Related papers: Discovery and identification of two gamma-ray blaz…

VERITAS Long-Term Observations of Hard Spectrum Blazars

The VERITAS collaboration has approved long-term observations on several distant, hard-spectrum blazars. We present first results from VERITAS long-term observations of 1ES1218+304, 1ES0229+200, and 1ES0414+009. Gamma-ray observations of…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Arun S. Madhavan

A gamma-ray flare from TXS 1508+572: characterizing the jet of a $z=4.31$ blazar in the early Universe

Blazars can be detected from very large distances due to their high luminosity. However, the detection of $\gamma$-ray emission of blazars beyond $z=3$ has only been confirmed for a small number of sources. Such observations probe the…

High Energy Astrophysical Phenomena · Physics 2024-08-05 Andrea Gokus , Markus Böttcher , Manel Errando , Michael Kreter , Jonas Heßdörfer , Florian Eppel , Matthias Kadler , Paul S. Smith , Petra Benke , Leonid I. Gurvits , Alex Kraus , Mikhail Lisakov , Felicia McBride , Eduardo Ros , Florian Rösch , Jörn Wilms

The BL-Lac gamma-ray blazar PKS 1424+240 associated with a group of galaxies at z=0.6010

PKS 1424+240 is a BL-Lac blazar with unknown redshift that was detected at high-energy gamma rays by Fermi-LAT with a hard spectrum. At VHE, it was first detected by VERITAS and later confirmed by MAGIC. Its spectral energy distribution is…

High Energy Astrophysical Phenomena · Physics 2016-04-20 A. C. Rovero , H. Muriel , C. Donzelli , A. Pichel

A luminous and isolated gamma-ray flare from the blazar B2 1215+30

B2 1215+30 is a BL Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes, and subsequently confirmed by the VERITAS observatory with data collected between 2009 and 2012. In 2014 February 08,…

High Energy Astrophysical Phenomena · Physics 2017-02-23 VERITAS Collaboration , A. U. Abeysekara , S. Archambault , A. Archer , W. Benbow , R. Bird , M. Buchovecky , J. H. Buckley , V. Bugaev , K. Byrum , M. Cerruti , X. Chen , L. Ciupik , W. Cui , H. J. Dickinson , J. D. Eisch , M. Errando , A. Falcone , Q. Feng , J. P. Finley , H. Fleischhack , L. Fortson , A. Furniss , G. H. Gillanders , S. Griffin , J. Grube , M. Hutten , N. Hakansson , D. Hanna , J. Holder , T. B. Humensky , C. A. Johnson , P. Kaaret , P. Kar , M. Kertzman , D. Kieda , M. Krause , F. Krennrich , S. Kumar , M. J. Lang , G. Maier , S. McArthur , A. McCann , K. Meagher , P. Moriarty , R. Mukherjee , T. Nguyen , D. Nieto , R. A. Ong , A. N. Otte , N. Park , V. Pelassa , M. Pohl , A. Popkow , E. Pueschel , J. Quinn , K. Ragan , P. T. Reynolds , G. T. Richards , E. Roache , C. Rulten , M. Santander , G. H. Sembroski , K. Shahinyan , D. Staszak , I. Telezhinsky , J. V. Tucci , J. Tyler , S. P. Wakely , O. M. Weiner , A. Weinstein , A. Wilhelm , D. A. Williams , Fermi-LAT Collaboration , : , S. Fegan , B. Giebels , D. Horan , A. Berdyugin , J. Kuan , E. Lindfors , K. Nilsson , A. Oksanen , H. Prokoph , R. Reinthal , L. Takalo , F. Zefi

Highlights from VERITAS on VHE Gamma-ray Sources in our Galaxy

VERITAS is a major ground-based detector of very high energy (VHE, E > 100 GeV) gamma rays and cosmic rays. VERITAS consists of an ar- ray of four 12m-diameter atmospheric Cherenkov telescopes that has been fully operational since September…

High Energy Astrophysical Phenomena · Physics 2019-08-13 Rene A. Ong

Long term observations of B2 1215+30 with VERITAS

We report on VERITAS observations of the BL Lac object B2 1215+30 between 2008 and 2012. During this period, the source was detected at very high energies (VHE; E > 100 GeV) by VERITAS with a significance of $8.9\sigma$ and showed clear…

