Related papers: J16021+3326: New Multi-Frequency Observations of a…

Connection between Gamma-Ray Variations and Disturbances in the Jets of Blazars

We perform monthly total and polarized intensity imaging of a sample of $\gamma$-ray blazars (33 sources) with the Very Long Baseline Array (VLBA) at 43 GHz with the high resolution of 0.1 milliarcseconds. From Summer 2008 to October 2009…

High Energy Astrophysical Phenomena · Physics 2010-01-14 S. Jorstad , A. Marscher , F. D'Arcangelo , B. Harrison

A VLA monitoring study of JVAS B1422+231: investigation of time delays and detection of extrinsic variability

We present an analysis of two seasons of archival, multi-frequency VLA monitoring of the quad lens system JVAS B1422+231, the 15-GHz data of which have previously been published. The 8.4- and 15-GHz variability curves show significant…

Astrophysics of Galaxies · Physics 2023-03-29 A. D. Biggs

OVRO 40 m Blazar Monitoring Program: Location of the gamma-ray emission region in blazars by the study of correlated variability at radio and gamma-rays

Blazars are powerful, variable emitters from radio to gamma-ray wavelengths. Even though the general picture of synchrotron emission at low energies and inverse Compton at the high energy end is well established, many important aspects of…

High Energy Astrophysical Phenomena · Physics 2019-08-15 W. Max-Moerbeck , J. L. Richards , V. Pavlidou , T. J. Pearson , A. C. S. Readhead , T. Hovatta , O. G. King , R. Reeves

Study for relation between direction of relativistic jet and optical polarization angle with multi-wavelength observation

Blazars are thought to possess a relativistic jet that is pointing toward the direction of the Earth and the elect of relativistic beaming enhances its apparent brightness. They radiate in all wavebands from the radio to the gamma-ray bands…

High Energy Astrophysical Phenomena · Physics 2015-02-11 Ryosuke Itoh , Yasushi FUkazawa , Yasuyuki T. Tanaka , Makoto Uemura , Koji S. Kawabata , Hiroshi Akitaya , Kenji Kawaguchi , Yuka Kanda

Very-high-energy gamma-ray detection and long-term multi-wavelength view of the flaring blazar B2 1811+31

Among the blazars whose emission has been detected up to very-high-energy (VHE; 100 GeV < E < 100 TeV) gamma rays, intermediate synchrotron-peaked BL Lacs (IBLs) are quite rare. The IBL B2 1811+31 (z = 0.117) exhibited intense flaring…

