SDSS-IV MaNGA: How Galaxy Interactions Influence Active Galactic Nuclei

Abstract

We present a comparative study of active galactic nuclei (AGN) between galaxy pairs and isolated galaxies with the final data release of the MaNGA integral field spectroscopic survey. We build a sample of 391 kinematic galaxy pairs within the footprint of the survey and select AGN using the survey's spectra. We use the comoving volume densities of the AGN samples to quantify the effects that tidal interactions have on the triggering of nuclear accretion. Our hypothesis is that the pair sample contains AGN that are triggered by not only stochastic accretion but also tidally induced accretion and correlated accretion. With the level of stochastically triggered AGN fixed by the control sample, we model the strength of tidally induced accretion and correlated accretion as a function of projected separation (r p ) and compare the model expectations with the observed volume densities of dual AGN and offset AGN (single AGN in a pair). At r p ∼ 10 kpc, we find that tidal interactions induce ∼30% more AGN than stochastic fueling and cause ∼12% of the offset AGN to become dual AGN because of correlations. The strength of both these effects decreases with increasing r p . We also find that the [O iii] luminosities of the AGN in galaxy pairs are consistent with those found in isolated galaxies, likely because stochastically fed AGN dominate even among close pairs. Our results illustrate that while we can detect tidally induced effects statistically, it is challenging to separate tidally induced AGN and stochastically triggered AGN in interacting galaxies.

A Census of WISE-selected Dual and Offset AGNs Across the Sky: New Constraints on Merger-driven Triggering of Obscured AGNs

“…The relatively stronger excess among the dual AGNs at small ΔS (factors of ∼3 and 7 for obscured and unobscured AGNs, respectively) can be explained by correlated triggering, i.e., that the likelihood of one AGN being triggered increases the likelihood of the other being triggered during late merger stages. This distinction between offset and dual AGNs was also shown in Fu et al (2018) and Steffen et al (2023) for nearby optically selected AGNs (based on narrow emission line diagnostics), and here we show it exists for relatively more-luminous WISE AGNs as well. For direct comparison, we compute the separation-dependent correlated fraction as in Steffen et al (2023).…”

“…This distinction between offset and dual AGNs was also shown in Fu et al (2018) and Steffen et al (2023) for nearby optically selected AGNs (based on narrow emission line diagnostics), and here we show it exists for relatively more-luminous WISE AGNs as well. For direct comparison, we compute the separation-dependent correlated fraction as in Steffen et al (2023). This procedure estimates that 18% of pairs with only one AGN become dual AGNs due to correlated triggering (similar to, but larger than, the fraction of 11.5% for optically selected AGNs from Steffen et al 2023).…”

“…Indeed, previous results have shown that the AGN merger fraction (for X-ray and/or MIR-selected AGNs) increases toward smaller pair separations (e.g., Barrows et al 2017a;Stemo et al 2021). Moreover, comparison to control samples of inactive galaxies have generally revealed that mergers have an excess of AGNs at increasingly later merger stages (e.g., Ellison et al 2011Ellison et al , 2013Satyapal et al 2014;Fu et al 2018;Shah et al 2020;Steffen et al 2023). However, these results are limited to systems where offset versus dual AGNs cannot be distinguished, or otherwise to nearby optically selected samples for which the dependence on AGN obscuration cannot be determined.…”

“…From the galaxy sample, we first compute the observed number of offset AGNs, dual AGNs, and galaxy pairs as a function of ΔS. To create a volume-limited sample, similar to Fu et al (2018) and Steffen et al (2023), we normalize the probabilities of each pair by the volume weights (V max ). Doing so yields volume densities for the offset AGNs, dual AGNs, offset plus dual AGNs, and galaxy pairs: N oAGN,V , N dAGN,V , N o+dAGN,V , and N Gal−Gal,V , respectively.…”

“…These estimates are obtained by computing the fraction of the galaxy sample that host WISE AGNs. Following the procedure from Fu et al (2018) and Steffen et al (2023), this fraction is parameterized as a log-normal function of host stellar mass and redshift. This function is then applied to components "a" and "b" of each galaxy pair to determine the probability it hosts a WISE AGN: f AGN,a and `fAGN,b .…”