QUARK MATTER NUCLEATION AT NEUTRON STAR CORES: RELEVANCE OF ENERGY-DENSITY FLUCTUATIONS

2011 ◽  
Vol 20 (supp01) ◽  
pp. 167-174 ◽  
Author(s):  
GERMAN LUGONES ◽  
ANA G. GRUNFELD
Keyword(s):  
Neutron Star ◽  
Energy Density ◽  
Quark Matter ◽  
Critical Size ◽  
Finite Size ◽  
Density Fluctuations ◽  
Hadronic Matter ◽  
Size Spectrum ◽  
Critical Bubble ◽  
Protoneutron Star

We study the deconfinement of hadronic matter into quark matter in a protoneutron star focusing on the effects of the finite size on the formation of just-deconfined color superconducting quark droplets embedded in the hadronic environment. We show that energy-density fluctuations are much more relevant for deconfinement than temperature and neutrino density fluctuations. We calculate the critical size spectrum of energy-density fluctuations that allows deconfinement as well as the nucleation rate of each critical bubble. We find that drops with any radii smaller than 800 fm can be formed at a huge rate when matter achieves the bulk transition limit of 5–6 times the nuclear saturation density.

scholarly journals Contraction of cold neutron star due to in the presence a quark core

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
B. Eslam Panah ◽  
T. Yazdizadeh ◽  
G. H. Bordbar
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Quark Matter ◽  
Average Density ◽  
Dynamical Stability ◽  
Hadronic Matter ◽  
Maximum Mass ◽  
Quark Core ◽  
Hybrid Stars ◽  
Schwarzschild Radius

Abstract Motivated by importance of the existence of quark matter on structure of neutron star. For this purpose, we use a suitable equation of state (EoS) which include three different parts: (i) a layer of hadronic matter, (ii) a mixed phase of quarks and hadrons, and, (iii) a strange quark matter in the core. For this system, in order to do more investigation of the EoS, we evaluate energy, Le Chatelier’s principle and stability conditions. Our results show that the EoS satisfies these conditions. Considering this EoS, we study the effect of quark matter on the structure of neutron stars such as maximum mass and the corresponding radius, average density, compactness, Kretschmann scalar, Schwarzschild radius, gravitational redshift and dynamical stability. Also, considering the mentioned EoS in this paper, we find that the maximum mass of hybrid stars is a little smaller than that of the corresponding pure neutron star. Indeed the maximum mass of hybrid stars can be quite close to the pure neutron stars. Our calculations about the dynamical stability show that these stars are stable against the radial adiabatic infinitesimal perturbations. In addition, our analyze indicates that neutron stars are under a contraction due to the existence of quark core.

scholarly journals Deconfinement of nonstrange hadronic matter with nucleons and Δ baryons to quark matter in neutron stars

2019 ◽  
Vol 28 (02) ◽  
pp. 1950040 ◽  
Author(s):  
Debashree Sen ◽  
T. K. Jha
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Quark Matter ◽  
Mean Field ◽  
Static Condition ◽  
Hadronic Matter ◽  
Chiral Model ◽  
Vector Coupling ◽  
Binary Neutron Star ◽  
Relativistic Mean Field

We explore the possibility of formation of [Formula: see text] baryons (1232[Formula: see text]MeV) in neutron star matter in an effective chiral model within the relativistic mean-field framework. With variation in delta-meson couplings, consistent with the constraints imposed on them, the resulting equation-of-state (EoS) is obtained and the neutron star properties are calculated for static and spherical configuration. Within the framework of our model, the critical densities of formation of [Formula: see text] and the properties of neutron stars (NS) are found to be very sensitive to the iso-vector coupling compared to the scalar or vector couplings. We revisit the [Formula: see text] puzzle and look for the possibility of phase transition from nonstrange hadronic matter (including nucleons and [Formula: see text]) to deconfined quark matter, based on QCD theories. The resultant hybrid star configurations satisfy the observational constraints on mass from the most massive pulsars PSR J1614-2230 and PSR J0348+0432 in static condition obtained with the general hydrostatic equilibrium based on GTR. Our radius estimates are well within the limits imposed from observational analysis of QLMBXs. The obtained values of [Formula: see text] are in agreement with the recent bounds specified from the observation of gravitational wave (GW170817) from binary neutron star merger. The constraint on baryonic mass from the study of binary system PSR J0737-3039 is also satisfied with our hybrid EoS.