High Energy Astrophysical Phenomena · Physics 2025-05-23 K. Abe , S. Abe , J. Abhir , A. Abhishek , V. A. Acciari , A. Aguasca-Cabot , I. Agudo , T. Aniello , S. Ansoldi , L. A. Antonelli , A. Arbet Engels , C. Arcaro , K. Asano , A. Babic , U. Barres de Almeida , J. A. Barrio , L. Barrios-Jimenez , I. Batkovic , J. Baxter , J. Becerra Gonzalez , W. Bednarek , E. Bernardini , J. Bernete , A. Berti , J. Besenrieder , C. Bigongiari , A. Biland , O. Blanch , G. Bonnoli , Ž. Bošnjak , E. Bronzini , I. Burelli , A. Campoy-Ordaz , A. Carosi , R. Carosi , M. Carretero-Castrillo , A. J. Castro-Tirado , D. Cerasole , G. Ceribella , A. Chilingarian , A. Cifuentes , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , F. D'Ammando , G. D'Amico , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , R. de Menezes , M. Delfino , J. Delgado , C. Delgado Mendez , F. Di Pierro , R. Di Tria , L. Di Venere , A. Dinesh , D. Dominis Prester , A. Donini , D. Dorner , M. Doro , L. Eisenberger , D. Elsaesser , J. Escudero , L. Farina , L. Foffano , L. Font , S. Frose , Y. Fukazawa , R. J. Garcia Lopez , M. Garczarczyk , S. Gasparyan , M. Gaug , J. G. Giesbrecht Paiva , N. Giglietto , F. Giordano , P. Gliwny , T. Gradetzke , R. Grau , D. Green , J. G. Green , P. Gunther , D. Hadasch , A. Hahn , T. Hassan , L. Heckmann , J. Herrera Llorente , D. Hrupec , R. Imazawa , D. Israyelyan , T. Itokawa , I. Jimenez Martinez , J. Jimenez Quiles , J. Jormanainen , S. Kankkunen , T. Kayanoki , D. Kerszberg , M. Khachatryan , G. W. Kluge , Y. Kobayashi , J. Konrad , P. M. Kouch , H. Kubo , J. Kushida , M. Lainez , A. Lamastra , E. Lindfors , S. Lombardi , F. Longo , R. Lopez-Coto , M. Lopez-Moya , A. Lopez-Oramas , S. Loporchio , A. Lorini , L. Lulic , E. Lyard , P. Majumdar , M. Makariev , G. Maneva , M. Manganaro , S. Mangano , K. Mannheim , M. Mariotti , M. Martinez , P. Maruševec , A. Mas-Aguilar , D. Mazin , S. Menchiari , S. Mender , D. Miceli , J. M. Miranda , R. Mirzoyan , M. Molero Gonzalez , E. Molina , H. A. Mondal , A. Moralejo , T. Nakamori , C. Nanci , V. Neustroev , L. Nickel , M. Nievas Rosillo , C. Nigro , L. Nikolic , K. Nilsson , K. Nishijima , T. Njoh Ekoume , K. Noda , S. Nozaki , A. Okumura , S. Paiano , D. Paneque , R. Paoletti , J. M. Paredes , L. Pavletic , M. Peresano , M. Persic , M. Pihet , G. Pirola , F. Podobnik , P. G. Prada Moroni , E. Prandini , G. Principe , W. Rhode , M. Ribo , J. Rico , C. Righi , N. Sahakyan , T. Saito , F. G. Saturni , K. Schmitz , F. Schmuckermaier , J. L. Schubert , A. Sciaccaluga , G. Silvestri , J. Sitarek , V. Sliusar , D. Sobczynska , A. Stamerra , J. Striškovic , D. Strom , M. Strzys , Y. Suda , H. Tajima , M. Takahashi , R. Takeishi , P. Temnikov , K. Terauchi , T. Terzic , M. Teshima , A. Tutone , S. Ubach , J. van Scherpenberg , M. Vazquez Acosta , S. Ventura , G. Verna , I. Viale , A. Vigliano , C. F. Vigorito , V. Vitale , I. Vovk , R. Walter , F. Wersig , M. Will , T. Yamamoto , C. Bartolini , E. Bissaldi , S. Garrappa , E. Ankara , N. Bader , M. Feige , F. Hümmer , F. Kaplan , C. Lorey , D. Reinhart , K. Schoch , R. Steineke , A. Marchini , V. Fallah Ramazani , M. J. Graham , T. Hovatta , S. Kiehlmann , A. C. S. Readhead , P. Benke , F. Eppel , S. Hammeric , J. Heßdörfer , M. Kadler , D. Kirchner , A. Gokus , G. F. Paraschos , F. Rösch , J. Sinapius

Multiwavelength periodicity search in a sample of $\gamma$-ray bright blazars

We present the results of a long-term periodicity search in a sample of $\gamma$-ray blazars within a multiwavelength context. These blazars have been selected from the Steward Observatory sample as part of its optical monitoring program…

High Energy Astrophysical Phenomena · Physics 2022-11-16 J. Otero-Santos , P. Peñil , J. A. Acosta-Pulido , J. Becerra González , C. M. Raiteri , M. I. Carnerero , M. Villata

High Frequency VLBI Rotation Measure of 8 AGN

We have studied Very Long Baseline Array (VLBA) polarimetric observations of 8 sources including quasars and BL Lacs at 12, 15, 22, 24 and 43 GHz and high frequency rotation measure ($RM$) maps are presented. We find typical values for the…

High Energy Astrophysical Phenomena · Physics 2015-06-12 J. C. Algaba

High-resolution radio imaging of two luminous quasars beyond redshift 4.5

Context. Radio-loud active galactic nuclei in the early Universe are rare. The quasars J0906+6930 at redshift z=5.47 and J2102+6015 at z=4.57 stand out from the known sample with their compact emission on milliarcsecond (mas) angular scale…

