TY - JOUR
T1 - The low-redshift Lyα forest toward PKS 0405-123
AU - Williger, Gerard M.
AU - Heap, Sara R.
AU - Weymann, Ray J.
AU - Davé, Romeel
AU - Ellingson, Erica
AU - Carswell, Robert F.
AU - Tripp, Todd M.
AU - Jenkins, Edward B.
PY - 2006/1/10
Y1 - 2006/1/10
N2 - We present results for Lyα forest and metal absorbers from ∼7 km s-1 resolution Space Telescope Imaging Spectrograph data for QSO PKS 0405-123 (z = 0.574). We analyze strong and weak samples of Lyα forest lines, containing 60 absorbers with column density log NH1 ≥ 13.3 over 0.002 < z < 0.423 and 44 with log NH1 ≥ 13.1 over 0.020 < z < 0.234, respectively. Seven absorbers contain metals, all with associated O VI and often offset in velocity from Lyα. The strong and weak Doppler parameter distributions have 〈b〉 = 41 ± 22 and 44 ± 21 km s-1, respectively. Simulated spectra suggest that line blending and signal-to-noise ratio effects inflate b. For absorbers with 13.1 < log NHI, < 14.0, we find a redshift overdensity of ∼0.2-0.3 dex at 0.127 < z < 0.234, which we attribute to cosmic variance. There is a void in the strong sample at 0.0320 < z < 0.0814 with probability of random occurrence P < 0.0004. We detect Lyα-Lyα clustering in our sample on a scale of Δv ≤ 250 km s -1 for log NHI ≥ 13.3, consistent with a numerical model of structure evolution. We detect velocity correlations of up to 250 km s-1 between Lya absorbers and 39 galaxies at z < 0.43 out to a transverse distance of 1.6 h70-1 local frame Mpc. The Lyα-galaxy two-point correlation function is significant out to Δv < 250 km s-1 and grows with minimum H I column density. The strongest signal occurs for log NHI ≳ 13.5-14.0 absorbers and is similar to the galaxy-galaxy correlation, implying that such Lyα absorbers have masses log(M/MȮ) = 11.3 -0.6+1.0. We find a correlation between local galaxy counts and local summed H I column density, with peak significance on scales of 4000-6000 km s-1 and probability of random occurrence P = 0.0009. Finally, we present column densities for a number of Galactic species.
AB - We present results for Lyα forest and metal absorbers from ∼7 km s-1 resolution Space Telescope Imaging Spectrograph data for QSO PKS 0405-123 (z = 0.574). We analyze strong and weak samples of Lyα forest lines, containing 60 absorbers with column density log NH1 ≥ 13.3 over 0.002 < z < 0.423 and 44 with log NH1 ≥ 13.1 over 0.020 < z < 0.234, respectively. Seven absorbers contain metals, all with associated O VI and often offset in velocity from Lyα. The strong and weak Doppler parameter distributions have 〈b〉 = 41 ± 22 and 44 ± 21 km s-1, respectively. Simulated spectra suggest that line blending and signal-to-noise ratio effects inflate b. For absorbers with 13.1 < log NHI, < 14.0, we find a redshift overdensity of ∼0.2-0.3 dex at 0.127 < z < 0.234, which we attribute to cosmic variance. There is a void in the strong sample at 0.0320 < z < 0.0814 with probability of random occurrence P < 0.0004. We detect Lyα-Lyα clustering in our sample on a scale of Δv ≤ 250 km s -1 for log NHI ≥ 13.3, consistent with a numerical model of structure evolution. We detect velocity correlations of up to 250 km s-1 between Lya absorbers and 39 galaxies at z < 0.43 out to a transverse distance of 1.6 h70-1 local frame Mpc. The Lyα-galaxy two-point correlation function is significant out to Δv < 250 km s-1 and grows with minimum H I column density. The strongest signal occurs for log NHI ≳ 13.5-14.0 absorbers and is similar to the galaxy-galaxy correlation, implying that such Lyα absorbers have masses log(M/MȮ) = 11.3 -0.6+1.0. We find a correlation between local galaxy counts and local summed H I column density, with peak significance on scales of 4000-6000 km s-1 and probability of random occurrence P = 0.0009. Finally, we present column densities for a number of Galactic species.
KW - Cosmology: observations
KW - Intergalactic medium
KW - Quasars: absorption lines
UR - http://www.scopus.com/inward/record.url?scp=32044467398&partnerID=8YFLogxK
U2 - 10.1086/498127
DO - 10.1086/498127
M3 - Article
AN - SCOPUS:32044467398
VL - 636
SP - 631
EP - 653
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2 I
ER -