TY - JOUR
T1 - Probing the intergalactic medium/galaxy connection. V. on the origin of Lyα and O VI absorption at z < 0.2
AU - Prochaska, J. Xavier
AU - Weiner, B.
AU - Chen, H. W.
AU - Mulchaey, J.
AU - Cooksey, K.
PY - 2011/10/20
Y1 - 2011/10/20
N2 - We analyze the association of galaxies with Lyα and O VI absorption, the most commonly detected transitions of the low-z intergalactic medium (IGM), in the fields of 14 quasars with z em = 0.06-0.57. Confirming previous studies, we observe a high covering fraction for Lyα absorption to impact parameter ρ = 300h -1 72kpc: 33/37 of our L > 0.01 L* galaxies show Lyα equivalent width W Lyα ≥ 50m. Galaxies of all luminosity L > 0.01 L* and spectral type are surrounded by a diffuse and ionized circumgalactic medium (CGM), whose baryonic mass is estimated at ∼1010.5±0.3 M ⊙ for a constant N H = 1019 cm -2. The virialized halos and extended CGM of present-day galaxies are responsible for most strong Lyα absorbers (W Lyα > 300m) but cannot reproduce the majority of observed lines in the Lyα forest. We conclude that the majority of Lyα absorption with W Lyα = 30-300m occurs in the cosmic web predicted by cosmological simulations and estimate a characteristic width for these filaments of 400h -1 72kpc. Regarding O VI, we observe a near unity covering fraction to ρ = 200h -1 72kpc for L > 0.1 L* galaxies and to ρ = 300h -1 72kpc for sub-L* (0.1 L* < L < L*) galaxies. Similar to our Lyα results, stronger O VI systems (W 1031 > 70m) arise in the virialized halos of L > 0.1 L* galaxies. Unlike Lyα, the weaker O VI systems (W 1031 30m) arise in the extended CGM of sub-L* galaxies. The majority of O VI gas observed in the low-z IGM is associated with a diffuse medium surrounding individual galaxies with L 0.3 L* and rarely originates in the so-called warm-hot IGM (predicted by cosmological simulations.
AB - We analyze the association of galaxies with Lyα and O VI absorption, the most commonly detected transitions of the low-z intergalactic medium (IGM), in the fields of 14 quasars with z em = 0.06-0.57. Confirming previous studies, we observe a high covering fraction for Lyα absorption to impact parameter ρ = 300h -1 72kpc: 33/37 of our L > 0.01 L* galaxies show Lyα equivalent width W Lyα ≥ 50m. Galaxies of all luminosity L > 0.01 L* and spectral type are surrounded by a diffuse and ionized circumgalactic medium (CGM), whose baryonic mass is estimated at ∼1010.5±0.3 M ⊙ for a constant N H = 1019 cm -2. The virialized halos and extended CGM of present-day galaxies are responsible for most strong Lyα absorbers (W Lyα > 300m) but cannot reproduce the majority of observed lines in the Lyα forest. We conclude that the majority of Lyα absorption with W Lyα = 30-300m occurs in the cosmic web predicted by cosmological simulations and estimate a characteristic width for these filaments of 400h -1 72kpc. Regarding O VI, we observe a near unity covering fraction to ρ = 200h -1 72kpc for L > 0.1 L* galaxies and to ρ = 300h -1 72kpc for sub-L* (0.1 L* < L < L*) galaxies. Similar to our Lyα results, stronger O VI systems (W 1031 > 70m) arise in the virialized halos of L > 0.1 L* galaxies. Unlike Lyα, the weaker O VI systems (W 1031 30m) arise in the extended CGM of sub-L* galaxies. The majority of O VI gas observed in the low-z IGM is associated with a diffuse medium surrounding individual galaxies with L 0.3 L* and rarely originates in the so-called warm-hot IGM (predicted by cosmological simulations.
KW - galaxies: structure
KW - intergalactic medium
KW - large-scale structure of universe
KW - quasars: absorption lines
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U2 - 10.1088/0004-637X/740/2/91
DO - 10.1088/0004-637X/740/2/91
M3 - Article
AN - SCOPUS:80053944238
VL - 740
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 91
ER -