Evolution of the Ionizing Photon Luminosity Function
Abstract
Counting the number and brightness of ionizing radiation sources out to a redshift of z ~ 1.2 will revolutionize our understanding of how the ionizing background is created and sustained by the embedded growth of meta-galactic structures. The sheer number of sparsely separated targets required to efficiently construct redshift binned luminosity functions is industrial in scale, driving the need for low spectral resolution multi-object spectroscopy (MOS) with a short wavelength cut-off ~ 1000 {\AA}, a sensitivity in the far-UV to better than 30 abmag, and an instantaneous field-of-view ~ (2'). A MOS on Habitable Worlds Observatory is the only instrument that could conceivably carry out such an ambitious observing program. This program will quantify how much of the ionizing radiation produced by galaxies is attenuated by intervening neutral H, He and dust, and how much escapes to maintain the universe in a mostly ionized state.
Cite
@article{arxiv.2507.02178,
title = {Evolution of the Ionizing Photon Luminosity Function},
author = {Stephan R. McCandliss and Swara Ravindranath and Sangeeta Malhotra and Chris Packham and Sophia Flury and Alexandra Le Reste and Allison Strom and Marc Postman and John OMeara},
journal= {arXiv preprint arXiv:2507.02178},
year = {2025}
}
Comments
Science Case Development Document for the Habitable Worlds Observatory - 9 pages 6 figures - submitted to ASP conference proceedings 15 September 2025