Speaker
Description
This work conducts a thorough Bayesian analysis of neutron star matter, incorporating $(\Delta)$-resonances alongside hyperons and nucleons within a density-dependent relativistic hadron (DDRH) model. By leveraging constraints from nuclear saturation properties, chiral effective field theory ($\chi$EFT), NICER radius measurements, and tidal deformability data from GW170817, we systematically examine the role of $(\Delta$)-resonances in shaping the equation of state (EoS) and neutron star observables. Our findings indicate that while $(\Delta)$-baryons soften the EoS at lower densities, they ensure sufficient stiffness at higher densities to sustain neutron stars with masses up to $(2M_{\odot})$. This provides a natural resolution to neutron star radius constraints and aligns well with the observed low-mass compact object in HESS J1731-347 while remaining consistent with GW170817 tidal deformability limits. Furthermore, we find that $(\Delta)$-resonances preferentially populate the outer core of neutron stars, potentially influencing neutron star merger dynamics. Their presence could also play a significant role in neutron star cooling through the direct Urca process. Additionally, we explore quasi-normal $(f)$-mode oscillations within a fully relativistic framework, uncovering strong correlations between the $(f)$-mode frequency, neutron star compactness, and tidal deformability. By incorporating $(\Delta)$-resonances and adhering to astrophysical constraints, we determine $(f_{1.4} = 1.97^{+0.17}_{-0.22})$ KHz and a damping time of $(\tau_{f_{1.4}} = 0.19^{+0.05}_{-0.03})$ s at the $(1\sigma)$ confidence level.