High Energy Astrophysical Phenomena · Physics 2015-06-17 VERITAS collaboration , E. Aliu , S. Archambault , T. Arlen , T. Aune , M. Beilicke , W. Benbow , R. Bird , A. Bouvier , J. H. Buckley , V. Bugaev , A. Cesarini , L. Ciupik , M. P. Connolly , W. Cui , J. Dumm , M. Errando , A. Falcone , S. Federici , Q. Feng , J. P. Finley , P. Fortin , L. Fortson , A. Furniss , N. Galante , L. Gérard , G. H. Gillanders , S. Griffin , J. Grube , G. Gyuk , D. Hanna , J. Holder , G. Hughes , T. B. Humensky , P. Kaaret , M. Kertzman , Y. Khassen , D. Kieda , H. Krawczynski , F. Krennrich , M. J. Lang , A. S Madhavan , G. Maier , P. Majumdar , S. McArthur , A. McCann , P. Moriarty , R. Mukherjee , D. Nieto , A. O'Faoláin de Bhróithe , R. A. Ong , M. Orr , A. N. Otte , N. Park , J. S. Perkins , M. Pohl , A. Popkow , H. Prokoph , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , G. T. Richards , E. Roache , D. B. Saxon , G. H. Sembroski , C. Skole , A. W. Smith , M. Soares-Furtado , D. Staszak , I. Telezhinsky , G. Tešić , M. Theiling , A. Varlotta , V. V. Vassiliev , S. Vincent , S. P. Wakely , T. C. Weekes , A. Weinstein , R. Welsing , D. A. Williams , B. Zitzer , M. Böttcher , M. Fumagalli , J. Jadhav

$Fermi$-LAT detection of a transient $\gamma$-ray source in the direction of a distant blazar B3 1428+422 at $z =4.72$

We report the detection of a transient $\gamma$-ray source in the direction of B3 1428+422 ($z=4.72$) by analyzing the 110-month {\it Fermi}-LAT Pass 8 data. The new transient $\gamma-$ray source is far away from the Galactic plane and has…

High Energy Astrophysical Phenomena · Physics 2018-10-10 Neng-Hui Liao , Shang Li , Yi-Zhong Fan

A Neutron-Star Identification for the High-Energy Gamma-ray Source 3EG J1835+5918 Detected in the ROSAT All-Sky Survey

In the error box of 3EG J1835+5918, the brightest as-yet unidentified EGRET source at intermediate Galactic latitude, we find a weak, ultrasoft X-ray source at energies E < 0.3 keV in the ROSAT All-Sky Survey. Deep optical imaging at the…

Astrophysics · Physics 2009-10-31 N. Mirabal , J. P. Halpern

Disentangling the nature of the prototype radio weak BL Lac: Contemporaneous multifrequency observations of WISE J141046.00 + 740511.2

Context. The gamma-ray emitting source WISE J141046.00+740511.2 has been associated with a Fermi-LAT detection by crossmatching with Swift/XRT data. It has shown all the canonical observational characteristics of a BL Lac source, including…

High Energy Astrophysical Phenomena · Physics 2023-02-15 E. J. Marchesini , V. Reynaldi , F. Vieyro , J. Saponara , I. Andruchow , I. E. López , P. Benaglia , S. A. Cellone , N. Masetti , F. Massaro , H. A. Peña-Herazo , V. Chavushyan , J. A. Combi , J. A. Acosta-Pulido , B. Agís González , N. Castro-Segura

Another X-ray-Discovered Poor Cluster of Galaxies Associated with CL 0016+16

We report optical spectroscopic observations of RX J0018.8+1602, a ROSAT X-ray source proposed to be an intermediate redshift cluster of galaxies. Our observations confirm the identification of RX J0018.8+1602 and provide measurements of…

Astrophysics · Physics 2009-10-30 John P. Hughes , Mark Birkinshaw

Systematic search for VHE gamma-ray emission from X-ray bright high-frequency BL Lac objects

All but three (M87, BL Lac and 3C 279) extragalactic sources detected so far at very high energy (VHE) gamma-rays belong to the class of high-frequency peaked BL Lac (HBL) objects. This suggested to us a systematic scan of candidate sources…

Astrophysics · Physics 2019-08-12 M. Meyer

Unveiling the nature of the gamma-ray emitting AGN PKS 0521-36

PKS 0521-36 is an Active Galactic Nucleus (AGN) with uncertain classification. We investigate the properties of this source from radio to gamma rays. The broad emission lines in the optical and UV bands and steep radio spectrum indicate a…

