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1.
In this paper we calculate the number of close binaries formed during the evolution process of a globular cluster core. The globular cluster core is assumed to contain a massive black hole at its center. We show that the central black hole can drive binaries formation in the core and the rate of binaries formation depends on the mass of the black hole at its center. When the massM of the black hole is between 102
M
and 3×103
M
, there will be a few binaries formed. When the mass of the black hole is 4×103
M
M6×103
M
, the number of binary star formation will suddenly increase with a jump to the maximum value 58. When the mass of the black hole is 7×103
M
M9×103
M
, the number of binary star will immediately decrease. Whether cluster X-ray is produced mainly by the central black hole or by binaries in the core depends on the mass of the central black hole. Therefore, two cases arise: namely, black hole accretion domination and binaries radiation domination. We do think that we cannot exclude the possibility of the existence of a central black hole even when binary radiation characteristics have been observed in globular cluster X-ray sources. 相似文献
2.
In this paper we consider effects of the general relativity and an accreting black hole in a globular cluster by studying the evolution of a globular cluster core as a whole, i.e., without the partition of the core into the so-called cusp and isothermal core regions. The globular cluster core is assumed to contain a massive black hole at its center. We show that the final fate of the evolution of a globular cluster core depends on the mass of the black hole at its center. When the massM of the black hole is greater than 3×103
M
, there will be a contraction of the core. On the other hand, if the mass of the black hole is smaller (102
M
M3×103
M
) in the center, the core will expand until complete dissolution. 相似文献
3.
Ramesh Chander Kapoor 《Astrophysics and Space Science》1985,112(2):347-359
We have used the impulsive approximation technique to numerically estimate the effect of dynamical friction on the motion of a supermassive black hole (mass 109
M
) through a galaxy (mass=1011
M
) which has recoiled from the center of the latter as a result of anisotropic emission of gravitational radiation or asymmetric plasma emission. We find the effect to be minimal for recoil taking place at a velocity larger than that of escape at the center of the galaxy. There is a certain critical velocity of ejection (slightly larger than the central escape velocity) at which the black hole must be ejected for the recoil to be successful. Otherwise, dynamical friction becomes relatively pronounced and damped oscillatory motion of the black hole in the potential well of the galaxy ensues. The phenomenon of high-velocity recoil although rare, can be astrophysically spectacular in view of the fact that the black hole would carry a substantial amount of gaseous material as well as a very large number of galactic stars. Some recent observations are cited where the recoil phenomenon might be applicable. 相似文献
4.
A. P. Trofimenko 《Astrophysics and Space Science》1990,168(2):277-292
Possible manifestations of small mass black holes (M
BH<M
) in cosmic bodies (stars, millisecond pulsars, planets, etc.) are considered. The formation of millisecond pulsars in the early proposed pulsar's model goes onto a small black hole in the centre due to accretion of neutron star matter. Within the framework of a model under consideration, the following is predicted: millisecond pulsars withP
min=0.5 ms, single optical and X-ray pulsars with the negative derivative derivative of period. Small black holes can be applied to make models of anomalies in planetary bodies (gravitational, heat, etc.). The vulcan model with radiation of a microblack hole in a magnetic void (M
BH1015 g) as the source of energy is considered. At the Earth's surface, near a vulcan, the neutrino flow from a microblack hole is estimated. 相似文献
5.
Z. Horák 《Astrophysics and Space Science》1982,86(2):471-476
In 1979 I developed a special-relativistic analysis explaining the discrepancy of observed redshifts of spiral NGC 4319 and its companion quasar Markarian 205 by considering besides the Lorentz time dilatation also the gravitational redshift due to the gravitational field of Markarian 205 interpreted in terms of accretion of mass onto a black hole ejected from NGC 4319. In the present paper, a general-relativistic analysis is given. Numerical results of the special and general theories do not differ from each other significantly and admit the conclusion that the radius,r, of the radiating region of Markarian 205 is of the order of the tidal radius of black hole. Several models for various values of the ratio ofr to the Schwarzschild radius,r
s, are constructed. Models with 8.5r/r
s8.7 seem to be most realistic. It becomes clear that the interpretation of quasars in terms of huge black holes accreting stars can explain, in principle, the observed redshifts of quasars ejected from parent galaxies. 相似文献
6.
