Anisotropic Neutron Stars Modelling: Constraints in Krori-Barua Spacetime. (arXiv:2007.09797v1 [gr-qc])
<a href="http://arxiv.org/find/gr-qc/1/au:+Roupas_Z/0/1/0/all/0/1">Zacharias Roupas</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Nashed_G/0/1/0/all/0/1">Gamal G. L. Nashed</a>
Dense nuclear matter is expected to be anisotropic due to effects such as
solidification, superfluidity, strong magnetic fields, hyperons,
pion-condesation. Therefore an anisotropic pulsars core seems more realistic
than an ideally isotropic one. We model anisotropic neutron stars working in
the Krori-Barua (KB) ansatz without preassuming an equation of state. We show
that the physics of general KB solutions is encapsulated in the compactness.
Imposing physical and stability requirements yields a maximum allowed
compactness $2GM/Rc^2 < 0.71$ for a KB-spacetime. We further input
observational data from numerous pulsars and calculate the boundary density. We
focus especially on data from the LIGO/Virgo collaboration as well as recent
independent measurements of mass and radius of miilisecond pulsars with white
dwarf companions by the textit{Neutron Star Interior Composition Explorer}
(NICER). For these data the KB-spacetime gives the same boundary density which
surprisingly equals the nuclear saturation density within the data precision.
Since this value designates the boundary of a neutron core, the KB-spacetime
applies naturally to pulsars. For this boundary condition we calculate a
maximum mass of 4.1 solar masses.
Dense nuclear matter is expected to be anisotropic due to effects such as
solidification, superfluidity, strong magnetic fields, hyperons,
pion-condesation. Therefore an anisotropic pulsars core seems more realistic
than an ideally isotropic one. We model anisotropic neutron stars working in
the Krori-Barua (KB) ansatz without preassuming an equation of state. We show
that the physics of general KB solutions is encapsulated in the compactness.
Imposing physical and stability requirements yields a maximum allowed
compactness $2GM/Rc^2 < 0.71$ for a KB-spacetime. We further input
observational data from numerous pulsars and calculate the boundary density. We
focus especially on data from the LIGO/Virgo collaboration as well as recent
independent measurements of mass and radius of miilisecond pulsars with white
dwarf companions by the textit{Neutron Star Interior Composition Explorer}
(NICER). For these data the KB-spacetime gives the same boundary density which
surprisingly equals the nuclear saturation density within the data precision.
Since this value designates the boundary of a neutron core, the KB-spacetime
applies naturally to pulsars. For this boundary condition we calculate a
maximum mass of 4.1 solar masses.
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