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The Local Ly-alpha Forest: HI in Nearby Intergalactic Space

John T. Stocke·J. Michael Shull·Steven V. Penton·Brad K. Gibson·Mark L. Giroux·Kevin M. McLin
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Abstract

Detecting HI using redshifted Ly-alpha absorption lines is 1e6 times more sensitive than using the 21cm emission line. We review recent discoveries of HI Ly-alpha absorbers made with the Hubble Space Telescope (HST) which have allowed us a first glimpse at gas in local intergalactic space between us and the ``Great Wall''. Despite its mere 2.4m aperture, HST can detect absorbers with column densities as low as those found using Keck at high-z (log N(HI)=12.5 1/cm**2). New results that will be discussed include: the evolution of absorbers with redshift, the location of absorbers relative to galaxies (including the two-point correlation function for absorbers), the metallicity of absorbers far from galaxies, and the discovery of hot 1e5-1e6 K (shock-heated?) absorbers. The unique ability of VLA HI observations in discovering the nearest galaxies to these absorbers is stressed.

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John T. Stocke, J. Michael Shull, Steven V. Penton, Brad K. Gibson, Mark L. Giroux, Kevin M. McLin. 2000-09-13. The Local Ly-alpha Forest: HI in Nearby Intergalactic Space. https://arxiv.org/abs/astro-ph/0009190

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