共查询到20条相似文献,搜索用时 15 毫秒
1.
José Carlos N. de Araujo Guilherme F. Marranghello 《General Relativity and Gravitation》2009,41(6):1389-1406
We study the generation of a stochastic gravitational wave (GW) background produced by a population of neutron stars (NSs)
which go over a hadron-quark phase transition in its inner shells. We obtain, for example, that the NS phase transition, in
cold dark matter scenarios, could generate a stochastic GW background with a maximum amplitude of h
BG ~ 10−24, in the frequency band ν
obs ≃ 20–2,000 Hz for stars forming at redshifts of up to z ≃ 20. We study the possibility of detection of this isotropic GW background by correlating signals of a pair of Advanced
LIGO observatories. 相似文献
2.
Alice K. Harding 《Frontiers of Physics》2013,8(6):679-692
Neutron stars are a very diverse population, both in their observational and their physical properties. They prefer to radiate most of their energy at X-ray and gamma-ray wavelengths. But whether their emission is powered by rotation, accretion, heat, magnetic fields or nuclear reactions, they are all different species of the same animal whose magnetic field evolution and interior composition remain a mystery. This article will broadly review the properties of inhabitants of the neutron star zoo, with emphasis on their high-energy emission. 相似文献
3.
M. Baldo E. E. Saperstein S. V. Tolokonnikov 《The European Physical Journal A - Hadrons and Nuclei》2007,32(1):97-108
A semi-microscopic self-consistent quantum approach developed recently to describe the inner-crust structure of neutron stars
within the Wigner-Seitz (WS) method with the explicit inclusion of neutron and proton pairing correlations is further developed.
In this approach, the generalized energy functional is used which contains the anomalous term describing the pairing. It is
constructed by matching the realistic phenomenological functional by Fayans et al. for describing the nuclear-type cluster in the center of the WS cell with the one calculated microscopically for neutron
matter. Previously, the anomalous part of the latter was calculated within the BCS approximation. In this work corrections
to the BCS theory which are known from the many-body theory of pairing in neutron matter are included into the energy functional
in an approximate way. These modifications have a sizable influence on the equilibrium configuration of the inner crust, i.e. on the proton charge Z and the radius R
c of the WS cell. The effects are quite significant in the region where the neutron pairing gap is larger. 相似文献
4.
The eigen frequencies of radial pulsations of neutron stars are calculated in a strong magnetic field. At low densities we
use the magnetic BPS equation of state (EOS) similar to that obtained by Lai and Shapiro while at high densities the EOS obtained
from the relativistic nuclear mean field theory is taken and extended to include strong magnetic field. It is found that magnetized
neutron stars support higher maximum mass whereas the effect of magnetic field on radial stability for observed neutron star
masses is minimal. 相似文献
5.
By making use of Duan--Ge's decomposition theory of gauge potential
and the topological current theory proposed by Prof. Duan
Yi-Shi, we study a two-component superfluid Bose condensed system,
which is supposed to be realized in the interior of neutron stars in
the form of the coexistence of a neutron superfluid and a protonic
superconductor. We propose that this system possesses vortex lines.
The topological charges of the vortex lines are characterized by the
Hopf indices and the Brower degrees of φ-mapping. 相似文献
6.
The equation of state for neutron matter is calculated within relativistic Hartree–Fock approximation. The tensor couplings of vector mesons to baryons are included, and the change of baryon internal structure in matter is also considered using the quark–meson coupling model. We obtain the maximum neutron-star mass of ∼2.0M⊙, which is consistent with the recently observed, precise mass, 1.97±0.04M⊙. The Fock contribution is very important and, in particular, the inclusion of tensor coupling is vital to obtain such large mass. The baryon structure variation in matter also enhances the mass of a neutron star. 相似文献
7.
8.
We investigate the composition and structure of neutron-, hybrid-, and quark stars within an effective QCD-motivated model of strong interaction. The hadronic phase is described within a novel chiral SU(3) model and the deconfined quark-gluon plasma phase is formulated within the bag model. The phase transition between these phases is treated as a first order transition having two conserved charges. 相似文献
9.
