scholarly journals General Relativistic Theory of Rotating Neutron Stars – A Review

1971 ◽  
Vol 46 ◽  
pp. 334-340
Author(s):  
Jeffrey M. Cohen
Keyword(s):  
General Relativity ◽  
Neutron Stars ◽  
Relativistic Theory ◽  
White Dwarfs ◽  
Relativistic Effects ◽  
Red Shift ◽  
Light Bending ◽  
Perihelion Advance ◽  
General Relativistic

Except in cosmology, astrophysicists are used to thinking of general relativistic effects as small (e.g., light bending, perihelion advance, red shift) and have generally left such problems to general relativists. However, the discovery of pulsars (Hewish et al., 1968) may have changed this. Not only is general relativity necessary to treat rotating neutron stars, but relativity was also partly responsible for the elimination of pulsating white dwarfs as pulsar models.

scholarly journals Types of Stellar Instabilities

1980 ◽  
Vol 5 ◽  
pp. 433-436
Author(s):  
P. Ledoux
Keyword(s):  
Neutron Stars ◽  
Linear Theory ◽  
White Dwarfs ◽  
Relativistic Effects ◽  
Significant Information ◽  
Average Value ◽  
Eigen Values ◽  
Late Evolution ◽  
General Relativistic ◽  
Formation Phase

Aside from violent phenomena, regular forms of motions originate often in instabilities and the linear theory with terms ∞ exp (st) yields already significant information. The system, here a spherical star, will be the seat of an instability if R (s) > 0. In general, s will be complex as both conservative (adiabatic) and non-conservative (non-adiabatic) factors are present. However if the latter (small) are neglected, the eigen-values s2 often denoted -σ2 are real. If at least one σ2 < 0, then the star is dynamically unstable.Radial perturbations. If an appropriate average value Γ1 > 4/3, then all σ2 are positive. If Γ < 4/3 (formation phase: ionization; late evolution: nuclear equilibrium; degeneracy in white dwarfs and neutron stars or radiation in very large masses plus general relativistic effects) the fundamental eigenvalue of only becomes negative.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

The stellar graveyard

2019 ◽  
pp. 177-206
Author(s):  
Nils Andersson
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Supermassive Black Holes ◽  
Compact Objects ◽  
Fermi Gases ◽  
The 1950S

This chapter introduces the different classes of compact objects—white dwarfs, neutron stars, and black holes—that are relevant for gravitational-wave astronomy. The ideas are placed in the context of developing an understanding of the likely endpoint(s) of stellar evolution. Key ideas like Fermi gases and the Chandrasekhar mass are discussed, as is the emergence of general relativity as a cornerstone of astrophysics in the 1950s. Issues associated with different formation channels for, in particular, black holes are considered. The chapter ends with a discussion of the supermassive black holes that are found at the centre of galaxies.

A NEW EXTENSION OF GENERAL RELATIVISTIC THEORY

1994 ◽  
Vol 03 (02) ◽  
pp. 393-419 ◽  
Author(s):  
MASATOSHI YAZAKI
Keyword(s):  
General Relativity ◽  
General Theory ◽  
Relativistic Theory ◽  
Maxwell's Equations ◽  
Geometrical Structure ◽  
Finsler Geometry ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
General Relativistic ◽  
Einstein’S General Relativity

The possibility of a new extension of the general relativistc theory will be considered using Finsler geometry. The extension of Einstein’s general relativity can be expected to regard gravitational, electroweak, and strong interactive fields as geometrical structure of a spacetime based on Finsler geometry. Indeed, it will be shown that this theory can include the general theory of relativity under a certain special condition. In addition, Maxwell’s equations will be expressed using new metric representations of the electromagnetic vector and its tensor. Moreover, it will be suggested that this theory may include metric representations of weak and strong interactive fields.

