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The black-hole/accretion-disk paradigm for active galactic nuclei (AGNs) is now reasonably secure, but there are still important unresolved issues, some of which will require the capabilities of an 8 to 10-m class UV/optical space-based…

Astrophysics · Physics 2007-05-23 Bradley M. Peterson

We study the broad-band spectral energy distribution (SED) of the prototypical low-mass active galactic nucleus (AGN) in NGC 4395. We jointly model the optical through mid-infrared SED with a combination of galaxy and AGN light, and find…

Astrophysics of Galaxies · Physics 2023-07-31 Hector Afonso G. Cruz , Andy D. Goulding , Jenny E. Greene

We analyze observations obtained with the Chandra X-ray Observatory of bright Compton thick active galactic nuclei (AGNs), those with column densities in excess of 1.5 x 10^{24} cm^{-2} along the lines of sight. We therefore view the…

Astrophysics · Physics 2011-07-21 N. A. Levenson , T. M. Heckman , J. H. Krolik , K. A. Weaver , P. T. Zycki

Estimating physical quantities such as the star formation rate, stellar mass and active galactic nucleus (AGN) fraction of galaxies is a key step in understanding galaxy formation and evolution. In order to estimate the uncertainties in the…

Astrophysics of Galaxies · Physics 2025-01-14 Michail Papadopoulos , Vicky Papadopoulou Lesta , Ioannis Michos , Duncan Farrah , Andreas Efstathiou

Distinguishing active galaxies from star-forming galaxies is essential for understanding galaxy evolution. Diagnostic methods like the BPT (Baldwin, Phillips, and Terlevich) diagram use optical emission-line ratios to separate galaxies.…

Astrophysics of Galaxies · Physics 2026-03-26 Farideh Mazoochi , Reihaneh Karimi , Mohammad Hossein Zhoolideh Haghighi , Fatemeh Tabatabaei

We present a large-scale study of the X-ray properties and near-IR-to-radio SEDs of submillimetre galaxies (SMGs) detected at 1.1mm with the AzTEC instrument across a ~1.2 square degree area of the sky. Combining deep 2-4 Ms Chandra data…

Utilizing Chandra X-ray observations in the All-wavelength Extended Groth Strip International Survey (AEGIS) we identify 241 X-ray selected Active Galactic Nuclei (AGNs, L > 10^{42} ergs/s) and study the properties of their host galaxies in…

Radio-emitting active galactic nuclei (AGNs) are common in elliptical galaxies and AGN feedback is one of the possible mechanisms for regulating star formation in massive galaxies. It is unclear if all passive galaxy populations host radio…

Astrophysics of Galaxies · Physics 2025-07-16 Hei Yung Chan , Michael J. I. Brown

We examine the processes triggering star formation and Active Galactic Nucleus (AGN) activity in a sample of 25 low redshift ($z<0.13$) gas-rich galaxy mergers observed at milli-arcsecond resolution with Very Long Baseline Interferometry as…

Astrophysics of Galaxies · Physics 2016-10-12 Stanislav Shabala , Adam Deller , Sugata Kaviraj , Enno Middelberg , Ross Turner , Yuan-Sen Ting , James Allison , Tim Davis

We study the possibility of detecting a signature of particle dark matter in the spectrum of gamma-ray photons from active galactic nuclei (AGNs) resulting from the scattering of high-energy particles in the AGN jet off of dark matter…

High Energy Astrophysical Phenomena · Physics 2010-10-27 Mikhail Gorchtein , Stefano Profumo , Lorenzo Ubaldi

We study the incidence of nuclear obscuration on a complete sample of 1310 AGN selected on the basis of their rest-frame 2-10 keV X-ray flux from the XMM-COSMOS survey, in the redshift range 0.3<z<3.5. We classify the AGN as obscured or…

Context. Active galactic nuclei (AGNs) and star forming galaxies (SFGs) are the primary sources of extragalactic radio sky. But it is difficult to distinguish the radio emission produced by AGNs from that by SFGs, especially when the radio…

Astrophysics of Galaxies · Physics 2025-09-17 Xu-Liang Fan , Jie Li

We separate the extragalactic radio source population above ~50 uJy into active galactic nuclei (AGN) and star-forming sources. The primary method of our approach is to fit the infrared spectral energy distributions (SEDs), constructed…

We present results of recurrence analysis of 46 active galactic nuclei (AGN) using light curves from the 157-month catalog of the Swift Burst Alert Telescope (BAT) in the 14-150 keV band. We generate recurrence plots and compute recurrence…

High Energy Astrophysical Phenomena · Physics 2022-11-28 R. A. Phillipson , M. S. Vogeley , P. T. Boyd

We study the relation of active galactic nuclei (AGNs) to star formation in their host galaxies. Our sample includes 205 Type-1 and 85 Type-2 AGNs, 162 detected with Herschel, from fields surrounding 30 galaxy clusters in the Local Cluster…

Astrophysics of Galaxies · Physics 2015-08-19 Lei Xu , G. H. Rieke , E. Egami , C. P. Haines , M. J. Pereira , G. P. Smith

We describe a complete, flux-density-limited sample of galaxies at redshift $0.8 < z < 1.3$ selected at 16 micron. At the selection wavelength near 8 micron rest, the observed emission comes both from dust heated by intense star formation…

During its first four years of scientific observations, the Fermi Large Area Telescope (Fermi-LAT) detected 3033 $\gamma$-ray sources above a 4$\sigma$ significance level. Although most of the extra-Galactic sources are active galactic…

High Energy Astrophysical Phenomena · Physics 2019-08-15 G. La Mura , G. Chiaro , S. Ciroi , P. Rafanelli , D. Salvetti , M. Berton , V. Cracco

We have carried out extensive and detailed photoionization modeling to successfully constrain the locations of different emission-line galaxies in optical and mid-infrared diagnostic diagrams. Our model grids cover a wide range in parameter…

Astrophysics of Galaxies · Physics 2015-06-22 M. Meléndez , T. M. Heckman , M. Martínez-Paredes , S. B. Kraemer , C. Mendoza

We consider the techniques to distinguish normal star forming (NSF) galaxies and active galactic nuclei (AGN) hosts using optical spectra. The observational data base is a set of 20000 galaxies extracted from the Sloan Digital Sky Survey,…

Astrophysics · Physics 2009-12-15 G. Stasinska , R. Cid Fernandes , A. Mateus , L. Sodre , N. V. Asari

We use machine learning techniques to investigate their performance in classifying active galactic nuclei (AGNs), including X-ray selected AGNs (XAGNs), infrared selected AGNs (IRAGNs), and radio selected AGNs (RAGNs). Using known physical…

Astrophysics of Galaxies · Physics 2021-10-26 Yu-Yen Chang , Bau-Ching Hsieh , Wei-Hao Wang , Yen-Ting Lin , Chen-Fatt Lim , Yoshiki Toba , Yuxing Zhong , Siou-Yu Chang