Related papers: SDSS J1138+3517: A quasar showing remarkably varia…
We study high-resolution spectra of the `overlapping-trough' low-ionization broad absorption line (LoBAL) quasar SDSS J030000.56+004828.0. The CaII, MgII and MgI column densities in this object are the largest reported to date for any BAL…
We observed the Seyfert 1 galaxy NGC 3516 with the Goddard High Resolution Spectrograph on the Hubble Space Telescope, and obtained UV spectra at a resolution of about 20,000 in the redshifted C IV 1549 region. The intrinsic C IV absorption…
We here report an identification of SDSS J090152.04+624342.6 as a new "overlapping-trough" iron low-ionization broad absorption line quasar at redshift of $z\sim2.1$. No strong variation of the broad absorption lines can be revealed through…
We present deep (9 hours) Gemini-N/GNIRS near-infrared spectroscopic observations of ULAS J1342+0928, a luminous quasar at z=7.54. Various broad emission lines were detected, as well as the underlying continuum and iron forests over the…
We analyse the properties of the CIV broad emission line in connection with the X-ray emission of 30 bright SDSS quasars at z~3.0-3.3 with pointed XMM-Newton observations, which were selected to test the suitability of AGN as cosmological…
(Modified) We study the abundance of silicon in the intergalactic medium by analyzing the statistics of SiIV, CIV, and HI pixel optical depths in a sample of 19 high-quality quasar absorption spectra spanning redshifts z ~ 2 - 4, which we…
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 search 149 moderate resolution background quasar spectra, from Gemini, Keck, the MMT,…
(Abridged) With the goal of investigating the nature of OVI absorbers at high redshifts, we study the effects of proximity to the background quasar. In a sample of sixteen quasars at z(QSO) between 2.14 and 2.87 observed at 6.6 km/s…
Aims. We have searched for temporal variations of narrow absorption lines in high resolution quasar spectra. A sample of 5 distant sources have been assembled, for which 2 spectra - VLT/UVES or Keck/HIRES - taken several years apart are…
Spectropolarimetry of Broad Absorption Line Quasars (BALQSO's) has demonstrated that the geometry of the absorbing material is far from spherically symmetric. Calculations of accretion disk spectra suggest that the intrinsic radiation…
Spectra of the z_em = 3.268 quasar PKS 2126-158 have been obtained in the range lambda lambda 4300-6620 A with a resolution R = 27000 and an average signal-to-noise ratio s/n = 25 per resolution element. The list of the identified…
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 ~…
Context: A significantly higher incidence of strong (rest equivalent width W_r > 1 {\AA}) intervening Mg II absorption is observed along gamma-ray burst (GRB) sight-lines relative to those of quasar sight-lines. A geometrical explanation…
We present the analysis of multi-wavelength observations of bright quasar HS1603+3820: the optical data taken with the MMT and Keck telescopes, and X-ray data obtained with the Chandra X-ray Observatory. The optical spectra contain a very…
The nature of the galaxies that give rise to absorption lines, such as damped Lyman-alpha systems (DLAs) or strong MgII lines, in quasar spectra is difficult to investigate in emission. Taking advantage of the total absorption of the QSO…
In the manuscript, the blue quasar SDSS J105816.19+544310.2 (=SDSS J1058+5443) at redshift 0.479 is reported as so-far the best candidate of true type-2 quasar with disappearance of central BLRs. There are so-far no definite conclusions on…
We present an investigation of the rest-frame optical/UV and X-ray properties for a sample of 3027 X-ray selected quasars between $1.5 \leq z \leq 3.5$ detected in the deepest Spectrum Roentgen Gamma/eROSITA data available and observed by…
The accretion of interstellar medium onto the central super massive black holes is widely accepted as the source of the gigantic energy released by the active galactic nuclei. But few pieces of observational evidence have been confirmed…
We present the observations of a weak MgII absorption system detected at z~0.452 in the UVES high resolution spectrum of the QSO HE0001-2340. The weaker of the two MgII components forming the system shows associated absorptions due to SiI,…
We present multiple spectropolarimetric observations of the nearby Type Ia supernova SN 2011fe in M101, obtained before, during, and after the time of maximum apparent visual brightness. SN 2011fe exhibits time-dependent polarization in…