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

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Main Authors: Nehal, C. P., Das, Mousumi, Barway, Sudhanshu, Combes, Francoise, Biswas, Prerana, Bhattacharya, Anwesh, Saha, Snehanshu
Format: Preprint
Published: 2025
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author Nehal, C. P.
Das, Mousumi
Barway, Sudhanshu
Combes, Francoise
Biswas, Prerana
Bhattacharya, Anwesh
Saha, Snehanshu
author_facet Nehal, C. P.
Das, Mousumi
Barway, Sudhanshu
Combes, Francoise
Biswas, Prerana
Bhattacharya, Anwesh
Saha, Snehanshu
contents 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 $1.5\times10^9$ to $1.4\times10^{12}\,M_\odot$, 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.
format Preprint
id arxiv_https___arxiv_org_abs_2509_19548
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Investigating the Bulge Morphology of Dual AGN Host Galaxies from the GOTHIC survey
Nehal, C. P.
Das, Mousumi
Barway, Sudhanshu
Combes, Francoise
Biswas, Prerana
Bhattacharya, Anwesh
Saha, Snehanshu
Astrophysics of Galaxies
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 $1.5\times10^9$ to $1.4\times10^{12}\,M_\odot$, 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.
title Investigating the Bulge Morphology of Dual AGN Host Galaxies from the GOTHIC survey
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2509.19548