Axions from Neutron Star Mergers

TL;DR

This paper investigates the potential production of axion-like particles in neutron star mergers and assesses their detectability via gamma-ray signals, offering new insights into particle physics and astrophysics.

Contribution

It provides the first estimate of ALP production in neutron star mergers and evaluates their potential gamma-ray signals detectable by Fermi-LAT.

Findings

ALPs can produce detectable gamma-ray signals from neutron star mergers.

Detection of such signals could reveal properties of ALPs and neutron star merger physics.

Neutron star mergers are promising sources for ALP searches with current gamma-ray telescopes.

Abstract

Axion-like particles (ALP) can in principle be produced in very hot and dense astrophysical environments, escape from the extreme object where such conditions are met, and then be converted in gamma--rays in the magnetic fields intervening between the event and the Earth. This process potentially offers a new window on both the physics of the axions, and the inner working of the astrophysical objects where they are produced. Interestingly, while this process has been studied for core--collapse supernovae and other extreme astrophysical events, no estimate exists for Neutron Star Mergers, objects recently identified through the detection of gravitational waves. In this work we study the production of ALPs in neutron star mergers, finding that for a large region of the ALP parameter space its magnitude at the source is such to produce a sizable gamma-ray signal at Earth. We show detection forecasts for such events placed in nearby galaxies, finding that they are potentially observable with the Fermi--LAT, thus opening a new window into both the astrophysics of these cataclysmic events, and of new particles beyond the standard model.