Related papers: High redshift Fermi blazars observed by GROND and …

Gamma-ray blazars: the view from AGILE

During the first 3 years of operation the Gamma-Ray Imaging Detector onboard the AGILE satellite detected several blazars in a high gamma-ray activity: 3C 279, 3C 454.3, PKS 1510-089, S5 0716+714, 3C 273, W Comae, Mrk 421, PKS 0537-441 and…

High Energy Astrophysical Phenomena · Physics 2019-08-15 F. D'Ammando , A. Bulgarelli , A. W. Chen , I. Donnarumma , A. Giuliani , F. Longo , L. Pacciani , G. Pucella , E. Striani , M. Tavani , S. Vercellone , V. Vittorini , S. Covino , H. A. Krimm , C. M. Raiteri , P. Romano , M. Villata

15 GHz Monitoring of Gamma-ray Blazars with the OVRO 40 Meter Telescope in Support of Fermi

We present results from the first two years of our fast-cadence 15 GHz gamma-ray blazar monitoring program, part of the F-GAMMA radio monitoring project. Our sample includes the 1158 blazars north of -20 degrees declination from the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 J. L. Richards , W. Max-Moerbeck , V. Pavlidou , T. J. Pearson , A. C. S. Readhead , M. A. Stevenson , S. E. Healey , R. W. Romani , M. S. Shaw , L. Fuhrmann , E. Angelakis , J. A. Zensus , K. Grainge , G. B. Taylor

Optical spectroscopy of the gamma-ray bright blazars PKS 0447-439 and PMN J0630-24

The large majority of sources detected by the Fermi Gamma-ray Space Telescope are blazars, belonging in particular to the blazar subclass of BL Lacertae objects (BL Lacs). BL Lacs often have featureless optical spectra, which make it…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Hermine Landt

The Cross-Calibration of Swift-BAT and Fermi-GBM via Correlative Spectral Analysis of GRBs

We report on recent inter-calibration studies featuring Swift's Burst Alert Telescope (BAT) and Fermi's Gamma-ray Burst Monitor (GBM) based upon correlated observations of GRBs 080804 and 080810, via their resultant joint spectral analysis.…

High Energy Astrophysical Phenomena · Physics 2009-07-21 Michael Stamatikos

Chandra Survey of Radio-quiet, High-redshift Quasars

We observed 17 optically-selected, radio-quiet high-redshift quasars with the Chandra Observatory ACIS, and detected 16 of them. The quasars have redshift between 3.70 and 6.28 and include the highest redshift quasars known. When compared…

Astrophysics · Physics 2008-11-26 Jill Bechtold , Aneta Siemiginowska , Joseph Shields , Bozena Czerny , Agnieszka Janiuk , Fred Hamann , Thomas L. Aldcroft , Martin Elvis , Adam Dobrzycki

The Contrasting Nature of Gamma-Ray/Optical Variability in the Blazar PKS 0208-512 During Successive Outbursts

The Yale/SMARTS optical-near-IR monitoring program has followed the variations in emission of the Fermi-LAT monitored blazars in the southern sky with closely spaced observations since 2008. We report the discovery of an optical-near-IR…

High Energy Astrophysical Phenomena · Physics 2013-03-11 Ritaban Chatterjee , G. Fossati , C. M. Urry , C. D. Bailyn , L. Maraschi , M. Buxton , E. W. Bonning , J. Isler , P. Coppi

Swift/XRT observes the fifth outburst of the periodic Supergiant Fast X-ray Transient IGR J11215-5952

IGR J11215-5952 is a hard X-ray transient source discovered in April 2005 with INTEGRAL and a confirmed member of the new class of High Mass X-ray Binaries, the Supergiant Fast X-ray Transients (SFXTs). Archival INTEGRAL data and RXTE…

Astrophysics · Physics 2007-06-13 P. Romano , L. Sidoli , V. Mangano , S. Mereghetti , G. Cusumano

Blue Fermi Flat Spectrum Radio Quasars

Many blazars detected by the Fermi satellite, observed spectroscopically in the optical, are line-less, and have been classified as BL Lac objects. Optical-UV photometry of nearly one hundred of them allowed to determine the redshift for a…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 G. Ghisellini , F. Tavecchio , L. Foschini , T. Sbarrato , G. Ghirlanda , L. Maraschi

