Investigating the Bulge Morphology of Dual AGN Host Galaxies from the GOTHIC survey

Abstract

We present a structural analysis of bulges in dual active galactic nuclei (AGN) host galaxies. Dual AGN arise in galaxy mergers where both supermassive black holes (SMBHs) are actively accreting. The AGN are typically embedded in compact bulges, which appear as luminous nuclei in optical images. Galaxy mergers can result in bulge growth, often via star formation. The bulges can be disky (pseudobulges), classical bulges, or belong to elliptical galaxies. Using SDSS DR18 gri images and GALFIT modelling, we performed 2D decomposition for 131 dual AGN bulges (comprising 61 galaxy pairs and 3 galaxy triplets) identified in the GOTHIC survey. We derived sérsic indices, luminosities, masses, and scalelengths of the bulges. Most bulges (105/131) are classical, with sérsic indices lying between $n=2$ and $n=8$. Among these, 64% are elliptical galaxies, while the remainder are classical bulges in disc galaxies. Only $\sim$20% of the sample exhibit pseudobulges. Bulge masses span $1.5\times 10^9$ to $1.4\times 10^{12}{M}_{\odot }$, with the most massive systems being ellipticals. Galaxy type matching shows that elliptical--elliptical (E--E) and elliptical--disc (E--D) mergers dominate over disc--disc (D--D) mergers. At least one galaxy in two-thirds of the dual AGN systems is elliptical and only $\sim$30% involve two disc galaxies. Although our sample is limited, our results suggest that dual AGN preferentially occur in evolved, red, quenched systems, that typically form via major mergers. They are predominantly hosted in classical bulges or elliptical galaxies rather than star-forming disc galaxies.

8 pages, 15 figures. Accepted for publication in MNRAS (30 October 2025)

References in corpus (22)

• Structural Properties of Pseudo-Bulges, Classical Bulges and Elliptical Galaxies: an SDSS Perspective
• The effect of galaxy mass ratio on merger--driven starbursts
• Secular- and merger-built bulges in barred galaxies
• A candidate sub-parsec binary black hole in the Seyfert galaxy NGC 7674
• Searching for Dual AGN in Galaxies with Double-Peaked Emission Line Spectra using Radio Observations
• A Catalog of 220 Offset and Dual AGNs: Increased AGN Activation in Major Mergers and Separations under 4 kpc
• Aging of galaxies along the morphological sequence, marked by bulge growth and disk quenching
• Constraints on Supermassive Black Hole Binaries from JWST and NANOGrav
• Galaxy Flybys: Evolution of the Bulge, Disk, and Spiral Arms
• A Spitzer Study of Pseudobulges in S0 Galaxies : Secular Evolution of Disks
• A Triple AGN in the NGC 7733-7734 Merging Group
• Dynamical Modelling and Emission Signatures of a Candidate Dual AGN with Precessing Radio Jets
• A Multi-wavelength Study of the Dual Nuclei in Mrk 212
• Bars and boxy/peanut bulges in thin and thick discs III. Boxy/peanut bulge formation and evolution in presence of thick discs
• Automated Detection of Double Nuclei Galaxies using GOTHIC and the Discovery of a Large Sample of Dual AGN
• Tracing the Evolution of Ultraluminous Infrared Galaxies into Radio Galaxies with Low Frequency Radio Observations
• Growth of disc-like pseudo-bulges in SDSS DR7 since z = 0.1
• Host galaxy magnitude of OJ 287 from its colours at minimum light
• Detection of the Fe K lines from the binary AGN in 4C+37.11
• Unveiling the kinematics of a central region in the triple AGN host NGC 7733-7734 interacting group
• Photometric properties of classical bulge and pseudo-bulge galaxies at $0.5\le z<1.0$
• Dual Active Galactic Nuclei in Nearby Galaxies