Related papers: EUCLIA - Exploring the UV/optical continuum lag in…

An Alternative Approach To Measuring Reverberation Lags in Active Galactic Nuclei

Motivated by recent progress in the statistical modeling of quasar variability, we develop a new approach to measuring emission-line reverberation lags to estimate the size of broad-line regions (BLRs) in active galactic nuclei. Assuming…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Ying Zu , C. S. Kochanek , Bradley. M. Peterson

S5 0716+714 is a well-studied BL Lac object in the sky. Verifying the existence of correlations among the flux variations in different bands serves as an important tool to investigate the emission processes. To examine the possible…

High Energy Astrophysical Phenomena · Physics 2015-05-18 Bingkai Zhang , Benzhong Dai , Li Zhang , Jiali Liu , Zhen Cao

New constraints on the continuum-emission mechanism of AGN: Intensive monitoring of NGC 7469 in the X-ray and ultraviolet

We have undertaken near-continuous monitoring of the Seyfert 1 galaxy NGC 7469 in the X-ray with RXTE over a ~30d baseline. The source shows strong variability with a root-mean-square (rms) amplitude of ~16 per cent, and peak-to-peak…

Astrophysics · Physics 2009-10-30 K. Nandra , J. Clavel , R. A. Edelson , I. M. George , M. A. Malkan , R. F. Mushotzky , B. M. Peterson , T. J. Turner

X-ray time lags and nonlinear variability in the ultraluminous X-ray sources NGC 5408 X-1 and NGC 6946 X-1

We present our analysis of the X-ray variability of two ultraluminous X-ray sources (ULXs) based on multiple XMM--Newton observations. We show the linear rms-flux relation is present in eight observations of NGC5408 X-1 and also in three…

High Energy Astrophysical Phenomena · Physics 2015-09-16 L. Hernández-García , S. Vaughan , T. P. Roberts , M. Middleton

We study multi-wavelength variability of a bare Seyfert 1 galaxy Fairall~9 using \swift{} monitoring observations consisting of $165$ usable pointings spanning nearly two years and covering six UV/optical bands and X-rays. Fairall~9 is…

High Energy Astrophysical Phenomena · Physics 2017-01-18 Main Pal , Gulab C. Dewangan , S. D. Connolly , Ranjeev Misra

X-ray/UVOIR Frequency-resolved Time Lag Analysis of Mrk 335 Reveals Accretion Disk Reprocessing

UV and optical continuum reverberation mapping is powerful for probing the accretion disk and inner broad-line region. However, recent reverberation mapping campaigns in the X-ray, UV, and optical have found lags consistently longer than…

High Energy Astrophysical Phenomena · Physics 2025-04-21 Collin Lewin , Erin Kara , Edward M. Cackett , Dan Wilkins , Christos Panagiotou , Javier A. Garcia , Jonathan Gelbord

Space Telescope and Optical Reverberation Mapping Project. IV. Anomalous behavior of the broad ultraviolet emission lines in NGC 5548

During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert~1 galaxy NGC 5548 performed from 2014 February to July, the normally highly correlated far-UV continuum and broad…

Astrophysics of Galaxies · Physics 2016-06-15 M. R. Goad , K. T. Korista , G. De Rosa , G. A. Kriss , R. Edelson , A. J. Barth , G. J. Ferland , C. S. Kochanek , H. Netzer , B. M. Peterson , M. C. Bentz , S. Bisogni , D. M. Crenshaw , K. D. Denney , J. Ely , M. M. Fausnaugh , C. J. Grier , A. Gupta , K. D. Horne , J. Kaastra , A. Pancoast , L. Pei , R. W. Pogge , A. Skielboe , D. Starkey , M. Vestergaard , Y. Zu , M. D. Anderson , P. Arevalo , C. Bazhaw , G. A. Borman , T. A. Boroson , M. C. Bottorff , W. N. Brandt , A. A. Breeveld , B. J. Brewer , E. M. Cackett , M. T. Carini , K. V. Croxall , E. Dalla Bonta , A. de Lorenzo-Caceres , M. Dietrich , N. V. Efimova , P. A. Evans , A. V. Filippenko , K. Flatland , N. Gehrels , S. Geier , G. M. Gelbord , L. Gonzalez , V. Gorjian , D. Grupe , P. B. Hall , S. Hicks , D. Horenstein , T. Hutchison , M. Im , J. J. Jensen , M. D. Joner , J. Jones , S. Kaspi , B. C. Kelly , J. A. Kennea , M. Kim , S. C. Kim , S. A. Klimanov , V. M. Larionov , J. C. Lee , D. C. Leonard , P. Lira , F. MacInnis , E. R. Manne-Nicholas , S. Mathur , I. M. McHardy , C. Montouri , R. Musso , S. V. Nazarov , R. P. Norris , J. A. Nousek , D. N. Okhmat , I. Papadakis , J. R. Parks , J. -U. Pott , S. E. Rafter , H. -W. Rix , D. A. Saylor , J. S. Schimoia , K. Schnulle , S. G. Sergeev , M. Siegel , M. Spencer , H. -I. Sung , K. G. Teems , T. Treu , C. S. Turner , P. Uttley , C. Villforth , Y. Weiss , J. -H. Woo , H. Yan , S. Young , W. -K. Zheng

