scholarly journals General Relativistic Effects on the Ohmic Decay of Crustal Magnetic Fields in Neutron Stars

1997 ◽  
Vol 479 (2) ◽  
pp. L133-L136 ◽  
Author(s):  
Sujan Sengupta
Keyword(s):  
Magnetic Fields ◽  
Neutron Stars ◽  
Relativistic Effects ◽  
General Relativistic

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.

scholarly journals Equatorial Geodesics Around the Magnetars

2017 ◽  
Vol 45 ◽  
pp. 1760050
Author(s):  
Viviane A. P. Alfradique ◽  
Orlenys N. Troconis ◽  
Rodrigo P. Negreiros
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Complete Solution ◽  
Compact Object ◽  
Relativistic Effects ◽  
Schwarzschild Solution ◽  
Soft Gamma Repeaters ◽  
Definition Of ◽  
The Magnetic Field

Neutron stars manifest themselves as different classes of astrophysical sources that are associated to distinct phenomenology. Here we focus our attention on magnetars (or strongly magnetized neutron stars) that are associated to Soft Gamma Repeaters and Anomalous X-ray Pulsars. The magnetic field on surface of these objects, reaches values greater than [Formula: see text] G. Under intense magnetic fields, relativistic effects begin to be decisive for the definition of the structure and evolution of these objects. We are tempted to question ourselves to how strengths fields affect the structure of neutron star. In this work, our objective is study and compare two solutions of Einstein-Maxwell equations: the Bonnor solution, which is an analytical solution that describe the exterior spacetime for a massive compact object which has a magnetic field that is characterize as a dipole field and a complete solution that describe the interior and exterior spacetime for the same source found by numerical methods). For this, we describe the geodesic equations generated by such solutions. Our results show that the orbits generated by the Bonnor solution are the same as described by numerical solution. Also, show that the inclusion of magnetic fields with values up to [Formula: see text]G in the center of the star does not modify sharply the particle orbits described around this star, so the use of Schwarzschild solution for the description of these orbits is a reasonable approximation.

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 Axisymmetric equilibrium models for magnetised neutron stars in scalar-tensor theories

2020 ◽  
Vol 640 ◽  
pp. A44 ◽  
Author(s):  
J. Soldateschi ◽  
N. Bucciantini ◽  
L. Del Zanna
Keyword(s):  
General Relativity ◽  
Magnetic Fields ◽  
Neutron Stars ◽  
Scalar Fields ◽  
Flat Condition ◽  
General Relativistic ◽  
Axisymmetric Equilibrium ◽  
First Time ◽  
Poloidal Magnetic Fields ◽  
The Universe

Among the possible extensions of general relativity that have been put forward to address some long-standing issues in our understanding of the Universe, scalar-tensor theories have received a lot of attention for their simplicity. Interestingly, some of these predict a potentially observable non-linear phenomenon, known as spontaneous scalarisation, in the presence of highly compact matter distributions, as in the case of neutron stars. Neutron stars are ideal laboratories for investigating the properties of matter under extreme conditions and, in particular, they are known to harbour the strongest magnetic fields in the Universe. Here, for the first time, we present a detailed study of magnetised neutron stars in scalar-tensor theories. First, we showed that the formalism developed for the study of magnetised neutron stars in general relativity, based on the “extended conformally flat condition”, can easily be extended in the presence of a non-minimally coupled scalar field, retaining many of its numerical advantages. We then carried out a study of the parameter space considering the two extreme geometries of purely toroidal and purely poloidal magnetic fields, varying both the strength of the magnetic field and the intensity of scalarisation. We compared our results with magnetised general-relativistic solutions and un-magnetised scalarised solutions, showing how the mutual interplay between magnetic and scalar fields affect the magnetic and the scalarisation properties of neutron stars. In particular, we focus our discussion on magnetic deformability, maximum mass, and range of scalarisation.

scholarly journals General Relativistic Effects on Neutrino‐driven Winds from Young, Hot Neutron Stars andr‐Process Nucleosynthesis

2000 ◽  
Vol 533 (1) ◽  
pp. 424-439 ◽  
Author(s):  
Kaori Otsuki ◽  
Hideyuki Tagoshi ◽  
Toshitaka Kajino ◽  
Shin‐ya Wanajo
Keyword(s):  
Neutron Stars ◽  
Relativistic Effects ◽  
General Relativistic

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.

Origin of Magnetic Fields in White Dwarfs and Neutron Stars

1971 ◽  
Vol 231 (19) ◽  
pp. 32-33 ◽  
Author(s):  
R. F. O'CONNELL ◽  
K. M. ROUSSEL
Keyword(s):  
Magnetic Fields ◽  
Neutron Stars ◽  
White Dwarfs
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