TY - JOUR

T1 - The Landscape of Galaxies Harboring Changing-look Active Galactic Nuclei in the Local Universe

AU - Dodd, Sierra A.

AU - Law-Smith, Jamie A. P.

AU - Auchettl, Katie

AU - Ramirez-Ruiz, Enrico

AU - Foley, Ryan J.

PY - 2021/1/25

Y1 - 2021/1/25

N2 - We study the properties of the host galaxies of changing-look active galactic nuclei (CL AGNs) with the aim of understanding the conditions responsible for triggering CL activity. We find that CL AGN hosts primarily reside in the so-called green valley that is located between spiral-like star-forming galaxies and dead ellipticals, implying that CL AGNs are activated during distinct periods of quenching and galaxy transformation processes. CL AGN hosts have low galaxy asymmetry indicators, suggesting that secular evolutionary processes (the influence of bars and spirals, and possibly minor mergers) might be the primary mechanism for transporting gas to the vicinity of the supermassive black hole (SMBH) rather than major mergers. Similar to tidal disruption events and highly variable AGNs, we find that CL AGN hosts are associated with SMBHs residing in high-density pseudo-bulges and appear to overlap most significantly with the population of low-ionization nuclear emission-line region galaxies. As such, CL AGNs are likely fueled by strong episodic bursts of accretion activity, which appear to take place preferentially as the amount of material accessible for star formation and accretion dwindles. We also identify that CL AGN hosts are characterized by either large Sersic indices or high bulge fractions, which suggests a simple metric for identifying candidates for spectroscopic follow-up observations in forthcoming synoptic surveys.

AB - We study the properties of the host galaxies of changing-look active galactic nuclei (CL AGNs) with the aim of understanding the conditions responsible for triggering CL activity. We find that CL AGN hosts primarily reside in the so-called green valley that is located between spiral-like star-forming galaxies and dead ellipticals, implying that CL AGNs are activated during distinct periods of quenching and galaxy transformation processes. CL AGN hosts have low galaxy asymmetry indicators, suggesting that secular evolutionary processes (the influence of bars and spirals, and possibly minor mergers) might be the primary mechanism for transporting gas to the vicinity of the supermassive black hole (SMBH) rather than major mergers. Similar to tidal disruption events and highly variable AGNs, we find that CL AGN hosts are associated with SMBHs residing in high-density pseudo-bulges and appear to overlap most significantly with the population of low-ionization nuclear emission-line region galaxies. As such, CL AGNs are likely fueled by strong episodic bursts of accretion activity, which appear to take place preferentially as the amount of material accessible for star formation and accretion dwindles. We also identify that CL AGN hosts are characterized by either large Sersic indices or high bulge fractions, which suggests a simple metric for identifying candidates for spectroscopic follow-up observations in forthcoming synoptic surveys.

KW - AGN host galaxies

KW - Active galactic nuclei

KW - Galaxy properties

KW - black hole physics

KW - Galaxy evolution

KW - Galaxy nuclei

KW - DIGITAL SKY SURVEY

KW - SUPERMASSIVE BLACK-HOLES

KW - STAR-FORMATION

KW - HOST GALAXIES

KW - OPTICAL VARIABILITY

KW - AGN

KW - EMISSION

KW - BROAD

KW - COEVOLUTION

KW - ENVIRONMENT

U2 - 10.3847/2041-8213/abd852

DO - 10.3847/2041-8213/abd852

M3 - Letter

VL - 907

JO - The Astrophysical Journal Letters

JF - The Astrophysical Journal Letters

SN - 2041-8205

IS - 1

M1 - L21

ER -