Space Telescope and Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign and Emission-Line Analysis for NGC 5548

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multi-wavelength reverberation mapping campaign. The campaign spanned six months and achieved an almost daily cadence with…

Astrophysics of Galaxies · Physics 2017-03-22 L. Pei , M. M. Fausnaugh , A. J. Barth , B. M. Peterson , M. C. Bentz , G. De Rosa , K. D. Denney , M. R. Goad , C. S. Kochanek , K. T. Korista , G. A. Kriss , R. W. Pogge , V. N. Bennert , M. Brotherton , K. I. Clubb , E. Dalla Bontà , A. V. Filippenko , J. E. Greene , C. J. Grier , M. Vestergaard , W. Zheng , Scott M. Adams , Thomas G. Beatty , A. Bigley , Jacob E. Brown , Jonathan S. Brown , G. Canalizo , J. M. Comerford , Carl T. Coker , E. M. Corsini , S. Croft , K. V. Croxall , A. J. Deason , Michael Eracleous , O. D. Fox , E. L. Gates , C. B. Henderson , E. Holmbeck , T. W. -S. Holoien , J. J. Jensen , C. A. Johnson , P. L. Kelly , S. Kim , A. King , M. W. Lau , Miao Li , Cassandra Lochhaas , Zhiyuan Ma , E. R. Manne-Nicholas , J. C. Mauerhan , M. A. Malkan , R. McGurk , L. Morelli , Ana Mosquera , Dale Mudd , F. Muller Sanchez , M. L. Nguyen , P. Ochner , B. Ou-Yang , A. Pancoast , Matthew T. Penny , A. Pizzella , Radosław Poleski , Jessie Runnoe , B. Scott , Jaderson S. Schimoia , B. J. Shappee , I. Shivvers , Gregory V. Simonian , A. Siviero , Garrett Somers , Daniel J. Stevens , M. A. Strauss , Jamie Tayar , N. Tejos , T. Treu , J. Van Saders , L. Vican , S. Villanueva , H. Yuk , N. L. Zakamska , W. Zhu , M. D. Anderson , P. Arévalo , C. Bazhaw , S. Bisogni , G. A. Borman , M. C. Bottorff , W. N. Brandt , A. A. Breeveld , E. M. Cackett , M. T. Carini , D. M. Crenshaw , A. De Lorenzo-Cáceres , M. Dietrich , R. Edelson , N. V. Efimova , J. Ely , P. A. Evans , G. J. Ferland , K. Flatland , N. Gehrels , S. Geier , J. M. Gelbord , D. Grupe , A. Gupta , P. B. Hall , S. Hicks , D. Horenstein , Keith Horne , T. Hutchison , M. Im , M. D. Joner , J. Jones , J. Kaastra , S. Kaspi , B. C. Kelly , J. A. Kennea , M. Kim , S. C. Kim , S. A. Klimanov , J. C. Lee , D. C. Leonard , P. Lira , F. MacInnis , S. Mathur , I. M. McHardy , C. Montouri , R. Musso , S. V. Nazarov , H. Netzer , R. P. Norris , J. A. Nousek , D. N. Okhmat , I. Papadakis , J. R. Parks , J. -U. Pott , S. E. Rafter , H. -W. Rix , D. A. Saylor , K. Schnülle , S. G. Sergeev , M. Siegel , A. Skielboe , M. Spencer , D. Starkey , H. -I. Sung , K. G. Teems , C. S. Turner , P. Uttley , C. Villforth , Y. Weiss , J. -H. Woo , H. Yan , S. Young , Y. Zu

Euclid Quick Data Release (Q1). Active galactic nuclei identification using diffusion-based inpainting of Euclid VIS images

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

Contrasting X-ray/UV time-lags in Seyfert 1 galaxies NGC 4593 and NGC 7469 using AstroSat observations

We study accretion disk-corona connection in Seyfert 1 galaxies using simultaneous UV/X-ray observations of NGC 4593 (July 14-18, 2016) and NGC 7469 (October 15-19, 2017) performed with AstroSat. We use the X-ray (0.5-7.0 keV) data acquired…

High Energy Astrophysical Phenomena · Physics 2023-03-29 Kavita Kumari , G. C. Dewangan , I. E. Papadakis , Max W. J. Beard , I. M. McHardy , K. P. Singh , D. Bhattacharya , S. Bhattacharyya , S. Chandra

