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The maximum number density of Active Galactic Nuclei (AGNs), as deduced from X-ray studies, occurs at z<~1, with lower luminosity objects peaking at smaller redshifts. Optical studies lead to a different evolutionary behaviour, with a…

Astrophysics · Physics 2009-11-13 D. Trevese , F. Vagnetti , S. Puccetti , F. Fiore , M. Tomei , M. A. Bershady

We present a study of Spitzer/IRAC and X-ray active galactic nuclei (AGNs) selection techniques in order to quantify the overlap, uniqueness, contamination, and completeness of each. We investigate how the overlap and possible contamination…

We present the multi-wavelength and environmental properties of 37 variability-selected active galactic nuclei (AGNs), including 30 low luminosity AGNs (LLAGNs), using a high cadence time-domain survey (ASAS-SN) from a spectroscopic sample…

Astrophysics of Galaxies · Physics 2025-01-30 Heechan Yuk , Xinyu Dai , Marko Mićić

We present a highly reliable and efficient mid-infrared colour-based selection technique for luminous active galactic nuclei (AGN) using the Wide-field Infrared Survey Explorer (WISE) survey. Our technique is designed to identify objects…

Astrophysics of Galaxies · Physics 2015-06-18 S. Mateos

In order to understand the interaction between the central black hole and the whole galaxy or their co-evolution history along with cosmic time, a complete census of active galactic nuclei (AGN) is crucial. However, AGNs are often missed in…

We introduce a new infrared diagnostic to separate galaxies on the basis of their dominant infrared emission: stellar or nuclear. The main novelty with respect to existing diagnostics, is the usage of a broad band encompassing at the same…

Astrophysics of Galaxies · Physics 2015-06-22 Dario Fadda , Giulia Rodighiero

Searching for active galactic nuclei (AGN) in dwarf galaxies is important for our understanding of the seed black holes that formed in the early Universe. Here, we test infrared selection methods for AGN activity at low galaxy masses. Our…

Astrophysics of Galaxies · Physics 2016-12-07 Kevin N. Hainline , Amy E. Reines , Jenny E. Greene , Daniel Stern

We perform a systematic X-ray spectroscopic analysis of 57 local ultra/luminous infrared galaxy systems (containing 84 individual galaxies) observed with Nuclear Spectroscopic Telescope Array and/or Swift/BAT. Combining soft X-ray data…

X-rays provide a robust method in identifying AGN. However, in the high-redshift Universe, their space density is relatively low, and, in combination with the small areas covered by X-ray surveys, the selected AGN are poorly sampled. Deep…

Astrophysics of Galaxies · Physics 2025-05-21 E. Pouliasis , A. Ruiz , I. Georgantopoulos , A. Akylas , N. A. Webb , F. J. Carrera , S. Mateos , A. Nebot , M. G. Watson , F. X. Pineau , C. Motch

Variability is a main property of active galactic nuclei (AGN) and it was adopted as a selection criterion using multi epoch surveys conducted for the detection of supernovae (SNe). We have used two SN datasets. First we selected the AXAF…

Astrophysics of Galaxies · Physics 2010-03-03 K. Boutsia , B. Leibundgut , D. Trevese , F. Vagnetti

We analyze the X-ray properties for a sample of 23 high probability AGN candidates with ultraviolet variability identified in Wasleske et al. (2022). Using data from the Chandra X-ray Observatory and the XMM-Newton Observatory, we find…

Astrophysics of Galaxies · Physics 2024-05-31 Erik J. Wasleske , Vivienne F. Baldassare

We investigate the far-infrared (far-IR) incidence of X-ray-selected active galactic nuclei (AGN) and non-AGN galaxies as a function of stellar mass (M$_*$), star formation rate (SFR), and specific black hole accretion rate…

Astrophysics of Galaxies · Physics 2025-08-27 G. Mountrichas , F. J. Carrera , I. Georgantopoulos , S. Mateos , A. Ruiz , A. Corral

We aim to determine the intrinsic far-Infrared (far-IR) emission of X-ray-luminous quasars over cosmic time. Using a 16 deg^2 region of the Stripe 82 field surveyed by XMM-Newton and Herschel Space Observatory, we identify 2905 X-ray…

We employ the Chandra Multiwavelength Project (ChaMP) and the Sloan Digital Sky Survey (SDSS) to study the fraction of X-ray-active galaxies in the field out to z = 0.7. We utilize spectroscopic redshifts from SDSS and ChaMP, as well as…

High Energy Astrophysical Phenomena · Physics 2015-05-18 Daryl Haggard , Paul J. Green , Scott F. Anderson , Anca Constantin , Tom L. Aldcroft , Dong-Woo Kim , Wayne A. Barkhouse

We provide a comprehensive census of the near-Infrared (NIR, 0.8-2.4 $\mu$m) spectroscopic properties of 102 nearby (z < 0.075) active galactic nuclei (AGN), selected in the hard X-ray band (14-195 keV) from the Swift-Burst Alert Telescope…

We present a sample of 10 low-mass active galactic nuclei (AGNs) selected from the 40-month NuSTAR serendipitous survey. The sample is selected to have robust NuSTAR detections at $3 - 24$~keV, to be at $z < 0.3$, and to have optical r-band…

We combine data from two all-sky surveys in order to study the connection between the infrared and hard X-ray (>10keV) properties for local active galactic nuclei (AGN). The Swift/Burst Alert Telescope all-sky survey provides an unbiased,…

Active dwarf galaxies are important because they contribute to the evolution of dwarf galaxies and can reveal their hosted massive black holes. However, the sample size of such sources beyond the local universe is still highly limited. In…

We aim to study the effect of environment on the presence and fuelling of Active Galactic Nuclei (AGN) in massive galaxy clusters. We explore the use of different AGN detection techniques with the goal of selecting AGN across a broad range…

Astrophysics of Galaxies · Physics 2015-06-05 Alison J. Klesman , Vicki L. Sarajedini

The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 M. Young , W. N. Brandt , Y. Q. Xue , M. Paolillo , D. M. Alexander , F. E. Bauer , B. D. Lehmer , B. Luo , O. Shemmer , D. P. Schneider , C. Vignali