scholarly journals Stable Up-Down Quark Matter Nuggets, Quark Star Crusts, and a New Family of White Dwarfs

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 70
Author(s):  
Lang Wang ◽  
Jian Hu ◽  
Cheng-Jun Xia ◽  
Jian-Feng Xu ◽  
Guang-Xiong Peng ◽  
...  
Keyword(s):  
Quark Matter ◽  
White Dwarfs ◽  
Maximum Mass ◽  
Quark Star ◽  
Small Surface ◽  
New Family ◽  
Quark Stars ◽  
Down Quark ◽  
The Stability ◽  
Chandrasekhar Limit

The possible existence of stable up-down quark matter (udQM) was recently proposed, and it was shown that the properties of udQM stars are consistent with various pulsar observations. In this work we investigate the stability of udQM nuggets and found at certain size those objects are more stable than others if a large symmetry energy and a small surface tension were adopted. In such cases, a crust made of udQM nuggets exists in quark stars. A new family of white dwarfs comprised entirely of udQM nuggets and electrons were also obtained, where the maximum mass approaches to the Chandrasekhar limit.

scholarly journals The most massive white dwarfs in the solar neighbourhood

2021 ◽  
Vol 503 (4) ◽  
pp. 5397-5408
Author(s):  
Mukremin Kilic ◽  
P Bergeron ◽  
Simon Blouin ◽  
A Bédard
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Transverse Velocity ◽  
Maximum Mass ◽  
Model Calculations ◽  
Rapid Rotation ◽  
Rotation Rates ◽  
Binary Mergers ◽  
Chandrasekhar Limit

ABSTRACT We present an analysis of the most massive white dwarf candidates in the Montreal White Dwarf Database 100 pc sample. We identify 25 objects that would be more massive than $1.3\, {\rm M}_{\odot }$ if they had pure H atmospheres and CO cores, including two outliers with unusually high photometric mass estimates near the Chandrasekhar limit. We provide follow-up spectroscopy of these two white dwarfs and show that they are indeed significantly below this limit. We expand our model calculations for CO core white dwarfs up to M = 1.334 M⊙, which corresponds to the high-density limit of our equation-of-state tables, ρ = 109 g cm−3. We find many objects close to this maximum mass of our CO core models. A significant fraction of ultramassive white dwarfs are predicted to form through binary mergers. Merger populations can reveal themselves through their kinematics, magnetism, or rapid rotation rates. We identify four outliers in transverse velocity, four likely magnetic white dwarfs (one of which is also an outlier in transverse velocity), and one with rapid rotation, indicating that at least 8 of the 25 ultramassive white dwarfs in our sample are likely merger products.

Quark matter in the perturbation QCD model with a rapidly convergent matching-invariant running coupling

2017 ◽  
Vol 26 (06) ◽  
pp. 1750034 ◽  
Author(s):  
Jian-Feng Xu ◽  
Yan-An Luo ◽  
Lei Li ◽  
Guang-Xiong Peng
Keyword(s):  
Perturbation Theory ◽  
Infinite Number ◽  
Quark Matter ◽  
Chemical Potential ◽  
Maximum Mass ◽  
Solar Mass ◽  
Quark Stars ◽  
Dense Quark Matter ◽  
Subtraction Point ◽  
Running Coupling

The properties of dense quark matter are investigated in the perturbation theory with a rapidly convergent matching-invariant running coupling. The fast convergence is mainly due to the resummation of an infinite number of known logarithmic terms in a compact form. The only parameter in this model, the ratio of the renormalization subtraction point to the chemical potential, is restricted to be about 2.64 according to the Witten–Bodmer conjecture, which gives the maximum mass and the biggest radius of quark stars to be, respectively, two times the solar mass and 11.7[Formula: see text]km.

scholarly journals QUARK STARS ADMITTING A ONE-PARAMETER GROUP OF CONFORMAL MOTIONS

2004 ◽  
Vol 13 (01) ◽  
pp. 149-156 ◽  
Author(s):  
M. K. MAK ◽  
T. HARKO
Keyword(s):  
Analytical Solution ◽  
Quark Matter ◽  
Spherical Symmetry ◽  
Total Mass ◽  
Strange Quark ◽  
Exact Analytical Solution ◽  
Quark Star ◽  
Parameter Group ◽  
Quark Stars

An exact analytical solution describing the interior of a charged strange quark star is found under the assumption of spherical symmetry and the existence of a one-parameter group of conformal motions. The solution describes a unique static charged configuration of quark matter with radius R=9.46 km and total mass M=2.86M⊙.

