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arXiv · 2311.08449

X-ray Redshifts for Obscured Active Galactic Nuclei with AXIS Deep and Intermediate Surveys

Alessandro Peca·Nico Cappelluti·Stefano Marchesi·Edmund Hodges-Kluck·Adi Foord
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Abstract

This study presents the capabilities of the AXIS telescope in estimating redshifts from X-ray spectra alone (X-ray redshifts, XZs). Through extensive simulations, we establish that AXIS observations enable reliable XZ estimates for more than 5500 obscured Active Galactic Nuclei (AGN) up to redshift $z\sim 6$ in the proposed deep (7 Ms) and intermediate (375 ks) surveys. Notably, at least 1600 of them are expected to be in the Compton-Thick regime ($\log N_H/\mathrm{cm^{-2}}\geq 24$), underscoring the pivotal role of AXIS in sample these elusive objects that continue to be poorly understood. XZs provide an efficient alternative for optical/infrared faint sources, overcoming the need for time-consuming spectroscopy, potential limitations of photometric redshifts, and potential issues related to multi-band counterpart association. This approach will significantly enhance the accuracy of constraints on the X-ray luminosity function and obscured AGN fractions up to high redshift. This White Paper is part of a series commissioned for the AXIS Probe Concept Mission; additional AXIS White Papers can be found at the AXIS website (http://axis.astro.umd.edu) with a mission overview here: arXiv:2311.00780.

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Alessandro Peca, Nico Cappelluti, Stefano Marchesi, Edmund Hodges-Kluck, Adi Foord. 2023-11-14. X-ray Redshifts for Obscured Active Galactic Nuclei with AXIS Deep and Intermediate Surveys. https://doi.org/10.3390/universe10060245

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