Inertial modes in stratified rotating neutron stars: An evolutionary description

Journal Article · Fri Apr 15 04:00:00 EDT 2005 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PhysRevD.71.083001· OSTI ID:20709039

Villain, L ^[1]; Bonazzola, S ^[1]; Haensel, P ^[2]

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1. Laboratoire de l'Univers et de ses Theories (UMR 8102 du C.N.R.S.), Observatoire de Paris, Section de Meudon, F-92195 Meudon Cedex (France)
2. Copernicus Astronomical Center (CAMK), Polish Academy of Sciences, Bartycka 18, PL-00-716 Warsaw (Poland)

With (nonbarotropic) equations of state valid even when the neutron, proton, and electron content of neutron star cores is not in beta equilibrium, we study inertial and composition gravity modes of relativistic rotating neutron stars. We solve the relativistic Euler equations in the time domain with a three dimensional numerical code based on spectral methods, in the slow rotation, relativistic Cowling and anelastic approximations. Principally, after a short description of the gravity modes due to smooth composition gradients, we focus our analysis on the question of how the inertial modes are affected by nonbarotropicity of the nuclear matter. In our study, the deviation with respect to barotropicity results from the frozen composition of nonsuperfluid matter composed of neutrons, protons, and electrons, when beta equilibrium is broken by millisecond oscillations. We show that already for moderately fast rotating stars the increasing coupling between polar and axial modes makes those two cases less different than for very slowly rotating stars. In addition, as we directly solve the Euler equations, without coupling only a few number of spherical harmonics, we always find, for the models that we use, a discrete spectrum for the l=m=2 inertial mode. Finally, we conclude that, for nonbarotropic stars, the frequency of this mode, which is our main focus, decreases in a non-negligible way, whereas the time dependence of the energy transfer between polar and axial modes is substantially different due to the existence of low-frequencies gravity modes.

• OSTI ID: 20709039
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 8 Vol. 71; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COSMOLOGY
COUPLING
ELECTRONS
EQUATIONS OF STATE
EQUILIBRIUM
GRAVITATION
NEUTRON STARS
NEUTRONS
NUCLEAR MATTER
OSCILLATIONS
PROTONS
RELATIVISTIC RANGE
ROTATION
SPHERICAL HARMONICS
THREE-DIMENSIONAL CALCULATIONS
TIME DEPENDENCE