scholarly journals Quark star matter at finite temperature in a quasiparticle model

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Peng-Cheng Chu ◽  
Yao-Yao Jiang ◽  
He Liu ◽  
Zhen Zhang ◽  
Xiao-Min Zhang ◽  
...  
Keyword(s):  
Quark Matter ◽  
Strange Quark ◽  
Large Mass ◽  
Compact Stars ◽  
Heating Process ◽  
Maximum Mass ◽  
Quark Stars ◽  
Star Evolution ◽  
Quasiparticle Model ◽  
Effects Of Temperature

AbstractWe study the thermodynamic properties of asymmetric quark matter, large mass quark stars (QSs), and proto-quark stars (PQSs) within the quasiparticle model. Considering the effects of temperature within quasiparticle model can significantly influence the EOS and the entropy of strange quark matter (SQM), quark fractions in SQM, as well as the tidal deformability and the maximum mass of PQSs along the star evolution line. Our results indicate that the recent discovered heavy compact stars PSR J0348+0432, MSR J0740+6620, PSR J2215+5135, and especially the GW190814’s secondary component $$m_2$$ m 2 can be well described as QSs within the quasiparticle model. The tidal deformability for the QSs describing the heavy compact stars is extremely large, which can not well describe GW170817 as QSs, and the effects of the temperature in the heating process along the star evolution will further increase the tidal deformability and the maximum mass of PQSs.

On the stability of two-flavor and three-flavor quark matter in quark stars within the framework of NJL model

2020 ◽  
Vol 35 (39) ◽  
pp. 2050321 ◽  
Author(s):  
Qianyi Wang ◽  
Tong Zhao ◽  
Hongshi Zong
Keyword(s):  
Quark Matter ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Chiral Phase ◽  
Quark Stars ◽  
Njl Model ◽  
The Stability ◽  
Chiral Susceptibility ◽  
Strong Interaction Matter

Following our recently proposed self-consistent mean field approximation approach, we have done some researches on the chiral phase transition of strong interaction matter within the framework of Nambu-Jona-Lasinio (NJL) model. The chiral susceptibility and equation of state (EOS) are computed in this work for both two-flavor and three-flavor quark matter for contrast. The Pauli–Villars scheme, which can preserve gauge invariance, is used in this paper. Moreover, whether the three-flavor quark matter is more stable than the two-flavor quark matter or not in quark stars is discussed in this work. In our model, when the bag constant are the same, the two-flavor quark matter has a higher pressure than the three-flavor quark matter, which is different from what Witten proposed in his pioneering work.

scholarly journals MASS–RADIUS RELATION FOR MAGNETIZED STRANGE QUARKS STARS

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1511-1519 ◽  
Author(s):  
A. P. MARTÍNEZ ◽  
R. G. FELIPE ◽  
D. M. PARET
Keyword(s):  
Magnetic Field ◽  
Quark Matter ◽  
Strange Quark ◽  
Baryon Density ◽  
Strange Quark Matter ◽  
Strange Quarks ◽  
Quark Stars ◽  
Mit Bag Model ◽  
The Stability ◽  
The Magnetic Field

We review the stability of magnetized strange quark matter (MSQM) within the phenomenological MIT bag model, taking into account the variation of the relevant input parameters, namely, the strange quark mass, baryon density, magnetic field and bag parameter. A comparison with magnetized asymmetric quark matter in β-equilibrium as well as with strange quark matter (SQM) is presented. We obtain that the energy per baryon for MSQM decreases as the magnetic field increases, and its minimum value at vanishing pressure is lower than the value found for SQM, which implies that MSQM is more stable than non-magnetized SQM. The mass–radius relation for magnetized strange quark stars is also obtained in this framework.

scholarly journals Quark star matter in heavy quark stars

2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Peng-Cheng Chu ◽  
Yi Zhou ◽  
Yao-Yao Jiang ◽  
Hong-Yang Ma ◽  
He Liu ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Quark Matter ◽  
Quark Mass ◽  
Orientation Distribution ◽  
Large Mass ◽  
Compact Stars ◽  
Credibility Interval ◽  
Quark Star ◽  
Mass Model ◽  
Quark Stars

