Fermionic Dark Matter's Role in Shaping Neutron Star Properties

Recent research has explored the implications of fermionic dark matter interactions on anisotropic neutron stars. The study, titled "Implications of Fermionic Dark Matter Interactions on Anisotropic Neutron Stars," was authored by Premachand Mahapatra, Chiranjeeb Singha, Ayush Hazarika, and Prasanta Kumar Das and is available on arXiv (arXiv:2408.14020).

The research challenges the common assumption that pressure within neutron stars is isotropic, revealing that it is, in fact, locally anisotropic. The authors employed a two-fluid formalism incorporating three different equations of state (EOS): AP3, BSk22, and MPA1. These models allowed them to analyze how the presence of a subfraction of dark matter affects the macroscopic properties of neutron stars, including mass, radius, and tidal deformability.

Key findings indicate that as the dark matter subfraction increases, the anisotropic configurations can still satisfy observational constraints derived from events such as the binary neutron star merger GW170817 and NICER x-ray measurements. The study also notes that increasing the coupling between dark matter and its mediator results in a core-halo structure, with dark matter forming a halo around the baryonic matter.

The authors suggest that binary pulsar systems could provide constraints on the characteristics of these anisotropic neutron stars, potentially offering evidence for the existence of dark matter within them. This work contributes to the ongoing discourse on the nature of dark matter and its effects on astrophysical phenomena, particularly in extreme environments like neutron stars.