Research Projects

The objective of proposed research proposal is to study the properties of compact astrophysical objects known as neutron stars in the presence of ∆ resonance baryons using chiral SU(3) quark mean field model. Due to recent observations of neutron stars with mass above two times solar masses and tight constraints from gravitational wave event GW170817 on mass-radius and tidal deformability and also from NICER data (on mass-radius measurement) as well as future data expected from LIGO-Virgo-KAGRA collaboration in O4 run and LIGO-India project, it is extremely important to understand the properties of compact stars using theoretical approaches considering role of exotic particles and different phases. Our main focus in the study will be to explore the impact of ∆ resonance baryons along with hyperons and nucleons on the EoS and hence, the mass-radius relations, tidal deformability etc. at finite pressure anisotropy and also considering finite magnetic field. When the nuclear/neutron star matter properties are calculated in the presence of magnetic field, the anomalous magnetic moments of baryons play a significant role as they appear in the definitions of scalar and vectors densities. It is important to consider the impact of compact star medium on the modification of magnetic moments of baryons and a self-consistent calculations should be performed to calculate the EoS and structural properties. Although studies are available where anomalous magnetic moments of baryons are calculated in the nuclear matter, however, as per our knowledge, there is only one study (Phys. Rev. C 82, 025804 (2010)) in the literature where medium modification of magnetic moments of baryons were calculated in the medium relevant for neutron stars and further used to calculate the mass-radius relation of these compact stars. It was observed that the medium modification of baryons will cause the stiffness in the EoS and hence, increase in the maximum mass of neutron stars. Further in this study only nucleons and hyperons were considered in the calculations. In our all proposed objectives of the proposal related to finite magnetic field case, we will use medium modified values of magnetic moments of nucleons, hyperons as well as ∆ baryons. The strength of magnetic field in the neutron stars varies from surface to core with range 10¹⁵ to 10¹⁸ G. At magnetic field of strength 10¹⁸ G, the assumption of spherical symmetry may not be true and deformation of stars needs to consider in the calculations. Deformation of stars can act as source of gravitational waves and will impact the structure properties. In the presence of finite pressure anisotropy as well as at strong magnetic field, usual Tolman–Oppenheimer–Volkoff (TOV) equations may not be applicable (spherical symmetry) and therefore, generalized TOV equations will be used in the calculations under various objectives.