Related papers: M87: A Misaligned BL LAC?

The strong flaring activity of M87 in early 2008 as observed by the MAGIC telescope

M87 is the first known radio galaxy to emit very high energy (VHE) gamma-rays. During a monitoring program of M87, a rapid flare in VHE gamma-rays was detected by the MAGIC telescope in early 2008. The flux was found to be variable on a…

Cosmology and Nongalactic Astrophysics · Physics 2019-08-13 D. Tescaro , D. Mazin , R. M. Wagner , K. Berger , N. Galante

Long-term IR Photometry of Seyferts

Long-term (up to 10000d) monitoring has been undertaken for 41 Seyferts in the near-IR (JHKL). All but 2 showed variability, with K ampl in the range <0.1 to > 1.1 mags. The timescale for detectable change is from about one week to a few…

Astrophysics · Physics 2009-11-10 I. S. Glass

Long-term variability of the optical spectra of NGC 4151: I. Light curves and flux correlations

Results of a long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). High quality spectra (S/N>50 in the continuum near Halpha and Hbeta) were obtained in the spectral range…

Astrophysics · Physics 2009-11-13 A. I. Shapovalova , L. C. Popovic , S. Collin , A. N. Burenkov , V. H. Chavushyan , N. G. Bochkarev , E. Benítez , D. Dultzin-Hacyan , A. Kovacevic , N. Borisov , L. Carrasco , J. Leon-Tavares , A. Mercado , J. R. Valdes , V. V. Vlasuyk , V. E. Zhdanova

Detection of very high-energy gamma-ray emission from the radio galaxy M87 with LHAASO

The nearby radio galaxy M87 is a very-high-energy (VHE) gamma-ray emitter established by observations with ground-based gamma-ray detectors. Here we report the long-term monitoring of M87 from 2021 to 2024 with Large High Altitude Air…