Fermi Observations of Blazars: Implications for Gamma-ray Production

The brightest blazars detected by the Fermi Gamma-ray Space Telescope Large Area Telescope (Fermi/LAT) show significant breaks in their spectra at a few GeV. The sharpness and the position of the breaks can be well reproduced by absorption…

Cosmology and Nongalactic Astrophysics · Physics 2012-02-08 Juri Poutanen , Boris E. Stern

Swift panchromatic observations of the bright gamma-ray burst GRB050525a

The bright gamma-ray burst GRB050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UV afterglow decay light curves both exhibit a…

Astrophysics · Physics 2019-08-14 A. J. Blustin , D. Band , S. Barthelmy , P. Boyd , M. Capalbi , S. T. Holland , F. E. Marshall , K. O. Mason , M. Perri , T. Poole , P. Roming , S. Rosen , P. Schady , M. Still , B. Zhang

VERITAS Observations of Gamma-Ray Bursts Detected by Swift

We present the results of sixteen Swift-triggered GRB follow-up observations taken with the VERITAS telescope array from January, 2007 to June, 2009. The median energy threshold and response time of these observations was 260 GeV and 320 s,…

High Energy Astrophysical Phenomena · Physics 2015-05-30 VERITAS Collaboration , V. A. Acciari , E. Aliu , T. Arlen , T. Aune , M. Beilicke , W. Benbow , S. M. Bradbury , J. H. Buckley , V. Bugaev , K. Byrum , A. Cannon , A. Cesarini , J. L. Christiansen , L. Ciupik , E. Collins-Hughes , M. P. Connolly , W. Cui , 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 , G. Hughes , C. M. Hui , T. B. Humensky , D. J. Jackson , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , A. S Madhavan , G. Maier , S. McArthur , A. McCann , P. Moriarty , M. D. Newbold , R. A. Ong , M. Orr , A. N. Otte , N. Park , J. S. Perkins , 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 , A. W. Smith , D. Staszak , S. P. Swordy , G. Tešić , M. Theiling , S. Thibadeau , K. Tsurusaki , 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 , M. Wood

VERITAS Observations of Six Bright, Hard-Spectrum Fermi-LAT Blazars

We report on VERITAS very-high-energy (VHE; E>100 GeV) observations of six blazars selected from the Fermi Large Area Telescope First Source Catalog (1FGL). The gamma-ray emission from 1FGL sources was extrapolated up to the VHE band,…

High Energy Astrophysical Phenomena · Physics 2015-06-11 E. Aliu , S. Archambault , T. Arlen , T. Aune , M. Beilicke , W. Benbow , M. Bottcher , A. Bouvier , J. H. Buckley , V. Bugaev , A. Cesarini , L. Ciupik , E. Collins-Hughes , M. P. Connolly , W. Cui , R. Dickherber , C. Duke , J. Dumm , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , S. Godambe , S. Griffin , J. Grube , G. Gyuk , D. Hanna , J. Holder , H. Huan , P. Kaaret , N. Karlsson , Y. Khassen , D. Kieda , H. Krawczynski , F. Krennrich , K. Lee , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , P. Moriarty , R. Mukherjee , T. Nelson , A. O'Faolain de Bhroithe , 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 , D. B. Saxon , G. H. Sembroski , D. Staszak , I. Telezhinsky , G. Tesic , M. Theiling , S. Thibadeau , K. Tsurusaki , A. Varlotta , V. V. Vassiliev , S. Vincent , M. Vivier , S. P. Wakely , T. C. Weekes , A. Weinstein , R. Welsing , D. A. Williams , B. Zitzer , P. Fortin , D. Horan , M. Fumagalli , K. Kaplan , J. X. Prochaska

Optical and near-infrared follow-up observations of four Fermi/LAT GRBs : Redshifts, afterglows, energetics and host galaxies

Fermi can measure the spectral properties of gamma-ray bursts over a very large energy range and is opening a new window on the prompt emission of these energetic events. Localizations by the instruments on Fermi in combination with…

High Energy Astrophysical Phenomena · Physics 2015-03-13 S. McBreen , T. Krühler , A. Rau , J. Greiner , D. A. Kann , S. Savaglio , P. Afonso , C. Clemens , R. Filgas , S. Klose , A. Küpüc Yoldas , F. Olivares E. , A. Rossi , G. P. Szokoly , A. Updike , A. Yoldas

