1999/06/28 by Greg L. Bryan, Marie E. Machacek, M. Macháček · 9 citations
Chemistry · Mathematics · Physics and Astronomy · #Amplitude #Astrophysics #Astrophysics and Star Formation Studies #Computational physics #Cutoff #Distribution (mathematics) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Intergalactic medium #Limit (mathematics) #Line-of-sight #Lyman limit #Lyman-alpha forest #Mathematical analysis #Mathematics #Optics #Physics #Quantum mechanics #Quasar #Redshift #Spectral density #Spectroscopy and Laser Applications #Statistics #astro-ph
paper · pdf · doi:10.1086/308735
17 pages, 11 figures, submitted to ApJ
arxiv created 1999/06/28 · openalex publication_date 2000/05/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We investigate a method to determine the temperature-density relation of the intergalactic medium (IGM) at z~2-4 using quasar absorption line systems. Using a simple model combined with numerical simulations we show that there is a lower cutoff in the distribution of column density (NHI) and line width (b parameter). The location of this cutoff can be used to determine the temperature-density relation (under certain conditions). We describe and test an algorithm to do this. The method works as long as the amplitude of fluctuations on these scales (~100 kpc) is sufficiently large. Models with less power can mimic higher temperatures. A preliminary application is made to data from two quasar lines-of-sight, and we determine an upper limit to the temperature of the IGM. Finally, we examine the full distribution of b-parameters and show that this is completely specified by just two parameters: the temperature of the gas and the amplitude of the power spectrum. Using the temperature upper limit measured with the NHI-b cutoff method, we derive an upper limit to the amplitude of the power spectrum.