arXiv subjects

Nilaksha Barman

Publications and source records attributed to Nilaksha Barman.

3 recordsLinked to original sources

arXiv2026

Realistic Equations of State Informing Neutron Star Post-Merger Gravitational-Wave Frequencies

Binary neutron star mergers are thought to produce hot, rapidly rotating neutron stars with masses that can far exceed their Tolman-Oppenheimer-Volkoff mass. The gravitational-wave emission from such remnants provides a unique opportunity to measure the nuclear equation of state at densities and temperatures not available to terrestrial experiments. Current detector design is informed by gravitational-wave signals from general relativistic hydrodynamics simulations of neutron star mergers, typically with hybrid thermal treatments for the equation of state, where a cold equation of state is modified by adding a thermal component. We use realistic equations of state based on the relativistic mean field model with consistent treatment of thermal effects to compute the distribution of expected peak gravitational-wave frequencies. Marginalising over equation of state and progenitor neutron star masses, we show the peak frequency of emission ranges from $\sim2.5$ to 4 kHz. The width of this distribution suggests the need for broadband observatories with kHz sensitivity, and calls into question some of the so-called post-merger optimised configurations. We show the proposed KAGRA high-frequency design is well-suited to measuring post-merger remnants when compared to the KAGRA broadband design.

astro-ph.HE↗

arXiv2025

$f$-mode oscillations in hot Neutron Stars: Effect of hyperons and neutrino trapping

In this work, we present an equation of state formalism for hot Neutron Stars (NSs) which consistently includes the effects of finite temperature, hyperons as well as neutrino trapping, relevant for the study of proto-neutron stars, binary neutron star mergers and supernova explosions. Within a non-linear relativistic mean field description, the framework allows for a systematic variation of nuclear parameters within the range allowed by uncertainties in nuclear experimental data, ensuring compatibility with nuclear theory, astrophysical and heavy-ion data. We then investigate the role of nuclear and hypernuclear parameters as well as thermal effects on NS macroscopic properties and $f$-mode oscillations in hot neutron stars within Cowling approximation. Our results reveal that in hyperonic neutron stars with trapped neutrinos, the saturation nuclear density shows moderate to strong correlation with NS astrophysical observables. We also investigate whether thermal effects break universal relations and provide fit relations for hot NS configurations in the neutrino-trapped regime.

astro-ph.HE↗

arXiv2025

Investigating the role of nuclear parameters on oscillation modes in hot Neutron Stars

Recent studies have revealed that certain nuclear parameters are more dominant than others in governing global neutron star properties, such as its structure or oscillation mode characteristics. Although neutron stars can in general assumed to be cold, in astrophysical scenarios such as newly born neutron stars or remnants of binary neutron star mergers, finite temperature effects play a non-negligible role. In this work, we perform a consistent and systematic investigation of the role of nuclear parameters and thermal effects on neutron star properties and fluid oscillation modes within a full general relativistic scheme. We impose constraints on the parameter space of the relativistic mean field model using state-of-the-art information from terrestrial experiments and multi-messenger astrophysical data. We find effective nucleon mass to be the most important nuclear parameter controlling astrophysical observables of hot neutron stars, similar to the cold beta equilibrated matter. However, we conclude that the interplay among saturation properties and astrophysical observables depends not only on the thermal configurations considered but also on the constraints imposed. We also investigated the role of nuclear saturation parameters on some universal relations for hot NSs which are important in gravitational wave asteroseismology. Our investigation confirmed that these relations are mostly insensitive to nuclear saturation properties and mainly affected by variation of charge fraction in the star.

astro-ph.HE↗