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We present a long temporal baseline variability survey in the Frontier Field MACSJ1149. In this study, we identify active galactic nuclei (AGNs) and other transient sources via their variability using over a decade of Hubble Space Telescope…

Astrophysics of Galaxies · Physics 2020-05-27 John Della Costa , Vicki L. Sarajedini , Louis-Gregory Strolger

The rare case of changing-look (CL) AGNs, with the appearance or disappearance of broad Balmer emission lines within a few years, challenges our understanding of the AGN unified model. We present a sample of 21 new CL AGNs at $0.08<z<0.58$,…

Over the next ten years, the Vera C.\ Rubin Observatory (VRO) will observe $\sim$10 million active galactic nuclei (AGN) with a regular and high cadence. During this time, the intensities of most of these AGN will fluctuate stochastically.…

Astrophysics of Galaxies · Physics 2022-12-20 Cyril Creque-Sarbinowski , Marc Kamionkowski , Bei Zhou

Periodic variability in active galactic nuclei (AGN) light curves has been proposed as a signature of close supermassive black hole (SMBH) binaries. Recently, 181 candidate SMBH binaries were identified in Gaia DR3 based on apparently…

Astrophysics of Galaxies · Physics 2026-01-28 Kareem El-Badry , David W. Hogg , Hans-Walter Rix

Here we investigate light curves of the continuum and emission lines of five type 1 active galactic nuclei (AGN) from our monitoring campaign, to test time-evolution of their time delays.Using both modeled and observed AGN light curves we…

We study variability of active galactic nuclei (AGNs) by using the deep optical multiband photometry data obtained from the Hyper Suprime-Cam Subaru Strategic Program (HSC SSP) survey in the COSMOS field. The images analyzed here were taken…

Astrophysics of Galaxies · Physics 2020-05-13 Yuki Kimura , Toru Yamada , Mitsuru Kokubo , Naoki Yasuda , Tomoki Morokuma , Tohru Nagao , Yoshiki Matsuoka

Active galactic nuclei (AGN) are some of the brightest and most variable objects in the Universe. Those with relativistic jets observed at small viewing angles are blazars. Due to Doppler boosting, blazars exhibit extreme stochastic…

Continuum and emission-line variability of active galactic nuclei provides a powerful probe of microarcsecond scale structures in the central regions of these sources. In this contribution, we review basic concepts and methodologies used in…

Astrophysics · Physics 2016-11-03 Bradley M. Peterson

Radiation from the blazar class of of active galactic nuclei (AGN) exhibits fast time variability which is usually ascribed to instabilities in the emission region near the central supermassive black hole. The variability time scale is…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Kenji Nakagawa , Masaki Mori

Active Galactic Nucleus (AGN) variability can be used to study the physics of the region in the vicinity of the central black hole. In this paper, we investigated intra-night optical variability of AGN in the COSMOS field in order to…

Astrophysics of Galaxies · Physics 2018-09-12 Joonho Kim , Marios Karouzos , Myungshin Im , Changsu Choi , Dohyeong Kim , Hyunsung D. Jun , Joon Hyeop Lee , Mar Mezcua

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

Active Galactic Nuclei (AGN) are multiwavelength emitters. To have any hope of understanding them, or even to determine their energy output, we must observe them with many telescopes. I will review what we have learned from broad-band…

Astrophysics · Physics 2007-05-23 Belinda J. Wilkes

Light emission from galaxies exhibit diverse brightness profiles, influenced by factors such as galaxy type, structural features and interactions with other galaxies. Elliptical galaxies feature more uniform light distributions, while…

