| Title: |
GRB 230204B: GIT Discovery of a Fast Fading Afterglow Associated with an Energetic Gamma-Ray Burst from a Massive Star Progenitor |
| Authors: |
Swain, Vishwajeet; Bhalerao, Varun; Kumar, Harsh; Goyal, Mehul; Ghosh, Ankur; Pathak, Utkarsh; Chandra, Poonam; Ahumada, Tomás; Anupama, G. C.; Bala, S.; Barway, Sudhanshu; Bloom, Joshua S.; Dimple; Karambelkar, Viraj; Kasliwal, Mansi; Misra, Kuntal; Purdum, Josiah; Saraogi, Divita; Sollerman, Jesper; Suresh, Aswin; van der Walt, Stéfan; Waratkar, Gaurav |
| Source: |
Astrophysical Journal, 1000(1), 58, (2026-03-20) |
| Publisher Information: |
American Astronomical Society |
| Publication Year: |
2026 |
| Collection: |
Caltech Authors (California Institute of Technology) |
| Subject Terms: |
Gamma-ray bursts; Wolf-Rayet stars; Relativistic jets |
| Description: |
We present a comprehensive multiwavelength study of a bright gamma-ray burst GRB 230204B, analyzing both prompt and afterglow emissions. This GRB is highly energetic, with an isotropic equivalent energy emission of E iso ∼ 2.2 × 10 54 erg released during the prompt emission. The GROWTH-India Telescope discovered a bright afterglow ( m r = 15.55) that fades rapidly (∝ t −1.82 ). The prompt emission shows a strong thermal photospheric emission along with a nonthermal high-energy component. We explore the evolution of these components and find them to be consistent with the theoretical expectations of the fireball model. Afterglow modeling reveals an energetic jet ( E γ ≳ 10 52 erg) expanding into a wind-type medium viewed nearly on-axis, suggesting a massive star progenitor with strong winds. We also explore correlations between the prompt emission and afterglow that may help to place GRB 230204B within the broader context of the long GRB population. ; © 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence . Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. ; We thank the anonymous referee for the comments and suggestions that have helped us to improve the paper. We thank all the people from the GROWTH collaboration for the observation. GIT (H. Kumar et al. 2022 ) is a 70 cm telescope with a 07 field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/ . The National Radio Astronomy Observatory and Green Bank Observatory are ... |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
https://arxiv.org/abs/arXiv:2512.03136; https://authors.library.caltech.edu/communities/caltechauthors/ |
| DOI: |
10.3847/1538-4357/ae459f |
| Availability: |
https://doi.org/10.3847/1538-4357/ae459f |
| Rights: |
info:eu-repo/semantics/openAccess ; Creative Commons Attribution 4.0 International ; https://creativecommons.org/licenses/by/4.0/legalcode |
| Accession Number: |
edsbas.DD7C55E |
| Database: |
BASE |