Multimessenger signals from compact axion star mergers

TY - JOUR

T1 - Multimessenger signals from compact axion star mergers

AU - Chung-Jukko, Liina

AU - Lim, Eugene A.

AU - Marsh, David J. E.

PY - 2024/9/3

Y1 - 2024/9/3

N2 - Axion dark matter can form stable, self-gravitating, and coherent configurations known as axion stars, which are rendered unstable above a critical mass by the Chern-Simons coupling to electromagnetism. We study, using numerical relativity, the merger and subsequent decay of compact axion stars. We show that two subcritical stars can merge, and form a more massive, excited, and critical star, which survives for a finite period before rapidly decaying via electromagnetic radiation. We find a rich multimessenger signal, composed of gravitational waves, electromagnetic radiation, and axion radiation. The gravitational wave signal is broken into two parts: a weak and broad signal from the merger, followed by a much stronger signal of almost fixed frequency from the decay. The electromagnetic radiation follows only the gravitational waves from the decay, while the axion signal is continuous throughout the process. We briefly discuss the detectability of such a signal.

AB - Axion dark matter can form stable, self-gravitating, and coherent configurations known as axion stars, which are rendered unstable above a critical mass by the Chern-Simons coupling to electromagnetism. We study, using numerical relativity, the merger and subsequent decay of compact axion stars. We show that two subcritical stars can merge, and form a more massive, excited, and critical star, which survives for a finite period before rapidly decaying via electromagnetic radiation. We find a rich multimessenger signal, composed of gravitational waves, electromagnetic radiation, and axion radiation. The gravitational wave signal is broken into two parts: a weak and broad signal from the merger, followed by a much stronger signal of almost fixed frequency from the decay. The electromagnetic radiation follows only the gravitational waves from the decay, while the axion signal is continuous throughout the process. We briefly discuss the detectability of such a signal.

U2 - 10.1103/PhysRevD.110.063506

DO - 10.1103/PhysRevD.110.063506

M3 - Article

SN - 2470-0029

VL - 110

JO - Physical Review D

JF - Physical Review D

IS - 6

M1 - 063506

ER -