THE BULK OF THE BLACK HOLE GROWTH SINCE z ∼ 1 OCCURS IN A SECULAR UNIVERSE: NO MAJOR MERGER–AGN CONNECTION

By M. Cisternas, K. Jahnke, K. Inskip, J. Kartaltepe, A. Koekemoer, T. Lisker, A. Robaina, M. Scodeggio, K. Sheth, J. Trump and 14 more. 2010

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What is the relevance of major mergers and interactions as triggering mechanisms for active galactic nuclei (AGNs) activity? To answer this long-standing question, we analyze 140 XMM-Newton-selected AGN host galaxies and a matched control sample of 1264 inactive galaxies over z ∼ 0.3–1.0 and M* < 1011.7 M☉ with high-resolution Hubble Space Telescope/Advanced Camera for Surveys imaging from the COSMOS field. The visual analysis of their morphologies by 10 independent human classifiers yields a measure of the fraction of distorted morphologies in the AGN and control samples, i.e., quantifying the signature of recent mergers which might potentially be responsible for fueling/triggering the AGN. We find that (1) the vast majority (>85%) of the AGN host galaxies do not show strong distortions and (2) there is no significant difference in the distortion fractions between active and inactive galaxies. Our findings provide the best direct evidence that, since z ∼ 1, the bulk of black hole (BH) accretion has not been triggered by major galaxy mergers, therefore arguing that the alternative mechanisms, i.e., internal secular processes and minor interactions, are the leading triggers for the episodes of major BH growth. We also exclude an alternative interpretation of our results: a substantial time lag between merging and the observability of the AGN phase could wash out the most significant merging signatures, explaining the lack of enhancement of strong distortions on the AGN hosts. We show that this alternative scenario is unlikely due to (1) recent major mergers being ruled out for the majority of sources due to the high fraction of disk-hosted AGNs, (2) the lack of a significant X-ray signal in merging inactive galaxies as a signature of a potential buried AGN, and (3) the low levels of soft X-ray obscuration for AGNs hosted by interacting galaxies, in contrast to model predictions.

Subfields: Astronomy and Astrophysics, Computer Vision and Pattern Recognition

View Paper: https://www.semanticscholar.org/paper/11064657a9918d7155bc8c5adc4756c3e0866712