Resonant nuclear reaction ~(23)Mg(p,γ) ~(24)Al in strongly screening magnetized neutron star crust 下载免费PDF全文
Based on the relativistic theory of superstrong magnetic fields(SMF), by using three models those of Lai(LD), Fushiki(FGP), and our own(LJ), we investigate the influence of SMFs due to strong electron screening(SES) on the nuclear reaction ~(23)Mg(p,γ) ~(24)Al in magnetars. In a relatively low density environment(e.g., ρ_7 0.01)and 1 B_(12) 10~2, our screening rates are in good agreement with those of LD and FGP. However, in relatively high magnetic fields(e.g., B_(12) 10~2), our reaction rates can be 1.58 times and about three orders of magnitude larger than those of FGP and LD, respectively(B_(12), ρ~7 are in units of 10~(12)G, 10~7 g cm~(-3)). The significant increase of strong screening rate can imply that more ~(23)Mg will escape from the Ne-Na cycle due to SES in a SMF. As a consequence,the next reaction, ~(24)Al(+β, ν) ~(24)Mg, will produce more ~(24)Mg to participate in the Mg-Al cycle. Thus, it may lead to synthesis of a large amount of A20 nuclides in magnetars. 相似文献
10.
Whether or not the deconfined quark phase exists in neutron star cores is an open question. We use two realistic effective
quark models, the three-flavor Nambu-Jona-Lasinio model and the modified quark-meson coupling model, to describe the neutron
star matter. We show that the modified quark-meson coupling model, which is fixed by reproducing the saturation properties
of nuclear matter, can be consistent with the experimental constraints from nuclear collisions. After constructing possible
hybrid equations of state (EOSes) with an unpaired or color superconducting quark phase with the assumption of the sharp hadron-quark
phase transition, we discuss the observational constraints from neutron stars on the EOSes. It is found that the neutron star
with pure quark matter core is unstable and the hadronic phase with hyperons is denied, while hybrid EOSes with a two-flavor
color superconducting phase or unpaired quark matter phase are both allowed by the tight and most reliable constraints from
two stars Ter 5 I and EXO 0748-676. And the hybrid EOS with an unpaired quark matter phase is allowed even compared with the
tightest constraint from the most massive pulsar star PSR J0751+1807. 相似文献
11.
陈晏军 《中国物理C(英文版)》2019,43(3):035101-035101-1
An extended Nambu-Jona-Lasinio(eNJL) model with nucleons as the degrees of freedom is used to investigate properties of nuclear matter and neutron stars(NSs),including the binding energy and symmetry energy of the nuclear matter, the core-crust transition density, and mass-radius relation of NSs. The fourth-order symmetry energy at saturation density is also investigated. When the bulk properties of nuclear matter at saturation density are used to determine the model parameters, the double solutions of parameters are obtained for a given nuclear incompressibility. It is shown that the isovector-vector interaction has a significant influence on the nuclear matter and NS properties, and the sign of isovector-vector coupling constant is critical in the determination of the trend of the symmetry energy and equation of state. The effects of the other model parameters and symmetry energy slope at saturation density are discussed. 相似文献
12.
Joachim E. Trümper 《Progress in Particle and Nuclear Physics》2011,66(3):674-680
We summarize the constraints on the equation of state of high-density nuclear matter derived from neutron star observations. The most stringent constraints are provided by the largest mass, the largest radius, the highest rotational frequency, and the maximum surface gravity observed for neutron stars. The combination of these constraints allows only nuclear equations of state which are quite stiff. 相似文献
13.
