Related papers: Probing ~100 AU Intergalactic MgII Absorbing "Clou…
Using deep (11.2hr) VLT/MUSE data from the MEGAFLOW survey, we report the first detection of extended MgII emission from a galaxy's halo that is probed by a quasar sightline. The MgII $\lambda\lambda$ 2796,2803 emission around the $z =…
We show that invaluable information on the structure of quasar outflows can be obtained by considering microlensing (ML) induced variability of absorption line troughs in lensed quasars. Depending on the structure and geometry of the…
The metal line profiles of different ions observed in high HI column density systems [N(HI) > 10^{16} cm^{-2}] in quasar spectra can be used to constrain the ionization structure and kinematic characteristics of the absorbers. For these…
The properties of circum-galactic gas in the halo of quasar host galaxies are investigated analyzing Mg II 2800 and C IV 1540 absorption-line systems along the line of sight close to quasars. We used optical spectroscopy of closely aligned…
We survey the incidence and absorption strength of the metal-line transitions CII 1334 and CIV from the circumgalactic medium (CGM) surrounding z~2 quasars, which act as signposts for massive dark matter halos M_halo~10^12.5 Msun. On scales…
Water masers have been observed in several high redshift active galactic nuclei, including the gravitationally lensed quasar MG 0414+0534. This quasar is lensed into four images, and the water maser is detected in two of them. The…
Our galaxy is the nearest known quasar absorption line system, and it uniquely provides us with an opportunity to probe multiple lines of sight through the same galaxy. This is essential for our interpretations of the complex kinematic…
Background quasars are potentially sensitive probes of galactic outflows provided that one can determine the origin of the absorbing material since both gaseous disks and strong bipolar outflows can contribute to the absorption…
We present new mid-IR observations of the quadruply lensed quasar Q2237+0305 taken with CanariCam on the Gran Telescopio Canarias. Mid-IR emission by hot dust, unlike the optical and near-IR emission from the accretion disk, is unaffected…
We present new MUSE observations of a galaxy group probed by a background quasar. The quasar sightline passes between multiple $z=0.28$ galaxies, whilst showing at the same redshift low ionised metal line species, including Ca II, Mg I, Mg…
Gravitational microlensing of quasars by stars in external galaxies can introduce fluctuations in the centroid of the ``point-like'' macro--images. The induced shifts are extremely small, on micro--arcsecond scales, below the limits of…
Using the MEGAFLOW survey, which consists of a combination of MUSE and UVES observations of 22 quasar fields selected to contain strong MgII absorbers, we measure covering fractions of CIV and MgII as a function of impact parameter $b$…
Lensed quasars are powerful cosmic laboratories; they are used to simultaneously probe various astrophysical phenomena. Microlensing by stars within distant galaxies acts as strong gravitational lenses of multiply imaged quasars, and…
We present a measurement of the cross-correlation of MgII absorption and massive galaxies, using the DR11 main galaxy sample of the Baryon Oscillation Spectroscopic Survey of SDSS-III (CMASS galaxies), and the DR7 quasar spectra of SDSS-II.…
The upcoming ByCycle project on the VISTA/4MOST multi-object spectrograph will offer new prospects of using a massive sample of $\sim 1$ million high spectral resolution ($R$ = 20,000) background quasars to map the circumgalactic metal…
Quasar absorption lines provide detailed information on the chemical, kinematic, and ionization conditions in galaxies and their environments, and provide a means for studying the evolution of these conditions back to the epoch of the first…
We present narrowband images of the gravitational lens system Q~2237+0305 made with the Nordic Optical Telescope in eight different filters covering the wavelength interval 3510-8130 \AA. Using point-spread function photometry fitting we…
The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar as a function of wavelength; this provides…
The neutral hydrogen and the ionized helium absorption in the spectra of quasars are unique probes of structure in the early universe. We present Far-Ultraviolet Spectroscopic Explorer observations of the line of sight to the quasar…
We report the discovery of a further line of sight allowing detection of HeII Ly alpha absorption by the intergalactic medium. A HST/STIS survey of 32 bright z ~ 3 quasars selected from the Hamburg Quasar Surveys yielded one detection…