| Autor: |
Archambault, S, Aune, T, Behera, B, Beilicke, M, Benbow, W, Berger, K, Bird, R, Biteau, J, Bugaev, V, Byrum, K, Cardenzana, JV, Cerruti, M, Chen, X, Ciupik, L, Connolly, MP, Cui, W, Dumm, J, Errando, M, Falcone, A, Federici, S, Feng, Q, Finley, JP, Fleischhack, H, Fortson, L, Furniss, A, Galante, N, Gillanders, GH, Griffin, S, Griffiths, ST, Grube, J, Gyuk, G, Hanna, D, Holder, J, Hughes, G, Humensky, TB, Johnson, CA, Kaaret, P, Kertzman, M, Khassen, Y, Kieda, D, Krawczynski, H, Krennrich, F, Kumar, S, Lang, MJ, Madhavan, AS, Maier, G, McCann, A, Meagher, K, Moriarty, P, Mukherjee, R, Nieto, D, De Bhróithe, AOF, Ong, RA, Otte, AN, Park, N, Pohl, M, Popkow, A, Prokoph, H, Quinn, J, Ragan, K, Rajotte, J, Reyes, LC, Reynolds, PT, Richards, GT, Roache, E, Sembroski, GH, Shahinyan, K, Staszak, D, Telezhinsky, I, Tucci, JV, Tyler, J, Varlotta, A, Vassiliev, VV, Vincent, S, Wakely, SP, Weinstein, A, Welsing, R, Wilhelm, A, Williams, DA, Ackermann, M, Ajello, M, Albert, A, Baldini, L, Bastieri, D, Bellazzini, R, Bissaldi, E, Bregeon, J, Buehler, R, Buson, S, Caliandro, GA, Cameron, RA, Caraveo, PA |
| Jazyk: |
angličtina |
| Rok vydání: |
2014 |
| Předmět: |
|
| Zdroj: |
Archambault, S; Aune, T; Behera, B; Beilicke, M; Benbow, W; Berger, K; et al.(2014). Deep broadband observations of the distant gamma-ray blazar PKS 1424+240. Astrophysical Journal Letters, 785(1). doi: 10.1088/2041-8205/785/1/L16. UC Irvine: Retrieved from: http://www.escholarship.org/uc/item/02c2w6nz |
| Popis: |
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) × 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) × 10-7 photons m-2 s-1 above 120 GeV. The measured differential very high energy (VHE; E ≥ 100 GeV) spectral indices are Γ = 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 τ = 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. © 2014. The American Astronomical Society. All rights reserved.. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
|