J. Schmid-Burgk 《Astrophysics and Space Science》1978,56(1):191-218
To extend Shapiro's (1973a, b) calculations of black hole accretion to the regimes of interstellar gas densities and of black hole masses for which emergent luminosities are expected to be high, the radiation hydrodynamics of spherically symmetric gas flows in static isotropic metrics is discussed. Since for the more luminous objects the optical depth of the accretion volume becomes large, particular attention has to be paid to radiative transfer through non-Euclidean spaces, and a method for solving the full transfer problem is presented. The method is applied to accretion into black holes of mass between 10M
and 105
M
, under the conservative assumption that all other heat sources, like dissipation of magnetic or turbulent energy, can be neglected in comparison to the compressional work term,p dV. In the interstellar gas parameter range of interest, the radiation field is then dominated by emission and absorption of synchrotron radiation from inner zones of the flow. Temperature stratifications, luminosities and emergent spectra resulting from these processes are calculated. 相似文献
7.
Yong-Zhen Liu Zu-Gan Deng You-Yuan Zhou Jie-Hao Huang 《Astrophysics and Space Science》1986,123(1):137-144
With the aid of a simple black hole model of quasars we have found that the majority of the distinguishable emission lines in the spectrum of the quasar 1604+179 can be assigned to two redshift systems,z
r
=3.712 andz
b
=2.701. The appearance of double emission redshifts means that this quasar might be a massive black hole (of mass 108
M
M1011
M
) with a ring-like emission line region (of radius 1 light-day r
01 light-year) in its accretion disk. 相似文献
8.
The stationary two-dimensional magnetohydrodynamic solution for the accretion of the matter without pressure into a gravitating centre of a black hole is obtained. It is assumed that the magnetic field far from the collapsed star is homogeneous and its influence on the flow is negligible. Around the star, at the plane perpendicular to the direction of the magnetic field, the dense quasistationary disc is formed, the structure of which in a large extent is determined by dissipation processes. The structure is calculated for (a) a laminar disc with the Coulomb mechanism of dissipation; and (b) a turbulent disc.The estimations of the parameters of the shock which result from the infall of the matter onto the disc are given. In the last section the numerical estimation and approximate character of the radiation spectrum of the disc and the shock are obtained for two cases of 10M
and 105
M
. The luminosity of collapsed objects withM=10M
appears to be about solar, thus its observation is possibly only at the distances less than 300–1000 pc. The collapsed objects in the Galaxy withM=105
M
could constitute very bright sources in spectral regions from optical up to X-ray. The spectra of a laminar and a turbulent disc for 10M
black hole are very different. The laminar disc radiates primarily in the ultraviolet. The turbulent disc radiates a large part of its flux in the infrared. Therefore, one cannot exclude the possibility that some of the galactic infrared star-like sources are individual black holes in the accretion state. 相似文献
9.
In this paper we adopt the method of relativistic fluid dynamics to examine the number density distribution of stars around a massive black hole in the core of stellar clusters. We obtain extensive results,n(r) r
–a, 3/2a9/2, which include, respectively, then(r) r
–7/4 power law obtained by Bahcall and Wolf and then(r) r
–9/4 power law by Peebles. Sincen(r) is not an observable quantity for star clusters, we also consider general relativity effects, i.e., the consequence of the bending of light, in calculating the projected density of stars in such a system. As an example we employ a massive black hole 103
M
inlaid in the center of a globular cluster and calculate various projected densities of stars. The results show that cusp construction occurs in all cases unless the central black hole massM=0, and the polytropic index does not affect at all the position of the capture radiusr
a. The obvious differences in the surface density is only embodied in the interior of the capture radius. At the outer regions of the core, the surface density of stars declines rapidly with ar
–5 power law in all cases. These results can be applied to cases of unequal-mass and non-steady state. 相似文献
10.
