Related papers: Analysis of interacting and isolated quasars
If high-redshift QSOs are ejected from the nuclei of low-redshift galaxies, as some have claimed, a large portion of their redshift must be intrinsic (non-Doppler). If these intrinsic components have preferred values, redshifts will tend to…
We have obtained H-band spectra of 32 luminous quasars at 2.0<z<2.5 with the Multiple Mirror Telescope. The sample contains 15 radio-loud quasars (RLQs) and 17 radio-quiet quasars (RQQs). We have measured emission line properties from the…
We present a catalog of 208 $0.3 < z < 2.1$ Emission Line Galaxies (ELG) selected from 1D slitless spectroscopy obtained using Hubble's WFC3 G102 grism, as part of the Faint Infrared Grism Survey (FIGS). We identify ELG candidates by…
Quasar emission lines are often shifted from the systemic velocity due to various dynamical and radiative processes in the line-emitting region. The level of these velocity shifts depends both on the line species and on quasar properties.…
Insight into quasar ages may be obtained from the proximity effect, but so far only in a limited number of bright quasars. Based on ~2600 SDSS quasar spectra at 2.5 <= z <= 3.5, a search for spectral voids between Ly-alpha forest lines…
We analyse the proximity zone of the intergalactic matter around high-redshift quasars in a cosmological environment. In a box of 64 h-1 Mpc base length we employ dark matter only simulations. For estimating the hydrogen temperature and…
In this paper we report new evidence that measurements of the broad-line widths in quasars are dependent on the source orientation, consistent with the idea that the broad-line region is flattened or disc-like. This reinforces the view…
We discuss observational evidence that quasars play a key role in the formation of galaxies starting from the detailed study of the quasar HE0450-2958 and extending the discussion to a series of converging evidence that radio jets may…
A small subset of optically selected radio-quiet quasars showing weak or no emission lines may turn out to be the elusive radio-quiet BL Lac objects, or simply be radio-quiet QSOs with a still-forming/shielded broad line region (BLR). High…
In a single optical spectrum, the quasar narrow-line region (NLR) reveals low density, photoionized gas in the host galaxy interstellar medium, while the immediate vicinity of the central engine generates the accretion disk continuum and…
Several recent studies show that bright, intermediate and high redshift optically and radio selected QSOs are positively correlated with nearby galaxies on a range of angular scales up to a degree. Obscuration by unevenly distributed…
The non-linear relation between the UV and X-ray luminosity in quasars has been studied for decades. However, as we lack a comprehensive model able to explain it, its investigation still relies on observational efforts. This work focuses on…
The planet-star interaction is manifested in many ways. It was found out that a close-in exoplanet causes small but measurable variability in the cores of a few lines in the spectra of several stars which corresponds to the orbital period…
The co-evolution between black holes and galaxies suggests that feedback of active galactic nuclei influence host galaxies through ejecting radiative and kinetic energies to surroundings. Larger scale outflow in local universe are…
We present optical spectroscopy of the close companions of 22 low redshift (z<0.5) quasars (QSO) selected from a larger sample of QSO in the SDSS Stripe82 region for which both the host galaxy and the large scale environments have been…
Galaxies hosting z~2 quasars are the high-$z$ progenitors of today's massive `red-and-dead' galaxies. With close pairs of quasars at different redshifts, a background quasar can be used to study a foreground quasar's halo gas in absorption,…
We present a systematic study of the internal mass structure of early-type galaxies (ETGs) based on 106 galaxy-scale strong gravitational lenses with background quasars, all having spectroscopic redshifts. From this parent sample, we select…
We report a detection of galaxy-QSO cross-correlation w_GQ in the Sloan Digital Sky Survey (SDSS) Early Data Release (EDR) over 0.2-30 arc-minute scales. We cross-correlate galaxy samples of different mean depths r'=19-22 (z_G =0.15-0.35)…
This paper presents new optical and near-UV spectra of 11 extremely powerful jetted quasars, with radio to optical flux density ratio $>$ 10$^3$, that concomitantly cover the low-ionization emission of \mgii\ and \hb\ as well as the \feii\…
We test the hypothesis whether high redshift QSOs would preferentially appear in small groups or pairs, and if they are associated with massive, young clusters. We carried out a photometric search for \Ly emitters on scales $\lesssim 10…