THE BULK OF THE BLACK HOLE GROWTH SINCE<i>z</i>∼ 1 OCCURS IN A SECULAR UNIVERSE: NO MAJOR MERGER-AGN CONNECTION

Cisternas, Mauricio; Jahnke, K.; Inskip, K. J.; Kartaltepe, Jeyhan S.; Koekemoer, Anton M.; Lisker, Thorsten; Robaina, Aday R.; Scodeggio, M.; Sheth, Kartik; Trump, Jonathan R.; Andrae, R.; Miyaji, Takeshi; Lusso, Elisabeta; Brusa, M.; Capak, P.; Cappelluti, N.; Civano, F.; Ilbert, O.; Impey, C. D.; Leauthaud, Alexie; Lilly, S. J.; Salvato, M.; Scoville, N. Z.; Taniguchi, Y.

doi:10.1088/0004-637x/726/2/57

Cited by 350 publications

(311 citation statements)

References 139 publications

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“…Bessiere et al (2012), however, find QSOs at several stages of the merging process even before the final merger. On the other hand, Cisternas et al (2011) show that AGNs do not lie in more disturbed hosts and conclude that mergers are not necessarily responsible for nuclear activity. Teng et al (2012) search for double QSOs in pairs of galaxies where one member is already known to host an AGN and find only one such case out of twelve objects.…”

Section: Discussionmentioning

confidence: 86%

Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

Propris

Baldry

Bland-Hawthorn

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We derive the close pair fractions and volume merger rates for galaxies in the GAMA survey with −23 < M r < −17 (Ω M = 0.27, Ω Λ = 0.73, H 0 = 100 km s −1 Mpc −1 ) at 0.01 < z < 0.22 (lookback time of < 2 Gyr). The merger fraction is approximately 1.5% per Gyr at all luminosities (assuming 50% of pairs merge) and the volume merger rate is ≈ 3.5 × 10 −4 Mpc −3 Gyr −1 . We examine how the merger rate varies by luminosity and morphology. Dry mergers (between red/spheroidal galaxies) are found to be uncommon and to decrease with decreasing luminosity. Fainter mergers are wet, between blue/disky galaxies. Damp mergers (one of each type) follow the average of dry and wet mergers. In the brighter luminosity bin (−23 < M r < −20) the merger rate evolution is flat, irrespective of colour or morphology, out to z ∼ 0.2. The makeup of the merging population does not appear to change over this redshift range. Galaxy growth by major mergers appears comparatively unimportant and dry mergers are unlikely to be significant in the buildup of the red sequence over the past 2 Gyr. We compare the colour, morphology, environmental density and degree of activity (BPT class) of galaxies in pairs to those of more isolated objects in the same volume. Galaxies in close pairs tend to be both redder and slightly more spheroid-dominated than the comparison sample. We suggest that this may be due to 'harassment' in multiple previous passes prior to the current close interaction. Galaxy pairs do not appear to prefer significantly denser environments. There is no evidence of an enhancement in the AGN fraction in pairs, compared to other galaxies in the same volume

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Section: Discussionmentioning

confidence: 86%

Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

Propris

Baldry

Bland-Hawthorn

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…At low redshifts, we compare with the PG quasar sample of Dunlop et al (2003); Floyd et al (2004) (we plot the fraction with best-fit bulge-to-total mass ratio B/T < 0.5 in bins of Lbol, estimated from the observed nuclear Vband luminosities, with Poisson errors). At z ∼ 0.5 − 1, we compare the low-luminosity sample from COSMOS studied in Gabor et al (2009) and Cisternas et al (2011); we plot the "final" quoted fraction of disk-dominated galaxies in the sample (with the approximate ∼ 10% systematic difference between classifiers quoted therein) and 90% range of Lbol estimated from the hard X-ray luminosities. We also compare the sample of true quasars in Zakamska et al (2006Zakamska et al ( , 2008; Liu et al (2009) at z ∼ 0.3 − 0.7.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, recent observations of AGN host morphologies and colors have suggested that major mergers probably do not fuel most low and intermediate-luminosity AGN, as a large fraction appear in "normal" disks (Gabor et al 2009;Schawinski et al 2011;Cisternas et al 2011;Kocevski et al 2012;Rosario et al 2011;Civano et al 2012;Santini et al 2012;Mullaney et al 2012;Treister et al 2012). This should perhaps not be surprising.…”

Section: Introductionmentioning

confidence: 99%

Do we expect most AGN to live in discs?

