MAJOR GALAXY MERGERS ONLY TRIGGER THE MOST LUMINOUS ACTIVE GALACTIC NUCLEI

By E. Treister, Kevin Schawinski, C. Urry, B. Simmons. 2012

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Using multiwavelength surveys of active galactic nuclei (AGNs) across a wide range of bolometric luminosities (1043 < Lbol (erg s−1) <5 × 1046) and redshifts (0 < z < 3), we find a strong, redshift-independent correlation between the AGN luminosity and the fraction of host galaxies undergoing a major merger. That is, only the most luminous AGN phases are connected to major mergers, while less luminous AGNs appear to be driven by secular processes. Combining this trend with AGN luminosity functions to assess the overall cosmic growth of black holes, we find that ∼50% by mass is associated with major mergers, while only 10% of AGNs by number, the most luminous, are connected to these violent events. Our results suggest that to reach the highest AGN luminosities—where the most massive black holes accreted the bulk of their mass—a major merger appears to be required. The luminosity dependence of the fraction of AGNs triggered by major mergers can successfully explain why the observed scatter in the M–σ relation for elliptical galaxies is significantly lower than in spirals. The lack of a significant redshift dependence of the Lbol–fmerger relation suggests that downsizing, i.e., the general decline in AGN and star formation activity with decreasing redshift, is driven by a decline in the frequency of major mergers combined with a decrease in the availability of gas at lower redshifts.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/06e94cd53d1476614f97205198a550ae78028c74

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Citations in the corpus

Galaxy pairs in the Sloan Digital Sky Survey – VIII. The observational properties of post-merger galaxies (2013, background): “Recently, Treister et al. (2012) found a correlation between the fraction of AGN associated with mergers and bolometric luminosity, claiming that mergers only trigger the most luminous AGN.”
SUBMILLIMETER GALAXIES AS PROGENITORS OF COMPACT QUIESCENT GALAXIES (2014, background): “…of the most luminous QSOs, i.e those likely associated with the formation of massive quiescent galaxies, are found to be primarily major mergers (Treister et al. 2012; Riechers et al. 2008), a result which is cooborated by Olsen et al. (2013) who find that luminous AGN in massive z ∼ 2 galaxies…”
BLACK HOLE VARIABILITY AND THE STAR FORMATION–ACTIVE GALACTIC NUCLEUS CONNECTION: DO ALL STAR-FORMING GALAXIES HOST AN ACTIVE GALACTIC NUCLEUS? (2013, result): “Other results have suggested that fmerge increases at very high LAGN (e.g., Urrutia et al. 2008) leading to the conclusion that black hole growth can be triggered by major interactions, but only at the highest luminosities (Schawinski et al. 2012; Treister et al. 2012).”
UNLEASHING POSITIVE FEEDBACK: LINKING THE RATES OF STAR FORMATION, SUPERMASSIVE BLACK HOLE ACCRETION, AND OUTFLOWS IN DISTANT GALAXIES (2013, background): “…important for the most extreme star formation rates observed at high redshift, and are important locally in accounting for ULIRGs, they are likely subdominant at high redshift both in triggering the bulk of star formation (Kartaltepe et al. 2012) and in triggering AGNs (Treister et al. 2012).”
COMPTON-THICK ACCRETION IN THE LOCAL UNIVERSE (2015, background): “This phase could be associated with a period of rapid SMBH accretion, and could be part of an evolutionary scenario that starts with major galaxy mergers and ends with an unobscured SMBH (e.g., Sanders et al. 1988; Treister et al. 2012).”
Tracing the cosmic growth of supermassive black holes to z ∼ 3 with Herschel (2014, background): “Nevertheless, recent works (Treister et al. 2012; Schawinski et al. 2012; Laird et al. 2010) claim that the host galaxies of highredshift (z >1–2) AGN could have experienced intense bursts of star formation (e.g. Sub-Millimeter Galaxies, SMGs and/or UltraLuminous Infrared galaxies, ULIRGs), likely…”
Cosmic X-ray surveys of distant active galaxies (2015, background): “…evidence that the most luminous AGNs are preferentially triggered by major mergers, as also found for the most powerful star-forming galaxies (e.g., Treister et al 2012; Kartaltepe et al 2012), which could indicate that major mergers are required to drive sufficient quantities of gas into the…”
Morphologies of z ∼ 0.7 AGN host galaxies in CANDELS: no trend of merger incidence with AGN luminosity (2014, methodology): “Treister et al. (2012) studied the incidence of merger features as a function of AGN luminosity and found that the highest luminosity AGN have higher incidences of mergers.”
The green valley is a red herring: Galaxy Zoo reveals two evolutionary pathways towards quenching of star formation in early-and late-type galaxies (2014, background): “The majority of black holes growing locally and at high redshift are hosted in late-type galaxies, clearly driven by secular processes rather than major mergers (e.g. Schawinski et al. 2010a, 2011, 2012; Cisternas et al. 2011; Kocevski et al. 2012; Simmons et al. 2012; Treister et al. 2012).”
Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey (2017, background): “…1–2 quasars have revealed these AGN to be overwhelmingly hosted by galaxy mergers (e.g., Urrutia et al. 2008; Glikman et al. 2012, 2015), possibly suggesting that the most luminous BH growth is increasingly likely to be triggered by galaxy interactions (e.g., Treister et al. 2012; Fan et al. 2016).”