scholarly journals Thermal properties of hot and dense matter: Influence of rapid rotation on protoneutron stars, hot neutron stars, and neutron star merger remnants

2021 ◽  
Vol 252 ◽  
pp. 05004
Author(s):  
Polychronis Koliogiannis ◽  
Charalampos Moustakidis
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Equations Of State ◽  
Interaction Model ◽  
Dense Matter ◽  
Baryon Density ◽  
Dense Nuclear Matter ◽  
Protoneutron Stars

The knowledge of the equation of state is a key ingredient for many dynamical phenomena that depend sensitively on the hot and dense nuclear matter, such as the formation of protoneutron stars and hot neutron stars. In order to accurately describe them, we construct equations of state at FInite temperature and entropy per baryon for matter with varying proton fractions. This procedure is based on the momentum dependent interaction model and state-of-the-art microscopic data. In addition, we investigate the role of thermal and rotation effects on microscopic and macroscopic properties of neutron stars, including the mass and radius, the frequency, the Kerr parameter, the central baryon density, etc. The latter is also connected to the hot and rapidly rotating remnant after neutron star merger. The interplay between these quantities and data from late observations of neutron stars, both isolated and in matter of merging, could provide useful insight and robust constraints on the equation of state of nuclear matter.

scholarly journals Hard-Core Radius of Nucleons within the Induced Surface Tension Approach

Universe ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 63 ◽  
Author(s):  
Kyrill Bugaev ◽  
Aleksei Ivanytskyi ◽  
Violetta Sagun ◽  
Boris Grinyuk ◽  
Denis Savchenko ◽  
...  
Keyword(s):  
Surface Tension ◽  
Nuclear Matter ◽  
Equations Of State ◽  
Hard Core ◽  
Blocking Effect ◽  
Composite Particles ◽  
Core Radius ◽  
Pauli Blocking ◽  
Novel Approach ◽  
Recent Approach

We review the recent approach to model the hadronic and nuclear matter equations of state using the induced surface tension concept, which allows one to go far beyond the usual Van der Waals approximation. Since the obtained equations of state, classical and quantum, are among the most successful ones in describing the properties of low density phases of strongly interacting matter, they set strong restrictions on the possible value of the hard-core radius of nucleons, which is widely used in phenomenological equations of state. We summarize the latest results obtained within this novel approach and perform a new detailed analysis of the hard-core radius of nucleons, which follows from hadronic and nuclear matter properties. Such an analysis allows us to find the most trustworthy range of its values: the hard-core radius of nucleons is 0.3–0.36 fm. A comparison with the phenomenology of neutron stars implies that the hard-core radius of nucleons has to be temperature and density dependent. Such a finding is supported when the eigenvolume of composite particles like hadrons originates from their fermionic substructure due to the Pauli blocking effect.

POINT-COUPLING AND NONLINEAR WALECKA MODELS CONNECTION

2007 ◽  
Vol 16 (09) ◽  
pp. 3037-3040 ◽  
Author(s):  
O. LOURENÇO ◽  
M. DUTRA ◽  
A. DELFINO ◽  
R. L. P. G. AMARAL
Keyword(s):  
Nuclear Matter ◽  
Equations Of State ◽  
Mean Field ◽  
Coupling Model ◽  
Equation Of States ◽  
Theoretical Support ◽  
Naive Dimensional Analysis ◽  
Spectra Properties ◽  
Finite Nuclei ◽  
Walecka Model

In the context of infinite nuclear matter, the equation of states obtained from the Walecka model turn out to be the same as those constructed from point-coupling models in which the nucleons interact with each other only when they are in contact.1 Nonlinear point-coupling models have been applied sucessfully to describe infinite nuclear matter and finite nuclei spectra properties.2 A theoretical support for this was presented on the basis of naturalness and naive dimensional analysis.3 For the usual linear Walecka model the infinite meson masses limit leads to a point-coupling model. From this, a quite natural question arises, whether the same kind of masses limit taken in a nonlinear Walecka model would provide a point-coupling model. We construct a modified nonlinear Walecka model Lagrangian in which the infinite meson masses limit can be taken exactly and leads to the contact nonlinear model. This modified nonlinear Walecka model includes higher order couplings. Although the modified and the nonlinear Walecka model at a mean field approach lead to distinct equations of state, the physically relevant content of the models are the same.

scholarly journals Constraints on the speed of sound of dense nuclear matter through the tidal deformability of neutron stars

2021 ◽  
Vol 252 ◽  
pp. 05005
Author(s):  
Alkiviadis Kanakis-Pegios ◽  
Polychronis Koliogiannis ◽  
Charalampos Moustakidis
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Speed Of Sound ◽  
Nuclear Physics ◽  
Equations Of State ◽  
Open Problems ◽  
Binary Neutron Star ◽  
Dense Nuclear Matter

