AAS Meeting #193 - Austin, Texas, January 1999
Session 85. Intergalactic Medium
Oral, Friday, January 8, 1999, 10:00-11:30am, Room 10 (B)

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[85.01] Galaxy Selection and the Lyman Alpha Absorption Properties of Galaxies

S. M. Linder (Penn State Univesity)

It has been shown, using simulations, that the majority of Ly\alpha absorbers at low redshift may arise in low surface brightness galaxies (Linder 1998, ApJ, 495, 637). The simulated galaxy population is 'observed' using selection criteria similar to those of observational surveys. I show that it will be difficult for an observer to determine the correct relationship between absorbers and galaxies or to learn about the absorption properties of galaxies which are typically not found due to observational selection effects. An anticorrelation between neutral hydrogen column density and impact parameter (between the galaxy and line of sight) will likely be observed for a variety of scenarios, whether or not the identified galaxies actually give rise to the absorption. While some stronger Ly\alpha absorbers must be associated with particular galaxies, such an anticorrelation can occur largely as a result of galaxy selection effects. Therefore other tests, such as those in which the absorption cross sections of galaxies are examined for a wide range of galaxy properties, will be needed to establish the relationship between galaxies and Ly\alpha absorbers.


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