The evolution of a pre-heated Intergalactic Medium - AstrophysicsReport as inadecuate

The evolution of a pre-heated Intergalactic Medium - Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We analyse the evolution of the Intergalactic Medium IGM by means of anextended set of large box size hydrodynamical simulations which includepre-heating. We focus on the properties of the z~2 Lyman-alpha forest and onthe population of clusters and groups of galaxies at z=0. We investigate thedistribution of voids in the Lyman-alpha flux and the entropy-temperaturerelation of galaxy groups, comparing the simulation results to recent data fromhigh-resolution quasar spectra and from X-ray observations. Pre-heating isincluded through a simple phenomenological prescription, in which at z=4 theentropy of all gas particles, whose overdensity exceeds a threshold valuedelta h is increased to a minimum value K fl. While the entropy level observedin the central regions of galaxy groups requires a fairly strong pre-heating,with K fl>100 keV cm^2, the void statistics of the Lyman-alpha forest imposethat this pre-heating should take place only in relatively high-densityregions, in order not to destroy the cold filaments that give rise to theforest. We conclude that any injection of non-gravitational energy in thediffuse baryons should avoid low-density regions at high redshift and-or takeplace at relatively low redshift.

Author: S. Borgani, M. Viel


Related documents