We present results about the effect of the use of a stiffer equation of state, namely the ideal-fluid Γ=2.75 one, on the dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full general relativity. We determine the change on the critical value of the instability parameter β for the emergence of the instability when the adiabatic index Γ is changed from 2 to 2.75 in order to mimic the behavior of a realistic equation of state. In particular, we show that the threshold for the onset of the bar-mode instability is reduced by this change in the stiffness and give a precise quantification of the change in value of the critical parameter βc. We also extend the analysis to lower values of β and show that low-beta shear instabilities are present also in the case of matter described by a simple polytropic equation of state.

Neutron star instabilities in full general relativity using a Γ=2.75 ideal fluid / DE PIETRI, Roberto; Feo, Alessandra; Franci, Luca; Frank, Löffler. - In: PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY. - ISSN 1550-7998. - 90:2(2014), pp. 024034-1-024034-15. [10.1103/PhysRevD.90.024034]

Neutron star instabilities in full general relativity using a Γ=2.75 ideal fluid

DE PIETRI, Roberto;FEO, Alessandra;FRANCI, Luca;
2014-01-01

Abstract

We present results about the effect of the use of a stiffer equation of state, namely the ideal-fluid Γ=2.75 one, on the dynamical bar-mode instability in rapidly rotating polytropic models of neutron stars in full general relativity. We determine the change on the critical value of the instability parameter β for the emergence of the instability when the adiabatic index Γ is changed from 2 to 2.75 in order to mimic the behavior of a realistic equation of state. In particular, we show that the threshold for the onset of the bar-mode instability is reduced by this change in the stiffness and give a precise quantification of the change in value of the critical parameter βc. We also extend the analysis to lower values of β and show that low-beta shear instabilities are present also in the case of matter described by a simple polytropic equation of state.
2014
Neutron star instabilities in full general relativity using a Γ=2.75 ideal fluid / DE PIETRI, Roberto; Feo, Alessandra; Franci, Luca; Frank, Löffler. - In: PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY. - ISSN 1550-7998. - 90:2(2014), pp. 024034-1-024034-15. [10.1103/PhysRevD.90.024034]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2747957
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