Measuring the neutron star equation of state from EMRIs in dark matter environments with LISA

Fuente: arXiv
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Main Authors: Karydas, Theophanes K., Bertone, Gianfranco
Format: Preprint
Published: 2025
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author Karydas, Theophanes K.
Bertone, Gianfranco
author_facet Karydas, Theophanes K.
Bertone, Gianfranco
contents Gravitational-wave observations of extreme mass-ratio inspirals (EMRIs) in vacuum are largely insensitive to the internal structure of the small compact companion. We show that this conclusion can change when the central black hole is surrounded by a dense dark matter environment. We compute, for the first time, the relativistic dynamical-friction force on a neutron star moving through a collisionless medium and its impact on the evolution of EMRIs embedded in dense dark matter spikes. We then perform a Bayesian parameter-estimation analysis of simulated LISA observations to assess the measurability of both spike properties and the companion's internal structure. We find that, in our fiducial dark matter spike models, EMRIs with signal-to-noise ratio (SNR) $\gtrsim 20$ already allow us to distinguish neutron star from black hole companions, while events with SNR $\gtrsim 400$ make it possible to discriminate between different neutron star equations of state.
format Preprint
id arxiv_https___arxiv_org_abs_2512_10855
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measuring the neutron star equation of state from EMRIs in dark matter environments with LISA
Karydas, Theophanes K.
Bertone, Gianfranco
General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
Gravitational-wave observations of extreme mass-ratio inspirals (EMRIs) in vacuum are largely insensitive to the internal structure of the small compact companion. We show that this conclusion can change when the central black hole is surrounded by a dense dark matter environment. We compute, for the first time, the relativistic dynamical-friction force on a neutron star moving through a collisionless medium and its impact on the evolution of EMRIs embedded in dense dark matter spikes. We then perform a Bayesian parameter-estimation analysis of simulated LISA observations to assess the measurability of both spike properties and the companion's internal structure. We find that, in our fiducial dark matter spike models, EMRIs with signal-to-noise ratio (SNR) $\gtrsim 20$ already allow us to distinguish neutron star from black hole companions, while events with SNR $\gtrsim 400$ make it possible to discriminate between different neutron star equations of state.
title Measuring the neutron star equation of state from EMRIs in dark matter environments with LISA
topic General Relativity and Quantum Cosmology
Cosmology and Nongalactic Astrophysics
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2512.10855