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arXiv · 2609.39977

A New Sample of Closely Separated Dual and Binary AGN Candidates Revealed with the Radio Fundamental Catalog

Emma Schwartzman·Ryan Pfeifle·Tracy Clarke·Nathan Secrest·Henrique Schmitt·Barry Rothberg
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Abstract

The Big Multi-AGN Catalog (BigMAC) provides the first literature-complete compilation of confirmed and candidate dual, binary, and recoiling active galactic nuclei (AGN). The BigMAC provides a basis for the first population-wide radio study of multiple AGN (multi-AGN). The Radio Fundamental Catalog (RFC) is composed of four decades of Very Long Baseline Interferometry (VLBI) observations capable of resolving parsec-scale structure. All BigMAC candidate and confirmed multi-AGN were cross-matched to the RFC, highlighting a total of 241 BigMAC sources with available RFC imaging. We present the first detailed analysis of the ten systems exhibiting multiple compact components, most likely to be radio multi-AGN. Using multi-frequency radio and supporting multiwavelength information, we assess whether each system is more consistent with dual/binary AGN or intrinsic jet structure. The dual/binary nature of six systems is further supported by our radio analysis, while the four remaining systems are more plausibly explained by compact jet activity. Several candidate multi-AGN systems exhibit projected separations of only a few to tens of parsecs. In many cases, the parsec-scale radio separations are orders of magnitude smaller than the separations inferred from the observations that originally motivated their selection, emphasizing the importance of VLBI follow-up. Because all ten sources are members of the International Celestial Reference Frame (ICRF) and display significant intrinsic radio structure, they also represent potential sources of astrometric error. This work establishes the RFC as an archival resource for characterizing the closest SMBH pairs while improving future ICRF realizations.

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Emma Schwartzman, Ryan Pfeifle, Tracy Clarke, Nathan Secrest, Henrique Schmitt, Barry Rothberg. 2026-09-30. A New Sample of Closely Separated Dual and Binary AGN Candidates Revealed with the Radio Fundamental Catalog. https://arxiv.org/abs/2609.39977

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