Astrophysics of Galaxies · Physics 2025-10-20 Euclid Collaboration , G. Stevens , S. Fotopoulou , M. N. Bremer , T. Matamoro Zatarain , K. Jahnke , B. Margalef-Bentabol , M. Huertas-Company , M. J. Smith , M. Walmsley , M. Salvato , M. Mezcua , A. Paulino-Afonso , M. Siudek , M. Talia , F. Ricci , W. Roster , N. Aghanim , B. Altieri , S. Andreon , H. Aussel , C. Baccigalupi , M. Baldi , S. Bardelli , P. Battaglia , A. Biviano , A. Bonchi , E. Branchini , M. Brescia , J. Brinchmann , S. Camera , G. Cañas-Herrera , V. Capobianco , C. Carbone , J. Carretero , M. Castellano , G. Castignani , S. Cavuoti , K. C. Chambers , A. Cimatti , C. Colodro-Conde , G. Congedo , C. J. Conselice , L. Conversi , Y. Copin , A. Costille , F. Courbin , H. M. Courtois , M. Cropper , A. Da Silva , H. Degaudenzi , G. De Lucia , C. Dolding , H. Dole , M. Douspis , F. Dubath , X. Dupac , S. Dusini , S. Escoffier , M. Farina , S. Ferriol , K. George , C. Giocoli , B. R. Granett , A. Grazian , F. Grupp , S. V. H. Haugan , I. M. Hook , F. Hormuth , A. Hornstrup , P. Hudelot , M. Jhabvala , E. Keihänen , S. Kermiche , A. Kiessling , M. Kilbinger , B. Kubik , M. Kümmel , H. Kurki-Suonio , Q. Le Boulc'h , A. M. C. Le Brun , D. Le Mignant , P. B. Lilje , V. Lindholm , I. Lloro , G. Mainetti , D. Maino , E. Maiorano , O. Marggraf , M. Martinelli , N. Martinet , F. Marulli , R. Massey , S. Maurogordato , H. J. McCracken , E. Medinaceli , S. Mei , M. Melchior , M. Meneghetti , E. Merlin , G. Meylan , A. Mora , M. Moresco , L. Moscardini , R. Nakajima , C. Neissner , S. -M. Niemi , C. Padilla , S. Paltani , F. Pasian , K. Pedersen , W. J. Percival , V. Pettorino , G. Polenta , M. Poncet , L. A. Popa , L. Pozzetti , F. Raison , R. Rebolo , A. Renzi , J. Rhodes , G. Riccio , E. Romelli , M. Roncarelli , R. Saglia , A. G. Sánchez , D. Sapone , J. A. Schewtschenko , M. Schirmer , P. Schneider , T. Schrabback , A. Secroun , S. Serrano , P. Simon , C. Sirignano , G. Sirri , J. Skottfelt , L. Stanco , J. Steinwagner , P. Tallada-Crespí , A. N. Taylor , I. Tereno , S. Toft , R. Toledo-Moreo , F. Torradeflot , I. Tutusaus , L. Valenziano , J. Valiviita , T. Vassallo , G. Verdoes Kleijn , A. Veropalumbo , Y. Wang , J. Weller , A. Zacchei , G. Zamorani , F. M. Zerbi , I. A. Zinchenko , E. Zucca , V. Allevato , M. Ballardini , M. Bolzonella , E. Bozzo , C. Burigana , R. Cabanac , A. Cappi , J. A. Escartin Vigo , L. Gabarra , W. G. Hartley , J. Martín-Fleitas , S. Matthew , R. B. Metcalf , A. Pezzotta , M. Pöntinen , I. Risso , V. Scottez , M. Sereno , M. Tenti , M. Wiesmann , Y. Akrami , S. Alvi , I. T. Andika , S. Anselmi , M. Archidiacono , F. Atrio-Barandela , D. Bertacca , M. Bethermin , L. Bisigello , A. Blanchard , L. Blot , S. Borgani , M. L. Brown , S. Bruton , A. Calabro , F. Caro , T. Castro , F. Cogato , S. Davini , G. Desprez , A. Díaz-Sánchez , J. J. Diaz , S. Di Domizio , J. M. Diego , P. -A. Duc , A. Enia , Y. Fang , A. G. Ferrari , A. Finoguenov , A. Fontana , A. Franco , J. García-Bellido , T. Gasparetto , V. Gautard , E. Gaztanaga , F. Giacomini , F. Gianotti , M. Guidi , C. M. Gutierrez , A. Hall , S. Hemmati , H. Hildebrandt , J. Hjorth , J. J. E. Kajava , Y. Kang , V. Kansal , D. Karagiannis , C. C. Kirkpatrick , S. Kruk , L. Legrand , M. Lembo , F. Lepori , G. Leroy , J. Lesgourgues , L. Leuzzi , T. I. Liaudat , J. Macias-Perez , M. Magliocchetti , F. Mannucci , R. Maoli , C. J. A. P. Martins , L. Maurin , M. Miluzio , P. Monaco , G. Morgante , K. Naidoo , A. Navarro-Alsina , F. Passalacqua , K. Paterson , L. Patrizii , A. Pisani , D. Potter , S. Quai , M. Radovich , P. -F. Rocci , G. Rodighiero , S. Sacquegna , M. Sahlén , D. B. Sanders , E. Sarpa , A. Schneider , M. Schultheis , D. Sciotti , E. Sellentin , F. Shankar , L. C. Smith , K. Tanidis , G. Testera , R. Teyssier , S. Tosi , A. Troja , M. Tucci , C. Valieri , D. Vergani , G. Verza , N. A. Walton

We present a study of variability time scales in a large sample of Active Galactic Nuclei at several frequencies between 4.8 and 230 GHz. We investigate the differences of various AGN types and frequencies and correlate the measured time…

Changing-look active galactic nuclei (CLAGNs) show the appearance and disappearance of broad emission lines in their UV/optical spectra on timescales of months to decades. Here, we investigate how CL transitions depend on several AGN…

Astrophysics of Galaxies · Physics 2025-01-08 A. Jana , C. Ricci , M. J. Temple , H. -K. Chang , E. Shablovinskaya , B. Trakhtenbrot , Y. Diaz , D. Ilic , P. Nandi , M. Koss

We examine the continuum variability of active galactic nuclei (AGNs) by analyzing the multi-epoch spectroscopic data from the Sloan Digital Sky Survey. To achieve this, we utilized approximately 2 million spectroscopy pairwise combinations…

Astrophysics of Galaxies · Physics 2025-11-13 Minjin Kim , Suyeon Son , Luis C. Ho

Motivated by upcoming photometric and spectroscopic surveys (Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), Manuakea Spectroscopic Explorer), we design the statistical proxies to measure the cadence effects on active…

We searched the Northern Hemisphere Fields of the GALEX Time-Domain Survey (TDS) for galaxies with UV variability indicative of active galactic nuclei (AGNs). We identified 48 high-probability candidate AGNs from a parent sample of 1819…

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

We use nine years of gamma-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves of more than two thousand active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different…

High Energy Astrophysical Phenomena · Physics 2020-07-01 P. Peñil , A. Domínguez , S. Buson , M. Ajello , J. Otero-Santos , J. A. Barrio , R. Nemmen , S. Cutini , B. Rani , A. Franckowiak , E. Cavazzuti

Emission from active galactic nuclei (AGNs) is known to play an important role in the evolution of many galaxies including luminous and ultraluminous systems (U/LIRGs), as well as merging systems. However, the extent, duration, and exact…