排序方式: 共有23条查询结果,搜索用时 15 毫秒
1.
WANG Bo LIU ZhengWei HAN YunKun LEI ZhenXin LUO YangPing & HAN ZhanWen National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming China Key Laboratory for the Structure Evolution of Celestial Objects Graduate University of Chinese Academy of Sciences Beijing 《中国科学:物理学 力学 天文学(英文版)》2010,(3)
Type Ia supernovae (SNe Ia) play an important role in diverse areas of astrophysics, from the chemical evolution of galaxies to observational cosmology. However, the nature of the progenitors of SNe Ia is still unclear. In this paper, according to a detailed binary population synthesis study, we obtained SN Ia birthrates and delay times from different progenitor models, and compared them with observations. We find that the Galactic SN Ia birthrate from the double-degenerate (DD) model is close to those infe... 相似文献
2.
Dörte Hansen 《General Relativity and Gravitation》2006,38(7):1173-1208
An approximate strategy for studying the evolution of binary systems of extended objects is introduced. The stars are assumed to be polytropic ellipsoids. The surfaces of constant density maintain their ellipsoidal shape during the time evolution. The equations of hydrodynamics then reduce to a system of ordinary differential equations for the internal velocities, the principal axes of the stars and the orbital parameters. The equations of motion are given within Lagrangian and Hamiltonian formalism. The special case when both stars are axially symmetric fluid configurations is considered. Leading order gravitational radiation reaction is incorporated, where the quasi-static approximation is applied to the internal degrees of freedom of the stars. The influence of the stellar parameters, in particular the influence of the polytropic index n, on the leading order gravitational waveforms is studied. 相似文献
3.
Simone Mastrogiovanni Christos Karathanasis Jonathan Gair Gregory Ashton Stefano Rinaldi Hsiang-Yu Huang Gergely Dálya 《Annalen der Physik》2024,536(2):2200180
Standard sirens have been the central paradigm in gravitational-wave cosmology so far. From the gravitational wave signature of compact star binaries, it is possible to measure the luminosity distance of the source directly, and if additional information on the source redshift is provided, a measurement of the cosmological expansion can be performed. This review article discusses several methodologies that have been proposed to use gravitational waves for cosmological studies. Methods that use only gravitational-wave signals and methods that use gravitational waves in conjunction with additional observations such as electromagnetic counterparts and galaxy catalogs will be discussed. The review also discusses the most recent results on gravitational-wave cosmology, starting from the binary neutron star merger GW170817 and its electromagnetic counterpart and finishing with the population of binary black holes, observed with the third Gravitational-wave Transient Catalog GWTC–3. 相似文献
4.
There are spin-orbit interaction and spin-spin interaction in a generic post-Newtonian Lagrangian formu-lation of comparable mass spinning compact binaries. The spin-orbit coupling or the spin-spin coupling plays a quite important role in changing the evolution of the system and may sometime cause chaotic behavior. How do the two types of couplings exert together any influences on chaos in this formulation? To answer it, we simply take the Lagrangian formulation of a special binary system, including the Newtonian term and the leading-order spin-orbit and spin-spin couplings. The key to this question can be found from a Hamiltonian formulation that is completely identical to the Lagrangian formulation. If the Lagrangian does not include the spin-spin coupling, its equivalent Hamiltonian has an additional term (i.e. the next-order spin-spin coupling) as well as those terms of the Lagrangian. The spin-spin coupling rather than the spin-orbit coupling makes the Hamiltonian typically nonintegrable and probably chaotic when two objects spin. When the leading-order spin-spin coupling is also added to the Lagrangian, it still appears in the Hamiltonian. In this sense, the total Hamiltonian contains the leading-order spin-spin coupling and the next-order spin-spin coupling, which have different signs. Therefore, the chaos resulting from the spin-spin interaction in the Legrangian formulations is somewhat weakened by the spin-orbit coupling. 相似文献
5.
