Bridging the Gap: GRB 230812B -- A Three-Second Supernova-Associated Burst Detected by the GRID Mission

TL;DR

This paper reports on GRB 230812B, a bright, 3-second gamma-ray burst associated with a supernova, challenging the traditional classification of short GRBs as solely from compact mergers.

Contribution

It presents evidence that some short-duration GRBs can originate from massive star collapse, expanding the understanding of GRB progenitors.

Findings

GRB 230812B is associated with a supernova, indicating a massive star origin.

The burst's short duration results from engine activity and jet breakout time.

The study challenges the view that all short GRBs are from compact object mergers.

Abstract

GRB 230812B, detected by the Gamma-Ray Integrated Detectors (GRID) constellation mission, is an exceptionally bright gamma-ray burst (GRB) with a duration of only 3 seconds. Sitting near the traditional boundary ($\sim$ 2 s) between long and short GRBs, GRB 230812B is notably associated with a supernova (SN), indicating a massive star progenitor. This makes it a rare example of a short-duration GRB resulting from stellar collapse. Our analysis, using a time-evolving synchrotron model, suggests that the burst has an emission radius of approximately $10^{14.5}$~cm. We propose that the short duration of GRB 230812B is due to the combined effects of the central engine's activity time and the time required for the jet to break through the stellar envelope. Our findings provide another case that challenges the conventional view that short-duration GRBs originate exclusively from compact object mergers, demonstrating that a broader range of durations exists for GRBs arising from the collapse of massive stars.