A Shock Flash Breaking Out of a Dusty Red Supergiant

TL;DR

This paper reports the earliest multiband observations of a supernova shock breakout from a red supergiant, revealing rapid light curve evolution and dust asymmetry, providing new insights into explosion dynamics.

Contribution

First to capture multiband data of a supernova shock breakout within 1.4 hours, showing rapid evolution and dust asymmetry, advancing understanding of explosion environments.

Findings

Shock breakout observed at 1.4 hours post-explosion

Rapid, faint, and red early light curves inconsistent with simple models

Evidence of non-spherical dust distribution around the supernova

Abstract

Shock breakout emission is light that arises when a shockwave, generated by core-collapse explosion of a massive star, passes through its outer envelope. Hitherto, the earliest detection of such a signal was at several hours after the explosion, though a few others had been reported. The temporal evolution of early light curves should reveal insights into the shock propagation, including explosion asymmetry and environment in the vicinity, but this has been hampered by the lack of multiwavelength observations. Here we report the instant multiband observations of a type II supernova (SN 2023ixf) in the galaxy M101 (at a distance of 6.85+/-0.15 Mpc), beginning at about 1.4 hours after the explosion. The exploding star was a red supergiant with a radius of about 440 solar radii. The light curves evolved rapidly, on timescales of 1-2 hours, and appeared unusually fainter and redder than predicted by models within the first few hours, which we attribute to an optically thick dust shell before it was disrupted by the shockwave. We infer that the breakout and perhaps the distribution of the surrounding dust were not spherically symmetric.