Physical Sciences and Mathematics Commons^™

The Low-Redshift Ly Alpha Forest In Cold Dark Matter Cosmologies, R Dave, L Hernquist, N Katz, Dh Weinberg

Astronomy Department Faculty Publication Series

We study the physical origin of the low-redshift Lyα forest in hydrodynamic simulations of four cosmological models, all variants of the cold dark matter scenario. Our most important conclusions are insensitive to the cosmological model, but they depend on our assumption that the UV background declines at low redshift in concert with the declining population of quasar sources. We find that the expansion of the universe drives rapid evolution of dN/dz (the number of absorbers per unit redshift above a specified equivalent width threshold) at z1.7, but that at lower redshift the fading of the UV background …