A Systematic Search for Spectral Hardening in Blazar Flares with the Fermi-Large Area Telescope

Blazars are a subclass of active galactic nuclei (AGN) that emit non-thermal radiation through relativistic jets, characterized by rapid flux and polarization variability. High synchrotron-peaked blazars (HSPs) and extreme high…

High Energy Astrophysical Phenomena · Physics 2025-11-26 Adithiya Dinesh , Alberto Dominguez , V. Paliya , J. L. Contreras , S. Buson , M. Ajello

20 years of monitoring: PKS 2155-304 and PKS 1510-089 in the eyes of Swift and Fermi. II. PKS 1510-089 and comparison

We present a comprehensive, two-decade, multiwavelength variability study of the blazar PKS 1510-089, one of the most prominent and extensively monitored flat-spectrum radio quasars. Using Fermi-LAT $\gamma$-ray data together with Swift-XRT…

High Energy Astrophysical Phenomena · Physics 2026-04-02 M. Zacharias , A. Wierzcholska

Multi-wavelength variability of CGRaBS J0733+0456: identifying a distant $\gamma$-ray blazar at z = 3.01

We report on OVRO, WISE, Swift and Fermi-LAT observations of the high redshift blazar CGRaBS J0733+0456, from which significant flux variations in radio, infrared (IR) as well as $\gamma$-ray domains are detected. Particularly, the…

High Energy Astrophysical Phenomena · Physics 2019-07-10 Neng-Hui Liao , Li-Ming Dou , Ning Jiang , Yi-Bo Wang , Yi-Zhong Fan , Ting-Gui Wang

Five High-Redshift Quasars Discovered in Commissioning Imaging Data of the Sloan Digital Sky Survey

We report the discovery of five quasars with redshifts of 4.67 - 5.27 and z'-band magnitudes of 19.5-20.7 M_B ~ -27. All were originally selected as distant quasar candidates in optical/near-infrared photometry from the Sloan Digital Sky…

Astrophysics · Physics 2009-10-31 W. Zheng , Z. I. Tsvetanov , D. P. Schneider , X. Fan , R. H. Becker , M. Davis , R. L. White , M. A. Strauss , J. Annis , N. A. Bahcall , A. J. Connolly , I. Csabai , A. F. Davidsen , M. Fukugita , J. E. Gunn , T. M. Heckman , G. S. Hennessy , Z. Ivezic , G. R. Knapp , E. Peng , A. S. Szalay , A. R. Thakar , B. Yanny , D. G. York

The Discovery of gamma-Ray Emission From The Blazar RGB J0710+591

The high-frequency-peaked BL Lacertae object RGB J0710+591 was observed in the very high-energy (VHE; E > 100 GeV) wave band by the VERITAS array of atmospheric Cherenkov telescopes. The observations, taken between 2008 December and 2009…

