Relativistic Neutron Stars: Rheological Type Extensions of the Equations of State

Symmetry

Alexei Ilin¹  Alexander Balakin¹  Levon Grigoryan²  Anna Kotanjyan³ 

[1] Department of General Relativity and Gravitation, Institute of Physics, Kazan Federal University, Kremlevskaya str. 18, 420008 Kazan, Russia;Institute of Applied Problems in Physics NAS RA, 25 Nersessian Street, Yerevan 0014, Armenia;Laboratory of Theoretical Physics of Scientific Research Institute of Physics: Faculty of Physics, Yerevan State University, 1 Alex Manoogian, Yerevan 0025, Armenia;

关键词: modified gravity;    neutron star;    equation of state;   

DOI  :  10.3390/sym11020189

来源: DOAJ

【 摘 要 】

Based on the Rheological Paradigm, we extend the equations of state for relativistic spherically symmetric static neutron stars, taking into consideration the derivative of the matter pressure along the so-called director four-vector. The modified equations of state are applied to the model of a zero-temperature neutron condensate. This model includes one new parameter with the dimensionality of length, which describes the rheological type screening inside the neutron star. As an illustration of the new approach, we consider the rheological type generalization of the non-relativistic Lane⁻Emden theory and find numerically the profiles of the pressure for a number of values of the new guiding parameter. We have found that the rheological type self-interaction makes the neutron star more compact, since the radius of the star, related to the first null of the pressure profile, decreases when the modulus of the rheological type guiding parameter grows.

【 授权许可】

Unknown