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


Query : 2018A&A...616A.138O

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

goto Full paper

goto View the references in ADS

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 - 2022
#notes
1 Fermi bn100814160 gB 01 29 53.61 -17 59 43.6           ~ 166 0
2 Fermi bn100906576 gB 01 54 44.19 +55 37 49.8           ~ 176 0
3 GRB 070616 gB 02 08 36.430 +56 56 44.91           ~ 71 0
4 GRB 070721B gB 02 12 32.98 -02 11 39.8           ~ 109 0
5 Fermi bn100619015 gB 05 38 28.0 -27 00 02           ~ 44 0
6 Fermi bn100728095 gB 05 55 02.00 -15 15 20.2           ~ 115 0
7 Fermi bn080928628 gB 06 20 16.85 -55 11 59.3           ~ 148 0
8 GRB 150724A gB 06 30 14.48 -19 09 51.7           ~ 10 0
9 GRB 141031A gB 08 34 25.96 -59 10 05.8           ~ 25 0
10 Fermi bn100704149 gB 08 54 33.92 -24 12 09.7           ~ 80 0
11 Fermi bn140206304 gB 09 41 16.90 +66 45 42.7           ~ 101 0
12 GRB 061121 gB 09 48 54.570 -13 11 42.68 17.19 17.71 17.02     ~ 305 0
13 Fermi bn121217313 gB 10 14 50.32 -62 21 03.3           ~ 51 0
14 GRB 111123A gB 10 19 23.17 -20 38 41.9           ~ 62 0
15 GRB 110205A gB 10 58 31.12 +67 31 31.2           ~ 167 0
16 GRB 130907A gB 14 23 34.03 +45 36 27.1           ~ 87 0
17 GRB 060814 gB 14 45 21.480 +20 35 11.80           ~ 203 0
18 GRB 080906 gB 15 12 13 -80 32.4           ~ 49 0
19 GRB 060510B gB 15 56 29.200 +78 34 12.00           ~ 137 0
20 Fermi bn110102788 gB 16 23 31.41 +07 36 49.8           ~ 49 0
21 GRB 130606A gB 16 37 35.12 +29 47 46.4           ~ 134 0
22 GRB 090715B gB 16 45 21.59 +44 50 20.1           ~ 113 0
23 GRB 111103B gB 17 42 46.37 +01 36 36.3           ~ 36 0
24 Fermi bn100413732 gB 17 44 53.22 +15 50 02.4           ~ 52 0
25 Fermi bn081008832 gB 18 39 52.40 -57 25 58.8           ~ 180 0
26 Fermi bn140512814 gB 19 17 28.81 -15 05 39.5           ~ 85 0
27 GRB 090709A gB 19 19 46.70 +60 43 40.8           ~ 106 0
28 Fermi bn100725475 gB 19 20 07 +76 57.3           ~ 46 0
29 GRB 130514A gB 19 45 07.33 -07 58 41.1           ~ 53 0
30 Fermi bn121123421 gB 20 29 16.30 -11 51 35.6           ~ 46 0
31 Fermi bn140108721 gB 21 40 26.77 +58 44 41.4           ~ 42 0
32 GRB 151021A gB 22 30 34.43 -33 11 50.4           ~ 45 0
33 Fermi bn110119931 gB 23 14 21 +05 58.9           ~ 40 0
34 Fermi bn140323433 gB 23 47 50.31 -79 54 16.4           ~ 26 0

To bookmark this query, right click on this link: simbad:objects in 2018A&A...616A.138O and select 'bookmark this link' or equivalent in the popup menu


2022.08.10-06:57:42

© Université de Strasbourg/CNRS

    • Contact