High Energy Astrophysical Phenomena · Physics 2015-11-11 F. D'Ammando , M. Orienti , F. Tavecchio , G. Ghisellini , E. Torresi , M. Giroletti , C. M. Raiteri , P. Grandi , M. Aller , H. Aller , M. A. Gurwell , G. Malaguti , E. Pian , G. Tosti

VHE Observations of the Binary Candidate HESS J0632+057 with H.E.S.S. and VERITAS

HESS J0632+057 is an unidentified gamma-ray source located in the Monoceros region, probably associated with the massive Be star MWC 148. H.E.S.S. and VERITAS observations in the very high energy (VHE) range combined with Swift X-ray data…

High Energy Astrophysical Phenomena · Physics 2019-08-15 Gernot Maier , Joanna Skilton

High energy gamma-ray sources in the VVV survey - III. Spectroscopic confirmation of an AGN at low Galactic latitudes

We aim to spectroscopically confirm the nature of VVV-J181258.71-314346.7, a candidate counterpart to the unassociated gamma-ray source 4FGLJ1812.8-3144. This object was selected based on its near-infrared photometric properties and…

Astrophysics of Galaxies · Physics 2025-10-07 Eduardo O. Schmidt , Laura D. Baravalle , Ana Pichel , Damián Mast , María Victoria Alonso , Jorge Díaz Tello , Luciano H. García , Valentin D. Ivanov , Dante Minniti , Nicola Masetti , Laura G. Donoso , Rodrigo Zelada Bacigalupo

HAWC, VERITAS, Fermi-LAT and XMM-Newton follow-up observations of the unidentified ultra-high-energy gamma-ray source LHAASO J2108+5157

We report observations of the ultra-high-energy gamma-ray source LHAASO J2108$+$5157, utilizing VERITAS, HAWC, Fermi-LAT, and XMM-Newton. VERITAS has collected $\sim$ 40 hours of data that we used to set ULs to the emission above 200 GeV.…

High Energy Astrophysical Phenomena · Physics 2025-08-27 The VERITAS collaboration , C. B. Adams , P. Bangale , W. Benbow , J. H. Buckley , Y. Chen , J. L. Christiansen , A. J. Chromey , M. Escobar Godoy , S. Feldman , Q. Feng , J. Foote , L. Fortson , A. Furniss , W. Hanlon , O. Hervet , C. E. Hinrichs , J. Holder , Z. Hughes , T. B. Humensky , W. Jin , P. Kaaret , M. Kertzman , M. Kherlakian , D. Kieda , T. K. Kleiner , N. Korzoun , S. Kumar , M. J. Lang , M. Lundy , G. Maier , M. J. Millard , P. Moriarty , R. Mukherjee , W. Ning , R. A. Ong , M. Pohl , E. Pueschel , J. Quinn , P. L. Rabinowitz , K. Ragan , P. T. Reynolds , D. Ribeiro , E. Roache , I. Sadeh , L. Saha , G. H. Sembroski , R. Shang , D. Tak , A. K. Talluri , J. V. Tucci , J. Valverde , D. A. Williams , S. L. Wong , J. Woo The HAWC collaboration , : , R. Alfaro , C. Alvarez , J. C. Arteaga-Vel'azquez , D. Avila Rojas , R. Babu , E. Belmont-Moreno , A. Bernal , K. S. Caballero-Mora , A. Carramiñana , S. Casanova , U. Cotti , J. Cotzomi , E. De la Fuente , C. de León , D. Depaoli , P. Desiati , N. Di Lalla , R. Diaz Hernandez , M. A. DuVernois , K. Engel , T. Ergin , C. Espinoza , K. L. Fan , N. Fraija , S. Fraija , J. A. García-González , F. Garfias , A. Gonzalez Muñoz , M. M. González , J. A. Goodman , S. Groetsch , J. P. Harding , S. Hernández-Cadena , I. Herzog , D. Huang , F. Hueyotl-Zahuantitla , P. Hüntemeyer , A. Iriarte , S. Kaufmann , A. Lara , J. Lee , H. León Vargas , A. L. Longinotti , G. Luis-Raya , K. Malone , O. Martinez , J. Martínez-Castro , J. A. Matthews , P. Miranda-Romagnoli , J. A. Morales-Soto , E. Moreno , M. Araya , M. Mostafá , M. Najafi , A. Nayerhoda , L. Nellen , N. Omodei , E. Ponce , E. G. Pérez-Pérez , C. D. Rho , D. Rosa-González , M. Roth , H. Salazar , A. Sandoval , M. Schneider , J. Serna-Franco , A. J. Smith , Y. Son , R. W. Springer , O. Tibolla , K. Tollefson , I. Torres , R. Torres-Escobedo , R. Turner , F. Ureña-Mena , E. Varela , L. Villaseñor , X. Wang , Z. Wang , I. J. Watson , H. Wu , S. Yu , S. Yun-Cárcamo , H. Zhou , M. Martin The XMM-Newton collaboration , : , Kaya Mori , Charles J. Hailey , Samar Safi-Harb , Shuo Zhang

