1999/06/30 by Massimo Ricotti, Nickolay Y. Gnedin, J. Michael Shull
Physics and Astronomy · #Astrophysics #Astrophysics and Star Formation Studies #Equation of state #Galaxies: Formation, Evolution, Phenomena #Galaxy #Intergalactic medium #Intergalactic travel #Isothermal process #Lyman-alpha forest #Physics #Quantum mechanics #Redshift #Reionization #Stellar, planetary, and galactic studies #Thermodynamics #astro-ph
paper · pdf · doi:10.1086/308733
published as Astrophys.J.534:41-56,2000 · Revised version accepted for publication in ApJ. Vol. 534 May 1, 2000 (in press); 32 pages, 13 figures, 7 tables
arxiv created 1999/12/11 · openalex publication_date 2000/05/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We develop a method to extract the "effective equation of state" of the intergalactic medium from the Doppler ( b ) parameter distribution of the low-density Lyα forest. We test the method on numerical simulations and then apply it to published observations of the Lyα forest at redshifts z ≃ 0-4. We find that the effective equation of state is close to isothermal at redshift z ~ 3, indicating that a second reheating of the intergalactic medium took place at z ~ 3. This reheating can plausibly be identified with the reionization of He II observed to occur at z ~ 3.