Speaker
Description
I will present results from the Extragalactic Serendipitous Swift Survey (ExSeSS) along with initial results from an SDSS-V open-fibre program that is providing spectroscopic follow-up of a bright, hard X-ray selected sub-sample. The ExSeSS sample has enabled us to measure the differential number counts of X-ray sources as a function of 2-10~keV flux, providing insight into the population of Active Galactic Nuclei (AGN) in an unexplored regime. We find discrepancies between the ExSeSS measurements and AGN population synthesis models, indicating a change in the properties of the AGN population over this flux range that is not fully described by current models.
Based on the brightest sources from the ExSeSS sample, combined with additional 4.5-12keV selected sources from 4XMM, we created a new sample of ~10,000 hard X-ray selected sources for follow-up by SDSS-V as part of the open-fibre program. Our initial analysis has yielded spectroscopy for 975 of these sources to date and is still growing.
Our ongoing work focuses on the classification of the sources and their redshifts, with the aim of creating a comprehensive understanding of the individual spectra of each source, as well as constructing composite spectra for AGN in this sample. We aim to compare this sample to the eROSITA sources and examine differences due to a harder selection. We anticipate that our findings will contribute significantly to our understanding of obscured AGN populations and have implications for future research in this field.
