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11.
We report three new or updated techniques for probing the parameters of active galaxies based on the masses of their central
black holes MBH). First, we derived a near-IR analog of the bulge luminosity versus MBH relationship. The low scatter makes it a promising new tool to study the black hole demographics. Next, we present relations
between MBH and the10 μm and 2-10 keV nuclear luminosity. They may help to study the MBH evolution over wide redshift ranges. Finally, we measured MBH in quasars from z ∼ 3.4 to z ∼ 0.3 to search directly for MBH growth. Surprisingly, we found no evidence for growth implying that the majority of quasar host galaxies have undergone their
last major merger at z ≥ 3.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
Piero F. Spinnato Michael Fellhauer Simon F. Portegies Zwart 《Monthly notices of the Royal Astronomical Society》2003,344(1):22-32
We study the efficiency at which a black hole or dense star cluster spirals in to the Galactic Centre. This process takes place on a dynamical friction time-scale, which depends on the value of the Coulomb logarithm (ln Λ). We determine the accurate value of this parameter using the direct N -body method, a tree algorithm and a particle-mesh technique with up to two million plus one particles. The three different techniques are in excellent agreement. Our measurement for the Coulomb logarithm appears to be independent of the number of particles. We conclude that ln Λ= 6.6 ± 0.6 for a massive point particle in the inner few parsec of the Galactic bulge. For an extended object, such as a dense star cluster, ln Λ is smaller, with a value of the logarithm argument Λ inversely proportional to the object size. 相似文献
13.
超基性岩中含铜、钴块状硫化物矿床——德尔尼铜矿成因新认识 总被引:1,自引:0,他引:1
长期以来对德尔尼铜矿的成因存在着不同认识。从矿石组成和结构、构造来看,应属典型的块状硫化物矿石,矿床亦应属于含铜黄铁矿型矿床。但从其地质产状来看又与一般的黄铁矿型矿床大不相同,与一般的岩浆熔离铜镍硫化物矿床也有较多差异。这就是本矿床类型独特之处。近年来通过工作又取得一些新资料,特别是超基性岩和矿石的同位素年龄数据。本文在综合新老资料基础上,提出新看法,认为该矿床形成于上地幔,再就位于地壳浅部。其成因类型暂定为:“深部熔离—构造侵位矿床”。鉴于本矿床与一般块状硫化物矿床相比有其独特性,建议命名为“德尔尼型”。 相似文献
14.
The lensing properties of the Plummer model with a central point mass and external shear are derived, including the image multiplicities, critical curves and caustics. This provides a simple model for a flattened galaxy with a central supermassive black hole. For the Plummer model with black hole, the maximum number of images is four, provided the black hole mass is less than an upper bound which is calculated analytically. This introduces a method to constrain black hole masses by counting images, thus applicable at cosmological distance. With shear, the maximum number of images is six and we illustrate the occurrence of an astroid caustic and two metamorphoses. 相似文献
15.
K. A. van der Hucht 《Astronomy and Astrophysics Review》1992,4(2):123-159
Summary Recent literature on Population I Wolf-Rayet star research extending from the Milky Way to blue compact dwarf galaxies is reviewed, broken down into inventory, basic parameters and galactic distribution, atmospheres, binaries, intrinsic variability, mass loss, enrichment and evolution. Also the incidence of Wolf-Rayet stars with variable non-thermal radio emission, excess X-ray fluxes, and episodic/periodic IR excesses is reviewed. These phenomena appear to be associated with wind-wind interaction in wide long-period WR+OB binaries and with wind-compact object interaction in WR+c binaries, with orbit sizes of the order of magnitude of the WR radio photosphere sizes or larger. 相似文献
16.
Benedetta Ciardi † rea Ferrara 《Monthly notices of the Royal Astronomical Society》2001,324(3):648-652
We calculate the expected mid-infrared (MIR) molecular hydrogen line emission from the first objects in the Universe. As a result of their low masses, the stellar feedback from massive stars is able to blow away their gas content and collect it into a cooling shell where H2 rapidly forms and IR roto-vibrational (as for example the rest-frame 2.12 μm) lines carry away a large fraction (up to 10 per cent) of the explosion energy. The fluxes from these sources are in the range 10−21 –10−17 erg s−1 cm−2 . The highest number counts are expected in the 20-μm band, where about 105 sources deg−2 are predicted at the limiting flux of 3×10−18 erg s−1 cm−2 . Among the planned observational facilities, we find that the best detection perspectives are offered by the Next Generation Space Telescope ( NGST ), which should be able to reveal about 200 first objects in one hour observation time at its limiting flux in the above band. Therefore, mid-IR instruments appear to represent perfect tools to trace star formation and stellar feedback in the high ( z ≳5) redshift Universe. 相似文献
17.
We have recently put forward a ‘unified’ semi-empirical model for the coupling between accretion and jet production in galactic
black hole X-ray binaries. In this paper, we summarise this model and briefly discuss relevant considerations that have arisen
since its publication. 相似文献
18.
19.