube data for a prompt neutrino fux from gamma-ray bursts (GRBs) and more in general I present the results of the search for high-energy neutrinos interacting within the IceCube detector between 2010 and 2013.

  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. 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.

  15. Search for Prompt Neutrino Emission from Gamma-Ray Bursts with IceCube

    NASA Astrophysics Data System (ADS)

    Aartsen, M. G.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Becker Tjus, J.; Becker, K.-H.; BenZvi, S.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Brayeur, L.; Bretz, H.-P.; Brown, A. M.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Christy, B.; Clark, K.; Classen, L.; Clevermann, F.; Coenders, S.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; Dunkman, M.; Eagan, R.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Eisch, J.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Frantzen, K.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Gier, D.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Goodman, J. A.; Góra, D.; Grant, D.; Gretskov, P.; Groh, J. C.; Groß, A.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallen, P.; Hallgren, A.; Halzen, F.; Hanson, K.; Hebecker, D.; Heereman, D.; Heinen, D.; Helbing, K.; Hellauer, R.; Hellwig, D.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Homeier, A.; Hoshina, K.; Huang, F.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Japaridze, G. S.; Jero, K.; Jlelati, O.; Jurkovic, M.; Kaminsky, B.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kheirandish, A.; Kiryluk, J.; Kläs, J.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Koob, A.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kriesten, A.; Krings, K.; Kroll, G.; Kroll, M.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larsen, D. T.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Lünemann, J.; Madsen, J.; Maggi, G.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meli, A.; Meures, T.; Miarecki, S.; Middell, E.; Middlemas, E.; Milke, N.; Miller, J.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke, A.; Odrowski, S.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Paul, L.; Penke, Ö.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Pütz, J.; Quinnan, M.; Rädel, L.; Rameez, M.; Rawlins, K.; Redl, P.; Rees, I.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Riedel, B.; Robertson, S.; Rodrigues, J. P.; Rongen, M.; Rott, C.; Ruhe, T.; Ruzybayev, B.; Ryckbosch, D.; Saba, S. M.; Sander, H.-G.; Sandroos, J.; Santander, M.; Sarkar, S.; Schatto, K.; Scheriau, F.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schukraft, A.; Schulte, L.; Schulz, O.; Seckel, D.; Sestayo, Y.; Seunarine, S.; Shanidze, R.; Smith, M. W. E.; Soldin, D.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stanisha, N. A.; Stasik, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Taavola, H.; Taboada, I.; Tamburro, A.; Tepe, A.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Tosi, D.; Tselengidou, M.; Unger, E.; Usner, M.; Vallecorsa, S.; van Eijndhoven, N.; Vandenbroucke, J.; van Santen, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallraff, M.; Weaver, Ch.; Wellons, M.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Whitehorn, N.; Wichary, C.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Ziemann, J.; Zoll, M.

    2015-05-01

    We present constraints derived from a search of four years of IceCube data for a prompt neutrino flux from gamma-ray bursts (GRBs). A single low-significance neutrino, compatible with the atmospheric neutrino background, was found in coincidence with one of the 506 observed bursts. Although GRBs have been proposed as candidate sources for ultra-high-energy cosmic rays, our limits on the neutrino flux disfavor much of the parameter space for the latest models. We also find that no more than ˜1% of the recently observed astrophysical neutrino flux consists of prompt emission from GRBs that are potentially observable by existing satellites.

  16. On the nature of gamma-ray burst time dilations

    NASA Technical Reports Server (NTRS)

    Wijers, Ralph A. M. J.; Paczynski, Bohdan

    1994-01-01

    The recent discovery that faint gamma-ray bursts are stretched in time relative to bright ones has been interpreted as support for cosmological distances: faint bursts have their durations redshifted relative to bright ones. It was pointed out, however, that the relative time stretching can also be produced by an intrinsic correlation bewteen duration and luminosity of gamma-ray bursts in a nearby, bounded distribution. While both models can explain the average amount of time stretching, we find a difference between them in the way the duration distribution of faint bursts deviates from that of bright ones, assuming the luminosity function of gamma-ray bursts is independent of distance. This allows us to distinguish between these two broad classes of model on the basis of the duration distributions of gamma-ray bursts, leading perhaps to an unambiguous determination of the distance scale of gamma-ray bursts. We apply our proposed test to the second Burst and Transient Source Experiment (BATSE) catalog and conclude, with some caution, that the data favor a cosmological interpretation of the time dilation.

  17. New insights from cosmic gamma rays

    NASA Astrophysics Data System (ADS)

    Roland, Diehl

    2016-04-01

    The measurement of gamma rays from cosmic sources at ~MeV energies is one of the key tools for nuclear astrophysics, in its study of nuclear reactions and their impacts on objects and phenomena throughout the universe. Gamma rays trace nuclear processes most directly, as they originate from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. Additionally, the unique gamma-ray signature from the annihilation of positrons falls into this astronomical window and is discussed here: Cosmic positrons are often produced from β-decays, thus also of nuclear physics origins. The nuclear reactions leading to radioactive isotopes occur inside stars and stellar explosions, which therefore constitute the main objects of such studies. In recent years, both thermonuclear and core-collapse supernova radioactivities have been measured though 56Ni, 56Co, and 44Ti lines, and a beginning has thus been made to complement conventional supernova observations with such measurements of the prime energy sources of supernova light created in their deep interiors. The diffuse radioactive afterglow of massive-star nucleosynthesis in gamma rays is now being exploited towards astrophysical studies on how massive stars feed back their energy and ejecta into interstellar gas, as part of the cosmic cycle of matter through generations of stars enriching the interstellar gas and stars with metals. Large interstellar cavities and superbubbles have been recognised to be the dominating structures where new massive-star ejecta are injected, from 26Al gamma-ray spectroscopy. Also, constraints on the complex interiors of stars derive from the ratio of 60Fe/26Al gamma rays. Finally, the puzzling bulge-dominated intensity distribution of positron annihilation gamma rays is measured in greater detail, but still not understood; a recent microquasar flare provided evidence that such objects may be prime sources for positrons in interstellar space, rather than

  18. 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.

  19. Research in cosmic and gamma ray astrophysics: Cosmic physics portion

    NASA Technical Reports Server (NTRS)

    Stone, Edward C.; Mewaldt, Richard A.; Schindler, Stephen

    1993-01-01

    Research in particle astrophysics at the Space Radiation Laboratory (SRL) of the California Institute of Technology is supported under NASA Grant NAGW-1919. A three-year proposal for continuation of support was submitted a year ago and put into effect 1 October 1992. This report is the combined progress report and continuation application called for under the Federal Demonstration Project. Gamma-ray Astrophysics at SRL is separately supported under NAGW-1919 and will be separately summarized and proposed. This report will document progress and plans for our particle spectroscopy activities and for related data analysis, calibration, and community service activities. A bibliography and a budget will be attached as appendices. The Caltech SRL research program includes a heavy emphasis on elemental and isotopic spectroscopy of energetic particles in the cosmic radiation; in solar, interplanetary, and anomalous 'cosmic' radiation; and in planetary magnetospheres as discussed.

  20. Gamma-Ray Bursts 2012 Conference

    NASA Astrophysics Data System (ADS)

    It is a pleasure to announce the next combined Fermi/Swift GRB conference covering recent advances in all aspects of gamma-ray burst observations and theory. This conference will be held in Munich, Germany, on 7-11 May 2012, and follows similar previous combined Fermi/Swift meetings in Huntsville (Oct. 2008) and Annapolis (Nov. 2010). Gamma-ray bursts are the most energetic explosions in the Universe and are thought to be the birth signatures of black holes. This is an exciting time in the GRB field as various missions provide a wealth of new data on this still puzzling phenomenon. The Fermi misson provides unprecedented spectral coverage over 7 decades in energy, and among others discovered new spectral components which challenge our standard picture of the prompt emission. The Swift mission continuous to swiftly monitor and locate GRBs in multiple wavebands, providing the basis for all ground-based follow-up observations towards redshift measurements and afterglow and host property investigations. AGILE, INTEGRAL, Suzaku and Konus continue to provide crucial information on GRB properties, and the MAXI mission provides an all sky X-ray monitoring of transients. There is also growing capability for follow-up observations by ground-based telescopes at basically all wavelengths. Besides the classical optical/infrared/radio observations, searches are underway for TeV emission, neutrinos and gravitational waves. Moreover, new experiments are expected to have returned first data, among others POGO on the prompt polarization properties, UFFO on very early optical emission, or ALMA on sub-millimeter properties. And last but not least, the unexpected is bringing us child-like astonishments at least once per year with a "GRB-trigger" which turns out to be not related to GRBs. Complementing all these new observational results, a huge theoretical effort is underway to understand the GRB phenomenon and keep up with the constant new puzzles coming from the data. This conference

  1. 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.

  2. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2007-01-01

    This viewgraph presentation reviews the current understanding of Gamma Ray Bursts. It covers the Long GRBs, our current understanding of Collapsar, Short GRBs, afterglows, and reduced trigger threshold. It also discusses the Hard X-ray Sky Survey.

  3. Gamma Ray Burst Observations with Swift and GLAST

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2007-01-01

    The Swift and GLAST missions promise a great increase in our understanding of the gamma-ray universe. Swift was launched in November 2004 with a primary objective to study gamma-ray bursts. All instruments are performing well and more than 200 GRBs have been studied in detail. Major advances have already been made in the areas of short bursts, high redshift events and afterglow physics. The GLAST mission is scheduled for launch in fall 2007. It features a large newtechnology instrument for high energy gamma-ray observations. Hundreds of gamma-ray bursts will be detected by the LAT and GBM instruments. The talk will discuss the GRB science available with GLAST and the opportunities for joint Swift and GLAST observations of bursts.

  4. AI gamma-ray burst classification: Methodology/preliminary results

    NASA Astrophysics Data System (ADS)

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

    1998-05-01

    Artificial intelligence (AI) classifiers can be used to classify unknowns, refine existing classification parameters, and identify/screen-out ineffectual parameters. We present an AI methodology for classifying gamma-ray bursts, along with some preliminary results.

  5. Statistical and Time Analyses of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Marani, Gabriela Fabiana

    1998-10-01

    If Gamma-Ray Bursts (GRBs) are cosmological in origin, different signatures are expected to be found in the available \\batse catalog and time series. Cross-correlation with extragalactic objects and gravitational lensing by intervening objects are some examples of these particular features. A new statistical method to perform 2-D angular cross-correlations between GRB positions and different catalogs of extragalactic objects has been implemented. For the best located 74 3B GRBs, a 2.5-σ level association with rich, nearby Abell clusters is found. If all the cluster are taken into account, a 3.5-σ association is found for the best located 27 3B bursts. Another 2.5-σ excess is found between soft GRBs and the whole Abell catalog. On the other hand, excesses of the order of ~ 3.5-4-σ are found between the best located 10 to 380 bursts and the nearest, intrinsically brightest radio quiet quasars. However, the correlations appears to be due to statistical fluctuations and the excesses are only suggestive of a physical association. A fully automated search among 1,235 4B bursts has been carried out to look for statistical similarities in the GRB time series. No two GRBs are found to be identical to within the statistical limits of the data, regardless of their position on the sky. GRBs that appear statistically similar in one energy channel are either dissimilar in other energy channels or too dim for a significant statistical comparison. One consequence of the search for statistical similarities is that no gravitational lensing of GRBs by foreground galaxies have been found. Given this null result, and assuming no GRB rate density or luminosity evolution, and that QSO images are distorted by the same galaxy field, a conservative upper limit to the redshift is derived, zmax ~ 4.22 at a 2-σ confidence level, for an Einstein-de Sitter universe and bursts with P > 1 photon cm-2 s-1. The gravitational lensing rates have been computed for different Friedmann

  6. Closest Gamma Ray Burst Providing Scientists With Crucial Test for Burst Physics

    NASA Astrophysics Data System (ADS)

    2003-05-01

    The closest Gamma Ray Burst (GRB) yet known is providing astronomers with a rare opportunity to gain information vital to understanding these powerful cosmic explosions. Extremely precise radio-telescope observations already have ruled out one proposed mechanism for the bursts. "This is the closest and brightest GRB we've ever seen, and we can use it to decipher the physics of how these bursts work," said Greg Taylor of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. Taylor worked with Dale Frail, also of the NRAO, along with Prof. Shri Kulkarni and graduate student Edo Berger of Caltech in studying a GRB detected on March 29, 2003. The scientists presented their findings to the American Astronomical Society's meeting in Nashville, TN. VLBA image of GRB 030329 VLBA IMAGE of GRB 030329 CREDIT: NRAO/AUI/NSF (Click on Image for Larger Version) Taylor and Frail used the National Science Foundation's (NSF) Very Long Baseline Array (VLBA) and other radio telescopes to study the burst, known as GRB 030329. In a series of observations from April 1 to May 19, they determined the size of the expanding "fireball" from the burst and measured its position in the sky with great precision. At a distance of about 2.6 billion light-years, GRB 030329 is hardly next door. However, compared to other GRBs at typical distances of 8-10 billion light-years, it presents an easier target for study. "We only expect to see one burst per decade this close," said Frail. The precise measurement of the object's position allowed the scientists to show that one theoretical model for GRBs can be ruled out. This model, proposed in 2000, says that the radio-wave energy emitted by the GRB comes from "cannonballs" of material shot from the explosion at extremely high speeds. "The 'cannonball model' predicted that we should see the radio-emitting object move across the sky by a specific amount. We have not seen that motion," Taylor said. The currently standard "fireball model" of GRBs

  7. Cosmic gamma-rays and cosmic nuclei above 1 TeV

    NASA Technical Reports Server (NTRS)

    Watson, A. A.

    1986-01-01

    Work on cosmic gamma rays and cosmic nuclei above I TeV is described and evaluated. The prospect that gamma ray astronomy above I TeV will give new insights into high energy cosmic ray origin within our galaxy is particularly bright.

  8. "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.

  9. Gamma-ray burst variability above 4 MeV

    NASA Technical Reports Server (NTRS)

    Schwartz, R. A.; Ling, J. C.; Wheaton, W. A.; Jacobson, A. S.; Mahoney, W. A.

    1985-01-01

    The relationship between the hard X-ray and gamma ray emissions during four bursts using the anti-coincidence shields of the High Energy Astronomy Observatory 3 (HEAO 3) Gamma Ray Spectrometer is explored. Recent observations of gamma ray bursts by the Solar Maximum Mission Gamma Ray Spectrometer (GRS) have shown that high energy emission above 1 MeV is a common and energetically important feature (Matz et al. 1985). Time histories of four gamma ray bursts in 3 energy bands ( keV, around 511 keV, and 4 MeV) with 10.24 a resolution show that the 4 MeV flux is only weakly coupled to the spectrum below approximately 600 keV.

  10. The study of gamma-ray bursts on Prognoz spacecraft

    NASA Astrophysics Data System (ADS)

    Estulin, I. V.

    A joint French-Soviet experiment to identify the sources of gamma-ray bursts in space is described. The main instrument used in the experiment was a SNEG-2MP gamma-ray detector array consisting of two scintillation proportional counters and a collimator with an aperture angle of 18 degrees. The position of the SNEG-2MP array on the Prognoz-6 spacecraft is illustrated. A total of 15 gama-ray bursts was observed in the energy range 30-50 keV. The positions of the burst sources were localized on a standard star map, and the results are presented in photographic form.

  11. 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. PMID:17293337

  12. Structure in gamma ray burst time profiles: Statistical Analysis 1

    NASA Technical Reports Server (NTRS)

    Lestrade, John Patrick

    1992-01-01

    Since its launch on April 5, 1991, the Burst And Transient Source Experiment (BATSE) has observed and recorded over 500 gamma-ray bursts (GRB). The analysis of the time profiles of these bursts has proven to be difficult. Attempts to find periodicities through Fourier analysis have been fruitless except one celebrated case. Our goal is to be able to qualify the observed time-profiles structure. Before applying this formation to bursts, we have tested it on profiles composed of random Poissonian noise. This paper is a report of those preliminary results.

  13. 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.

  14. DMSP satellites as gamma-ray burst detectors

    SciTech Connect

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

    1993-12-31

    Gamma-ray burst detectors are aboard three US 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 available from GRO or other data.

  15. Cosmological aspects of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Behkam, Razieh

    Gamma-ray burst observations provide a great opportunity for cosmography in high redshift. Some tight correlations between different physical properties of GRBs are discovered and used for cosmography. However, data selection, assumptions, systematic uncertainty and some other issues affect most of them. Most importantly, until the physical origin of a relation is understood, one should be cautious to employ the relation to utilize Gamma ray bursts for cosmography. In the first part of this dissertation, I use Liang-Zhang correlation to constrain Λ Cold Dark Matter standard cosmology and a particular class of brane cosmology (brane-induced gravity model). With the most probable model being Om = 0.23 and O Λ = 0.77 for flat ΛCDM cosmology and O m = 0.18 and Wrc = 0.17 for flat brane-induced gravity cosmology, my result for the energy components of these two models is comparable with the result from SNIa observation. With average uncertainty of distance modulus being 0.2771, the two discussed cosmologies are indistinguishable using my current sample of GRB with redshift ranging between 0.1685 and 3.2. I argue that by expanding my sample and adding more low and high redshift GRBs and also with improvement in using GRB for cosmography, we might be able to distinguish between different cosmological models and tighten the most probable model. Looking into correlation and evolution of GRB prompt emission and afterglow has many advantages. It helps to open windows to comprehend the physics of GRBs and examine different GRB models. It is also possible to use GRB correlation as an accurate redshift estimator and more importantly to constrain the cosmological parameters. XRT flares of GRB afterglow are thought to be the result of central engine activity. Studying this component leads us to understand GRB flare and central engine nature. In the next part of this dissertation, I study the correlation and evolution of different prompt emission and afterglow GRB properties and

  16. 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.

  17. Localization of Gamma-Ray Bursts Using the Fermi Gamma-Ray Burst Monitor

    NASA Astrophysics Data System (ADS)

    Connaughton, V.; Briggs, M. S.; Goldstein, A.; Meegan, C. A.; Paciesas, W. S.; Preece, R. D.; Wilson-Hodge, C. A.; Gibby, M. H.; Greiner, J.; Gruber, D.; Jenke, P.; Kippen, R. M.; Pelassa, V.; Xiong, S.; Yu, H.-F.; Bhat, P. N.; Burgess, J. M.; Byrne, D.; Fitzpatrick, G.; Foley, S.; Giles, M. M.; Guiriec, S.; van der Horst, A. J.; von Kienlin, A.; McBreen, S.; McGlynn, S.; Tierney, D.; Zhang, B.-B.

    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.

  18. Gamma-ray bursts from colliding strange stars

    NASA Technical Reports Server (NTRS)

    Haensel, P.; Paczynski, B.; Amsterdamski, P.

    1991-01-01

    The rate of collisions between the neutron stars is about 0.0001/yr in the galaxy and about 0.00001/yr within the Hubble distance. The collisions are the final phases of binary orbit decay driven by gravitational radiation and may produce gamma-ray bursts detectable at extragalactic distances. If strange stars exist then their collisions must release about 10 to the 50th ergs in gamma rays over 0.2 s. Such events should be detectable out to 1 Gpc with the current instruments. The distance to the majority of gamma-ray bursts is not known at this time. The Burst and Transient Source Experiment (BATSE) on Gamma Ray Observatory should determine the distance scale by determining the angular distribution of very weak bursts. If the majority of gamma-ray bursts turn out to be extragalactic, and if their distances are about 1 Gpc, then the collisions between strange stars may be the least speculative events that might account for so energetic bursts.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Gamma-ray bursts from neutron star detonation

    SciTech Connect

    Michel, F.C.

    1988-09-25

    A phenomenological gamma-ray burst model postulating the injection of 10/sup 51/--10/sup 53/ ergs into a neutron star by Paczyn-acute-accentski and by Goodman is closely reminiscent of what a relativistic version of a type I supernova might look like. Burning to tightly bound quark complexes (i.e., particles) could go explosively, just as the final burning of helium to iron disrupts a white darf in some models of type I supernovae. Particle theorists have for some years entertained the possibility that compressing nuclear matter may lead irreversibly to an exothermic formation of ''quark'' matter. From stellar evolution, we know that nuclear burning does not proceed directly to the known endpoint (iron) but is halted at various intermediate stages (e.g., at helium). Thus when the central densities of a neutron star begin to rise to that at which a transition to quark matter would be expected (10--20 times nuclear) owing to accretion or fusion with a companion neutron star, explosive burning may take place. Active galactic nuclei could be powered by such events and are therefore possible source regions. The particles themselves would be massive tightly bound bosons having zero spin, zero charge, and zero magnetic moment, hence could possible evidence themselves in the form of ''dark'' ( = nonluminous) matter or ''WIMPs'' (weakly interacting massive particles). The relativistic shocks from such events should accelerate cosmic rays more efficiently than the usual supernova shocks.

  5. Internal Luminosity Distribution of Bright Gamma-Ray Bursts and its Relation to Duration and Spectral Hardness

    NASA Technical Reports Server (NTRS)

    Horack, John M.; Hakkila, Jon

    1997-01-01

    We present first results from a comprehensive investigation into the distribution of luminosity within the 50 brightest cosmic gamma-ray bursts detected by the Burst and Transient Source Experiment (BATSE). The internal luminosity function psi(L) is defined such that the quantity psi(L)dL represents the fraction of total emission time during which the burst possesses a luminosity between L and L + dL. For these brightest bursts, the psi(L) functions are quasi-power-law-like and decrease in amplitude with increasing luminosity. Through investigation of both individual psi(L) distributions and data from the ensemble of bursts, we demonstrate a high probability for correlation between the shape of the internal luminosity function as measured by the average logarithmic slope and the burst duration as measured by the T(sub 90) parameter and, with lower significance, between the shape of psi(L) and the burst photon-fluence spectral index. We furthermore demonstrate a correlation between burst hardness ratio and duration in these brightest bursts which is opposite to that of the entire gamma-ray burst ensemble.

  6. Perspectives of the GAMMA-400 space observatory for high-energy gamma rays and cosmic rays measurements

    NASA Astrophysics Data System (ADS)

    Topchiev, N. P.; Galper, A. M.; Bonvicini, V.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Bakaldin, A. V.; Bergstrom, L.; Berti, E.; Bigongiari, G.; Bobkov, S. G.; Boezio, M.; Bogomolov, E. A.; Bonechi, S.; Bongi, M.; Bottai, S.; Castellini, G.; Cattaneo, P. W.; Cumani, P.; Dalkarov, O. D.; Dedenko, G. L.; De Donato, C.; Dogiel, V. A.; Finetti, N.; Gorbunov, M. S.; Gusakov, Yu V.; Hnatyk, B. I.; Kadilin, V. V.; Kaplin, V. A.; Kaplun, A. A.; Kheymits, M. D.; Korepanov, V. E.; Larsson, J.; Leonov, A. A.; Loginov, V. A.; Longo, F.; Maestro, P.; Marrocchesi, P. S.; Men'shenin, A. L.; Mikhailov, V. V.; Mocchiutti, E.; Moiseev, A. A.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu; Papini, P.; Pearce, M.; Picozza, P.; Rappoldi, A.; Ricciarini, S.; Runtso, M. F.; Ryde, F.; Serdin, O. V.; Sparvoli, R.; Spillantini, P.; Stozhkov, Yu I.; Suchkov, S. I.; Taraskin, A. A.; Tavani, M.; Tiberio, A.; Tyurin, E. M.; Ulanov, M. V.; Vacchi, A.; Vannuccini, E.; Vasilyev, G. I.; Yurkin, Yu T.; Zampa, N.; Zirakashvili, V. N.; Zverev, V. G.

    2016-02-01

    The GAMMA-400 gamma-ray telescope is intended to measure the fluxes of gamma-rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. Such measurements concern the following scientific tasks: investigation of point sources of gamma-rays, studies of the energy spectra of Galactic and extragalactic diffuse emission, studies of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons. Also the GAMMA- 400 instrument provides the possibility for protons and nuclei measurements up to knee. But the main goal for the GAMMA-400 mission is to perform a sensitive search for signatures of dark matter particles in high-energy gamma-ray emission. To fulfill these measurements the GAMMA-400 gamma-ray telescope possesses unique physical characteristics in comparison with previous and present experiments. The major advantage of the GAMMA-400 instrument is excellent angular and energy resolution for gamma-rays above 10 GeV. The GAMMA-400 experiment will be installed onboard of the Navigator space platform, manufactured by the NPO Lavochkin Association. The expected orbit will be a highly elliptical orbit (with apogee 300.000 km and perigee 500 km) with 7 days orbital period. An important profit of such an orbit is the fact that the full sky coverage will always be available for gamma ray astronomy.

  7. A Search for High-Energy Neutrino Emission from Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Whitehorn, Nathan

    2012-05-01

    A century after their discovery, the origin of cosmic rays remains one of the most enduring mysteries in physics. They can have energies that exceed 1020 eV, a hundred million times as energetic as the most powerful Earth-bound particle accelerators and must therefore be produced in the universe's most violent environments. Direct observation of their origins, however, has proven difficult due to deflection of charged cosmic ray particles in galactic and intergalactic magnetic fields, obscuring their true origins. Astronomy using electrically neutral particles, such as photons and neutrinos, does not, however, share this difficulty. This work presents a search for neutrino emission from one of the primary candidates for the sources of the highest-energy cosmic rays, Gamma-Ray Bursts, using the recently-completed IceCube neutrino telescope located at the South Pole. The null result obtained from this search contradicts well-established predictions for the neutrino flux from Gamma-Ray Bursts if they are the cosmic ray sources, forcing a reevaluation of these theoretical models.