The X-ray/UV ratio in Active Galactic Nuclei: dispersion and variability

The relation between the $\alpha_{OX}$ index and the optical/UV luminosity ($L_{UV}$), a by product of the X-ray - optical/UV luminosity relation, is affected by a relatively large dispersion, due to variability in the $\alpha_{OX}$ within…

Astrophysics of Galaxies · Physics 2018-11-14 Elia Chiaraluce , Fausto Vagnetti , Francesco Tombesi , Maurizio Paolillo

A new timescale-mass scaling for the optical variation of active galactic nuclei across the intermediate-mass to supermassive scales

Variability of active galactic nuclei (AGNs) has long been servicing as an essential avenue of exploring the accretion physics of black hole (BH). There are two commonly used methods for analyzing AGN variability. First, the AGN…

Astrophysics of Galaxies · Physics 2024-07-04 Zhen-Bo Su , Zhen-Yi Cai , Mouyuan Sun , Hengxiao Guo , Wei-Min Gu , Jun-Xian Wang

X-ray reverberation as an explanation for UV/optical variability in nearby Seyferts

Active galactic nuclei (AGNs) are known to be variable across all wavelengths. Significant observational efforts have been invested in the last decade in studying their ultraviolet (UV) and optical variability. Long and densely sampled,…

High Energy Astrophysical Phenomena · Physics 2024-09-17 M. Papoutsis , I. E. Papadakis , C. Panagiotou , M. Dovčiak , E. Kammoun

Continuum Reverberation Mapping of Mrk 876 Over Three Years With Remote Robotic Observatories

Continuum reverberation mapping probes the sizescale of the optical continuum-emitting region in active galactic nuclei (AGN). Through 3 years of multiwavelength photometric monitoring in the optical with robotic observatories, we perform…

Astrophysics of Galaxies · Physics 2023-07-28 Jake A. Miller , Edward M. Cackett , Michael R. Goad , Keith Horne , Aaron J. Barth , Encarni Romero-Colmenero , Michael Fausnaugh , Jonathan Gelbord , Kirk T. Korista , Hermine Landt , Tommaso Treu , Hartmut Winkler

Study of the Nuclear Activity of the Seyfert Galaxy NGC 7469 over the Period of Observations 2008-2014

We present results of multicolor UBVRI observations of the type 1 Seyfert galaxy (SyG 1) NGC 7469 carried out at the 1.5-meter telescope of the Maidanak Observatory (Uzbekistan) in 2008-2014. Analysis of the light curves indicates the…

High Energy Astrophysical Phenomena · Physics 2017-07-21 L. Ugol'kova , B. Artamonov , E. Shimanovskaya , V. Bruevich , O. Burhonov , Sh. Egamberdiev , N. Metlova

Explaining the UV to X-ray correlation in AGN within the framework of X-ray illumination of accretion discs

It is established that the ultraviolet (UV) and X-ray emissions in active galactic nuclei (AGN) are tightly correlated. This correlation is observed both in low- and high-redshift sources. In particular, observations of large samples of…

High Energy Astrophysical Phenomena · Physics 2025-03-27 E. Kammoun , I. E. Papadakis , M. Dovčiak , E. Lusso , E. Nardini , G. Risaliti

The Case for Standard Irradiated Accretion Disks in Active Galactic Nuclei

We analyze the broadband photometric light curves of Seyfert 1 galaxies from the Sergeev et al. (2005) sample and find that a) perturbations propagating across the continuum emitting region are a general phenomenon securely detected in most…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Doron Chelouche

On the time delay evolution of five Active Galactic Nuclei

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…

Astrophysics of Galaxies · Physics 2016-01-20 Andjelka Kovacevic , Luka C. Popovic , Alla I. Shapovalova , Dragana Ilic , Aleksandr N. Burenkov , Vahram H. Chavushyan

Timescale-dependent X-ray to UV time lags of NGC 4593 using high-intensity XMM-Newton observations with Swift and AstroSat

We present a 140ks observation of NGC 4593 with XMM-Newton providing simultaneous and continuous PN X-ray and OM UV (UVW1 2910\AA) lightcurves which sample short-timescale variations better than previous observations. These observations…

High Energy Astrophysical Phenomena · Physics 2022-11-30 Max W. J. Beard , Ian M. McHardy , Kavita Kumari , Gulab C. Dewangan , Iossif Papadakis , Dipankar Bhattacharya , Kulinder Pal Singh , Daniel Kynoch , Mayukh Pahari

X-ray variability of AGN and correlations with spectral properties

Rapid flux changes in the X-ray emission from active galactic nuclei are commonly observed. The power-density spectra show a pseudo power-law form with a turnover at low frequencies and a high frequency break, similar to galactic black-hole…

Astrophysics · Physics 2009-10-31 K. Nandra