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Physics Seminar Date: 28th March, Tuesday Time: 11 am - 12 noon. Venue: Lecture Hall 6 Equations of state in the curved space-time of compact degenerate stars Susobhan Mandal IISER Kolkata. 28-03-23 Abstract In the study of spherical degenerate stars such as neutron stars, general relativistic effects are incorporated by using Tolman-Oppenheimer-Volkoff equations to describe their interior spacetime. However, the equations of states employed in such studies are invariably computed in flat spacetime. We show that the equation of states computed in the curved spacetime of these stars depends explicitly on the metric function. Further, we show that ignoring such metric-dependent gravitational time dilation effect leads one to grossly underestimate the mass limits of these compact stars. We also computed the equation of state for an ensemble of degenerate fermions by using the curved spacetime of a slowly rotating axially symmetric star where we show that the equation of state computed in such curved spacetime depends on the gravitational time dilation as well as on the dragging of inertial frames, unlike an equation of state computed in a globally flat spacetime. The effect of gravitational time dilation leads to a significant enhancement of the maximum mass limit of a degenerate neutron star. However, such an enhancement due to the frame-dragging effect is extremely small. Nevertheless, in general relativity, the frame-dragging effect is crucial for computing the angular momentum of the star which is also shown to be enhanced significantly due to the usage of curved spacetime in computing the equation of state.
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