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1.
Gravitational waves from mergers of black holes and neutron stars are now being detected by LIGO. Here we look at a new source of gravitational waves, i.e., a class of dark matter objects whose properties were earlier elaborated. We show that the frequency of gravitational waves and strains on the detectors from such objects (including their mergers) could be within the sensitivity range of LIGO. The gravitational waves from the possible mergers of these dark matter objects will be different from those produced by neutron star mergers in the sense that they will not be accompanied by electromagnetic radiation since dark matter does not couple with radiation.
相似文献2.
V. I. Dokuchaev 《Astronomy Letters》2002,28(8):522-526
We discuss the possible observational manifestation of the formation of massive black holes in galactic nuclei in the form of an intense high-energy neutrino flux. A short-lived (≤10 yr) hidden neutrino source results from the natural dynamicalal evolution of a central star cluster in the galactic nucleus before its gravitational collapse. The central star cluster at the final evolutionary stage consists of degenerate compact stars (neutron stars and stellar-mass black holes) and is embedded in a massive gaseous envelope produced by destructive collisions of normal stars. Multiple fireballs from frequent collisions of neutron stars give rise to a tenuous quasi-stationary cavity in the central part of the massive envelope. The cavity is filled with shock waves on which an effective cosmic-ray acceleration takes place. Allthe accelerated particles, except the secondary high-energy neutrinos, are absorbed in the dense envelope. The neutrino signal that carries information on the dynamicals of the collapsing galactic nucleus can be recorded by a neutrino detector with an effective area S∼1 km2. 相似文献
3.
Guinevere Kauffmann Timothy M. Heckman 《Monthly notices of the Royal Astronomical Society》2009,397(1):135-147
We analyse the observed distribution of Eddington ratios ( L / L Edd ) as a function of supermassive black hole mass for a large sample of nearby galaxies drawn from the Sloan Digital Sky Survey. We demonstrate that there are two distinct regimes of black hole growth in nearby galaxies. The first is associated with galaxies with significant star formation [ M * /star formation rate (SFR) ∼ a Hubble time] in their central kiloparsec regions, and is characterized by a broad lognormal distribution of accretion rates peaked at a few per cent of the Eddington limit. In this regime, the Eddington ratio distribution is independent of the mass of the black hole and shows little dependence on the central stellar population of the galaxy. The second regime is associated with galaxies with old central stellar populations ( M * /SFR ≫ a Hubble time), and is characterized by a power-law distribution function of Eddington ratios. In this regime, the time-averaged mass accretion rate on to black holes is proportional to the mass of stars in the galaxy bulge, with a constant of proportionality that depends on the mean stellar age of the stars. This result is once again independent of black hole mass. We show that both the slope of the power law and the decrease in the accretion rate on to black holes in old galaxies are consistent with population synthesis model predictions of the decline in stellar mass loss rates as a function of mean stellar age. Our results lead to a very simple picture of black hole growth in the local Universe. If the supply of cold gas in a galaxy bulge is plentiful, the black hole regulates its own growth at a rate that does not further depend on the properties of the interstellar medium. Once the gas runs out, black hole growth is regulated by the rate at which evolved stars lose their mass. 相似文献
4.
极端质量比旋进系统是空间引力波探测器最重要的波源之一。对引力波的探测需要高精度波形模版。当前主流的极端质量比旋进系统引力波计算模型中,人们一般将小质量天体当作试验粒子进行计算,而忽略了其结构及自身引力对背景引力场的影响。利用Mathisson-Papapetrou-Dixon方程研究延展体在弯曲时空中的运动,以及小天体自旋和质量多极矩对引力波信号识别产生的影响。结果表明,质量比在10?6-10?4范围的旋进系统,其自旋达到很大时,自旋对延展体的轨道运动有不可忽略的影响;在质量比10?4-10?2区间内,需要考虑中心黑洞潮汐作用导致的白矮星形变;在质量比大于10?4,且白矮星自旋很大时,其自旋产生的形变会对小天体轨道运动产生不可忽略的影响。大质量黑洞潮汐作用导致的恒星级黑洞或中子星产生的形变可以忽略,中子星和黑洞的自旋会对轨道运动产生不可忽略的影响,而自旋产生的四极矩对轨道运动不产生影响。 相似文献
5.
