Identifying High-Redshift Active Galactic Nuclei Using X-Ray Hardness
Identifying High-Redshift Active Galactic Nuclei Using X-Ray Hardness
The X-ray color (hardness ratio) of optically undetected X-ray sources can be used to distinguish obscured active galactic nuclei (AGNs) at low and intermediate redshift from viable high-redshift (i.e., z > 5) AGN candidates. This will help determine the space density, ionizing photon production, and X-ray background contribution of the …