Darksuite: an Algorithm for Dark Matter-Admixed Neutron Stars

Abstract: Gravitational-wave observations provide a unique window into the fundamental nature of massive objects. In particular, neutron star equations of state have been constrained due to the success of gravitational wave observatories. Recently, the possibility of detecting dark matter-admixed neutron stars via ground-based laser interferometry has been explored. Dark matter would impact the gravitational waveform of an inspiraling neutron star system through tidal parameters, namely the tidal deformability ($\lambda$, incurring a phase shift to the frequency evolution of the signal. This phase shift would depend both on the percentage of dark matter within the star and its particle nature, e.g., bosonic or fermionic. Indirect detection of dark matter through admixture within neutron stars can provide insight into the neutron equation of state, as well as constraints on the density of dark matter in the universe. In this work, we introduce \texttt{Darksuite}, a proposed extension of the \lal{} software framework, designed to model the gravitational wave signatures of dark-matter-admixed neutron stars. This framework employs simulations from the two-fluid, generally relativistic Tolman-Oppenheimer-Volkoff equations, wherein one fluid is ordinary nuclear matter and the other is dark matter. We demonstrate interpolation of values from a bank of simulations, enabling the study of binary systems where at least one component may be a dark-matter-admixed neutron star. By leveraging existing methodologies within \lal{} for tidal phase corrections and supplementing them with dark matter effects, \texttt{Darksuite} provides a means to generate and analyze gravitational waveforms for these exotic systems.