External Inverse-Compton Emission from Low-luminosity Gamma-Ray Bursts: Application to GRB 190829A
Abstract
The detection of TeV gamma-ray bursts (GRBs) brought new opportunities for studying the physics of particle acceleration at relativistic shocks. The High Energy Stereoscopic System (H.E.S.S.) telescopes recently observed very-high-energy (VHE) emission from a nearby low-luminosity GRB, GRB 190829A. Follow-up observations with, e.g., Swift-XRT, revealed unusual flare activities at ~103 s, which can be caused by a long-lasting central engine. We show that the VHE emission during the H.E.S.S. observation time is naturally produced in the external inverse-Compton (EIC) scenario, where seed photons supplied by the flares or other late-time dissipations are upscattered to VHE energies by the nonthermal electrons accelerated at the external forward shock. Our calculations show that the EIC flare nearly coincides with the late-prompt flare, but extends ~3-4 times longer than the duration of the late-prompt flare. The preferred kinetic energy and initial Lorentz factor used in our model are ~1052 erg and ~20, respectively. Understanding the mechanisms of the VHE emission from low-luminosity GRBs will help us constrain the properties of the outflow and the central engine activities, as well as the particle acceleration mechanism.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2021
- DOI:
- 10.3847/1538-4357/ac0cfc
- arXiv:
- arXiv:2012.07796
- Bibcode:
- 2021ApJ...920...55Z
- Keywords:
-
- Stellar jets;
- Gamma-ray bursters;
- X-ray sources;
- Nonthermal radiation sources;
- Radio sources;
- Particle astrophysics;
- 1607;
- 1878;
- 1822;
- 1119;
- 1358;
- 96;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 12 pages, 6 figures, accepted for publication in ApJ. HESS data are added, figures are updated, appendix is extended, main conclusions unchanged