New Population Synthesis Models of the Cosmic UV Background
Abstract
We present improved synthesis models of the evolving spectrum of the UV/X-ray diffuse background, updating and extending our previous results. A "minimal cosmic reionization model" is presented in which the galaxy UV emissivity traces recent determinations of the cosmic history of star formation, the luminosity-weighted escape fraction of hydrogen-ionizing radiation increases rapidly with redshift, from 1% at z=3 to 50% at z=8.5, the clumping factor of the intergalactic medium is C=3, and Population III stars make a negligible contribution to the metagalactic flux. The model provides a good fit to the hydrogen-ionization rates inferred from flux decrement measurements, and yields an optical depth to Thomson scattering, tau_e=0.085, that is in agreement with WMAP results.
Keywords
Cite
@article{arxiv.1103.5226,
title = {New Population Synthesis Models of the Cosmic UV Background},
author = {Francesco Haardt and Piero Madau},
journal= {arXiv preprint arXiv:1103.5226},
year = {2011}
}
Comments
7 pages, 3 figures, proc. of 25th Texas Symposium on Relativistic Astrophysics - TEXAS 2010, December 06-10, 2010, Heidelberg, Germany