2009/03/12 by B. P. Wakker, B. D. Savage · 4 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Baryon #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy rotation curve #Hubble space telescope #Intergalactic medium #Intergalactic travel #Luminosity #Redshift #Spectral line #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1088/0067-0049/182/1/378
ApJ Supplement, in press
arxiv created 2009/03/12 · openalex publication_date 2009/05/01 · arxiv updated 2015/05/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We analyze intergalactic H i and O vi absorbers with v < 5000 km s -1 in Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer spectra of 76 active galactic nuclei. The baryons traced by H i/O vi absorption are clearly associated with the extended surroundings of galaxies; for impact parameters < 400 kpc they are 2-4 times more numerous as those inside the galaxies. This large reservoir of matter likely plays a major role in galaxy evolution. We tabulate the fraction of absorbers having a galaxy of a given luminosity within a given impact parameter () and velocity difference (v), as well as the fraction of galaxies with an absorber closer than a given and v. We identify possible "void absorbers" ( > 3 Mpc to the nearest L * galaxy), although at v < 2500 km s -1 all absorbers are within 1.5 Mpc of an L > 0.1 L * galaxy. The absorber properties depend on , but the relations are not simple correlations. For four absorbers with = 50-350 kpc from an edge-on galaxy with known orientation of its rotation, we find no clear relation between absorber velocities and the rotation curve of the underlying galaxy. For < 350 kpc, the covering factor of Ly (O vi) around L > 0.1 L * galaxies is 100% (70%) for field galaxies and 65% (10%) for group galaxies; 50% of galaxy groups have associated Ly. All O vi absorbers occur within 550 kpc of an L > 0.25 L * galaxy. The properties of three of 14 O vi absorbers are consistent with photoionization, for five the evidence points to collisional ionization; the others are ambiguous. The fraction of broad Ly lines increases from z = 3 to z = 0 and with decreasing impact parameter, consistent with the idea that gas inside 500 kpc from galaxies is heating up, although alternative explanations cannot be clearly excluded.