潮汐效应是影响恒星结构和演化非常重要的物理因素.本文研究了影响潮汐同步和轨道圆化的物理因素,如恒星质量、初始转速、轨道周期、金属丰度、对流超射等,并根据转动恒星的角动量转移和元素扩散方程,给出了这些因素对转动双星演化和元素混合的影响.结果表明:具有大质量子星、初始转速慢、对流超射小、轨道周期短的双星系统,能更早地达到平衡速度和轨道圆化;初始转速快的恒星,由于潮汐同步过程减速,双星系统中氮元素增丰没有单星的氮元素增丰显著;大质量星、高金属丰度、超射大和短周期的双星系统,氮增丰相对显著;质量小、金属丰度低、转速慢、超射大的恒星具有较小的恒星半径,而低金属丰度恒星表面却具有较高的有效温度,快速转动单星向低温和低光度端演化. 相似文献
6.
In this paper we deal with the measurement of parameters of the gravitational wave signal emitted by a coalescing binary system
of compact stars. We present the results of Monte Carlo simulations carried out for initial LIGO, incorporating the first
post-Newtonian corrections to the waveform. Using the parameters so determined, we estimate the direction to the source. We
stress the use of the time-of-coalescence rather than the time-of-arrival of the signal to determine the direction of the
source. We show that this can considerably reduce the errors in the determination of the direction of the source. 相似文献
7.
Wu Xue-bing 《Frontiers of Physics in China》2006,1(2):135-142
The determination of the mass of black holes in our universe is crucial to understand their physics nature but is a great
challenge to scientists. In this paper I briefly review some methods that are currently used to estimate the mass of black
holes, especially those in X-ray binary systems and in galactic nuclei. Our recent progress in improving the mass estimates
of supermassive black holes in active galactic nuclei by involving some empirical relations is presented. Finally I point
out the similarities and common physics in Galactic black hole X-ray binaries and active galactic nuclei, and demonstrate
that the black hole mass estimation is very much helpful to understand the accretion physics around black holes. 相似文献
8.
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
9.
During the evolution of the binary system,many physical processes occur,which can influence the orbital angular velocity and the spin angular velocities of the two components,and influence the non-synchronous or synchronous rotation of the system.These processes include the transfer of masses and angular momentums between the component stars,the loss of mass and angular momentum via stellar winds,and the deformation of the structure of component stars.A study of these processes indicates that they are closely related to the combined effects of tide and rotation.This means,to study the synchronous or non-synchronous rotation of binary systems,one has to consider the contributions of different physical processes simultaneously,instead of the tidal effect alone.A way to know whether the rotation of a binary system is synchronous or non-synchronous is to calculate the orbital angular velocity and the spin angular velocities of the component stars.If all of these angular velocities are equal,the rotation of the system is synchronous.If not,the rotation of the system is non-synchronous.For this aim,a series of equations are developed to calculate the orbital and spin angular velocities.The evolutionary calculation of a binary system with masses of 10M⊙+6M⊙shows that the transfer of masses and angular momentums between the two components,and the deformation of the components structure in the semidetached or in the contact phase can change the rotation of the system from synchronous into non-synchronous rotation. 相似文献
10.
B S Sathyaprakash 《Pramana》2001,56(4):457-475
The new millennium will see the upcoming of several ground-based interferometric gravitational wave antennas. Within the next
decade a space-based antenna may also begin to observe the distant Universe. These gravitational wave detectors will together
operate as a network taking data continuously for several years, watching the transient and continuous phenomena occurring
in the deep cores of astronomical objects and dense environs of the early Universe where gravity was extremely strong and
highly nonlinear. The network will listen to the waves from rapidly spinning non-axisymmetric neutron stars, normal modes
of black holes, binary black hole inspiral and merger, phase transitions in the early Universe, quantum fluctuations resulting
in a characteristic background in the early Universe. The gravitational wave antennas will open a new window to observe the
dark Universe unreachable via other channels of astronomical observations. 相似文献