Abstract Details

Name: KRISHNAPRAKASH NUNNA
Affiliation: BITS-PILANI HYDERABAD CAMPUS
Conference ID: ASI2020_405
Title : Stability analysis of a differentially rotating, hot, hypermassive Neutron Star merger remnant
Authors and Co-Authors : SARMISTHA BANIK,DEBARATI CHATTERJEE ,KRISHNAPRAKASH NUNNA
Abstract Type : Oral
Abstract Category : Stars, ISM and Galaxy
Abstract : The stability of the merger remnant depends crucially on the underlying Equation of State (EoS) as well as the differential rotation velocity profile of the Neutron Stars(NS). Thus it provides a method to probe the nature of dense matter in NS cores, which is still a mystery, as the nature of dense matter beyond saturation density is not accessible to terrestrial experiments. The recent detection of NS merger event GW170817 has opened up a new window to the universe. Post-merger searches by the LIGO-VIRGO collaboration did not find evidence for Gravitational Radiation(GW) from the remnant. One probable outcome is a differentially rotating hot hypermassive neutron star. We consider the most realistic solutions of differentially rotating class "A" stars, which always have a mass-shedding limit. For this we consider zero-temperature as well as finite entropy EoSs based on the phenomenological Relativistic Mean Field (RMF) with density-dependent coefficients. We constructed relativistic equilibrium sequences of differentially rotating NSs and calculate the extra mass supported by the rotating star compared to the static star. We also generate equilibrium sequences with different degrees of differential rotation. For constant angular momentum sequences the onset of the secular instability is then marked by the ”Turning point” criterion i.e. the maximum of the gravitational masses as a function of central density. We also investigate whether the presence of strangeness affects the universality relations and find the existence of two families of curves of hot and cold stars for a differentially rotating star. We examine the universality with a range of differential rotation parameters as well. Finally we compute the collapse time of the NS merger remnant for the different EoSs and compared them with the window allowed by observations of progenitor mass from short gamma ray bursts and GW170817.