Searching for Ultralight Dark Matter Solitons with Gravitational Waves

Abstract: Ultralight Dark Matter (ULDM) offers an alternative to cold dark matter, characterized by wavelike behavior on galactic scales. This contribution summarizes our work~\cite{Blas:2024duy} on how solitonic cores induced by ULDM affect gravitational waves (GWs), enabling their detection through next-generation observatories like LISA, Einstein Telescope and Cosmic Explorer. We show that continuous GWs from spinning neutron stars near the Galactic Center (GC) can probe solitons for (m \lesssim 10^{-22}\, \mathrm{eV}) and surpass current constraints on the ULDM couplings to the Standard Model for masses (m \lesssim 10^{-20}\, \mathrm{eV}). Additionally, GW modulation could reveal solitons in extragalactic systems, particularly in more massive halos, highlighting the broad potential of GW-based methods for uncovering ULDM properties.