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Sharp Decay of the Internal Plateau in Gamma-Ray Bursts: The Effect of a Cocoon's Thermal Photons on the Jet Emission.
- Source :
-
Astrophysical Journal . 1/1/2024, Vol. 960 Issue 1, p1-7. 7p. - Publication Year :
- 2024
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Abstract
- Sub-TeV or TeV γ -rays have been convincingly detected in the afterglows of some gamma-ray bursts (GRBs). The relativistic jet associated with GRBs may be surrounded by a cocoon and thus the thermal photons of the cocoon pervading the emission region of the jet can be upscattered to the very-high-energy regime (e.g., sub-TeV/TeV) by the electrons in the jet. In this scenario, the electrons in the jet cool down and thus the jet emission in the low-energy regime, e.g., the X-ray or optical, may be suppressed. In this paper, we study the effect of the cocoon's thermal photons on the jet emission in the low-energy regime. We find that the jet emission in the low-energy regime is significantly suppressed when the emission region of the jet is just encircled by a hot cocoon. Correspondingly, there is a sharp decay in the light curves of the jet emission in the low-energy regime, which can be understood to signify strong TeV emission in GRBs. Since the radius of the cocoon expands with the observer time t obs, the suppression of the jet emission in the low-energy regime may be relieved and thus the light curves of the jet emission would return to those of emission without a cocoon-external inverse-Compton cooling effect. For a long-lasting jet with power ∝ (1 + t obs / t c) α , an internal plateau followed by a sharp decay may generally appear. [ABSTRACT FROM AUTHOR]
- Subjects :
- *PHOTON emission
*GAMMA ray bursts
*COCOONS
*LIGHT curves
*COOLDOWN
Subjects
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 960
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 174324907
- Full Text :
- https://doi.org/10.3847/1538-4357/ad08bc