We investigate the role of Bose-Einstein condensation (BEC) of anti-kaons on the equation of state (EoS) and other properties
of compact stars. In the framework of relativistic mean field model we determine the EoS for β-stable hyperon matter and compare it to the situation when anti-kaons condense in the system. We observe that anti-kaon condensates
soften the EoS, thereby lowering the maximum mass of the stars. We also demonstrate that the presence of antikaon condensates
in the high density core of compact stars may lead to a new mass sequence beyond white dwarf and neutron stars. The limiting
mass of the new sequence stars is nearly equal to that of neutron star branch though they have distinctly different radii
and compositions. They are called neutron star twins. 相似文献
14.
Information theoretical methods as discerning quantifiers of the equations of state of neutron stars
In this work we use the statistical measures of information entropy, disequilibrium and complexity to discriminate different approaches and parametrizations for different equations of state for quark stars. We confirm the usefulness of such quantities to quantify the role of interactions in such stars. We find that within this approach, a quark matter equation of state such as SU(2) NJL with vectorial coupling and phase transition is slightly favoured and deserves deeper studies. 相似文献
15.
Klaas Vantournhout Thomas NeffHans Feldmeier Natalie JachowiczJan Ryckebusch 《Progress in Particle and Nuclear Physics》2011,66(2):271-275
We present a novel method to study the dynamics of bulk fermion systems such as the neutron star’s crust. By introducing periodic boundary conditions into Fermionic Molecular Dynamics, it becomes possible to examine the long-range many-body correlations induced by antisymmetrisation in bulk fermion systems. The presented technique treats the spins and the fermionic nature of the nucleons explicitly and permits investigating the dynamics of the system. Despite the increased complexity related to the periodic boundary conditions, the proposed formalism remains computationally feasible. 相似文献
16.
H. Schatz 《Progress in Particle and Nuclear Physics》2011,66(2):277-282
This paper provides an introduction to the role that the physics of rare isotopes plays in the interpretation of observations of accreting neutron stars. 相似文献
17.
The rates of axion emission by nucleon–nucleon bremsstrahlung are calculated with the inclusion of the full momentum contribution from a nuclear one pion exchange (OPE) potential. The contributions of the neutron–neutron (nn), proton–proton ( pp) and neutron–proton (np) processes in both the non-degenerate and degenerate limits are explicitly given. We find that the finite-momentum corrections to the emissivities are quantitatively significant for the non-degenerate regime and temperature-dependent, and should affect the existing axion mass bounds. The trend of these nuclear effects is to diminish the emissivities. 相似文献
18.
C. Y. Ryu C. H. Hyun S. W. Hong B. K. Jennings 《The European Physical Journal A - Hadrons and Nuclei》2005,24(1):149-157
We investigate the properties of the neutron star with relativistic mean-field models. We incorporate in the quantum hadrodynamics and in the quark-meson coupling models a possible reduction of meson masses in nuclear matter. The equation of state for neutron star matter is obtained and is employed in Oppenheimer-Volkov equation to extract the maximum mass of the stable neutron star. We find that the equation of state, the composition and the properties of the neutron stars are sensitive to the values of the meson masses in medium. 相似文献
19.
In a series of papers it was discussed,on the basis of phenomenological arguments, whether the high frequency quasiperiodic
oscillations (kHz QPOs)observed in the neutron-star and black-hole X-ray sources originate in the same physical mechanism.
Recently it was suggested that a general trend seen in neutron star kHz QPOs instead excludes such a uniform origin. Using
the example of the atoll source 4U 1636-53 we illustrate that this is not neccesarily true.
相似文献
20.
The role of hypernuclear physics for the physics of neutron stars is delineated. Hypernuclear potentials in dense matter control the hyperon composition of dense neutron star matter. The three-body interactions of nucleons and hyperons determine the stiffness of the neutron star equation of state and thereby the maximum neutron star mass. Two-body hyperon–nucleon and hyperon–hyperon interactions give rise to hyperon pairing which exponentially suppresses cooling of neutron stars via the direct hyperon URCA processes. Nonmesonic weak reactions with hyperons in dense neutron star matter govern the gravitational wave emissions due to the r-mode instability of rotating neutron stars. 相似文献