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The low-redshift Ly-alpha forest of absorption lines provides a probe of large-scale baryonic structures in the intergalactic medium, some of which may be remnants of physical conditions set up during the epoch of galaxy formation. We discuss our recent Hubble Space Telescope (HST) observations and interpretation of low-z Ly-alpha clouds toward nearby Seyferts and QSOs, including their frequency, space density, estimated mass, association with galaxies, and contribution to Omega-baryon. Our HST/GHRS detections of 70 Ly-alpha absorbers with N_HI > 10^12.6 cm-2 along 11 sightlines covering pathlength Delta(cz) = 114,000 km/s show f(>N_HI) ~ N_HI^{-0.63 +- 0.04} and a line frequency dN/dz = 200 +- 40 for N_HI > 10^12.6 cm-2 (one every 1500 km/s of redshift). A group of strong absorbers toward PKS 2155-304 may be associated with gas (400-800) h_75^-1 kpc from 4 large galaxies, with low metallicity (< 0.003 solar) and D/H < 2 x 10^-4. At low-z, we derive a metagalactic ionizing radiation field from AGN of J_0 = 1.3^{+0.8 -0.5} x 10^-23 ergs/cm2/s/Hz/sr and a Ly-alpha-forest baryon density Omega-baryon = (0.008 +- 0.004) h_75^-1 [J_-23 N_14 b_100]^{1/2} For clouds of characteristic size b = (100 kpc)b_100.
We present a detailed analysis of the intergalactic metal-line absorption systems in the archival HST/STIS and FUSE ultraviolet spectra of the low-redshift quasar PKS1302-102 (z_QSO = 0.2784). We supplement the archive data with CLOUDY ionization mod
We investigate the association between galaxies and metal-enriched and metal-deficient absorbers in the local universe ($z < 0.16$) using a large compilation of FUV spectra of bright AGN targets observed with the Cosmic Origins Spectrograph aboard th
Using the Cosmic Origins Spectrograph aboard the Hubble Space Telescope, we measured the abundances of six ions (C III, C IV, Si III, Si IV, N V, O VI) in the low-redshift (z < 0.4) intergalactic medium and explored C and Si ionization corrections fr
The enrichment of the intergalactic medium (IGM) with heavy elements provides us with a record of past star formation and with an opportunity to study the interactions between galaxies and their environments. We summarize current data analysis method
The distribution of neutral hydrogen in the intergalactic medium (IGM) is currently explored at low-z by means of UV spectroscopy of quasars. We propose an alternative approach based on UV colours of quasars as observed from GALEX surveys. We built a