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2009ApJS..182..378W - Astrophys. J., Suppl. Ser., 182, 378-467 (2009/May-0)

The relationship between intergalactic H I/O VI and nearby (z < 0.017) galaxies.


Abstract (from CDS):

We analyze intergalactic H I and O VI absorbers with v < 5000 km/s 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 (ρ) and velocity difference (Δv), as well as the fraction of galaxies with an absorber closer than a given ρ and Δv. We identify possible "void absorbers" (ρ > 3 Mpc to the nearest L*galaxy), although at v < 2500 km/s all absorbers are within 1.5 Mpc of an L>0.1 L*galaxy. The absorber properties depend on ρ, but the relations are not simple correlations. For four absorbers with ρ = 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 ρ < 350 kpc, the covering factor of Lyα (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 Lyα. 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 Lyα 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.

Abstract Copyright:

Journal keyword(s): galaxies: evolution - galaxies: halos - intergalactic medium - ultraviolet: galaxies

VizieR on-line data: <Available at CDS (J/ApJS/182/378): table1.dat table3.dat table13.dat>

Simbad objects: 77

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