Discovery of VHE gamma-rays from the high-frequency-peaked BL Lac object RGB J0152+017

Aims: The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio fluxes. Our aim is to understand the radiative processes by investigating the observed…

Astrophysics · Physics 2008-04-09 HESS Collaboration , F. Aharonian

Powerful high energy emission of the remarkable BL Lac object S5 0716+714

BL Lac objects of the intermediate subclass (IBLs) are known to emit a substantial fraction of their power in the energy range 0.1--10 GeV. Detecting gamma-ray emission from such sources provides therefore a direct probe of the emission…

High Energy Astrophysical Phenomena · Physics 2015-05-14 V. Vittorini , M. Tavani , A. Paggi , A. Cavaliere , A. Bulgarelli , A. W. Chen , F. D'Ammando , I. Donnarumma , A. Giuliani , F. Longo , L. Pacciani , G. Pucella , S. Vercellone , A. Ferrari , S. Colafrancesco , P. Giommi

Exploring the multiband emission of TXS 0536+145: the most distant gamma-ray flaring blazar

We report results of a multiband monitoring campaign of the flat spectrum radio quasar TXS 0536+145 at redshift 2.69. This source was detected during a very high gamma-ray activity state in 2012 March by the Large Area Telescope on board…

High Energy Astrophysical Phenomena · Physics 2015-06-22 M. Orienti , F. D'Ammando , M. Giroletti , J. Finke , M. Ajello , D. Dallacasa , T. Venturi

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

VERITAS Discovery of >200GeV Gamma-ray Emission from the Intermediate-frequency-peaked BL Lac Object W Comae

We report the detection of very high-energy gamma-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae (z=0.102) by VERITAS. The source was observed between January and April 2008. A strong outburst of gamma-ray…

Astrophysics · Physics 2015-05-13 VERITAS Collaboration , V. A. Acciari , E. Aliu , M. Beilicke , W. Benbow , M. Boettcher , S. M. Bradbury , J. H. Buckley , V. Bugaev , Y. Butt , O. Celik , A. Cesarini , L. Ciupik , Y. C. K. Chow , P. Cogan , P. Colin , W. Cui , M. K. Daniel , T. Ergin , A. D. Falcone , S. J. Fegan , J. P. Finley , G. Finnegan , P. Fortin , L. F. Fortson , A. Furniss , D. Gall , G. H. Gillanders , J. Grube , R. Guenette , G. Gyuk , D. Hanna , E. Hays , J. Holder , D. Horan , C. M. Hui , T. B. Humensky , A. Imran , P. Kaaret , N. Karlsson , M. Kertzman , D. B. Kieda , A. Konopelko , H. Krawczynski , F. Krennrich , M. J. Lang , S. LeBohec , K. Lee , G. Maier , A. McCann , M. McCutcheon , P. Moriarty , R. Mukherjee , T. Nagai , J. Niemiec , R. A. Ong , D. Pandel , J. S. Perkins , D. Petry , M. Pohl , J. Quinn , K. Ragan , L. C. Reyes , P. T. Reynolds , E. Roache , H. J. Rose , M. Schroedter , G. H. Sembroski , A. W. Smith , D. Steele , S. P. Swordy , J. A. Toner , V. V. Vassiliev , R. Wagner , S. P. Wakely , J. E. Ward , T. C. Weekes , A. Weinstein , R. J. White , D. A. Williams , S. A. Wissel , M. Wood , B. Zitzer