SDSS-IV MaNGA - The Incidence of Major Mergers in type I and II AGN Host Galaxies in the DR15 sample - Study on merger impact and AGN triggering

Aug 21, 2026

Study quantifies how major mergers relate to triggering nuclear activity in a MaNGA DR15 sample, using 47 type I and 236 type II optically selected AGN. Non-parametric image predictors (including Gini, M20, concentration, asymmetry, clumpiness, Sérsic index, and shape asymmetry) are combined with Linear Discriminant Analysis to identify merger stages, then verified through bright tidal features in post-processed SDSS and DESI legacy images. Major mergers occur at 29% ± 3% versus 22% ± 0.8% in a matched non-AGN control, with post-coalescence dominating. AGN activity levels in massive mergers match prior [OIII]-based results, while similar levels arise in bar-hosting systems, implying mergers promote but do not exclusively determine AGN activation. Tidal strength shows no significant environmental effect, and a H-H* diagram supports an empirical AGN flux predictor for correcting photometric quantities in large surveys.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages23

Reading Time58 min

AccessFree to download

Abstract

1 Introduction

Dynamical interactions and mergers

Minor mergers and co-evolution

Secular instabilities and bars

Study aim and sample selection

arXiv :2305 .03834v1 [ astro-ph .GA] 5 May 2023 SDSS-IV MaNGA:The Incidence of Major Mergers in type I and II AGN Host Galaxies in the DR15 sample. Hernández-Toledo H.M 1★ , Cortes-Suárez E.1 , Vázquez-Mata J. A.2 , Nevin R.3 , Ávila-Reese V.1 , Ibarra-Medel H.4,5 , Negrete C. A.6 1 Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, 04510 CDMX, Mexico 2 Departamento de Física, Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, CDMX, 04510, México 3 Fermi National Accelerator Laboratory, Batavia, IL 60510, USA 4 Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, U.P. Adolfo López Mateos, C.P. 07738, Ciudad de México, México 5 Instituto de Astronomía y Ciencias Planetarias, Universidad de Atacama, Copayapu 485, Copiapó, Chile 6 CONACyT Research Fellow – Instituto de Astronomía, Universidad Nacional Autónoma de México, A.P. 70-264, 04510 CDMX, Mexico Accepted XXX. Received YYY; in original form ZZZ ABSTRACT We present a study on the incidence of major mergers and their impact on the triggering of nuclear activity in 47 type I and 236 type II optically-selected AGN from the MaNGA DR15 sample. From an estimate of non-parametric image predictors (􀀜􀀸􀀽􀀸 , M20 , concentration (C), asymmetry (A), clumpiness (S), Sérsic index (n), and shape asymmetry(􀀖 􀀨)) using the SDSS images, in combination with a Linear Discriminant Analysis Method, we identiﬁed major mergers and merger stages. We reinforced our results by looking for bright tidal features in our post-processed SDSS and DESI legacy images. We ﬁnd a statistically signiﬁcant higher incidence of major mergers of 29% ± 3% in our type I+II AGN sample compared to 22% ± 0.8% for a non-AGN sample matched in redshift, stellar mass, color and morphological type, ﬁnding also a prevalence of post-coalescence (51% ± 5%) over pre-coalescence (23% ± 6%) merger stages. The levels of AGN activity among our massive major mergers are similar to those reported in other works using [Oiii] tracers. However, similar levels are produced by our AGN-galaxies hosting stellar bars, suggesting that major mergers are important promoters of nuclear activity but are not the main nor the only mechanism behind the AGN triggering. The tidal strength parameter 􀀦 was considered at various scales looking for environmental diﬀerences that could aﬀect our results on the merger incidence, ﬁnding non-signiﬁcant diﬀerences. Finally, the H-H􀁖 diagram could be used asan empirical predictor for the ﬂux coming from an AGN source, useful to correct photometric quantities in large AGN samples emerging from surveys. Key words: galaxies: nuclei – quasars: emission lines – galaxies: interactions – galaxies: photometry 1 INTRODUCTION Dynamical interactions and mergers, which promote gas infall, are among the main mechanisms suggested to drive the growth of supermassive black holes (SMBHs) in the nuclear regions of galaxies (e.g., Di Matteo et al. 2005; Springel et al. 2005) . Tidal torques from major mergers can drive gas accretion for fueling both star formation (Mihos & Hernquist 1994, 1996) and SMBH growth (Di Matteo et al. 2005; Hopkins et al. 2005; Ellison et al. 2011; Koss et al. 2012; Treister et al. 2012; Satyapal et al. 2014) . Minor mergers are also thought among the most important mechanism for SMBH growth, simultaneously inducing morphological perturbations and stimulating star formation (e.g., Noeske et al. 2007; Daddi et al. 2007; Cisternas et al. 2011; Kocevski et al. 2012; Kaviraj 2014; Villforth et al. 2017) . The tight correlations between SMBH mass and galaxy properties suggest co-evolution between them, with mergers possibly being the com- ★ [E-mail: hector@astro.unam.mx](E-mail: hector@astro.unam.mx) mon cause of both SMBH accretion (with the consequent trigger of the AGN) and bulge mass buildup (Hopkins et al. 2007) . Under these scenarios and depending on the initial conditions, galaxies hosting ac

FAQs

What data sample and AGN types are analyzed in this study?

The analysis uses 47 type I and 236 type II optically selected AGN from the MaNGA DR15 sample, and comparisons are made to a non-AGN control matched in redshift, stellar mass, color, and morphology.

How are major mergers and merger stages identified?

The work estimates major mergers and merger stages using non-parametric image predictors from SDSS images combined with a Linear Discriminant Analysis method, then reinforces results by searching for bright tidal features in post-processed SDSS and DESI legacy images.

Do major mergers uniquely trigger AGN activity?

No. While major mergers show a higher incidence in the AGN sample, similar AGN activity levels also occur in galaxies hosting stellar bars, indicating mergers promote nuclear activity but are not the only nor the main mechanism behind AGN triggering.

Aug 21, 2026

Upload by 8796093062539