AbstractWe study the thermodynamic properties of asymmetric quark matter and large mass quark stars within the confined-isospin-density-dependent-quark-mass model. We find that the quark matter symmetry energy should be very large in order to describe the recent discovered heavy compact stars PSR J0348+0432 ($$\text {2.01}\pm \text {0.04}M_{\odot }$$ 2.01 ± 0.04 M ⊙ ), MSP J0740+6620 ($$\text {2.14}\pm ^\text {0.10}_\text {0.09}M_{\odot }$$ 2.14 ± 0.09 0.10 M ⊙ of 68.3$$\%$$ % credibility interval and $$\text {2.14}\pm ^\text {0.20}_\text {0.18}M_{\odot }$$ 2.14 ± 0.18 0.20 M ⊙ of 95.4$$\%$$ % credibility interval) and PSR J2215+5135 (2.27$$\pm ^\text {0.10}_\text {0.09}M_{\odot }$$ ± 0.09 0.10 M ⊙ ) as QSs. The tidal deformability $$\Lambda _{1.4}$$ Λ 1.4 of the QSs is also investigated in this work, and the result indicates that $$\Lambda _{1.4}$$ Λ 1.4 may depend on the isospin effects and the strength / orientation distribution of the magnetic fields inside the quark stars.

scholarly journals MASS OF HIGHLY MAGNETIZED WHITE DWARFS EXCEEDING THE CHANDRASEKHAR LIMIT: AN ANALYTICAL VIEW

2012 ◽  
Vol 27 (15) ◽  
pp. 1250084 ◽  
Author(s):  
ARITRA KUNDU ◽  
BANIBRATA MUKHOPADHYAY
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Landau Level ◽  
White Dwarf ◽  
White Dwarfs ◽  
High Surface ◽  
Average Energy ◽  
The Stability ◽  
Chandrasekhar Limit ◽  
Very High

In recent years a number of white dwarfs have been observed with very high surface magnetic fields. We can expect that the magnetic field in the core of these stars would be much higher (~1014 G ). In this paper, we analytically study the effect of high magnetic field on relativistic cold electron, and hence its effect on the stability and the mass–radius relation of a magnetic white dwarf. In strong magnetic fields, the equation of state of the Fermi gas is modified and Landau quantization comes into play. For relatively very high magnetic fields (with respect to the average energy density of matter) the number of Landau levels is restricted to one or two. We analyze the equation of states for magnetized electron degenerate gas analytically and attempt to understand the conditions in which transitions from the zeroth Landau level to first Landau level occurs. We also find the effect of the strong magnetic field on the star collapsing to a white dwarf, and the mass–radius relation of the resulting star. We obtain an interesting theoretical result that it is possible to have white dwarfs with mass more than the mass set by Chandrasekhar limit.

scholarly journals ON THE MAXIMUM MASS AND MINIMUM ROTATION PERIOD OF RELATIVISTIC UNIFORMLY ROTATING WHITE DWARFS

2013 ◽  
Vol 23 ◽  
pp. 193-197
Author(s):  
KUANTAY BOSHKAYEV ◽  
JORGE RUEDA ◽  
REMO RUFFINI
Keyword(s):  
Chemical Composition ◽  
Equation Of State ◽  
White Dwarf ◽  
White Dwarfs ◽  
Rotation Period ◽  
Maximum Mass ◽  
Coulomb Interactions ◽  
General Relativistic ◽  
The Stability ◽  
Dynamical Instabilities

We investigate the stability of general relativistic uniformly rotating white dwarfs against secular and dynamical instabilities. We determine the minimum rotation period of stable white dwarfs depending on chemical composition of the white dwarf matter taking into account the Coulomb interactions as well as the nuclear interactions and the electroweak equilibrium at high densities, within the relativistic Feynman-Metropolis-Teller equation of state.

scholarly journals Reduction of the Mass of the Proto-Quark Star during Cooling

Particles ◽  
2021 ◽  
Vol 4 (1) ◽  
pp. 37-44
Author(s):  
Gevorg Hajyan
Keyword(s):  
Quark Matter ◽  
Finite Temperature ◽  
Supernova Explosion ◽  
Neutrino Emission ◽  
Quark Star ◽  
Bag Model ◽  
Quark Stars ◽  
Mit Bag Model

The integral parameters (mass, radius) of hot proto-quark stars that are formed in supernova explosion are studied. We use the MIT bag model to determine the pressure of up-down and strage quark matter at finite temperature and in the regime where neutrinos are trapped. It is shown that such stars are heated to temperatures of the order of tens of MeV. The maximum possible values of the central temperatures of these stars are determined. It is shown that the energy of neutrinos that are emitted from proto-quark stars is of the order of 250÷300 MeV. Once formed, the proto-quark stars cool by neutrino emission, which leads to a decrease in the mass of these stars by about 0.16–0.25 M⊙ for stars with the rest masses that are in the range Mb=1.22−1.62M⊙.

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