Related papers: The QSO proximity effect at redshift <z>=2.6 with …
We discuss broad- and narrow-band imaging of 7 arcmin fields of 14 QSOs with redshift ~1.1. The narrow-band filters were chosen to detect redshifted [O II] 3727A, and the broad bands are R and I, which correspond to rest wavelengths…
Bright, high redshift ($z>6$) QSOs are powerful probes of the ionisation state of the intervening intergalactic medium (IGM). The detection of Ly$\alpha$ damping wing absorption imprinted in the spectrum of high-z QSOs can provide strong…
We aim to place new, strengthened constraints on the luminosity function (LF) of H-alpha emitting galaxies at redshift z=2.2, and to further constrain the instantaneous star-formation rate density of the universe (rho*). We have used the…
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…
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 have measured the distribution function of the flux decrement caused by Lyman alpha forest absorption in a new sample of high resolution QSO spectra. The observations are compared to the results from two simulations of the Lya forest: an…
The Lyman-alpha forest has opened a new redshift regime for cosmological investigation. At z > 2 it provides a unique probe of cosmic geometry and an independent constraint on dark energy that is not subject to standard candle or ruler…
We measure the large-scale cross-correlation of quasars with the Lyman \alpha\ forest absorption in redshift space, using ~ 60000 quasar spectra from Data Release 9 (DR9) of the Baryon Oscillation Spectroscopic Survey (BOSS). The…
In this paper we present Monte-Carlo simulations of Lyman alpha absorption systems which originate in galactic haloes, galaxy discs and dark matter (DM) satellites around big central haloes. It is found that for strong Lyman alpha…
We have measured the bias of QSOs as a function of QSO luminosity at fixed redshift (z<1) by cross-correlating them with LRGs in the same spatial volume, hence breaking the degeneracy between QSO luminosity and redshift. We use three QSO…
We present the results of an infrared survey of QSO fields at z=0.95, 0.995 and 1.5. Each z<1 field was imaged to typical continuum limits of J=20.5, Kprime=19 (5 sigma), and line fluxes of 1.3E10{-16}ergs/cm^2/s (1 sigma)in a 1%…
We present FUSE observations of the HeII Lyman alpha forest in the redshift range 2.3 < z < 2.7 towards HS1700+6416. Between October 2002 and February 2003, the brightness of the QSO increased by a factor 2. Therefore, with an exposure time…
A sample of 8 QSOs with 1.7 < z_em < 3.7 has been observed with VLT/UVES at a typical resolution 45000 and S/N~40-50. Thanks to the two-arm design of the spectrograph, a remarkable efficiency has been achieved below 400nm and above 800nm,…
We obtained spectra of 60 red, starlike objects (E< 18.8) identified with FIRST radio sources, S_{1.4GHz} > 1 mJy. Eight are QSOs with redshift z> 3.6.Combined with our pilot search (Benn et al 2002), our sample of 121 candidates yields a…
We present results for QSO PKS 0405-123 (z=0.574, V=14.9), as part of a STIS Investigation Definition Team (IDT) key project to study weak Ly-alpha forest systems at low z. We detect 59 (47) Ly-alpha absorbers at 4.0 sigma significance to…
We performed a search for the HeH+ J=1-0 line (\nu_{rest} = 2010.183873 GHz) and simultaneously for the CH ^2\Pi_{3/2}(F_2)J=3/2 - ^2\Pi_{1/2}(F_2)J=1/2 lines (\nu_{rest}\approx 2006.8 and 2010.8 GHz) toward one of the highest-redshift…
We investigate the clustering properties of 13 QSO lines of sight in flat space, with average redshifts from z~2 to 4. We estimate the 1-D power spectrum and the integral density of neighbours, and discuss their variation with respect to…
Three high-redshift (z=2) and high luminosity (M_B < -28 mag for Ho = 50, qo=0.5) QSOs, two radio-quiet one radio-loud, were imaged in R, I and K bands. The luminosities, colours and sizes of the hosts overlap with those of actively…
The properties of the Lyman-$\alpha$ absorptions observed in the spectra of QSOs are reviewed: the distribution of column densities and Doppler widths, the redshift evolution, the ``inverse effect'', the clustering. By interpreting the…
Combining a new, increased dataset of 8 QSOs covering the Ly-alpha forest at redshifts 1.5 < z < 3.6 from VLT/UVES observations with previously published results, we have investigated the properties of the Ly-alpha forest at 1.5 < z < 4. We…