  8. 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.

  9. 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.

  10. The gamma-ray burst monitor for the Russian Mars 1996 mission

    SciTech Connect

    Ziock, K.P.; Bixler, J.; Cline, T.

    1997-08-01

    The authors describe an innovative detector designed primarily for the study of cosmic gamma-ray bursts aboard interplanetary spacecraft. The experiment is a fully functional, low cost, low mass, low-power instrument, which, when combined with other similar instruments, has the capability of localizing bursts to arcminute precision. The burst monitor is based on a photomultiplier tube and a plastic/CsI(Tl) phoswich detector and records photons in the 20--150-keV energy range with time resolutions up to several milliseconds. In addition, it records photon energy spectra. Events in the plastic scintillator are distinguished by a pulse shape discrimination circuit and are used to count electrons and protons. In a planetary orbiter or fly-by mission, this capability can be used to detect the presence of a magnetosphere. The authors describe in detail a version of this instrument which was built for the Russian Mars 1996 mission.

  11. 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.

  12. Luminosity Distributions of Cosmological Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Hakkila, Jon; Meegan, Charles A.; Horack, John M.; Pendleton, Geoffrey N.; Briggs, Michael S.; Mallozzi, Robert S.; Koshut, Thomas M.; Preece, Robert D.; Paciesas, William S.

    1996-05-01

    The intrinsic luminosities of gamma-ray bursts are found to be constrained by the BATSE/PVO combined intensity distribution, assuming that (1) bursts originate in {LAMBDA} = 0, {OMEGA} = 1 Friedmann cosmology with a nonevolving density distribution, (2) the nonevolving intrinsic luminosity function can be modeled as a truncated power law, and (3) burst spectra are modeled as power laws with identical spectral indices. These simplifying assumptions allow constraints to be placed on luminosity functions in cosmological gamma-ray burst scenarios and indicate that standard-candle sources are not favored. In general, either the minimum burst luminosity L_min_ or the maximum burst luminosity L_max_ are known, with the opposite end of the luminosity function unconstrained. Both L_max_ and L_min_ must be specified for luminosity power-law indices near 2. When these results are combined with other studies measuring other cosmological burst signatures, it is possible that the intrinsic luminosity function contains more low-luminosity bursts than high-luminosity ones.

  13. 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; Schoenfelder, Volker

    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.

  14. 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.

  15. The average GeV-band emission from gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Lange, J.; Pohl, M.

    2013-03-01

    Aims: We analyze the emission in the 0.3-30 GeV energy range of gamma-ray bursts detected with the Fermi Gamma-ray Space Telescope. We concentrate on bursts that were previously only detected with the Gamma-Ray Burst Monitor in the keV energy range. These bursts will then be compared to the bursts that were individually detected with the Large Area Telescope at higher energies. Methods: To estimate the emission of faint GRBs we used nonstandard analysis methods and sum over many GRBs to find an average signal that is significantly above background level. We used a subsample of 99 GRBs listed in the Burst Catalog from the first two years of observation. Results: Although most are not individually detectable, the bursts not detected by the Large Area Telescope on average emit a significant flux in the energy range from 0.3 GeV to 30 GeV, but their cumulative energy fluence is only 8% of that of all GRBs. Likewise, the GeV-to-MeV flux ratio is less and the GeV-band spectra are softer. We confirm that the GeV-band emission lasts much longer than the emission found in the keV energy range. The average allsky energy flux from GRBs in the GeV band is 6.4 × 10-4 erg cm-2 yr-1 or only ~4% of the energy flux of cosmic rays above the ankle at 1018.6 eV.

  16. Closest Gamma Ray Burst Providing Scientists With Crucial Test for Burst Physics

    NASA Astrophysics Data System (ADS)

    2003-05-01

    The closest Gamma Ray Burst (GRB) yet known is providing astronomers with a rare opportunity to gain information vital to understanding these powerful cosmic explosions. Extremely precise radio-telescope observations already have ruled out one proposed mechanism for the bursts. "This is the closest and brightest GRB we've ever seen, and we can use it to decipher the physics of how these bursts work," said Greg Taylor of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. Taylor worked with Dale Frail, also of the NRAO, along with Prof. Shri Kulkarni and graduate student Edo Berger of Caltech in studying a GRB detected on March 29, 2003. The scientists presented their findings to the American Astronomical Society's meeting in Nashville, TN. VLBA image of GRB 030329 VLBA IMAGE of GRB 030329 CREDIT: NRAO/AUI/NSF (Click on Image for Larger Version) Taylor and Frail used the National Science Foundation's (NSF) Very Long Baseline Array (VLBA) and other radio telescopes to study the burst, known as GRB 030329. In a series of observations from April 1 to May 19, they determined the size of the expanding "fireball" from the burst and measured its position in the sky with great precision. At a distance of about 2.6 billion light-years, GRB 030329 is hardly next door. However, compared to other GRBs at typical distances of 8-10 billion light-years, it presents an easier target for study. "We only expect to see one burst per decade this close," said Frail. The precise measurement of the object's position allowed the scientists to show that one theoretical model for GRBs can be ruled out. This model, proposed in 2000, says that the radio-wave energy emitted by the GRB comes from "cannonballs" of material shot from the explosion at extremely high speeds. "The 'cannonball model' predicted that we should see the radio-emitting object move across the sky by a specific amount. We have not seen that motion," Taylor said. The currently standard "fireball model" of GRBs

  17. 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.

  18. Orbital Observatory GLAST - New Step in the Study of Cosmic Gamma Radiation: Mission Overview

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander

    2008-01-01

    This viewgraph presentation is a overview of the Gamma-ray Large Area Space Telescope (GLAST), now named Fermi Space Telescope. The new telescope is scheduled for launch in the middle of 2008. It contains the high energy gamma-ray telescope LAT (Large Area Telescope) and the GMB (GLAST Burst Monitor). The science objectives of GLAST cover almost every area of high energy astrophysics, including Active Galactic Nuclei (AGN), including Extragalactic background light (EBL), Gamma-ray bursts (GRB), Pulsars, Diffuse gamma-radiation, EGRET unidentified sources, Solar physics, Origin of Cosmic Rays and, Dark Matter and New Physics. Also included in this overview is a discussion of the preparation to the analysis of the science data.

  19. Properties of multiple event gamma ray bursts. [GB 820301

    SciTech Connect

    Lochner, J.C. )

    1991-09-01

    We present results from a study of 37 multiple event gamma ray bursts found in the monitoring data of the PVO gamma ray burst detector. We define these bursts as those which have two or more distinct emission events separated by a return to the background intensity. Significant correlation exists between the duration of the first event and the duration of the second event, while some correlation exists between the hardness of the events and only weak correlation exists in the intensity of the events. Although the time profiles of events in a burst may be similar, as measured in the phase portrait, there is no general rule about the degree of similarity of the time profiles. Subdividing the data according to the recurrence time, we find a tendency for the strength of the correlation in the hardness to increase with decreasing separation between the events.

  20. Spectral evolution of pulse structures in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Norris, J. P.; Share, G. H.; Messina, D. C.; Dennis, B. R.; Desai, U. D.; Cline, T. L.

    1986-01-01

    The Hard X-Ray Burst Spectrometer (HXRBS) and Gamma-Ray Spectrometer (GRS) data from the Solar Maximum Mission satellite have been searched for gamma-ray bursts with sufficient intensities and relatively simple time profiles such that their spectral behavior may be studied on a time scale of about 1 s. Ten such events were observed with the GRS experiment, and four of these were also detected within the HXRBS field of view. Details are presented for two moderately intense bursts with relatively simple structure. The spectral evolutions of the remaining events are summarized briefly. Results suggest a pattern in the spectral evolution within burst pulses: a tendency for the high-energy emission to lead the low-energy emission, in contrast to the correlation of intensity and spectral hardness reported by Golenetskii et al. (1983).

  1. 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.

  2. 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.

  3. Gamma-ray burst of November 19, 1978

    SciTech Connect

    Zenchenko, V.M.; Kuznetsov, A.V.; Mersov, G.A.; Estulin, I.V.; Vedrenne, G.; Niel, M.; Hurley, K.

    1980-03-01

    The ..gamma..-ray burst recorded on November 19, 1978, by the Venera 11 and Venera 12 space probes and the Prognoz 7 satellite is described. The source of this burst is confined to an ellipse measuring 0'.84 x 15'.4, centered at ..cap alpha..=19/sup 0/.064, delta=-28/sup 0/.858 (1950.0). No identification can yet be made between the source and any stellar object.

  4. Cosmology and the subclasses of the gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Mészáros, Attila; Horváth, István; Řípa, Jakub; Bagoly, Zsolt; Balázs, Lajos G.; Veres, Péter

    2011-02-01

    Several statistical studies - done also by the authors of this contribution - show that there are three subclasses of gamma-ray bursts. They can be called as short, intermediate and long ones, because they can be separated with respect to their durations. The short and intermediate bursts are distributed anisotropically on the sky. This behavior is highly remarkable, and can have a cardinal impact on the cosmology. The subject of this contribution is a survey of this topic.

  5. 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.

  6. Gamma Ray Burst Discoveries by the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    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 and calibrated in Germany, 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. Early results 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. Observations of magnetars, galactic transients, supernovae, AGN and many other types of sources are also being performed

  7. Gamma Ray Burst Discoveries by the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    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 since November 20, 2004 and all hardware is performing well. A new-technology wide-field gamma-ray camera is detecting 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 50-100 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. There has been a break-through in the longstanding mystery of short GRBs; they appear to be caused by merging neutron stars. 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.

  8. Gamma Ray Burst Discoveries by the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    The NASA Swift mission is an innovative new multiwavelength observatory designed to determine the origin of gamma-ray bursts and use them to probe the early Universe. Swift is now in orbit since November 20, 2004 and all hardware is performing well. A new-technology wide-field gamma-ray camera is detecting 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 50-100 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 and a half of findings from the mission will be presented. There has been a break-through in the long-standing mystery of short GRBs; they appear to be caused by merging neutron stars. High redshift bursts have been detected leading to a better understanding of star formation rates and distant galaxy environments. A fascinating nearby burst triggered Swift and enabled the best early-time observations of an emerging coincident Type lb/c supernova. GRBs have been found with giant X-ray flares occurring in their afterglow.

  9. Gamma Ray Burst Discoveries by the Swift Mission

    NASA Astrophysics Data System (ADS)

    Gehrels, Neil; Swift Team

    2006-09-01

    The NASA Swift mission is an innovative new multiwavelength observatory designed to determine the origin of gamma-ray bursts and use them to probe the early Universe. Swift is now in orbit since November 20, 2004 and all hardware is performing well. A new-technology wide-field gamma-ray camera is detecting 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 50-100 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 and a half of findings from the mission will be presented. There has been a break-through in the long-standing mystery of short GRBs; they appear to be caused by merging neutron stars. High redshift bursts have been detected leading to a better understanding of star formation rates and distant galaxy environments. A fascinating nearby burst triggered Swift and enabled the best early-time observations of an emerging coincident Type Ib/c supernova. GRBs have been found with giant X-ray flares occurring in their afterglow.

  10. Gamma Ray Burst Discoveries by the Swift Mission

    NASA Astrophysics Data System (ADS)

    Gehrels, Neil

    2006-04-01

    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 since November 20, 2004 and all hardware is performing well. A new-technology wide-field gamma-ray camera is detecting 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 50-100 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. There has been a break-through in the long-standing mystery of short GRBs; they appear to be caused by merging neutron stars. 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.

  11. Gamma Ray Burst Discoveries by the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    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.

  12. 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.

  13. THE HIGH ENERGY BUDGET ALLOCATIONS IN SHOCKS AND GAMMA RAY BURSTS

    SciTech Connect

    Eichler, David; Guetta, Dafne; Pohl, Martin

    2010-10-10

    The statistical distribution of energies among particles responsible for long gamma-ray burst (GRB) emission is analyzed in light of recent results of the Fermi Observatory. The all-sky flux, F{sub {gamma}}, recorded by the Gamma-Ray Burst Monitor (GBM) is shown, despite its larger energy range, to be not significantly larger than that reported by the Burst and Transient Explorer, suggesting a relatively small flux in the 3-30 MeV energy range. The present-day energy input rate in {gamma}-rays recorded by the GBM from long GRBs is found, assuming star formation rates in the literature, to be W-dot(0)=0.5 F{sub {gamma}H}/c=5x10{sup 42}erg Mpc{sup -3} yr{sup -1}. The Large Area Telescope fluence, when observed, is about 5%-10% per decade of the total, in good agreement with the predictions of saturated, nonlinear shock acceleration. The high-energy component of long GRBs, as measured by Fermi, is found to contain only {approx}10{sup -2.5} of the energy needed to produce ultrahigh-energy cosmic rays (UHECRs) above 4 EeV, assuming the latter to be extragalactic, when various numerical factors are carefully included, if the cosmic-ray source spectrum has a spectral index of -2. The observed {gamma}-ray fraction of the required UHECR energy is even smaller if the source spectrum is softer than E {sup -2}. The AMANDA II limits rule out such a GRB origin for UHECRs if much more than 10{sup -2} of the cosmic-ray energy goes into neutrinos that are within, and simultaneous with, the {gamma}-ray beam. It is suggested that 'orphan' neutrinos out of the {gamma}-ray beam might be identifiable via orphan afterglow or other wide angle signatures of GRBs in lieu of coincidence with prompt {gamma}-rays, and it is recommended that feasible single neutrino trigger criteria be established to search for such coincidences.

  14. 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.

  15. Early optical polarization of a gamma-ray burst afterglow.

    PubMed

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

    2007-03-30

    We report the optical polarization of a gamma-ray burst (GRB) afterglow, obtained 203 seconds after the initial burst of gamma-rays from GRB 060418, using a ring polarimeter on the robotic Liverpool Telescope. Our robust (2sigma) upper limit on the percentage of polarization, less than 8%, coincides with the fireball deceleration time at the onset of the afterglow. The combination of the rate of decay of the optical brightness and the low polarization at this critical time constrains standard models of GRB ejecta, ruling out the presence of a large-scale ordered magnetic field in the emitting region. PMID:17363631

  16. 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.

  17. 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).

  18. 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.

  19. Limits on neutrino emission from gamma-ray bursts with the 40 string IceCube detector.

    PubMed

    Abbasi, R; Abdou, Y; Abu-Zayyad, T; Adams, J; Aguilar, J A; Ahlers, M; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Bay, R; Bazo Alba, J L; Beattie, K; Beatty, J J; Bechet, S; Becker, J K; Becker, K-H; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Braun, J; Brown, A M; Buitink, S; Carson, M; Chirkin, D; Christy, B; Clem, J; Clevermann, F; Cohen, S; Colnard, C; Cowen, D F; D'Agostino, M V; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Demirörs, L; Depaepe, O; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Díaz-Vélez, J C; Dierckxsens, M; Dreyer, J; Dumm, J P; Ehrlich, R; Eisch, J; Ellsworth, R W; Engdegård, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Foerster, M M; Fox, B D; Franckowiak, A; Franke, R; Gaisser, T K; Gallagher, J; Geisler, M; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Grant, D; Griesel, T; Gross, A; Grullon, S; Gurtner, M; Ha, C; Hallgren, A; Halzen, F; Han, K; Hanson, K; Heinen, D; Helbing, K; Herquet, P; Hickford, S; Hill, G C; Hoffman, K D; Homeier, A; Hoshina, K; Hubert, D; Huelsnitz, W; Hülss, J-P; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobsen, J; Japaridze, G S; Johansson, H; Joseph, J M; Kampert, K-H; Kappes, A; Karg, T; Karle, A; Kelley, J L; Kemming, N; Kenny, P; Kiryluk, J; Kislat, F; Klein, S R; Köhne, J-H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, S; Koskinen, D J; Kowalski, M; Kowarik, T; Krasberg, M; Krings, T; Kroll, G; Kuehn, K; Kuwabara, T; Labare, M; Lafebre, S; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lehmann, R; Lünemann, J; Madsen, J; Majumdar, P; Marotta, A; Maruyama, R; Mase, K; Matis, H S; Meagher, K; Merck, M; Mészáros, P; Meures, T; Middell, E; Milke, N; Miller, J; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Nam, J W; Naumann, U; Niessen, P; Nygren, D R; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Ono, M; Panknin, S; Paul, L; Pérez de los Heros, C; Petrovic, J; Piegsa, A; Pieloth, D; Porrata, R; Posselt, J; Price, P B; Prikockis, M; Przybylski, G T; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Rizzo, A; Rodrigues, J P; Roth, P; Rothmaier, F; Rott, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Sander, H-G; Santander, M; Sarkar, S; Schatto, K; Schmidt, T; Schoenwald, A; Schukraft, A; Schultes, A; Schulz, O; Schunck, M; Seckel, D; Semburg, B; Seo, S H; Sestayo, Y; Seunarine, S; Silvestri, A; Slipak, A; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stephens, G; Stezelberger, T; Stokstad, R G; Stoyanov, S; Strahler, E A; Straszheim, T; Sullivan, G W; Swillens, Q; Taavola, H; Taboada, I; Tamburro, A; Tarasova, O; Tepe, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Tosi, D; Turčan, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Voigt, B; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Weaver, C; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wischnewski, R; Wissing, H; Wolf, M; Woschnagg, K; Xu, C; Xu, X W; Yodh, G; Yoshida, S; Zarzhitsky, P

    2011-04-01

    IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18)  eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence. PMID:21561178

  20. Repeating sources of classical gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Wang, V. C.; Lingenfelter, R. E.

    1995-01-01

    From an analysis of the first catalog of the Burst and Transient Source Experiment (BATSE) experiment (Fishman et al. 1993, 1994a) on the Compton Gamma Ray Observatory (CGRO), we find an excessive number of pairs of gamma-ray bursts which are clustered in both a space and time . The angular separation between the two bursts in each pair is less than their positional uncertainties, and the interval between their occurrence times is within several days. Optimizing the signal, we find that the probability of observing such a clustered excess froma Poisson ensemble is approximately 2 x 10(exp -5). We suggest that these bursts arise from repeating sources. A detailed study of the most prolific source, GBS 0855-00, is presented in a separate paper (Wang & Lingenfelter 1993a, b). Unlike most of the 'soft' gamma-ray repeaters, these repeating bursts have relatively hard spectra, complex light curves, and widely varying durations, that are indistinguishable from classical gamma-ray bursts. Although the significance of the clustered excess was optimized a posteriori, because it depends on temporal and spatial bin sized that could not be defined a priori, we can use the optimizations from the first catalog to test subsequent BATSE data sets. Unfortunately, the failure of the on-board tape recorders during the second catalog period seriously reduced the number of accurately positioned bursts (Fishman et al. 1994b), so that we can neither confirm, nor refute, the predicted repitition in that sample, and we must await the results of the third catalog.

  1. The transient gamma-ray spectrometer: A new high resolution detector for gamma-ray burst spectroscopy

    SciTech Connect

    Seifert, H.; Baker, R.; Cline, T.L.; Gehrels, N.; Jermakian, J.; Nolan, T.; Ramaty, R.; Sheppard, D.A.; Smith, G.; Stilwell, D.E.; Teegarden, B.J.; Trombka, J.; Owens, A.; Cork, C.P.; Landis, D.A.; Luke, P.N.; Madden, N.W.; Malone, D.; Pehl, R.H.; Yaver, H.; Hurley, K.; Mathias, S.; Post, A.H. Jr.

    1992-01-01

    The Transient Gamma-Ray Spectrometer (TGRS) to be flown aboard the WIND spacecraft is primarily designed to perform high resolution spectroscopy of transient gamma-ray events, such as cosmic [gamma]-ray bursts and solar flares, over the energy range 20 keV to 10 MeV with an expected spectroscopic resolution of E/[delta]E = 500. The detector itself consists of a 215 cm[sup 3] high purity n-type Ge crystal kept at cryogenic temperatures by a passive radiative cooler. The geometric field of view defined by the cooler is 170[degrees]. To avoid continuous triggers caused by soft solar events, a thin Be/Cu sun-shield around the sides of the cooler has been provided. A passive Mo/Pb occulter, which modulates signals from within [+-]5[degrees] of the ecliptic plane at the spacecraft spin frequency, is used to identify and study solar flares, as well as emission from the galactic plane and center. Thus, in addition to transient event measurements, the instrument will allow the search for possible diffuse background lines and monitor the 511 keV positron annihilation radiation from the galactic center. In order to handle the typically large burst count rates which can be in excess of 100 kHz, burst data are stored directly in an on-board 2.75 Mbit burst memory with an absolute timing accuracy of [+-]1.5 ms after ground processing. This capacity is sufficient to store the entire spectral data set of all but the largest bursts. The experiment is scheduled to be launched on a Delta II launch vehicle from Cape Canaveral in the fall of 1993.

  2. The Gamma-Ray Burst Catalog Obtained with the Gamma-Ray Burst Monitor Aboard BeppoSAX

    NASA Astrophysics Data System (ADS)

    Frontera, F.; Guidorzi, C.; Montanari, E.; Rossi, F.; Costa, E.; Feroci, M.; Calura, F.; Rapisarda, M.; Amati, L.; Carturan, D.; Cinti, M. R.; Fiume, D. Dal; Nicastro, L.; Orlandini, M.

    2009-01-01

    We report on the catalog of gamma-ray bursts (GRBs) detected with the Gamma-Ray Burst Monitor aboard the BeppoSAX satellite. It includes 1082 GRBs with 40-700 keV fluences in the range from 1.3 × 10-7 to 4.5 × 10-4 erg cm-2, and 40-700 keV peak fluxes from 3.7 × 10-8 to 7.0 × 10-5 erg cm-2 s-1. We report in the catalog some relevant parameters of each GRB and discuss the derived statistical properties.

  3. Resonant Compton scattering and gamma-ray burst continuum spectra

    NASA Technical Reports Server (NTRS)

    Baring, M. G.

    1995-01-01

    The Thomson limit of resonant inverse Compton scattering in the strong magnetic fields of neutron stars is considered as a mechanism for producing gamma-ray burst continuum spectra. Photon production spectra and electron cooling rates are presented using the full magnetic Thomson cross-section. Model emission spectra are obtained as self-consistent solutions of a set of photon and electron kinetic equations, displaying spectral breaks and other structure at gamma-ray energies.

  4. 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.

  5. 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.

  6. 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.

  7. Gamma-ray astronomy and the origin of cosmic rays

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1978-01-01

    Recent observations of cosmic gamma radiation are reviewed. It is shown that this radiation consists of an extragalactic background as well as a bright band of galactic radiation lying in the plane of the Milky Way and produced primarily by cosmic-ray collisions with interstellar gas atoms. The galactic gamma radiation is divided into a near component apparently associated with Gould's belt and a far component originating about 15,000 light years away and narrowly confined to the galactic plane. A Great Galactic Ring is identified which is 35,000 light years in diameter and in which most galactic cosmic rays are produced and supernovae and pulsars are concentrated. The physical mechanisms responsible for the production of most of the cosmic gamma rays in the Galaxy are examined, and the origin of galactic cosmic rays is considered. It is concluded that the cosmic rays are produced either in supernova explosions or in the pulsars they leave behind

  8. Revisiting the formation rate and redshift distribution of long gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Kanaan, C.; de Freitas Pacheco, J. A.

    2013-11-01

    Using a novel approach, the distribution of fluences of long gamma-ray bursts derived from the Swift-BAT catalog was reproduced by a jet-model characterized by the distribution of the total radiated energy in γ-rays and the distribution of the aperture angle of the emission cone. The best fit between simulated and observed fluence distributions permits one to estimate the parameters of the model. An evolution of the median energy of the bursts is required to adequately reproduce the observed redshift distribution of the events when the formation rate of γ-ray bursts follows the cosmic star formation rate. For our preferred model, the median jet energy evolves as EJ ∝ e0.5(1 + z) and the mean expected jet energy is 3.0 × 1049 erg, which agrees with the mean value derived from afterglow data. The estimated local formation rate is Rgrb = 290 Gpc-3 yr-1, representing less than 9% of the local formation rate of type Ibc supernovae. This result also suggests that the progenitors of long gamma-ray bursts have masses ≥ 90 M⊙ when a Miller-Scalo initial mass function is assumed.

  9. 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.

  10. 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%)

  11. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Marshall, F. E.

    2006-01-01

    Gamma Ray Bursts are the largest explosions in the Universe, and the recently launched Swift mission is a multi-wavelength observatory that has greatly expanded our ability to study them. Swift's wide-field gamma-ray camera is detecting about 100 bursts per year that are quickly viewed with sensitive X-ray and UV/optical telescopes on the observatory. Positions are rapidly released to the world to enable ground-based observations. Results from the first year of observations will be presented. The mystery of short GRBs has been solved, very high redshift bursts discovered, and enormous X-ray flares found in afterglows. These and other results will be discussed.

  12. 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.

  13. Gamma Ray Burst Discoveries with the Swift Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2006-01-01

    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. There has been tremendous recent progress in our understanding of bursts with the new data from the Swift mission. Swift was launched in November 2004 and is an international multiwavelength observatory designed to determine the origin of bursts and use them to probe the early Universe. The two years of findings fiom the mission will be presented. A huge step forward has been made in our understanding of the mysterious short GRBs. High redshift bursts have been detected from enormous explosions early in the universe. GRBs have been found with giant X-ray flares occurring in their afterglow. These, and other topics, will be discussed.

