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GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann

Kann, D. A., Agayeva, S., Aivazyan, V., Alishov, S., Andrade, C. M., Antier, S., Baransky, A., Bendjoya, P., Benkhaldoun, Z., Beradze, S., and others. (2023) GRANDMA and HXMT Observations of GRB 221009A: The Standard Luminosity Afterglow of a Hyperluminous Gamma-Ray Burst—In Gedenken an David Alexander Kann. The Astrophysical Journal Letters, 948 (2). Article Number L12. ISSN 2041-8213. (doi:10.3847/2041-8213/acc8d0) (KAR id:101213)

Abstract

Object GRB 221009A is the brightest gamma-ray burst (GRB) detected in more than 50 yr of study. In this paper, we present observations in the X-ray and optical domains obtained by the GRANDMA Collaboration and the Insight Collaboration. We study the optical afterglow with empirical fitting using the GRANDMA+HXMT-LE data sets augmented with data from the literature up to 60 days. We then model numerically using a Bayesian approach, and we find that the GRB afterglow, extinguished by a large dust column, is most likely behind a combination of a large Milky Way dust column and moderate low-metallicity dust in the host galaxy. Using the GRANDMA+HXMT-LE+XRT data set, we find that the simplest model, where the observed afterglow is produced by synchrotron radiation at the forward external shock during the deceleration of a top-hat relativistic jet by a uniform medium, fits the multiwavelength observations only moderately well, with a tension between the observed temporal and spectral evolution. This tension is confirmed when using the augmented data set. We find that the consideration of a jet structure (Gaussian or power law), the inclusion of synchrotron self-Compton emission, or the presence of an underlying supernova do not improve the predictions. Placed in the global context of GRB optical afterglows, we find that the afterglow of GRB 221009A is luminous but not extraordinarily so, highlighting that some aspects of this GRB do not deviate from the global known sample despite its extreme energetics and the peculiar afterglow evolution.

Item Type: Article
DOI/Identification number: 10.3847/2041-8213/acc8d0
Uncontrolled keywords: 330, High-Energy Phenomena and Fundamental Physics
Subjects: Q Science
Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
Funders: University of Kent (https://ror.org/00xkeyj56)
SWORD Depositor: JISC Publications Router
Depositing User: JISC Publications Router
Date Deposited: 10 May 2023 14:08 UTC
Last Modified: 10 May 2023 14:54 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/101213 (The current URI for this page, for reference purposes)

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