THE RELATIONSHIP BETWEEN INTERGALACTIC H I/O VI AND NEARBY (z < 0.017) GALAXIES

Journal Article · Fri May 15 04:00:00 EDT 2009 · Astrophysical Journal, Supplement Series

DOI:https://doi.org/10.1088/0067-0049/182/1/378; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21269158

Wakker, B P; Savage, B D ^[1]

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1. Department of Astronomy, University of Wisconsin, 475 N. Charter St, Madison, WI 53706 (United States)

We analyze intergalactic H I and O VI absorbers with v < 5000 km s{sup -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 ({rho}) and velocity difference ({delta}v), as well as the fraction of galaxies with an absorber closer than a given {rho} and {delta}v. We identify possible 'void absorbers' ({rho} > 3 Mpc to the nearest L{sub *} galaxy), although at v < 2500 km s{sup -1} all absorbers are within 1.5 Mpc of an L>0.1 L{sub *} galaxy. The absorber properties depend on {rho}, but the relations are not simple correlations. For four absorbers with {rho} = 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 {rho} < 350 kpc, the covering factor of Ly{alpha} (O VI) around L>0.1 L {sub *} galaxies is 100% (70%) for field galaxies and 65% (10%) for group galaxies; 50% of galaxy groups have associated Ly{alpha}. All O VI absorbers occur within 550 kpc of an L>0.25 L{sub *} 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{alpha} lines increases from z = 3 to z = 0 and with decreasing impact parameter, consistent with the idea that gas inside {approx}500 kpc from galaxies is heating up, although alternative explanations cannot be clearly excluded.

• OSTI ID: 21269158
• Journal Information: Astrophysical Journal, Supplement Series, Journal Name: Astrophysical Journal, Supplement Series Journal Issue: 1 Vol. 182; ISSN 0067-0049; ISSN APJSA2
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
99 GENERAL AND MISCELLANEOUS
ABSORPTION
BARYONS
CORRELATIONS
FAR ULTRAVIOLET RADIATION
GALACTIC EVOLUTION
GALAXIES
IMPACT PARAMETER
LUMINOSITY
PHOTOIONIZATION
ROTATION
TELESCOPES
VELOCITY