  14. Alternative temporal classification of long Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Alejandro Vasquez, Nicolas; Baquero, Andres; Andrade, David

    2015-08-01

    In order to increase the understanding on Gamma Ray Bursts, many attempts of classification have been proposed. Starting with the canonical classification into long and short GRBs, alternative classifications taking into account the cosmological origin of GRBs have been analyzed. In the present work we propose an alternative classification based on two temporal estimators, the Auto Correlation Function (ACF) of the light curves and the emission time which considered the time where the bursts engine is active. The time estimators chosen reflects the internal evolution of the GRB and the internal structure. Using a sample of 61 bright GRBs detected by SWIFT satellite with known redshift, we proposed a bimodal distribution of long bursts. The two types of bursts have different internal structure suggesting different progenitors.

  15. BALLERINA - doing Pirouettes for the Gamma-Bursts

    NASA Astrophysics Data System (ADS)

    Lund, Niels; Ballerina Consortium

    1998-12-01

    BALLERINA is a satellite project currently selected (together with 3 other candidates) for a five month phase-A study within the Danish Small-Satellite Programme. BALLERINA combines an all-sky monitor yielding instantaneous half-degree size error boxes with rapid maneuverability and a wide field X-ray telescope. The project aims to study the transition phase from the gamma-burst to the afterglow phase, and to distribute sub-arcminute positions for the bursts in near real time. We expect to be able to lock-on to the source with the X-ray telescope in less than 3 minutes from the trigger, and to provide the accurate burst position to the general astronomical community within 10 minutes. While waiting for the bursts we plan to study other transient and persistent X-ray sources .

  16. 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.

  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. 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. PMID:25167393

  19. CONSTRAINING DARK ENERGY WITH GAMMA-RAY BURSTS

    SciTech Connect

    Samushia, Lado; Ratra, Bharat E-mail: ratra@phys.ksu.ed

    2010-05-10

    We use the measurement of gamma-ray burst (GRB) distances to constrain dark energy cosmological model parameters. We employ two methods for analyzing GRB data-fitting luminosity relation of GRBs in each cosmology and using distance measures computed from binned GRB data. Current GRB data alone cannot tightly constrain cosmological parameters and allow for a wide range of dark energy models.

  20. Rossi Prize Lecture: Gamma Ray Bursts: Origins and Consequences

    NASA Astrophysics Data System (ADS)

    Meszaros, P.

    2000-12-01

    Some of the major stepping stones towards uncovering the mystery of gamma ray bursts will be discussed. This is an unfinished process, new observations being expected in the near future. I will review the current observational status, and discuss the present theoretical understanding of GRB, as well as the possible impact of future missions and experiments.

  1. Search for optical bursts from the gamma ray burst source GBS 0526-66

    NASA Technical Reports Server (NTRS)

    Seetha, S.; Sreenivasaiah, K. V.; Marar, T. M. K.; Kasturirangan, K.; Rao, U. R.; Bhattacharyya, J. C.

    1985-01-01

    Attempts were made to detect optical bursts from the gamma-ray burst source GBS 0526-66 during Dec. 31, 1984 to Jan. 2, 1985 and Feb. 23 to Feb. 24, 1985, using the one meter reflector of the Kavalur Observatory. Jan. 1, 1985 coincided with the zero phase of the predicted 164 day period of burst activity from the source (Rothschild and Lingenfelter, 1984). A new optical burst photon counting system with adjustable trigger threshold was used in parallel with a high speed photometer for the observations. The best time resolution was 1 ms and maximum count rate capability was 255,000 counts s(-1). Details of the instrumentation and observational results are presented.

  2. Fermi/Gamma-Ray Burst Monitor Observations of SGR J0501+4516 Bursts

    NASA Astrophysics Data System (ADS)

    Lin, Lin; Kouveliotou, Chryssa; Baring, Matthew G.; van der Horst, Alexander J.; Guiriec, Sylvain; Woods, Peter M.; Göǧüş, Ersin; Kaneko, Yuki; Scargle, Jeffrey; Granot, Jonathan; Preece, Robert; von Kienlin, Andreas; Chaplin, Vandiver; Watts, Anna L.; Wijers, Ralph A. M. J.; Zhang, Shuang Nan; Bhat, Narayan; Finger, Mark H.; Gehrels, Neil; Harding, Alice; Kaper, Lex; Kaspi, Victoria; Mcenery, Julie; Meegan, Charles A.; Paciesas, William S.; Pe'er, Asaf; Ramirez-Ruiz, Enrico; van der Klis, Michiel; Wachter, Stefanie; Wilson-Hodge, Colleen

    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 90 durations of the bursts can be fit with a log-normal distribution with a mean value of ~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 90 values estimated in count space (following a log-normal distribution with a mean value of ~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 peak decreases with energy flux (and fluence) to a minimum of ~30 keV at F = 8.7 × 10-6 erg cm-2 s-1, increasing steadily afterward. Two more sources exhibit a similar trend: SGRs J1550-5418 and 1806-20. The isotropic luminosity, L iso, corresponding to these flux values is roughly similar for all sources (0.4-1.5 × 1040 erg s-1).

  3. Cascaded Gamma Rays as a Probe of Cosmic Rays

    NASA Astrophysics Data System (ADS)

    Murase, Kohta

    2014-06-01

    Very-high-energy (VHE) and ultra-high-energy (UHE) gamma rays from extragalactic sources experience electromagnetic cascades during their propagation in intergalactic space. Recent gamma-ray data on TeV blazars and the diffuse gamma-ray background may have hints of the cascade emission, which are especially interesting if it comes from UHE cosmic rays. I show that cosmic-ray-induced cascades can be discriminated from gamma-ray-induced cascades with detailed gamma-ray spectra. I also discuss roles of structured magnetic fields, which suppress inverse-Compton pair halos/echoes but lead to guaranteed signals - synchrotron pair halos/echoes.

  4. Investigation of primordial black hole bursts using interplanetary network gamma-ray bursts

    DOE PAGESBeta

    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.; et al

    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

  5. Investigation of Primordial Black Hole Bursts Using Interplanetary Network Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Ukwatta, T. N.; Hurley, K.; MacGibbon, J. 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.; Frontera, F.; Guidorzi, C.; Cline, T.; Gehrels, N.; Krimm, H. A.; McTiernan, J.

    2016-07-01

    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. Assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.

  6. Observations Of Particle Acceleration In The Blast Waves Of Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Curran, Peter A.; van der Horst, A. J.; Evans, P. A.

    2010-03-01

    The electron energy distribution index, p, is a fundamental parameter of the process by which electrons are accelerated to relativistic speeds and by which they radiate, via synchrotron emission. This acceleration process is applicable to a myriad of astronomical sources, from jet sources such as AGN, X-ray binaries and gamma-ray bursts, to particle acceleration in the solar wind and supernovae, and the acceleration of cosmic rays. The accurate measurement of the distribution of p is of fundamental importance to differentiate between the possible theories of electron acceleration at any relativistic shock front. There is division as to whether the electron energy distribution index has a universal value or whether it has a distribution, and if so, what that distribution is. In this presentation we examine one such source of synchrotron emission: the blast waves of gamma-ray bursts. Using our unique Monte Carlo method, we examine the constraints placed on the distribution of p by the observed spectral indices of gamma-ray bursts and parametrize the distribution. We find that the observed distribution of spectral indices is inconsistent with a discrete value of p, but consistent with a Gaussian distribution centred at p 2.4 and having a width of 0.6. This finding rules out the theoretical work that argues for a single, universal value of p, but also demonstrates that the width of the distribution is not as wide as has been suggested by some authors.

  7. The INTEGRAL view of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Ubertini, Pietro; Corsi, A.; Foley, S.; McGlynn, S.; De Cesare, G.; Bazzano, A.

    2011-04-01

    After more than six and half years in orbit, the ESA space observatory INTEGRAL has provided new, exciting results in the soft gamma-ray energy range (from a few keV to a few MeV). With the discovery of about 700 hard X-Ray sources, it has changed our previous view of a sky composed of peculiar and “monster” sources. The new high energy sky is in fact full of a large variety of normal, very energetic emitters, characterized by new accretion and acceleration processes (see also IBIS cat4 (Bird et al., 2010). At the same time, about one GRB/month is detected and imaged by the two main gamma-ray instruments on board: IBIS and SPI. In this paper, we review the major achievements of the INTEGRAL observatory in the field of Gamma-Ray Bursts. We summarize the global properties of Gamma-Ray Bursts detected by INTEGRAL, with respect to their duration, spectral index, and peak flux distributions. We recall INTEGRAL results on the spectral lag analysis, showing how long-lag GRBs appear to form a separate population at low peak fluxes. We review the outcome of polarisation studies performed by using INTEGRAL data. Finally, concerning single GRB studies, we highlight the properties of particularly interesting Gamma-Ray Bursts in the INTEGRAL sample.

  8. 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.

  9. 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.

  10. The Fermi view of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Axelsson, Magnus; Fermi/LAT Collaboration

    2015-08-01

    The Fermi mission has brought great advances in the study of GRBs. Over 1500 gamma-ray bursts (GRBs) have been detected by the Gamma-ray Burst Monitor (GBM), and more than 100 of these are also detected by the Fermi Large Area Telescope (LAT) above 30 MeV. These high-energy detections have revealed previously unknown features in GRB spectra, including additional components and spectral cut-offs, as well as delayed and long-lived GeV emission. Interpretation of these new features has proven to be a source of vigorous debate within the GRB community. I will review recent Fermi-LAT observations of GRBs, ranging from the detection of the long-lived GRB 130427A to the broad-band fits of simultaneous X-ray and gamma-ray data, and what they reveal about the origin of the high-energy emission from GRBs.

  11. 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.

  12. Einstein observations of the 1978 November 19 gamma ray burst source field

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    It is pointed out that several years after the discovery of cosmic gamma ray bursts (GRB) their sources have not yet been identified, although searches have been conducted in optical, X-ray, and radio wavelengths. The three smallest error boxes are now related to the events of Mar. 5, 1979, Apr. 6, 1979, and Nov. 19, 1978. X-ray observations, with the Imaging Proportional Counter (IPC) of the Einstein Observatory, were made for all three locations. A description is presented of the results of the 8200 second IPC observation of the Nov. 19, 1978 GRB, made on July 1 and 2, 1980. Three sources were detected. However, two of them were outside the GRB error box. The third source is located well inside the burst error box.

  13. 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.

  14. 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.

  15. BALLERINA-Pirouettes in search of gamma burst sources

    NASA Astrophysics Data System (ADS)

    Brandt, Søren; Lund, Niels

    1999-12-01

    The cosmological origin of gamma-ray bursts (GRBs) has now been established with reasonable certainty. Many more bursts will need to be studied to establish the typical distance scale, and to map out the large variability in properties, which have been indicated by the first handful of events. We are proposing BALLERINA, a small satellite to provide accurate gamma burst positions at a rate an order of magnitude larger than from Beppo-SAX. On the experimental side, it remains a challenge to ensure the earliest detection of the X-ray afterglow. The mission proposed here allows for the first time systematic studies of the soft X-ray emission in the time interval from only a few minutes after the onset of the burst to a few hours later. In addition to positions of GRBs with accuracy better than 1'reported to the ground within a few minutes of the burst, essential for follow-up work, BALLERINA will on its own provide observations in an uncharted region of parameter space. Secondary objectives of the BALLERINA mission includes observations of the earliest phases of the outbursts of X-ray novae and other X-ray transients. BALLERINA is one of four missions currently under study for the Danish Small Satellite Program. The selection will be announced in 1999 for a planned launch in 2002-2003.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. The Hurst Exponent of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Sonbas, Eda; MacLachlan, Glen A.; Dhuga, Kalvir S.; Landay, Justin

    2016-07-01

    Using a wavelet decomposition technique, we have extracted the Hurst exponent for a sample of long and short Gamma-Ray Bursts (GRBs) detected by the Burst Alert Telescope (BAT) aboard the Swift satellite. The Hurst exponent is a scaling parameter that can be used to gauge the long-range behavior in a time series. The mean Hurst exponent for the short GRB sample is significantly smaller than that for the long GRB sample, suggesting that this index may serve as an unbiased criterion for distinguishing short and long GRBs. In addition, a K-S test for the two samples suggest that the null hypothesis can be rejected.

  1. 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.

  2. 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.

  3. Gamma-Ray Bursts and Population III Stars

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    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.

  4. 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.

  5. Are Abell Clusters Correlated with Gamma-Ray Bursts?

    NASA Technical Reports Server (NTRS)

    Hurley, K.; Hartmann, D.; Kouveliotou, C.; Fishman, G.; Laros, J.; Cline, T.; Boer, M.

    1997-01-01

    A recent study has presented marginal statistical evidence that gamma-ray burst (GRB) sources are correlated with Abell clusters, based on analyses of bursts in the BATSE 3B catalog. Using precise localization information from the Third Interplanetary Network, we have reanalyzed this possible correlation. We find that most of the Abell clusters that are in the relatively large 3B error circles are not in the much smaller IPN/BATSE error regions. We believe that this argues strongly against an Abell cluster-GRB correlation.

  6. REDSHIFT CATALOG FOR SWIFT LONG GAMMA-RAY BURSTS

    SciTech Connect

    Xiao Limin; Schaefer, Bradley E.

    2011-04-20

    We present a catalog of the redshifts for most long-duration gamma-ray bursts (GRBs) by Swift from 2004 December 20 to 2008 July 23 (258 bursts in total). All available information is collected, including spectroscopic redshifts, photometric redshift limits, and redshifts calculated from various luminosity relations. Error bars for the redshifts derived from the luminosity relations are asymmetric, with tails extended to the high-redshift end, and this effect is evaluated by looking at the 30% of Swift bursts with spectroscopic redshifts. A simulation is performed to eliminate this asymmetric effect, and the resultant redshift distribution is deconvolved. We test and confirm this simulation on the sample of bursts with known spectroscopic redshifts and then apply it to the 70% of Swift bursts that do not have spectroscopic measures. A final intrinsic redshift distribution is then made for almost all Swift bursts, and the efficiency of the spectroscopic detections is evaluated. The efficiency of spectroscopic redshifts varies from near unity at low redshift to 0.5 at z = 1, to near 0.3 at z = 4, and to 0.1 at z = 6. We also find that the fraction of GRBs with z>5 is {approx}10%, and this fraction is compared with simulations from a cosmological model.

  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. 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.

  9. 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.

  10. Understanding the Continuum Spectra of Short Soft Gamma Repeater Bursts

    NASA Technical Reports Server (NTRS)

    Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa; Finger, Mark H.; Lenter, Geoffrey; Patel, Sandeep K.; Swank, Jean

    2006-01-01

    The spectra of short soft gamma repeater (SGR) bursts at photon energies above -15 keV are often well described by an optically thin thermal bremsstrahlung model (i.e., F(E) - E^-1 * exp(-E/kT) ) with kT=20-40 keV. However, the spectral shape burst continuum at lower photon energies (down to -2 keV) is not well established. It is important to better understand the SGR burst spectral properties at lower energies since inadequate description of the burst spectral continuum could lead to incorrect conclusions, such as existence of spectral lines. Here, we present detailed spectral investigations (in 2-200 keV) of 163 bursts from SGR 1806-20, all detected with Rossi X-ray Timing Explorer during the 2004 active episode that included the giant flare on 27 December 2004. We find that the great majority of burst spectra are well represented by the combination of a blackbody plus a OTTB models.

  11. 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.

  12. 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. PMID:18583579

  13. Gamma Ray Burst Discoveries by the SWIFT Mission

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    2007-01-01

    Gamma-ray bursts are among the most fascinating occurences in the cosmos. They are thought to be the birth cries of black holes throughout the universe. The NASA SWIFT mission, in orbit since November 2004, is an innovative multiwavelenth observaroty designed to determine the origin of bursts and use them to probe the early Universe. Recent results from the mission will be presented. The long-standing mstery of short GRBs is beginning to be solved in a most interesting direction. High redshift bursts have been detected to redshift z=6.3 leading to a better understanding of star formation rates at early times. GRBs have been found with giant X-ray flares occurring in their afterglow.The very nearby GRB 060218 triggered obsevations within minutes of the full light curve of an odd suupernova Type Ic.

  14. 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.

  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. 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.

  17. 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.

  18. Theoretical Aspects of Magnetic Fields for Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Hanami, Hitoshi

    We propose magnetic cannon ball mechanism in which the collapse of a magnetosphere onto a black hole can generate strong outward Poynting flux which drives a baryon-free fireball called the magnetic cannon ball. In the early stage, the magnetic fields in the cannon ball can prepare the explanation for the cycrotoron absorptions observed by GINGA. The magnetic cannon ball can drive, in general, a relativistic outflow which interacts with the interstellar matter and forms a shock. The magnetic field in the shock approximately equal to 104 G can induce the synchrotron radiations with peaks at approximately equal to 10^2 keV observed. This magnetic field in the cannon ball can also confine the high energy protons (gamma_p > 30) which are required for delayed photons (>25 GeV) following a burst on 1994 February 17. Accretion induced collapse of a white dwarf of > 109 G, merger of a close binary and failed type Ib supernovae are possible scenarios even without the rotation of the central object. This mechanism works at the final phase of gravitational collapse even after a neutrino driven fireball proposed in most scenarios for gamma ray bursts. Twice bursts, which consist of primary neutrino driven fireball and secondary magnetic cannon ball can be induced sometime, can be explained in this model. It suggests that the magnetic cannon ball works some parts in multiple populations and delayed or multiple burst events. The final remnant in the model should be a black hole. It implies that any gamma ray bursts can have no optical counter part if they do not have a companion in a binary.

  19. 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.

  20. 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.

  1. 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)

  2. The ISEE-C gamma ray burst spectrometer

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.; Porreca, G.; Stilwell, D.; Desai, U. D.; Cline, T. L.; Hovestadt, D.

    1978-01-01

    The technical properties, operation, and expected sensitivity are discussed for an experiment intended to search for narrow lines in the spectra of gamma ray bursts during the ISEE-C mission. At the heart of the experiment is a radiatively cooled germanium solid state photon detector. The instrumentation is capable of storing the entire spectrum of all but the largest bursts in the energy range 0.05-6.5 MeV. In addition, it analyzes the signals from two CsI detectors in two other experiments on the spacecraft and records event time histories from these to a few millisecond accuracy. A background mode permits spectral analysis during quiet times and will allow the determination of physically interesting upper limits for narrow lines in the diffuse gamma ray background radiation.

  3. 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.

  4. The BATSE 5B Gamma-Ray Burst Spectral Catalog

    NASA Astrophysics Data System (ADS)

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

    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).

  5. Collapsed White Dwarfs as Gamma-Ray Burst Sources

    NASA Astrophysics Data System (ADS)

    de Paolis, F.; Ingrosso, G.; Qadir, A.

    1995-09-01

    It has been suggested by Usov (1992) that accreting white dwarfs, collapsing to neutron stars may be the sources of the gamma-ray bursts observed at cosmological distances, provided they rotate very fast and have enormously high magnetic fields. In this model the burst's durationτ is given by the ratio of pulsar kinetic energy and magneticdipole luminosity, so that in order to account for the shortest (τ ˜ 0.1 s) bursts, the pulsars must rotate very fast (with periodP ˜ 0.5 ms) and have magnetic fields of 1016 - 1017 G. Though the high pulsar frequency was anticipated (Qadir and Rafique, 1986) and has been shown to be plausible (Abramowicz, 1990), the extremely high magnetic fields seem anomalous as observed neutron stars have fields below ˜ 1013 G. The problem with Usov's proposal is reduced by incorporating the relativistic corrections for fast rotating magnetic dipoles (Belinskyet al., 1994) or magnetic stars (De Paolis and Qadir, 1994). These corrections substantially enhance the radiation efficiency due to the existence of a magnetic synchrotron effect so that the magnetic field required for the explanation of the shortest gamma-ray bursts is strongly reduced. As such the model becomes much more plausible.

  6. FERMI LIMIT ON THE NEUTRINO FLUX FROM GAMMA-RAY BURSTS

    SciTech Connect

    Li Zhuo

    2013-06-20

    If gamma-ray bursts (GRBs) produce high-energy cosmic rays, neutrinos are expected to be generated in GRBs via photo-pion productions. However, we stress that the same process also generates electromagnetic (EM) emission induced by the secondary electrons and photons, and that the EM emission is expected to be correlated with neutrino flux. Using Fermi/Large Area Telescope results on gamma-ray flux from GRBs, the GRB neutrino emission is limited to be <20 GeV m{sup -2} per GRB event on average, which is independent of the unknown GRB proton luminosity. This neutrino limit suggests that IceCube, operating at full scale, requires stacking of more than 130 GRBs in order to detect one GRB muon neutrino.

  7. Search for bursts of gamma rays of energies greater than 1 GeV

    NASA Astrophysics Data System (ADS)

    Bhat, P. N.; Gopalakrishnan, N. V.; Gupta, S. K.; Ramana Murthy, P. V.; Sreekantan, B. V.; Tonwar, S. C.; Viswanath, P. R.

    1982-06-01

    A ground-based experiment to detect cosmic gamma-ray bursts (GRB) in which the individual gamma-rays at the top of the atmosphere have energies in the GeV range has been in operation at Ootacamund, India, for nearly 1.5 years. Not a single event was observed, although five of the GRB seen by satellite-borne detectors in the MeV energy range were in the view of and potentially observable by our experiment. Details of the experimental results and their implications to the phenomenon of GRB are presented. The experiment also enables us to place a 99% confidence level upper limit to the rate of explosions of primordial black holes (Hawking process) in the vicinity of the solar system at a value of 1600 or 5700/yr per cu pc, depending on whether the explosions take place according to an elementary or a composite particle hypothesis, respectively.

  8. Background Information: Deciphering Gamma Ray Burst Physics With Radio Telescopes

    NASA Astrophysics Data System (ADS)

    For 30 years, Gamma Ray Bursts, now known to be the most energetic explosions in the sky, have intrigued scientists and constituted one of the greatest mysteries in astrophysics. Such basic details as their exact locations in the sky and their distances from Earth remained unknown or subject to intense debate until just last year. With the discovery of "afterglows" at X-ray, visible, infrared and radio wavelengths, scientists have been able to study the physics of these explosive fireballs for the first time. Radio telescopes, the NSF's VLA in particular, are vitally important in this quest for the answers about Gamma Ray Bursts. Planned improvements to the VLA will make it an even more valuable tool in this field. Since their first identification in 1967 by satellites orbited to monitor compliance with the atmospheric nuclear test ban, more than 2,000 Gamma Ray Bursts have been detected. The celestial positions of the bursts have only been well-localized since early 1997, when the Italian- Dutch satellite Beppo-SAX went into operation. Since Beppo-SAX began providing improved information on burst positions, other instruments, both orbiting and ground-based, have been able to study the afterglows. So far, X-ray afterglows have been seen in about a dozen bursts, visible-light afterglows in six and radio afterglows in three. The search for radio emission from Gamma Ray Bursts has been an ongoing, target-of-opportunity program at the VLA for more than four years, led by NRAO scientist Dale Frail. The detection of afterglows "opens up a new era in the studies of Gamma Ray Bursts," Princeton University theorist Bohdan Paczynski wrote in a recent scientific paper. Optical studies of GRB 970508 indicated a distance of at least seven billion light-years, the first distance measured for a Gamma Ray Burst. VLA studies of the same burst showed that the fireball was about a tenth of a light-year in diameter a few days after the explosion and that it was expanding at very

  9. 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.

  10. 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.

  11. 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.

  12. The RHESSI Satellite and Classes of Gamma-ray Bursts

    SciTech Connect

    Ripa, Jakub; Meszaros, Attila; Hudec, Rene; Wigger, Claudia; Hajdas, Wojtek

    2008-05-22

    Some articles based on the BATSE gamma-ray burst (GRB) catalog claim the existence of a third population of GRBs, besides long and short. In this contribution we wanted to verify these claims with an independent data source, namely the RHESSI GRB catalog. Our verification is based on the statistical analysis of duration and hardness ratio of GRBs. The result is that there is no significant third group of GRBs in our RHESSI GRB data-set.

  13. High energy neutrinos from gamma-ray burst fireballs

    NASA Astrophysics Data System (ADS)

    Tamborra, Irene

    2016-05-01

    The diffuse high-energy neutrino emission from long and short gamma-ray bursts (GRBs) is studied within the fireball emission model. By requiring that the GRB high-energy neutrino counterparts follow up-to-date gamma-ray luminosity functions and redshift evolutions, we find that GRBs could contribute up to a few percents to the observed IceCube high-energy neutrino flux for sub-PeV energies, if the latter has a diffuse origin. Our findings suggest that larger exposure is mandatory to detect neutrinos from GRBs in future stacking searches.

  14. 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.

  15. 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.

  16. 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.; Parsons, A. M.; Sato, G.; Stamatikos, M.; Tueller, J.; Ukwatta, T. N.; Zhang, B.

    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.

  17. 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.

  18. Are Ultra-long Gamma-Ray Bursts Different?

    NASA Astrophysics Data System (ADS)

    Boër, M.; Gendre, B.; Stratta, G.

    2015-02-01

    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.

  19. 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.

  20. 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.

  1. Gamma ray burst optical counterpart search experiment (GROCSE)

    SciTech Connect

    Park, Hye-Sook; Ables, Elden; Bionta, Richard M.; Ott, Linda; Parker, Eric; Akerlof, Carl; Lee, Brian; Wallace, Scott; Barthelmy, Scott; Butterworth, Paul; Cline, Thomas; Gehrels, Neil; Fishman, Gerald; Kouveliotou, Chryssa; Meegan, Charles; Ferguson, Donald

    1996-08-01

    GROCSE (Gamma-Ray Optical Counterpart Search Experiment) 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 I, is sensitive down to M{sub V}{approx}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 M{sub V}{approx}14 with a 5 second exposure. GROCSE II 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 2Kx2K 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 17.6x17.6 deg. GROCSE II will be operating by the end of 1995. In this paper, we present an overview of the GROCSE system and the results of measurements with a GROCSE II prototype unit.