Shuichi Tamazawa Kiyotaka Toyama Noboru Kaneko Yôrô Ôno 《Astrophysics and Space Science》1975,32(2):403-421
Spherically symmetric, steady-state, optically thick accretion onto a nonrotating black hole with the mass of
is studied. The gas accreting onto the black hole is assumed to be a fully ionized hydrogen plasma withn
0=108 cm–3 andT
0=104 K far from the black hole, and a new approximate expression for the Eddington factor is introduced. The luminosity is estimated to beL=1.875×1033 erg s–1, which primarily arises from the optical surface (1) ofT104 K. The accretion flow is characterized by 1 and (v/c)10. In the optically thin region, the flow remains isothermal, and the increase of temperature occurs at 1. The radiative equilibrium is strictly realized at (v/c)10. 相似文献
11.
Ralph P. Lano 《Astrophysics and Space Science》1989,159(1):125-132
The influence of a Schwarzschild black hole on the light from stars is examined. The result is, that due to gravitational lensing light comes from the black hole and thus a black hole shines. The effect is very small and numerical calculations suggest that the magnitude of the black hole is smaller than 60
m
, this means unobservable with present instruments. It is also shown that there is no effect on the cosmic background radiation. 相似文献
12.
This paper studies the properties of self-gravity of accretion discs around supermassive black holes. With integration on the thin disc configuration, this paper has calculated the radial and vertical components of self-gravity of accretion discs. The discussion mainly concentrates on the radial component, and the results are briefly as follows: for accretion discs around supermassive black holes (M10
8–1010 M). At the distance where (R/R
g)105–104, the radial component of self-gravity dominates over the central one where the dynamical structure of the accretion discs completely differs from that of Keplerian disc. A turbulence driven by radial self-gravity instability as a kind of energy source is proposed. This paper has two criteria for the comparison of magnitude between the self-gravity of accretion discs and the gravity of the central black hole, from which an analytic estimation for the outer radius of the accretion discs has been derived. The results of this paper may be used to explain the accretion discs of quasars and AGNs.This research was supported by the National Natural Science Foundation of China. 相似文献
13.
We consider the possibility of detecting intermediate-mass (103–104 M ⊙) black holes, whose existence at the centers of globular clusters is expected from optical and infrared observations, using precise pulse arrival timing for the millisecond pulsars in globular clusters known to date. For some of these pulsars closest to the cluster centers, we have calculated the expected delay times of pulses as they pass in the gravitational field of the central black hole. The detection of such a time delay by currently available instruments for the known pulsars is shown to be impossible at a black hole mass of 103 M ⊙ and very problematic at a black hole mass of 104 M ⊙. In addition, the signal delay will have a negligible effect on the pulsar periods and their first derivatives compared to the current accuracy of their measurements. 相似文献
14.
D. S. Davis 《Astrophysics and Space Science》1985,116(1):89-96
Spherical accretion onto black holes at high accretion rates leads to temperatures and optical depths for which Comptonization of the emerging radiation plays an important role, altering both the plasma temperature and the emergent spectrum. In this paper the nonlocal effects of Comptonization are accounted for by numerically modeling the scattering process with Monte Carlo techniques. Calculations are performed for black hole masses ranging from 101–109
M
and are compared with the local scattering model of Ipser and Price (1983). It is found that the local scattering approximation underestimates the energy in the X-ray portion of the spectrum. Monte Carlo calculations shows that the spectrum flattens and the spectral index decreases to values about 20% below those obtained by using the local scattering approximation. 相似文献
15.
J. H. Fan 《Astrophysics and Space Science》1995,229(1):157-162
In this paper, accretion disc and synchrotron emission models have been used to analyse simultaneous IR-optical-UV data of the BL Lac object 1727+502. In the following, some of its properties have been discussed. It is shown that the temperature of the disc is about 19, 000°k, the mass of the central black hole isM
8 5.4, and the accretion ratio is 10–3
M
/yr. 相似文献
16.