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Citations in the corpus

The Coevolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe (2014, background): “At lower redshifts (z ∼ 0.7), Cisternas et al. (2011) analyzed HST images of the hosts of AGN with X-ray luminosities of 1043 to 1044 erg/s.”
Adaptive Optics for Astronomy (2012, result): “…the origin of the double peaked line profiles may lie in other processes such as outflows or jet-cloud interactions; and Rosario et al. (2011) suggest that most QSOs may not be associated with gas rich major mergers, an idea that is gaining weight from other observations (Cisternas et al. 2011).”
Galaxy pairs in the Sloan Digital Sky Survey - IV: Interactions trigger AGN (2011, background): “…sole AGN trigger (e.g. Li et al. 2006; Lutz et al. 2010; Mullaney et al. 2011), which may play a role in explaining why many imaging surveys of AGN hosts detect no signs of (an excess of) recent merger activity (e.g. Grogin et al. 2005; Gabor et al.2009; Cisternas et al 2011; Kocevski et al. 2011).”
A CORRELATION BETWEEN STAR FORMATION RATE AND AVERAGE BLACK HOLE ACCRETION IN STAR-FORMING GALAXIES (2013, background): “One is that the SF in disk galaxies tends to concentrate in their disks, which leads to a BHAR to galaxy-wide SFR ratio lower than that inferred by the observedMBH andMBulge (e.g. Jahnke et al. 2009; Cisternas et al. 2011a,b; Rafferty et al. 2011).”
Enhanced star formation rates in AGN hosts with respect to inactive galaxies from PEP-Herschel observations (2012, background): “2005; Gabor et al. 2009; Cisternas et al. 2011), and are frequently found in disks at high redshifts (Schawinski et al. 2011; Kocevski et al. 2012).”
What drives the growth of black holes (2011, background): “…of the X-ray AGNs out to z ≈ 3 clearly reside in galaxy major mergers (≈ 15–20%; e.g., Sánchez et al. 2004; Pierce et al. 2007; Georgakakis et al. 2009; Cisternas et al. 2011; Kocevski et al. 2011, comparable to that found for X-ray selected AGNs in the local Universe (e.g., Koss et al. 2010; see…”
Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey (2017, background): “Furthermore, at similar redshifts, AGN with more moderate luminosities (LAGN ∼ 1043 − 1044 erg s−1) also appear no more likely to show interaction signatures than non-AGN systems (e.g., Cisternas et al. 2011; Schawinski et al. 2011; Kocevski et al. 2012).”
Growth and activity of black holes in galaxy mergers with varying mass ratios (2014, result): “Cisternas et al. (2011) perform a similar study and reach the same conclusions, by visually inspecting the morphologies of 140 AGN hosts and of 1264 inactive galaxies, finding a lack of strong distortions in more than 85 per cent of the AGN hosts, and similar distortion fractions between active and…”
Theoretical Challenges in Galaxy Formation (2016, background): “…at low and high redshift also provide evidence that significant black hole accretion is not solely connected to merging but also gas rich disk like galaxies can host AGN of significant luminosity (Cisternas et al. 2011, Georgakakis et al. 2009, Kocevski et al. 2012, Schawinski et al. 2011).”
CANDELS: CONSTRAINING THE AGN–MERGER CONNECTION WITH HOST MORPHOLOGIES AT z ∼ 2 (2011, background): “More recently, Gabor et al. (2009) and Cisternas et al. (2011) examined the host morphologies of AGNs selected in the Cosmic Evolution Survey (COSMOS; Scoville et al. 2007) and report that the disturbed fraction among active and quiescent galaxies at z ∼ 1 is not significantly different.”
The quest for dual and binary supermassive black holes: A multi-messenger view (2019, result): “However, there are investigations revealing no enhanced AGN activity in mergers compared to a matched control sample of inactive galaxies (e.g. Cisternas et al., 2011; Mechtley et al., 2016).”
THE NON-CAUSAL ORIGIN OF THE BLACK-HOLE–GALAXY SCALING RELATIONS (2010, background): “…there were enough mergers to average out the extreme MBH/M∗ systems – at lower z, with a decaying gas reservoir and merger rate and the transition to a “secular universe” (see e.g. Cisternas et al. 2011), the prerequisites for producing new extreme values become less and less frequently fulfilled.”
Kiloparsec-scale outflows are prevalent among luminous AGN: outflows and feedback in the context of the overall AGN population (2014, background): “The number ofmajor mergersobserved in AGN is much lower (e.g., Cisternas et al. 2011).”
The mean star formation rate of X-ray selected active galaxies and its evolution from z~2.5: results from PEP-Herschel (2012, background): “Studies of moderate luminosity X-rayAGNs find no excess of merger signatures compared to inactive galaxies (e.g. Grogin et al. 2005), and only weak trends with AGN luminosity (Cisternas et al. 2011; Kocevski et al. 2012).”
Morphologies of z ∼ 0.7 AGN host galaxies in CANDELS: no trend of merger incidence with AGN luminosity (2014, background): “While many studies rely on human classifiers (e.g. Cisternas et al. 2011; Kocevski et al. 2012; Treister et al. 2012), using quantitative measures enables us to detect more subtle levels of disturbance (Conselice et al. 2000; Lotz et al. 2010a,b) as well as allow more detailed statistical analysis…”
GOODS-Herschel: the far-infrared view of star formation in active galactic nucleus host galaxies since z ≈ 3 (2011, methodology): “1 AGN-hosting galaxies with those of the general galaxy population, Cisternas et al. (2011) showed that the same fraction of each sample showed signs of recent or ongoing mergers, while Schawinski et al. (2011) used a subsample of 28 X-ray AGNs in the CDFS to show that this was also likely the case…”