  2. 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.

  3. LINKING SHORT GAMMA-RAY BURSTS AND THEIR HOST GALAXIES

    SciTech Connect

    Rhoads, James E.

    2010-02-01

    The luminosities of short-duration gamma-ray burst (SGRB) host galaxies appear to be anticorrelated with both the isotropic equivalent gamma-ray energy and the gamma-ray luminosity of the explosions, based on a sample of 12 bursts with host galaxy redshifts and photometry. The correlation does depend on the correct identification of the GRB 050509b host, but is otherwise robust. In particular, simple observational selection effects only strengthen the statistical significance of this correlation, from approx95% to approx99%. The correlation may indicate that there are two physically distinct groups of SGRBs. If so, it requires that the more luminous class of explosions be associated with the younger class of progenitors. Alternatively, it could be due to a continuous distribution of burst and host properties, in which case it could be used as a crude SGRB distance indicator. As one possible explanation, we find that the effect of binary neutron star masses on inspiral time and energy reservoir produces a correlation of the appropriate sign, but does not automatically reproduce the correlation slope or the full range of SGRB energy scales. If confirmed by larger samples, this correlation will provide a valuable new constraint on SGRB progenitor models.

  4. 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.

  5. A Search for Simultaneous Optical Counterparts of Gamma-Ray Bursts (LOTIS: Livermore Optical Transient Imaging System)

    NASA Technical Reports Server (NTRS)

    Park, H.-S.

    1999-01-01

    Under this grant the UC Berkeley PI, K. Hurley, joined the LOTIS collaboration. His task was to provide precise localization data on cosmic gamma-ray bursts, so that the LOTIS automated camera data could be searched more efficiently for evidence of optical emission from gamma-ray burst sources. This was accomplished. A program is now in place which automatically sends Interplanetary Network data on bursts via e-mail to H.S. Park, for every burst detected by the GRB experiment aboard the Ulysses spacecraft (for which K. Hurley is the P.I.). The data consist either of triangulation annuli (obtained when just two spacecraft observe the burst) or error boxes (when three widely separated spacecraft observe it). These define a locus of possible burst positions. The annuli intersect the large error circles of the CGRO-BATSE experiment, and reduce their areas by a factor of approximately 25 or more. The error boxes reduce the areas by factors of several hundred. This in turn reduces the area which must be searched for an optical counterpart. No such counterparts have been observed to date by the LOTIS experiment, but several interesting upper limits have been obtained.

  6. New Results on Soft Gamma Repeaters and Gamma-Ray Bursts with INTEGRAL

    NASA Astrophysics Data System (ADS)

    Hurley, K.

    2005-12-01

    INTEGRAL has proven to be an excellent mission for the study of bursts, with speed, accuracy, and sensitivity rivalling those of Swift. Gamma-ray bursts are detected both within the IBIS field of view at a rate of about 10/year, and by the SPI anticoincidence system at a rate of about 100/year, as well as by the SPI. Hundreds of SGR bursts have been detected from SGR1806-20 by IBIS during Galactic center observations and ToO pointings. I will review some of the highlights of these observations, which include the closest securely identified GRB (z=0.105) after 980425/SN1998bw, and the discovery of a hardness-intensity anticorrelation for SGR bursts. I will also mention some of the more exotic possibilities offered by INTEGRAL, such as the measurement of GRB polarization and the study of quantum gravity using bursts. This work was supported by NASA INTEGRAL Guest Investigator program grants.

  7. The BATSE Gamma-Ray Burst Spectral Catalog. 1; High Time Resolution Spectroscopy of Bright Bursts Using High Energy Resolution Data

    NASA Technical Reports Server (NTRS)

    Preece, Robert D.; Briggs, Michael S.; Mallozzi, Robert S.; Pendleton, Geoffrey N.; Paciesas, W. S.; Band, David L.

    1999-01-01

    This is the first in a series of gamma-ray burst spectroscopy catalogs from the Burst And Transient Source Experiment (BATSE) on the Compton Gamma Ray Abstract: Observatory, each covering a different aspect of burst phenomenology. In this paper, we present time-sequences of spectral fit parameters for 156 bursts selected either for their high peak flux or fluence.

  8. Gamma -bursts by primordial Black Holes

    NASA Astrophysics Data System (ADS)

    Gaina, Alex

    Gamma-burts may arise as a result of quantum generation of photons (as well as neutrinos, gravitons, electrons) by Primordial Black Holes (PBH's) of mass 5-7 x 10^14 g (Hawking: Nature, Volume 248, Issue 5443, pp. 30-31, 1974,Communications in Mathematical Physics, Volume 43, Issue 3, pp.199-220; Page:Particle emission rates from a black hole: Massless particles from an uncharged, nonrotating hole, Phys. Rev. D 13, 198, 1976,Physical Review D - Particles and Fields, 3rd Series, vol. 14, Dec. 15, 1976, p. 3260-327, Particle emission rates from a black hole. III. Charged leptons from a nonrotating hole Phys. Rev. D 16, 2402 Published 15 October 1977; Jane Mac Gibbon, Quark- and gluon-jet emission from primordial black holes. II. The emission over the black-hole lifetime Phys. Rev. D 44, 376 - Published 15 July 1991, J.H. MacGibbon & B.J. Carr,Astrophysical Journal, Part 1, vol. 371, April 20, 1991, p. 447-469 ). Another way of the Gamma-rays production by highly rotating PBH's results from the bomb-like accumulation of mass bosons on superradiative bound levels, which I have called Bose instability in Black Holes (Ternov et al.Soviet Physics Journal, Volume 21, Issue 9, pp.1200-1204 1978; Detweiler: Physical Review D (Particles and Fields), Volume 22, Issue 10, 15 November 1980, pp.2323-2326 1980; Gaina and Ternov: Soviet Astronomy Letters, vol. 12, Nov.-Dec. 1986, p. 394-396; Gaina: Soviet Astronomy Letters, Vol.15, NO.3/MAY,JUN, P. 243, 1989,Astronomical and Astrophysical Transactions, vol. 10, Issue 2, pp.111-112, 1996,Bulletin Astronomique de Belgrade, No. 153, p. 29 - 34 ). The only type of black Holes which is still undiscovered is just the primordial Black Holes type. Is this a technical problem related wuith the sensitivity of Gamma-detectors or this is rather a problem of unfinalized of the quantum mechanical treatment of the Black Holes evaporation? Is this a problem related with inexactitudes of measurements of the Hubble constant or the primordial black

  9. 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.

  10. 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.

  11. Cosmic ray albedo gamma rays from the quiet sun

    NASA Technical Reports Server (NTRS)

    Seckel, D.; Stanev, T.; Gaisser, T. K.

    1992-01-01

    We estimate the flux of gamma-rays that result from collisions of high energy galactic cosmic rays with the solar atmosphere. An important aspect of our model is the propagation of cosmic rays through the magnetic fields of the inner solar systems. We use diffusion to model propagation down to the bottom of the corona. Below the corona we trace particle orbits through the photospheric fields to determine the location of cosmic ray interactions in the solar atmosphere and evolve the resultant cascades. For our nominal choice of parameters, we predict an integrated flux of gamma rays (at 1 AU) of F(E(sub gamma) greater than 100 MeV) approximately = 5 x 10(exp -8)/sq cm sec. This can be an order of magnitude above the galactic background and should be observable by the Energetic Gamma Ray experiment telescope (EGRET).

  12. Gravitational wave bursts from cosmic (super)strings: Quantitative analysis and constraints

    SciTech Connect

    Siemens, Xavier; Creighton, Jolien; Majumder, Saikat Ray; Cannon, Kipp; Read, Jocelyn; Maor, Irit

    2006-05-15

    We discuss data analysis techniques that can be used in the search for gravitational wave bursts from cosmic strings. When data from multiple interferometers are available, we describe consistency checks that can be used to greatly reduce the false alarm rates. We construct an expression for the rate of bursts for arbitrary cosmic string loop distributions and apply it to simple known solutions. The cosmology is solved exactly and includes the effects of a late-time acceleration. We find substantially lower burst rates than previous estimates suggest and explain the disagreement. Initial LIGO is unlikely to detect field-theoretic cosmic strings with the usual loop sizes, though it may detect cosmic superstrings as well as cosmic strings and superstrings with nonstandard loop sizes (which may be more realistic). In the absence of a detection, we show how to set upper limits based on the loudest event. Using Initial LIGO sensitivity curves, we show that these upper limits may result in interesting constraints on the parameter space of theories that lead to the production of cosmic strings.

  13. Radiation burst from a single {gamma}-photon field

    SciTech Connect

    Shakhmuratov, R. N.; Vagizov, F.; Kocharovskaya, O.

    2011-10-15

    The radiation burst from a single {gamma}-photon field interacting with a dense resonant absorber is studied theoretically and experimentally. This effect was discovered for the fist time by P. Helisto et al.[Phys. Rev. Lett. 66, 2037 (1991)] and it was named the ''gamma echo''. The echo is generated by a 180 Degree-Sign phase shift of the incident radiation field, attained by an abrupt change of the position of the absorber with respect to the radiation source during the coherence time of the photon wave packet. Three distinguishing cases of the gamma echo are considered; i.e., the photon is in exact resonance with the absorber, close to resonance (on the slope of the absorption line), and far from resonance (on the far wings of the resonance line). In resonance the amplitude of the radiation burst is two times larger than the amplitude of the input radiation field just before its phase shift. This burst was explained by Helisto et al. as a result of constructive interference of the coherently scattered field with the phase-shifted input field, both having almost the same amplitude. We found that out of resonance the scattered radiation field acquires an additional component with almost the same amplitude as the amplitude of the incident radiation field. The phase of the additional field depends on the optical thickness of the absorber and resonant detuning. Far from resonance this field interferes destructively with the phase-shifted incident radiation field and radiation quenching is observed. Close to resonance the three fields interfere constructively and the amplitude of the radiation burst is three times larger than the amplitude of the input radiation field.

  14. The Swift Gamma-Ray Burst Host Galaxy Legacy Survey. I. Sample Selection and Redshift Distribution

    NASA Astrophysics Data System (ADS)

    Perley, D. A.; Krühler, T.; Schulze, S.; de Ugarte Postigo, A.; Hjorth, J.; Berger, E.; Cenko, S. B.; Chary, R.; Cucchiara, A.; Ellis, R.; Fong, W.; Fynbo, J. P. U.; Gorosabel, J.; Greiner, J.; Jakobsson, P.; Kim, S.; Laskar, T.; Levan, A. J.; Michałowski, M. J.; Milvang-Jensen, B.; Tanvir, N. R.; Thöne, C. C.; Wiersema, K.

    2016-01-01

    We introduce the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (“SHOALS”), a multi-observatory high-redshift galaxy survey targeting the largest unbiased sample of long-duration gamma-ray burst (GRB) hosts yet assembled (119 in total). We describe the motivations of the survey and the development of our selection criteria, including an assessment of the impact of various observability metrics on the success rate of afterglow-based redshift measurement. We briefly outline our host galaxy observational program, consisting of deep Spitzer/IRAC imaging of every field supplemented by similarly deep, multicolor optical/near-IR photometry, plus spectroscopy of events without preexisting redshifts. Our optimized selection cuts combined with host galaxy follow-up have so far enabled redshift measurements for 110 targets (92%) and placed upper limits on all but one of the remainder. About 20% of GRBs in the sample are heavily dust obscured, and at most 2% originate from z\\gt 5.5. Using this sample, we estimate the redshift-dependent GRB rate density, showing it to peak at z∼ 2.5 and fall by at least an order of magnitude toward low (z = 0) redshift, while declining more gradually toward high (z∼ 7) redshift. This behavior is consistent with a progenitor whose formation efficiency varies modestly over cosmic history. Our survey will permit the most detailed examination to date of the connection between the GRB host population and general star-forming galaxies, directly measure evolution in the host population over cosmic time and discern its causes, and provide new constraints on the fraction of cosmic star formation occurring in undetectable galaxies at all redshifts.

  15. 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.

  16. Choked Jets and Low-Luminosity Gamma-Ray Bursts as Hidden Neutrino Sources

    NASA Astrophysics Data System (ADS)

    Senno, Nicholas; Murase, Kohta; Mészáros, Peter

    2016-03-01

    I will discuss choked gamma-ray burst (GRB) jets as possible sources of very high-energy (VHE) cosmic neutrinos. The jet propagation physics and radiation constraints are taken into account. We find that efficient shock acceleration of cosmic rays inside a high density stellar environment is possible for sufficiently low-powered jets and/or jets buried in an extended optically think envelope. Such conditions are favorable also for the GRB jets to become stalled. Such choked jets may explain transrelativistic SNe or low-luminosity GRBs by launching quasi-spherical shocks that breakout in the optically thick wind. Focusing on this possibility, we calculate the resulting diffuse neutrino spectra using the latest results of the local llGRB rate and luminosity function. We confirm that llGRBs can potentially give a significant contribution to the measured neutrino flux. The results are compatible with the IceCube (IC) data around 10-100 TeV without contradicting other IC limits on classical GRBs. Choked and llGRBs are dark in GeV-TeV gamma rays, and do not contribute significantly to the Fermi diffuse gamma-ray background. Precursor TeV neutrinos emerging prior to the shock breakout emission can be used as smoking gun evidence for a choked jet model for llGRBs.

  17. 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.

  18. Intergalactic shock acceleration and the cosmic gamma-ray background

    NASA Astrophysics Data System (ADS)

    Miniati, Francesco

    2002-11-01

    We investigate numerically the contribution to the cosmic gamma-ray background from cosmic-ray ions and electrons accelerated at intergalactic shocks associated with cosmological structure formation. We show that the kinetic energy of accretion flows in the low-redshift intergalactic medium is thermalized primarily through moderately strong shocks, which allow for an efficient conversion of shock ram pressure into cosmic-ray pressure. Cosmic rays accelerated at these shocks produce a diffuse gamma-ray flux which is dominated by inverse Compton emission from electrons scattering off cosmic microwave background photons. Decay of neutral π mesons generated in p-p inelastic collisions of the ionic cosmic-ray component with the thermal gas contribute about 30 per cent of the computed emission. Based on experimental upper limits on the photon flux above 100 MeV from nearby clusters we constrain the efficiency of conversion of shock ram pressure into relativistic CR electrons to <~1 per cent. Thus, we find that cosmic rays of cosmological origin can generate an overall significant fraction of order 20 per cent and no more than 30 per cent of the measured gamma-ray background.

  19. Search with VERITAS and SGARFACE for bursts of gamma-rays with energy greater than 100 MeV and with duration shorter than 15 μs

    NASA Astrophysics Data System (ADS)

    Schroedter, Martin

    2009-05-01

    Bursts of gamma rays above 100 MeV and with duration less than 15 μs might be produced by pulsars (Lyutikov, 2007), by explosions of primordial black holes (Hawking, 1974), or via some as-yet undiscovered mechanism, for example during gamma-ray bursts. Bursts of nearly simultaneous gamma-rays above 100 MeV can be detected by their Cherenkov radiation using ground-based telescopes. SGARFACE piggy-backs on the Whipple 10 m imaging air-Cherenkov telescope to search for bursts of gamma-rays with duration less than 15 μs. To eliminate cosmic- ray background events that mimic the expected image parameters of bursts, we search for correlations with VERITAS. VERITAS is the most sensitive array of air-Cherenkov telescopes in the northern hemisphere and is located about 7 km distant from the SGARFACE experiment. The fluence sensitivity of this search is 0.2 (0.01) photons/m^2 for 1 (10) GeV gamma-rays during a 100 ns burst. About 80 hours of observations have been taken with both instruments pointed at the same source in the sky. We present results of the search for bursts produced by the Crab pulsar, by GRBs, and by the explosion of primordial black holes.

  20. 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.

  1. Swift: The Next-Generation Gamma-Ray Burst Mission

    NASA Astrophysics Data System (ADS)

    Cline, Thomas; Gehrels, Neil; Norris, Jay

    2006-02-01

    Swift is a next-generation, multi-wavelength observatory for transient gamma-ray astromomy. A NASA mission with an international collaboration, Swift is in development for launch in 2004. It is designed to make breakthroughs in determining the origin of gamma-ray bursts (GRBs) and in using GRBs to probe the early Universe. This mission features a wide-field, 15-150 keV, gamma ray imager that will detect over 100 GRBs per year of all durations and spectral types, including X-ray rich, and localize them with better than 4 arc-minute accuracy. Autonomous, on-board source localization will enable rapid reorientation of two narrow-field optical/UV and X-ray telescopes to determine arc-second source localizations and to perform optical, UV, and x-ray spectrophotometry. A strong outreach program and the afterglow campaigns should make possible great advances in the understanding of the early Universe.

  2. 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.

  3. 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.

  4. The duration distribution of Swift Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Horváth, I.; Tóth, B. G.

    2016-05-01

    Decades ago two classes of gamma-ray bursts were identified and delineated as having durations shorter and longer than about 2 s. Subsequently indications also supported the existence of a third class. Using maximum likelihood estimation we analyze the duration distribution of 888 Swift BAT bursts observed before October 2015. Fitting three log-normal functions to the duration distribution of the bursts provides a better fit than two log-normal distributions, with 99.9999% significance. Similarly to earlier results, we found that a fourth component is not needed. The relative frequencies of the distribution of the groups are 8% for short, 35% for intermediate and 57% for long bursts which correspond to our previous results. We analyse the redshift distribution for the 269 GRBs of the 888 GRBs with known redshift. We find no evidence for the previously suggested difference between the long and intermediate GRBs' redshift distribution. The observed redshift distribution of the 20 short GRBs differs with high significance from the distributions of the other groups.

  5. The Error Distribution of BATSE Gamma-Ray Burst Locations

    NASA Technical Reports Server (NTRS)

    Briggs, Michael S.; Pendleton, Geoffrey N.; Kippen, R. Marc; Brainerd, J. J.; Hurley, Kevin; Connaughton, Valerie; Meegan, Charles A.

    1999-01-01

    Empirical probability models for BATSE gamma-ray burst (GRB) location errors are developed via a Bayesian analysis of the separations between BATSE GRB locations and locations obtained with the Interplanetary Network (IPN). Models are compared and their parameters estimated using 392 GRBs with single IPN annuli and 19 GRBs with intersecting IPN annuli. Most of the analysis is for the 4Br BATSE catalog; earlier catalogs are also analyzed. The simplest model that provides a good representation of the error distribution has 78% of the probability in a "core" term with a systematic error of 1.85 deg and the remainder in an extended tail with a systematic error of 5.1 deg, which implies a 68% confidence radius for bursts with negligible statistical uncertainties of 2.2 deg. There is evidence for a more complicated model in which the error distribution depends on the BATSE data type that was used to obtain the location. Bright bursts are typically located using the CONT data type, and according to the more complicated model, the 68% confidence radius for CONT-located bursts with negligible statistical uncertainties is 2.0 deg.

  6. The Second SWIFT Burst Alert Telescope (BAT) Gamma-Ray Burst Catalog

    NASA Technical Reports Server (NTRS)

    Sakamoto, T.; 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.; Stamatikos, M.; Tueller, J.; Ukwatta, T. N.; Zhang, B.

    2012-01-01

    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 parameters 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 T(sub 90) and T(sub 50) 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.

  7. 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

  8. The effect of extra dimensions on gravity wave bursts from cosmic string cusps

    SciTech Connect

    O'Callaghan, Eimear; Gregory, Ruth; Chadburn, Sarah; Geshnizjani, Ghazal; Zavala, Ivonne E-mail: ggeshnizjani@perimeterinstitute.ca E-mail: zavala@th.physik.uni-bonn.de

    2010-09-01

    We explore the kinematical effect of having extra dimensions on the gravitational wave emission from cosmic strings. Additional dimensions both round off cusps, and reduce the probability of their formation. We recompute the gravitational wave burst, taking into account these two factors, and find a potentially significant damping on the gravitational waves of the strings.

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

    1981-04-01

    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.

  12. 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.

  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. Interpretation of gamma-ray burst source count statistics

    NASA Technical Reports Server (NTRS)

    Petrosian, Vahe

    1993-01-01

    Ever since the discovery of gamma-ray bursts, the so-called log N-log S relation has been used for determination of their distances and distribution. This task has not been straightforward because of varying thresholds for the detection of bursts. Most of the current analyses of these data are couched in terms of ambiguous distributions, such as the distribution of Cp/Clim, the ratio of peak to threshold photon count rates, or the distribution of V/Vmax = (Cp/Clim) exp -3/2. It is shown that these distributions are not always a true reflection of the log N-log S relation. Some kind of deconvolution is required for obtaining the true log N-log S. Therefore, care is required in the interpretation of results of such analyses. A new method of analysis of these data is described, whereby the bivariate distribution of Cp and Clim is obtained directly from the data.

  15. SELECTION EFFECTS ON THE OBSERVED REDSHIFT DEPENDENCE OF GAMMA-RAY BURST JET OPENING ANGLES

    SciTech Connect

    Lu Ruijing; Wei Junjie; Liang Enwei; Qin Shufu

    2012-02-01

    An apparent redshift dependence of the jet opening angles ({theta}{sub j}) of gamma-ray bursts (GRBs) is observed from the current GRB sample. We investigate whether this dependence can be explained with instrumental selection effects and observational biases by a bootstrapping method. Assuming that (1) the GRB rate follows the star formation history and the cosmic metallicity history and (2) the intrinsic distributions of the jet-corrected luminosity (L{sub {gamma}}) and {theta}{sub j} are a Gaussian or a power-law function, we generate a mock Swift/Burst Alert Telescope (BAT) sample by considering various instrumental selection effects, including the flux threshold and the trigger probability of BAT, the probabilities of a GRB jet pointing to the instrument solid angle, and the probability of redshift measurement. Our results reproduce the observed {theta}{sub j} - z dependence well. We find that in the case of L{sub {gamma}}{proportional_to}{theta}{sup 2}{sub j} good consistency between the mock and observed samples can be obtained, indicating that both L{sub {gamma}} and {theta}{sub j} are degenerate for a flux-limited sample. The parameter set (L{sub {gamma}}, {theta}{sub j}) = (4.9 Multiplication-Sign 10{sup 49} erg s{sup -1}, 0.054 rad) gives the best consistency for the current Swift GRB sample. Considering the beaming effect, the derived intrinsic local GRB rate is accordingly 2.85 Multiplication-Sign 10{sup 2} Gpc{sup -3} yr{sup -1}, inferring that {approx}0.59% of Type Ib/c supernovae may be accompanied by a GRB.

  16. A POSSIBLE CONNECTION BETWEEN FAST RADIO BURSTS AND GAMMA-RAY BURSTS

    SciTech Connect

    Zhang, Bing

    2014-01-10

    The physical nature of fast radio bursts (FRBs), a new type of cosmological transient discovered recently, is not known. It has been suggested that FRBs can be produced when a spinning supra-massive neutron star loses centrifugal support and collapses to a black hole. Here, we suggest that such implosions can happen in supra-massive neutron stars shortly (hundreds to thousands of seconds) after their births, and an observational signature of such implosions may have been observed in the X-ray afterglows of some long and short gamma-ray bursts (GRBs). Within this picture, a small fraction of FRBs would be physically connected to GRBs. We discuss possible multi-wavelength electromagnetic signals and gravitational wave signals that might be associated with FRBs, and propose an observational campaign to unveil the physical nature of FRBs. In particular, we strongly encourage a rapid radio follow-up observation of GRBs starting from 100 s after a GRB trigger.

  17. 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.

  18. Experimental detection of an ELF radio pulse associated with the gamma-ray burst of December 27, 2004

    NASA Astrophysics Data System (ADS)

    Nickolaenko, A. P.; Schekotov, A. Yu.

    2011-06-01

    We compare the experimentally observed and model waveforms of the electromagnetic pulse associated with an abrupt change in the height of the Earth-ionosphere cavity, which was caused by an intense gamma-ray burst that arrived from the cosmic source in December 27, 2004. Polarization and spectral properties of the burst are examined. It is shown that the experimentally observed extremely low frequency (ELF) radio pulse exceeds the level of a regular Schumann-resonance background signal severalfold, and its waveform is close to the calculated one. The wave arrival angle is close to the direction towards the epicenter of the ionospheric disturbance. The time of pulse arrival at the Karymshino observatory (52.83°N, 158.13°E) is about 0.16 s ahead of the burst recording time.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Ninteenth International Cosmic Ray Conference. OG Sessions, Volume 1

    NASA Technical Reports Server (NTRS)

    Jones, F. C. (Compiler)

    1985-01-01

    Contributed papers addressing cosmic ray origin and galactic phenomena are compiled. The topic areas covered in this volume include gamma ray bursts, gamma rays from point sources, and diffuse gamma ray emission.

  4. 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.

  5. Gamma-Ray Bursts as seen by the Fermi Gamma-Ray Space Telescope

    SciTech Connect

    Omodei, Nicola

    2009-04-08

    The Large Area Telescope (LAT) instrument on the Fermi mission is revealing the rich spectral and temporal gamma-ray burst phenomena in the >100 MeV band. The synergy with Fermi's GBM detectors links these observations to those in the well-explored 10-1000 keV range; the addition of the >100 MeV band observations brings new hint and new information about burst emission in both the prompt and afterglow phases. In this contribution we describe the prospects for the Fermi Large Area Telescope (LAT) in observing Gamma-Ray Bursts (GRBs), and some preliminary results. Here we focus our attention on the importance of multi frequencies approach to GRB science during the just began Fermi era.