High Energy Astrophysical Phenomena · Physics 2025-12-29 Zhen Cao , F. Aharonian , Axikegu , Y. X. Bai , Y. W. Bao , D. Bastieri , X. J. Bi , Y. J. Bi , W. Bian , A. V. Bukevich , Q. Cao , W. Y. Cao , Zhe Cao , J. Chang , J. F. Chang , A. M. Chen , E. S. Chen , H. X. Chen , Liang Chen , Lin Chen , Long Chen , M. J. Chen , M. L. Chen , Q. H. Chen , S. Chen , S. H. Chen , S. Z. Chen , T. L. Chen , Y. Chen , N. Cheng , Y. D. Cheng , M. C. Chu , M. Y. Cui , S. W. Cui , X. H. Cui , Y. D. Cui , B. Z. Dai , H. L. Dai , Z. G. Dai , Danzengluobu , X. Q. Dong , K. K. Duan , J. H. Fan , Y. Z. Fan , J. Fang , J. H. Fang , K. Fang , C. F. Feng , H. Feng , L. Feng , S. H. Feng , X. T. Feng , Y. Feng , Y. L. Feng , S. Gabici , B. Gao , C. D. Gao , Q. Gao , W. Gao , W. K. Gao , M. M. Ge , T. T. Ge , L. S. Geng , G. Giacinti , G. H. Gong , Q. B. Gou , M. H. Gu , F. L. Guo , J. Guo , X. L. Guo , Y. Q. Guo , Y. Y. Guo , Y. A. Han , O. A. Hannuksela , M. Hasan , H. H. He , H. N. He , J. Y. He , Y. He , Y. K. Hor , B. W. Hou , C. Hou , X. Hou , H. B. Hu , Q. Hu , S. C. Hu , C. Huang , D. H. Huang , T. Q. Huang , W. J. Huang , X. T. Huang , X. Y. Huang , Y. Huang , Y. Y. Huang , X. L. Ji , H. Y. Jia , K. Jia , H. B. Jiang , K. Jiang , X. W. Jiang , Z. J. Jiang , M. Jin , M. M. Kang , I. Karpikov , D. Khangulyan , D. Kuleshov , K. Kurinov , B. B. Li , C. M. Li , Cheng Li , Cong Li , D. Li , F. Li , H. B. Li , H. C. Li , Jian Li , Jie Li , K. Li , S. D. Li , W. L. Li , W. L. Li , X. R. Li , Xin Li , Y. Z. Li , Zhe Li , Zhuo Li , E. W. Liang , Y. F. Liang , S. J. Lin , B. Liu , C. Liu , D. Liu , D. B. Liu , H. Liu , H. D. Liu , J. Liu , J. L. Liu , M. Y. Liu , R. Y. Liu , S. M. Liu , W. Liu , Y. Liu , Y. N. Liu , Q. Luo , Y. Luo , H. K. Lv , B. Q. Ma , L. L. Ma , X. H. Ma , J. R. Mao , Z. Min , W. Mitthumsiri , H. J. Mu , Y. C. Nan , A. Neronov , K. C. Y. Ng , L. J. Ou , P. Pattarakijwanich , Z. Y. Pei , J. C. Qi , M. Y. Qi , B. Q. Qiao , J. J. Qin , A. Raza , D. Ruffolo , A. Sáiz , M. Saeed , D. Semikoz , L. Shao , O. Shchegolev , X. D. Sheng , F. W. Shu , H. C. Song , Yu. V. Stenkin , V. Stepanov , Y. Su , D. X. Sun , Q. N. Sun , X. N. Sun , Z. B. Sun , J. Takata , P. H. T. Tam , Q. W. Tang , R. Tang , Z. B. Tang , W. W. Tian , L. H. Wan , C. Wang , C. B. Wang , G. W. Wang , H. G. Wang , H. H. Wang , J. C. Wang , Kai Wang , Kai Wang , L. P. Wang , L. Y. Wang , P. H. Wang , R. Wang , W. Wang , X. G. Wang , X. Y. Wang , Y. Wang , Y. D. Wang , Y. J. Wang , Z. H. Wang , Z. X. Wang , Zhen Wang , Zheng Wang , D. M. Wei , J. J. Wei , Y. J. Wei , T. Wen , C. Y. Wu , H. R. Wu , Q. W. Wu , S. Wu , X. F. Wu , Y. S. Wu , S. Q. Xi , J. Xia , G. M. Xiang , D. X. Xiao , G. Xiao , Y. L. Xin , Y. Xing , D. R. Xiong , Z. Xiong , D. L. Xu , R. F. Xu , R. X. Xu , W. L. Xu , L. Xue , D. H. Yan , J. Z. Yan , T. Yan , C. W. Yang , C. Y. Yang , F. Yang , F. F. Yang , L. L. Yang , M. J. Yang , R. Z. Yang , W. X. Yang , Y. H. Yao , Z. G. Yao , L. Q. Yin , N. Yin , X. H. You , Z. Y. You , Y. H. Yu , Q. Yuan , H. Yue , H. D. Zeng , T. X. Zeng , W. Zeng , M. Zha , B. B. Zhang , F. Zhang , H. Zhang , H. M. Zhang , H. Y. Zhang , J. L. Zhang , Li Zhang , P. F. Zhang , P. P. Zhang , R. Zhang , S. B. Zhang , S. R. Zhang , S. S. Zhang , X. Zhang , X. P. Zhang , Y. F. Zhang , Yi Zhang , Yong Zhang , B. Zhao , J. Zhao , L. Zhao , L. Z. Zhao , S. P. Zhao , X. H. Zhao , F. Zheng , W. J. Zhong , B. Zhou , H. Zhou , J. N. Zhou , M. Zhou , P. Zhou , R. Zhou , X. X. Zhou , X. X. Zhou , B. Y. Zhu , C. G. Zhu , F. R. Zhu , H. Zhu , K. J. Zhu , Y. C. Zou , X. Zuo

Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XVI. A Thirteen-Year Study of Spectral Variability in NGC 5548

We present the final installment of an intensive 13-year study of variations of the optical continuum and broad H-beta emission line in the Seyfert 1 galaxy NGC 5548. The data base consists of 1530 optical continuum measurements and 1248…

Astrophysics · Physics 2009-11-07 B. M. Peterson , the International AGN Watch

M87 at metre wavelengths: the LOFAR picture

M87 is a giant elliptical galaxy located in the centre of the Virgo cluster, which harbours a supermassive black hole of mass 6.4x10^9 M_sun, whose activity is responsible for the extended (80 kpc) radio lobes that surround the galaxy. The…

