Broadband Intensity Tomography: Spectral Tagging of the Cosmic UV Background

Understand

Cosmic photons can be efficiently collected by broadband intensity mapping but information on their emission redshift and frequency is largely lost.

• We introduce a technique to statistically recover these otherwise collapsed dimensions by exploiting information in spatial fluctuations and apply it to the Galaxy Evolution Explorer (GALEX) All Sky and Medium Imaging Surveys.
• By spatially cross-correlating photons in the GALEX far-UV (1500A) and near-UV (2300A) bands with a million spectroscopic objects in the Sloan Digital Sky Survey as a function of redshift, we robustly detect the redshift-dependent intensity of the UV background (UVB) modulated by its clustering bias up to $z\sim2$.
• These measurements clearly reveal the imprints of UVB spectral features redshifting through the filters.