The characteristics of gravitational bursts from active galactic nuclei, and globular clusters are obtained for three astrophysical situations:(i) scattering of stars by massive black holes residued at the centers of galaxies and globular clusters; (ii) the close encounters of stars in the nuclear regions of these objects; (iii) scattering of stars by black holes of stellar mass containing in the stellar population of galactic nuclei and clusters. The most effective source of gravitational bursts appears to be a scattering of stars by the massive central black holes which produces the bursts with dimensionless amplitudeh10–19–10–21 and frequencies from 10–1 to 10–5 Hz. The characteristics obtained correspond to the possiblities of a future gravitational-wave experiment with use of laser Doppler tracking of interplanetary spacecrafts. 相似文献
6.
A gravitationless black hole model is proposed in accord with a five-dimensional fully covariant Kaluza-Klein (K-K) theory
with a scalar field, which unifies the four-dimensional Einsteinian general theory of relativity and Maxwellian electromagnetic
theory. It is shown that a dense compact core of a star, when it collapses to a critical density, suddenly turns off or shields
its gravitational field. The core, if its mass exceeds an upper limit, directly collapses into a black hole. Otherwise, the
extremely large pressure, as the gravity is turned off, immediately stops the collapse and drives the mantle material of supernova
moving outward, which leads to an impulsive explosion and forms a neutron star as a remnant. A neutron star can further evolve
into a black hole when it accretes enough matter from a companion star such that the total mass exceeds a lower limit. The
black hole in the K-K theory is gravitationless at the surface because the scalar field is infinitely strong, which varies
the equivalent gravitational constant to zero. In general, a star, at the end of its evolution, is relatively harder to collapse
into a gravitationless K-K black hole than a strong gravitational Schwarzschild black hole. This is consistent with the observation
of some very massive stars to form neutron stars rather than expected black holes. In addition, the gravitationless K-K black
hole should be easier to generate jets than a Schwarzschild black hole. 相似文献
7.
Guinevere Kauffmann Martin Haehnelt 《Monthly notices of the Royal Astronomical Society》2000,311(3):576-588
We incorporate a simple scheme for the growth of supermassive black holes into semi-analytic models that follow the formation and evolution of galaxies in a cold dark matter-dominated Universe. We assume that supermassive black holes are formed and fuelled during major mergers. If two galaxies of comparable mass merge, their central black holes coalesce and a few per cent of the gas in the merger remnant is accreted by the new black hole over a time-scale of a few times 107 yr. With these simple assumptions, our model not only fits many aspects of the observed evolution of galaxies, but also reproduces quantitatively the observed relation between bulge luminosity and black hole mass in nearby galaxies, the strong evolution of the quasar population with redshift, and the relation between the luminosities of nearby quasars and those of their host galaxies. The strong decline in the number density of quasars from z ∼2 to z =0 is a result of the combination of three effects: (i) a decrease in the merging rate; (ii) a decrease in the amount of cold gas available to fuel black holes, and (iii) an increase in the time-scale for gas accretion. The predicted decline in the total content of cold gas in galaxies is consistent with that inferred from observations of damped Ly α systems. Our results strongly suggest that the evolution of supermassive black holes, quasars and starburst galaxies is inextricably linked to the hierarchical build-up of galaxies. 相似文献
8.