  6. 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.

  7. Gamma-Ray Bursts as Sources of Strong Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Granot, Jonathan; Piran, Tsvi; Bromberg, Omer; Racusin, Judith L.; Daigne, Frédéric

    2015-10-01

    Gamma-Ray Bursts (GRBs) are the strongest explosions in the Universe, which due to their extreme character likely involve some of the strongest magnetic fields in nature. This review discusses the possible roles of magnetic fields in GRBs, from their central engines, through the launching, acceleration and collimation of their ultra-relativistic jets, to the dissipation and particle acceleration that power their γ-ray emission, and the powerful blast wave they drive into the surrounding medium that generates their long-lived afterglow emission. An emphasis is put on particular areas in which there have been interesting developments in recent years.

  8. 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.

  9. Cyclotron scattering lines in gamma-ray burst spectra

    NASA Technical Reports Server (NTRS)

    Harding, Alice K.; Preece, Robert D.

    1989-01-01

    If cyclotron scattering, rather than absorption, is responsible for the line features observed recently in two gamma-ray burst spectra (Murakami et al., 1988), then the second and higher harmonics are due to resonant scattering events that excite the electron to Landau levels above the ground state. Here, relativistic Compton scattering cross sections are used to estimate the expected ratio of third to second harmonics in the presence of Doppler broadening. At the field strength (1.7 TG) required to give first and second harmonics at 19 keV and 38 keV, there should be no detectable third harmonic in the spectrum.

  10. 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.

  11. Light speed variation from gamma ray burst GRB 160509A

    NASA Astrophysics Data System (ADS)

    Xu, Haowei; Ma, Bo-Qiang

    2016-09-01

    It is postulated in Einstein's relativity that the speed of light in vacuum is a constant for all observers. However, the effect of quantum gravity could bring an energy dependence of light speed. Even a tiny speed variation, when amplified by the cosmological distance, may be revealed by the observed time lags between photons with different energies from astrophysical sources. From the newly detected long gamma ray burst GRB 160509A, we find evidence to support the prediction for a linear form modification of light speed in cosmological space.

  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. 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.

  14. 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.

  15. 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.

  16. Gamma Ray Burst with a delayed Supernovae explosion

    NASA Astrophysics Data System (ADS)

    Fargion, Daniele

    2016-07-01

    The Gamma Ray Burst models didn't find yet an explanation of a few percent well known GRB-SN events. The puzzle is based on the difficulties to make twice an explosion in the same place by a single collapsing star.The possible presence of a persistent and precessing jet from a neutron star or a Black hole whose blazing to us is observed as a GRB cannot naturally explain the additional late Supernova explosion. We Show that there is a new simple and well based astrophysical configuration able to make both the GRB and the late Supernova-like explosion, solving the main puzzle of GRB-SN signature.

  17. Observations of a gamma-ray burst and other sources with a large-area, balloon-borne detector

    NASA Technical Reports Server (NTRS)

    Wilson, R. B.; Fishman, G. J.; Meegan, C. A.

    1982-01-01

    Observations of a weak cosmic gamma ray burst of integrated intensity 2 x 10 to the -6th erg/sq cm, two solar flare events, and pulsed emission profiles of A0535+26 and NP0532 are reported for several energy intervals in the energy range from 45 to 520 keV. The measurements were made with a NaI(Tl) detector array flown on a balloon to 4 g/sq cm residual atmosphere from Palestine, Texas, on October 6-8, 1980, for 28 hours. The detector is a prototype of the Burst and Transient Source Experiment (BATSE) to be flown on the Gamma-Ray Observatory (GRO).

  18. The Energetic Transient Array ETA - A network of 'space buoys' in solar orbit for observations of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Ricker, George R.

    1990-01-01

    The Energetic Transient Array (ETA) is a concept for a dedicated interplanetary network of about 40 microsatellites ('space buoys') deployed in an about 1 AU radius solar orbit for the observation of cosmic gamma ray bursts (GRBs). Such a network is essential for the determination of highly accurate (about 0.1 arcsec) error boxes for GRBs. For each of about 100 bursts which would be detectable per year of observation by such a network, high resolution spectra could be obtained through the use of passively-cooled Ge gamma-ray detectors. Stabilization of each microsatellite would be achieved by a novel technique based on the radiation pressure exerted on 'featherable' solar paddles. It should be possible to have a fully functional array of satellites in place before the end of the decade for a total cost of about $20M, exclusive of launcher fees.

  19. 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.

  20. Chandra Contributes to ESA's Integral Detection of Closest Gamma-Ray Burst

    NASA Astrophysics Data System (ADS)

    2004-08-01

    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, and also the faintest. This also suggests that an entire population of sub-energetic gamma-ray bursts has so far gone unnoticed. 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 should emit similar amounts of gamma-ray energy. The fraction of it detected at Earth should then depend on the 'width' (opening angle) and orientation of the beam as well as on the distance. The energy received should be larger when the beam is narrow or points towards us and smaller when the beam is broad or points away from us. New data collected with ESA's high energy observatories, Integral and XMM-Newton, now show that this picture is not so clear-cut and that the amount of energy emitted by GRBs can vary significantly. "The idea that all GRBs spit out the same amount of gamma rays, or that they are 'standard candles' as we call them, is simply ruled out by the new data," said Dr Sergey Sazonov, from the Space Research Institute of the Russian Academy of Sciences, Moscow (Russia) and the Max-Planck Institute for Astrophysics, Garching near Munich (Germany). Sazonov and an international team of researchers studied the GRB detected by Integral on 3 December 2003 and given the code-name of GRB 031203. Within a record 18 seconds of the burst, the Integral Burst Alert System

  1. Gamma-Ray bursts: accumulating afterglow implications, progenitor clues, and prospects.

    PubMed

    Mészáros, P

    2001-01-01

    Gamma-ray bursts (GRBs) are sudden, intense flashes of gamma rays that, for a few blinding seconds, light up in an otherwise fairly dark gamma-ray sky. They are detected at the rate of about once a day, and while they are on, they outshine every other gamma-ray source in the sky, including the sun. Major advances have been made in the last 3 or 4 years, including the discovery of slowly fading x-ray, optical, and radio afterglows of GRBs, the identification of host galaxies at cosmological distances, and evidence showing that many GRBs are associated with star-forming regions and possibly supernovae. Progress has been made in understanding how the GRB and afterglow radiation arises in terms of a relativistic fireball shock model. These advances have opened new vistas and questions on the nature of the central engine, the identity of their progenitors, the effects of the environment, and their possible gravitational wave, cosmic ray, and neutrino luminosity. The debates on these issues indicate that GRBs remain among the most mysterious puzzles in astrophysics. PMID:11141551

  2. 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

  3. 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"

  4. Gamma-ray bursts: huge explosion in the early Universe.

    PubMed

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

    2006-03-01

    Long gamma-ray bursts (GRBs) are bright flashes of high-energy photons that can last for tens of minutes; they are generally associated with galaxies that have a high rate of star formation and probably arise from the collapsing cores of massive stars, which produce highly relativistic jets (collapsar model). Here we describe gamma- and X-ray observations of the most distant GRB ever observed (GRB 050904): its redshift (z) of 6.29 means that this explosion happened 12.8 billion years ago, corresponding to a time when the Universe was just 890 million years old, close to the reionization era. This means that not only did stars form in this short period of time after the Big Bang, but also that enough time had elapsed for them to evolve and collapse into black holes. PMID:16525462

  5. Search for optical bursts from gamma-ray bursters. I

    NASA Technical Reports Server (NTRS)

    Hudec, R.; Borovicka, J.; Wenzel, W.; Atteia, J.-L.; Barat, C.; Hurley, K.; Niel, M.; Cline, T.; Desai, U.; Teegarden, B.

    1987-01-01

    Preliminary results of an examination of the Ondrejov and Sonneberg plate collections for possible optical counterparts to gamma-ray bursters are presented. The investigation proceeds in three different directions: (1) time-correlated searches for gamma-ray bursts (GRB) with known positions, (2) time-correlated searches for GRB without know positions, and (3) archival searches. 3 GRB with known positions and 28 GRB without known positions were studied in this way; archival searches representing a total exposure of 2.75 yr were done for 10 GRB positions, with limiting magnitudes for a 1 s flash between 3 and 8. No evidence for true optical images associated with GRB was found. Some statistical conclusions are drawn and the results obtained are discussed.

  6. Searches for Gravitational Waves Associated with Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Hoak, Daniel; LIGO Scientific Collaboration, Virgo Collaboration

    2015-01-01

    The central engines of gamma-ray bursts (GRBs) are expected to be bright sources of gravitational waves. Over the past decade, coherent analysis techniques have been applied to search for gravitational-wave signals associated with GRBs, using data from the first generation of the LIGO and Virgo detectors. In these searches, no detection candidates were found, but upper limits were placed on the emission of gravitational waves from the GRB progenitors. The advanced LIGO and Virgo instruments are expected to begin operation in the next few years, and an extrapolation of upper limits from the first generation indicates that joint observations between gamma-ray satellites and gravitational-wave detectors is possible for certain progenitor models and event rates.

  7. Light speed variation from gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Xu, Haowei; Ma, Bo-Qiang

    2016-09-01

    The effect of quantum gravity can bring a tiny light speed variation which is detectable through energetic photons propagating from gamma ray bursts (GRBs) to an observer such as the space observatory. Through an analysis of the energetic photon data of the GRBs observed by the Fermi Gamma-ray Space Telescope (FGST), we reveal a surprising regularity of the observed time lags between photons of different energies with respect to the Lorentz violation factor due to the light speed energy dependence. Such regularity suggests a linear form correction of the light speed v(E) = c(1 - E /ELV) , where E is the photon energy and ELV =(3.60 ± 0.26) ×1017 GeV is the Lorentz violation scale measured by the energetic photon data of GRBs. The results support an energy dependence of the light speed in cosmological space.

  8. The Signature of an Anisotropic Distribution of Gamma-ray Bursts

    NASA Astrophysics Data System (ADS)

    Gan, Li-xiong; Zou, Yuan-chuan; Dai, Zi-gao

    2016-01-01

    Anomalies of the cosmic microwave background (CMB) map have been widely acquainted nowadays via the Wilkinson Microwave Anisotropy Probe (WMAP) satellite and the Planck satellite. One anomaly is the alignment of multipole moments from l = 2 to l = 5. In our work, we investigate the angular distribution of gamma-ray bursts (GRBs) to find whether there exists an anomaly similar to that of CMB. We perform the spherical-harmonic expansion on the GRB sample to derive the coefficients of a few foremost terms. It is found that a rough alignment of multipole moments from l = 2 to l = 4 exists, while the multipole moment of l = 5 points to a different direction. And that the quadrupole moment is obviously of planar distribution, while the other ones are normal.

  9. GAMMA-RAY BURST PROMPT EMISSION: JITTER RADIATION IN STOCHASTIC MAGNETIC FIELD REVISITED

    SciTech Connect

    Mao, Jirong; Wang Jiancheng

    2011-04-10

    We revisit the radiation mechanism of relativistic electrons in the stochastic magnetic field and apply it to the high-energy emissions of gamma-ray bursts (GRBs). We confirm that jitter radiation is a possible explanation for GRB prompt emission in the condition of a large electron deflection angle. In the turbulent scenario, the radiative spectral property of GRB prompt emission is decided by the kinetic energy spectrum of turbulence. The intensity of the random and small-scale magnetic field is determined by the viscous scale of the turbulent eddy. The microphysical parameters {epsilon}{sub e} and {epsilon}{sub B} can be obtained. The acceleration and cooling timescales are estimated as well. Due to particle acceleration in magnetized filamentary turbulence, the maximum energy released from the relativistic electrons can reach a value of about 10{sup 14} eV. The GeV GRBs are possible sources of high-energy cosmic-ray.

  10. Research in particles and fields. [cosmic rays, gamma rays, and cosmic plasma

    NASA Technical Reports Server (NTRS)

    Stone, E. C.; Buffington, A.; Davis, L., Jr.; Prince, T. A.; Vogt, R. E.

    1984-01-01

    Research activities in cosmic rays, gamma rays, and astrophysical plasmas are reviewed. Energetic particle and photon detector systems flown on spacecraft and balloons were used to carry out the investigations. Specific instruments mentioned are: the high energy isotope spectrometer telescope, the electron/isotope spectrometer, the heavy isotope spectrometer telescope, and magnetometers. Solar flares, planetary magnetospheres, element abundance, the isotopic composition of low energy cosmic rays, and heavy nuclei are among the topics receiving research attention.

  11. Remarks on the nature of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schmidt, Maarten

    1992-01-01

    We first recall that in radio astronomy, isotropy and source counts steeper than the Euclidean value of -1.5 provided early evidence for the cosmological nature of radio sources. We discuss briefly whether anything can be wrong with the evidence for isotropy and a nonuniform distribution of GRBs. We identify the selection of cosmic GRBs among recorded bursts and their isotropy as the weaker part of the evidence. We suggest a way to relate the various V/V(max) values to each other. We point out that the strong concentration of small V/V(max) values fits well with a uniform distribution of sources out to a redshift of about 2, but note that sources observed at these redshifts generally exhibit evolution, i.e., a nonuniform space distribution.

  12. Naked-Eye Gamma-ray Burst Model for GRB 080319B

    NASA Video Gallery

    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...

  13. Search for gravitational-wave bursts from soft gamma repeaters.

    PubMed

    Abbott, B; Abbott, R; Adhikari, R; Ajith, P; Allen, B; Allen, G; Amin, R; Anderson, S B; Anderson, W G; Arain, M A; Araya, M; Armandula, H; Armor, P; Aso, Y; Aston, S; Aufmuth, P; Aulbert, C; Babak, S; Ballmer, S; Bantilan, H; Barish, B C; Barker, C; Barker, D; Barr, B; Barriga, P; Barton, M A; Bartos, I; Bastarrika, M; Bayer, K; Betzwieser, J; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Biswas, R; Black, E; Blackburn, K; Blackburn, L; Blair, D; Bland, B; Bodiya, T P; Bogue, L; Bork, R; Boschi, V; Bose, S; Brady, P R; Braginsky, V B; Brau, J E; Brinkmann, M; Brooks, A; Brown, D A; Brunet, G; Bullington, A; Buonanno, A; Burmeister, O; Byer, R L; Cadonati, L; Cagnoli, G; Camp, J B; Cannizzo, J; Cannon, K; Cao, J; Cardenas, L; Casebolt, T; Castaldi, G; Cepeda, C; Chalkley, E; Charlton, P; Chatterji, S; Chelkowski, S; Chen, Y; Christensen, N; Clark, D; Clark, J; Cokelaer, T; Conte, R; Cook, D; Corbitt, T; Coyne, D; Creighton, J D E; Cumming, A; Cunningham, L; Cutler, R M; Dalrymple, J; Danzmann, K; Davies, G; Debra, D; Degallaix, J; Degree, M; Dergachev, V; Desai, S; Desalvo, R; Dhurandhar, S; Díaz, M; Dickson, J; Dietz, A; Donovan, F; Dooley, K L; Doomes, E E; Drever, R W P; Duke, I; Dumas, J-C; Dupuis, R J; Dwyer, J G; Echols, C; Effler, A; Ehrens, P; Espinoza, E; Etzel, T; Evans, T; Fairhurst, S; Fan, Y; Fazi, D; Fehrmann, H; Fejer, M M; Finn, L S; Flasch, K; Fotopoulos, N; Freise, A; Frey, R; Fricke, T; Fritschel, P; Frolov, V V; Fyffe, M; Garofoli, J; Gholami, I; Giaime, J A; Giampanis, S; Giardina, K D; Goda, K; Goetz, E; Goggin, L; González, G; Gossler, S; Gouaty, R; Grant, A; Gras, S; Gray, C; Gray, M; Greenhalgh, R J S; Gretarsson, A M; Grimaldi, F; Grosso, R; Grote, H; Grunewald, S; Guenther, M; Gustafson, E K; Gustafson, R; Hage, B; Hallam, J M; Hammer, D; Hanna, C; Hanson, J; Harms, J; Harry, G; Harstad, E; Hayama, K; Hayler, T; Heefner, J; Heng, I S; Hennessy, M; Heptonstall, A; Hewitson, M; Hild, S; Hirose, E; Hoak, D; Hosken, D; Hough, J; Huttner, S H; Ingram, D; Ito, M; Ivanov, A; Johnson, B; Johnson, W W; Jones, D I; Jones, G; Jones, R; Ju, L; Kalmus, P; Kalogera, V; Kamat, S; Kanner, J; Kasprzyk, D; Katsavounidis, E; Kawabe, K; Kawamura, S; Kawazoe, F; Kells, W; Keppel, D G; Khalili, F Ya; Khan, R; Khazanov, E; Kim, C; King, P; Kissel, J S; Klimenko, S; Kokeyama, K; Kondrashov, V; Kopparapu, R K; Kozak, D; Kozhevatov, I; Krishnan, B; Kwee, P; Lam, P K; Landry, M; Lang, M M; Lantz, B; Lazzarini, A; Lei, M; Leindecker, N; Leonhardt, V; Leonor, I; Libbrecht, K; Lin, H; Lindquist, P; Lockerbie, N A; Lodhia, D; Lormand, M; Lu, P; Lubinski, M; Lucianetti, A; Lück, H; Machenschalk, B; Macinnis, M; Mageswaran, M; Mailand, K; Mandic, V; Márka, S; Márka, Z; Markosyan, A; Markowitz, J; Maros, E; Martin, I; Martin, R M; Marx, J N; Mason, K; Matichard, F; Matone, L; Matzner, R; Mavalvala, N; McCarthy, R; McClelland, D E; McGuire, S C; McHugh, M; McIntyre, G; McIvor, G; McKechan, D; McKenzie, K; Meier, T; Melissinos, A; Mendell, G; Mercer, R A; Meshkov, S; Messenger, C J; Meyers, D; Miller, J; Minelli, J; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Miyakawa, O; Moe, B; Mohanty, S; Moreno, G; Mossavi, K; Mowlowry, C; Mueller, G; Mukherjee, S; Mukhopadhyay, H; Müller-Ebhardt, H; Munch, J; Murray, P; Myers, E; Myers, J; Nash, T; Nelson, J; Newton, G; Nishizawa, A; Numata, K; O'Dell, J; Ogin, G; O'Reilly, B; O'Shaughnessy, R; Ottaway, D J; Ottens, R S; Overmier, H; Owen, B J; Pan, Y; Pankow, C; Papa, M A; Parameshwaraiah, V; Patel, P; Pedraza, M; Penn, S; Perreca, A; Petrie, T; Pinto, I M; Pitkin, M; Pletsch, H J; Plissi, M V; Postiglione, F; Principe, M; Prix, R; Quetschke, V; Raab, F; Rabeling, D S; Radkins, H; Rainer, N; Rakhmanov, M; Ramsunder, M; Rehbein, H; Reid, S; Reitze, D H; Riesen, R; Riles, K; Rivera, B; Robertson, N A; Robinson, C; Robinson, E L; Roddy, S; Rodriguez, A; Rogan, A M; Rollins, J; Romano, J D; Romie, J; Route, R; Rowan, S; Rüdiger, A; Ruet, L; Russell, P; Ryan, K; Sakata, S; Samidi, M; de la Jordana, L Sancho; Sandberg, V; Sannibale, V; Saraf, S; Sarin, P; Sathyaprakash, B S; Sato, S; Saulson, P R; Savage, R; Savov, P; Schediwy, S W; Schilling, R; Schnabel, R; Schofield, R; Schutz, B F; Schwinberg, P; Scott, S M; Searle, A C; Sears, B; Seifert, F; Sellers, D; Sengupta, A S; Shawhan, P; Shoemaker, D H; Sibley, A; Siemens, X; Sigg, D; Sinha, S; Sintes, A M; Slagmolen, B J J; Slutsky, J; Smith, J R; Smith, M R; Smith, N D; Somiya, K; Sorazu, B; Stein, L C; Stochino, A; Stone, R; Strain, K A; Strom, D M; Stuver, A; Summerscales, T Z; Sun, K-X; Sung, M; Sutton, P J; Takahashi, H; Tanner, D B; Taylor, R; Taylor, R; Thacker, J; Thorne, K A; Thorne, K S; Thüring, A; Tokmakov, K V; Torres, C; Torrie, C; Traylor, G; Trias, M; Tyler, W; Ugolini, D; Ulmen, J; Urbanek, K; Vahlbruch, H; Van Den Broeck, C; van der Sluys, M; Vass, S; Vaulin, R; Vecchio, A; Veitch, J; Veitch, P; Villar, A; Vorvick, C; Vyachanin, S P; Waldman, S J; Wallace, L; Ward, H; Ward, R; Weinert, M; Weinstein, A; Weiss, R; Wen, S; Wette, K; Whelan, J T; Whitcomb, S E; Whiting, B F; Wilkinson, C; Willems, P A; Williams, H R; Williams, L; Willke, B; Wilmut, I; Winkler, W; Wipf, C C; Wiseman, A G; Woan, G; Wooley, R; Worden, J; Wu, W; Yakushin, I; Yamamoto, H; Yan, Z; Yoshida, S; Zanolin, M; Zhang, J; Zhang, L; Zhao, C; Zotov, N; Zucker, M; Zweizig, J; Barthelmy, S; Gehrels, N; Hurley, K C; Palmer, D

    2008-11-21

    We present a LIGO search for short-duration gravitational waves (GWs) associated with soft gamma ray repeater (SGR) bursts. This is the first search sensitive to neutron star f modes, usually considered the most efficient GW emitting modes. We find no evidence of GWs associated with any SGR burst in a sample consisting of the 27 Dec. 2004 giant flare from SGR 1806-20 and 190 lesser events from SGR 1806-20 and SGR 1900+14. The unprecedented sensitivity of the detectors allows us to set the most stringent limits on transient GW amplitudes published to date. We find upper limit estimates on the model-dependent isotropic GW emission energies (at a nominal distance of 10 kpc) between 3x10;{45} and 9x10;{52} erg depending on waveform type, detector antenna factors and noise characteristics at the time of the burst. These upper limits are within the theoretically predicted range of some SGR models. PMID:19113401

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

    SciTech Connect

    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.; Mersov, G.A.

    1981-04-15

    A gamma-ray burst was recorded on 1979 April 6 at 1140 UT by instruments on the Pioneer Venus Orbiter (PVO) Venera 11 (V11), Venera12 (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 (Mazets and Golenetskii), thus resembling the 1979 March 5 events (Mazets et al .; Cline et al .; Evans et al .; Brarat et al.) in two respects. However, important differences in rise time and spectral hardness prevent one from concluding positively that the two events shared the same mechanism or had comparable energetics. Using arrival time analysis we have obtained for the April 6 burst a <1/sub '/ diameter error box centered at (..cap alpha.., delta)/sub 1950/ = (23/sup h/11/sup m/12/sup s/,-49/sup 0/55'39''). According to our searches, there is no cataloged object within or suggestively close to this error box. A UK Schmidt plate of the region likewise revealed no images within the error box to m/sub v/ = 22.5. 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.

  15. The sharpness of gamma-ray burst prompt emission spectra

    NASA Astrophysics Data System (ADS)

    Yu, Hoi-Fung; van Eerten, Hendrik J.; Greiner, Jochen; Sari, Re'em; Narayana Bhat, P.; von Kienlin, Andreas; Paciesas, William S.; Preece, Robert D.

    2015-11-01

    Context. We study the sharpness of the time-resolved prompt emission spectra of gamma-ray bursts (GRBs) observed by the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Aims: We aim to obtain a measure of the curvature of time-resolved spectra that can be compared directly to theory. This tests the ability of models such as synchrotron emission to explain the peaks or breaks of GBM prompt emission spectra. Methods: We take the burst sample from the official Fermi GBM GRB time-resolved spectral catalog. We re-fit all spectra with a measured peak or break energy in the catalog best-fit models in various energy ranges, which cover the curvature around the spectral peak or break, resulting in a total of 1113 spectra being analyzed. We compute the sharpness angles under the peak or break of the triangle constructed under the model fit curves and compare them to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. Results: We find that 35% of the time-resolved spectra are inconsistent with the single-electron synchrotron function, and 91% are inconsistent with the Maxwellian synchrotron function. The single temperature, single emission time, and location blackbody function is found to be sharper than all the spectra. No general evolutionary trend of the sharpness angle is observed, neither per burst nor for the whole population. It is found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to % of the peak flux. Conclusions: Our results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed GRB prompt spectra. Because any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin

  16. 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

  17. 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

  18. 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.

  19. Effects of Goldstone bosons on gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Tu, Huitzu; Ng, Kin-Wang

    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.

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

    SciTech Connect

    Sagi, Eran; Nakar, Ehud

    2012-04-10

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

  1. 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.

  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. 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.

  4. Optical studies of gamma-ray bursts. 2: The superbowl burst GRB 930131

    NASA Technical Reports Server (NTRS)

    Mcnamara, Bernard; Harrison, Thomas E.

