X-ray Redshift for obscured AGN with AXIS deep and intermediate surveys

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2311.08449.pdf (687.89 KB)

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https://arxiv.org/abs/2311.08449

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https://doi.org/10.48550/arXiv.2311.08449
 http://hdl.handle.net/11603/31009

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UMBC Physics Department
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https://orcid.org/0000-0002-1616-1701

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2023-11-14

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journal articles
preprints
white papers
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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 ∼ 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 Nₕ/cm⁻² ≥ 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.