Sun Yu-Tao Liu Jie-Ying Liu Jin-zhong Ai Yan-Li Zhou Ming Qiao Er-lin 《Chinese Astronomy and Astrophysics》2011,35(2):103
The research on quasar OJ 287 has lasted over 100 years. OJ 287 exhibits the phenomenon of periodic two-peak outbursts with the eruptive period of 12 years. Observations are rather well interpreted with the black hole binary model. In this model, the secondary black hole moves around the primary black hole and crashes against the accretion disk of the primary black hole, causing outbursts. This model reasonably explains the light curves of OJ 287 and correctly predicts the time of future outbursts. These indirectly justify the precessional effect of general relativity and the existence of gravitational waves. The massive black hole in the center of galaxy is an important kind of gravitational wave source. However, the number of the galaxies with precisely determined kinematical equations of inner components is quite small. The precise kinematic orbits of black holes are provided by the black hole binary model, so the radiation of gravitational waves can be studied on the basis of these kinematic orbits. Based on the existing work, the evolutionary relations of the radiation power and waveform of gravitational waves with time are first derived by using the post-Newtonian approximation method. According to the current progress of the detection equipment of gravitational waves, i.e., IPTA (International Pulsar Timing Array), the direct detection of gravitational waves from OJ 287 may be possible within the future decade. 相似文献
9.
Andrea Cattaneo Martin G. Haehnelt Martin J. Rees 《Monthly notices of the Royal Astronomical Society》1999,308(1):77-81
The growth of supermassive black holes by merging and accretion in hierarchical models of galaxy formation is studied by means of Monte Carlo simulations. A tight linear relation between masses of black holes and masses of bulges arises if the mass accreted by supermassive black holes scales linearly with the mass-forming stars and if the redshift evolution of mass accretion tracks closely that of star formation. Differences in redshift evolution between black hole accretion and star formation introduce a considerable scatter in this relation. A non-linear relation between black hole accretion and star formation results in a non-linear relation between masses of remnant black holes and masses of bulges. The relation of black hole mass to bulge luminosity observed in nearby galaxies and its scatter are reproduced reasonably well by models in which black hole accretion and star formation are linearly related but do not track each other in redshift. This suggests that a common mechanism determines the efficiency for black hole accretion and the efficiency for star formation, especially for bright bulges. 相似文献
10.
Massive stars are of interest as progenitors of supernovae, i.e. neutron stars and black holes, which can be sources of gravitational waves. Recent population synthesis models can predict neutron star and gravitational wave observations but deal with a fixed supernova rate or an assumed initial mass function for the population of massive stars. Here we investigate those massive stars, which are supernova progenitors, i.e. with O‐ and early B‐type stars, and also all supergiants within 3 kpc. We restrict our sample to those massive stars detected both in 2MASS and observed by Hipparcos, i.e. only those stars with parallax and precise photometry. To determine the luminosities we calculated the extinctions from published multi‐colour photometry, spectral types, luminosity class, all corrected for multiplicity and recently revised Hipparcos distances. We use luminosities and temperatures to estimate the masses and ages of these stars using different models from different authors. Having estimated the luminosities of all our stars within 3 kpc, in particular for all O‐ and early B‐type stars, we have determined the median and mean luminosities for all spectral types for luminosity classes I, III, and V. Our luminosity values for supergiants deviate from earlier results: Previous work generally overestimates distances and luminosities compared to our data, this is likely due to Hipparcos parallaxes (generally more accurate and larger than previous ground‐based data) and the fact that many massive stars have recently been resolved into multiples of lower masses and luminosities. From luminosities and effective temperatures we derived masses and ages using mass tracks and isochrones from different authors. From masses and ages we estimated lifetimes and derived a lower limit for the supernova rate of ≈20 events/Myr averaged over the next 10 Myr within 600 pc from the sun. These data are then used to search for areas in the sky with higher likelihood for a supernova or gravitational wave event (like OB associations) (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
王建民 《紫金山天文台台刊》1999,18(3):271-273
频繁的超新星爆发可用以解释活动星系核与类星体的超高金属丰度。星团中的恒星与吸积盘相互作用导致致密天体中子星和黑洞的形成率很高,这些致密天体与红巨星很容易形成双星系统,而后形成（ＮＳ／ＢＨ,ＮＳ／ＢＨ） 双星由于引力辐射最终导致并合而形成伽玛射线爆发。我们估计了伽玛射线爆的爆发频率,发现与观测相符。 相似文献
12.
