GRB 230204B: GIT Discovery of a Fast Fading Afterglow Associated with an Energetic GRB from a Massive-Star Progenitor

2025/12/02 by Swain, Vishwajeet, Bhalerao, Varun, Kumar, Harsh +19
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE)

paper · doi:10.48550/arxiv.2512.03136

Abstract

We present a comprehensive multi-wavelength 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 E_iso ∼ 2.2 × 10⁵⁴ erg, released during the prompt emission. The GROWTH-India Telescope discovered a bright afterglow (m_r = 15.55) that faded rapidly (∝ t^-1.82). The prompt emission shows strong thermal photospheric emission, along with a non-thermal high-energy component. We explore the evolution of these components and find them to be consistent with theoretical expectations. Afterglow modeling reveals an energetic jet E_tot \gtrsim 10⁵² 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 understand the complete picture of GRB progenitors.

Citations

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