We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGNs), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma-rays from an AGN interact with extragalactic background light (EBL) photons to produce electron-positron pairs, which then interact with cosmic microwave background photons via inverse-Compton scattering to produce gamma-rays. Due to the deflection of the electron-positron pairs, a non-zero intergalactic magnetic field (IGMF) would potentially produce detectable effects on the angular distribution of the cascade emission. In particular, an angular broadening compared to the unscattered emission could occur. Through non-detection of angularly broadened emission from 1ES 1218+304, the source with the largest predicted cascade fraction, we exclude a range of IGMF strengths around 10 -14 G at the 95% confidence level. The extent of the exclusion range varies with the assumptions made about the intrinsic spectrum of 1ES 1218+304 and the EBL model used in the simulation of the cascade process. All of the sources are used to set limits on the flux due to extended emission. © 2017. The American Astronomical Society. All rights reserved..
Documento: | Artículo |
Título: | Search for Magnetically Broadened Cascade Emission from Blazars with VERITAS |
Autor: | Archambault, S.; Archer, A.; Benbow, W.; Buchovecky, M.; Bugaev, V.; Cerruti, M.; Connolly, M.P.; Cui, W.; Falcone, A.; Alonso, M.F.; Finley, J.P.; Fleischhack, H.; Fortson, L.; Furniss, A.; Griffin, S.; Hütten, M.; Hervet, O.; Holder, J.; Humensky, T.B.; Johnson, C.A.; Kaaret, P.; Kar, P.; Kieda, D.; Krause, M.; Krennrich, F.; Lang, M.J.; Lin, T.T.Y.; Maier, G.; McArthur, S.; Moriarty, P.; Nieto, D.; O'Brien, S.; Ong, R.A.; Otte, A.N.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P.T.; Richards, G.T.; Roache, E.; Rovero, A.C.; Sadeh, I.; Shahinyan, K.; Staszak, D.; Telezhinsky, I.; Tyler, J.; Wakely, S.P.; Weinstein, A.; Weisgarber, T.; Wilcox, P.; Wilhelm, A.; Williams, D.A.; Zitzer, B. |
Filiación: | Physics Department, McGill University, Montreal, QC H3A 2T8, Canada 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 Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, United States School of Physics, National University of Ireland Galway, University Road, Galway, Ireland Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, United States Department of Physics, Center for Astrophysics, Tsinghua University, Beijing, 100084, China Department of Astronomy and Astrophysics, 525 Davey Lab, Pennsylvania State University, University Park, PA 16802, United States Instituto de Astronomia y Fisica Del Espacio (IAFE CONICET-UBA), CC 67 - Suc. 28, Ciudad Autónoma de Buenos Aires, C1428ZAA, Argentina DESY, Platanenallee 6, Zeuthen, D-15738, Germany School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, United States Department of Physics, California State University, East Bay, Hayward, CA 94542, United States Santa Cruz Institute for Particle Physics, Department of Physics, University of California, Santa Cruz, CA 95064, United States Department of Physics and Astronomy, Bartol Research Institute, University of Delaware, Newark, DE 19716, United States Physics Department, Columbia University, New York, NY 10027, United States Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242, United States Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, United States Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, United States School of Physics, University College Dublin, Belfield, Dublin 4, Ireland School of Physics and Center for Relativistic Astrophysics, Georgia Institute of Technology, 837 State Street NW, Atlanta, GA 30332-0430, United States Institute of Physics and Astronomy, University of Potsdam, Potsdam-Golm, D-14476, Germany Department of Physical Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, United States Department of Physics, University of Wisconsin-Madison, Madison, WI 53706, United States |
Palabras clave: | BL Lacertae objects: general; galaxies: active; gamma rays: galaxies; magnetic fields |
Año: | 2017 |
Volumen: | 835 |
Número: | 2 |
DOI: | http://dx.doi.org/10.3847/1538-4357/835/2/288 |
Título revista: | Astrophysical Journal |
Título revista abreviado: | Astrophys. J. |
ISSN: | 0004637X |
Registro: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v835_n2_p_Archambault |