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Previously unremarkable, the extragalactic radio source GB 1310+487 showed a gamma-ray flare on 2009 November 18, reaching a daily flux of ~10^-6 photons/cm^2/s at energies E>100 MeV and becoming one of the brightest GeV sources for about…

We report on the finding of a newborn AGN, i.e. current AGN activity in a galaxy previously classified as non-active, and characterize its evolution. Black hole ignition event candidates were selected from a parent sample of spectrally…

SAGE1C\,J053634.78$-$722658.5 is a galaxy at redshift $z=0.14$, discovered behind the Large Magellanic Cloud in the {\it Spitzer} Space Telescope "Surveying the Agents of Galaxy Evolution" Spectroscopy survey (SAGE-Spec). It has very strong…

Astrophysics of Galaxies · Physics 2015-09-23 Jacco Th. van Loon , Anne E. Sansom

We use a sample of over 5000 active galactic nuclei (AGN) with extended morphologies at z<0.8 from the Sloan Digital Sky Survey (SDSS) to study the ensemble optical variability as a function of rest-frame time lag and AGN luminosity with…

Astrophysics of Galaxies · Physics 2014-10-01 Unai Gallastegui-Aizpun , Vicki L. Sarajedini

We analyse the stellar populations in the host galaxies of 53 X-ray selected optically dull active galactic nuclei (AGN) at 0.34<z<1.07 with ultra-deep (m=26.5) optical medium-band (R~50) photometry from the Survey for High-z Absorption Red…

In deep X-ray surveys, active galactic nuclei (AGNs) with a broad range of luminosities have been identified. However, cosmologically distant low-luminosity AGN (LLAGN, $L_{\mathrm{X}} \lesssim 10^{42}$ erg s$^{-1}$) identification still…

We have employed a reliable technique of classification of Active Galactic Nuclei (AGN) based on the fit of well-sampled spectral energy distributions (SEDs) with a complete set of AGN and starburst galaxy templates. We have compiled…

In 2019, Sgr A* - the supermassive black hole in the Galactic Center - underwent unprecedented flaring activity in the near infrared (NIR), brightening by up to a factor of 100 compared to quiescent values. Here we report ALMA observations…

Astrophysics of Galaxies · Physics 2021-10-13 Lena Murchikova , Gunther Witzel

We investigate the mid-infrared properties of the largest (42 objects) sample of radio-loud narrow-line Seyfert 1 (RL NLS1) collected to date, using data from the Wide-field Infrared Survey Explorer (WISE). We analyse the mid-IR colours of…

Astrophysics of Galaxies · Physics 2015-04-28 A. Caccianiga , S. Anton , L. Ballo , L. Foschini , T. Maccacaro , R. Della Ceca , P. Severgnini , M. J. Marcha , S. Mateos , E. Sani

Radio-loud active galactic nuclei (AGN) are among the most luminous objects in the Universe, emitting radiation from low-energy radio waves to high energy $\gamma$-rays. They are well known to exhibit flux variations at nearly all…

Astrophysics of Galaxies · Physics 2026-03-19 M. Reshma , C. S. Stalin , Amit Kumar Mandal , S. B. Gudennavar , Senorita Benedict , Prajwel Joseph

We present a study of galaxies showing mid-infrared variability in the deepest Spitzer/MIPS 24 $\mu$m surveys in the GOODS-South field. We divide the dataset in epochs and subepochs to study the long-term (months-years) and the short-term…

We present infrared K'- (2.1 micron) and L'-band (3.8 micron) high-spatial-resolution (<0.3") imaging observations of 17 nearby (z < 0.17) ultraluminous infrared galaxies (ULIRGs) assisted with the adaptive optics of the Subaru Telescope.…

Astrophysics of Galaxies · Physics 2020-03-25 Masatoshi Imanishi , Taiki Kawamuro , Satoshi Kikuta , Suzuka Nakano , Yuriko Saito

Four ultra-luminous infrared galaxies (ULIRGs) observed with JWST/NIRcam in the Cosmos Evolution Early Release Science program offer an unbiased preview of the $z\approx2$ ULIRG population. The objects were originally selected at 24 $\mu$m…

In order to find more examples of the elusive high-redshift molecular absorbers, we have embarked on a systematic discovery program for highly obscured, radio-loud "invisible AGN" using the VLA Faint Images of the Radio Sky at Twenty…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 T. Yan , J. T. Stocke , J. Darling , F. Hearty

We report the detection of strong absorption and weak emission features in the 4--27 micron Spitzer-IRS spectrum of the distant ultraluminous infrared galaxy (ULIRG) IRAS F00183--7111 (z=0.327). The absorption features of CO2 and CO gas,…

We present results from Chandra observations of 14 ultraluminous infrared galaxies (ULIRGs; log(L_IR/L_Sun) >= 12) with redshifts between 0.04 and 0.16. The goals of the observations were to investigate any correlation between infrared…

Astrophysics · Physics 2009-11-13 Stacy H. Teng , A. S. Wilson , S. Veilleux , A. J. Young , D. B. Sanders , N. M. Nagar

We present preliminary results on the variability properties of AGN above 20 keV in order to show the potential of the INTEGRAL IBIS/ISGRI and Swift/BAT instruments for hard X-ray timing analysis of AGN. The 15-50 keV light curves of 36 AGN…

High Energy Astrophysical Phenomena · Physics 2010-01-26 S. Soldi , G. Ponti , V. Beckmann , P. Lubinski

The goal of this paper is to investigate the physical nature of galaxies in the redshift range $0.02<z<0.15$ that have strong excess emission at mid-IR wavelengths and to determine whether they host a population of accreting black holes…

Astrophysics of Galaxies · Physics 2017-12-13 Guinevere Kauffmann
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