Lensed fast radio bursts as a probe of time-varying gravitational potential induced by wave dark matter

TL;DR

This paper proposes using lensed fast radio bursts to detect time-varying gravitational potentials caused by wave dark matter, offering a new way to test the wave nature of dark matter halos through precise timing measurements.

Contribution

It introduces a novel method to probe wave dark matter by analyzing the temporal variations in gravitational potential via lensed FRBs.

Findings

Time-varying potential can cause measurable signal stretching or compression.

Simulations show effects for $10^{11}M_{\u03a9}$ halos with $10^{-22}$ eV bosons.

Potential to validate wave dark matter nature with upcoming FRB observations.

Abstract

Ultralight bosonic wave dark matter (DM) is preponderantly contesting the conventional cold DM paradigm in predicting diverse and rich phenomena on small scales. For a DM halo made of ultralight bosons, the wave interference naturally induces slow de Broglie time-scale fluctuations of the gravitational potential. In this paper, we first derive an estimation for the effect of a time-varying gravitational potential on photon propagation. Our numerical simulations suggest that the time-varying potential of a $10^{11}M_{\odot}$ halo composed of $10^{-22}\,\mathrm{eV}$ bosons would stretch or compress a time series signal by a factor of $10^{-10}$. Here, we propose that, due to the precise measurements of their arrival times, lensed repeating fast radio bursts (FRBs) have the potential to effectively validate temporal variations in gravitational potential by monitoring their images over a period of approximately $\mathcal{O}(1)$ years. With rapidly growing FRB observations, this method would serve as a promising method to directly probe the wave nature of galactic DM halos.