2018A&A...616A.138O


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST07:16:36

2018A&A...616A.138O - Astronomy and Astrophysics, volume 616A, 138-138 (2018/8-1)

Characterization of gamma-ray burst prompt emission spectra down to soft X-rays.

OGANESYAN G., NAVA L., GHIRLANDA G. and CELOTTI A.

Abstract (from CDS):

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

Abstract Copyright: © ESO 2018

Journal keyword(s): gamma-ray burst: general - radiation mechanisms: non-thermal

Simbad objects: 34

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Number of rows : 34

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 GRB 100814A gB 01 29 53.61 -17 59 43.6           ~ 149 0
2 GRB 100906A gB 01 54 44.19 +55 37 49.8           ~ 156 0
3 GRB 070616 gB 02 08 36.430 +56 56 44.91           ~ 68 0
4 GRB 070721B gB 02 12 32.98 -02 11 39.8           ~ 98 0
5 GRB 100619A gB 05 38 28.0 -27 00 02           ~ 41 0
6 GRB 100728A gB 05 55 01.99 -15 15 20.1           ~ 99 0
7 GRB 080928 gB 06 20 16.85 -55 11 59.3           ~ 128 1
8 GRB 150724A gB 06 30 14.47 -19 09 52.0           ~ 9 0
9 GRB 141031A gB 08 34 26.05 -59 10 05.8           ~ 22 0
10 GRB 100704A gB 08 54 33.92 -24 12 09.7           ~ 71 0
11 GRB 140206A gB 09 41 16.90 +66 45 42.7           ~ 79 0
12 GRB 061121 gB 09 48 54.570 -13 11 42.68 17.19 17.71 17.02     ~ 287 0
13 GRB 121217A gB 10 14 50.32 -62 21 03.3           ~ 45 0
14 GRB 111123A gB 10 19 23.14 -20 38 41.1           ~ 48 0
15 GRB 110205A gB 10 58 31.12 +67 31 31.2           ~ 147 0
16 GRB 130907A gB 14 23 34.03 +45 36 27.1           ~ 73 0
17 GRB 060814 gB 14 45 21.480 +20 35 11.80           ~ 185 0
18 GRB 080906 gB 15 12 13 -80 32.4           ~ 43 0
19 GRB 060510B gB 15 56 29.200 +78 34 12.00           ~ 131 0
20 GRB 110102A gB 16 23 31.41 +07 36 49.8           ~ 43 0
21 GRB 130606A gB 16 37 35.12 +29 47 46.4           ~ 114 0
22 GRB 090715B gB 16 45 21.58 +44 50 20.1           ~ 98 0
23 GRB 111103B gB 17 42 46.37 +01 36 36.3           ~ 32 0
24 GRB 100413A gB 17 44 53.22 +15 50 02.4           ~ 47 0
25 GRB 081008 gB 18 39 52.40 -57 25 58.8           ~ 156 0
26 GRB 140512A gB 19 17 28.81 -15 05 39.5           ~ 66 0
27 GRB 090709A gB 19 19 46.70 +60 43 40.8           ~ 96 0
28 GRB 100725B gB 19 20 07 +76 57.3           ~ 41 0
29 GRB 130514A gB 19 45 07.33 -07 58 41.1           ~ 42 0
30 GRB 121123A gB 20 29 16.30 -11 51 35.6           ~ 41 0
31 GRB 140108A gB 21 40 26.77 +58 44 41.4           ~ 35 0
32 GRB 151021A gB 22 30 34.43 -33 11 50.3           ~ 33 0
33 GRB 110119A gB 23 14 21 +05 58.9           ~ 34 0
34 GRB 140323A gB 23 47 50.31 -79 54 16.4           ~ 22 0

    Equat.    Gal    SGal    Ecl

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2020.07.13-07:16:36

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