Astrophysics of Galaxies · Physics 2015-06-11 F. de Gasperin , E. Orru' , M. Murgia , A. Merloni , H. Falcke , R. Beck , R. Beswick , L. Birzan , A. Bonafede , M. Bruggen , G. Brunetti , K. Chyzy , J. Conway , J. H. Croston , T. Ensslin , C. Ferrari , G. Heald , S. Heidenreich , N. Jackson , G. Macario , J. McKean , G. Miley , R. Morganti , A. Offringa , R. Pizzo , D. Rafferty , H. Roettgering , A. Shulevski , M. Steinmetz , C. Tasse , S. van der Tol , W. van Driel , R. J. van Weeren , J. E. van Zwieten , A. Alexov , J. Anderson , A. Asgekar , M. Avruch , M. Bell , M. R. Bell , M. Bentum , G. Bernardi , P. Best , F. Breitling , J. W. Broderick , A. Butcher , B. Ciardi , R. J. Dettmar , J. Eisloeffel , W. Frieswijk , H. Gankema , M. Garrett , M. Gerbers , J. M. Griessmeier , A. W. Gunst , T. E. Hassall , J. Hessels , M. Hoeft , A. Horneffer , A. Karastergiou , J. Koehler , Y. Koopman , G. Kuper , P. Maat , G. Mann , M. Mevius , D. D. Mulcahy , H. Munk , R. Nijboer , M. Kuniyoshi , J. Noordam , H. Paas , M. Pandey , V. N. Pandey , A. Polatidis , W. Reich , A. . P. Schoenmakers , J. Sluman , O. Smirnov , C. Sobey , B. Stappers , J. Swinbank , M. Tagger , Y. Tang , I. van Bemmel , W. van Cappellen , A. P. van Duin , M. van Haarlem , J. van Leeuwen , R. Vermeulen , C. Vocks , S. White , M. Wise , O. Wucknitz , P. Zarka

Optical Monitoring of BL Lacertae Object OJ 287: a 40-Day Period?

We present the results of our optical monitoring of the BL Lacertae object OJ 287 during the first half of 2005. The source did not show large-amplitude variations during this period and was in a relatively quiescent state. A possible…

Astrophysics · Physics 2008-11-26 Jianghua Wu , Xu Zhou , Xuebing Wu , Fukun Liu , Bo Peng , Jun Ma , Zhenyu Wu , Zhaoji Jiang , Jiansheng Chen

The Variability of Seyfert 1.8 and 1.9 Galaxies at 1.6 microns

We present a study of Seyfert 1.5-2.0 galaxies observed at two epochs with the Hubble Space Telescope (HST) at 1.6 microns. We find that unresolved nuclear emission from 9 of 14 nuclei varies at the level of 10-40% on timescales of 0.7-14…

Astrophysics · Physics 2009-10-31 A. C. Quillen , Shanna Shaked , A. Alonso-Herrero , Colleen McDonald , Ariane Lee , M. J. Rieke , G. H. Rieke

VERITAS Observations of day-scale flaring of M87 in 2010 April

VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +- 0.16) X 10^{-11}…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 E. Aliu , T. Arlen , T. Aune , M. Beilicke , W. Benbow , A. Bouvier , S. M. Bradbury , J. H. Buckley , V. Bugaev , K. Byrum , A. Cannon , A. Cesarini , L. Ciupik , E. Collins-Hughes , M. P. Connolly , W. Cui , R. Dickherber , C. Duke , M. Errando , A. Falcone , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , S. Godambe , S. Griffin , J. Grube , R. Guenette , G. Gyuk , D. Hanna , J. Holder , H. Huan , G. Hughes , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , S. LeBohec , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , P. Moriarty , R. Mukherjee , P. D Nunez , R. A. Ong , M. Orr , A. N. Otte , N. Park , J. S. Perkins , A. Pichel , M. Pohl , H. Prokoph , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , J. Ruppel , D. B. Saxon , M. Schroedter , G. H. Sembroski , G. D. Şentürk , C. Skole , D. Staszak , G. Tešić , M. Theiling , S. Thibadeau , K. Tsurusaki , J. Tyler , A. Varlotta , V. V. Vassiliev , S. Vincent , M. Vivier , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , T. Weisgarber , D. A. Williams , B. Zitzer

