Overmassive supermassive black holes in SDSS close galaxy pairs

[2608.27730] Overmassive supermassive black holes in SDSS close galaxy pairs Skip to main content Search Submit Donate Log in Astrophysics > Astrophysics of Galaxies arXiv:2608.27730 (astro-ph) [Submitted on 27 Aug 2026] Title: Overmassive supermassive black holes in SDSS close galaxy pairs Authors: Maggie C. Huber , Julia M. Comerford , Joseph Simon View PDF HTML (experimental) Abstract: Supermassive black holes (SMBHs) and their host-galaxies coevolve through channels such as hierarchical merging and AGN feedback, establishing tight scaling relations between SMBH masses and properties of the host-galaxy. These scaling relations, particularly those with host-galaxy bulge mass (M${_\text{b}}$) and stellar velocity dispersion ($\sigma$), are widely used to estimate SMBH masses. Galaxy mergers drive gas into the centers of galaxies, enhancing SMBH growth and stellar bulge growth but not necessarily in tandem, so it is necessary to determine if galaxies undergoing a merger still follow SMBH-host-galaxy scaling relations. In this study, we explore scaling relations in galaxy mergers by taking advantage of the well-established value-added catalogs in the Sloan Digital Sky Survey. These catalogs provide close galaxy pairs, AGN broad lines for SMBH mass measurements, and bulge-disk decomposed stellar masses. We compare SMBH mass estimates from M$_\bullet-$M${_\text{b}}$ to SMBH mass estimates from AGN broad lines and find that SMBH mass growth outpaces the bulge for AGN residing in the secondary (less massive) bulge and for smaller physical separations between galaxies in a pair. Using our full sample of close galaxy pairs, we find that M$_\bullet-$M${_\text{b}}$ and M$_\bullet- \sigma$ predict significantly different fractions of major and minor black hole mergers with M$_\bullet-$M${_\text{b}}$ predicting black hole mass ratios closer to 1:1 and $6-20\%$ more major mergers overall. These results have major implications, including for predictions of astrophysical gravitational-waves and high-redshift overmassive SMBHs. Comments: ApJ Accepted version. 28 pages, 8 figures, 5 tables. Tables 1 and 2 are available as machine-readable tables in the published version Subjects: Astrophysics of Galaxies (astro-ph.GA) Cite as: arXiv:2608.27730 [astro-ph.GA] (or arXiv:2608.27730v1 [astro-ph.GA] for this version) https://doi.org/10.48550/arXiv.2608.27730 Focus to learn more arXiv-issued DOI via DataCite Related DOI : https://doi.org/10.3847/1538-4357/ae975b Focus to learn more DOI(s) linking to related resources Submission history From: Maggie Huber [ view email ] [v1] Thu, 27 Aug 2026 21:40:40 UTC (618 KB) Full-text links: Access Paper: View PDF HTML (experimental) TeX Source view license Current browse context: astro-ph.GA < prev | next > new | recent | 2026-08 Change to browse by: astro-ph References & Citations SciX Google Scholar Semantic Scholar export BibTeX citation Bookmark Bibliographic Tools Bibliographic and Citation Tools Bibliographic Explorer Toggle Bibliographic Explorer ( What is the Explorer? ) Connected Papers Toggle Connected Papers ( What is Connected Papers? ) Litmaps Toggle Litmaps ( What is Litmaps? ) scite.ai Toggle scite Smart Citations ( What are Smart Citations? ) Code, Data, Media Code, Data and Media Associated with this Article alphaXiv Toggle alphaXiv ( What is alphaXiv? ) Links to Code Toggle CatalyzeX Code Finder for Papers ( What is CatalyzeX? ) DagsHub Toggle DagsHub ( What is DagsHub? ) GotitPub Toggle Gotit.pub ( What is GotitPub? ) Huggingface Toggle Hugging Face ( What is Huggingface? ) ScienceCast Toggle ScienceCast ( What is ScienceCast? ) Demos Demos Replicate Toggle Replicate ( What is Replicate? ) Spaces Toggle Hugging Face Spaces ( What is Spaces? ) Spaces Toggle TXYZ.AI ( What is TXYZ.AI? ) Related Papers Recommenders and Search Tools Link to Influence Flower Influence Flower ( What are Influence Flowers? ) Core recommender toggle CORE Recommender ( What is CORE? ) IArxiv recommender toggle IArxiv Recommender ( What is IArxiv? ) Author Venue Institution Topic About arXivLabs arXivLabs: experimental projects with community collaborators arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website. Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them. Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs . Which authors of this paper are endorsers? | Disable MathJax ( What is MathJax? ) We gratefully acknowledge support from our major funders , member institutions , and all contributors. About · Help · Contact · Subscribe · Copyright · Privacy · Accessibility · Operational Status (opens in new tab)

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