Related papers: Radiation-pressure Waves and Multiphase Quasar Out…

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…

In this paper, we provide new 1 Ms $Chandra$ ACIS spectra of two quasars in the Chandra Deep Field South (CDF-S), which were previously reported to show strong and extremely blueshifted X-ray emission/absorption line features in previous 1…

Line locking (LL) of absorption line systems is a clear signature of the dynamical importance of radiation pressure force in driving astrophysical flows, with recent findings suggesting that it may be common in quasars exhibiting multiple…

As one of the most luminous radio-loud quasars showing intrinsic ultraviolet (UV) and X-ray absorption, 3C 351 provides a laboratory for studying the kinematics and physical conditions of such ionized absorbers. We present an analysis of…

We employ detailed photoionization models to infer the physical conditions of intrinsic narrow absorption line systems found in high resolution spectra of three quasars at z=2.6-3.0. We focus on a family of intrinsic absorbers characterized…

Absorption-line spectroscopy of 23 background QSOs and numerous background galaxies has let us measure the spatial distribution of metals and neutral hydrogen around 1044 UV-selected galaxies at redshifts 1.8<z<3.3. The typical galaxy is…

We present an improved model for excess variance spectra describing ultra-fast outflows and successfully apply it to the luminous (L ~ 10^47 erg/s) low-redshift (z = 0.184) quasar PDS 456. The model is able to account well for the…

We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph onboard the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization…

I Zw 1 is the prototype narrow line quasar. We report here the results of our study of the UV emission of I Zw 1 using a high S/N (50-120) spectrum obtained with the HST FOS. The following main new results are obtained: 1. The Mg II and Al…

Intervening metal absorption lines in the spectra of z > 6 quasars are fundamental probes of the ionization state and chemical composition of circumgalactic and intergalactic gas near the end of the reionization epoch. Large absorber…

We report the results of several programs to study the variability of high-velocity (up to 0.2c) mini-"broad absorption lines" (mini-BALs) and BALs in quasar spectra, and thus to better characterize the structural and physical properties of…

We present Keck/LRIS spectroscopy of seven isolated galaxy-quasar pairs at $0.4 \leq z \leq 0.6$, each exhibiting ultra-strong MgII absorption ($W_{r,2796} \geq 3$ {\AA}), probing both down-the-barrel and transverse gas flows.…

Ultraviolet and X-ray observations show evidence of outflowing gas around many active galactic nuclei. Some of these outflows may be driven off gas infalling towards the central black hole. We perform radiative transfer calculations to…

In Keck HIRES spectra of 9 QSOs we identify a sample of 908 CIV absorber components in 188 systems outside the Lyman forest in the redshift range 1.6 < z < 4.4, with related lines of SiIV, CII, SiII and NV. The properties of the CIV…

Using long-slit optical spectroscopy obtained at the 10.4 m Gran Telescopio Canarias, we have examined the gaseous environment of the radio-loud quasar TXS 1436+157 (z=2.54), previously known to be associated with a large Ly-alpha nebula…

We study the ionization structure of galactic outflows in 37 nearby, star forming galaxies with the Cosmic Origins Spectrograph on the Hubble Space Telescope. We use the O I, Si II, Si III, and Si IV ultraviolet absorption lines to…

We present a catalog of 5039 broad absorption line (BAL) quasars (QSOs) in the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) QSO catalog that have absorption troughs covering a continuous velocity range >= 2000 km/s. We have fit…

Broad absorption line (BAL) quasars exhibit significant outflows, offering insights into active galactic nuclei (AGN) feedback. While typically associated with high Eddington ratios, BAL quasars also occur in low Eddington ratio regimes,…

We conducted a survey of quasar outflows using the VLT/X-shooter spectrograph. When choosing the 14 BAL and mini-BALs comprising this sample, the data did not cover the S IV and S IV* troughs, whose ratio can be used to determine the…

We investigate the dependence on data quality of quasar properties measured from the CIV emission line region at high redshifts. Our measurements come from 32 epochs of Sloan Digital Sky Survey (SDSS) Reverberation Mapping Project…