共查询到20条相似文献，搜索用时 31 毫秒
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We explore the relation between the linear length of radio core and the central black hole mass for a sample of radio-loud active galactic nuclei (AGNs). An empirical relation between the size of the broad line region (BLR) and optical luminosity is used to estimate the size of the BLR. The black hole mass is derived from H β linewidth and the radius of the BLR on the assumption that the clouds in BLRs are orbiting with Keplerian velocities. A significant intrinsic correlation is found between the linear length of the core and the black hole mass, which implies that the jet formation is closely related with the central black hole. We also find a strong correlation between the black hole mass and the core luminosity. 相似文献
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M. Labita A. Treves R. Falomo M. Uslenghi 《Monthly notices of the Royal Astronomical Society》2006,373(2):551-560
We report on the analysis of the photometric and spectroscopic properties of a sample of 29 low-redshift ( z < 0.6) QSOs for which both Hubble Space Telescope ( HST ) WFPC2 images and ultraviolet HST FOS spectra are available. For each object we measure the R -band absolute magnitude of the host galaxy, the C iv (1550 Å) linewidth and the 1350 Å continuum luminosity. From these quantities we can estimate the black hole (BH) mass through the M BH – L bulge relation for inactive galaxies, and from the virial method based on the kinematics of the regions emitting the broad-lines. The comparison of the masses derived from the two methods yields information on the geometry of the gas emitting regions bound to the massive BH. The cumulative distribution of the linewidths is consistent with that produced by matter laying in planes with inclinations uniformly distributed between ∼10° and ∼50°, which corresponds to a geometrical factor f ∼ 1.3 . Our results are compared with those of the literature and discussed within the unified model of active galactic nuclei. 相似文献
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R. J. McLure M. J. Jarvis T. A. Targett J. S. Dunlop P. N. Best 《Monthly notices of the Royal Astronomical Society》2006,368(3):1395-1403
We present the results of a study which uses the 3C RR sample of radio-loud active galactic nuclei to investigate the evolution of the black hole:spheroid mass ratio in the most massive early-type galaxies from 0 < z < 2 . Radio-loud unification is exploited to obtain virial (linewidth) black hole mass estimates from the 3C RR quasars, and stellar mass estimates from the 3C RR radio galaxies, thereby providing black hole and stellar mass estimates for a single population of early-type galaxies. At low redshift ( z ≲ 1) , the 3C RR sample is consistent with a black hole:spheroid mass ratio of M bh / M sph ≃ 0.002 , in good agreement with that observed locally for quiescent galaxies of similar stellar mass ( M sph ≃ 5 × 1011 M⊙ ) . However, over the redshift interval 0 < z < 2 the 3C RR black hole:spheroid mass ratio is found to evolve as M bh / M sph ∝ (1 + z )2.07±0.76 , reaching M bh / M sph ≃ 0.008 by redshift z ≃ 2 . This evolution is found to be inconsistent with the local black hole:spheroid mass ratio remaining constant at a moderately significant level (98 per cent). If confirmed, the detection of evolution in the 3C RR black hole:spheroid mass ratio further strengthens the evidence that, at least for massive early-type galaxies, the growth of the central supermassive black hole may be completed before that of the host spheroid. 相似文献
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Stefano Cristiani 《Astrophysics and Space Science》2004,294(1-2):79-87
I had the privilege, many years ago, to be supervised by Alfonso Cavaliere in my Master thesis work. I remember the great
patience and enthusiasm with which, in a warm summer day, he presented to me a score of exciting astrophysical problems. We
finally determined to study the relationship of QSOs and BL Lacs—then considered rather exotic object—with normal galaxies.
In the years I have continued on this line of research, reacting far too slowly to the wealth of new ideas that Alfonso has
been continuously injecting in our conversations. As examples I will report two recent results on the chemical abundances
of QSO host galaxies and on the space density of high-z QSOs, which are closely related to our shared interest on AGN. 相似文献
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Paul Hirst Neal Jackson Steve Rawlings 《Monthly notices of the Royal Astronomical Society》2003,346(3):1009-1020
We have obtained near-infrared spectroscopy of a small sample of powerful compact steep-spectrum (CSS) radio sources mainly, but not exclusively, from the 3CR sample. We find no differences between the distributions in the equivalent width and luminosity of the [O iii ]λ5007 line for our sample and other larger, presumably older, high-redshift 3C objects, suggesting that the underlying quasar luminosity remains roughly constant as quasars age. We also find a possible broad line in 3C 241, adding to recent evidence for broad lines in some radio galaxies. 相似文献
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