Deep Broadband Observations of the Distant Gamma-ray Blazar PKS 1424+240

Archambault, S.; Aune T.; Behera B.; Beilicke M.; Benbow W.; Berger K.; Bird R.; Biteau J.; Bugaev V.; Byrum K.; Cardenzana J. V; Cerruti M.; Chen X.; Ciupik L.; Connolly M. P.; Cui W.; Dumm J.; Errando M.; Falcone A.; Federici S.; Feng Q.;; de Bhróithe, A. O'Faoláin; de Angelis, A.; de Palma, F.; Aune, T.; Behera, B.; Beilicke, M.; Benbow, W.; Berger, K.; Bird, R.; Biteau, J.; Jv, Cardenzana; Bugaev, V.; Byrum, K.; Cardenzana, J. V.; Cerruti, M.; Mp, Connolly; Chen, X.; Ciupik, L.; Connolly, M.~P P.; Cui, W.; Dumm, J.; Jp, Finley; Errando, M.; Falcone, A.; Federici, S.; Feng, Q.; Gh, Gillanders; Finley, J.~P P.; Fleischhack, H.; Fortson, L.; Furniss, A.; Galante, N.; Gillanders, G.~H H.; St, Griffiths; Griffin, S.; Griffiths, S.~T T.; Grube, J.; Gyuk, G.; Hanna, D.; Holder, J.; Tb, Humensky; Hughes, G.; Ca, Johnson; Humensky, T.~B B.; Johnson, C.~A A.; Kaaret, P.; Kertzman, M.; Khassen, Y.; Kieda, D.; Krawczynski, H.; Mj, Lang; Krennrich, F.; Kumar, S.; As, Madhavan; Lang, M.~J J.; Madhavan, A.~S S.; Maier, G.; McCann, A.; Meagher, K.; Moriarty, P.; Mukherjee, R.; O'Faolain de Bhroithe, A.; Nieto, D.; Ao, de Bhroithe; De Bhróithe, A. O.; Ong, R.~A A.; Ra, Ong; Otte, A.~N N.; An, Otte; Park, N.; Pohl, M.; Popkow, A.; Prokoph, H.; Quinn, J.; Ragan, K.; Rajotte, J.; Reyes, L.~C C.; Lc, Reyes; Reynolds, P.~T T.; Pt, Reynolds; Richards, G.~T T.; Roache, E.; Sembroski, G.~H H.; Gt, Richards; Shahinyan, K.; Staszak, D.; Gh, Sembroski; Telezhinsky, I.; Tucci, J. V.; Tyler, J.; Varlotta, A.; Jv, Tucci; Vassiliev, V. V.; Vincent, S.; Wakely, S.~P P.; Weinstein, A.; Vv, Vassiliev; Welsing, R.; Wilhelm, A.; Williams, D.~A A.; Sp, Wakely; Ackermann, M.; Ajello, M.; Albert, A.; Da, Williams; Baldini, L.; Bastieri, D.; Bellazzini, R.; Bissaldi, E.; Bregeon, J.; Buehler, R.; Buson, S.; Caliandro, G.~A A.; Cameron, R.~A A.; Caraveo, P.~A A.; Ga, Caliandro; Cavazzuti, E.; Charles, E.; Chiang, J.; Ra, Cameron; Ciprini, S.; Veritas, Collaboration; Claus, R.; Pa, Caraveo; Cutini, S.; D'Ammando, F.; Dermer, C.~D D.; Cd, Dermer; Digel, S.~W W.; Sw, Digel; Di Venere, L.; Drell, P.~S S.; Favuzzi, C.; Ps, Drell; Franckowiak, A.; Fusco, P.; Gargano, F.; Gasparrini, D.; Giglietto, N.; Giordano, Francesca; Giroletti, M.; Grenier, I.~A A.; Ia, Grenier; Guiriec, S.; Jogler, T.; Kuss, M.; Larsson, S.; Latronico, L.; Longo, F.; Loparco, F.; Lubrano, P.; Madejski, G.~M M.; Gm, Madejski; Mayer, M.; Mazziotta, M.~N N.; Michelson, P.~F F.; Mn, Mazziotta; Mizuno, T.; Pf, Michelson; Monzani, M.~E E.; Morselli, A.; Me, Monzani; Murgia, S.; Nuss, E.; Ohsugi, T.; Ormes, J.~F F.; Paneque, D.; Perkins, J.~S S.; Jf, Ormes; Piron, F.; Pivato, G.; Js, Perkins; Raino, S.; Razzano, M.; Reimer, A.; Reimer, O.; Ritz, S.; Schaal, M.; Sgro, C.; Siskind, E.~J J.; Ej, Siskind; Spinelli, P.; Takahashi, H.; Tibaldo, L.; Tinivella, M.; Troja, E.; Vianello, G.; Werner, M.; Wood, M.; Collaboration, Fermi Lat

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American Astronomical Society, Astrophysical Journal Letters, 1(785), p. L16, 2014

DOI: 10.1088/2041-8205/785/1/l16

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Deep Broadband Observations of the Distant Gamma-ray Blazar PKS 1424+240

Journal article published in 2014 by S.; Aune T.; Behera B.; Beilicke M.; Benbow W.; Berger K.; Bird R.; Biteau J.; Bugaev V.; Byrum K.; Cardenzana J. V; Cerruti M.; Chen X.; Ciupik L.; Connolly M. P.; Cui W.; Dumm J.; Errando M.; Falcone A.; Federici S.; Feng Q.; Archambault, A. O'Faoláin de Bhróithe

, A. de Angelis, F. de Palma, T. Aune, B. Behera

, M. Beilicke, W. Benbow

, K. Berger

, R. Bird

, J. Biteau

, Cardenzana Jv, V. Bugaev, K. Byrum, J. V. Cardenzana

and other authors.

This paper is made freely available by the publisher.

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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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Deep Broadband Observations of the Distant Gamma-ray Blazar PKS 1424+240

Abstract