NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-06-27 T03:22:31 PDT
Help | Comment | NED Home

For refcode 2002ApJ...571..654D:
Retrieve 165 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by American Astronomical Society. Reproduced by permission
2002ApJ...571..654D A Uniform Analysis of the Ly{alpha} Forest at z = 0-5. IV. The Clustering and Evolution of Clouds at z <= 1.7 Adam Dobrzycki Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 70, Cambridge, MA 02138; adobrzycki@cfa.harvard.edu and Jill Bechtold, Jennifer Scott, and Miwa Morita Steward Observatory, University of Arizona, Tucson, AZ 85721; jbechtold@as.arizona.edu, jscott@as.arizona.edu, mmorita@as.arizona.edu Received 2001 July 25; accepted 2002 February 1 ABSTRACT We present results on the evolution and clustering of Ly{alpha} lines at low redshift as part of our series "A Uniform Analysis of the Ly{alpha} Forest at z = 0-5." The sample analyzed in this paper contains 1298 Ly{alpha} absorption lines from 165 quasar spectra mined from the archives of the Faint Object Spectrograph on the Hubble Space Telescope (HST). Our sample extends to z ~ 1.7, slightly higher than the sample analyzed by the HST Quasar Absorption Line Key Project. We confirm the result from the Key Project that the number density evolution of Ly{alpha} lines at low redshifts can be described by a power law that is significantly flatter than that found at high z. We find that the evolution is somewhat steeper than obtained previously. Specifically, we find {gamma} = 0.54 +/- 0.21 for lines with equivalent widths greater than 0.24 A and {gamma} = 0.60 +/- 0.14 using a variable equivalent width threshold. We find that the difference between our and Key Project results is likely attributable to different redshift coverage of the two samples. The results concerning the number density evolution are not significantly affected if one includes Ly{alpha} lines which are members of metal systems. Object-to-object fluctuations in the number of lines detected are small, indicating a high degree of uniformity in the intergalactic medium on large scales. We find marginal evidence that weak and strong lines undergo different evolution. We find weak clustering for Ly{alpha} lines at velocity separations {DELTA}V <= 500 km s^-1^, weaker than the level predicted from an earlier analysis by Ulmer of a small subsample of the Key Project data. We see no correlations for metal system-Ly{alpha} forest or extensive metal system-Ly{alpha} forest combinations. Subject headings: intergalactic medium - quasars: absorption lines
Retrieve 165 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home