Speaker
Description
In this work, we explore the impact of higher dimensional spacetime on the stellar structure and thermodynamic properties of neutron stars. Utilizing the density-dependent relativistic hadron field theory, we introduce modifications to incorporate the influence of higher dimensionality. Our methodology involves solving the essential stellar structure equations in the $D$-dimensional spacetime ($D \geq 4$), starting with the modification of the Einstein-Hilbert action, derivation of the Einstein field equation in the $D$-dimension, and application of the resulting exterior Schwarzschild spacetime metric for the $D$-dimension. Our findings indicate that with increasing dimensions, the central density $\rho_{c} G_D$ and the central pressure $p_c G_D$ required to achieve the maximum mass for neutron stars progressively increase, resulting in stiffer neutron matter. Incremental dimensionality also results in a gradual increase in the maximum mass attained, limited to our study between $D=4$ and $D=6$, as no maximum mass value is obtained for $D>6$. We consistently observe the criteria $dM/d\rho_c>0$ fulfilled up to the maximum mass point, supported by stability analysis against infinitesimal radial pulsations. The validity of our solution is confirmed through the causality condition, ensuring that the matter sound speed remains within the speed of light for all cases. Additionally, our examination indicates that the total mass-to-radius ratio for all discussed $D$-dimensional cases comfortably resides within the modified Buchdahl limit. Furthermore, by projecting the compactified $D$-dimensional maximum neutron star mass into the four dimensions, our study suggests that the mass of the secondary object observed in GW190814 can be explained.
