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1.
The state of super-dense matter is essential for us to understand the nature of pulsars; however, non- perturbative quantum chromodynamics makes it very difficult to make direct calculations of the state of cold matter at realistic baryon number densities inside compact stars. Nevertheless, from an observational point of view, it is conjectured that pulsars could be made up of quark clusters since the strong coupling between quarks might render the quarks to be grouped in clusters. In this paper, we attempt to find an equation of state of condensed quark-cluster matter in a phenomenological way. Supposing that the quark-clusters could be analogized to inert gases, we apply here the corresponding-state approach to derive the equation of state of quark-cluster matter, as was similarly demonstrated for nuclear and neutron-star matter in the 1970s. According to the calculations that we have presented, the quark-cluster stars, which are composed of quark-cluster matter, could have a high maximum mass that is consistent with observations and, in turn, further observations of pulsar mass could also place a constraint on the properties of quark-cluster matter. We will also briefly discuss the melting heat during the solid-liquid phase conversion and its related astrophysical consequences. 相似文献
2.
Quarks are proposed to be grouped together to make quark-clusters due to the strong interaction in cold quark matter at a few nuclear densities, because a weakly coupling treatment of the interaction between quarks there would be inadequate. Cold quark matter is then conjectured to be in solid state (i.e., forming a crystal structure) if the inter-cluster potential is deep enough to localize clusters in lattice. Such a solid state of cold quark matter would be very necessary for us to understand different manifestations of pulsar-like compact stars, and could not be ruled by first principles. 相似文献
3.
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
4.
XNAV/UVNAV/SINS组合导航在航天器轨道机动中的应用 总被引:1,自引:0,他引:1
针对X射线脉冲星导航在航天器轨道机动过程中精度不高甚至发散的问题,提出一种将X射线脉冲星导航结合惯性导航和紫外敏感器的组合导航方法。以航天器在惯性系中的位置、速度、姿态四元数和惯性导航设备误差作为系统状态变量,用X射线探测器测量X射线脉冲到达时间,用紫外敏感器测量中心天体质心相对于航天器的方向矢量和距离以及航天器在惯性系中的姿态四元数,用扩展卡尔曼滤波器估计组合导航系统状态。仿真结果验证了该组合导航方法的可行性,能够解决轨道机动中X射线脉冲星单独导航的误差过大(位置误差达107m)问题,且该组合导航具有较高的导航精度,在轨道机动前、机动中和机动后导航位置误差均在100 m以内。 相似文献
5.
ZhiXuan Li KeJia Lee Ricardo Nicolaos Caballero YongHua Xu LongFei Hao Min Wang JianCheng Wang 《中国科学:物理学 力学 天文学(英文版)》2020,(1):112-117
In this paper,we investigate the statistical signal-processing algorithm to measure the instant local clock jump from the timing data of multiple pulsars.Our algorithm is based on the framework of Bayesian statistics.In order to make the Bayesian algorithm applicable with limited computational resources,we dedicated our efforts to the analytic marginalization of irrelevant parameters.We found that the widely used parameter for pulsar timing systematics,the"Efac"parameter,can be analytically marginalized.This reduces the Gaussian likelihood to a function very similar to the Student’s t-distribution.Our iterative method to solve the maximum likelihood estimator is also explained in the paper.Using pulsar timing data from the Yunnan Kunming 40-m radio telescope,we demonstrate the application of the method,where 80-ns level precision for the clock jump can be achieved.Such a precision is comparable to that of current commercial time transferring service using satellites.We expect that the current method could help developing the autonomous pulsar time scale. 相似文献
6.
7.
XU XiangYang WANG Chen HAN JinLin & HU Lin College of Science Guizhou University Guiyang China National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国科学:物理学 力学 天文学(英文版)》2011,(3)
Radio detection of pulsars in the Galactic disk is strongly affected by the dispersion and scattering effect of the interstellar medium and the Galactic background radio emission. In order to know the best conditions for discovery of pulsars, we select and simulate pulsar samples in the Galactic disk, and calculate the detection probability with various observation conditions (such as observational frequency, telescope aperture, receiver bandwidth and integration time). We have found that the detection frac... 相似文献
8.
In this paper we have studied the motion of charged particles in a dipole magnetic field on the Schwarzscbild background geometry.
A detailed analysis has been made in the equatorial plane through the study of the effective potential curves. In the case
of positive canonical angular momentum the effective potential has two maxima and two minima giving rise to a well-defined
potential well rear the event horizon. This feature of the effective potential categorises the particle orbits into four classes,
depending on their energies. (i) Particles, coming from infinity with energy less than the absolute maximum ofV
eff, would scatter away after being turned away by the magnetic field. (ii) Whereas those with energies higher than this would
go into the central star seeing no barrier. (iii) Particles initially located within the potential well are naturally trapped,
and they execute Larmor motion in bound gyrating orbits. (iv) and those with initial positions corresponding to the extrema
ofV
eff follow circular orbits which are stable for non-relativistic particles and unstable for relativistic ones. We have also considered
the case of negative canonical angular momentum and found that no trapping in bound orbits occur for this case.
In the case when particles are not confined to the equatorial plane we have found that the particles execute oscillatory motion
between two mirror points if the magnetic field is sufficiently high, but would continuously fall towards the event horizon
otherwise.
An erratum to this article is available at . 相似文献
9.
The dispersion relation of electromagnetic waves in the presence of magnetic monopoles of electron mass in a uniform magnetic
field is obtained. The waves of the frequencyω in the range ωϱi<Ωi<ω<Ω
e
<ωϱa are analysed. It is shown that the monopole charges lead to observable effects. Finally, the results are applied to a typical
pulsar. 相似文献
10.
Einsteins equivalence principle has a number of problems, and it is often applied incorrectly. Clocks on the earth do not seem to be affected by the suns gravitational potential. The most commonly accepted reason given is a faulty application of the equivalence principle. While no valid reason is available within either the special or general theories of relativity, ether theories can provide a valid explanation. A clock bias of the correct magnitude and position dependence can convert the Selleri transformation of ether theories into an apparent Lorentz transformation, which gives rise to an apparent equivalence of inertial frames. The results indicate that the special theory is invalid and that only an apparent relativity exists. 相似文献