Related papers: The nature of NV absorbers at high redshift

We present the results from our search for C IV in the intergalactic medium at redshifts z=5.3-6.0. We have observed four z~6 QSOs with Keck/NIRSPEC in echelle mode. The data are the most sensitive yet taken to search for C IV at these…

We present a detailed analysis of 99 optically thin C III absorption systems at redshift, $0.2 \le z \le 0.9$ associated with neutral hydrogen column densities in the range, $15 \le {\rm log}$ $N_{\rm H\,I}$ ($cm^{-2}$) $\le 16.2$. Using…

We present HST spectra for a sample of six QSOs with intermediate redshift (z_a < 1) damped Ly-alpha systems. These observations aim at measuring the HI column density and detect metal lines in order to investigate the metal enrichment of…

We present a new method for probing the physical conditions and metal enrichment of the Intergalactic Medium: the composite spectrum of Ly-alpha forest absorbers. We apply this technique to a sample of 9480 Ly-alpha absorbers with redshift…

We have vastly increased the CIV statistics at intermediate redshift by surveying the thousands of quasars in the Sloan Digital Sky Survey Data-Release 7. We visually verified over 16,000 CIV systems with 1.46 < z < 4.55---a sample size…

We use a large sample of galaxies at z~3 to establish a relationship between reddening, neutral gas covering fraction (fcov(HI)), and the escape of ionizing photons at high redshift. Our sample includes 933 galaxies at z~3, 121 of which…

Intergalactic absorbers along lines of sight to distant quasars are a powerful diagnostic for the evolution and content of the intergalactic medium (IGM). In this study, we use the FUSE satellite to search 129 known lya absorption systems…

We present the results of the X-ray spectral analysis of an XMM-Newton-selected type II QSO sample with z>0.5 and 0.5-10 keV flux of 0.3-33 x 10^{-14} erg/s/cm^2. The distribution of absorbing column densities in type II QSOs is…

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…

We explore the effects of UV absorbing material on the shape of the EUV continuum radiation emitted by the active galactic nucleus, and on the relative strengths of emission lines, formed in the narrow line regions of Seyfert galaxies,…

We have analyzed the properties of metals in the high redshift intergalactic medium using a novel objective pixel optical depth technique on a sample of extremely high signal-to-noise Keck HIRES and ESI spectra of 26 quasars between…

We present high resolution radio data at 3.5 and 20 cm from the VLA in the A configuration for 144 quasars with known CIV absorption line properties. Using these measurements, we compare and contrast a number of quasar orientation…

We present a survey for metal absorption systems traced by neutral oxygen over $3.2 < z < 6.5$. Our survey uses Keck/ESI and VLT/X-Shooter spectra of 199 QSOs with redshifts up to 6.6. In total we detect 74 O I absorbers, of which 57 are…

To investigate the evolution of metal-enriched gas over recent cosmic epochs as well as to characterize the diffuse, ionized, metal-enriched circumgalactic medium (CGM), we have conducted a blind survey for C IV absorption systems in 89 QSO…

We present a statistical analysis of the associated, high ionization narrow absorption line (NAL) systems in a sample of 59 QSOs defined from the HST QSO Absorption Line Key Project. We have compiled the QSO luminosities at 2500 A, 5 GHz,…

We present HST and FUSE observations of the intergalactic absorption toward PG1116+215 in the 900-3000 A spectral region. We detect 25 Ly-alpha absorbers at rest-frame equivalent widths W_r > 30 mA, yielding (dN/dz)_Ly-alpha = 154+/-18 over…

We present the results of photoionization modeling of nine weak MgII (W_r<0.3 Ang) quasar absorption line systems with redshifts 1.4<z<2.4 obtained with the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. These…

The intrinsic column density (NH) distribution of quasars is poorly known. At the high obscuration end of the quasar population and for redshifts z<1, the X-ray spectra can only be reliably characterized using broad-band measurements which…

We report the near-IR detection of a prominent CIV absorption in the rest-frame UV spectrum of the most distant known QSO, SDSS J104433.04-012502.2, at z=5.80. This QSO was recently observed with XMM-Newton and it was found to be notably…

The total amount of OVI present in the interstellar medium (ISM) obtained via absorption measurements in UV and X-ray spectra is currently in disagreement, with the latter being significantly larger (by a factor of 10 or more) than the…