QUARK MATTER IN NEUTRON STARS: AN APERÇU

2006 ◽  
Vol 21 (26) ◽  
pp. 1965-1979 ◽  
Author(s):  
PRASHANTH JAIKUMAR ◽  
SANJAY REDDY ◽  
ANDREW W. STEINER
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Quark Matter ◽  
Finite Size ◽  
Coulomb Energy ◽  
Quark Stars ◽  
Dense Quark Matter ◽  
Intermediate Fraction ◽  
State Of Matter

The existence of deconfined quark matter in the superdense interior of neutron stars is a key question that has drawn considerable attention over the past few decades. Quark matter can comprise an arbitrary fraction of the star, from 0 for a pure neutron star to 1 for a pure quark star, depending on the equation of state of matter at high density. From an astrophysical viewpoint, these two extreme cases are generally expected to manifest different observational signatures. An intermediate fraction implies a hybrid star, where the interior consists of mixed or homogeneous phases of quark and nuclear matter, depending on surface and Coulomb energy costs, as well as other finite size and screening effects. In this review, we discuss what we can deduce about quark matter in neutron stars in light of recent exciting developments in neutron star observations. We state the theoretical ideas underlying the equation of state of dense quark matter, including color superconducting quark matter. We also highlight recent advances stemming from re-examination of an old paradigm for the surface structure of quark stars and discuss possible evolutionary scenarios from neutron stars to quark stars, with emphasis on astrophysical observations.

scholarly journals Impact of quark deconfinement in neutron star mergers and hybrid star mergers

2020 ◽  
Vol 229 (22-23) ◽  
pp. 3595-3604
Author(s):  
Andreas Bauswein ◽  
Sebastian Blacker
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Quark Matter ◽  
Hadronic Matter ◽  
Hybrid Star ◽  
Strong Phase ◽  
Quark Deconfinement ◽  
Wave Signature ◽  
Quark Phase

AbstractWe describe an unambiguous gravitational-wave signature to identify the occurrence of a strong phase transition from hadronic matter to deconfined quark matter in neutron star mergers. Such a phase transition leads to a strong softening of the equation of state and hence to more compact merger remnants compared to purely hadronic models. If a phase transition takes place during merging, this results in a characteristic increase of the dominant postmerger gravitational-wave frequency relative to the tidal deformability characterizing the inspiral phase. By comparing results from different purely hadronic and hybrid models we show that a strong phase transition can be identified from a single, simultaneous measurement of pre- and postmerger gravitational waves. Furthermore, we present new results for hybrid star mergers, which contain quark matter already during the inspiral stage. Also for these systems we find that the postmerger GW frequency is increased compared to purely hadronic models. We thus conclude that also hybrid star mergers with an onset of the hadron-quark phase transition at relatively low densities may lead to the very same characteristic signature of quark deconfinement in the postmerger GW signal as systems undergoing the phase transition during merging.

scholarly journals Was GW170817 a Canonical Neutron Star Merger? Bayesian Analysis with a Third Family of Compact Stars

Universe ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 81 ◽  
Author(s):  
David Blaschke ◽  
Alexander Ayriyan ◽  
David Alvarez-Castillo ◽  
Hovik Grigorian
Keyword(s):  
Neutron Star ◽  
Bayesian Analysis ◽  
Quark Matter ◽  
Compact Star ◽  
Mass Range ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Binary Mergers ◽  
Hybrid Stars ◽  
First Time

We investigate the possibility that GW170817 was not the merger of two conventional neutron stars (NS), but involved at least one if not two hybrid stars with a quark matter core that might even belong to a third family of compact stars. To this end, we develop a Bayesian analysis method for selecting the most probable equation of state (EoS) under a set of constraints from compact star physics, which now also include the tidal deformability from GW170817 and the first result for the mass and radius determination for PSR J0030+0451 by the NICER Collaboration. We apply this method for the first time to a two-parameter family of hybrid EoS based on the DD2 model with nucleonic excluded volume for hadronic matter and the color superconducting generalized nlNJL model for quark matter. The model has a variable onset density for deconfinement and can mimic the effects of pasta phases with the possibility of producing a third family of hybrid stars in the mass-radius diagram. The main findings of this study are that: (1) the presence of multiple configurations for a given mass (twins or even triples) corresponds to a set of disconnected lines in the Λ 1 – Λ 2 diagram of tidal deformabilities for binary mergers, so that merger events from the same mass range may result in a probability landscape with different peak positions; (2) the Bayesian analysis with the above observational constraints favors an early onset of the deconfinement transition, at masses of M onset ≤ 0.8 M ⊙ with an M–R relationship that in the range of observed neutron star masses is almost indistinguishable from that of a soft hadronic Akmal, Pandharipande, and Ravenhall (APR) EoS; (3) a few, yet fictitious measurements of the NICER experiment two times more accurate than the present value and a different mass and radius that would change the posterior likelihood so that hybrid EoS with a phase transition onset in the range M onset = 1.1–1.6 M ⊙ would be favored.

