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The Six-degree Field Galaxy Survey (6dFGS) is a spectroscopic redshift survey of the Southern hemisphere completed in 2006. While it provides 136,304 spectra of mostly low-redshift galaxies, a large and reliable catalogue of Active Galactic…

Astrophysics of Galaxies · Physics 2024-10-14 Wei Jeat Hon , Rachel Webster , Christian Wolf

The Sloan Lens ACS (SLACS) Survey is an efficient Hubble Space Telescope Snapshot imaging survey for new galaxy-scale strong gravitational lenses. The targeted lens candidates are selected spectroscopically from within the Sloan Digital Sky…

We searched in the public archive of the Chandra X-ray Observatory as of March 2016 and assembled a sample of 719 galaxies within 50 Mpc with ACIS observations available. By cross-correlation with the optical or near-infrared nuclei of…

Astrophysics of Galaxies · Physics 2017-02-08 Rui She , Luis C. Ho , Hua Feng

Tidal features are a key observable prediction of the hierarchical model of galaxy formation and contain a wealth of information about the properties and history of a galaxy. Modern wide-field surveys such as LSST and Euclid will…

Astrophysics of Galaxies · Physics 2024-09-23 Alexander J. Gordon , Annette M. N. Ferguson , Robert G. Mann

We review the coronal visible and infrared lines, collecting previous observations, and comparing, whenever available, observed radiances with those predicted by various models: the quiet Sun, a moderately active Sun, and an active region…

Solar and Stellar Astrophysics · Physics 2018-01-10 Giulio Del Zanna , Edward E. DeLuca

While emission-line flux ratio diagnostics are the most common technique for identifying active galactic nuclei (AGNs) in optical spectra, applying this approach to single fiber spectra of galaxies can omit entire subpopulations of AGNs.…

To establish the connection between galaxies and UV-detected absorption systems in the local universe, a deep ($g\leq20$) and wide ($\sim20^{\prime}$ radius) galaxy redshift survey is presented around 47 sight lines to UV-bright AGN…

We investigate the clustering properties of ~1550 broad-line active galactic nuclei (AGNs) at <z>=0.25 detected in the ROSAT All-Sky Survey (RASS) through their measured cross-correlation function with ~46,000 Luminous Red Galaxies (LRGs)…

Cosmology and Nongalactic Astrophysics · Physics 2010-03-26 Mirko Krumpe , Takamitsu Miyaji , Alison L. Coil

Variability has proven to be a powerful tool to detect active galactic nuclei (AGN) in multi-epoch surveys. The new-generation facilities expected to become operational in the next few years will mark a new era in time-domain astronomy and…

Under the unified model for active galactic nuclei (AGNs), narrow-line (Type 2) AGNs are, in fact, broad-line (Type 1) AGNs but each with a heavily obscured accretion disk. We would therefore expect the optical continuum emission from Type…

We have obtained Keck NIR spectroscopy of a sample of nine M$_\star$ $<$ 10$^{10}$ M$_\odot$ dwarf galaxies to confirm AGN activity and the presence of galaxy-wide, AGN-driven outflows through coronal line (CL) emission. We find strong CL…

Astrophysics of Galaxies · Physics 2021-04-28 Thomas Bohn , Gabriela Canalizo , Sylvain Veilleux , Weizhe Liu

We use the W_Ha versus [NII]/Ha (WHAN) diagram to provide a comprehensive emission-line classification of SDSS galaxies. This classification is able to cope with the large population of weak line galaxies that do not appear in traditional…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-15 R. Cid Fernandes , G. Stasinska , A. Mateus , N. Vale Asari

We have constructed a catalog of active galactic nuclei (AGNs) with $z < 0.13$, based on optical spectroscopy, from the parent sample of galaxies in the 6dF galaxy survey (Final Release of 6dFGS), a census of the Southern hemisphere. This…

Astrophysics of Galaxies · Physics 2022-02-02 Yan-Ping Chen , Ingyin Zaw , Glennys R Farrar , Sana Elgamal

Previous work utilising NASA's High-resolution Coronal Imager (Hi-C 2.1) 17.2 nm observations revealed that, even at the increased spatial scales available in the data-set, there may be evidence for coronal structures that are still not…

Solar and Stellar Astrophysics · Physics 2020-10-21 Thomas Williams , Robert W. Walsh , Hardi Peter , Amy R. Winebarger

Forbidden coronal lines has traditionally called the attention due to the high-energy photons required for their production (IP $>$100~eV, where IP is the ionisation potential of the transitions that originate the line). As such, they are…

Astrophysics of Galaxies · Physics 2025-02-11 Alberto Rodriguez-Ardila , Fernando Cerqueira-Campos

(Abridged) Many classes of active galactic nuclei (AGN) have been defined entirely throughout optical wavelengths while the X-ray spectra have been very useful to investigate their inner regions. However, optical and X-ray results show many…

To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma Supercluster whose density spans 2 orders of magnitude from the sparse…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 Giuseppe Gavazzi , Giulia Savorgnan , Mattia Fumagalli

Deep extragalactic X-ray surveys, such as the Chandra COSMOS-Legacy field (CCLS), are prone to be biased against active galactic nuclei (AGN) with high column densities due to their lower count rates at a given luminosity. To quantify this…

We present a large sample of infrared-luminous candidate active galactic nuclei (AGNs) that lack X-ray detections in Chandra, XMM-Newton, and NuSTAR fields. We selected all optically detected SDSS sources with redshift measurements,…

We investigated by means of MUSE/VLT observations the true size of the coronal line region (CLR) in a local sample of nine active galactic nuclei known for displaying prominent coronal emission. Our analysis show that the CLR is extended…

Astrophysics of Galaxies · Physics 2025-03-14 A. Rodríguez-Ardila , M. A. Fonseca-Faria , L. G. Dahmer-Hahn , A. Prieto , R. Riffel , R. A. Riffel