2009A&A...508..173A


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.18CEST05:18:59

2009A&A...508..173A - Astronomy and Astrophysics, volume 508, 173-180 (2009/12-2)

Extremely energetic Fermi gamma-ray bursts obey spectral energy correlations.

AMATI L., FRONTERA F. and GUIDORZI C.

Abstract (from CDS):

The origin, reliability, and dispersion of the Ep,i-Eiso and other spectral energy correlations is a highly debated topic in GRB astrophysics. GRB080916C, with its enormous radiated energy (Eiso∼1055erg in the 1keV-10GeV cosmological rest-frame energy band) and its intense GeV emission measured by Fermi, provides a unique opportunity to investigate this issue. In our analysis, we also study another extremely energetic event, GRB090323, more recently detected and localized by Fermi/LAT, whose radiated energy is comparable to that of GRB080916C in the 1keV-10MeV energy range. Based on Konus/WIND and Fermi spectral measurements, we find that both events are fully consistent with the Ep,i-Eiso correlation (updated to include 95 GRBs with the data available as of April 2009), thus further confirming and extending it, and providing evidence against a possible flattening or increased dispersion at very high energies. This also suggests that the physics behind the emission of peculiarly bright and hard GRBs is the same as for medium-bright and soft-weak long events (XRFs), which all follow the correlation. In addition, we find that the normalization of the correlation obtained by considering these two GRBs and the other long ones for which Ep,i was measured to high accuracy by the Fermi/GBM are fully consistent with those obtained by other instruments (e.g., BeppoSAX, Swift, Konus/WIND), thus indicating that the correlation is not affected significantly by ``data truncation'' because of detector thresholds and limited energy bands. A Fermi/GBM accurate estimate of the peak energy of a very bright and hard short GRB with a measured redshift, GRB090510, provides robust evidence that short GRBs do not follow the Ep,i-Eiso correlation and that the Ep,i-Eiso plane can be used to discriminate between, and understand, the two classes of events. Prompted by the extension of the spectrum of GRB080916C to several GeV (in the cosmological rest-frame) without any excess or cut-off, we also investigated whether the evaluation of Eiso in the commonly adopted 1 keV-10 MeV energy band may bias the Ep,i-Eiso correlation and/or contribute to its scatter. By computing Eiso from 1keV to 10GeV, the slope of the correlation becomes slightly flatter, while its dispersion does not change significantly. Finally, we find that GRB080916C is also consistent with most of the other spectral energy correlations derived from it, with the possible exception of the Ep,i-Eiso-tb correlation.

Abstract Copyright:

Journal keyword(s): gamma rays: bursts - gamma rays: observations

Simbad objects: 26

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Number of rows : 26

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 GRB 081222 gB 01 30 57.76 -34 05 44.0           ~ 155 0
2 GRB 080913 gB 04 22 57.90 -25 07 38.6           ~ 177 0
3 GRB 081118 gB 05 30 22.28 -43 18 03.1           ~ 64 0
4 GRB 081121 gB 05 57 07.70 -60 36 42.1           ~ 113 0
5 GRB 090328 gB 06 02 39.69 -41 52 55.1           ~ 145 1
6 GRB 080916C gB 07 59 23.24 -56 38 16.8           ~ 324 0
7 GRB 081028 gB 08 07 34.40 +02 18 16.8           ~ 96 0
8 GRB 020127 gB 08 15 05.8 +36 44 31           ~ 60 0
9 GRB 090102 gB 08 32 59.50 +33 06 25.7           ~ 188 0
10 GRB 090423 gB 09 55 33.19 +18 08 57.7           ~ 317 0
11 GRB 080603B gB 11 46 07.46 +68 03 38.5           ~ 118 0
12 GRB 090424 gB 12 38 07.40 +16 49 45.9           ~ 209 0
13 GRB 090323 gB 12 42 50.28 +17 03 11.9           ~ 187 1
14 GRB 080607 gB 12 59 47.14 +15 55 09.6           ~ 212 0
15 GRB 080721 gB 14 57 55.76 -11 43 24.9           ~ 142 0
16 GRB 080605 gB 17 28 30.04 +04 00 56.9           ~ 155 0
17 GRB 090418 gB 17 57 15.2 +33 24 22           ~ 22 0
18 GRB 081008 gB 18 39 52.40 -57 25 58.8           ~ 164 0
19 SN 1998bw SN* 19 35 03.17 -52 50 46.1   14.09       SNIc 1683 2
20 GRB 071003 gB 20 07 24.50 +10 56 48.8           ~ 144 0
21 GRB 080514B gB 21 31 22.61 +00 42 30.3           ~ 59 0
22 GRB 080413B gB 21 44 34.62 -19 58 51.2           ~ 152 0
23 GRB 090510 gB 22 14 12.60 -26 35 51.1           ~ 426 1
24 GRB 080916A gB 22 25 09.30 -57 01 33.7           ~ 142 0
25 SN 2008hw SN* 22 39 50.39 -40 08 49.1           SNIc 149 1
26 GRB 080810 gB 23 47 08.00 +00 18 35.1           ~ 186 0

    Equat.    Gal    SGal    Ecl

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