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A Census of WISE-Selected Dual and Offset Active Galactic Nuclei

Presentation #406.06 in the session Blazars, Quasars, and AGN.

Published onJul 01, 2023
A Census of WISE-Selected Dual and Offset Active Galactic Nuclei

A significant fraction of the active galactic nuclei (AGN) population, and hence of supermassive black hole (SMBH) growth, is obscured by large columns of gas and dust. For more than a decade, data from NASA’s Wide-field Infrared Survey Explorer (WISE) has propelled our knowledge of this obscured AGN population. To further enhance the utility of WISE, we have constructed a catalog of photometric redshifts and AGN/host galaxy physical properties for 695,273 galaxies hosting WISE-selected AGN based on broadband spectral energy distribution models (Barrows et al. 2021, ApJ, 922, 179). The wide-area nature of this catalog vastly increases the number of WISE AGN with redshift estimates, including the number of known obscured AGN out to redshifts of z~3. The catalog is primed for a wide range of studies focused on AGN (obscured or otherwise) and their host galaxies. Here we provide an overview of this data product and recent results from applying it to the identification of obscured AGN in probabilistic galaxy pairs across the sky. While interacting pairs of obscured AGN had previously been rarities, use of this wide-area photometric catalog has resulted in the largest selection of obscured dual AGN to date. We use it to provide the first direct evidence of how the AGN pair fraction increases significantly with AGN obscuration level for galaxy pairs with one or two AGN. Higher AGN merger fractions are also found among galaxies with large specific star formation rates, suggesting merger-driven SMBH-galaxy co-evolution. Increased AGN obscuration is also associated with increased host galaxy global star formation, suggesting that an appreciable amount of the dust obscuring AGN in mergers may be distributed on large spatial scales. Moreover, we show how an excess of AGN are found in late-stage mergers (under 20 kpc pair separations). This excess is significantly greater than that of optically-selected AGN, and it peaks for obscured AGN in dual systems due to correlated triggering.

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