A High Resolution Search for Dual AGN Candidates in Mergers: A Pre-Selection Strategy using Keck AO

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Bibliographic Details
Main Authors:	Vazquez, Camilo, Satyapal, S., Canalizo, G., Secrest, N. J., Pfeifle, R. W., Bohn, T., Nyland, K., Aravindan, A., Blecha, L., Cann, J. M., Doan, S., Hicks, E. K., Kurczynski, P., Juneau, S., Malkan, M., McDonald, M., McKaig, J., Nair, P., Rothberg, B., Muller-Sanchez, F., Schwartzman, E., Sexton, R., U, V.
Format:	Preprint
Published:	2025
Subjects:	Astrophysics of Galaxies
Online Access:	Acceder al recurso
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author	Vazquez, Camilo Satyapal, S. Canalizo, G. Secrest, N. J. Pfeifle, R. W. Bohn, T. Nyland, K. Aravindan, A. Blecha, L. Cann, J. M. Doan, S. Hicks, E. K. Kurczynski, P. Juneau, S. Malkan, M. McDonald, M. McKaig, J. Nair, P. Rothberg, B. Muller-Sanchez, F. Schwartzman, E. Sexton, R. U, V.
author_facet	Vazquez, Camilo Satyapal, S. Canalizo, G. Secrest, N. J. Pfeifle, R. W. Bohn, T. Nyland, K. Aravindan, A. Blecha, L. Cann, J. M. Doan, S. Hicks, E. K. Kurczynski, P. Juneau, S. Malkan, M. McDonald, M. McKaig, J. Nair, P. Rothberg, B. Muller-Sanchez, F. Schwartzman, E. Sexton, R. U, V.
contents	Accreting supermassive black holes (SMBHs) in galaxy mergers with separations $<$ 1 kpc are crucial to our understanding of SMBH growth, galaxy evolution, and SMBH binary evolution. Despite their importance, few are known, and most have been discovered serendipitously. In this work, we develop and test a method to systematically pre-select candidate advanced mergers likely to contain unresolved sub-kpc nuclear substructure constituting high-priority dual-AGN candidates for follow-up spectroscopy. By exploiting the survey area and astrometric precision of the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey (SDSS), we identified 46 nearby advanced mergers that have red WISE colors ($W_1-W_2>0.5$) indicative of accretion activity and significant sub-arcsecond offsets between their optical and infrared coordinates as measured by SDSS and WISE. We conducted high-resolution adaptive optics (AO) observations with the Keck NIRC2 camera in the $K_p$ band ($2.124 μm$, $Δλ= 0.351 μm$) to search for unresolved substructure suggested by the optical-to-infrared offsets. We find that 20/46 (43\%) of the sample shows substructure tracing the SDSS/WISE offset and unresolved by SDSS , representing a higher yield than previous pre-selection techniques such as double-peaked [O III] or hard X-ray selection. These results demonstrate that the SDSS/WISE offset method provides an efficient pathway for identifying late-stage mergers and dual-AGN candidates for spectroscopic confirmation. Archival optical Hubble Space Telescope (HST) imaging reveals that substructure identified with Keck is often missed in the optical or erroneously identified due to partial obscuration, underscoring the importance of infrared studies of late-stage mergers.
format	Preprint
id	arxiv_https___arxiv_org_abs_2507_05250
institution	arXiv
publishDate	2025
record_format	arxiv
spellingShingle	A High Resolution Search for Dual AGN Candidates in Mergers: A Pre-Selection Strategy using Keck AO Vazquez, Camilo Satyapal, S. Canalizo, G. Secrest, N. J. Pfeifle, R. W. Bohn, T. Nyland, K. Aravindan, A. Blecha, L. Cann, J. M. Doan, S. Hicks, E. K. Kurczynski, P. Juneau, S. Malkan, M. McDonald, M. McKaig, J. Nair, P. Rothberg, B. Muller-Sanchez, F. Schwartzman, E. Sexton, R. U, V. Astrophysics of Galaxies Accreting supermassive black holes (SMBHs) in galaxy mergers with separations $<$ 1 kpc are crucial to our understanding of SMBH growth, galaxy evolution, and SMBH binary evolution. Despite their importance, few are known, and most have been discovered serendipitously. In this work, we develop and test a method to systematically pre-select candidate advanced mergers likely to contain unresolved sub-kpc nuclear substructure constituting high-priority dual-AGN candidates for follow-up spectroscopy. By exploiting the survey area and astrometric precision of the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital Sky Survey (SDSS), we identified 46 nearby advanced mergers that have red WISE colors ($W_1-W_2>0.5$) indicative of accretion activity and significant sub-arcsecond offsets between their optical and infrared coordinates as measured by SDSS and WISE. We conducted high-resolution adaptive optics (AO) observations with the Keck NIRC2 camera in the $K_p$ band ($2.124 μm$, $Δλ= 0.351 μm$) to search for unresolved substructure suggested by the optical-to-infrared offsets. We find that 20/46 (43\%) of the sample shows substructure tracing the SDSS/WISE offset and unresolved by SDSS , representing a higher yield than previous pre-selection techniques such as double-peaked [O III] or hard X-ray selection. These results demonstrate that the SDSS/WISE offset method provides an efficient pathway for identifying late-stage mergers and dual-AGN candidates for spectroscopic confirmation. Archival optical Hubble Space Telescope (HST) imaging reveals that substructure identified with Keck is often missed in the optical or erroneously identified due to partial obscuration, underscoring the importance of infrared studies of late-stage mergers.
title	A High Resolution Search for Dual AGN Candidates in Mergers: A Pre-Selection Strategy using Keck AO
topic	Astrophysics of Galaxies
url	https://arxiv.org/abs/2507.05250