相关论文: Fluctuations of the intergalactic UV background to…

We present new high-resolution (R~14,000) spectra of the two brightest HeII-transparent quasars in the far-UV (FUV) at z>3.5, HE2QSJ2311-1417 (z=3.70) and HE2QSJ1630+0435 (z=3.81), obtained with the Cosmic Origins Spectrograph (COS) on the…

We present high S/N measurements of the H I Ly alpha absorption line toward 16 Galactic targets which are at distances between approximately 190 and 2200 pc, all beyond the wall of the Local Bubble. We describe the models used to remove…

We report the detection, based on HST and Keck data, of two peculiar absorbers in the Ly-alpha forest of the quasar PKS 0454+039. These clouds, at redshifts z=0.6248 and 0.9315 respectively, display both MgII and FeII absorption lines in…

Using cosmological hydrodynamic simulations of the LCDM model, we present a comparison between the simulation sample and real data sample of HI and HeII Ly\alpha transmitted flux in the absorption spectra of the QSO HE2347-4342. The LCDM…

We present results from high resolution (R\simeq 28000) spectra of six high- redshift QSOs taken at the ESO NTT telescope that allow the detailed study of the Ly-alpha population in the redshift interval z=2.8-4.1. The typical Doppler…

Quasar outflows are fundamental components of quasar environments that might play an important role in feedback to galaxy evolution. We report on the emergence of a remarkable new outflow absorption-line system in the quasar PG1411+442…

We report ultraviolet spectra of the high-redshift (z_em = 2.9) quasar, HE 2347-4342, taken by the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). Spectra in the G130M (medium-resolution, 1135-1440 A) and G140L…

We report on observations of redshifted HeII 304 A absorption in the QSO HE 2347-4342 (z=2.885, V=16.1) with the GHRS on board HST (FWHM=0.7 A). At the expected position of HeII 304 A absorption, HE 2347-4342 is the most UV-bright high…

The estimate of the ionizing UV background through the proximity effect analysis is discussed. Taking into account the correct bending of the column density distribution which appears in high resolution high s/n data, a value of the UV…

X-ray spectra of a significant fraction of cooling flow (CF) clusters of galaxies indicate the presence of a large column of ``cold'' absorbing gas. The physical nature of the absorbing medium remains a mystery. Searches for H I absorption…

Interstellar reddening corrections are necessary to reconstruct the intrinsic spectral energy distributions (SEDs) of accreting protostellar systems. The stellar SED determines the heating and chemical processes that can occur in…

We report the discovery of two damped Ly-alpha absorption-line systems (DLAs) near redshift z=1 along a single quasar sightline (Q1727+5302) with neutral hydrogen column densities of N(HI) = (1.45\pm0.15)\times10^{21} and…

A new molecular hydrogen cloud is found in the sub-damped Ly-alpha absorber [log N(HI)=19.88+/-0.05] at the redshift z=1.15 toward the bright quasar HE0515-4414 (zem = 1.71). More than 30 absorption features in the Lyman band system of H2…

We provide an analytical description of the line broadening of HI absorbers in the Lyman-alpha forest resulting from Doppler broadening and Jeans smoothing. We demonstrate that our relation captures the dependence of the line-width on…

We present high-resolution (FWHM ~ 0.3-1.5 km/s) spectra of interstellar Ca I absorption toward 30 Galactic stars. Comparisons of the column densities of Ca I, Ca II, K I, and other species -- for individual components identified in the…

We interpret observations of intergalactic low ionisation metal absorption systems at redshifts z $\gtrsim$5 in terms of pressure-confined clouds. We find clouds confined by the expected pressure of galactic haloes with masses $11<\log…

We present a spectroscopic investigation with VLT/X-shooter of seven candidate extremely strong damped Lyman-$\alpha$ absorption systems (ESDLAs, $N(\text{HI})\ge 5\times 10^{21}$ cm$^{-2}$) observed along quasar sightlines. We confirm the…

Using the high dispersion NUV mode of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST) to observe Eta Carinae, we have resolved and identified over 500 sharp, circumstellar absorption lines of…

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 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…