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  • Frequency and Abundance of Binary Supermassive Black Holes from Optical Variability Surveys (Fabulovs): Hubble Space Telescope Imaging of Radial-velocity-selected Binary Candidates

This content will become publicly available on August 8, 2026

Title: Frequency and Abundance of Binary Supermassive Black Holes from Optical Variability Surveys (Fabulovs): Hubble Space Telescope Imaging of Radial-velocity-selected Binary Candidates
Abstract Subparsec binary supermassive black holes (BSBHs) should be common from galaxy mergers, yet direct evidence has been elusive. We present Hubble Space Telescope (HST)/WFC3IR F160W imaging for a sample of eight candidate subparsec BSBHs at redshiftsz ∼ 0.1–0.5, as well as cross-comparison with a sample of ordinary quasars with archival HST/WFC3 IR F160W images. These eight candidate subparsec BSBHs were identified from multiepoch spectroscopic surveys of quasars (including both typical quasars and those with single-peaked velocity-offset broad lines), whose broad Hβlines are significantly offset (by ≳ a few hundred kilometers per second) from the systemic redshifts. We directly test the prediction that the host galaxies of BSBHs would have a higher fraction of disturbed morphologies and younger stellar bulges from recent interactions than those of control quasars. After careful subtraction of the central quasar light, our candidate BSBH hosts show a statistically undifferentiated distribution of host asymmetry, indicative of a similar fraction of recent mergers. While a significantly larger sample is needed to place this result on a much firmer statistical ground, it opens questions as to the timescale differences between galaxy merger and BSBH formation, or the efficacy of the radial-velocity-shift-based selection of subparsec BSBH candidates.  more » « less
Award ID(s):
2206499
PAR ID:
10633819
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
AAS Jounals
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
989
Issue:
1
ISSN:
0004-637X
Page Range / eLocation ID:
119
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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