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Recent observations have revealed an interesting active galactic nuclei (AGN) subclass that shows strong activity at large scales ($\sim1$ kpc) but weaker at small scales ($<10$ pc), suggesting a strong change in the mass accretion rate of…

Astrophysics of Galaxies · Physics 2022-10-26 J. Pflugradt , K. Ichikawa , M. Akiyama , M. Kokubo , B. Vijarnwannaluk , H. Noda , X. Chen

The impact of Active Galactic Nuclei (AGN) on star formation has implications for our understanding of the relationships between supermassive black holes and their galaxies, as well as for the growth of galaxies over the history of the…

Astrophysics of Galaxies · Physics 2019-04-24 David J. Rosario , Aditya Togi , Leonard Burtscher , Ric Davies , Taro Shimizu , Dieter Lutz

Context: The dusty nuclear regions of luminous infra-red galaxies (LIRGs) are heated by either an intense burst of massive star formation, an active galactic nucleus (AGN), or a combination of both. Disentangling the contribution of each of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Miguel A. Perez-Torres , Antxon Alberdi , Cristina Romero-Canizales , Marco Bondi

The unified model of active galactic nuclei (AGN) claims that the properties of AGN depend on the viewing angle of the observer with respect to a toroidal distribution of dust surrounding the nucleus. Both the mid-infrared (MIR) attenuation…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 O. Gonzalez-Martin , J. M. Rodriguez-Espinosa , T. Diaz-Santos , C. Packham , A. Alonso-Herrero , P. Esquej , C. Ramos Almeida , R. Mason , C. Telesco

We present Australia Compact Telescope Array (ATCA) 21-cm observations of the nearby low-excitation radio galaxy (LERG) NGC 3100. This is the brightest galaxy of a loose group and hosts a young ($\sim 2$ Myr) radio source. The ATCA…

Astrophysics of Galaxies · Physics 2023-07-05 F. M. Maccagni , I. Ruffa , A. Loni , I. Prandoni , R. Ragusa , D. Kleiner , P. Serra , E. Iodice , M. Spavone

Observations of the Seyfert 2 and starburst galaxy NGC 7130 with the Chandra X-ray Observatory illustrate that both of these phenomena contribute significantly to the galaxy's detectable X-ray emission. The active galactic nucleus (AGN) is…

Astrophysics · Physics 2014-10-13 N. A. Levenson , K. A. Weaver , T. M. Heckman , H. Awaki , Y. Terashima

We present the results of the optical identifications of a set of X-ray sources from the all-sky surveys of INTEGRAL and SWIFT observatories. Optical data were obtained with Russian-Turkish 1.5-m Telescope (RTT150). Nine X-ray sources were…

We are conducting a search for supermassive black holes (SMBHs) with masses below 10^7 M_sun by looking for signs of extremely low-level nuclear activity in nearby galaxies that are not known to be AGNs. Our survey has the following…

Astrophysics · Physics 2009-11-13 Himel Ghosh , Smita Mathur , Fabrizio Fiore , Laura Ferrarese

NGC1808 is a nearby spiral galaxy that harbours an active central region with an extent of 20 arcsec (i.e. 1 kpc). Previous X-ray and optical/NIR observations have provided convincing evidence for the existence of a starburst and an AGN. We…

Astrophysics · Physics 2007-05-23 E. Jimenez-Bailon , M. Santos-Lleo , M. Dahlem , M. Ehle , M. Guainazzi , J. M. Mas Hess

NGC 3147 has been considered the best case of a true type 2 AGN: an unobscured AGN, based on the unabsorbed compact X-ray continuum, which lacks a broad line region (BLR). However, the very low luminosity of NGC 3147 implies a compact BLR,…

UM 625, previously identified as a narrow-line active galactic nucleus (AGN), actually exhibits broad \ha\ and \hb\ lines whose width and luminosity indicate a low black hole mass of $1.6 \times 10^6$ \msun. We present a detailed…

Astrophysics of Galaxies · Physics 2015-06-15 Ning Jiang , Luis C. Ho , Xiao-bo Dong , Huan Yang , Junxian Wang

We present X-ray observations of the ultraluminous infrared galaxy, UGC 5101, thought to contain a buried active galactic nucleus (AGN) based on observations in other wavebands. We detected an absorbed hard component at >3 keV, as well as…

Astrophysics · Physics 2009-11-10 Masatoshi Imanishi , Yuichi Terashima , Naohisa Anabuki , Takao Nakagawa

We have conducted a high-resolution spectroscopic study using Spitzer of 18 bulgeless (Sd/Sdm) galaxies that show no definitive signatures of nuclear activity in their optical spectra. This is the first systematic mid-IR search for weak or…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 S. Satyapal , T. Boeker , W. Mcalpine , M. Gliozzi , N. P. Abel , T. Heckman

X-ray emission detection in a galaxy is one of the efficient tools for selecting Active Galactic Nuclei (AGNs). However, many X-ray-selected AGNs are not easily selected as AGNs by their optical emission. These galaxies, so-called optically…

Astrophysics of Galaxies · Physics 2022-03-31 Itsna K. Fitriana , Takashi Murayama

Motivated by theoretical expectations that Nuclear Star Clusters (NSCs) in galactic centers may provide a favorable environment for super-massive black holes to form and/or efficiently grow, we set out to measure the fraction of nearby…

High Energy Astrophysical Phenomena · Physics 2017-05-31 Adi Foord , Elena Gallo , Edmund Hodges-Kluck , Brendan P. Miller , Vivienne F. Baldassare , Kayhan Gultekin , Oleg Y. Gnedin

We report the results of a pilot study that searched for dual active galactic nuclei (AGN) in local ($z<$0.25) galaxies hosting double-peaked narrow emission lines in their optical spectra. We present high-resolution $L-$band (1.5 GHz or 18…

Highly obscured active galactic nuclei (AGN) are common in nearby galaxies, but are difficult to observe beyond the local Universe, where they are expected to significantly contribute to the black hole accretion rate density. Furthermore,…

Obscured active galactic nuclei (AGNs) are thought to be very common in the Universe. Observations and surveys have shown that the number of sources increases for near galaxies and at the low-luminosity regime (the so-called LLAGNs).…

We present near-infrared and millimeter investigations of the nucleus of the infrared luminous galaxy NGC 4418, which previous observations suggest possesses a powerful buried AGN. We found the following main results: (1) The infrared…

Astrophysics · Physics 2009-11-10 Masatoshi Imanishi , Kouichiro Nakanishi , Nario Kuno , Kotaro Kohno

Galaxies which strongly deviate from the radio-far IR correlation are of great importance for studies of galaxy evolution as they may be tracing early, short-lived stages of starbursts and active galactic nuclei (AGNs). The most extreme…

Astrophysics of Galaxies · Physics 2016-10-26 F. Costagliola , R. Herrero-Illana , A. Lohfink , M. Pérez-Torres , S. Aalto , S. Muller , A. Alberdi