# Accretion-Induced Collapse of Dark Matter Admixed White Dwarfs -- II: Rotation and Gravitational-wave Signals

## TL;DR

This paper uses hydrodynamical simulations to study how dark matter influences the collapse of rotating white dwarfs and their gravitational-wave signals, revealing potential for dark matter detection through gravitational waves.

## Contribution

It introduces the first detailed analysis of dark matter's impact on accretion-induced collapse and gravitational-wave signals from rotating white dwarfs.

## Key findings

- Dark matter delays collapse and reduces proto-neutron star mass.
- Gravitational-wave amplitude ratios can infer dark matter mass and rotation parameters.
- Dark matter cores >0.03 solar masses can be detected via gravitational waves.

## Abstract

We present axisymmetric hydrodynamical simulations of accretion-induced collapse (AIC) of dark matter (DM) admixed rotating white dwarfs (WD) and their burst gravitational-wave (GW) signals. For initial WD models with the same central baryon density, the admixed DM is found to delay the plunge and bounce phases of AIC, and decrease the central density and mass of the proto-neutron star (PNS) produced. The bounce time, central density and PNS mass generally depend on two parameters, the admixed DM mass $M_\mathrm{DM}$ and the ratio between the rotational kinetic and gravitational energies of the inner core at bounce $\beta_\mathrm{ic,b}$. The emitted GWs have generic waveform shapes and the variation of their amplitudes $h_+$ show a degeneracy on $\beta_\mathrm{ic,b}$ and $M_\mathrm{DM}$. We found that the ratios between the GW amplitude peaks around bounce allow breaking the degeneracy and extraction of both $\beta_\mathrm{ic,b}$ and $M_\mathrm{DM}$. Even within the uncertainties of nuclear matter equation of state, a DM core can be inferred if its mass is greater than 0.03 $M_{\odot}$. We also discuss possible DM effects on the GW signals emitted by PNS g-mode oscillations. GW may boost the possibility for the detection of AIC, as well as open a new window in the indirect detection of DM.