One of the greatest interest and open problems in nuclear physics is the upper limit of the speed of sound in dense nuclear matter. Neutron stars, both in isolated and binary system cases, constitute a very promising natural laboratory for studying this kind of problem. This present work is based on one of our recent study, regarding the speed of sound and possible constraints that we can obtain from neutron stars. To be more specific, in the core of our study lies the examination of the speed of sound through the measured tidal deformability of a binary neutron star system (during the inspiral phase). The relation between the maximum neutron star mass scenario and the possible upper bound on the speed of sound is investigated. The approach that we used follows the contradiction between the recent observations of binary neutron star systems, in which the effective tidal deformability favors softer equations of state, while the high measured masses of isolated neutron stars favor stiffer equations of state. In our approach, we parametrized the stiffness of the equation of state by using the speed of sound. Moreover, we used the two recent observations of binary neutron star mergers from LIGO/VIRGO, so that we can impose robust constraints on the speed of sound. Furthermore, we postulate the kind of future measurements that could be helpful by imposing more stringent constraints on the equation of state.

scholarly journals Neutron Stars and the Nuclear Matter Equation of State

2021 ◽  
Vol 71 (1) ◽  
Author(s):  
J.M. Lattimer
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Equations Of State ◽  
Radioactive Decay ◽  
Dense Matter ◽  
Annual Review ◽  
Publication Date ◽  
Pulse Profile ◽  
Dense Nuclear Matter

Neutron stars provide a window into the properties of dense nuclear matter. Several recent observational and theoretical developments provide powerful constraints on their structure and internal composition. Among these are the first observed binary neutron star merger, GW170817, whose gravitational radiation was accompanied by electromagnetic radiation from a short γ-ray burst and an optical afterglow believed to be due to the radioactive decay of newly minted heavy r-process nuclei. These observations give important constraints on the radii of typical neutron stars and on the upper limit to the neutron star maximum mass and complement recent pulsar observations that established a lower limit. Pulse-profile observations by the Neutron Star Interior Composition Explorer (NICER) X-ray telescope provide an independent, consistent measure of the neutron star radius. Theoretical many-body studies of neutron matter reinforce these estimates of neutron star radii. Studies using parameterized dense matter equations of state (EOSs) reveal several EOS-independent relations connecting global neutron star properties. Expected final online publication date for the Annual Review of Nuclear and Particle Science, Volume 71 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals PHASE TRANSITION AND HYBRID STAR IN A NONLINEAR σ–ω MODEL

1999 ◽  
Vol 08 (02) ◽  
pp. 107-120 ◽  
Author(s):  
S. ACHARYA ◽  
L. MAHARANA ◽  
R. MOHANTY ◽  
P. K. PANDA
Keyword(s):  
Phase Transition ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Equations Of State ◽  
Mean Field Theory ◽  
Mean Field ◽  
Coupling Constant ◽  
Hybrid Star ◽  
Relativistic Mean Field ◽  
Outer Periphery

The phase transition between nuclear matter and quark matter is examined. The relativistic mean field theory (RMF) is considered with interacting nucleons and mesons using TM1 parameter set for the nuclear matter equations of state. It is found that the transition point depends on coupling constant αs and bag pressure. From the study of the structure of a hybrid neutron star, it is observed that the star contains quark matter in the interior and neutron matter on the outer periphery.

scholarly journals Chirally Improved Quark Pauli Blocking in Nuclear Matter and Applications to Quark Deconfinement in Neutron Stars

Particles ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 477-499 ◽  
Author(s):  
David Blaschke ◽  
Hovik Grigorian ◽  
Gerd Röpke
Keyword(s):  
Nuclear Matter ◽  
Equations Of State ◽  
Compact Star ◽  
Mean Field ◽  
High Mass ◽  
Pauli Blocking ◽  
Density Dependent ◽  
Relativistic Mean Field ◽  
Njl Model ◽  
Rmf Model

The relativistic mean field (RMF) model of the nuclear matter equation of state was modified by including the effect of Pauli-blocking owing to quark exchange between the baryons. Different schemes of a chiral enhancement of the quark Pauli blocking was suggested according to the adopted density dependence of the dynamical quark mass. The resulting equations of state for the pressure are compared to the RMF model DD2 with excluded volume correction. On the basis of this comparison a density-dependent nucleon volume is extracted which parameterizes the quark Pauli blocking effect in the respective scheme of chiral enhancement. The dependence on the isospin asymmetry is investigated and the corresponding density dependent nuclear symmetry energy is obtained in fair accordance with phenomenological constraints. The deconfinement phase transition is obtained by a Maxwell construction with a quark matter phase described within a higher order NJL model. Solutions for rotating and nonrotating (hybrid) compact star sequences are obtained, which show the effect of high-mass twin compact star solutions for the rotating case.

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