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Changing-look active galactic nuclei (CL-AGN) have been observed to change optical spectral type. Mrk 1018 is unique: first classified as a type 1.9 Seyfert galaxy, it transitioned to a type 1 before returning to its initial classification…

Active galactic nucleus (AGN)-driven gas outflows are one of the best tracers of AGN feedback in action, as these powerful outflows expel/heat or compress the surrounding interstellar medium (ISM), thus quenching or enhancing star-forming…

Astrophysics of Galaxies · Physics 2026-02-10 Ruisong Xia , Chen Qin , Huynh Anh N. Le , Yongquan Xue , Shifu Zhu , Mengqiu Huang , Hao Liu , Xiaozhi Lin

Although now routinely incorporated into hydrodynamic simulations of galaxy evolution, the true importance of the feedback effect of the outflows driven by active galactic nuclei (AGN) remains uncertain from an observational perspective.…

Context: Variations in the mass accretion rate appear to be responsible for the rapid transitions in spectral type that are observed in increasingly more active galactic nuclei (AGNs). These objects are now labeled "changing-look" AGNs and…

Astrophysics of Galaxies · Physics 2020-04-15 F. Marin , D. Hutsemékers

Changing-look phenomenon observed now in a growing number of active galaxies challenges our understanding of the accretion process close to a black hole. We propose a simple explanation for periodic outbursts in sources operating at a few…

Astrophysics of Galaxies · Physics 2021-02-02 Marzena Śniegowska , Bożena Czerny

We review the results from multi-dimensional, time-dependent simulations of gas dynamics in AGN. We will focus on two types of outflows powered by radiation emitted from the AGN central engine: (i) outflows driven from the innermost part of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Daniel Proga , Ryuichi Kurosawa

Changing-look active galactic nuclei (CLAGNs) are known to change their spectral type between 1 and 2 (changing-state) or change their absorption between Compton-thick and Compton-thin (changing-obscuration) on timescales of years or less.…

High Energy Astrophysical Phenomena · Physics 2025-01-17 Bing Lyu , Zhen Yan , Xue-bing Wu , Qingwen Wu , Wenfei Yu , Hao Liu

There is an ongoing debate on whether feedback from active galactic nuclei (AGNs) can effectively regulate the star formation activities in their host galaxies. To investigate the feedback effect of AGN-driven outflows, we perform…

In this paper, standard accretion disk models of AGNs are tested using light curves of 26 objects well observed for reverberation mapping. Time scales of variations are estimated by the most common definition of the variability time scale…

Astrophysics · Physics 2014-01-10 H. T. Liu , J. M. Bai , X. H. Zhao , L. Ma

Galaxy-wide outflows driven by active galactic nuclei (AGN) are an important ingredient in galaxy evolution. Analytical calculations suggest that such outflows have significant inertia and can persist long after the AGN itself fades away.…

Astrophysics of Galaxies · Physics 2023-06-14 Kastytis Zubovas , Gediminas Maskeliūnas

We perform two-dimensional hydrodynamical simulations of slowly rotating accretion flows in the region of $ 0.01-7\, \mathrm{pc} $ around a supermassive black holes with $ M_\mathrm{BH} = 10^{8} M_{\odot} $. The accretion flow is irradiated…

High Energy Astrophysical Phenomena · Physics 2019-10-23 Amin Mosallanezhad , Feng Yuan , Jeremiah P. Ostriker , Fatemeh Zahra Zeraatgari , De-Fu Bu

The first VLBI images of water maser emission in the Circinus Galaxy AGN show both a warped, edge-on accretion disk and an outflow 0.1 to 1 pc from the central engine. The inferred central mass is 1.3 million suns, while the disk mass may…

The existence of outflow in accretion flows is confirmed by observations and magnetohydrodynamics (MHD) simulations. In this paper, we study outflows of accretion flows in the presence of resistivity and toroidal magnetic field. The…

High Energy Astrophysical Phenomena · Physics 2012-05-11 Kazem Faghei , Azam Mollatayefeh

Warped accretion discs in Active Galactic Nuclei (AGN) exert a torque on the black hole that tends to align the rotation axis with the angular momentum of the outer disc. We compute the magnitude of this torque by solving numerically for…

Astrophysics · Physics 2009-10-31 Priyamvada Natarajan , Philip J. Armitage

We explore the origin of fast molecular outflows that have been observed in Active Galactic Nuclei (AGN). Previous numerical studies have shown that it is difficult to create such an outflow by accelerating existing molecular clouds in the…

Astrophysics of Galaxies · Physics 2017-12-27 Alexander J. Richings , Claude-Andre Faucher-Giguere

Outflows driven by active galactic nuclei (AGN) are an important channel for accreting supermassive black holes (SMBHs) to interact with their host galaxies and clusters. Properties of the outflows are however poorly constrained due to the…

Astrophysics of Galaxies · Physics 2022-01-05 Yu Qiu , Brian R. McNamara , Tamara Bogdanovic , Kohei Inayoshi , Luis C. Ho

Active galactic nuclei (AGN) are powered by the accretion of disks of gas onto supermassive black holes (SMBHs). Stars and stellar remnants orbiting the SMBH in the nuclear star cluster (NSC) will interact with the AGN disk. Orbiters…

Astrophysics of Galaxies · Physics 2020-11-02 Gaia Fabj , Syeda S. Nasim , Freddy Caban , K. E. Saavik Ford , Barry McKernan , Jillian M. Bellovary

One way an Active Galactic Nucleus (AGN) influences the evolution of their host galaxy is by generating a large-scale (kpc-scale) outflow. The content, energetics, and impact of such outflows depend on the properties of both the AGN and…

Astrophysics of Galaxies · Physics 2021-08-11 Aisha Al Yazeedi , Ivan Yu. Katkov , Joseph D. Gelfand , Dominika Wylezalek , Nadia L. Zakamska , Weizhe Liu

We present Northern Extended Millimeter Array (NOEMA) observations of the CO (2-1) molecular gas kinematics in the nearby Compton-thick Seyfert 2 galaxy NGC 3079, with an angular resolution of 0.5" ($\sim$40 pc). To interpret the observed…

Cool outflows are now commonly observed in galaxies, but their physical origin and driving mechanism remain unclear. Active galactic nucleus (AGN) feedback can potentially accelerate cool galactic outflows via cosmic rays (CR) and radiation…

High Energy Astrophysical Phenomena · Physics 2022-12-21 W. Ishibashi , A. C. Fabian