High Energy Astrophysical Phenomena · Physics 2015-05-18 V. A. Acciari , E. Aliu , T. Arlen , T. Aune , M. Bautista , M. Beilicke , W. Benbow , M. Böttcher , D. Boltuch , S. M. Bradbury , J. H. Buckley , V. Bugaev , K. Byrum , A. Cannon , A. Cesarini , L. Ciupik , W. Cui , R. Dickherber , C. Duke , A. Falcone , J. P. Finley , G. Finnegan , L. Fortson , A. Furniss , N. Galante , D. Gall , K. Gibbs , G. H. Gillanders , S. Godambe , J. Grube , R. Guenette , G. Gyuk , D. Hanna , J. Holder , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. Kieda , A. Konopelko , H. Krawczynski , F. Krennrich , M. J. Lang , A. Lamerato , S. LeBohec , G. Maier , S. McArthur , A. McCann , M. McCutcheon , P. Moriarty , R. Mukherjee , R. A. Ong , A. N. Otte , D. Pandel , J. S. Perkins , D. Petry , A. Pichel , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , P. Roustazadeh , M. Schroedter , G. H. Sembroski , G. Demet Senturk , A. W. Smith , D. Steele , S. P. Swordy , G. Tešić , M. Theiling , S. Thibadeau , A. Varlotta , V. V. Vassiliev , S. Vincent , R. G. Wagner , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , T. Weisgarber , D. A. Williams , S. Wissel , M. Wood , B. Zitzer , M. Ackermann , M. Ajello , E. Antolini , L. Baldini , J. Ballet , G. Barbiellini , D. Bastieri , K. Bechtol , R. Bellazzini , B. Berenji , R. D. Blandford , E. D. Bloom , E. Bonamente , A. W. Borgland , A. Bouvier , J. Bregeon , M. Brigida , P. Bruel , R. Buehler , S. Buson , G. A. Caliandro , R. A. Cameron , P. A. Caraveo , S. Carrigan , J. M. Casandjian , E. Cavazzuti , C. Cecchi , Ö. Çelik , E. Charles , A. Chekhtman , C. C. Cheung , J. Chiang , S. Ciprini , R. Claus , J. Cohen-Tanugi , J. Conrad , C. D. Dermer , F. de Palma , E. do Couto e Silva , P. S. Drell , R. Dubois , D. Dumora , C. Farnier , C. Favuzzi , S. J. Fegan , P. Fortin , M. Frailis , Y. Fukazawa , S. Funk , P. Fusco , F. Gargano , D. Gasparrini , N. Gehrels , S. Germani , B. Giebels , N. Giglietto , F. Giordano , M. Giroletti , T. Glanzman , G. Godfrey , I. A. Grenier , J. E. Grove , S. Guiriec , E. Hays , D. Horan , R. E. Hughes , G. Jóhannesson , A. S. Johnson , W. N. Johnson , T. Kamae , H. Katagiri , J. Kataoka , J. Knödlseder , M. Kuss , J. Lande , L. Latronico , S. -H. Lee , M. Llena Garde , F. Longo , F. Loparco , B. Lott , M. N. Lovellette , P. Lubrano , A. Makeev , M. N. Mazziotta , P. F. Michelson , W. Mitthumsiri , T. Mizuno , A. A. Moiseev , C. Monte , M. E. Monzani , A. Morselli , I. V. Moskalenko , S. Murgia , P. L. Nolan , J. P. Norris , E. Nuss , M. Ohno , T. Ohsugi , N. Omodei , E. Orlando , J. F. Ormes , D. Paneque , J. H. Panetta , V. Pelassa , M. Pepe , M. Pesce-Rollins , F. Piron , T. A. Porter , S. Rainò , R. Rando , M. Razzano , A. Reimer , O. Reimer , J. Ripken , A. Y. Rodriguez , M. Roth , H. F. -W. Sadrozinski , D. Sanchez , A. Sander , J. D. Scargle , C. Sgrò , E. J. Siskind , P. D. Smith , G. Spandre , P. Spinelli , M. S. Strickman , D. J. Suson , H. Takahashi , T. Tanaka , J. B. Thayer , J. G. Thayer , D. J. Thompson , L. Tibaldo , D. F. Torres , G. Tosti , A. Tramacere , T. L. Usher , V. Vasileiou , N. Vilchez , V. Vitale , A. P. Waite , P. Wang , B. L. Winer , K. S. Wood , Z. Yang , T. Ylinen , M. Ziegler

A Blind Search for Prompt Gamma-ray Counterparts of Fast Radio Bursts with Fermi-LAT Data

Fast Radio Bursts (FRBs) are a mysterious flash phenomenon detected in radio wavelengths with a duration of only a few milliseconds, and they may also have prompt gamma-ray flashes. Here we carry out a blind search for msec-duration…

High Energy Astrophysical Phenomena · Physics 2019-06-07 Shotaro Yamasaki , Tomonori Totani , Norita Kawanaka

A significant hardening and rising shape detected in the MeV/GeV nuFnu spectrum from the recently-discovered very-high-energy blazar S4 0954+65 during the bright optical flare in 2015 February

We report on Fermi Large Area Telescope (LAT) and multi-wavelength results on the recently-discovered very-high-energy (VHE, $E>$ 100 GeV) blazar S4 0954+65 ($z=0.368$) during an exceptionally bright optical flare in 2015 February. During…

High Energy Astrophysical Phenomena · Physics 2016-06-01 Y. T. Tanaka , J. Becerra Gonzalez , R. Itoh , J. D. Finke , Y. Inoue , R. Ojha , B. Carpenter , E. Lindfors , F. Krauss , R. Desiante , K. Shiki , Y. Fukazawa , F. Longo , J. McEnery , S. Buson , K. Nilsson , V. Fallah Ramazani , R. Reinthal , L. Takalo , T. Pursimo , W. Boschin