THE LOW-REDSHIFT EVOLUTION OF THE LYMAN-ALPHA FOREST

Citation
T. Theuns et al., THE LOW-REDSHIFT EVOLUTION OF THE LYMAN-ALPHA FOREST, Monthly Notices of the Royal Astronomical Society, 297(2), 1998, pp. 49-52
Citations number
31
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Astronomy & Astrophysics
ISSN journal
0035-8711
Volume
297
Issue
2
Year of publication
1998
Pages
49 - 52
Database
ISI
SICI code
0035-8711(1998)297:2<49:TLEOTL>2.0.ZU;2-L
Abstract
The low-redshift evolution of the intergalactic medium is investigated using hydrodynamic cosmological simulations. The assumed cosmological model is a critical density cold dark matter universe. The imposed un iform background of ionizing radiation has the amplitude, shape and re dshift evolution as computed from the observed quasar luminosity funct ion by Haardt & Madau. We have analysed simulated Lyman-alpha spectra using Voigt-profile fitting, mimicking the procedure with which quasar spectra are analysed. Our simulations reproduce the observed evolutio n of the number of Lyman-alpha absorption lines over the whole observe d interval of z = 0.5 to 4. In particular, our simulations show that t he decrease in the rate of evolution of Lyman-alpha absorption lines a t z less than or equal to 2, as observed by the Hubble Space Telescope , can be explained by the steep decline in the photoionizing backgroun d resulting from the rapid decline in quasar numbers at low redshift.