Ultraviolet HST Observations of the Jet in M87

We present new ultraviolet photometry of the jet in M87 obtained from HST WFPC2 imaging. We combine these ultraviolet data with previously published photometry for the knots of the jet in radio, optical, and X-ray, and fit three theoretical…

Astrophysics · Physics 2009-11-10 C. Z. Waters , S. E. Zepf

Interstellar Scintillation of an Extreme Scintillator: PKS B1144-379

The University of Tasmania Ceduna radio telescope has been used to investigate rapid variability in the radio flux density of the BL Lac object PKS B1144-379 at 6.7 GHz. High-cadence monitoring of this extreme scintillator was carried out…

Astrophysics of Galaxies · Physics 2020-09-03 N. M. M. Said , S. P. Ellingsen , H. E. Bignall , S. Shabala , J. N. McCallum , C. Reynolds

Measuring the Time Variation of the Fine-structure Constant with Quasars Detected by LAMOST

The [O III] $\lambda\lambda\ 4960,5008$ emission lines in the optical spectra of galaxies and quasars have been widely used to investigate the possible variation of the fine-structure constant $\alpha$ over cosmic time. In this work, we…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-08 Jin-Nan Wei , Rui-Jie Chen , Jun-Jie Wei , Martín López-Corredoira , Xue-Feng Wu

Curvature in the very-high energy gamma-ray spectrum of M87

The radio galaxy M87 is a variable very-high energy (VHE) gamma-ray source, exhibiting three major flares reported in 2005, 2008, and 2010. Despite extensive studies, the origin of the VHE gamma-ray emission is yet to be understood. In this…

High Energy Astrophysical Phenomena · Physics 2024-05-16 H. E. S. S. Collaboration , F. Aharonian , F. Ait Benkhali , J. Aschersleben , H. Ashkar , M. Backes , V. Barbosa Martins , R. Batzofin , Y. Becherini , D. Berge , K. Bernlöhr , M. Böttcher , C. Boisson , J. Bolmont , M. de Bony de Lavergne , F. Bradascio , R. Brose , F. Brun , B. Bruno , T. Bulik C. Burger-Scheidlin , T. Bylund , S. Casanova , R. Cecil , J. Celic , M. Cerruti , T. Chand , S. Chandra , A. Chen , J. Chibueze , O. Chibueze , T. Collins , G. Cotter , J. Damascene Mbarubucyeye , A. Djannati-Ataï , J. Djuvsland , A. Dmytriiev , K. Egberts , S. Einecke , S. Fegan , G. Fontaine , S. Funk , S. Gabici , J. F. Glicenstein , J. Glombitza , G. Grolleron , L. Haerer , W. Hofmann , T. L. Holch , M. Holler , D. Horns , M. Jamrozy , F. Jankowsky , V. Joshi , I. Jung-Richardt , E. Kasai , K. Katarzyński , R. Khatoon , B. Khélifi , W. Kluźniak , Nu. Komin , K. Kosack , D. Kostunin , A. Kundu , R. G. Lang , S. Le Stum , F. Leitl , A. Lemière , M. Lemoine-Goumard , J. -P. Lenain , I. Lypova , A. Luashvili , J. Mackey , D. Malyshev , G. Martí-Devesa , R. Marx , A. Mehta , M. Meyer , A. Mitchell , R. Moderski , M. O. Moghadam , L. Mohrmann , A. Montanari , E. Moulin , T. Murach , M. de Naurois , J. Niemiec , S. Ohm , L. Olivera-Nieto , E. de Ona Wilhelmi , S. Panny , M. Panter , R. D. Parsons , U. Pensec , S. Pita , G. Pühlhofer , M. Punch , A. Quirrenbach , M. Regeard , A. Reimer , O. Reimer , H. Ren , B. Reville , F. Rieger , B. Rudak , E. Ruiz-Velasco , V. Sahakian , H. Salzmann , A. Santangelo , M. Sasaki , F. Schüssler , H. M. Schutte , J. N. S. Shapopi , H. Sol , S. Spencer , Ł. Stawarz , R. Steenkamp , S. Steinmassl , C. Steppa , K. Streil , T. Takahashi , T. Tanaka , A. M. Taylor , R. Terrier , M. Tsirou , C. van Eldik , C. Venter , J. Vink , T. Wach , S. J. Wagner , A. Wierzcholska , M. Zacharias , A. A. Zdziarski , A. Zech , P. Zilberman , N. Zywucka