    1994-01-01

    We report Charge Couple Devices (CCD) observations of the central region of the Compton Telescope (COMPTEL) error box for the 31 Jan 1993 gamma-ray burst. One optical transient was found. Its distance from the IPN track and Energy Gamma Ray Experiment Telescope (EGRET) error box make the association of this object with GRB 930131 doubtful. We present new CCD observations of two objects identified by Schaefer et al. (1993) that are located within a few arcminutes of the interplanetary network (IPN) that were reported to be possibly variable. We also report observations on the ROSAT All-sky Survey Extreme Ultraviolet (EUV) source noted by those investigators and the RS CVn star HD 106255. The ROSAT All-Sky Survey EUV source is suggested to arise from a faint, but relatively rich cluster of galaxies. HD 106255 is located approximately 7 min from the IPN. Our CCD results show that this star was bluer than previously reported, but these observations were obtained significantly after the occurrence of GRB 930131. It is not possible to estimate the color of HD 106255 when the burst occurred.

  5. An absence of neutrinos associated with cosmic-ray acceleration in γ-ray bursts.

    PubMed

    2012-04-19

    Very energetic astrophysical events are required to accelerate cosmic rays to above 10(18) electronvolts. GRBs (γ-ray bursts) have been proposed as possible candidate sources. In the GRB 'fireball' model, cosmic-ray acceleration should be accompanied by neutrinos produced in the decay of charged pions created in interactions between the high-energy cosmic-ray protons and γ-rays. Previous searches for such neutrinos found none, but the constraints were weak because the sensitivity was at best approximately equal to the predicted flux. Here we report an upper limit on the flux of energetic neutrinos associated with GRBs that is at least a factor of 3.7 below the predictions. This implies either that GRBs are not the only sources of cosmic rays with energies exceeding 10(18) electronvolts or that the efficiency of neutrino production is much lower than has been predicted. PMID:22517161

  6. 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.

  7. Gamma-ray astronomy and the origin of cosmic rays

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1978-01-01

    New surveys of galactic gamma ray emission together with millimeter wave radio surveys indicated that cosmic rays were produced as the result of supernova explosions in our galaxy with the most intense production occurring in a Great Galactic Ring about 35,000 light years in diameter where supernova remnants and pulsars were concentrated.

  8. Gamma ray line production from cosmic ray spallation reactions

    NASA Technical Reports Server (NTRS)

    Silberberg, R.; Tsao, C. H.; Letaw, J. R.

    1985-01-01

    The gamma ray line intensities due to cosmic ray spallation reactions in clouds, the galactic disk and accreting binary pulsars are calculated. With the most favorable plausible assumptions, only a few lines may be detectable to the level of 0.0000001 per sq. cm per sec. The intensities are compared with those generated in nuclear excitation reactions.

  9. Propagation of Cosmic Rays and Diffuse Galactic Gamma Rays

    NASA Technical Reports Server (NTRS)

    Moskalenko, Igor V.

    2004-01-01

    This paper presents an introduction to the astrophysics of cosmic rays and diffuse gamma-rays and discusses some of the puzzles that have emerged recently due to more precise data and improved propagation models: the excesses in Galactic diffuse gamma-ray emission, secondary antiprotons and positrons, and the flatter than expected gradient of cosmic rays in the Galaxy. These also involve the dark matter, a challenge to modern physics, through its indirect searches in cosmic rays. Though the final solutions are yet to be found, I discuss some ideas and results obtained mostly with the numerical propagation model GALPROP. A fleet of spacecraft and balloon experiments targeting these specific issues is set to lift off in a few years, imparting a feeling of optimism that a new era of exciting discoveries is just around the corner. A complete and comprehensive discussion of all the recent results is not attempted here due to the space limitations.

  10. FERMI/Gamma-ray Burst Monitor upper limits assuming a magnetar origin for the repeating Fast Radio Burst source, FRB 121102

    NASA Astrophysics Data System (ADS)

    Younes, George; Kouveliotou, Chryssa; Huppenkothen, Daniela; Gogus, Ersin; Kaneko, Yuki; van der Horst, Alexander

    2016-03-01

    Spitler et al. (2016, 10.1038/nature17168) reported a repeating Fast Radio Burst source, FRB 121102, with a rate of about 3 bursts/hr. We searched the FERMI/Gamma-ray Burst Monitor (GBM) for possible gamma-ray counterparts for these events.

  11. Gamma-ray burst spectroscopy capabilities of the BATSE/GRO experiment

    NASA Technical Reports Server (NTRS)

    Matteson, J. L.; Fishman, G. J.; Meegan, C. A.; Parnell, T. A.; Wilson, R. B.; Paciesas, W.; Cline, T. L.; Teegarden, B. J.

    1985-01-01

    A scintillation spectrometer is included in each of the eight BATSE/GRO detector modules, resulting in all-sky coverage for gamma-ray bursts. The scientific motivation, design and capabilities of these spectrometers for performing spectral observations over a wide range of gamma-ray energies and burst intensities are described.

  12. A search for pre- and post-burst emission from well-localized gamma-ray burst locations

    NASA Technical Reports Server (NTRS)

    Emslie, A. Gordon

    1994-01-01

    We present the results from the first long-term search for nonburst gamma-ray emission from the positions of 70 intense, well-localized bursts. Using the BATSE occultation technique, designed for monitoring of discrete sources, these burst positions were measured in the energy range of approximately 15 keV to 1.8 MeV over a 112 day interval during 1991. None of these 70 locations exhibited detectable emission at or above the level of approximately 5 x 10(exp -9) ergs cm(exp -2) s(exp -1) during the 112 day interval. This level is approximately 1000 times less than the typical intensity of the burst associated with the given location. In addition, 35 intense gamma-ray bursts detected by BATSE were examined in a five day interval centered on the time of detection. We find no compelling evidence that these bursts emit preburst emission or display prompt postburst emission at a level of approximately 5 x 10(exp -9) ergs cm(exp 2) s(exp -1) on timescales of approximately 1 hr or longer. The lack of detectable long-term emission or preburst and postburst emission from the positions of gamma-ray bursts has important consequences for a variety of burst production models.

  13. 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. PMID:24237502

  14. Optical telescope BIRT in ORIGIN for gamma ray burst observing

    NASA Astrophysics Data System (ADS)

    Content, Robert; Sharples, Ray; Page, Mathew J.; Cole, Richard; Walton, David M.; Winter, Berend; Pedersen, Kristian; Hjorth, Jens; Andersen, Michael; Hornstrup, Allan; den Herder, Jan-Willem A.; Piro, Luigi

    2012-09-01

    The ORIGIN concept is a space mission with a gamma ray, an X-ray and an optical telescope to observe the gamma ray bursts at large Z to determine the composition and density of the intergalactic matter in the line of sight. It was an answer to the ESA M3 call for proposal. The optical telescope is a 0.7-m F/1 with a very small instrument box containing 3 instruments: a slitless spectrograph with a resolution of 20, a multi-imager giving images of a field in 4 bands simultaneously, and a cross-dispersed Échelle spectrograph giving a resolution of 1000. The wavelength range is 0.5 μm to 1.7 μm. All instruments fit together in a box of 80 mm x 80 mm x 200 mm. The low resolution spectrograph uses a very compact design including a special triplet. It contains only spherical surfaces except for one tilted cylindrical surface to disperse the light. To reduce the need for a high precision pointing, an Advanced Image Slicer was added in front of the high resolution spectrograph. This spectrograph uses a simple design with only one mirror for the collimator and another for the camera. The Imager contains dichroics to separate the bandwidths and glass thicknesses to compensate the differences in path length. All 3 instruments use the same 2k x 2k detector simultaneously so that telescope pointing and tip-tilt control of a fold mirror permit to place the gamma ray burst on the desired instrument without any other mechanism.

  15. Gamma rays and cosmic rays at Venus: The Pioneer Venus gamma ray detector and considerations for future measurements

    NASA Astrophysics Data System (ADS)

    Lorenz, Ralph D.; Lawrence, David J.

    2015-05-01

    We draw attention to, and present a summary archive of the data from, the Pioneer Venus Orbiter Gamma-ray Burst Detector (OGBD), an instrument not originally conceived with Venus science in mind. We consider the possibility of gamma-ray flashes generated by lightning and model the propagation of gamma rays in the Venusian atmosphere, finding that if gamma rays originate at the upper range of reported cloud top altitudes (75 km altitude), they may be attenuated by factors of only a few, whereas from 60 km altitude they are attenuated by over two orders of magnitude. The present archive is too heavily averaged to reliably detect such a source (and we appeal to investigators who may have retained a higher-resolution archive), but the data do provide a useful and unique record of the cosmic ray flux at Venus 1978-1993. We consider other applications of future orbital gamma ray data, such as atmospheric occultations and the detection of volcanic materials injected high in the atmosphere.

  16. Cosmic gamma-ray lines - Theory

    NASA Technical Reports Server (NTRS)

    Lingenfelter, R. E.; Ramaty, R.

    1980-01-01

    The various processes that lead to gamma-ray line emission and the possible astrophysical sources of such emission are reviewed. The processes of nuclear excitation, radiative capture, positron annihilation, and cyclotron radiation, which may produce gamma-ray line emission from such diverse sources as the interstellar medium, novas, supernovas, pulsars, accreting compact objects, the galactic nucleus and the nuclei of active galaxies are considered. The significance of the relative intensities, widths, and frequency shifts of the lines are also discussed. Particular emphasis is placed on understanding those gamma-ray lines that have already been observed from astrophysical sources.

  17. 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.

  18. Gamma-Ray, Cosmic Ray and Neutrino Tests of Lorentz Invariance and Quantum Gravity Models

    NASA Technical Reports Server (NTRS)

    Stecker, Floyd

    2011-01-01

    High-energy astrophysics observations provide the best possibilities to detect a very small violation of Lorentz invariance such as may be related to the structure of space-time near the Planck scale of approximately 10(exp -35) m. I will discuss here the possible signatures of Lorentz invariance violation (LIV) from observations of the spectra, polarization, and timing of gamma-rays from active galactic nuclei and gamma-ray bursts. Other sensitive tests are provided by observations of the spectra of ultrahigh energy cosmic rays and neutrinos. Using the latest data from the Pierre Auger Observatory one can already derive an upper limit of 4.5 x 10(exp -23) to the amount of LIV of at a proton Lorentz factor of approximately 2 x 10(exp 11). This result has fundamental implications for quantum gravity models. I will also discuss the possibilities of using more sensitive space based detection techniques to improve searches for LIV in the future.

  19. The Spitzer/Swift Gamma-Ray Burst Host Galaxy Legacy Survey

    NASA Astrophysics Data System (ADS)

    Perley, Daniel; Berger, Edo; Butler, Nathaniel; Cenko, S. Bradley; Chary, Ranga-Ram; Cucchiara, Antonino; Ellis, Richard; Fong, Wen-fai; Fruchter, Andrew; Fynbo, Johan; Gehrels, Neil; Graham, John; Greiner, Jochen; Hjorth, Jens; Hunt, Leslie; Jakobsson, Pall; Kruehler, Thomas; Laskar, Tanmoy; Le Floc'h, Emerich; Levan, Andrew; Levesque, Emily; Littlejohns, Owen; Malesani, Daniele; Michalowski, Michal; Milvang-Jensen, Bo; Prochaska, J. Xavier; Salvaterra, Ruben; Schulze, Steve; Schady, Patricia; Tanvir, Nial; de Ugarte Postigo, Antonio; Vergani, Susanna; Watson, Darach

    2016-08-01

    Long-duration gamma-ray bursts act as beacons to the sites of star-formation in the distant universe. GRBs reveal galaxies too faint and star-forming regions too dusty to characterize in detail using any other method, and provide a powerful independent constraint on the evolution of the cosmic star-formation rate density at high-redshift. However, a full understanding of the GRB phenomenon and its relation to cosmic star-formation requires connecting the observations obtained from GRBs to the properties of the galaxies hosting them. The large majority of GRBs originate at moderate to high redshift (z>1) and Spitzer has proven crucial for understanding the host population, given its unique ability to observe the rest-frame NIR and its unrivaled sensitivity and efficiency. We propose to complete a comprehensive public legacy survey of the Swift GRB host population to build on our earlier successes and push beyond the statistical limits of previous, smaller efforts. Our survey will enable a diverse range of GRB and galaxy science including: (1) to quantitatively and robustly map the connection between GRBs and cosmic star-formation to constrain the GRB progenitor and calibrate GRB rate-based measurements of the high-z cosmic star-formation rate; (2) to constrain the luminosity function of star-forming galaxies at the faint end and at high redshift; (3) to understand how the ISM properties seen in absorption in high-redshift galaxies unveiled by GRBs - metallicity, dust column, dust properties - connect to global properties of the host galaxies such as mass and age. Building on a decade of experience at both observatories, our observations will create an enduring joint Swift-Spitzer legacy sample - providing the definitive resource with which to examine all aspects of the GRB/galaxy connection for years to come and setting the stage for intensive JWST follow-up of the most interesting sources from our sample.

  20. Classification and Energetics of Cosmological Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Shahmoradi, Amir; Nemiroff, R. J.

    2014-01-01

    We present a quantitative phenomenological classification method for cosmological Gamma-Ray Bursts (GRBs) into two known subgroups of Short & Long GRBs based on the prompt gamma-ray emission properties. The classification is intended to be universal, independently of the gamma-ray detector specifications and can be used to classify a given GRB based on its observer- or rest-frame prompt variables. We show that the joint population distribution of the four main prompt emission parameters in both classes of GRBs: the isotropic luminosity (Liso), the isotropic total emission (Eiso), the rest-frame spectral peak energy (Epz) and the rest-frame duration of the prompt emission (T90z), and the interrelations among them can be well represented by a multivariate log-normal distribution, once corrected for the detector triggering threshold. The population properties of the two classes of Long & Short GRBs bear striking similarities in the 4-dimensional space of Liso, Eiso, Epz & T90z, possibly indicating a common origin and similar mechanisms responsible for the observed correlations among the prompt emission parameters.

  1. 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.

  2. A NEW CLASS OF GAMMA-RAY BURSTS FROM STELLAR DISRUPTIONS BY INTERMEDIATE-MASS BLACK HOLES

    SciTech Connect

    Gao, H.; Lu, Y.; Zhang, S. N.

    2010-07-01

    It has been argued that the long gamma-ray burst (GRB) of GRB 060614 without an associated supernova (SN) has challenged the current classification and fuel model for long GRBs, and thus a tidal disruption model has been proposed to account for such an event. Since it is difficult to detect SNe for long GRBs at high redshift, the absence of an SN association cannot be regarded as the solid criterion for a new classification of long GRBs similar to GRB 060614, called GRB 060614-type bursts. Fortunately, we now know that there is an obvious periodic substructure observed in the prompt light curve of GRB 060614. We thus use such periodic substructure as a potential criterion to categorize some long GRBs into a new class of bursts, which might have been fueled by an intermediate-mass black hole (IMBH) gulping a star, rather than a massive star collapsing to form a black hole. Therefore, the second criterion to recognize for this new class of bursts is whether they fit the tidal disruption model. From a total of 328 Swift GRBs with accurately measured durations and without SN association, we find 25 GRBs satisfying the criteria for GRB 060614-type bursts: seven of them are with known redshifts and 18 with unknown redshifts. These new bursts are {approx}6% of the total Swift GRBs, which are clustered into two subclasses: Type I and Type II with considerably different viscous parameters of accretion disks formed by tidally disrupting their different progenitor stars. We suggest that the two different kinds of progenitors are solar-type stars and white dwarfs: the progenitors for four Type I bursts with viscous parameter of around 0.1 are solar-type stars, and the progenitors for 21 Type II bursts with viscous parameter of around 0.3 are white dwarfs. The potential applications of this new class of GRBs as cosmic standard candles are discussed briefly.

  3. 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.

  4. 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.

  5. How Special Are Dark Gamma-Ray Burst: A Diagnostic Tool

    NASA Technical Reports Server (NTRS)

    Rod, Evert; Wiers, Ralph A. M. J.; Kouveliotou, Chryssa; Kaper, Lex; Kaneko, Yuki; Kaper, Lex

    2005-01-01

    We present here a comprehensive study of the optical/near-infrared (IR) upper limits for gamma-ray bursts that have an X-ray afterglow. We have extrapolated the X-ray afterglows to optical wavelengths based on the physics of the fireball blast wave model and compared these results with optical upper limits for a large sample of bursts. We find a small set of only three bursts out of a sample of 20 for which the upper limits are not compatible with their X-ray afterglow properties within the context of any blast wave model. This sparse sample does not allow us to conclusively determine the cause of this optical/near-IR deficit. Extinction in the host galaxy is a likely cause, but high redshifts and different afterglow mechanisms might also explain the deficit in some cases. We note that the three bursts appear to have higher than average gamma-my peak fluxes. In a magnitude versus time diagram the bursts are separated from the majority of bursts with a detected optical/near-IR afterglow. However, two gamma- ray bursts with an optical afterglow (one of which is highly reddened) also fall in this region with dark bursts, making it likely that dark bursts are at the faint end of the set of optically detected bursts, and therefore the dark bursts likely form a continuum with the bursts with a detected optical afterglow. Our work provides a useful diagnostic tool for follow-up observations for potentially dark bursts; applied to the events detected with the Swift satellite, it will significantly increase our sample of truly dark bursts and shed light upon their nature. Subject headings: dust, extinction - gamma rays: bursts Online material: machine-readable tables

  6. 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.

  7. 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.

  8. Cosmological Parameters from Supernovae Associated with Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Li, Xue; Hjorth, Jens; Wojtak, Radosław

    2014-11-01

    We report estimates of the cosmological parameters Ω m and ΩΛ 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 _m, Ω Λ ) = (0.58+0.22-0.25,0.42 +0.25-0.22). 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.

  9. Distinguishing short and long Fermi gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Tarnopolski, M.

    2015-11-01

    Two classes of gamma-ray bursts (GRBs), short and long, have been determined without any doubts, and are usually ascribed to different progenitors, yet these classes overlap for a variety of descriptive parameters. A subsample of 46 long and 22 short Fermi GRBs with estimated Hurst Exponents (HEs), complemented by minimum variability time-scales (MVTS) and durations (T90) is used to perform a supervised machine learning and Monte Carlo simulation using a support vector machine algorithm. It is found that while T90 itself performs very well in distinguishing short and long GRBs, the overall success ratio is higher when the training set is complemented by MVTS and HE. These results may allow us to introduce a new (non-linear) parameter that might provide less ambiguous classification of GRBs.

  10. Effect of Dust Extinction on Gamma-ray Burst Afterglows

    NASA Astrophysics Data System (ADS)

    Lŭ, Gu-Jing; Shao, Lang; Jin, Zhi-Ping; Wei, Da-Ming

    2011-10-01

    In order to study the effect of dust extinction on the afterglow of gamma-ray bursts (GRBs), we carry out numerical calculations with high precision based on the rigorous Mie theory and the latest optical properties of interstellar dust grains, and analyze the different extinction curves produced by dust grains with different physical parameters. Our results indicate that the absolute extinction quantity is substantially determined by the medium density and metallicity. However, the shape of the extinction curve is mainly determined by the size distribution of the dust grains. If the dust grains aggregate to form larger ones, they will cause a flatter or grayer extinction curve with lower extinction quantity. On the contrary, if the dust grains are disassociated to smaller ones due to some uncertain processes, they will cause a steeper extinction curve with larger amount of extinction. These results might provide an important insight into understanding the origin of the optically dark GRBs.

  11. 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

  12. 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''.

  13. Short Gamma-ray Bursts: Observations and Physics

    NASA Astrophysics Data System (ADS)

    Janka, H.-Thomas

    2007-04-01

    The aim of the workshop, which will be held at the scenic Ringberg castle, is supposed to bring together astrophysicists, physicists, and astronomers from different fields in order to discuss recent observational and theoretical discoveries and developments on short gamma-ray bursts. In particular, we plan to address the following topics: * recent short GRB observations * environments and host galaxies of short GRBs * is there a 3rd class of GRBs? * modeling GRB engines and jet outflows * rate and redshift predictions for short GRBs * the fireball model and short GRBs * gravitational-wave signals from short GRBs * neutrino signals from short GRBs * microphysics needed for modeling short GRBs and their engines Scientific and Local organizing committee members: H.-Thomas Janka (Max Planck Institute for Astrophysics, Garching), Miguel Aloy (University of Valencia), Jochen Greiner (Max Planck Institute for Extraterrestrial Physics), Sandra Savaglio (Max Planck Institute for Extraterrestrial Physics), Shri Kulkarni (California Institute of Technology, Pasadena)

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

    NASA Astrophysics Data System (ADS)

    Watson, D.

    2014-07-01

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

  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. GAMMA-RAY BURST FLARES: ULTRAVIOLET/OPTICAL FLARING. I

    SciTech Connect

    Swenson, C. A.; Roming, P. W. A.; De Pasquale, M.; Oates, S. R.

    2013-09-01

    We present a previously unused method for the detection of flares in gamma-ray burst (GRB) light curves and use this method to detect flares in the ultraviolet/optical. The algorithm makes use of the Bayesian Information Criterion to analyze the residuals of the fitted light curve, removing all major features, and to determine the statistically best fit to the data by iteratively adding additional ''breaks'' to the light curve. These additional breaks represent the individual components of the detected flares: T{sub start}, T{sub stop}, and T{sub peak}. We present the detection of 119 unique flaring periods detected by applying this algorithm to light curves taken from the Second Swift Ultraviolet/Optical Telescope (UVOT) GRB Afterglow Catalog. We analyzed 201 UVOT GRB light curves and found episodes of flaring in 68 of the light curves. For those light curves with flares, we find an average number of {approx}2 flares per GRB. Flaring is generally restricted to the first 1000 s of the afterglow, but can be observed and detected beyond 10{sup 5} s. More than 80% of the flares detected are short in duration with {Delta}t/t of <0.5. Flares were observed with flux ratios relative to the underlying light curve of between 0.04 and 55.42. Many of the strongest flares were also seen at greater than 1000 s after the burst.

  17. How Soft Gamma Repeaters Might Make Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Katz, J. I.

    2016-08-01

    There are several phenomenological similarities between soft gamma repeaters (SGRs) and fast radio bursts (FRBs), including duty factors, timescales, and repetition. The sudden release of magnetic energy in a neutron star magnetosphere, as in popular models of SGRs, can meet the energy requirements of FRBs, but requires both the presence of magnetospheric plasma, in order for dissipation to occur in a transparent region, and a mechanism for releasing much of that energy quickly. FRB sources and SGRs are distinguished by long-lived (up to thousands of years) current-carrying coronal arches remaining from the formation of the young neutron star, and their decay ends the phase of SGR/AXP/FRB activity even though “magnetar” fields may persist. Runaway increases in resistance when the current density exceeds a threshold, releases magnetostatic energy in a sudden burst, and produces high brightness GHz emission of FRB by a coherent process. SGRs are produced when released energy thermalizes as an equlibrium pair plasma. The failures of some alternative FRB models and the non-detection of SGR 1806-20 at radio frequencies are discussed in the appendices.

  18. 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.

  19. Gamma-Ray Burst Flares: Ultraviolet/Optical Flaring. I.

    NASA Astrophysics Data System (ADS)

    Swenson, C. A.; Roming, P. W. A.; De Pasquale, M.; Oates, S. R.

    2013-09-01

    We present a previously unused method for the detection of flares in gamma-ray burst (GRB) light curves and use this method to detect flares in the ultraviolet/optical. The algorithm makes use of the Bayesian Information Criterion to analyze the residuals of the fitted light curve, removing all major features, and to determine the statistically best fit to the data by iteratively adding additional "breaks" to the light curve. These additional breaks represent the individual components of the detected flares: T start, T stop, and T peak. We present the detection of 119 unique flaring periods detected by applying this algorithm to light curves taken from the Second Swift Ultraviolet/Optical Telescope (UVOT) GRB Afterglow Catalog. We analyzed 201 UVOT GRB light curves and found episodes of flaring in 68 of the light curves. For those light curves with flares, we find an average number of ~2 flares per GRB. Flaring is generally restricted to the first 1000 s of the afterglow, but can be observed and detected beyond 105 s. More than 80% of the flares detected are short in duration with Δt/t of <0.5. Flares were observed with flux ratios relative to the underlying light curve of between 0.04 and 55.42. Many of the strongest flares were also seen at greater than 1000 s after the burst.

  20. Radio afterglows and host galaxies of gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Li, Long-Biao; Zhang, Zhi-Bin; Huang, Yong-Feng; Wu, Xue-Feng; Kong, Si-Wei; Li, Di; Chang, Heon-Young; Choi, Chul-Sung

    2015-08-01

    Considering the contribution of emission from the host galaxies of gamma-ray bursts (GRBs) to radio afterglows, we investigate the effect of host galaxies on observations statistically. For the three types of event, i.e. low-luminosity, standard and high-luminosity GRBs, it is found that a tight correlation exists between the ratio of the radio flux (RRF) of the host galaxy to the total radio peak emission and the observational frequency. Towards lower frequencies, in particular, the contribution from the host increases significantly. The correlation can be used to obtain a useful estimate for the radio brightness of those host galaxies that only have very limited radio afterglow data. Using this prediction, we reconsidered the theoretical radio afterglow light curves for four kinds of event: high-luminosity, low-luminosity, standard and failed GRBs, taking into account the contribution from host galaxies and aiming to explore the detectability of these events by the Five-hundred-metre Aperture Spherical radio Telescope (FAST). Lying at a typical redshift of z = 1, most of the events can be detected easily by FAST. For the less fierce low-luminosity GRBs, their radio afterglows are not strong enough to exceed the sensitivity limit of FAST at such distances. However, since a large number of low-luminosity bursts actually happen very near to us, it is expected that FAST will still be able to detect many of them.

  1. Radio Constraints on Heavily Obscured Star Formation within Dark Gamma-Ray Burst Host Galaxies

    NASA Astrophysics Data System (ADS)

    Perley, D. A.; Perley, R. A.

