scholarly journals Neutron stars with a crossover equation of state

2021 ◽  
Vol 104 (1) ◽  
Author(s):  
J. I. Kapusta ◽  
T. Welle
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Crossover Equation Of State

scholarly journals The I-Love-Q Relations for Superfluid Neutron Stars

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 111
Author(s):  
Cheung-Hei Yeung ◽  
Lap-Ming Lin ◽  
Nils Andersson ◽  
Greg Comer
Keyword(s):  
Fluid Dynamics ◽  
Equation Of State ◽  
Neutron Stars ◽  
Quadrupole Moment ◽  
Fluid Model ◽  
Normal Component ◽  
Approximate Equation ◽  
Mean Field Model ◽  
Polytropic Model ◽  
Two Fluid

The I-Love-Q relations are approximate equation-of-state independent relations that connect the moment of inertia, the spin-induced quadrupole moment, and the tidal deformability of neutron stars. In this paper, we study the I-Love-Q relations for superfluid neutron stars for a general relativistic two-fluid model: one fluid being the neutron superfluid and the other a conglomerate of all charged components. We study to what extent the two-fluid dynamics might affect the robustness of the I-Love-Q relations by using a simple two-component polytropic model and a relativistic mean field model with entrainment for the equation-of-state. Our results depend crucially on the spin ratio Ωn/Ωp between the angular velocities of the neutron superfluid and the normal component. We find that the I-Love-Q relations can still be satisfied to high accuracy for superfluid neutron stars as long as the two fluids are nearly co-rotating Ωn/Ωp≈1. However, the deviations from the I-Love-Q relations increase as the spin ratio deviates from unity. In particular, the deviation of the Q-Love relation can be as large as O(10%) if Ωn/Ωp differ from unity by a few tens of percent. As Ωn/Ωp≈1 is expected for realistic neutron stars, our results suggest that the two-fluid dynamics should not affect the accuracy of any gravitational waveform models for neutron star binaries that employ the relation to connect the spin-induced quadrupole moment and the tidal deformability.

scholarly journals Constraining the equation of state of dense nuclear matter using thermal emission of neutron stars

2020 ◽  
Vol 1667 ◽  
pp. 012001
Author(s):  
Nicolas Baillot d’Étivaux ◽  
Jérôme Margueron ◽  
Sebastien Guillot ◽  
Natalie Webb ◽  
Màrcio Catelan ◽  
...  
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Thermal Emission ◽  
Dense Nuclear Matter

scholarly journals Nuclear equation of state and neutron star cooling

2017 ◽  
Vol 26 (04) ◽  
pp. 1750015 ◽  
Author(s):  
Yeunhwan Lim ◽  
Chang Ho Hyun ◽  
Chang-Hwan Lee
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Thermal Evolution ◽  
Observation Data ◽  
Nuclear Equation Of State ◽  
The Core ◽  
Dense Nuclear Matter ◽  
Nuclear Models

In this paper, we investigate the cooling of neutron stars with relativistic and nonrelativistic models of dense nuclear matter. We focus on the effects of uncertainties originated from the nuclear models, the composition of elements in the envelope region, and the formation of superfluidity in the core and the crust of neutron stars. Discovery of [Formula: see text] neutron stars PSR J1614−2230 and PSR J0343[Formula: see text]0432 has triggered the revival of stiff nuclear equation of state at high densities. In the meantime, observation of a neutron star in Cassiopeia A for more than 10 years has provided us with very accurate data for the thermal evolution of neutron stars. Both mass and temperature of neutron stars depend critically on the equation of state of nuclear matter, so we first search for nuclear models that satisfy the constraints from mass and temperature simultaneously within a reasonable range. With selected models, we explore the effects of element composition in the envelope region, and the existence of superfluidity in the core and the crust of neutron stars. Due to uncertainty in the composition of particles in the envelope region, we obtain a range of cooling curves that can cover substantial region of observation data.

scholarly journals Pulsars in Globular Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 291-300 ◽  
Author(s):  
Scott M. Ransom
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Globular Clusters ◽  
Main Sequence ◽  
Galactic Disk ◽  
Nuclear Density ◽  
Millisecond Pulsars ◽  
Eccentric Orbits ◽  
The Masses ◽  
Current Record

AbstractGlobular clusters produce orders of magnitude more millisecond pulsars per unit mass than the Galactic disk. Since the first cluster pulsar was uncovered 20 years ago, at least 138 have been identified – most of which are binary millisecond pulsars. Because their origins involve stellar encounters, many of the systems are exotic objects that would never be observed in the Galactic disk. Examples include pulsar-main sequence binaries, extremely rapid rotators (including the current record holder), and millisecond pulsars in highly eccentric orbits. These systems are allowing new probes of the interstellar medium, the equation of state of material at supra-nuclear density, the masses of neutron stars, and globular cluster dynamics.

scholarly journals Quadrupole moments of rotating compact stars

2012 ◽  
Vol 8 (S291) ◽  
pp. 536-536
Author(s):  
Martin Urbanec ◽  
John Miller ◽  
Zdenek Stuchlik
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Strange Star ◽  
Compact Stars ◽  
Quadrupole Moments ◽  
Strange Stars

AbstractWe present quadrupole moments of rotating neutron and strange stars calculated using standard Hartle Thorne approach. We demonstrate differences between neutron and strange star parameters connected with quadrupole moments and how this parameters could be, in the case of neutron stars, approximated almost independently on neutron star equation of state.

scholarly journals Neutron stars as probes of dark matter

2020 ◽  
Vol 29 (14) ◽  
pp. 2043028
Author(s):  
M. Ángeles Pérez-García ◽  
Joseph Silk
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Equation Of State ◽  
Neutron Stars ◽  
Internal Structure ◽  
Stellar Objects ◽  
Ordinary Matter ◽  
Stable Solutions ◽  
The Universe

Neutron Stars (NSs) are compact stellar objects that are stable solutions in General Relativity. Their internal structure is usually described using an equation of state that involves the presence of ordinary matter and its interactions. However there is now a large consensus that an elusive sector of matter in the universe, described as dark matter, remains as yet undiscovered. In such a case, NSs should contain both, baryonic and dark matter. We argue that depending on the nature of the dark matter and in certain circumstances, the two matter components would form a mixture inside NSs that could trigger further changes, some of them observable. The very existence of NSs constrains the nature and interactions of dark matter in the universe.

scholarly journals Constraints on EOS from finite nuclei, heavy ion collisions and neutron stars

2020 ◽  
Vol 15 ◽  
pp. 196
Author(s):  
T. Gaitanos ◽  
G. Ferini ◽  
M. Colonna ◽  
M. Di Toro ◽  
G. A. Lalazissis ◽  
...  
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Symmetry Energy ◽  
Ground State ◽  
Heavy Ion Collisions ◽  
Heavy Ion ◽  
Intermediate Energy ◽  
Ion Collisions ◽  
Finite Nuclei ◽  
Asymmetric Matter

We present several possibilities offered by nuclear structure, the dynamics of intermediate energy heavy ion collisions and neutron stars to investigate the nuclear matter equation of state (EoS) beyond the ground state. In particular the high density nuclear EoS of asymmetric matter, i.e. the symmetry energy, is discussed.

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