TOWARDS A RELATIVISTIC THOMAS-FERMI THEORY OF WHITE DWARFS AND NEUTRON STARS

2011 ◽  
Vol 20 (supp01) ◽  
pp. 141-148
Author(s):  
JORGE A. RUEDA ◽  
REMO RUFFINI
Keyword(s):  
Neutron Stars ◽  
White Dwarfs ◽  
Recent Progress ◽  
Fermi Theory ◽  
Thomas Fermi ◽  
General Relativistic

We summarize recent progress in the formulation of a theory for white dwarfs and neutron stars based on the general relativistic Thomas-Fermi equations of equilibrium.

On claims that general relativity differs from Newtonian physics for self-gravitating dusts in the low velocity, weak field limit

2015 ◽  
Vol 24 (08) ◽  
pp. 1550065 ◽  
Author(s):  
David R. Rowland
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Relativistic Effects ◽  
Weak Field ◽  
Newtonian Gravity ◽  
Galactic Rotation ◽  
Low Velocity ◽  
Rotation Curves ◽  
Newtonian Physics ◽  
General Relativistic

Galaxy rotation curves are generally analyzed theoretically using Newtonian physics; however, two groups of authors have claimed that for self-gravitating dusts, general relativity (GR) makes significantly different predictions to Newtonian physics, even in the weak field, low velocity limit. One group has even gone so far as to claim that nonlinear general relativistic effects can explain flat galactic rotation curves without the need for cold dark matter. These claims seem to contradict the well-known fact that the weak field, low velocity, low pressure correspondence limit of GR is Newtonian gravity, as evidenced by solar system tests. Both groups of authors claim that their conclusions do not contradict this fact, with Cooperstock and Tieu arguing that the reason is that for the solar system, we have test particles orbiting a central gravitating body, whereas for a galaxy, each star is both an orbiting body and a contributor to the net gravitational field, and this supposedly makes a difference due to nonlinear general relativistic effects. Given the significance of these claims for analyses of the flat galactic rotation curve problem, this article compares the predictions of GR and Newtonian gravity for three cases of self-gravitating dusts for which the exact general relativistic solutions are known. These investigations reveal that GR and Newtonian gravity are in excellent agreement in the appropriate limits, thus supporting the conventional use of Newtonian physics to analyze galactic rotation curves. These analyses also reveal some sources of error in the referred to works.

scholarly journals RELXILL_NK: A Black Hole Relativistic Reflection Model for Testing General Relativity

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 7 ◽  
Author(s):  
Askar B. Abdikamalov ◽  
Dimitry Ayzenberg ◽  
Cosimo Bambi  ◽  
Sourabh Nampalliwar
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Relativistic Effects ◽  
Asymptotically Flat ◽  
X Ray ◽  
Black Hole Accretion ◽  
Reflection Model ◽  
Black Hole Spacetime ◽  
General Relativistic ◽  
Hole Accretion

In this paper, we briefly present RELXILL_NK, the first and currently only readily available model of the relativistic reflection spectrum of black hole accretion disks that includes non-Kerr solutions for the black hole spacetime, thus allowing for tests of the Kerr hypothesis and general relativity (GR). RELXILL_NK makes use of a general relativistic ray-tracing code to calculate the relativistic effects of any well-behaved, stationary, axisymmetric, and asymptotically flat black hole spacetime, while the disk physics is handled through the non-relativistic X-ray reflection code XILLVER. A number of different flavors are available within RELXILL_NK; we summarize and compare these flavors using the Johannsen metric for the black hole spacetime.

ON THE EINSTEIN–MAXWELL–THOMAS–FERMI EQUATIONS OF EQUILIBRIUM FOR WHITE DWARFS AND NEUTRON STARS

2013 ◽  
Vol 22 (11) ◽  
pp. 1360007 ◽  
Author(s):  
JORGE A. RUEDA ◽  
REMO RUFFINI
Keyword(s):  
Neutron Stars ◽  
Maxwell Equations ◽  
White Dwarfs ◽  
Recent Progress ◽  
Thomas Fermi ◽  
General Relativistic

We summarize recent progress in the formulation of a theory for white dwarfs and neutron stars taking into account the strong, weak, electromagnetic and gravitational interactions based on the general relativistic Thomas–Fermi equations of equilibrium and the Einstein–Maxwell equations.

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