Cosmic Pairs: A DESI Census of Dual and Offset AGN as Precursors to Massive Black Hole Binaries

arXiv:2607.27390 · astro-ph.GA, astro-ph.HE · Submitted 2026-07-29 · Read on arXiv

Ekaterine Dadiani, Antonella Palmese, Yihao Zhou, Nianyi Chen, Tiziana Di Matteo, Alejandro Eróstegui, Mar Mezcua, Jessica Nicole Aguilar, Steven Ahlen, Stephen Bailey, Florian Beutler, Davide Bianchi, David Brooks, Todd Claybaugh, Axel de la Macorra, Arjun Dey, Biprateep Dey, Peter Doel, Victoria A. Fawcett, Benjamin Floyd, Andreu Font-Ribera, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Mustapha Ishak, Robert Kehoe, Anthony Kremin, Ofer Lahav, Andrew Lambert, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, Ramon Miquel, John Moustakas, Seshadri Nadathur, Enrique Paillas, Will J. Percival, Francisco Prada, Ignasi Pérez-Ràfols, Ragadeepika Pucha, Corentin Ravoux, Graziano Rossi, Rossana Ruggeri, Eusebio Sanchez, Christoph Saulder, David Schlegel, Michael Schubnell, Hee-Jong Seo, Joseph Harry Silber, Małgorzata Siudek, Gregory Tarlé, Benjamin Alan Weaver, DESI Collaboration

astro-ph.GA, astro-ph.HE

Submitted: 2026-07-29

Comments: 38 pages, 18 figures, 1 table. To be submitted to ApJ

Code: https://github.com/desihub/redrock

License: http://creativecommons.org/licenses/by/4.0/

The gist: We present a systematic census of dual and offset active galactic nuclei (AGN) using spectroscopic data from the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI).

Terminology

Abstract

We present a systematic census of dual and offset active galactic nuclei (AGN) using spectroscopic data from the first data release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). After correcting for observational systematics, our final sample contains >7,000 dual AGN and 27,000 galaxy pairs containing one AGN over the redshift range 0 z 3.6. This sample expands the known dual AGN sample by about 1-2 orders of magnitude at 0.2 z 0.4, includes about 50 dwarf dual AGN candidates in a regime where only a handful were previously known, and triples the census at z>2. Dual AGN are preferentially found at small separations, consistent with merger-driven triggering of AGN activity. The two members of a pair differ in their star formation response: the more massive (primary) host changes little with separation, while the less massive (secondary) lies about 0.3 dex above matched inactive and one-AGN companions at the same projected separation in main-sequence offset. Using ASTRID simulations, we predict that the fraction of DESI dual AGN whose central black holes will merge by z about 0 increases with redshift, reaching about 76% by z about 2, while the fraction producing LISA-detectable mergers peaks at about 37% near z about 0.9. These results provide the largest uniformly selected spectroscopic sample of kpc-scale dual and offset AGN candidates from a single survey, connecting their host-galaxy and AGN demographics to the progenitor population of massive black hole mergers detectable by LISA.

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