Astrophysics of Galaxies · Physics 2018-10-17 S. Frey , O. Titov , A. E. Melnikov , P. de Vicente , F. Shu

Imaging and variability studies of CTA~102 during the 2016 January $\gamma$-ray flare

The $\gamma$-ray bright blazar CTA 102 is studied using imaging (new 15 GHz and archival 43 GHz Very Long Baseline Array, VLBA data) and time variable optical flux density, polarization degree and electric vector position angle (EVPA)…

High Energy Astrophysical Phenomena · Physics 2018-02-21 Xiaofeng Li , P. Mohan , T. An , Xiaoyu Hong , Xiaopeng Cheng , Jun Yang , Yingkang Zhang , Zhongli Zhang , Wei Zhao

Multiwavelength study of the gravitationally lensed blazar QSO B0218+357 between 2016 and 2020

We report multiwavelength observations of the gravitationally lensed blazar QSO B0218+357 in 2016-2020. Optical, X-ray and GeV flares were detected. The contemporaneous MAGIC observations do not show significant very-high-energy (VHE, >=…

High Energy Astrophysical Phenomena · Physics 2022-02-02 MAGIC Collaboration , V. A. Acciari , S. Ansoldi , L. A. Antonelli , A. Arbet Engels , M. Artero , K. Asano , D. Baack , A. Babić , A. Baquero , U. Barres de Almeida , J. A. Barrio , I. Batković , J. Becerra González , W. Bednarek , L. Bellizzi , E. Bernardini , M. Bernardos , A. Berti , J. Besenrieder , W. Bhattacharyya , C. Bigongiari , A. Biland , O. Blanch , G. Bonnoli , Ž. Bošnjak , G. Busetto , R. Carosi , G. Ceribella , M. Cerruti , Y. Chai , A. Chilingarian , S. Cikota , S. M. Colak , E. Colombo , J. L. Contreras , J. Cortina , S. Covino , G. D'Amico , V. D'Elia , P. Da Vela , F. Dazzi , A. De Angelis , B. De Lotto , M. Delfino , J. Delgado , C. Delgado Mendez , D. Depaoli , F. Di Pierro , L. Di Venere , E. Do Souto Espiñeira , D. Dominis Prester , A. Donini , D. Dorner , M. Doro , D. Elsaesser , V. Fallah Ramazani , A. Fattorini , G. Ferrara , M. V. Fonseca , L. Font , C. Fruck , S. Fukami , R. J. García López , M. Garczarczyk , S. Gasparyan , M. Gaug , N. Giglietto , F. Giordano , P. Gliwny , N. Godinović , J. G. Green , D. Green , D. Hadasch , A. Hahn , L. Heckmann , J. Herrera , J. Hoang , D. Hrupec , M. Hütten , T. Inada , S. Inoue , K. Ishio , Y. Iwamura , I. Jiménez , J. Jormanainen , L. Jouvin , Y. Kajiwara , M. Karjalainen , D. Kerszberg , Y. Kobayashi , H. Kubo , J. Kushida , A. Lamastra , D. Lelas , F. Leone , E. Lindfors , S. Lombardi , F. Longo , R. López-Coto , M. López-Moya , A. López-Oramas , S. Loporchio , B. Machado de Oliveira Fraga , C. Maggio , P. Majumdar , M. Makariev , M. Mallamaci , G. Maneva , M. Manganaro , K. Mannheim , L. Maraschi , M. Mariotti , M. Martínez , D. Mazin , S. Menchiari , S. Mender , S. Mićanović , D. Miceli , T. Miener , M. Minev , J. M. Miranda , R. Mirzoyan , E. Molina , A. Moralejo , D. Morcuende , V. Moreno , E. Moretti , V. Neustroev , C. Nigro , K. Nilsson , K. Nishijima , K. Noda , S. Nozaki , Y. Ohtani , T. Oka , J. Otero-Santos , S. Paiano , M. Palatiello , D. Paneque , R. Paoletti , J. M. Paredes , L. Pavletić , P. Peñil , C. Perennes , M. Persic , P. G. Prada Moroni , E. Prandini , C. Priyadarshi , I. Puljak , W. Rhode , M. Ribó , J. Rico , C. Righi , A. Rugliancich , L. Saha , N. Sahakyan , T. Saito , S. Sakurai , K. Satalecka , F. G. Saturni , B. Schleicher , K. Schmidt , T. Schweizer , J. Sitarek , I. Šnidarić , D. Sobczynska , A. Spolon , A. Stamerra , D. Strom , M. Strzys , Y. Suda , T. Surić , M. Takahashi , F. Tavecchio , P. Temnikov , T. Terzić , M. Teshima , L. Tosti , S. Truzzi , A. Tutone , S. Ubach , J. van Scherpenberg , G. Vanzo , M. Vazquez Acosta , S. Ventura , V. Verguilov , C. F. Vigorito , V. Vitale , I. Vovk , M. Will , C. Wunderlich , D. Zarić , F. de Palma , F. D'Ammando , A. Barnacka , D. K. Sahu , M. Hodges , T. Hovatta , S. Kiehlmann , W. Max-Moerbeck , A. C. S. Readhead , R. Reeves , T. J. Pearson , A. Lähteenmäki , I. Björklund , M. Tornikoski , J. Tammi , S. Suutarinen , K. Hada , K. Niinuma

