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Using a new color-color diagnostic diagram in the mid infrared built from WISE data, the MIRDD, we compare narrow emission-line galaxies (NELGs) that exhibit different activity types (star-forming galaxies, SFGs, and AGNs, i.e.,LINERs, Sy2s…

Astrophysics of Galaxies · Physics 2015-05-27 R. Coziol , J. P. Torres-Papaqui , H. Andernach

This is the first paper in a dedicated series to study the properties of the optically selected BLR-less AGNs (Active Galactic Nuclei with no-hidden central broad emission line regions). We carried out a systematic search for the BLR-less…

Astrophysics of Galaxies · Physics 2015-06-17 Xue Guang Zhang

We analyze the validity of optical diagnostic diagrams relying on emission-lines ratios and in the context of classifying Active Galactic Nuclei (AGNs) according to the cosmic metallicity evolution in the redshift range 0 < z < 11.2. In…

Astrophysics of Galaxies · Physics 2023-11-27 Oli L. Dors , M. V. Cardaci , G. F. Hagele , G. S. Ilha , C. B. Oliveira , R. A. Riffel , R. Riffel , A. C. Krabbe

We present measurements of the dust attenuation of H\alpha-selected emission-line galaxies at z=0.8 from the NewH\alpha\ narrowband survey. The analysis is based on deep follow-up spectroscopy with Magellan/IMACS, which captures the strong…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Ivelina Momcheva , Janice C. Lee , Chun Ly , Samir Salim , Daniel A. Dale , Masami Ouchi , Rose Finn , Yoshiaki Ono

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

The Swift Burst Alert Telescope (BAT) survey of Active Galactic Nuclei (AGN) is providing an unprecedented view of local AGNs (<z> = 0.03) and their host galaxy properties. In this paper, we present an analysis of the optical spectra of a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Lisa M. Winter , Karen T. Lewis , Michael Koss , Sylvain Veilleux , Brian Keeney , Richard F. Mushotzky

Galaxy mergers play an important role in the growth of galaxies and their supermassive black holes. Simulations suggest that tidal interactions could enhance black hole accretion, which can be tested by the fraction of binary active…

Astrophysics of Galaxies · Physics 2015-06-23 Hai Fu , A. D. Myers , S. G. Djorgovski , Lin Yan , J. M. Wrobel , A. Stockton

With the advancement of technology, machine learning-based analytical methods have pervaded nearly every discipline in modern studies. Particularly, a number of methods have been employed to estimate the redshift of gamma-ray loud active…

High Energy Astrophysical Phenomena · Physics 2023-12-13 Sarvesh Gharat , Abhimanyu Borthakur , Gopal Bhatta

Active galactic nuclei (AGN) at the centres of galaxies can cycle between periods of activity and of quiescence. Characterising the duty-cycle of AGN is crucial for understanding their impact on the evolution of the host galaxy. For radio…

AGN feedback is believed to play an important role in shaping a variety of observed galaxy properties, as well as the evolution of their stellar masses and star formation rates. In particular, in the current theoretical paradigm of galaxy…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Fabio Fontanot , Anna Pasquali , Gabriella De Lucia , Frank C. van den Bosch , Rachel S. Somerville , Xi Kang

Nebular emission lines are powerful diagnostics for the physical processes at play in galaxy formation and evolution. Moreover, emission-line galaxies (ELGs) are one of the main targets of current and forthcoming spectroscopic cosmological…

We discuss the very different methods in each wavelength band for selecting and finding Active Galactic Nuclei (AGN). We briefly review the history of the different techniques for finding AGN and compare and contrast the advantages and…

Astrophysics · Physics 2016-01-27 Richard Mushotzky

We present new quantitative classification methods for emission-line galaxies, which are specially designed to be used in deep galaxy redshift surveys. A good segregation between starbursts and active galactic nuclei, i.e. Seyferts 2s and…

Astrophysics · Physics 2015-06-24 Claudia S. Rola , Elena Terlevich , Roberto J. Terlevich

We present the result of a spectroscopic campaign targeting Active Galactic Nucleus (AGN) candidates selected using a novel unsupervised machine-learning (ML) algorithm trained on optical and mid-infrared (mid-IR) photometry. AGN candidates…

Astrophysics of Galaxies · Physics 2024-02-09 Raphael E. Hviding , Kevin N. Hainline , Andy D. Goulding , Jenny E. Greene

Double-peaked [O III]5007, profiles in active galactic nuclei (AGNs) may provide evidence for the existence of dual AGNs, but a good diagnostic for selecting them is currently lacking. Starting from $\sim$ 7000 active galaxies in SDSS DR7,…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-20 J. -M Wang , Y. -M. Chen , C. Hu , W. -M. Mao , S. Zhang , W. -H. Bian

We present a study of the active galactic nucleus (AGN) activity in the local Universe (z < 0.33) and its correlation with the host galaxy properties, derived from a Sloan Digital Sky Survey (SDSS DR8) sample with spectroscopic…

Using SDSS spectra, we applied an automatic method to search for outflows (OFs) in three large samples of narrow-line AGN at low redshifts (z < 0.4), separated in three spectral activity classes: radio-loud RG, 15,793, radio-quiet, Sy2,…

Molecular line ratios, such as HCN(1-0)/HCO$^+$(1-0) and HCN(4-3)/CS(7-6), are routinely used to identify active galactic nuclei (AGN) activity in galaxies. Such ratios are, however, hard to interpret as they are highly dependent on the…

Astrophysics of Galaxies · Physics 2022-11-23 J. Butterworth , J. Holdship , S. Viti , S. García-Burillo

This work presents the properties of 42 objects in the group of the most luminous, highest star formation rate LINERs at z = 0.04 - 0.11. We obtained long-slit spectroscopy of the nuclear regions for all sources, and FIR data (Herschel and…

Astrophysics of Galaxies · Physics 2016-08-31 Mirjana Pović , Isabel Márquez , Hagai Netzer , Josefa Masegosa , Raanan Nordon , Enrique Pérez , William Schoenell

We describe an algorithm to decompose deep images of Active Galactic Nuclei into host galaxy and nuclear components. Currently supported are three galaxy models: A de-Vaucouleurs spheroidal, an exponential disc, and a two-component…

Astrophysics · Physics 2009-11-10 B. Kuhlbrodt , L. Wisotzki , K. Jahnke