Related papers: Polarization of changing-look quasars
We present spectropolarimetry of 19 confirmed and 4 possible bright, southern broad absorption line (BAL) quasars from the European Southern Observatory (ESO) Very Large Telescope (VLT). A wide range of redshifts is covered in the sample…
It is becoming clear that the atmospheres of the young, self-luminous extrasolar giant planets imaged to date are dusty. Planets with dusty atmospheres may exhibit detectable amounts of linear polarization in the near-infrared, as has been…
With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasar's environment in absorption. We used a sample of 17 Lyman limit systems with column density N_HI > 10^19 cm^-2…
Polarimetry of the narrow-line radio galaxy PKS 0116+082 at the W.M. Keck telescope shows that it has high and variable optical polarization, presumably due to synchrotron radiation. It is not a BL Lac object because it has strong narrow…
Reverberation mapping of nearby active galactic nuclei has led to estimates of broad-line-region (BLR) sizes and central-object masses for some 37 objects to date. However, successful reverberation mapping has yet to be performed for…
We explore the extinction/reddening of ~35,000 uniformly selected quasars with 0<z<5.3 in order to better understand their intrinsic optical/ultraviolet spectral energy distributions. Using rest-frame optical-UV photometry taken from the…
We have carried out a survey to search for hidden blazars in a sample of $z{\sim}2$ radio-loud quasars. The idea is based on our prediction that we should be able to see large CIV line variability not associated with observed continuum…
It has been suggested that relativistic jets in quasars may contain a considerable amount of thermal matter. In this paper, we explore the possibility that the K-alpha line from the thermal matter may appear at tens of keV due to a high…
We present ALMA CO observations of the molecular gas in a sample of 41 luminous unobscured quasars at z $\sim$ 2 from the Sloan Digital Sky Survey. 32 targets comprise the main sample observed in CO(3-2) and 9 targets have archival ALMA…
Since the discovery of kiloparsec-scale X-ray emission from quasar jets, the physical processes responsible for their high-energy emission have been poorly defined. A number of mechanisms are under active debate, including synchrotron…
"Changing-look quasars" (CLQs), discovered less than a decade ago, show dramatic, rapid changes in optical/UV continuum and broad line emission. The majority of CLQs have been found dimming as "turn-off" CLQs because most selection methods…
The relative brightnesses of strongly lensed quasar images, called flux ratios, respond to perturbations from low-mass dark matter halos, enabling tests of dark matter models. The quasar narrow-line region (NLR) is ideal for flux-ratio…
We explore the connection between absorption by neutral gas and extinction by dust in mid-infrared (IR) selected luminous quasars. We use a sample of 33 quasars at redshifts 0.7 < z < 3 in the 9 deg^2 Bo\"otes multiwavelength survey field…
A fraction of quasars present broad absorption lines, produced by outflowing gas with typical velocities of 3000 - 10,000 km/s. If the outflowing gas fills a significant fraction of the volume where it resides, then it will be highly…
We present results of a study of 12 dust-reddened quasars with 0.4 < z < 2.65 and reddenings in the range 0.15 < E(B-V) < 1.7. We obtained ACIS-S X-ray spectra of these quasars, estimated the column densities towards them, and hence…
Previous observations of quasar host halos at z=2 have uncovered large quantities of cool gas that exceed what is found around inactive galaxies of both lower and higher masses. To better understand the source of this excess cool gas, we…
In classifying the ensemble of powerful extragalactic radio sources, considerable evidence has accumulated that radio galaxies and quasars are orientation-dependent manifestations of the same parent population: massive spheroidal galaxies…
We report spectropolarimetric observations obtained with the W.M. Keck Telescope of the high redshift z=1.824 aligned radio galaxy 3C256. Our observations confirm that the spatially extended UV continuum emission from this galaxy is…
From optical spectropolarimetry of Cygnus A we conclude that the scattering medium in the ionization cones in Cygnus A is moving outward at a speed of 170+-34 km/s, and that the required momentum can be supplied by the radiation pressure of…
Observations of quasars show that the polarization position angle of the emission coming from them varies greatly over time, including periods called rotations during which the angle changes in an orderly manner. The study proposes a method…