In the first part of the paper the known results on the gravitational interaction of a massive black hole with the surrounding stars in a galactic nucleus are discussed. The tidal disruption of stars in close encounters with a black hole is reviewed. Expressions for the flux of stars on a black hole are given, taking into account energy and angular momentum diffusion of stellar orbits. The scenario of star disruption and accretion of the released stellar matter is depicted. The growth of a black hole in a typical galactic nucleus on account of gas accretion from disrupted stars is discussed. A comparison with the upper limit to the luminosity of the nucleus of our Galaxy puts rather severe constraints on the mass of a hypothetical black hole at the galactic centre. Possible mechanisms preventing the formation and growth of black holes in normal galactic nuclei are discussed.The second part of the paper (Section 8) deals with the hypothesis that massive black holes are the primary energy sources in active galaxies and quasars. The luminosity requirements of bright quasars and weak Seyferts can probably be accounted for in such a model, but there are difficulties in explaining the intermediate range. Mass ejection from Seyferts and quasars is not a severe problem. The same applies to the spectrum. A much more serious objection is the observed periodic and quasi-periodic variability. Another unsatisfactory feature of this hypothesis is that one needs two different evolutionary tracks for quasars and active galaxies, and for normal galaxies. 相似文献
13.
Active galactic nuclei and pulsars as cosmic ray sources 总被引：2，自引：0，他引：2
N.S. Kardashev 《Monthly notices of the Royal Astronomical Society》2001,326(3):1122-1126
Relativistic e± particles and cosmic rays are accelerated in the magnetospheres of supermassive black holes and neutron stars. The possibility of synchrotron radiation with extremely high intensity inside the deepest regions of magnetospheres is investigated. Very high brightness temperatures are expected for such radiation by relativistic protons, which can be made even higher in the presence of non-stationary conditions, Doppler boosting and coherent processes. The main parameters for models of such high-brightness-temperature radiation are determined. Two types of active galactic nuclei (AGNs) are expected. One type is associated with the acceleration and ejection of relativistic e± particles only (probably non-IDV sources and FR-I radio galaxies). The second type of AGN is also associated with e± acceleration, but is dominated by the contribution of relativistic protons (probably IDV sources and FR-II radio galaxies). Analogous objects for pulsars are plerion and shell supernova remnants with neutron stars or pulsars without synchrotron nebulae, respectively. 相似文献
14.
Karnig O. Mikaelian 《Astrophysics and Space Science》1978,57(1):245-247
We suggest that only slowly spinning stars undergoing gravitational collapse can eject their envelope in a supernova explosion and leave behind a remnant in the form of a neutron star or a pulsar. Faster spinning stars fail to explode and perhaps become black holes.Work supported in part by the National Science Foundation under Grant Nos PHY75-21591 and PHY76-11445. 相似文献
15.
S. Harfst A. Gualandris D. Merritt S. Mikkola 《Monthly notices of the Royal Astronomical Society》2008,389(1):2-12
We describe a novel N -body code designed for simulations of the central regions of galaxies containing massive black holes. The code incorporates Mikkola's 'algorithmic' chain regularization scheme including post-Newtonian terms up to PN2.5 order. Stars moving beyond the chain are advanced using a fourth-order integrator with forces computed on a GRAPE board. Performance tests confirm that the hybrid code achieves better energy conservation, in less elapsed time, than the standard scheme and that it reproduces the orbits of stars tightly bound to the black hole with high precision. The hybrid code is applied to two sample problems: the effect of finite- N gravitational fluctuations on the orbits of the S-stars, and inspiral of an intermediate-mass black hole into the Galactic Centre. 相似文献
16.
James Etherington Witold Maciejewski 《Monthly notices of the Royal Astronomical Society》2006,367(3):1003-1010
If supermassive black holes in centres of galaxies form by merging of black hole remnants of massive Population III stars, then there should be a few black holes of mass one or two orders of magnitude smaller than that of the central ones, orbiting around the centre of a typical galaxy. These black holes constitute a weak perturbation in the gravitational potential, which can generate wave phenomena in gas within a disc close to the centre of the galaxy. Here, we show that a single orbiting black hole generates a three-arm spiral pattern in the central gaseous disc. The density excess in the spiral arms in the disc reaches values of 3–12 per cent when the orbiting black hole is about 10 times less massive than the central black hole. Therefore, the observed density pattern in gas can be used as a signature in detecting the most massive orbiting black holes. 相似文献
17.