A decade of multi-wavelength observations of the TeV blazar 1ES 1215+303: Extreme shift of the synchrotron peak frequency and long-term optical-gamma-ray flux increase

Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and…

High Energy Astrophysical Phenomena · Physics 2020-03-23 Janeth Valverde , Deirdre Horan , Denis Bernard , Stephen Fegan , A. U. Abeysekara , A. Archer , W. Benbow , R. Bird , A. Brill , R. Brose , M. Buchovecky , J. H. Buckley , J. L. Christiansen , W. Cui , A. Falcone , Q. Feng , J. P. Finley , L. Fortson , A. Furniss , A. Gent , G. H. Gillanders , C. Giuri , O. Gueta , D. Hanna , T. Hassan , O. Hervet , J. Holder , G. Hughes , T. B. Humensky , P. Kaaret , N. Kelley-Hoskins , M. Kertzman , D. Kieda , M. Krause , F. Krennrich , M. J. Lang , G. Maier , P. Moriarty , R. Mukherjee , D. Nieto , M. Nievas-Rosillo , S. O'Brien , R. A. Ong , A. N. Otte , N. Park , A. Petrashyk , K. Pfrang , A. Pichel , M. Pohl , R. R. Prado , E. Pueschel , J. Quinn , K. Ragan , P. T. Reynolds , D. Ribeiro , G. T. Richards , E. Roache , I. Sadeh , M. Santander , S. S. Scott , G. H. Sembroski , K. Shahinyan , R. Shang , I. Sushch , V. V. Vassiliev , A. Weinstein , R. M. Wells , P. Wilcox , A. Wilhelm , D. A. Williams , T. J Williamson , Giuliana Noto , P. G. Edwards , B. G. Piner , V. Fallah Ramazani , T. Hovatta , J. Jormanainen , E. Lindfors , K. Nilsson , L. Takalo , Y. Y. Kovalev , M. L. Lister , A. B. Pushkarev , T. Savolainen , S. Kiehlmann , W. Max-Moerbeck , A. C. S. Readhead , A. Lähteenmäki , M. Tornikoski

0FGL J1830.3+0617: A Fermi Blazar Near the Galactic Plane

We present a multiwavelength study of the unidentified Fermi gamma-ray source 0FGL J1830.3+0617, which exhibits variability above 200 MeV on timescales of days to weeks. Within the Fermi 95% confidence error contour lies B1827+0617, a radio…

High Energy Astrophysical Phenomena · Physics 2009-08-12 N. Mirabal , J. P. Halpern

Unravelling the Innermost Jet Structure of OJ 287 with the First GMVA+ALMA Observations

We present the first very-long-baseline interferometric (VLBI) observations of the blazar OJ287 carried out jointly with the Global Millimeter VLBI Array (GMVA) and the phased Atacama Large Millimeter/submillimeter Array (ALMA) at 3.5 mm on…

