Galaxy pairs in the Sloan Digital Sky Survey – IX. Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer

By S. Satyapal, Sara L. Ellison, W. McAlpine, R. Hickox, David R. Patton, J. Trevor Mendel. 2014

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Interactions between galaxies are predicted to cause gas inflows that can potentially trigger nuclear activity. Since the inflowing material can obscu re the central regions of interacting galaxies, a potential limitation of previous optical st udies is that obscured Active Galactic Nuclei (AGNs) can be missed at various stages along the merger sequence. We present the first large mid-infrared study of AGNs in mergers and galaxy p airs, in order to quantify the incidence of obscured AGNs triggered by interactions. The sample consists of galaxy pairs and post-mergers drawn from the Sloan Digital Sky Survey that are matched to detections by the Wide Field Infrared Sky Explorer (WISE). We find that the fraction of AGN in the pairs, relative to a mass-, redshift- and environment-matc hed control sample, increases as a function of decreasing projected separation. This enhancement is most dramatic in the postmerger sample, where we find a factor of 10-20 excess in the AGN fraction compared with the control. Although this trend is in qualitative agreemen t with results based on optical AGN selection, the mid-infrared selected AGN excess increases much more dramatically in the post-mergers than is seen for optical AGN. Our results suggest that energetically dominant optically obscured AGNs become more prevalent in the most advanced mergers, consistent with theoretical predictions.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/51afdd7f3c82a928eac9db7a3af77455bf657fc5

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Citations in the corpus

Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey (2017, background): “Indeed, the fraction of AGN is seen to fall dramatically at large projected separations (e.g., Ellison et al. 2013; Satyapal et al. 2014a; Ricci et al. 2017).”
Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured (2017, background): “In agreement with this idea, Treister et al. (2012) found that the fraction of AGN in mergers increases with the AGN luminosity (see also Bessiere et al. 2012; Schawinski et al. 2012; Hickox et al. 2014; Glikman et al. 2015), and observations of optically-selected (Ellison et al. 2011), IR-selected ”