Hopkins¹,

Kocevski²,

Bundy³

2014

Monthly Notices of the Royal Astronomical Society

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Recent observations have indicated that a large fraction of the low to intermediate luminosity AGN population lives in disk-dominated hosts, while the more luminous quasars live in bulge-dominated hosts (that may or may not be major merger remnants), in conflict with some previous model predictions. We therefore build and compare a semi-empirical model for AGN fueling which accounts for both merger and non-merger "triggering." In particular, we show that the "stochastic accretion" model -in which fueling in disk galaxies is essentially a random process arising whenever dense gas clouds reach the nucleusprovides a good match to the present observations at low/intermediate luminosities. However it falls short of the high-luminosity population. We combine this with models for major merger-induced AGN fueling, which lead to rarer but more luminous events, and predict the resulting abundance of disk-dominated and bulge-dominated AGN host galaxies as a function of luminosity and redshift. We compile and compare observational constraints from z ∼ 0 − 2. The models and observations generically show a transition from disk to bulge dominance in hosts near the Seyfert-quasar transition, at all redshifts. "Stochastic" fueling dominates AGN by number (dominant at low luminosity), and dominates BH growth below the "knee" in the present-day BH mass function ( 10 7 M ). However it accounts for just ∼ 10% of BH mass growth at masses 10 8 M . In total, fueling in disky hosts accounts for ∼ 30% of the total AGN luminosity density/BH mass density. The combined model also accurately predicts the AGN luminosity function and clustering/bias as a function of luminosity and redshift; however, we argue that these are not sensitive probes of BH fueling mechanisms.

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“…The discovery of double AGNs (e.g., Hennawi et al 2010;McGurk et al 2011) adds support to a merger origin of the AGN activity. On the other hand, various observational studies suggest that moderately luminous AGN are typically not major-merger-driven at z < ∼ 1 (Salucci et al 1999;Grogin et al 2005;Pierce et al 2007;Georgakakis et al 2009;Cisternas et al 2011;Villforth et al 2014), and interestingly also at z ≈ 2 (Rosario et al 2013a;Silverman et al 2011;Kocevski et al 2012). Bournaud et al (2012) find a correlation between the presence of violent instabilities and AGN activity in gas-rich galaxies at high redshift, thanks to the presence of giant clumps of gas in the disk.…”

Section: Introductionmentioning

confidence: 99%

Triggering active galactic nuclei in hierarchical galaxy formation: disk instability vs. interactions

Menci

Gatti

Fiore

et al. 2014

A&A

141

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Using a state-of-the-art semi analytic model for galaxy formation, we investigated in detail the effects of black hole (BH) accretion triggered by disk instabilities (DI) in isolated galaxies on the evolution of the AGN population. Specifically, we took on, developed, and expanded the Hopkins & Quataert (2011, MNRAS, 411, 1027 model for the mass inflow following disk perturbations, based on a physical description of nuclear inflows and tested against aimed N-body simulations. We compared the evolution of AGN due to such a DI accretion mode with that arising in a scenario where galaxy interactions (IT mode) produce the sudden destabilization of large quantities of gas feeding the AGN; this constitutes the standard AGN feeding mode implemented in the earliest versions of most semi-analytic models. To study the maximal contribution of DI to the evolution of the AGN population, we extended and developed the DI model to assess the effects of changing the assumed disk surface density profile, and to obtain lower limits for the nuclear star formation rates associated to the DI accretion mode. We obtained the following results: i) For AGN with luminosity M 1450 > ∼ −26, the DI mode can provide the BH accretion needed to match the observed AGN luminosity functions up to z ≈ 4.5. In such a luminosity range and redshift, it constitutes a viable candidate mechanism to fuel AGN, and can compete with the IT scenario as the main driver of cosmological evolution of the AGN population. ii) The DI scenario cannot provide the observed abundance of high-luminosity QSO with M 1450 ≤ −26 AGN, as well as the abundance of high-redhshift z > ∼ 4.5 QSO with M 1450 ≤ −24. As found in our earliest works, the IT scenario provides an acceptable match to the observed luminosity functions up to z ≈ 6. iii) The dispersion of the distributions of Eddington ratio λ for low-and intermediate-luminosity AGN (bolometric L AGN = 10 43 −10 45 erg s −1 ) is predicted to be much smaller in the DI scenario compared to the IT mode. iv) The above conclusions concerning the DI mode are robust with respect to the explored variants of the DI model. We discuss the physical origin of our findings. Finally, we discuss how it is possible to pin down the dominant fueling mechanism of AGN in the low-intermediate luminosity range M 1450 > ∼ −26 where the DI and the IT modes are both viable candidates as the main drivers of the AGN evolution. We show that an interesting discriminant could be provided by the fraction of AGN with high Eddington ratios λ ≥ 0.5, since it increases with luminosity in the IT case, while the opposite is true in the DI scenario.

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THE BULK OF THE BLACK HOLE GROWTH SINCEz∼ 1 OCCURS IN A SECULAR UNIVERSE: NO MAJOR MERGER-AGN CONNECTION

Cited by 350 publications

References 139 publications

Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

Do we expect most AGN to live in discs?

Triggering active galactic nuclei in hierarchical galaxy formation: disk instability vs. interactions

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