Axion-like Particles from Hypernovae

TL;DR

This paper investigates how ultra-strong magnetic fields in hypernovae cores can produce axion-like particles (ALPs) via photon conversion, significantly enhancing their emission and offering new detection prospects through gamma-ray observations.

Contribution

It demonstrates that magnetic fields in hypernovae cores can greatly increase ALP production, especially for masses around 10 MeV, revealing a novel mechanism and detection pathway.

Findings

ALP emissivity is over 100 times larger than previous estimates.

Massive ALPs cause delayed gamma-ray signals from decay.

High-statistics gamma-ray satellites can probe this ALP production mechanism.

Abstract

It was recently pointed out that very energetic subclasses of supernovae (SNe), like hypernovae and superluminous SNe, might host ultra-strong magnetic fields in their core. Such fields may catalyze the production of feebly interacting particles, changing the predicted emission rates. Here we consider the case of axion-like particles (ALPs) and show that the predicted large scale magnetic fields in the core contribute significantly to the ALP production, via a coherent conversion of thermal photons. Using recent state-of-the-art SN simulations including magnetohydrodynamics, we find that if ALPs have masses $m_a \sim {\mathcal O}(10)\, \rm MeV$, their emissivity via magnetic conversions is over two orders of magnitude larger than previously estimated. Moreover, the radiative decay of these massive ALPs would lead to a peculiar delay in the arrival times of the daughter photons. Therefore, high-statistics gamma-ray satellites can potentially discover MeV ALPs in an unprobed region of the parameter space and shed light on the magnetohydrodinamical nature of the SN explosion.