    2013-12-01

    Highly dust-obscured starbursting galaxies (submillimeter galaxies and their ilk) represent the most extreme sites of star formation in the distant universe and contribute significantly to overall cosmic star formation beyond z > 1.5. Some stars formed in these environments may also explode as gamma-ray bursts (GRBs) and contribute to the population of "dark" bursts. Here we present Very Large Array wideband radio-continuum observations of 15 heavily dust-obscured Swift GRBs to search for radio synchrotron emission associated with intense star formation in their host galaxies. Most of these targets (11) are not detected. Of the remaining four objects, one detection is marginal, and for two others we cannot yet rule out the contribution of a long-lived radio afterglow. The final detection is secure, but indicates a star formation rate (SFR) roughly consistent with the dust-corrected UV-inferred value. Most galaxies hosting obscured GRBs are therefore not forming stars at extreme rates, and the amount of optical extinction seen along a GRB afterglow sightline does not clearly correlate with the likelihood that the host has a sufficiently high SFR to be radio-detectable. While some submillimeter galaxies do readily produce GRBs, these GRBs are often not heavily obscured—suggesting that the outer (modestly obscured) parts of these galaxies overproduce GRBs and the inner (heavily obscured) parts underproduce GRBs relative to their respective contributions to star formation, hinting at strong chemical or initial mass function gradients within these systems.

  2. Short Gamma-Ray Bursts from the Merger of Two Black Holes

    NASA Astrophysics Data System (ADS)

    Perna, Rosalba; Lazzati, Davide; Giacomazzo, Bruno

    2016-04-01

    Short gamma-ray bursts (GRBs) are explosions of cosmic origins believed to be associated with the merger of two compact objects, either two neutron stars or a neutron star and a black hole (BH). The presence of at least one neutron star has long been thought to be an essential element of the model: its tidal disruption provides the needed baryonic material whose rapid accretion onto the post-merger BH powers the burst. The recent tentative detection by the Fermi satellite of a short GRB in association with the gravitational wave signal GW150914 produced by the merger of two BHs has challenged this standard paradigm. Here, we show that the evolution of two high-mass, low-metallicity stars with main-sequence rotational speeds a few tens of percent of the critical speed eventually undergoing a weak supernova explosion can produce a short GRB. The outer layers of the envelope of the last exploding star remain bound and circularize at large radii. With time, the disk cools and becomes neutral, suppressing the magnetorotational instability, and hence the viscosity. The disk remains “long-lived dead” until tidal torques and shocks during the pre-merger phase heat it up and re-ignite accretion, rapidly consuming the disk and powering the short GRB.

  3. Radio constraints on heavily obscured star formation within dark gamma-ray burst host galaxies

    SciTech Connect

    Perley, D. A.; Perley, R. A.

    2013-12-01

    Highly dust-obscured starbursting galaxies (submillimeter galaxies and their ilk) represent the most extreme sites of star formation in the distant universe and contribute significantly to overall cosmic star formation beyond z > 1.5. Some stars formed in these environments may also explode as gamma-ray bursts (GRBs) and contribute to the population of 'dark' bursts. Here we present Very Large Array wideband radio-continuum observations of 15 heavily dust-obscured Swift GRBs to search for radio synchrotron emission associated with intense star formation in their host galaxies. Most of these targets (11) are not detected. Of the remaining four objects, one detection is marginal, and for two others we cannot yet rule out the contribution of a long-lived radio afterglow. The final detection is secure, but indicates a star formation rate (SFR) roughly consistent with the dust-corrected UV-inferred value. Most galaxies hosting obscured GRBs are therefore not forming stars at extreme rates, and the amount of optical extinction seen along a GRB afterglow sightline does not clearly correlate with the likelihood that the host has a sufficiently high SFR to be radio-detectable. While some submillimeter galaxies do readily produce GRBs, these GRBs are often not heavily obscured—suggesting that the outer (modestly obscured) parts of these galaxies overproduce GRBs and the inner (heavily obscured) parts underproduce GRBs relative to their respective contributions to star formation, hinting at strong chemical or initial mass function gradients within these systems.

  4. 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.

  5. The progenitors of extended emission gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Gompertz, B. P.

    2015-06-01

    Gamma-ray bursts (GRBs) are the most luminous transient events in the Universe, and as such are associated with some of the most extreme processes in nature. They come in two types: long and short, nominally separated either side of a two second divide in gamma-ray emission duration. The short class (those with durations of less than two seconds) are believed to be due to the merger of two compact objects, most likely neutron stars. Within this population, a small subsection exhibit an apparent extra high-energy emission feature, which rises to prominence several seconds after the initial emission event. These are the extended emission (EE) bursts. This thesis investigates the progenitors of the EE sample, including what drives them, and where they fit in the broader context of short GRBs. The science chapters outline a rigorous test of the magnetar model, in which the compact object merger results in a massive, rapidly-rotating neutron star with an extremely strong magnetic field. The motivation for this central engine is the late-time plateaux seen in some short and EE GRBs, which can be interpreted as energy injection from a long-lived central engine, in this case from the magnetar as it loses angular momentum along open field lines. Chapter 2 addresses the energy budget of such a system, including whether the EE component is consistent with the rotational energy reservoir of a millisecond neutron star, and the implications the model has for the physical properties of the underlying magnetar. Chapter 3 proposes a potential mechanism by which EE may arise, and how both classes may be born within the framework of a single central engine. Chapter 4 addresses the broadband signature of both short and EE GRBs, and provides some observational tests that can be used to either support or contradict the model.

  6. COSMOLOGICAL IMPLICATIONS OF FAST RADIO BURST/GAMMA-RAY BURST ASSOCIATIONS

    SciTech Connect

    Deng, Wei; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2014-03-10

    If a small fraction of fast radio bursts (FRBs) are associated with gamma-ray bursts (GRBs), as recently suggested by Zhang, the combination of redshift measurements of GRBs and dispersion measure (DM) measurements of FRBs opens a new window to study cosmology. At z < 2 where the universe is essentially fully ionized, detections of FRB/GRB pairs can give an independent measurement of the intergalactic medium portion of the baryon mass fraction, Ω {sub b} f {sub IGM}, of the universe. If a good sample of FRB/GRB associations are discovered at higher redshifts, the free electron column density history can be mapped, which can be used to probe the reionization history of both hydrogen and helium in the universe. We apply our formulation to GRBs 101011A and 100704A that each might have an associated FRB, and constrained Ω {sub b} f {sub IGM} to be consistent with the value derived from other methods. The methodology developed here is also applicable, if the redshifts of FRBs not associated with GRBs can be measured by other means.

  7. The Fermi GBM gamma-ray burst time-resolved spectral catalog: brightest bursts in the first four years

    NASA Astrophysics Data System (ADS)

    Yu, Hoi-Fung; Preece, Robert D.; Greiner, Jochen; Narayana Bhat, P.; Bissaldi, Elisabetta; Briggs, Michael S.; Cleveland, William H.; Connaughton, Valerie; Goldstein, Adam; von Kienlin, Andreas; Kouveliotou, Chryssa; Mailyan, Bagrat; Meegan, Charles A.; Paciesas, William S.; Rau, Arne; Roberts, Oliver J.; Veres, Péter; Wilson-Hodge, Colleen; Zhang, Bin-Bin; van Eerten, Hendrik J.

    2016-04-01

    Aims: We aim to obtain high-quality time-resolved spectral fits of gamma-ray bursts observed by the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Methods: We performed time-resolved spectral analysis with high temporal and spectral resolution of the brightest bursts observed by Fermi GBM in its first four years of mission. Results: We present the complete catalog containing 1491 spectra from 81 bursts with high spectral and temporal resolution. Distributions of parameters, statistics of the parameter populations, parameter-parameter and parameter-uncertainty correlations, and their exact values are obtained and presented as main results in this catalog. We report a criterion that is robust enough to automatically distinguish between different spectral evolutionary trends between bursts. We also search for plausible blackbody emission components and find that only three bursts (36 spectra in total) show evidence of a pure Planck function. It is observed that peak energy and the averaged, time-resolved power-law index at low energy are slightly harder than the time-integrated values. Time-resolved spectroscopic results should be used instead of time-integrated results when interpreting physics from the observed spectra. Tables A.1 and B.1 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/588/A135

  8. Searches for cosmic-string gravitational-wave bursts in Mock LISA Data

    NASA Astrophysics Data System (ADS)

    Cohen, Michael I.; Cutler, Curt; Vallisneri, Michele

    2010-09-01

    A network of observable, macroscopic cosmic (super-)strings may well have formed in the early Universe. If so, the cusps that generically develop on cosmic-string loops emit bursts of gravitational radiation that could be detectable by gravitational-wave interferometers, such as the ground-based LIGO/Virgo detectors and the planned, space-based LISA detector. Here we report on two versions of a LISA-oriented string-burst search pipeline that we have developed and tested within the context of the Mock LISA Data Challenges. The two versions rely on the publicly available MultiNest and PyMC software packages, respectively. To reduce the effective dimensionality of the search space, our implementations use the F-statistic to analytically maximize over the signal's amplitude and polarization, \\mathcal {A} and ψ, and use the FFT to search quickly over burst arrival times tC. The standard F-statistic is essentially a frequentist statistic that maximizes the likelihood; we also demonstrate an approximate, Bayesian version of the F-statistic that incorporates realistic priors on \\mathcal {A} and ψ. We calculate how accurately LISA can expect to measure the physical parameters of string-burst sources, and compare to results based on the Fisher-matrix approximation. To understand LISA's angular resolution for string-burst sources, we draw maps of the waveform fitting factor (maximized over (\\mathcal {A}, \\psi, t_C)) as a function of the sky position; these maps dramatically illustrate why (for LISA) inferring the correct sky location of the emitting string loop will often be practically impossible. In addition, we identify and elucidate several symmetries that are imbedded in this search problem, and we derive the distribution of cut-off frequencies fmax for observable bursts.

  9. High Energy Cosmic Electrons: Messengers from Nearby Cosmic Ray Sources or Dark Matter?

    NASA Technical Reports Server (NTRS)

    Moiseev, Alexander

    2011-01-01

    This slide presentation reviews the recent discoveries by the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Telescope in reference to high energy cosmic electrons, and whether their source is cosmic rays or dark matter. Specific interest is devoted to Cosmic Ray electrons anisotropy,

  10. 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.

  11. CONSTRAINING THE EMISSIVITY OF ULTRAHIGH ENERGY COSMIC RAYS IN THE DISTANT UNIVERSE WITH THE DIFFUSE GAMMA-RAY EMISSION

    SciTech Connect

    Wang Xiangyu; Liu Ruoyu; Aharonian, Felix

    2011-08-01

    Ultrahigh cosmic rays (UHECRs) with energies {approx}> 10{sup 19} eV emitted at cosmological distances will be attenuated by cosmic microwave and infrared background radiation through photohadronic processes. Lower energy extragalactic cosmic rays ({approx}10{sup 18}-10{sup 19} eV) can only travel a linear distance smaller than {approx}Gpc in a Hubble time due to the diffusion if the extragalactic magnetic fields are as strong as nano-Gauss. These prevent us from directly observing most of the UHECRs in the universe, and thus the observed UHECR intensity reflects only the emissivity in the nearby universe within hundreds of Mpc. However, UHECRs in the distant universe, through interactions with the cosmic background photons, produce UHE electrons and gamma rays that in turn initiate electromagnetic cascades on cosmic background photons. This secondary cascade radiation forms part of the extragalactic diffuse GeV-TeV gamma-ray radiation and, unlike the original UHECRs, is observable. Motivated by new measurements of extragalactic diffuse gamma-ray background radiation by Fermi/Large Area Telescope, we obtained upper limit placed on the UHECR emissivity in the distant universe by requiring that the cascade radiation they produce not exceed the observed levels. By comparison with the gamma-ray emissivity of candidate UHECR sources (such as gamma-ray bursts (GRBs) and active galactic nuclei) at high redshifts, we find that the obtained upper limit for a flat proton spectrum is {approx_equal} 10{sup 1.5} times larger than the gamma-ray emissivity in GRBs and {approx_equal} 10 times smaller than the gamma-ray emissivity in BL Lac objects. In the case of iron nuclei composition, the derived upper limit of UHECR emissivity is a factor of 3-5 times higher. Robust upper limit on the cosmogenic neutrino flux is further obtained, which is marginally reachable by the Icecube detector and the next-generation detector JEM-EUSO.

  12. A search for fast radio bursts associated with gamma-ray bursts

    SciTech Connect

    Palaniswamy, Divya; Wayth, Randall B.; Trott, Cathryn M.; Tingay, Steven J.; Reynolds, Cormac; McCallum, Jamie N.

    2014-07-20

    The detection of seven fast radio bursts (FRBs) has recently been reported. FRBs are short duration (∼1 ms), highly dispersed radio pulses from astronomical sources. The physical interpretation for the FRBs remains unclear but is thought to involve highly compact objects at cosmological distance. It has been suggested that a fraction of FRBs could be physically associated with gamma-ray bursts (GRBs). Recent radio observations of GRBs have reported the detection of two highly dispersed short duration radio pulses using a 12 m radio telescope at 1.4 GHz. Motivated by this result, we have performed a systematic and sensitive search for FRBs associated with GRBs. We have observed five GRBs at 2.3 GHz using a 26 m radio telescope located at the Mount Pleasant Radio Observatory, Hobart. The radio telescope was automated to rapidly respond to Gamma-ray Coordination Network notifications from the Swift satellite and slew to the GRB position within ∼140 s. The data were searched for pulses up to 5000 pc cm{sup –3} in dispersion measure and pulse widths ranging from 640 μs to 25.60 ms. We did not detect any events ≥6σ. An in depth statistical analysis of our data shows that events detected above 5σ are consistent with thermal noise fluctuations only. A joint analysis of our data with previous experiments shows that previously claimed detections of FRBs from GRBs are unlikely to be astrophysical. Our results are in line with the lack of consistency noted between the recently presented FRB event rates and GRB event rates.

  13. Is the Metallicity of the Progenitor of Long Gamma-Ray Bursts Really Low?

    NASA Astrophysics Data System (ADS)

    Hao, Jing-Meng; Yuan, Ye-Fei

    2013-07-01

    Observations of long gamma-ray bursts (LGRBs) offer a unique opportunity to probe the history of cosmic star formation, although whether LGRBs are biased tracers remains highly debated. Based on an extensive sample of LGRBs compiled by Robertson & Ellis, we analyze various models of star formation rate, combining the possible effect of the cosmic metallicity evolution under the assumption that LGRBs preferentially occur in low-metallicity galaxies. The models of star formation rate tested in this work include empirical fits from observational data as well as a self-consistent model calculated from the hierarchical structure formation scenario. Comparing with the observational data, we find a relatively higher metallicity cut of Z >~ 0.6 Z ⊙ for the empirical fits and no metallicity cut for the self-consistent model. These results imply that there is no strong bias toward low metallicity in LGRB host galaxies, in contrast to previous studies suggesting a cut of Z ~ 0.1-0.3 Z ⊙, and that the inferred low-metallicity dependencies of LGRBs are strongly related to the specific models of star formation rate. Furthermore, a significant fraction of LGRBs that occur in small halos down to 3 × 108 M ⊙ can provide an alternative explanation for the difference between the star formation rate and the LGRB rate.

  14. Toward cosmological-model-independent calibrations for the luminosity relations of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Ding, Xuheng; Li, Zhengxiang; Zhu, Zong-Hong

    2015-05-01

    Gamma-ray bursts (GRBs), have been widely used as distance indicators to measure the cosmic expansion and explore the nature of dark energy. A popular method adopted in previous works is to calibrate the luminosity relations which are responsible for distance estimation of GRBs with more primary (low redshift) cosmic distance ladder objects, type Ia supernovae (SNe Ia). Since distances of SNe Ia in all SN Ia samples used to calibrate GRB luminosity relations were usually derived from the global fit in a specific cosmological model, the distance of GRB at a given redshift calibrated with matching SNe Ia was still cosmological-model-dependent. In this paper, we first directly determine the distances of SNe Ia with the Angular Diameter Distances (ADDs) of galaxy clusters without any assumption for the background of the universe, and then calibrate GRB luminosity relations with our cosmology-independent distances of SNe Ia. The results suggest that, compared to the previous original manner where distances of SNe Ia used as calibrators are determined from the global fit in a particular cosmological model, our treatments proposed here yield almost the same calibrations of GRB luminosity relations and the cosmological implications of them do not suffer any circularity.

  15. IS THE METALLICITY OF THE PROGENITOR OF LONG GAMMA-RAY BURSTS REALLY LOW?

    SciTech Connect

    Hao Jingmeng; Yuan Yefei

    2013-07-20

    Observations of long gamma-ray bursts (LGRBs) offer a unique opportunity to probe the history of cosmic star formation, although whether LGRBs are biased tracers remains highly debated. Based on an extensive sample of LGRBs compiled by Robertson and Ellis, we analyze various models of star formation rate, combining the possible effect of the cosmic metallicity evolution under the assumption that LGRBs preferentially occur in low-metallicity galaxies. The models of star formation rate tested in this work include empirical fits from observational data as well as a self-consistent model calculated from the hierarchical structure formation scenario. Comparing with the observational data, we find a relatively higher metallicity cut of Z {approx}> 0.6 Z{sub Sun} for the empirical fits and no metallicity cut for the self-consistent model. These results imply that there is no strong bias toward low metallicity in LGRB host galaxies, in contrast to previous studies suggesting a cut of Z {approx} 0.1-0.3 Z{sub Sun }, and that the inferred low-metallicity dependencies of LGRBs are strongly related to the specific models of star formation rate. Furthermore, a significant fraction of LGRBs that occur in small halos down to 3 Multiplication-Sign 10{sup 8} M{sub Sun} can provide an alternative explanation for the difference between the star formation rate and the LGRB rate.

  16. 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.

  17. Spectral Properties of Relativistic Shocks in Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Papathanassiou, Hariklia

    1998-12-01

    The origin of Gamma Ray Bursts (GRB) is still embedded in mystery. There is, however, good evidence that, irrespective of the trigger mechanism and the progenitor's identity, GRBs involve ultra-relativistic flows. It has been suggested that such outflows develop shocks due to their deceleration by the surrounding medium (external shocks) and, possibly, due to variability within the flow (internal shocks). Such shocks are believed to act as particle accelerators and magnetic field amplifiers. In this thesis, we study the spectral properties of external and internal shocks. We employ an extensive parameterization of the uncertain physical processes (electron injection and acceleration, magnetic field amplification) in the shocks and calculate the time averaged spectra that result from synchrotron emission and its inverse Compton scattered counterpart. Overall, the resulting spectra share the defining properties of the observed ones: they are non-thermal, they show a break (whose value is not fixed by the model), and spectral slopes in the range that was revealed by fitting BATSE spectra. The hardness-duration anti-correlation and the brightness-hardness correlation are properties inherent to the model spectra (both in external and internal shocks). The spectra are, in general, very broad and counterparts in higher and lower frequencies are predicted. Behaviors such as X-ray deficiency and occasional X-ray excess are common. We discuss the broad-band properties of the spectra and the spectral differences between internal and external shocks bursts. We also examine the spectral properties arising from the deceleration of an unsteady wind that results in hard and delayed emission from external shocks following the main burst from internal ones. We conduct a parameter search in order to identify the environments external shock bursts take place in, as well as the radiative properties of the shocks. Internal shocks are semi-relativistic (v≃0.6c), but one of the external

  18. Detection of signature consistent with cosmological time dilation in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    If gamma ray bursts are at cosmological distances-as suggested by their isotropic distribution on the sky and by their number-intensity relation-then the burst profiles will be stretched in time, by an amount proportional to the redshift, 1 + Z. We have tested data from the Compton Gamma Ray Observatory's (CGRO's) Burst and Transient Source Experiment (BATSE) for such time dilation. Out of 590 bursts observed by BATSE, 131 bursts were analyzed; bursts with durations shorter than 1.5 s were excluded. We used three tests to compare the timescales of bright and dim bursts, the latter, on average, being more distant than the former. Our measures of timescale are constructed to avoid selection effects arising from intensity differences by rescaling all bursts to fiducial levels of peak intensity and noise bias. (1) We found that the total rescaled count above background for the dim burst ensemble is approximately twice that for the brightest bursts-translating into longer durations for the dim bursts. (2) Wavelet-transform decompositions of the burst profiles confirmed that this dilation operates over a broad range of timescales. (3) Structure on the shortest timescales was examined using a procedure which aligns the highest peaks of profiles from which the noise has been optimally removed using a wavelet threshold technique. In all three tests, the dim bursts are stretched by a factor of approximately 2 relative to the bright ones, over seven octaves of timescale. We calibrated the measurements by dilating synthetic bursts that approximate the temporal characteristics of bright BATSE bursts. Results are consistent with bursts at BATSE's peak-flux completeness limit being at cosmological distances corresponding to Z approximately equal to 1, and thus with independent cosmological interpretations of the BATSE number-intensity relation. Alternative explanations of our results, arising from the nature of physical processes in bursts, are still possible.

  19. THE SECOND SWIFT BURST ALERT TELESCOPE GAMMA-RAY BURST CATALOG

    SciTech Connect

    Sakamoto, T.; Baumgartner, W. H.; Cummings, J. R.; Krimm, H. A.; Barthelmy, S. D.; Gehrels, N.; Markwardt, C. B.; Parsons, A. M.; Tueller, J.; Fenimore, E. E.; Palmer, D. M.; Sato, G.; Stamatikos, M.; Ukwatta, T. N.; Zhang, B.

    2011-07-01

    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 parameters 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 T{sub 90} and T{sub 50} 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 {sup obs}{sub 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 only 10% of the BAT observed photon indices are outside the allowed region of the synchrotron shock model. We see no obvious observed trend in the BAT T{sub 90} and the observed spectra

  20. Swift and Fermi Observations of the Early Afterglow of the Short Gamma-Ray Burst 090510

    NASA Astrophysics Data System (ADS)

    De Pasquale, M.; Schady, P.; Kuin, N. P. M.; Page, M. J.; Curran, P. A.; Zane, S.; Oates, S. R.; Holland, S. T.; Breeveld, A. A.; Hoversten, E. A.; Chincarini, G.; Grupe, D.; Abdo, A. A.; Ackermann, M.; Ajello, M.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Burnett, T. H.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Chekhtman, A.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Dermer, C. D.; de Angelis, A.; de Palma, F.; Dingus, B. L.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Fishman, G.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Granot, J.; Greiner, J.; Grenier, I. A.; Grove, J. E.; Guillemot, L.; Guiriec, S.; Harding, A. K.; Hayashida, M.; Hays, E.; Horan, D.; Hughes, R. E.; Jackson, M. S.; Jóhannesson, G.; Johnson, A. S.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kerr, M.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; McGlynn, S.; Meegan, C.; Mészáros, P.; Meurer, C.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Porter, T. A.; Preece, R.; Rainò, S.; Rando, R.; Razzano, M.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Rochester, L. S.; Rodriguez, A. Y.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sander, A.; Saz Parkinson, P. M.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Starck, J.-L.; Stecker, F. W.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Toma, K.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; van der Horst, A. J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; von Kienlin, A.; Waite, A. P.; Wang, P.; Winer, B. L.; Wood, K. S.; Wu, X. F.; Yamazaki, R.; Ylinen, T.; Ziegler, M.

    2010-02-01

    We present the observations of GRB090510 performed by the Fermi Gamma-Ray Space Telescope and the Swift observatory. This is a bright, short burst that shows an extended emission detected in the GeV range. 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. We discuss internal and external shock models for the broadband energy emission of this object.

  1. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  3. 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.

  4. 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.

  5. 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.

  6. Uncovering the intrinsic variability of gamma-ray bursts

    SciTech Connect

    Golkhou, Vahid Z.; Butler, Nathaniel R. E-mail: natbutler@asu.edu

    2014-05-20

    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 Δt {sub min} = 0.5 s, with the shortest timescale found being on the order of 10 ms. This short timescale suggests a compact central engine (3 × 10{sup 3} 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.

  7. Gamma-Ray Bursts: Afterglows and Central Engines

    NASA Astrophysics Data System (ADS)

    Cheng, K. S.; Lu, T.

    2001-01-01

    Gamma-ray bursts (GRBs) are the most intense transient gamma-ray events in the sky; this, together with the strong evidence (the isotropic and inhomogeneous distribution of GRBs detected by BASTE) that they are located at cosmological distances, makes them the most energetic events ever known. For example, the observed radiation energies of some GRBs are equivalent to the total convertion into radiation of the mass energy of more than one solar mass. This is thousand times stronger than the energy of a supernova explosion. Some unconventional energy mechanism and extremely high conversion efficiency for these mysterious events are required. The discovery of host galaxies and association with supernovae at cosmological distances by the recently launched satellite of BeppoSAX and ground based radio and optical telescopes in GRB afterglow provides further support to the cosmological origin of GRBs and put strong constraints on their central engine. It is the aim of this article to review the possible central engines, energy mechanisms, dynamical and spectral evolution of GRBs, especially focusing on the afterglows in multi-wavebands.

  8. 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.

  9. The Synergy of Gamma-Ray Burst Detectors In The Glast Era

    NASA Technical Reports Server (NTRS)

    Band, David L.