High Energy Astrophysical Phenomena · Physics 2022-06-17 Guang-Yao Zhao , Jose L. Gomez , Antonio Fuentes , Thomas P. Krichbaum , E. Traianou , Rocco Lico , Ilje Cho , Eduardo Ros , S. Komossa , Kazunori Akiyama , Keiichi Asada , Lindy Blackburn , Silke Britzen , Gabriele Bruni , Geoffrey Crew , Rohan Dahale , Lankeswar Dey , Roman Gold , Achamveedu Gopakumar , Sara Issaoun , Michael Janssen , Svetlana G. Jorstad , Jae-Young Kim , Jun Yi Koay , Yuri Y. Kovalev , Shoko Koyama , Andrei Lobanov , Laurent Loinard , Rusen Lu , Sera Markoff , Alan P. Marscher , Ivan Marti-Vidal , Yosuke Mizuno , Jongho Park , Tuomas Savolainen , Teresa Toscano

A simplified view of blazars: the very high energy gamma-ray vision

We have recently proposed a simplified scenario for blazars in which these sources are classified as flat-spectrum radio quasars or BL Lacs according to the prescriptions of unified schemes, and to a varying combination of Doppler boosted…

High Energy Astrophysical Phenomena · Physics 2015-06-23 P. Padovani , P. Giommi

VLBI detection of nearby (< 100 pc) young stars: Pilot observations

To increase the number of sources with Very Long Baseline Interferometry (VLBI) astrometry available for comparison with the Gaia results, we have observed 31 young stars with recently reported radio emission. These stars are all in the…

Solar and Stellar Astrophysics · Physics 2024-06-12 Sergio A. Dzib , Laurent Loinard , Ralf Launhardt , Jazmín Ordóñez-Toro

The Central Parsecs of the Bright Quasar PKS 1921 - 293

We report on a VLBA imaging study of the nearby bright southern blazar PKS 1921 - 293 (OV - 236). High resolution VLBA observations, made at four frequencies (5, 12, 15, and 43 GHz) over the period 1994 - 2000, have revealed a strongly…

Astrophysics · Physics 2007-05-23 Z. -Q. Shen , J. M. Moran , K. I. Kellermann

An Overview of Blazar Variability

Blazars are characterized by rapid variability at virtually all wavelengths from radio through TeV gamma-rays. The challenge since their discovery has been to understand the origin of their luminous, apparently nonthermal, nuclear emission.…

Astrophysics · Physics 2007-05-23 C. Megan Urry

Correlation analysis between several observables of OJ 287 radio jet

We collected the archival data of blazar OJ~287 from heterogeneous very long baseline interferometry (VLBI) monitoring programs at 2.3 GHz, 8.6 GHz, 15 GHz and 43 GHz. The data reduction and observable extraction of those multi-band…

Astrophysics of Galaxies · Physics 2023-04-04 Qi Yuan , Ming Zhang , Xiang Liu , Pengfei Jiang , Gulchehra I. Kokhirova

Very Long Baseline Array Imaging of Type-2 Seyferts with Double-Peaked Narrow Emission Lines: Searches for Sub-kpc Dual AGNs and Jet-Powered Outflows

This paper presents Very Long Baseline Array (VLBA) observations of 13 double-peaked [O III] emission-line type-2 Active Galactic Nuclei (AGNs) at redshifts 0.06 < z < 0.41 (with a median redshift of z~0.15) identified in the Sloan Digital…

Astrophysics of Galaxies · Physics 2018-03-14 Xin Liu , T. Joseph W. Lazio , Yue Shen , Michael A. Strauss

X-ray and Radio Follow-up Observations of High-Redshift Blazar Candidates in the Fermi-LAT Unassociated Source Population

We report on the results of X-ray and radio follow-up observations of two GeV gamma-ray sources 2FGL J0923.5+1508 and 2FGL J1502.1+5548, selected as candidates for high-redshift blazars from unassociated sources in the {\it Fermi} Large…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Y. Takahashi , J. Kataoka , K. Niinuma , M. Honma , Y. Inoue , T. Totani , S. Inoue , T. Nakamori , K. Maeda