[79.01] The Statistical Relationship Between Low-$z$ Ly$\alpha$ Absorbers and Galaxies

AAS 204th Meeting, June 2004
Session 79 Intergalactic Gas
Poster, Thursday, June 3, 2004, 9:20am-4:00pm, Ballroom

[79.01] The Statistical Relationship Between Low-z Ly\alpha Absorbers and Galaxies

S. V. Penton, J. T. Stocke, J. M. Shull (University of Colorado, Boulder)

We present the results of 30 low-z HST sightlines in an exploration of the very local (z < 0.07, cz < 21,000 km s^-1) Ly\alpha forest and its relationship to the known galaxy distribution. Together, these STIS+GHRS medium resolution observations sample 347,000 km s^-1 (z=1.16) of the local universe, of which about half represent pathlength through galaxy voids. We will explore the distribution of the detected Ly\alpha absorbers in these sightlines in terms of void statistics, the two-point correlation function (TPCF) along individual sightlines, and nearest galaxy neighbor statistics (based upon the March 2004 CfA redshift catalogue). We find that the stronger absorbers in our sample (N_HI > 10¹³ cm^-2) have nearest neighbor distances more like bright galaxies (median distance ~0.4 h₇₀^-1 Mpc), while the weaker absorbers show much larger nearest neighbor distances (median distance ~1 h₇₀^-1 Mpc). The TPCFs indicate that the stronger absorbers cluster much more strongly than the weaker absorbers, but not as strong as galaxies cluster with galaxies. The detected Ly\alpha clouds represent 29 ± 4 % of all baryons at z=0.

This work is based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract No. NAS5-26555. This research was supported by HST guest observer grant GO-06593.01-95A, and by the HST/COS project (NAS5-98043).

The author(s) of this abstract have provided an email address for comments about the abstract: spenton@casa.colorado.edu

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