Radial oscillation of compact stars in the presence of magnetic field

2016 ◽  
Vol 25 (06) ◽  
pp. 1650037 ◽  
Author(s):  
R. C. Baral ◽  
K. K. Mohanta ◽  
N. R. Panda ◽  
P. K. Sahu
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Quark Matter ◽  
Mean Field Theory ◽  
Mean Field ◽  
Compact Objects ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Radial Pulsation ◽  
Maximum Mass

Compact stars are classified into three categories: neutron stars (NSs), quark stars (QSs) and hybrid stars (HSs). Stars having only hadronic matter are NSs, QSs having only quark matter up to u, d and s quarks and stars having quark core surrounded by a mixed matter (hadronic matter and quark matter) followed by hadronic matter are HSs. The mixed matter is well distributed to both hadron and quark matters. A huge magnetic field is predicted in the core of the neutron star and is observed in the surface of the neutron star. We study the effect of such huge magnetic field in the matter inside the compact objects basically the equation of state (EOS) of the matters. Since matter inside the star are very dense both hadronic and quark matter, we consider relativistic mean field theory in the hadronic matter and simple MIT bag model in the quark matter in the presence of strong magnetic field. We calculate the phase transition between hadronic and quark phases, maximum mass and eigenfrequencies of radial pulsation of NS, HS and QS in the presence of such a huge magnetic field. The mixed phase is constructed by using Glendenning conjecture in between hadron and quark phases. We find in the presence of magnetic field, the EOS in both matter becomes soft. As a result, the maximum mass is reduced and the period of oscillation is changed significantly and there is a sudden dip in the period of oscillations in the HS, which signifies the transition from one to another matter.

Protoneutron Star Formation

1988 ◽  
Vol 7 (4) ◽  
pp. 371-381
Author(s):  
Adam Burrows
Keyword(s):  
Star Formation ◽  
Neutron Star ◽  
General Analysis ◽  
Sn 1987A ◽  
Supernova Neutrino ◽  
Neutrino Theory ◽  
Protoneutron Star

AbstractThe theory of neutron star formation is addressed in the light of the detected neutrino burst from SN 1987A. A brief review of how supernova neutrino theory has evolved over the last 30 years and a general analysis of the SN 1987A detections is presented.

Quark Clustering and Chiral Symmetry Breaking in Nuclear Matter

2003 ◽  
Vol 18 (32) ◽  
pp. 2255-2264 ◽  
Author(s):  
O. A. Battistel ◽  
G. Krein
Keyword(s):  
Symmetry Breaking ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Chiral Symmetry ◽  
Quark Matter ◽  
Traditional Approach ◽  
Chiral Symmetry Breaking ◽  
Quark Condensate ◽  
Baryon Density ◽  
Hadronic Matter

Chiral symmetry breaking at finite baryon density is usually discussed in the context of quark matter, i.e. a system of deconfined quarks. Many systems like stable nuclei and neutron stars however have quarks confined within nucleons. In this paper we construct a Fermi sea of three-quark nucleon clusters and investigate the change of the quark condensate as a function of baryon density. We study the effect of quark clustering on the in-medium quark condensate and compare results with the traditional approach of modeling hadronic matter in terms of a Fermi sea of deconfined quarks.

scholarly journals NEUTRINO EMISSION IN INHOMOGENEOUS PION CONDENSED QUARK MATTER

2008 ◽  
Vol 17 (09) ◽  
pp. 1906-1916 ◽  
Author(s):  
XUGUANG HUANG ◽  
QUN WANG ◽  
PENGFEI ZHUANG
Keyword(s):  
Neutron Star ◽  
Specific Heat ◽  
Cooling Rate ◽  
Condensed Phase ◽  
Quark Matter ◽  
Baryon Density ◽  
Neutrino Emission ◽  
Neutrino Emissivity

It is believed that quark matter can exist in neutron star interior if the baryon density is high enough. When there is a large isospin density, quark matter could be in a pion condensed phase. We compute neutrino emission from direct Urca processes in such a phase, particularly in the inhomogeneous Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) states. The neutrino emissivity and specific heat are obtained, from which the cooling rate is estimated.

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