Document Type

Article

Publication Date

12-14-2018

Publication Title

Astrophysical Journal

Volume

869

Issue

2

First page number:

1

Last page number:

17

Abstract

The prompt emission phase of gamma-ray bursts (GRBs) exhibits two distinct patterns of the peak energy (E p ) evolution, i.e., time-resolved spectral analyses of νF ν spectra of broad pulses reveal (1) "hard-to-soft" and (2) "flux-tracking" patterns of E p evolution in time, the physical origin of which still remains not well understood. We show here that these two patterns can be successfully reproduced within a simple physical model invoking synchrotron radiation in a bulk-accelerating emission region. We show further that the evolution patterns of the peak energy have, in fact, direct connections to the existence of two different (positive or negative) types of spectral lags, seen in the broad pulses. In particular, we predict that (1) only the positive type of spectral lags is possible for the hard-to-soft evolution of the peak energy, (2) both the positive and negative type of spectral lags can occur in the case of the flux-tracking pattern of the peak energy, (3) for the flux-tracking pattern the peak location of the flux light curve slightly lags behind the peak of the E p evolution with time if the spectral lags are positive, and (4) in the case of the flux-tracking pattern double-peaked broad pulses can appear in the light curves, the shape of which is energy dependent.

Keywords

Gamma-ray burst: General; Radiation mechanisms: Non-thermal; Relativistic processes

Disciplines

Astrophysics and Astronomy

File Format

PDF

File Size

985 Kb

Language

English

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