Related papers: The radio-loudness dichotomy: environment or black…
Using a sample of more than 6000 quasars from the Sloan digital sky survey (SDSS) we compare the black-hole mass distributions of radio-loud and radio-quiet quasars. Based on the virial black-hole mass estimator the radio-loud quasars…
The central black-hole masses of a sample of radio-loud quasars are estimated by using the data of $H_{\beta}$ line-width and the optical continuum luminosity. The vast majority of the quasars in this sample have black-hole masses larger…
Evidence has accumulated suggesting the clustering of radio loud quasars is greater than for radio quiet quasars. We interpret these results in a context in which the fraction of radio loud quasar formation is less than or equal to that for…
We use a homogeneous sample of about 300, 0.3 <~ z <~ 3, radio-loud quasars drawn from the FIRST and 2dF QSO surveys to investigate a possible dependence of radio activity on black-hole mass. By analyzing composite spectra for the…
A new analysis of the connection between black-hole mass and radio luminosity in radio-selected flat-spectrum quasars (FSQ) is presented. In contrast to recent claims in the literature, we find no evidence that the black-hole masses of…
We examine the fundamental plane of black hole activity for correlations with redshift and radio loudness in both radio-loud and radio-quiet quasar populations. Sources are compiled from archival data of both radio-loud and radio-quiet…
We have observed the galaxy environments around two complete samples of radio-loud (steep-spectrum) and radio-quiet quasars (RLQ and RQQ) at 0.5 < z < 0.8 that are matched in B-luminosity, and find that the environments of both quasar…
We have quantified the galaxy environments around a sample of 0.5 < z < 0.8 radio-quiet quasars using the amplitude of the spatial galaxy--quasar correlation function, B_gq. The quasars exist in a wide variety of environments, some sources…
I review our knowledge of the properties of the host galaxies of radio-loud and radio-quiet quasars, both in comparison to each other and in the context of the general galaxy population. It is now clear that the hosts of radio-loud and…
One of the major unsolved questions on the understanding of the AGN population is the origin of the dichotomy between radio-quiet and radio-loud quasars. The most promising explanation is provided by the spin paradigm, which suggests…
We have assembled a sample of 37 RLQs that have been imaged with the HST in order to investigate their black hole masses, accretion rates, and the structure of their accretion disks. The black hole masses were estimated from the…
Black holes with masses M_BH~10^{8.5} M_Sun dominate the accretion history of the Universe. These black hole masses are typical of those found in radio-selected galaxies today, suggesting that the giant elliptical hosts of low redshift…
Several independent lines of evidence now point to a correlation between black hole mass, M_bh, and radio-luminosity. In this paper we discuss the correlation for quasars from the FIRST Bright Quasar Survey (FBQS), using black hole mass…
Over the past few years, we have been collecting data with the Nordic Optical Telescope (NOT) on the galaxy environments around active galactic nuclei (AGN). Here we present some results from a sample of 21 radio-loud and 20 radio-quiet…
The distribution of radio to optical fluxes in AGN is bimodal. The physical origin for this bimodality is not understood. In this Letter I describe observational evidence, based on the Boroson & Green PG quasar sample, that the radio…
We investigate the clustering properties of 45441 radio-quiet quasars (RQQs) and 3493 radio-loud quasars (RLQs) drawn from a joint use of the Sloan Digital Sky Survey (SDSS) and Faint Images of the Radio Sky at 20 cm (FIRST) surveys in the…
The origin of the dichotomy of radio loudness among quasars can be explained using recent findings that the mass of the central supermassive black hole (SMBH) in extended radio-loud quasars is systematically a few times that of their…
It has been inferred from large unbiased samples that $10\%$-$15\%$ of all quasars are radio-loud (RL). Using the quasar catalog from the Sloan Digital Sky Survey, we show that the radio-loud fraction (RLF) for high broad line (HBL)…
We investigate the $\mbh- \sigma_*$ relation for radio-loud quasars with redshift $z<0.83$ in Data Release 3 of the Sloan Digital Sky Survey (SDSS). The sample consists of 3772 quasars with better model of H$\beta$ and \oiii lines and…
The black hole (BH) mass in the centre of AGN has been estimated for a sample of radio-selected flat-spectrum quasars to investigate the relationship between BH mass and radio properties of quasars. We have used the virial assumption with…