scholarly journals Higher mass limits of neutron stars from the equation of states in curved spacetime

2021 ◽  
Vol 104 (12) ◽  
Author(s):  
Golam Mortuza Hossain ◽  
Susobhan Mandal
Keyword(s):  
Neutron Stars ◽  
Curved Spacetime ◽  
Equation Of States

scholarly journals Revisiting the Post-glitch Relaxation of the 2000 Vela Glitch with the Neutron Star Equation of States in the Brueckner and Relativistic Brueckner Theories

2021 ◽  
Vol 923 (1) ◽  
pp. 108
Author(s):  
Xinle Shang ◽  
Ang Li
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Component Model ◽  
Short Term ◽  
Strong Suppression ◽  
Stellar Radius ◽  
Equation Of States ◽  
Two Component ◽  
Vela Pulsar

Abstract We revisit the short-term post-glitch relaxation of the Vela 2000 glitch in the simple two-component model of the pulsar glitch by making use of the latest realistic equations of states from the microscopic Brueckner and the relativistic Brueckner theories for neutron stars, which can reconcile with the available astrophysical constraints. We show that to fit both the glitch size and the post-glitch jumps in frequency derivatives approximately 1 minute after the glitch, the mass of the Vela pulsar is necessarily small, and there may be demands for a stiff equation of state (which results in a typical stellar radius larger than ∼12.5 km) and a strong suppression of the pairing gap in the nuclear medium. We discuss the implications of this result on the understanding of pulsar glitches.

scholarly journals Application of Information and Complexity Measures to Neutron Stars Structure

2019 ◽  
Vol 18 ◽  
pp. 163
Author(s):  
K. Ch. Chatzisavvas ◽  
V. P. Psonis ◽  
C. P. Panos ◽  
Ch. C. Moustakidis
Keyword(s):  
Gravitational Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
Short Range ◽  
Nuclear Force ◽  
Low Complexity ◽  
Complexity Measures ◽  
Astronomical Observations ◽  
Equation Of States ◽  
Statistical Complexity

We apply several information and statistical complexity measures to neutron stars structure. Neutron stars is a classical example where the gravitational field and quantum behaviour are combined and produce a macroscopic dense object. We concentrate our study on the connection between complexity and neutron star properties, like maximum mass and the corresponding radius, applying a specific set of realistic equation of states. Moreover, the effect of the strength of the gravitational field on the neutron star structure and consequently on the complexity measure is also investigated. It is seen that neutron stars, consistent with astronomical observations so far, are ordered systems (low complexity), which cannot grow in complexity as their mass increases. This is a result of the interplay of gravity, the short-range nuclear force and the very short-range weak interaction.

scholarly journals Simulating Binary Neutron Stars with Hybrid Equation of States: Gravitational Waves, Electromagnetic Signatures and Challenges for Numerical Relativity

Particles ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 365-384 ◽  
Author(s):  
Henrique Gieg ◽  
Tim Dietrich ◽  
Maximiliano Ujevic
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Quark Matter ◽  
Strange Quark ◽  
Numerical Relativity ◽  
Strange Quark Matter ◽  
Strong Phase ◽  
Equation Of States

The gravitational wave and electromagnetic signatures connected to the merger of two neutron stars allow us to test the nature of matter at supranuclear densities. Since the Equation of State governing the interior of neutron stars is only loosely constrained, there is even the possibility that strange quark matter exists inside the core of neutron stars. We investigate how strange quark matter cores affect the binary neutron star coalescence by performing numerical relativity simulations. Interestingly, the strong phase transition can cause a reduction of the convergence order of the numerical schemes to first order if the numerical resolution is not high enough. Therefore, an additional challenge is added in producing high-quality gravitational wave templates for Equation of States with a strong phase transition. Focusing on one particular configuration of an equal mass configuration consistent with GW170817, we compute and discuss the associated gravitational wave signal and some of the electromagnetic counterparts connected to the merger of the two stars. We find that existing waveform approximants employed for the analysis of GW170817 allow describing this kind of systems within the numerical uncertainties, which, however, are several times larger than for pure hadronic Equation of States, which means that even higher resolutions have been employed for an accurate gravitational wave model comparison. We also show that for the chosen Equation of State, quasi-universal relations describing the gravitational wave emission after the moment of merger seem to hold and that the electromagnetic signatures connected to our chosen setup would not be bright enough to explain the kilonova associated to GW170817.

scholarly journals ONE POSSIBLE MECHANISM FOR MASSIVE NEUTRON STAR SUPPORTED BY SOFT EOS

2012 ◽  
Vol 21 (04) ◽  
pp. 1250036 ◽  
Author(s):  
DE-HUA WEN ◽  
JING YAN ◽  
XUE-MEI LIU
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Constant ◽  
Strong Field ◽  
Laboratory Data ◽  
Nuclear Theory ◽  
Equation Of States ◽  
Massive Neutron Star

The recently discovery of a massive neutron star (PSR J1614-2230 of 1.97 ± 0.04 M⊙) rules out the soft equation-of-states (EOSs) such as those included hyperons or kaon condensates at high densities, while the nuclear theory or the terrestrial laboratory data prefer a soft EOS. Here we propose one possible mechanism to allow that the observed massive neutron star can be supported by a soft EOS, that is, if the gravitational constant G varies at super strong field, a soft EOS can support the massive neutron stars.

KEPLERIAN FREQUENCY OF UNIFORMLY ROTATING NEUTRON STARS IN RELATIVISTIC MEAN FIELD THEORY

2013 ◽  
Vol 22 (11) ◽  
pp. 1350085 ◽  
Author(s):  
N. B. ZHANG ◽  
B. QI ◽  
S. Y. WANG ◽  
S. L. GE ◽  
B. Y. SUN
Keyword(s):  
Field Theory ◽  
Neutron Stars ◽  
Empirical Formula ◽  
Mean Field Theory ◽  
Mean Field ◽  
Gravitational Mass ◽  
Relativistic Mean Field Theory ◽  
Relativistic Mean Field ◽  
Equation Of States

Adopting the equation of states (EOSs) from the relativistic mean field (RMF) theory, the relationships among the keplerian frequency fK, gravitational mass M and radius R for the rapidly rotating neutron stars with and without hyperons are presented and analyzed. For various RMF EOSs, the empirical formula [Formula: see text], proposed by P. Haensel et al. [Astron. Astrophys.502 (2009) 605], is found to be an approximation with the error at most 13% and such approximation is worse for the neutron stars with hyperons. It indicates that the errors should be considered when the empirical formula is used to discuss the properties of neutron stars.

scholarly journals Quiescent luminosities of accreting neutron stars with different equation of states

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Helei Liu ◽  
Akira Dohi ◽  
Masa-aki Hashimoto ◽  
Yasuhide Matsuo ◽  
Guo-Liang Lü ◽  
...  
Keyword(s):  
Neutron Stars ◽  
Equation Of States

Neutron Stars and "Black Holes"

1973 ◽  
Vol 110 (7) ◽  
pp. 441 ◽  
Author(s):  
Ya.B. Zel'dovich
Keyword(s):  
Black Holes ◽  
Neutron Stars

Cooling of neutron stars and superfluidity in their cores

1999 ◽  
Vol 169 (8) ◽  
pp. 825 ◽  
Author(s):  
Dmitrii G. Yakovlev ◽  
Kseniya P. Levenfish ◽  
Yurii A. Shibanov
Keyword(s):  
Neutron Stars
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