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Broadband modeling of the GRB prompt emission from optical to gamma-rays

Presentation #200.02 in the session Multi-Messenger and Time Domain Astronomy.

Published onJul 01, 2023
Broadband modeling of the GRB prompt emission from optical to gamma-rays

Despite more than 5,000 detected Gamma-Ray Bursts (GRBs), the nature of the prompt emission and the physical mechanisms powering the GRB relativistic jets are still strongly debated. During the past decade, several studies showed that the gamma-ray prompt emission spectra are more complex than the smoothly broken power law traditionally used (i.e., the Band function). New models emerged, and among them, the three-component model that we propose provides an excellent description of the broadband time-resolved prompt emission of both short and long GRBs from optical to high-energy gamma rays: (i) a quasi-thermal component compatible with emission from the jet photosphere; (ii) a non-thermal component compatible with synchrotron radiation from accelerated electrons within the jet; and (iii) a second non-thermal component, which may be related to magnetic reconnections downstream the jet. Moreover, this model enables a new luminosity/hardness relation suggesting that GRBs may be standard candles; this relation may reveal the underlying physics behind the famous Amati, Ghirlanda, and Yonetoku relations. I will present this three-component model using particularly bright GRBs detected with Fermi, CGRO/BATSE, Swift+Suzaku/WAM, and Wind/Konus, including the two most luminous ones, GRB 130427B and GRB 221009A, also nicknamed the B.O.A.T (Brightest Of All Time). I will discuss the striking similarities of all GRBs using this model and the possible universality of the derived luminosity/hardness relation.

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