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The Lyman alpha forest in the spectra of quasistellar objects

Rauch­, Michael (1998) The Lyman alpha forest in the spectra of quasistellar objects. Annual Review of Astronomy and Astrophysics, 36 . pp. 267-316. ISSN 0066-4146. http://resolver.caltech.edu/CaltechAUTHORS:RAUaraa98

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Abstract

Observations of redshifted Lyman alpha (Ly alpha) forest absorption in the spectra of quasistellar objects (QSOs) provide a highly sensitive probe of the distribution of gaseous matter in the universe. Over the past two decades, optical spectroscopy with large ground-based telescopes, and more recently ultraviolet (UV) spectroscopy from space, have yielded a wealth of information on what appears to be a gaseous, photoionized intergalactic medium (IGM), partly enriched by the products of stellar nucleosynthesis, residing in coherent structures over many hundreds of kiloparsecs. Recent progress with cosmological hydro-simulations based or hierarchical structure formation models has led to important insights into the physical structures giving rise to the forest. If these ideas are correct, a truly inter- and protogalactic medium [at high redshift (z similar to 3), the main repository of baryons] collapses under the influence of dark matter gravity into flattened or filamentary structures, which are seen in absorption against background QSOs. With decreasing redshift, galaxies forming in the denser regions may contribute an increasing part of the Ly alpha absorption cross section. Comparisons between large data samples from the new generation of telescopes and artificial Ly alpha forest spectra from cosmological simulations promise to become a useful cosmological tool.


Item Type:Article
Additional Information:"Reprinted, with permission, from the Annual Review of Astronomy and Astrophysics, Volume 36 copyright 1998 by Annual Reviews, www.annualreviews.org" I am grateful to Bob Carswell, Martin Haehnelt, Jordi Miralda-Escude, and Wal Sargent for reading earlier drafts and to NASA for support through grant HF-01075.01-94A from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.
Subject Keywords:QUASISTELLAR OBJECT (QSO) ABSORPTION LINES; INTERGALACTIC MEDIUM (IGM); GALAXY FORMATION; COSMOLOGY; ULTRAVIOLET BACKGROUND RADIATION; HIGH-REDSHIFT QUASARS; PHOTOIONIZED INTERGALACTIC MEDIUM; HIGH-RESOLUTION SPECTROSCOPY; COLUMN DENSITY DISTRIBUTION; LARGE-SCALE DISTRIBUTION; ABSORPTION-LINE SYSTEMS; HUBBLE-SPACE-TELESCOPE; DARK-MATTER COSMOGONY; HE-I ABSORPTION; HELIUM ABSORPTION
Record Number:CaltechAUTHORS:RAUaraa98
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:RAUaraa98
Alternative URL:http://dx.doi.org/10.1146/annurev.astro.36.1.267
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1486
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:23 Jan 2006
Last Modified:26 Dec 2012 08:44

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