Test of models of the cosmic infrared background with multiwavelength observations of the blazar 1ES 1218+30.4 in 2009
- Physics Department, McGill University, Montreal, QC H3A 2T8 (Canada)
- Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
- Department of Physics, Washington University, St. Louis, MO 63130 (United States)
- Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, Amado, AZ 85645 (United States)
- School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)
- Department of Physics and Astronomy, Ohio University, Clippinger 339, Athens, OH 45701-2979 (United States)
- Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95064 (United States)
- Astronomy Department, Adler Planetarium and Astronomy Museum, Chicago, IL 60605 (United States)
- School of Physics, National University of Ireland Galway, University Road, Galway (Ireland)
- Department of Physics, Purdue University, West Lafayette, IN 47907 (United States)
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)
- Department of Physics and Astronomy, Barnard College, Columbia University, New York, NY 10027 (United States)
- Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
We present the results of a multi-wavelength campaign targeting the blazar 1ES 1218+30.4 with observations with the 1.3 m McGraw-Hill optical telescope, the Rossi X-ray Timing Explorer (RXTE), the Fermi Gamma-Ray Space Telescope, and the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The RXTE and VERITAS observations were spread over a 13 day period and revealed clear evidence for flux variability, and a strong X-ray and γ-ray flare on 2009 February 26 (MJD 54888). The campaign delivered a well-sampled broadband energy spectrum with simultaneous RXTE and VERITAS very high energy (VHE, >100 GeV) observations, as well as contemporaneous optical and Fermi observations. The 1ES 1218+30.4 broadband energy spectrum—the first with simultaneous X-ray and VHE γ-ray energy spectra—is of particular interest as the source is located at a high cosmological redshift for a VHE source (z = 0.182), leading to strong absorption of VHE gamma rays by photons from the optical/infrared extragalactic background light (EBL) via γ{sub VHE} + γ{sub EBL} → e {sup +} e {sup –} pair-creation processes. We model the data with a one-zone synchrotron self-Compton (SSC) emission model and with the extragalactic absorption predicted by several recent EBL models. We find that the observations are consistent with the SSC scenario and all the EBL models considered in this work. We discuss observational and theoretical avenues to improve on the EBL constraints.
- OSTI ID:
- 22356561
- Journal Information:
- Astrophysical Journal, Vol. 788, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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