Document Type

Article

Publication Date

10-16-2019

Publication Title

Astrophysical Journal

Publisher

American Astronomical Society

Volume

884

Issue

2

First page number:

1

Last page number:

9

Abstract

The characteristics of the spectral evolution of the prompt emission of gamma-ray bursts (GRBs), which are closely related to the radiation mechanism (synchrotron or photosphere), are still an unsolved subject. Here, by performing the detailed time-resolved spectral fitting of GRB 131231A, which has a very bright and well-defined single pulse, some interesting spectral evolution features have been found. (i) Both the low-energy spectral index α and the peak energy E p exhibit the "flux-tracking" pattern ("double-tracking" characteristics). (ii) The parameter relations, i.e., F (the energy flux)-α, F–E p, and E p–α, along with the analogous Yonetoku E p–L γ,iso relation for the different time-resolved spectra, show strong monotonous (positive) correlations, both in the rising and the decaying phases. (iii) The values of α do not exceed the synchrotron limit (α = −2/3) in all slices across the pulse, favoring the synchrotron origin. We argue that the one-zone synchrotron emission model with the emitter streaming away at a large distance from the central engine can explain all of these special spectral evolution characteristics.

Keywords

Gamma-ray burst: general; Radiation mechanisms: non-thermal

Disciplines

Stars, Interstellar Medium and the Galaxy

File Format

pdf

File Size

882.62 KB

Language

English

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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