Related papers: A Structure for Quasars
We have compiled the largest sample of multiwavelength spectral energy distributions (SEDs) of Broad Absorption Line (BAL) quasars to date, from the radio to the X-ray. We present new Spitzer MIPS (24, 70, and 160 micron) observations of 38…
The broad absorption line (BAL) features seen in a small fraction of quasar optical/UV spectra are attributed to bulk outflows away from the quasar core. Observational evidence suggests that dust plays a key role in these systems, although…
Low-ionization broad absorption line (BAL) QSOs present properties that cannot generally be explained by simple orientation effects. We have conducted a deep spectroscopic and imaging study of the host galaxies of the only four BAL QSOs…
There is a large diversity in the C IV broad absorption line (BAL) profile among BAL quasars (BALQs). We quantify this diversity by exploring the distribution of the C IV BAL properties, FWHM, maximum depth of absorption and its velocity…
One primary difficulty in understanding the nature of the putative accretion disk in the central engine of AGNs is that some of its key intrinsic spectral signatures are buried under the emissions from the surrounding regions, i.e. the…
Broad-line regions (BLR) are one of the main components that constitute the phenomenological picture of active galaxies near the vicinity of the accreting supermassive black holes. Both theoretical and observational studies have shown that…
Quasar spectra have a variety of absorption lines whose origins range from energetic winds expelled from the central engines to unrelated, intergalactic clouds. We present multi-epoch, medium resolution spectra of eight quasars at z~2 that…
Associated absorption lines (AALs) in quasar spectra are valuable probes of the gas kinematics and physical conditions in quasar environments. The host galaxies are by definition in an active evolution stage that might involve large-scale…
We report on the results of XMM-Newton observations of two Broad Absorption Line Quasars (BAL QSOs), Q1246-057 and SBS 1542+541. Unprecedented sensitivity of XMM allows spectral analysis of these X-ray weak sources. The X-ray spectral data…
The blue-shifted broad absorption lines (BAL) or troughs are observed in Active Galactic Nuclei (AGNs) when our line of sight is intercepted by a high speed outflow (wind), likely originating in the accretion disc. The outflow or wind can…
Broad absorption line quasars (BALQs) present a large diversity in their broad absorption line (BAL) profiles. To investigate what physical parameters underlie this diversity, we construct a sample of BALQs which covers lambda_rest ~…
We report the first discovery of the emergence of a high-velocity broad-line outflow in a luminous quasar, J105400.40+034801.2 at redshift z ~ 2.1. The outflow is evident in ultraviolet CIV and SiIV absorption lines with velocity shifts v ~…
Recent models for the emission clouds within the Broad Line Region of quasars suggest that they are due to transient overdensities within an overall turbulent medium. If this were the case, the broad line emission would spatially appear…
Gravitational microlensing is a powerful tool allowing one to probe the structure of quasars on sub-parsec scale. We report recent results, focusing on the broad absorption and emission line regions. In particular microlensing reveals the…
The large magnification factors of gravitationally lensed (GL) systems allow us to investigate the properties of quasars with X-ray luminosities that are substantially lower than those of unlensed ones and also provide an independent means…
The formation of quasar broad-line region (BLR) clouds via thermal instability in the presence of Alfven heating has been discussed by Goncalves et al. (1993a, 1996). In particular, these studies showed the relevance of Alfven heating in…
Broad absorption lines (BALs) in quasar spectra identify high velocity outflows that likely exist in all quasars and could play a major role in feedback to galaxy evolution. The variability of BALs can help us understand the structure,…
Some fraction of narrow absorption lines are physically associated to the quasar/host-galaxy materials (i.e., intrinsic NALs) like those of BALs and mini-BALs. The relation between these three types of absorption lines has not been…
A variety of investigations have demonstrated commonalities between the Baldwin (1977) Effect, the blueshifting of CIV emission lines (e.g., Gaskell 1982; Richards et al. 2002), and the L_UV-L_X relationship (e.g., Avni & Tananbaum 1982;…
New reverberation mapping measurements of the size of the optical iron emission-line region in quasars are provided, and a tentative size-luminosity relation for this component is reported. Combined with lag measurements in low-luminosity…