GAMMA-RAY BURSTS: PROGRESS, PROBLEMS &amp; PROSPECTS

Zhang, Bing; Mészáros, P.

doi:10.1142/s0217751x0401746x

Cited by 798 publications

(868 citation statements)

References 500 publications

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“…A pure power-law provides a reasonably good fit to the data with a χ 2 of 4.5/5 d.o.f. The resulting power-law index of β opt = 1.46 +0.07 −0.08 , however would be surprisingly red, both theoretically (Sari et al 1998) and observationally (Kann et al , 2009a A spectral index of β opt ∼ 1.2 is only consistent with temporal index α = 2.27 ± 0.04 in a post jet break evolution and the ISM or wind, slow cooling case in the spectral regime above the cooling frequency ν opt > ν c (Sari et al 1998;Chevalier & Li 2000;Zhang & Mészáros 2004). In this case the electron energy index p is p = 2β = 2.4 +0.4 −0.4 as obtained from the spectral index.…”

Section: Spectral Energy Distributionmentioning

confidence: 94%

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

McBreen

Krühler

Rau

et al. 2010

A&A

116

100

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Aims. Fermi can measure the spectral properties of gamma-ray bursts over a very large energy range and is opening a new window on the prompt emission of these energetic events. Localizations by the instruments on Fermi in combination with follow-up by Swift provide accurate positions for observations at longer wavelengths leading to the determination of redshifts, the true energy budget, host galaxy properties and facilitate comparison with pre-Fermi bursts. Methods. Multi-wavelength follow-up observations were performed on the afterglows of four bursts with high energy emission detected by Fermi/LAT: GRB 090323, GRB 090328, GRB 090510 and GRB 090902B. They were obtained in the optical/near-infrared bands with GROND mounted at the MPG/ESO 2.2 m telescope and additionally of GRB 090323 in the optical with the 2 m telescope in Tautenburg, Germany. Three of the events are classified as long bursts while GRB 090510 is a well localized short GRB with GeV emission. In addition, host galaxies were detected for three of the four bursts. Spectroscopic follow-up was initiated with the VLT for GRB 090328 and GRB 090510. Results. The afterglow observations in 7 bands are presented for all bursts and their host galaxies are investigated. Knowledge of the distance and the local dust extinction enables comparison of the afterglows of LAT-detected GRBs with the general sample. The spectroscopic redshifts of GRB 090328 and GRB 090510 were determined to be z = 0.7354 ± 0.0003 and z = 0.903 ± 0.001 and dust corrected star-formation rates of 4.8 M yr −1 and 0.60 M yr −1 were derived for their host galaxies, respectively. Conclusions. The afterglows of long bursts exhibit power-law decay indices (α) from less than 1 to ∼2.3 and spectral indices (β opt ) values from 0.65 to ∼1.2 which are fairly standard for GRB afterglows. Constraints are placed on the jet half opening angles of < ∼ 2.1 • to > ∼ 6.4 • , which allows limits to be placed on the beaming corrected energies. These range from < ∼ 5 × 10 50 erg to the one of the highest values ever recorded, > ∼ 2.2 × 10 52 erg for GRB 090902B, and are not consistent with a standard candle. The extremely energetic long Fermi bursts have optical afterglows which lie in the top half of the brightness distribution of all optical afterglows detected in the Swift era or even in the top 5% if incompleteness is considered. The properties of the host galaxies of these LAT detected bursts in terms of extinction, star formation rates and masses do not appear to differ from previous samples.

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Section: Spectral Energy Distributionmentioning

confidence: 94%

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

McBreen

Krühler

Rau

et al. 2010

A&A

116

100

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“…Leading candidates as sources of high energy neutrinos are also Gamma Ray Bursts (GRB) [20,21,22,23]. It is possible that individual GRB emits neutrino fluences that are sufficiently high to give detectable rates in the neutrino telescopes.…”

Section: The Gamma-ray Skymentioning

confidence: 99%

Perspectives of high-energy neutrino astronomy

Lipari

2006

Nuclear Instruments and Methods in Physics Research Section A:

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“…In addition, a large ordered magnetic field may be induced by the angular momentum of the accretion disk (Zhang & Mészáros 2004). Energetic outflows develop, which are beamed perpendicular to the accretion disk and along the black hole's rotation axis.…”

Section: Introductionmentioning

confidence: 99%

High energy emission and polarisation limits for the INTEGRAL burst GRB 061122

McGlynn

Foley

McBreen

et al. 2009

A&A

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Context. GRB 061122 is one of the brightest GRBs detected within INTEGRAL's field of view to date, with a peak flux (20-200 keV) of 32 photons cm −2 s −1 and fluence of 2 × 10 −5 erg cm −2 . The Spectrometer aboard INTEGRAL, SPI, can measure linear polarisation in bright GRBs through the process of Compton scattering in the Germanium detectors. Polarisation measurements of the prompt emission are relatively rare. The spectral and polarisation results can be combined to provide vital information about the circumburst region. Aims. The two γ-ray detectors on INTEGRAL were used to investigate the spectral characteristics of GRB 061122. A search for linear polarisation in the prompt emission was carried out on GRB 061122 using the SPI multiple event data in the energy range 100 keV-1 MeV. The X-ray properties were examined using data from the X-Ray Telescope (XRT) on Swift. Methods. The γ-ray spectral and temporal properties of GRB 061122 were determined using IBIS and SPI. The afterglow properties were obtained using XRT. The multiple event data of GRB 061122 from SPI were analysed and compared with the predicted instrument response obtained from Monte-Carlo simulations using the GEANT 4 INTEGRAL mass model. The χ 2 distributions between the real and simulated data as a function of the percentage polarisation and polarisation angle were calculated and limits on the level and angle of polarisation were obtained from the best-fit value of χ 2 . Results. The prompt spectrum was best fit by a combination of a blackbody and a power-law model (the quasithermal model), with evidence for high energy emission continuing above 8 MeV. A pseudo-redshift value of pz = 0.95 ± 0.18 was determined using the spectral fit parameters. The isotropic energy at this pseudo-redshift is 8.5 × 10 52 erg. The jet opening angle was estimated to be smaller than 2.8 • or larger than 11.9 • from the X-ray lightcurve. An upper limit of 60% polarisation was determined for the prompt emission of GRB 061122, using the multiple event data from the spectrometer on INTEGRAL. Conclusions. The high energy emission observed in the spectrum may be due to the reverse shock interacting with the GRB ejecta when it is decelerated by the circumburst medium. This behaviour has been observed in a small fraction of GRBs to date, but is expected to be more commonly observed by the Fermi Gamma-ray Space Telescope. The conditions for polarisation are met if the jet opening angle is less than 2.8 • , but further constraints on the level of polarisation are not possible.

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GAMMA-RAY BURSTS: PROGRESS, PROBLEMS & PROSPECTS

Cited by 798 publications

References 500 publications

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

Optical and near-infrared follow-up observations of fourFermi/LAT GRBs: redshifts, afterglows, energetics, and host galaxies

Perspectives of high-energy neutrino astronomy

High energy emission and polarisation limits for the INTEGRAL burst GRB 061122

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