    2008-01-01

    Simultaneous observations by the large number of gamma-ray burst detectors operating in the GLAST era will provide the spectra, lightcurves and locations necessary for studying burst physics and testing the putative relations between intrinsic burst properties. The detectors' energy band and the accumulation timescale of their trigger system affect their sensitivity to hard vs. soft and long vs. short bursts. Coordination of the Swift and GLAST observing plans consistent with Swift's other science objectives could increase the rate of GLAST bursts with redshifts.

  10. Globin chain synthesis in single erythroid bursts from cord blood: studies on gamma leads to beta and G gamma leads to A gamma switches.

    PubMed

    Comi, P; Giglioni, B; Ottolenghi, S; Gianni, A M; Polli, E; Barba, P; Covelli, A; Migliaccio, G; Condorelli, M; Peschle, C

    1980-01-01

    Erythroid bursts from cord or adult blood were grown in methylcellulose cultures (3 international units of erythropoietin per plate). On day 13, single bursts were picked up and reincubated for 16-24 hr with [3H]leucine. Radioactive globin chains [alpha,beta,G gamma, and A gamma (Ala-136)] were analyzed by either isoelectric focusing on polyacrylamide gels and fluorography or carboxymethylcellulose chromatography. In all cases, alpha to non-alpha globin radioactivity ratios were close to 1. In single cord blood bursts, the values of both gamma-to-beta and G gamma-to-A gamma ratios were spread over a large spectrum and further characterized by a continuous rather than a bimodal distribution. Morever, the G gamma-to-A gamma ratios demonstrated in single bursts appeared to be directly correlated with the respective gamma-to-beta ratios. These data suggest that both the gamma leads to beta and the G gamma leads to A gamma switches are mediated via mechanisms modulating the relative activities of the different genes in the non-alpha globin gene cluster rather than via selection of clones committed to the preferential synthesis of beta and A gamma globins. In contrast with the results obtained with cord blood, individual adult blood bursts synthesize a lower and hence relatively more uniform amount of gamma globin chains. PMID:6153796

  11. Gravitino decay and the cosmic gamma-ray background

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1986-01-01

    It is argued that the cosmic gamma-ray background (CGB) spectrum does not exhibit evidence for the decay of light gravitinos, in contradiction to the suggestion by Olive and Silk (1985), who observed a bump near 1 MeV in the CGB radiation spectrum. It is suggested that better fits to the CGB spectrum would be provided by mechanisms generating a power-law spectrum which is flattened below about 2 MeV. Olive and Silk maintain that the decays of a long-lived particle such as the gravitino may be responsible for features in the gamma-ray spectrum near 1 MeV.

  12. Gamma-rays, cosmic rays, and galactic structure

    NASA Technical Reports Server (NTRS)

    Stecker, F. W.

    1976-01-01

    The relation of SAS-2 observations of galactic gamma-rays to the large scale distribution of cosmic rays and interstellar gas in the galaxy is reviewed. Starting with a discussion of production rates, the case for pion decay being the predominant production mechanism in the galactic disk above 100 MeV is reestablished, and it is also pointed out that Compton gamma-rays can be a significant source near l = 0. The concepts of four distinct galactic regions are defined, viz. the nebulodisk, ectodisk, radiodisk and exodisk. Bremsstrahlung and pion decay gamma-rays are associated with the first two (primarily the first) regions, and Compton gamma-rays and synchrotron radiation are associated with the latter two regions. On a large scale, the cosmic rays, interstellar gas (primarily H2 clouds in the inner galaxy) and gamma-ray emissivity all peak between 5 and 6 kpc from the galactic center. This correlation is related to correlation with other population I phenomena and is discussed in terms of the density wave concept of galactic structure.

  13. Sensory-evoked and spontaneous gamma and spindle bursts in neonatal rat motor cortex.

    PubMed

    An, Shuming; Kilb, Werner; Luhmann, Heiko J

    2014-08-13

    Self-generated neuronal activity originating from subcortical regions drives early spontaneous motor activity, which is a hallmark of the developing sensorimotor system. However, the neural activity patterns and role of primary motor cortex (M1) in these early movements are still unknown. Combining voltage-sensitive dye imaging (VSDI) with simultaneous extracellular multielectrode recordings in postnatal day 3 (P3)-P5 rat primary somatosensory cortex (S1) and M1 in vivo, we observed that tactile forepaw stimulation induced spindle bursts in S1 and gamma and spindle bursts in M1. Approximately 40% of the spontaneous gamma and spindle bursts in M1 were driven by early motor activity, whereas 23.7% of the M1 bursts triggered forepaw movements. Approximately 35% of the M1 bursts were uncorrelated to movements and these bursts had significantly fewer spikes and shorter burst duration. Focal electrical stimulation of layer V neurons in M1 mimicking physiologically relevant 40 Hz gamma or 10 Hz spindle burst activity reliably elicited forepaw movements. We conclude that M1 is already involved in somatosensory information processing during early development. M1 is mainly activated by tactile stimuli triggered by preceding spontaneous movements, which reach M1 via S1. Only a fraction of M1 activity transients trigger motor responses directly. We suggest that both spontaneously occurring and sensory-evoked gamma and spindle bursts in M1 contribute to the maturation of corticospinal and sensorimotor networks required for the refinement of sensorimotor coordination. PMID:25122889

  14. Search for simultaneous optical counterparts of gamma-ray bursts

    SciTech Connect

    Park, H S; Porrata, R A; Bionta, R M; Williams, G G

    2000-09-05

    Gamma Ray Bursts (GRBs) are brief, randomly located, releases of gamma-ray energy from unknown celestial sources that occur almost daily. The study of GRBs has undergone a revolution in the past three years due to an international effort of follow-up observations made possible by the instantaneous distribution of reliable GRB coordinate information over the internet provided by NASA's GCN (GRB Coordinates Network). The 3-year LDRD project described here, done in collaboration with the workers responsible for the GCN, was the very first serious system to actively utilize the GCN and thus played a major role in the development of the GCN and the dramatic increase in our understanding of GRBs. The scientific objective of this project was to measure the intensity of any prompt visible radiation accompanying the gamma-ray emission utilizing a small but sensitive robotic telescope that responded to GCN triggers by rapidly taking images of the GCN error box. The instrument developed for this project, LOTIS, was the first of its kind, and the longest running, collecting data on over 75 GRBs during its 3 year running period. The results of LOTIS and the other follow-up programs have now shown that GRBs are at cosmological distances and interact with surrounding material as described by the ''fireball model.'' Visible, prompt, optical counterparts have only been seen in one case and are therefore very rare or much dimmer than the sensitivity of the current instruments. This places numerical limits on the surrounding matter density, and other physical parameters in the GRB environment. A much more sensitive instrument, Super-LOTIS, has been developed for operation at Kitt-Peak.

  15. 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.

  16. Gravitational waves from light cosmic strings: Backgrounds and bursts with large loops

    SciTech Connect

    Hogan, Craig J.

    2006-08-15

    The mean spectrum and burst statistics of gravitational waves produced by a cosmological population of cosmic string loops are estimated using analytic approximations, calibrated with earlier simulations. Formulas are derived showing the dependence of observables on the string tension G{mu}, in the regime where newly-formed loops are relatively large, not very much smaller than the horizon. Large loops form earlier, are more abundant, and generate a more intense stochastic background and more frequent bursts than assumed in earlier background estimates, enabling experiments to probe lighter cosmic strings of interest to string theory. Predictions are compared with instrument noise from current and future experiments, and with confusion noise from known astrophysical gravitational-wave sources such as stellar and massive black hole binaries. In these large-loop models, current data from millisecond pulsar timing already suggests that G{mu} is less than about 10{sup -10}, close to the minimum value where bursts might be detected by Advanced LIGO, and a typical value expected in strings from brane inflation. Because of confusion noise expected from massive black hole binaries, pulsar techniques will not be able to go below about G{mu}{approx_equal}10{sup -11}. LISA will be sensitive to stochastic backgrounds created by strings as light as G{mu}{approx_equal}10{sup -15}, at frequencies where it is limited by confusion noise of Galactic stellar populations; however, for those lightest detectable strings, bursts are rarely detectable. For G{mu}>10{sup -11}, the stochastic background from strings dominates the LISA noise by a large factor, and burst events may also be detectable by LISA, allowing detailed study of loop behavior. Astrophysical confusion might be low enough at 0.1 to 1 Hz to eventually reach G{mu}{approx_equal}10{sup -20} with future interferometer technology.

  17. Gamma-ray burst afterglows as probes of their host galaxies and the cosmos

    NASA Astrophysics Data System (ADS)

    Cucchiara, Antonino

    2010-12-01

    Gamma-ray Bursts (GRBs) represent the sole class of catastrophic phenomena seen over almost the entire history of the Universe. Their extreme luminosities in high energy gamma-ray radiation make them readily detectable, even with relatively small satellite-based detectors, out to the earliest cosmic epochs. Moreover, the brilliance of their fading afterglow light, routinely observed in X-ray, optical, near-infrared, and radio wavelengths, allows them to be exploited -- for hours, days, or weeks -- as cosmic lighthouses, probing the conditions of gas and dust along the line of sight, through their host galaxies and the cosmos at large. Since the November 2004 launch of Swift, this GRB-focused NASA mission has discovered more than 500 GRBs, in almost all cases reporting the burst coordinates to ground-based observers within seconds of the event. The availability of prompt burst positions from Swift, combined with promptly-reported flux measurements from instruments on Swift and an array of ground-based robotic telescopes, have enabled targeted spectroscopic campaigns that have gathered detailed observations of the young, bright afterglows of hundreds of these events. This thesis reports the results of my own efforts over the past 5 years, analyzing imaging and spectroscopic observations of Swift-detected GRBs as triggered according to my own requests, or as gathered from public data archives. In Chapter 2, I discuss our follow-up campaign for GRB090429B, one of our best "extreme redshift" (z > 8) candidates. This burst followed closely on the spectroscopicallyconfirmed z = 8.2 GRB090423, and our multiwavelength observations and SED modeling demonstrate the value and limitation of such studies, in cases where a spectroscopic redshift cannot be gathered in a timely fashion. I also address the importance of such extreme-redshift events from a cosmological perspective. In Chapter 3, I use high-resolution GRB afterglow spectra to study the properties of intervening

  18. 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.

  19. Supernova Shocks and the Gamma-Ray Burst Connection

    NASA Astrophysics Data System (ADS)

    Chevalier, Roger

    We propose projects on the nature of low luminosity gamma-ray bursts (GRBs) and the X-ray emission from strongly interacting supernovae. The class of nearby, low luminosity GRBs with associated supernovae can be studied in detail and probably share physical processes with cosmological bursts. The particular view of low luminosity events to be explored here attributes the X-ray thermal emission to a mildly relativistic flow from a central engine, the early thermal optical emission to the shocked ejecta from a star that has undergone an eruptive event, and the radio emission to the interaction of the mildly relativistic flow with the surrounding medium. We will develop models for this scenario, including the propagation of the collimated flow through the progenitor star and the eventual transition to spherical, nonrelativistic flow in the surrounding medium. The transient event associated with SN 2008D shows similarities to the low luminosity GRBs and will be considered as an especially low energy event. The topic of X- ray supernovae builds on the growing evidence for the interaction of supernovae with very dense circumstellar matter lost within years of the supernova event. A viscous shock is expected even when the shock wave is at moderate optical depth, but the escape of X-ray emission from hot gas is complicated by a number of factors, including changes in absorption by photoionization and Comptonization of energetic photons. There may be circumstances where no emission escapes below 10 keV, but does at 10's of keV. The complex physical situation gives diagnostics on the progenitor star and its dense wind can be obtained. This research is especially relevant to the Swift, Chandra, and XMM missions, as well as the future NuSTAR mission.

  20. 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.

  1. 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.

  2. 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.

  3. SGR J1550-5418 Bursts Detected with the Fermi Gamma-Ray Burst Monitor during Its Most Prolific Activity

    NASA Technical Reports Server (NTRS)

    vanderHorst, A. J.; Kouveliotou, C.; Gorgone, N. M.; Kaneko, Y.; Baring, M. G.; Guiriec, S.; Gogus, E,; Granot, J.; Watts, A. L.; Lin, L.; Bhat, P. N.; Bissaldi, E.; Chaplin, V. L.; Finger, M. H.; Gehrels, N.; Gibby, M. H.; Giles, M. M.; Goldstein, A.; Gruber, D.; Harding, A. K.; McEnery, J.; Meegan, C. A.; Paciesas, W. S.; Preece, R. D.; Wilson-Hodge, C.

    2012-01-01

    We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties.We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J15505418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E(sub peak) and the burst fluence and average flux. For the BB+BBfits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature.We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

  4. SGR J1550-5418 Bursts Detected with the Fermi Gamma-Ray Burst Monitor during its Most Prolific Activity

    NASA Astrophysics Data System (ADS)

    van der Horst, A. J.; Kouveliotou, C.; Gorgone, N. M.; Kaneko, Y.; Baring, M. G.; Guiriec, S.; Göǧüş, E.; Granot, J.; Watts, A. L.; Lin, L.; Bhat, P. N.; Bissaldi, E.; Chaplin, V. L.; Finger, M. H.; Gehrels, N.; Gibby, M. H.; Giles, M. M.; Goldstein, A.; Gruber, D.; Harding, A. K.; Kaper, L.; von Kienlin, A.; van der Klis, M.; McBreen, S.; Mcenery, J.; Meegan, C. A.; Paciesas, W. S.; Pe'er, A.; Preece, R. D.; Ramirez-Ruiz, E.; Rau, A.; Wachter, S.; Wilson-Hodge, C.; Woods, P. M.; Wijers, R. A. M. J.

    2012-04-01

    We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties. We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J1550-5418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E peak and the burst fluence and average flux. For the BB+BB fits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high-temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature. We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

  5. SGR J1550-5418 BURSTS DETECTED WITH THE FERMI GAMMA-RAY BURST MONITOR DURING ITS MOST PROLIFIC ACTIVITY

    SciTech Connect

    Van der Horst, A. J.; Finger, M. H.; Kouveliotou, C.; Kaneko, Y.; Goegues, E.; Lin, L.; Baring, M. G.; Guiriec, S.; Bhat, P. N.; Chaplin, V. L.; Goldstein, A.; Granot, J.; Watts, A. L.; Bissaldi, E.; Gruber, D.; Gehrels, N.; Harding, A. K.; Gibby, M. H.; Giles, M. M.; and others

    2012-04-20

    We have performed detailed temporal and time-integrated spectral analysis of 286 bursts from SGR J1550-5418 detected with the Fermi Gamma-ray Burst Monitor (GBM) in 2009 January, resulting in the largest uniform sample of temporal and spectral properties of SGR J1550-5418 bursts. We have used the combination of broadband and high time-resolution data provided with GBM to perform statistical studies for the source properties. We determine the durations, emission times, duty cycles, and rise times for all bursts, and find that they are typical of SGR bursts. We explore various models in our spectral analysis, and conclude that the spectra of SGR J1550-5418 bursts in the 8-200 keV band are equally well described by optically thin thermal bremsstrahlung (OTTB), a power law (PL) with an exponential cutoff (Comptonized model), and two blackbody (BB) functions (BB+BB). In the spectral fits with the Comptonized model, we find a mean PL index of -0.92, close to the OTTB index of -1. We show that there is an anti-correlation between the Comptonized E{sub peak} and the burst fluence and average flux. For the BB+BB fits, we find that the fluences and emission areas of the two BB functions are correlated. The low-temperature BB has an emission area comparable to the neutron star surface area, independent of the temperature, while the high-temperature BB has a much smaller area and shows an anti-correlation between emission area and temperature. We compare the properties of these bursts with bursts observed from other SGR sources during extreme activations, and discuss the implications of our results in the context of magnetar burst models.

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

    NASA Astrophysics Data System (ADS)

    Yu, Yun-Wei

    2014-12-01

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

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

    SciTech Connect

    Yu, Yun-Wei

    2014-12-01

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

  8. Persistent X-ray emission from a gamma-ray burst source

    NASA Technical Reports Server (NTRS)

    Grindlay, J. E.; Cline, T.; Desai, U. D.; Teegarden, B. J.; Pizzichini, G.; Evans, W. D.; Laros, J. G.; Hurley, K. C.; Niel, M.; Klebesadel, R. W.

    1982-01-01

    A quiescent X-ray source detected with the Einstein X-ray Observatory in a location consistent with that of an intense gamma ray burst is shown to be also consistent with the location of the 1928 optical transient, the likely optical counterpart of the gamma ray burst source GBS0117-29. The system appears to be underluminous in X-rays by a factor of 10; possible reasons for this are discussed. The observed X-ray flux would require an accretion rate of about 10 to the -14th (d/1 kpc/)-squared solar masses per year, which is probably too low to be consistent with published nuclear flash models for gamma bursts, unless the distance is substantially greater than about 1 kpc or the burst recurrence time is greater than about 50 yrs, or the accretion rate is highly variable. Such a long recurrence time appears to be inconsistent with the detection of the optical burst.

  9. Gravitational waves from broken cosmic strings: The bursts and the beads

    SciTech Connect

    Leblond, Louis; Shlaer, Benjamin; Siemens, Xavier

    2009-06-15

    We analyze the gravitational wave signatures of a network of metastable cosmic strings. We consider the case of cosmic string instability to breakage, with no primordial population of monopoles. This scenario is well motivated from grand unified theories and string-theoretic models with an inflationary phase below the grand unified theories/string scale. The network initially evolves according to a scaling solution, but with breakage events resulting from confined monopoles (beads) being pair produced and accelerated apart. We find these ultrarelativistic beads to be a potent source of gravitational wave bursts, detectable by initial LIGO, advanced LIGO, and LISA. Indeed, advanced LIGO could observe bursts from strings with tensions as low as G{mu}{approx}10{sup -12}. In addition, we find that ultrarelativistic beads produce a scale-invariant stochastic background detectable by LIGO, LISA, and pulsar timing experiments. The stochastic background is scale invariant up to the Planckian frequencies. This phenomenology provides new constraints and signatures of cosmic strings that disappear long before the present day.

  10. HOST GALAXIES AS GAMMA-RAY BURST DISTANCE INDICATORS

    SciTech Connect

    D. BAND; ET AL

    2001-01-01

    We calculate the distributions of the total burst energy, the peak luminosity and the X-ray afterglow energy using burst observations and distances to the associated host galaxies. To expand the sample, we include redshift estimates for host galaxies without spectroscopic redshifts. The methodology requires a model of the host galaxy population; we find that in the best model the burst rate is proportional to the host galaxy luminosity at the time of the burst.

  11. Implications of the BATSE data for a helocentric origin of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Horack, J. M.; Koshut, T. M.; Mallozzi, R. S.; Storey, S. D.; Emslie, A. G.

    1994-01-01

    Several possible models have been suggested to explain the observed distribution of gamma-ray bursts: heliocentric distributions such as the Oort cloud, large galactic halos, and cosmological models. We report here on an investigation into the implications of the Burst and Transient Source Experiment (BATSE) gamma-ray burst distribution (Meegan et al. 1992a) data on the possible helocentric origin of gamma-ray bursts. We find no statistically significant anisotropy in the angular distribution of the bursts in a Sun-referenced coordinate system; there is no dipole moment in the direction of the Sun, and no quardrupole moment associated with the ecliptic plane. We have employed direct analytic calculations and Monte Carlo simulations of sources in the Oort cloud to constrain possible helicentric burst distributions. These can produce distributions consistent with the observed angular isotropy, the meal value of V/V(sub max), and the observed C/C(sub min) distribution of BATSE, and provide limits to burst energy of a few times approximately 10(exp 27) ergs. However, the agreement of the heliocentric C/C(sub min) distributions with the BATSE data is attributable to the relatively limited sampling of strong, nearby bursts. These bursts are known from observation to be homogeneously distributed, yet the density of sources in the Oort cloud is not constant in this region. Integral number-intensity distributions from the Oort cloud for larger numbers of bursts cannot reproduce the known homogeneity of the strong bursts without modification to the computed cometary number density and are therefore unlikely explanations of the gamma-ray burst distribution.

  12. Modeling Photodisintegration-induced TeV Photon Emission from Low-luminosity Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Liu, Xue-Wen; Wu, Xue-Feng; Lu, Tan

    2012-05-01

    Ultra-high-energy cosmic-ray heavy nuclei have recently been considered as originating from nearby low-luminosity gamma-ray bursts that are associated with Type Ibc supernovae. Unlike the power-law decay in long duration gamma-ray bursts, the light curve of these bursts exhibits complex UV/optical behavior: shock breakout dominated thermal radiation peaks at about 1 day, and, after that, nearly constant emission sustained by radioactive materials for tens of days. We show that the highly boosted heavy nuclei at PeV energy interacting with the UV/optical photon field will produce considerable TeV photons via the photodisintegration/photo-de-excitation process. It was later predicted that a thermal-like γ-ray spectrum peaks at about a few TeV, which may serve as evidence of nucleus acceleration. The future observations by the space telescope Fermi and by the ground atmospheric Cherenkov telescopes such as H.E.S.S., VERITAS, and MAGIC will shed light on this prediction.

  13. A COMPLETE SAMPLE OF BRIGHT SWIFT LONG GAMMA-RAY BURSTS. I. SAMPLE PRESENTATION, LUMINOSITY FUNCTION AND EVOLUTION

    SciTech Connect

    Salvaterra, R.; Campana, S.; Vergani, S. D.; Covino, S.; D'Avanzo, P.; Fugazza, D.; Ghirlanda, G.; Ghisellini, G.; Melandri, A.; Sbarufatti, B.; Tagliaferri, G.; Nava, L.; Flores, H.; Piranomonte, S.

    2012-04-10

    We present a carefully selected sub-sample of Swift long gamma-ray bursts (GRBs) that is complete in redshift. The sample is constructed by considering only bursts with favorable observing conditions for ground-based follow-up searches, which are bright in the 15-150 keV Swift/BAT band, i.e., with 1-s peak photon fluxes in excess to 2.6 photons s{sup -1} cm{sup -2}. The sample is composed of 58 bursts, 52 of them with redshift for a completeness level of 90%, while another two have a redshift constraint, reaching a completeness level of 95%. For only three bursts we have no constraint on the redshift. The high level of redshift completeness allows us for the first time to constrain the GRB luminosity function and its evolution with cosmic times in an unbiased way. We find that strong evolution in luminosity ({delta}{sub l} = 2.3 {+-} 0.6) or in density ({delta}{sub d} = 1.7 {+-} 0.5) is required in order to account for the observations. The derived redshift distributions in the two scenarios are consistent with each other, in spite of their different intrinsic redshift distributions. This calls for other indicators to distinguish among different evolution models. Complete samples are at the base of any population studies. In future works we will use this unique sample of Swift bright GRBs to study the properties of the population of long GRBs.

  14. 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.

  15. Gamma-ray burst observations with new generation imaging atmospheric Cerenkov Telescopes in the FERMI era

    SciTech Connect

    Covino, S.; Campana, S.; Galante, N.; Gaug, M.; Longo, F.; Scapin, V.

    2009-04-08

    After the launch and successful beginning of operations of the FERMI satellite, the topics related to high-energy observations of gamma-ray bursts have obtained a considerable attention by the scientific community. Undoubtedly, the diagnostic power of high-energy observations in constraining the emission processes and the physical conditions of gamma-ray burst is relevant. We briefly discuss how gamma-ray burst observations with ground-based imaging array Cerenkov telescopes, in the GeV-TeV range, can compete and cooperate with FERMI observations, in the MeV-GeV range, to allow researchers to obtain a more detailed and complete picture of the prompt and afterglow phases of gamma-ray bursts.

  16. 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.

  17. Source position loci for the gamma-ray bursts recorded October 20 and November 10, 1977

    NASA Technical Reports Server (NTRS)

    Estulin, I. V.; Cline, T. L.; Vedrenne, G.; Kuznetsov, A. V.; Mersov, G. A.; Niel, M.; Novak, B. L.; Hurley, K.

    1979-01-01

    Further constraints are imposed on the sites of the gamma-ray bursts recorded Oct. 20 and Nov. 10, 1977 with the Prognoz 6 satellite and the Helios 2 spacecraft. The loci of the burst sources are 1.7-arcmin-wide bands in which no X-ray sources, pulsars, supernova remnants, or galaxies brighter than 13m occur.

  18. THERMAL RADIATION FROM GAMMA-RAY BURST JETS

    SciTech Connect

    Mizuta, Akira; Nagataki, Shigehiro; Aoi, Junichi

    2011-05-01

    In this study, the light curves and spectrum of the photospheric thermal radiation from ultrarelativistic gamma-ray burst (GRB) jets are calculated using two-dimensional relativistic hydrodynamic simulations of jets from a collapsar. As the jet advances, the density around the head of the jet decreases, and its Lorentz factor reaches as high as 200 at the photosphere and 400 inside the photosphere. For an on-axis observer, the photosphere appears concave due to the low density and high beaming factor of the jet. The luminosity varies because of the abrupt change in the position of the photosphere due to the internal structure of the jet. Comparing our results with GRB 090902B, the flux level of the thermal-like component is similar to our model, although the peak energy appears slightly higher (but still within a factor of two). From the comparison, we estimate that the bulk Lorentz factor of GRB 090902B is {Gamma} {approx} 2.4 x 10{sup 2}(r/10{sup 12} cm), where r is the radius of the photosphere. The spectrum for an on-axis observer is harder than that for an off-axis observer. There is a time lag of a few seconds for high energy bands in the light curve. This may be the reason for the delayed onset of GeV emission seen in GRB 080916C. The spectrum below the peak energy is a power law and the index is 2.3-2.6, which is softer than that of a single temperature Planck distribution but still harder than that of the typical value of the observed spectrum.

  19. 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.

  20. 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.