Morphologies of z ∼ 0.7 AGN host galaxies in CANDELS: no trend of merger incidence with AGN luminosity

By C. Villforth, F. Hamann, D. Rosario, P. Santini, E. McGrath, A. van der Wel, Yu-Yen Chang, Yicheng Guo, T. Dahlén, Eric F. Bell and 17 more. 2014

134 citations recorded by the source corpus.

The processes that trigger active galactic nuclei (AGN) remain poorly understood. While lower luminosity AGN may be triggered by minor disturbances to the host galaxy, stronger disturbances are likely required to trigger luminous AGN. Major wet mergers of galaxies are ideal environments for AGN triggering since they provide large gas supplies and galaxy scale torques. There is however little observational evidence for a strong connection between AGN and major mergers. We analyse the morphological properties of AGN host galaxies as a function of AGN and host galaxy luminosity and compare them to a carefully matched sample of control galaxies. AGN are X-ray selected in the redshift range 0.5 < z < 0.8 and have luminosities 41 ≲ log (L_X [erg s^(−1)]) ≲ 44.5. ‘Fake AGN’ are simulated in the control galaxies by adding point sources with the magnitude of the matched AGN. We find that AGN host and control galaxies have comparable asymmetries, Sersic indices and ellipticities at rest frame ∼950 nm. AGN host galaxies show neither higher average asymmetries nor higher fractions of very disturbed objects. There is no increase in the prevalence of merger signatures with AGN luminosity. At 95 per cent confidence we find that major mergers are responsible for <6 per cent of all AGN in our sample as well as <40 per cent of the highest luminosity AGN (log (L_X [erg s^(−1)]) ∼ 43.5). Major mergers therefore either play only a very minor role in the triggering of AGN in the luminosity range studied or time delays are too long for merger features to remain visible.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/a7f1fe902c03c09e181e8e06615edfb70f1e933d

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

Cosmic X-ray surveys of distant active galaxies (2015, background): “%) of the AGN population over the broad redshift range of z ≈ 0.2–2.5 were found to have the clear signatures expected for major mergers (disturbed host-galaxy morphologies and tidal tails; Silverman et al 2011; Cisternas et al 2011; Kocevski et al 2012; Böhm et al 2013; Villforth et al 2014).”
Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey (2017, background): “…results (e.g. Gabor et al. 2009; Cisternas et al. 2011; Schawinski et al. 2011; Kocevski et al. 2012; Treister et al. 2012; Ellison et al. 2013; Villforth et al. 2014; Kocevski et al. 2015), often finding that the host galaxies of AGN are similar to those of non-AGN (i.e., no strong…”
Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured (2017, background): “Some recent studies of galaxies at z ∼ 0.6 − 0.7 (e.g., Villforth et al. 2014, 2016) have argued that the fraction of AGN in mergers is significantly lower, and it does not increase with the AGN bolometric luminosity.”