Spherically symmetric near-critical accretion onto neutron stars

1990 ◽  
Vol 356 ◽  
pp. 572 ◽  
Author(s):  
Guy S. Miller
Keyword(s):  
Neutron Stars ◽  
Spherically Symmetric

scholarly journals Anisotropic Heat Transfer Inside Rotating Neutron Stars

2004 ◽  
Vol 218 ◽  
pp. 39-40
Author(s):  
C. Y. Hui ◽  
K. S. Cheng
Keyword(s):  
Heat Transfer ◽  
Neutron Star ◽  
Simple Model ◽  
Neutron Stars ◽  
Slow Rotation ◽  
Spherically Symmetric ◽  
Transient Energy ◽  
Heat Transport Equation ◽  
Heat Pulses ◽  
Spherically Symmetric Metric

We have developed the anisotropic heat transport equation for rotating neutron stars. With a simple model of neutron star, we also model the propagation of heat pulses resulting from transient energy releases inside the star. Even in the slow rotation limit, the results with rotational effects involved could differ significantly from those obtained with a spherically symmetric metric in the timescale of the thermal afterglow.

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

Symmetry ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 189
Author(s):  
Alexander Balakin ◽  
Alexei Ilin ◽  
Anna Kotanjyan ◽  
Levon Grigoryan
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Equations Of State ◽  
Pressure Profile ◽  
Spherically Symmetric ◽  
Zero Temperature ◽  
New Approach ◽  
Modified Equations

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.

scholarly journals Dynamics of Low Luminosity Accretion onto Neutron Stars: Spherically Symmetric Models

1997 ◽  
Vol 163 ◽  
pp. 824-825
Author(s):  
John C. L. Wang ◽  
Ralph S. Sutherland
Keyword(s):  
Interstellar Medium ◽  
Neutron Stars ◽  
Flow Dynamics ◽  
Stellar Surface ◽  
Spherically Symmetric ◽  
Atomic Processes ◽  
High Luminosity ◽  
Strongly Coupled ◽  
Accretion Flow ◽  
The Galaxy

The ~ 108−109 old neutron stars in the Galaxy may be undergoing low luminosity accretion from the interstellar medium (Ostriker et al. 1970; Shvartsman 1971). It was first recognized by Shvartsman (1971) that the accretion induced radiation from the stellar surface can heat the infalling material, which in turn inhibits further accretion. This preheating instability has been studied in detail in the high luminosity regime where equilibrium ionization and heating holds (e.g., Buff & McCray 1974; Ostriker et al. 1976; Cowie et al. 1978). In the low luminosity regime, however, dynamical timescales are typically much shorter than atomic timescales so the accretion flow dynamics is strongly coupled to non-equilibrium (NEQ) atomic processes (cf. Blaes et al. 1995).

Energy of Gravitational Field of Static Spherically Symmetric Neutron Stars

2003 ◽  
Vol 40 (5) ◽  
pp. 637-640
Author(s):  
Wen De-Hua ◽  
Chen Wei ◽  
Wang Xian-Ju ◽  
Ai Bao-Quan ◽  
Liu Guo-Tao ◽  
...  
Keyword(s):  
Gravitational Field ◽  
Neutron Stars ◽  
Spherically Symmetric

scholarly journals NEUTRON STAR CORES IN THE GENERAL RELATIVISTIC THOMAS-FERMI TREATMENT

2013 ◽  
Vol 23 ◽  
pp. 185-192
Author(s):  
RICCARDO BELVEDERE ◽  
JORGE A. RUEDA ◽  
REMO RUFFINI
Keyword(s):  
General Relativity ◽  
Neutron Stars ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Strong Interactions ◽  
Spherically Symmetric ◽  
The Core ◽  
General Relativistic ◽  
The Mean

We introduce a new set of equations to describe the equilibrium of the core of neutron stars, composed by self-gravitating degenerate neutrons, protons and electrons in β-equilibrium. We take into account strong, weak, electromagnetic and gravitational interactions within the framework of general relativity. We extend the conditions of equilibrium based on the constancy of the Klein potentials to the strongly interactive case. The strong interactions between nucleons are modeled through the exchange of the σ, ω and ρ virtual mesons. The equations are solved numerically in the case of zero temperatures and for a non-rotating spherically symmetric neutron stars in the mean-field approximation.

scholarly journals Superdense Stellar Configurations in the Bimetric Scalar-Tensor Theory of Gravity

2018 ◽  
pp. 327-337
Author(s):  
L. Sh. Grigorian ◽  
H. F. Khachatryan ◽  
A. A. Saharian
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Neutron Stars ◽  
White Dwarfs ◽  
Coupling Parameter ◽  
Spherically Symmetric ◽  
Scalar Tensor Theory ◽  
Metric Tensor ◽  
Tensor Theory ◽  
Theory Of Gravity

Models of static spherically-symmetric stellar configurations are discussed within the framework of the Bimetric scalar-tensor theory of gravity. The latter, in addition to the metric tensor and the scalar field, contains a background metric tensor as an absolute variable of the theory. The simplest variant of the theory with a constant coupling parameter and with a zero cosmological function is considered. The analysis includes both the white dwarfs and neutron stars. It is shown that, depending on the value of the theory parameter, the corresponding masses can be notably larger than those in general relativity.

A model for spherically symmetric accretion onto neutron stars

1989 ◽  
pp. 749-756
Author(s):  
V. Demmel ◽  
G. Morfill ◽  
H. Atmanspacher
Keyword(s):  
Neutron Stars ◽  
Spherically Symmetric

scholarly journals Atmospheric oscillations provide simultaneous measurement of neutron star mass and radius

2019 ◽  
Vol 487 (4) ◽  
pp. 5129-5142 ◽  
Author(s):  
D A Bollimpalli ◽  
M Wielgus ◽  
D Abarca ◽  
W Kluźniak
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Light Curves ◽  
Spherically Symmetric ◽  
X Ray ◽  
Damped Oscillations ◽  
Neutron Star Mass ◽  
Frequency Maximum ◽  
Analytic Derivation ◽  
Oscillation Frequencies

ABSTRACT Neutron stars with near-Eddington observable luminosities were shown to harbour levitating atmospheres, suspended above their surfaces. We report a new method to simultaneously measure the mass and radius of a neutron star based on oscillations of such atmospheres. In this paper, we present an analytic derivation of a family of relativistic, oscillatory, spherically symmetric eigenmodes of the optically and geometrically thin levitating atmospheres, including the damping effects induced by the radiation drag. We discover characteristic maxima in the frequencies of the damped oscillations and show that from a measurement of the frequency maximum and of the luminosity one can determine the mass and radius of the neutron star. In addition to the stellar parameters, observation of the variation of the oscillation frequencies with flux would allow us to estimate the stellar luminosity and therefore the distance to the source with an accuracy of a few per cent. We also show that the ratio of any two undamped eigenfrequencies depends only on the adiabatic index of the atmosphere, while for the damped eigenfrequencies, this ratio varies with the luminosity. The damping coefficient is independent of the mode number of the oscillations. Signatures of the dynamics of such atmospheres will be reflected in the source’s X-ray light curves.

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