J. Camp S. Barthelmy L. Blackburn K. G. Carpenter N. Gehrels J. Kanner F. E. Marshall J. L. Racusin T. Sakamoto 《Experimental Astronomy》2013,36(3):505-522
The International Space Station offers a unique platform for rapid and inexpensive deployment of space telescopes. A scientific opportunity of great potential later this decade is the use of telescopes for the electromagnetic follow-up of ground-based gravitational wave detections of neutron star and black hole mergers. We describe this possibility for OpTIIX, an ISS technology demonstration of a 1.5 m diffraction limited optical telescope assembled in space, and ISS-Lobster, a wide-field imaging X-ray telescope now under study as a potential NASA mission. Both telescopes will be mounted on pointing platforms, allowing rapid positioning to the source of a gravitational wave event. Electromagnetic follow-up rates of several per year appear likely, offering a wealth of complementary science on the mergers of black holes and neutron stars. 相似文献
18.
We study universality in gravitational waves emitted from non-rotating neutron stars characterized by different equations of state (EOSs). We find that the quasi-normal mode frequencies of such waves, including the w -modes and the f -mode, display similar universal scaling behaviours that hold for most EOSs. Such behaviours are shown to stem from the mathematical structure of the axial and the polar gravitational wave equations, and the fact that the mass distribution function can be approximated by a cubic–quintic polynomial in the radius. As a benchmark for other realistic neutron stars, a simple model of neutron stars is adopted here to reproduce the pulsation frequencies and the generic scaling behaviours mentioned above with good accuracy. 相似文献
19.
Martin G. Haehnelt Priyamvada Natarajan & Martin J. Rees 《Monthly notices of the Royal Astronomical Society》1998,300(3):817-827
We demonstrate that the luminosity function of the recently detected population of actively star-forming galaxies at redshift z = 3 and the B -band luminosity function of quasi-stellar objects (QSOs) at the same redshift can both be matched with the mass function of dark matter haloes predicted by standard variants of hierarchical cosmogonies for lifetimes of optically bright QSOs anywhere in the range 106 to 108 yr. There is a strong correlation between the lifetime and the required degree of non-linearity in the relation between black hole and halo mass. We suggest that the mass of supermassive black holes may be limited by the back-reaction of the emitted energy on the accretion flow in a self-gravitating disc. This would imply a relation of black hole to halo mass of the form M bh ∝ v 5 halo ∝ M 5/3 halo and a typical duration of the optically bright QSO phase of a few times 107 yr. The high integrated mass density of black holes inferred from recent black hole mass estimates in nearby galaxies may indicate that the overall efficiency of supermassive black holes for producing blue light is smaller than previously assumed. We discuss three possible accretion modes with low optical emission efficiency: (i) accretion at far above the Eddington rate, (ii) accretion obscured by dust, and (iii) accretion below the critical rate leading to an advection-dominated accretion flow lasting for a Hubble time. We further argue that accretion with low optical efficiency might be closely related to the origin of the hard X-ray background and that the ionizing background might be progressively dominated by stars rather than QSOs at higher redshift. 相似文献
20.
Wytler Cordeiro dos Santos 《Astrophysics and Space Science》2011,331(1):295-307
The Laser Interferometer Space Antenna (LISA) mission will use advanced technologies to achieve its science goals: the direct
detection of gravitational waves, the observation of signals from compact (small and dense) stars as they spiral into black
holes, the study of the role of massive black holes in galaxy evolution, the search for gravitational wave emission from the
early Universe. The gravitational red-shift, the advance of the perihelion of Mercury, deflection of light and the time delay
of radar signals are the classical tests in the first order of General Relativity (GR). However, LISA can possibly test Einstein’s
theories in the second order and perhaps, it will show some particular feature of non-linearity of gravitational interaction.
In the present work we are seeking a method to construct theoretical templates that limit in the first order the tensorial
structure of some metric fields, thus the non-linear terms are given by exponential functions of gravitational strength. The
Newtonian limit obtained here, in the first order, is equivalent to GR. 相似文献