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Title: GRB 190114C: Fireball Energy Budget and Radiative Efficiency Revisited
Abstract The jet composition of gamma-ray bursts (GRBs), as well as how efficiently the jet converts its energy to radiation, are long-standing problems in GRB physics. Here, we reported a comprehensive temporal and spectral analysis of the TeV-emitting bright GRB 190114C. Its high fluence (∼4.4 × 10−4erg cm−2) allows us to conduct the time-resolved spectral analysis in great detail and study their variations down to a very short timescale (∼0.1 s) while preserving a high significance. Its prompt emission consists of three well-separated pulses. The first two main pulses (P1andP2) exhibit independently strong thermal components, starting from the third pulse (P3) and extending to the entire afterglow, the spectra are all nonthermal, and the synchrotron plus Compton upscattering model well interprets the observation. By combining the thermal (P1andP2) and the nonthermal (P3) observations based on two different scenarios (global and pulse properties) and following the method described in Zhang et al., we measure the fireball parameters and GRB radiative efficiency with little uncertainties for this GRB. A relevantly high GRB radiative efficiency is obtained based on both the global and pulse properties, suggesting that if GRBs are powered by fireballs, the efficiency can sometimes be high. More interestingly, though the observed parameters are individually different (e.g., the amount of mass loadingM), the radiative efficiency obtained fromP1(ηγ= 36.0% ± 6.5%) andP2(ηγ= 41.1% ± 1.9%) is roughly the same, which implies that the central engine of the same GRB has some common properties.  more » « less
Award ID(s):
2011759
PAR ID:
10548246
Author(s) / Creator(s):
;
Publisher / Repository:
American Astronomical Society
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
972
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
195
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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