GRB 080319B: A Naked-Eye Stellar Blast from the Distant Universe

TL;DR

GRB 080319B was an exceptionally bright gamma-ray burst with naked-eye visibility, providing detailed insights into the physics of relativistic jets and the environment of massive star explosions.

Contribution

This paper presents detailed optical and gamma-ray observations of GRB 080319B, revealing the origin of emissions and jet structure in a long gamma-ray burst from a massive star.

Findings

Optical and gamma-ray emissions originate from different spectral components in the same region.

The burst involved an extremely relativistic outflow.

The afterglow's chromatic behavior supports a two-component jet model.

Abstract

Long duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse of a massive star. Over the last forty years, our understanding of the GRB phenomenon has progressed dramatically; nevertheless, fortuitous circumstances occasionally arise that provide access to a regime not yet probed. GRB 080319B presented such an opportunity, with extraordinarily bright prompt optical emission that peaked at a visual magnitude of 5.3, making it briefly visible with the naked eye. It was captured in exquisite detail by wide-field telescopes, imaging the burst location from before the time of the explosion. The combination of these unique optical data with simultaneous gamma-ray observations provides powerful diagnostics of the detailed physics of this explosion within seconds of its formation. Here we show that the prompt optical and gamma-ray emissions from this event likely arise from different spectral components within the same physical region located at a large distance from the source, implying an extremely relativistic outflow. The chromatic behaviour of the broadband afterglow is consistent with viewing the GRB down the very narrow inner core of a two-component jet that is expanding into a wind-like environment consistent with the massive star origin of long GRBs. These circumstances can explain the extreme properties of this GRB.