In-depth analysis of ADM accumulation mechanisms in neutron stars

Develop a comprehensive and quantitative analysis of the mechanisms by which asymmetric dark matter (ADM) accumulates in neutron stars and incorporate these results into neutron-star equation-of-state inference frameworks to physically constrain the ADM mass-fraction Fχ and assess the impact of ADM halos on combined baryonic and ADM equations of state.

Background

This paper performs Bayesian parameter estimation using NICER mass–radius measurements and synthetic data to infer constraints on neutron star equations of state (EoS) that may include fermionic asymmetric dark matter (ADM) cores. The analysis adopts a two-fluid TOV formalism, varies both baryonic and ADM EoS parameters, and assigns zero likelihood to ADM halo configurations because halos modify the X-ray pulse profile modeling used by NICER.

In the conclusions, the authors note that current and near-future mass–radius constraints cannot individually pin down key ADM parameters. They explicitly state that a rigorous, in-depth study of ADM accumulation mechanisms in neutron stars is still lacking and leave this for future work. They further indicate that appropriately accounting for ADM halos and physically constraining the ADM mass-fraction Fχ would enable more general and robust constraints on the ADM EoS.

References

While many works consider a variety of different plausible ADM mass-fractions [see e.g., 47–49, 51, 54, 58, 61, 96, 117, and references therein], an in-depth analysis on the possible accumulation methods of ADM in neutron stars has yet to be done and is left for future work. By appropriately accounting for the possible presence of ADM halos and physically constraining Fχ, full inferences on the neutron star EoS will be able to determine the most general constraints on the ADM EoS.

— Probing fermionic asymmetric dark matter cores using global neutron star properties (2410.00140 - Rutherford et al., 30 Sep 2024) in Section V (Summary and Conclusions)