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Journal article
Deep broadband observations of the distant gamma-ray blazar pks 1424+240
The Astrophysical Journal
28 Mar 2014
Abstract
We present deep VERITAS observations of the blazar PKS 1424+240, along with contemporaneous Fermi Large Area Telescope, Swift X-ray Telescope, and Swift UV Optical Telescope data between 2009 February 19 and 2013 June 8. This blazar resides at a redshift of z >= 0.6035, displaying a significantly attenuated gamma-ray flux above 100 GeV due to photon absorption via pair-production with the extragalactic background light. We present more than 100 hr of VERITAS observations over three years, a multiwavelength light curve, and the contemporaneous spectral energy distributions. The source shows a higher flux of (2.1 +/- 0.3) x 10(-7) photons m(-2) s(-1) above 120 GeV in 2009 and 2011 as compared to the flux measured in 2013, corresponding to (1.02 +/- 0.08) x 10-7 photons m(-2) s(-1) above 120 GeV. The measured differential very high energy (VHE; E >= 100 GeV) spectral indices are Gamma = 3.8 +/- 0.3, 4.3 +/- 0.6 and 4.5 +/- 0.2 in 2009, 2011, and 2013, respectively. No significant spectral change across the observation epochs is detected. We find no evidence for variability at gamma-ray opacities of greater than tau = 2, where it is postulated that any variability would be small and occur on timescales longer than a year if hadronic cosmic-ray interactions with extragalactic photon fields provide a secondary VHE photon flux. The data cannot rule out such variability due to low statistics.
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19 citations in Scopus
Details
- Title
- Deep broadband observations of the distant gamma-ray blazar pks 1424+240
- Creators
- S Archambault - McGill UniversityT Aune - University of California, Los AngelesB BeheraM Beilicke - Washington University in St. LouisW Benbow - Harvard UniversityK Berger - University of DelawareR Bird - University College DublinJ Biteau - University of California, Santa CruzV Bugaev - Washington University in St. LouisK Byrum - Argonne National LaboratoryJ. V Cardenzana - Iowa State UniversityM Cerruti - Harvard UniversityX Chen - University of PotsdamL Ciupik - Adler PlanetariumM. P Connolly - National University of Ireland, GalwayW Cui - Purdue University West LafayetteJ Dumm - University of MinnesotaM Errando - Columbia UniversityA Falcone - Pennsylvania State UniversityS Federici - University of PotsdamQ Feng - Purdue University West LafayetteJ. P Finley - Purdue University West LafayetteH FleischhackL Fortson - University of MinnesotaA Furniss - Stanford UniversityN Galante - Harvard UniversityG. H Gillanders - National University of Ireland, GalwayS Griffin - McGill UniversityS. T Griffiths - University of IowaJ Grube - Adler PlanetariumG Gyuk - Adler PlanetariumD Hanna - McGill UniversityJ Holder - University of DelawareG HughesT. B Humensky - Columbia UniversityC. A Johnson - University of California, Santa CruzP Kaaret - University of IowaM Kertzman - DePauw UniversityY Khassen - University College DublinD Kieda - University of UtahH Krawczynski - Washington University in St. LouisF Krennrich - Iowa State UniversityS Kumar - University of DelawareM. J Lang - National University of Ireland, GalwayA. S Madhavan - Iowa State UniversityG MaierA McCann - University of ChicagoK Meagher - Georgia Institute of TechnologyP Moriarty - Galway-Mayo Institute of TechnologyR Mukherjee - Columbia UniversityD Nieto - Columbia UniversityA. O'Faoláin de Bhróithe - University College DublinR. A Ong - University of California, Los AngelesA. N Otte - Georgia Institute of TechnologyN Park - University of ChicagoM Pohl - University of PotsdamA Popkow - University of California, Los AngelesH ProkophJ Quinn - University College DublinK Ragan - McGill UniversityJ Rajotte - McGill UniversityL. C Reyes - California Polytechnic State UniversityP. T Reynolds - Cork Institute of TechnologyG. T Richards - Georgia Institute of TechnologyE Roache - Harvard UniversityG. H Sembroski - Purdue University West LafayetteK Shahinyan - University of MinnesotaD Staszak - McGill UniversityI Telezhinsky - University of PotsdamJ. V Tucci - Purdue University West LafayetteJ Tyler - McGill UniversityA Varlotta - Purdue University West LafayetteV. V Vassiliev - University of California, Los AngelesS VincentS. P Wakely - University of ChicagoA WeinsteinR WelsingA Wilhelm - University of PotsdamD. A Williams - University of California, Santa CruzM AckermannM Ajello - University of California, BerkeleyA Albert - Stanford UniversityL Baldini - National Institute for Nuclear PhysicsD Bastieri - University of PaduaR Bellazzini - National Institute for Nuclear PhysicsE Bissaldi - University of TriesteJ BregeonR BuehlerS Buson - University of PaduaG. A CaliandroR. A Cameron - Stanford UniversityP. A Caraveo - National Institute for AstrophysicsE CavazzutiE Charles - Stanford UniversityJ Chiang - Stanford UniversityS CipriniR Claus - Stanford UniversityS CutiniF D'Ammando - National Institute for AstrophysicsA de Angelis - National Institute for Nuclear PhysicsF de Palma - Instituto Politécnico NacionalC. D Dermer - United States Naval Research LaboratoryS. W Digel - Stanford UniversityL Di Venere - University of Bari Aldo MoroP. S Drell - Stanford UniversityC Favuzzi - Instituto Politécnico NacionalA Franckowiak - Stanford UniversityP Fusco - Instituto Politécnico NacionalF Gargano - National Institute for Nuclear PhysicsD GasparriniN Giglietto - Instituto Politécnico NacionalF Giordano - Instituto Politécnico NacionalM GirolettiI. A GrenierS GuiriecT Jogler - Stanford UniversityM Kuss - National Institute for Nuclear PhysicsS Larsson - Stockholm UniversityL Latronico - National Institute for Nuclear PhysicsF Longo - University of TriesteF Loparco - Instituto Politécnico NacionalP Lubrano - University of PerugiaG. M Madejski - Stanford UniversityM MayerM. N Mazziotta - National Institute for Nuclear PhysicsP. F Michelson - Stanford UniversityT Mizuno - Hiroshima UniversityM. E Monzani - Stanford UniversityA Morselli - National Institute for Nuclear PhysicsS Murgia - University of California, IrvineE NussT Ohsugi - Hiroshima UniversityJ. F Ormes - University of DenverD Paneque - Max Planck SocietyJ. S Perkins - Goddard Space Flight CenterF PironG Pivato - University of PaduaS Rainò - Instituto Politécnico NacionalM RazzanoA ReimerO Reimer - Innsbruck Medical UniversityS Ritz - University of California, Santa CruzM Schaal - United States Naval Research LaboratoryC Sgrò - National Institute for Nuclear PhysicsE. J SiskindP Spinelli - Instituto Politécnico NacionalH Takahashi - Hiroshima UniversityL Tibaldo - Stanford UniversityM Tinivella - National Institute for Nuclear PhysicsE Troja - University of Maryland, College ParkG Vianello - Stanford UniversityM Werner - Innsbruck Medical UniversityM Wood - Stanford University
- Publication Details
- The Astrophysical Journal
- Publisher
- IOP Publishing
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Physics
- Scopus ID
- 2-s2.0-84897391193
- Other Identifier
- 991019201369204721