Nonradial oscillations of neutron stars: A new branch of strongly damped normal modes

1993 ◽  
Vol 48 (8) ◽  
pp. 3467-3472 ◽  
Author(s):  
M. Leins ◽  
H. -P. Nollert ◽  
M. H. Soffel
Keyword(s):  
Neutron Stars ◽  
Normal Modes ◽  
Strongly Damped ◽  
Nonradial Oscillations

Nonradial oscillations of neutron stars and emitted gravitational waves: Computing strongly damped normal modes

2017 ◽  
Vol 28 (06) ◽  
pp. 1750080
Author(s):  
V. S. Geroyannis ◽  
E. E. Tzelati ◽  
V. G. Karageorgopoulos
Keyword(s):  
Differential Equations ◽  
Complex Plane ◽  
Normal Modes ◽  
Line Contour ◽  
Polytropic Model ◽  
Common Reference ◽  
Straight Line ◽  
Final Integration ◽  
Strongly Damped ◽  
Nonradial Oscillations

In this paper, we compute eigenfrequencies of strongly damped normal modes arising from the coupling of the nonradial oscillations of a neutron star to the oscillations of the space-time metric, so-called “w-modes”, by integrating all involved differential equations in the complex plane. Regarding the interior of the star, we use the so-called “complex-plane strategy”. Specifically, we integrate the differential equations of the nonradial fluid oscillations of a general-relativistic polytropic model, simulating the star, along a straight-line contour placed parallel to the real axis and at small imaginary distance from it, thus avoiding a singularity at the stellar center. Regarding the exterior of the star, we use a method proposed by Andersson, Kokkotas and Schutz, following a slightly different terminating procedure. Specifically, (i) we integrate the equations along a straight-line contour lying parallel to the so-called “anti-Stokes lines”, on which the exponential divergence of the solution is drastically suppressed, so that the outgoing and ingoing waves become comparable; and (ii) we carry out one final integration up to a “common reference point”, thus comparing all results at this point. We verify the reliability and accuracy of the method by comparing our numerical results to corresponding ones appearing in the bibliography.

scholarly journals Ultra-long-lived quasi-normal modes of neutron stars in massive scalar-tensor gravity

2020 ◽  
Vol 130 (5) ◽  
pp. 50002 ◽  
Author(s):  
Jose Luis Blázquez-Salcedo ◽  
Fech Scen Khoo ◽  
Jutta Kunz
Keyword(s):  
Neutron Stars ◽  
Normal Modes ◽  
Massive Scalar

Rapidly rotating relativistic stars

1992 ◽  
Vol 340 (1658) ◽  
pp. 391-422 ◽  
Keyword(s):  
Neutron Stars ◽  
Numerical Models ◽  
Normal Modes ◽  
Rotating Stars ◽  
Relativistic Stars ◽  
Small Oscillations ◽  
Perfect Fluids ◽  
Upper Limits ◽  
Viscosity Limit

Within the last decade, significant progress has been made in modelling rotating stars in general relativity and in relating observable properties to the equation of state of matter at high density. A formalism describing rotating perfect fluids is presented and numerical models of neutron stars are briefly discussed, with emphasis on upper limits on mass and rotation. The equations governing small oscillations are reviewed, and a variational principle appropriate both to eulerian and lagrangian perturbations is obtained. This extends to relativity an eulerian principle used to find non-axisymmetric stability points for perfect fluids. A related eulerian approach has been recently used to obtain normal modes of rotating newtonian stars. The review concludes with an outline of this work and of the two types of instability that can restrict the range of neutron stars. In particular, current work shows that several kinds of effective viscosity limit the possible role of a non-axisymmetric instability driven by gravitational waves.

Nonradial oscillations of neutron stars

1988 ◽  
Vol 325 ◽  
pp. 725 ◽  
Author(s):  
P. N. McDermott ◽  
H. M. van Horn ◽  
C. J. Hansen
Keyword(s):  
Neutron Stars ◽  
Nonradial Oscillations

The shear modulus of the neutron star crust and nonradial oscillations of neutron stars

1991 ◽  
Vol 375 ◽  
pp. 679 ◽  
Author(s):  
T. Strohmayer ◽  
H. M. van Horn ◽  
S. Ogata ◽  
H. Iyetomi ◽  
S. Ichimaru
Keyword(s):  
Neutron Star ◽  
Shear Modulus ◽  
Neutron Stars ◽  
Neutron Star Crust ◽  
Nonradial Oscillations
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