Ramesh Chander Kapoor 《Astrophysics and Space Science》1985,117(2):363-373
A numerical study has been made of the motion of a compact object consisting of a supermassive black hole with a dense cluster of stars around through a galaxy which has recoiled from the center of the latter as a result of anisotropic emission of gravitational radiation or asymmetrical plasma emission. We find that the effect of dynamical friction on its motion through the galaxy (mass1011
M
) estimated using the impulsive approximation technique, is minimal for an object mass 109
M
and for recoil taking place at a velocity larger than that of escape. A velocity 1.1 times the escape velocity is needed for the object to escape from the galaxy, whereas for velocities of recoil less than this critical velocity, damped oscillatory motion ensures. The energy exchange of the object with the galaxy is not large enough to cause appreciable change in the internal energy of the latter. 相似文献
17.
A model of the galactic centre with magnetic monopole has been presented here. The positron can be produced continuously through magnetic monopoles to induce baryon decay (Rubakov catalytic reaction) and a lot of energy can be released as well. The calculation results show that even if the galactic center contains only a few magnetic monopoles (=N
M/NB10–24), this massive object can not collapse into a black hole. This model can explain the observed intensities of the annihilation line and higher energy photons ofE
>511 keV from the galactic centre.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
18.
With the equations of neutrino heat conductivity being used, the neutrino light curve is calculated for the spherically symmetrical collapse of an iron-oxygen 2M
star (Figure 1) up to the formation of a hot hydrostatically equilibrium neutron star. The total energy, radiated in the form of muon and electron neutrinos, is 5.8×1053 erg (0.16Mc
2). The mean neutrino particle energy is 12 MeV for all the time the collapse proceeds. The maximum neutrino luminosity value is equal to 3×1053 erg s–1. For a 10M
star collapse, the luminosity maximum 3×1054 erg s–1 takes place just at the moment of the formation of a black hole inside the collapsing star. The total radiated energy in this case is about 0.08Mc
2. The set of calculations, allowing for the deposition of momentum by means of neutrino-nuclear coherent scattering, brings us to a conclusion that the envelope outburst is only possible if the scattering cross-section is 50 times larger than the value experimentally accepted (inequality 20)). 相似文献
19.
Simon F. Portegies Zwart Jasinta Dewi Tom Maccarone 《Astrophysics and Space Science》2005,300(1-3):247-253
The evolution of young (≲ 10 Myr) star clusters with a density exceeding about 105 star pc−3 are strongly affected by physical stellar collisions during their early lifetime. In such environments the same star may
participate in several tens to hundreds of collisions ultimately leading to the collapse of the star to a black hole of intermediate
mass. At later time, the black hole may acquire a companion star by tidal capture or by dynamical – three-body – capture.
When the captured star evolves it starts to fill its Roche-lobe and transfers mass to its accompanying black hole. This then
leads to a bright phase of X-ray emission, which lasts for the remaining main-sequence lifetime of the donor. If the star
captured by the intermediate mass black hole is relatively low mass ≲ 2 M⊙) the binary will also be visible as a bright source in gravitational waves. Based on empirical models we argue that, for
as long as the donor remains on the main sequence, the source will be ultraluminous Lx >rsim 1040 ergs-1 for about a week every few month. When the donor star is more massive >15 M⊙, or evolved off the main sequence the bright time is longer, but the total accretion phase lasts much shorter. 相似文献
20.
Small black holes which can be located in the Earth interior are proposed as sources of correlated short-time variation of gravitational field (gravitoimpulses) and-radiation in (-background variation) due to the Hawking effect. We estimate the intensity and spectrum of photon radiation for black holes with masses of 108–1016 g and consider possibility registration of them after absorption in terrestrial matter or in air in the correlation with gravitoimpulses. Restrictions of short-time gravitational field variation by means existing devices give possible range of black hole masses of the order of 1014 g which produce high penetrative-radiation with energies more than 100 MeV and detectable gravitoimpulses at distances several kilometers. 相似文献