相关论文: Highly ionized absorbers at high redshift

We search for OVI absorption in a Keck HIRES spectrum of the z=3.62 quasar Q1422+231. Comparison of CIV measurements to cosmological simulations shows that \lya forest absorbers with N_HI > 10^{14.5} have [C/H]~=-2.5, for the UV background…

We present a direct measurement of the metallicity distribution function for the high redshift intergalactic medium. We determine the shape of this function using survival statistics, which account for both detections and non-detections of…

We have obtained new observations of the partial Lyman limit absorber at \zabs$=0.93$ towards quasar PG~1206+459, and revisit its chemical and physical conditions. The absorber, with $ N(HI) \sim 10^{17.0}$ ~\sqcm\ and absorption lines…

We report the results of a survey of OVI 1032 absorption along the lines of sight to 25 white dwarfs in the local interstellar medium (LISM) obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). We find that interstellar OVI…

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…

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…

Using high resolution, high signal-to-noise ultraviolet spectra of the z = 0.9754 quasar PG1148+549 obtained with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope, we study the physical conditions and abundances of…

We present a study of OVI-bearing gas around 247 low-mass (median log(M*/Msun)~8.7) galaxies at low redshifts (0.1 < z < 0.7) using background quasars as part of the MUSE Quasar-fields Blind Emitters Survey (MUSEQuBES). We find that the…

FUV echelle spectroscopy of the radio-quiet QSO H1821+643 (z = 0.297), obtained with the Space Telescope Imaging Spectrograph (STIS) at 7 km/s resolution, reveals 4 definite O VI absorption line systems and one probable O VI absorber at…

We present observations of the O VI system at z_abs = 0.495096 toward PKS 0405-123 (z_em = 0.5726) obtained with FUSE and STIS. In addition to strong O VI, with log N(O VI) = 14.47+/-0.02, and moderate H I this absorber shows C III, N IV, O…

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…

The observed intergalactic OVI absorbers at z>0 have been regarded as a significant reservoir of the ``missing baryons''. However, to fully understand how these absorbers contribute to the baryon inventory, it is crucial to determine…

We use high spectral resolution (R=45000) and high signal-to-noise ratio (S/N \~ 35-70 per pixel) spectra of 19 high-redshift (2.1<z_em<3.2) quasars to investigate the metal content of the low-density intergalactic medium using…

We have investigated the distribution and evolution of ~3100 intergalactic HI absorbers with HI column densities log N(HI) = [12.75, 17.0] at 1.9 < z < 3.2, using 18 high resolution, high S/N quasar spectra obtained from the ESO VLT/UVES…

We report the results of a systematic search for signatures of metal lines in quasar spectra of the Sloan Digital Sky Survey (SDSS) Data Release 3(DR3), focusing on finding intervening absorbers via detection of their OVI doublet. Here we…

We present the results of observations taken with the X-shooter spectrograph devoted to the study of quasars at z ~ 6. This paper focuses on the properties of metals at high redshift traced, in particular, by the C IV doublet absorption…

We present the first results from our NASA Keck Observatory Database of Ionized Absorbers toward Quasars (KODIAQ) survey which aims to characterize the properties of the highly ionized gas of high redshift galaxies and their circumgalactic…

STIS Echelle observations at a resolution of 10 km/s and UVES/VLT spectroscopy at a resolution of 7 km/s of the luminous QSO HE 0515-4414 (z_em = 1.73, B = 15.0) reveal four intervening O VI absorption systems in the redshift range 1.2 <…

We present the analysis of five O VI absorbers identified across a redshift path of z $\sim (0.6 - 1.3)$ towards the background quasar PG $1522+101$ with information on five consecutive ionization stages of oxygen from O II to O VI. The…

We have studied the abundance of oxygen in the IGM by analyzing OVI, CIV, SiIV, and HI pixel optical depths derived from a set of high-quality VLT and Keck spectra of 17 QSOs at 2.1 < z < 3.6. Comparing OVI and CIV optical depth ratios to…