Constraining Active Galactic Nucleus Jets with Spectrum and Core Shift: The Case of M87

We analytically model stationary and axisymmetric active galactic nucleus jets, assuming energy conservation along each magnetic flux tube. Using very-long-baseline interferometry (VLBI) observations and published general relativistic…

High Energy Astrophysical Phenomena · Physics 2025-08-11 Kouichi Hirotani , Hsien Shang , Ruben Krasnopolsky , Satoki Matsushita , Britton Jeter , Keiichi Asada

Observing Supernova 1987A with the Refurbished Hubble Space Telescope

Observations with the Hubble Space Telescope (HST), conducted since 1990, now offer an unprecedented glimpse into fast astrophysical shocks in the young remnant of supernova 1987A. Comparing observations taken in 2010 using the refurbished…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Kevin France , Richard McCray , Kevin Heng , Robert Kirshner , Peter Challis , Patrice Bouchet , Arlin Crotts , Eli Dwek , Claes Fransson , Peter Garnavich , Josefin Larsson , Stephen Lawrence , Peter Lundqvist , Nino Panagia , Chun Pun , Nathan Smith , Jesper Sollerman , George Sonneborn , John Stocke , Lifan Wang , Craig Wheeler

FUSE Spectra of the Black Hole Binary LMC X-3

Far-ultraviolet spectra of LMC X-3 were taken covering photometric phases 0.47 to 0.74 in the 1.7-day orbital period of the black-hole binary (phase zero being superior conjunction of the X-ray source). The continuum is faint and flat, but…

Astrophysics · Physics 2009-11-10 J. B. Hutchings , K. Winter , D. Crampton , A. P. Cowley , P. Schmidtke

Spectral Properties of Bright Fermi-detected Blazars in the Gamma-ray Band

The gamma-ray energy spectra of bright blazars of the LAT Bright AGN Sample (LBAS) are investigated using Fermi-LAT data. Spectral properties (hardness, curvature and variability) established using a data set accumulated over 6 months of…

High Energy Astrophysical Phenomena · Physics 2015-05-18 LAT Collaboration

Gamma-ray and Optical Oscillations of 0716+714, MRK 421, and BL Lac

We examine the 2008-2016 $\gamma$-ray and optical light curves of three bright BL Lac objects, 0716+714, MRK 421, BL Lac, which exhibit large structured variability. We searched for periodicities by using a fully Bayesian approach. For two…

High Energy Astrophysical Phenomena · Physics 2017-04-19 A. Sandrinelli , S. Covino , A. Treves , E. Lindfors , C. M. Raiteri , K. Nilsson , L. O. Takalo , R. Reinthal , A. Berdyugin , V. Fallah Ramazani , V. Kadenius , T. Tuominen , P. Kehusmaa , R. Bachev , A. Strigachev

Detection of Superluminal Motion in the X-Ray Jet of M87

Chandra HRC observations are investigated for evidence of proper motion and brightness changes in the X-ray jet of the nearby radio galaxy M87. Using images spanning 5 yr, proper motion is measured in the X-ray knot HST-1, with a…

High Energy Astrophysical Phenomena · Physics 2019-07-10 Bradford Snios , Paul E. J. Nulsen , Ralph P. Kraft , C. C. Cheung , Eileen T. Meyer , William R. Forman , Christine Jones , Stephen S. Murray

The dynamics of the broad-line region in NGC 3227

Archival Hubble Space Telescope (HST) observations of the Seyfert 1 nucleus of NGC 3227 obtained with the Space Telescope Imaging Spectrograph (STIS) are re-examined in order to constrain a viable photoionization model for the broad-line…

Astrophysics of Galaxies · Physics 2020-10-07 Nick Devereux