Paper

An axisymmetric shock breakout indicated by prompt polarized emission from the type II supernova 2024ggi

Wheeler, J Craig, Ashall, Chris, Wang, Lifan, Bulla, Mattia, Mishra, Divya, Filippenko, Alexei V, Cikota, Aleksandar, Hoeflich, Peter, Vasylyev, Sergiy S, Wen, Xudong, Li, Gaici, Schulze, Steve, Shengyu Yan, Gal-Yam, Avishay, Gao, He, Patra, Kishore C, Patat, Ferdinando, Baade, Dietrich, Maund, Justyn, Wang, Xiaofeng, Yang, Yi

2025

Overview

The death of massive stars is triggered by an infall-induced bounce shock that disrupts the star. How such a shock is launched and propagates through the star is a decade-long puzzle. Some models assume that the shock can be reenergized by absorbing neutrinos, leading to highly aspherical explosions. Other models involve jet-powered shocks that lead to bipolar explosions reflected in the geometry of the shock-breakout emission. We report measurement of the geometry of the shock breakout through unprecedentedly early spectropolarimetry of the nearby type II supernova 2024ggi starting ~1.2 days after the explosion. The measurement indicates a well-defined symmetry axis of the shock breakout, which is also shared by the hydrogen-rich envelope that emerged after the circumstellar matter was engulfed by the ejecta, revealing a persisting and prominent symmetry axis throughout the explosion. These findings suggest that the physical mechanism driving the explosion of massive stars manifests a well-defined axial symmetry and acts on large scales.

• Publisher: Cornell University Library, arXiv.org
• Subject: Ejecta / Emission / Explosions / Massive stars / Neutrinos / Supernovae / Symmetry