In:
The Astrophysical Journal, American Astronomical Society, Vol. 889, No. 2 ( 2020-02-01), p. 110-
Abstract:
We have performed a systematic study of gamma-ray bursts (GRBs), which have various values in the peak energy of the νF ν spectrum of prompt emission, E peak , observed by the Swift /Burst Alert Telescope (BAT) and Fermi /Gamma-ray Burst Monitor, investigating their prompt and X-ray afterglow emissions. We cataloged long-lasting GRBs observed by Swift between 2004 December and 2014 February in three categories according to the classification by Sakamoto et al.: X-ray flashes (XRFs), X-ray-rich GRBs (XRRs), and classical GRBs (C-GRBs). We then derived , as well as if viable, of the Swift spectra of their prompt emission. We also analyzed their X-ray afterglows and found that GRB events with a lower , i.e., softer GRBs, are fainter in 0.3–10 keV X-ray luminosity and decay more slowly than harder GRBs. The intrinsic event rates of the XRFs, XRRs, and C-GRBs were calculated using the Swift /BAT trigger algorithm. Those of the XRRs and XRFs are larger than that of the C-GRBs. If we assume that the observational diversity of E peak is explained using the off-axis model, these results yield a jet half-opening angle of Δ θ ∼ 0.°3, and a variance of the observing angles θ obs ≲ 0.°6. This implies that this tiny variance would be responsible for the E peak diversity observed by Swift /BAT, which is unrealistic. Therefore, we conclude that the E peak diversity is not explained with the off-axis model, but is likely to originate from some intrinsic properties of the jets.
Type of Medium:
Online Resource
ISSN:
0004-637X
,
1538-4357
DOI:
10.3847/1538-4357/ab6167
Language:
Unknown
Publisher:
American Astronomical Society
Publication Date:
2020
detail.hit.zdb_id:
2207648-7
detail.hit.zdb_id:
1473835-1
SSG:
16,12
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