scholarly journals Anisotropic Heat Transfer Inside Rotating Neutron Stars

2004 ◽  
Vol 218 ◽  
pp. 39-40
Author(s):  
C. Y. Hui ◽  
K. S. Cheng

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.

Symmetry ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 189
Author(s):  
Alexander Balakin ◽  
Alexei Ilin ◽  
Anna Kotanjyan ◽  
Levon Grigoryan

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.


2019 ◽  
Vol 487 (4) ◽  
pp. 5129-5142 ◽  
Author(s):  
D A Bollimpalli ◽  
M Wielgus ◽  
D Abarca ◽  
W Kluźniak

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.


1987 ◽  
Vol 125 ◽  
pp. 55-55
Author(s):  
Kai You Chen ◽  
Jacob Shaham

By considering a simple model of slowly rotating neutron stars (for which the Schwartzschild metric could be used properly) whose emission is confined to circular antipolar caps, Pechenick, Ftaclas and Cohen (1983) studied the gravitational effects on the light curves. They found that for typical neutron star parameters, the light curves flattened out due to the bending of light in the neutron stellar gravity.


1981 ◽  
Vol 93 ◽  
pp. 327-327
Author(s):  
Kenzo Arai ◽  
Keisuke Kaminishi

The dynamical equations governing pulsation in rotating neutron stars are derived in the framework of general relativity. Stellar models are constructed by using a realistic equation of state for cold neutron matter. Small radial displacement and slow rotation are treated as perturbations on spherically symmetric body. In these models the maximum masses are 1.761 M⊙ at the central density 3.461 × 1015 g cm−3 for a sequence of nonrotating configurations and 2.165 M⊙ for rotating models with the critical angular velocity (GM/R3)½.


2019 ◽  
Vol 35 (09) ◽  
pp. 2050056 ◽  
Author(s):  
Javlon Rayimbaev ◽  
Bobur Turimov ◽  
Figueroa Marcos ◽  
Satimbay Palvanov ◽  
Azamkhan Rakhmatov

Neutron stars (NS)s are astrophysical objects with strong gravitational and electromagnetic fields. Since there are several effects on radiation processes around the star, it is impossible to consider whole effects all together. One way to study the processes is by considering them one by one as a toy model. In this paper, we have investigated the effects of spacetime deformation on the surface magnetic field of the slowly rotating neutron star and its plasma magnetospheric processes, such as the plasma magnetosphere formation around the star. At first, the approximate vacuum solutions of the Maxwell equations for the electromagnetic fields of a magnetized neutron star in a slowly rotating deformed spacetime metric have been obtained. It has been shown that the positive deformation parameter leads to an increase in the value of the (surface) magnetic field at the near zone of the neutron star, while the effect of the negative deformation parameter is vice versa. We have also considered the electric field of the slowly rotating neutron star in the spacetime. In the slow rotation approximation, we have studied the particle acceleration in the polar cap zone, considering the effect of deformation of spacetime on the [Formula: see text]-Lorentz factor of a relativistic charged particle. It is shown that in the case of the positive deformation, an additional gravity occurs around the NS. The effects of spacetime deformation on magneto-dipolar radiation of radio pulsars and polar cap size have also been studied and shown that negative deformation of spacetime increased the radiation luminosity and as positive deformation increases, the luminosity decreases. Size of polar cap region of a neutron star, where magnetic field lines open, increases with increasing the value of the deformation parameter [Formula: see text]. Moreover, we have studied the influence of the spacetime deformation on the death line for radio pulsar, which separates the region in [Formula: see text] [Formula: see text] diagram, where the pulsar can or cannot radiate in radio band (create pair production) through inverse compton scattering (ICS). It is shown that the negative (positive) deformation shifts upward (downward) the death line, which means that even a small negative (positive) deformation of spacetime may cause to be radio-quite (be radio load) the radio pulsar which is lying on the death line (in [Formula: see text] diagram) in the GR frame with its corresponding parameters.


Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 97
Author(s):  
Nils Andersson

We provide a bird’s-eye view of neutron-star seismology, which aims to probe the extreme physics associated with these objects, in the context of gravitational-wave astronomy. Focussing on the fundamental mode of oscillation, which is an efficient gravitational-wave emitter, we consider the seismology aspects of a number of astrophysically relevant scenarios, ranging from transients (like pulsar glitches and magnetar flares), to the dynamics of tides in inspiralling compact binaries and the eventual merged object and instabilities acting in isolated, rapidly rotating, neutron stars. The aim is not to provide a thorough review, but rather to introduce (some of) the key ideas and highlight issues that need further attention.


1980 ◽  
Vol 4 (1) ◽  
pp. 49-50
Author(s):  
R. A. Gingold ◽  
J. J. Monaghan

Misner Thorne and Wheeler (1973), (page 629) suggested that a freshly formed White Dwarf star of several solar masses would, if slowly — rotating, collapse to form a neutron star pancake which would become unstable and eventually produce several, possibly colliding, neutron stars.


1953 ◽  
Vol 9 (1) ◽  
pp. 13-16 ◽  
Author(s):  
Paul Kustaanheimo

SummaryIt is shown that every spherically symmetric metric can be transformed into the isotropic form. As illustration an example is given.


2013 ◽  
Vol 88 (4) ◽  
Author(s):  
Kenta Hotokezaka ◽  
Kenta Kiuchi ◽  
Koutarou Kyutoku ◽  
Takayuki Muranushi ◽  
Yu-ichiro Sekiguchi ◽  
...  

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