The Astrophysical Journal, 747:104 (17pp), 2012 March 10 doi:10.1088/0004-637X/747/2/104 C 2012. The American Astronomical Society. All rights reserved. Printed in the U.S.A. SEARCH FOR GAMMA-RAY EMISSION FROM X-RAY-SELECTED SEYFERT GALAXIES WITH FERMI-LAT M. Ackermann1, M. Ajello1, A. Allafort1, L. Baldini2, J. Ballet3, G. Barbiellini4,5, D. Bastieri6,7, K. Bechtol1,56, R. Bellazzini2, B. Berenji1, E. D. Bloom1, E. Bonamente8,9, A. W. Borgland1, J. Bregeon2, M. Brigida10,11,P.Bruel12, R. Buehler1, S. Buson6,7, G. A. Caliandro13, R. A. Cameron1, P. A. Caraveo14, J. M. Casandjian3, E. Cavazzuti15, C. Cecchi8,9, E. Charles1, A. Chekhtman16,53, C. C. Cheung17,53, J. Chiang1,S.Ciprini9,18, R. Claus1, J. Cohen-Tanugi19, J. Conrad20,21,54, S. Cutini15, F. D’Ammando22,23, A. de Angelis24, F. de Palma10,11, C. D. Dermer25, E. do Couto e Silva1, P. S. Drell1, A. Drlica-Wagner1,T.Enoto1, C. Favuzzi10,11, S. J. Fegan12, E. C. Ferrara26, P. Fortin12, Y. Fukazawa27, P. Fusco10,11, F. Gargano11, D. Gasparrini15, N. Gehrels26, S. Germani8,9, N. Giglietto10,11, P. Giommi15, F. Giordano10,11, M. Giroletti28, G. Godfrey1, J. E. Grove25, S. Guiriec29, D. Hadasch13, M. Hayashida1,30,56, E. Hays26,R.E.Hughes31, G. Johannesson´ 32,A.S.Johnson1, T. Kamae1, H. Katagiri33, J. Kataoka34,J.Knodlseder¨ 35,36,M.Kuss2,J.Lande1, M. Llena Garde20,21, F. Longo4,5, F. Loparco10,11, B. Lott37, M. N. Lovellette25, P. Lubrano8,9, G. M. Madejski1,56, M. N. Mazziotta11,P.F.Michelson1,T.Mizuno27,C.Monte10,11, M. E. Monzani1, A. Morselli38, I. V. Moskalenko1, S. Murgia1,S.Nishino27, J. P. Norris39,E.Nuss19, M. Ohno40,T.Ohsugi41, A. Okumura1,40, E. Orlando1,42, M. Ozaki40, D. Paneque1,43, M. Pesce-Rollins2, M. Pierbattista3,F.Piron19, G. Pivato7, T. A. Porter1,S.Raino` 10,11, R. Rando6,7, M. Razzano2,44,A.Reimer1,45,O.Reimer1,45,S.Ritz44, M. Roth46, D. A. Sanchez47, C. Sbarra6,C.Sgro` 2,E.J.Siskind48, G. Spandre2, P. Spinelli10,11, Ł. Stawarz40,49,56, A. W. Strong42, H. Takahashi41, T. Takahashi40, T. Tanaka1, J. B. Thayer1, D. J. Thompson26, L. Tibaldo6,7, M. Tinivella2, D. F. Torres13,50,G.Tosti8,9,E.Troja26,55, Y. Uchiyama1, T. L. Usher1, J. Vandenbroucke1, V. Vasileiou19, G. Vianello1,51, V. Vitale38,52,A.P.Waite1,B.L.Winer31, K. S. Wood25, M. Wood1,Z.Yang20,21, and S. Zimmer20,21 1 W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305, USA; [email protected], [email protected], [email protected] 2 Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, Italy 3 Laboratoire AIM, CEA-IRFU/CNRS/Universite´ Paris Diderot, Service d’Astrophysique, CEA Saclay, F-91191 Gif sur Yvette, France 4 Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste, Italy 5 Dipartimento di Fisica, Universita` di Trieste, I-34127 Trieste, Italy 6 Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova, Italy 7 Dipartimento di Fisica “G. Galilei,” Universita` di Padova, I-35131 Padova, Italy 8 Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia, Italy 9 Dipartimento di Fisica, Universita` degli Studi di Perugia, I-06123 Perugia, Italy 10 Dipartimento di Fisica “M. Merlin” dell’Universita` e del Politecnico di Bari, I-70126 Bari, Italy 11 Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, Italy 12 Laboratoire Leprince-Ringuet, Ecole´ polytechnique, CNRS/IN2P3,F-91128 Palaiseau, France 13 Institut de Ciencies` de l’Espai (IEEE-CSIC), Campus UAB, E-08193 Barcelona, Spain 14 INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-20133 Milano, Italy 15 Agenzia Spaziale Italiana (ASI) Science Data Center, I-00044 Frascati (Roma), Italy 16 Artep Inc., 2922 Excelsior Springs Court, Ellicott City, MD 21042, USA 17 National Research Council Research Associate, National Academy of Sciences, Washington, DC 20001, USA 18 ASI Science Data Center, I-00044 Frascati (Roma), Italy 19 Laboratoire Univers et Particules de Montpellier, Universite´ Montpellier 2, CNRS/IN2P3, F-34095 Montpellier, France 20 Department of Physics, Stockholm University, AlbaNova, SE-106 91 Stockholm, Sweden 21 The Oskar Klein Centre for Cosmoparticle Physics, AlbaNova, SE-106 91 Stockholm, Sweden 22 IASF Palermo, I-90146 Palermo, Italy 23 INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, I-00133 Roma, Italy 24 Dipartimento di Fisica, Universita` di Udine and Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, Gruppo Collegato di Udine, I-33100 Udine, Italy 25 Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352, USA 26 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA 27 Department of Physical Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan 28 INAF Istituto di Radioastronomia, I-40129 Bologna, Italy 29 Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899, USA 30 Department of Astronomy, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan 31 Department of Physics, Center for Cosmology and Astro-Particle Physics, The Ohio State University, Columbus, OH 43210, USA 32 Science Institute, University of Iceland, IS-107 Reykjavik, Iceland 33 College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito 310-8512, Japan 34 Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, Japan 35 CNRS, IRAP, F-31028 Toulouse cedex 4, France 36 GAHEC, Universite´ de Toulouse, UPS-OMP, IRAP, F-31100 Toulouse, France 37 CNRS/IN2p3, Centre d’Etudes´ Nucleaires´ de Bordeaux Gradignan, Universite´ Bordeaux 1, F-33175 Gradignan, France 38 Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata,” I-00133 Roma, Italy 39 Department of Physics, Boise State University, Boise, ID 83725, USA 40 Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210, Japan; [email protected] 41 Hiroshima Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan 42 Max-Planck Institut fur¨ extraterrestrische Physik, D-85748 Garching, Germany 43 Max-Planck-Institut fur¨ Physik, D-80805 Munchen,¨ Germany 44 Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064, USA 45 Institut fur¨ Astro- und Teilchenphysik and Institut fur¨ Theoretische Physik, Leopold-Franzens-Universitat¨ Innsbruck, A-6020 Innsbruck, Austria 46 Department of Physics, University of Washington, Seattle, WA 98195-1560, USA 1 The Astrophysical Journal, 747:104 (17pp), 2012 March 10 Ackermann et al. 47 Max-Planck-Institut fur¨ Kernphysik, D-69029 Heidelberg, Germany 48 NYCB Real-Time Computing Inc., Lattingtown, NY 11560-1025, USA 49 Astronomical Observatory, Jagiellonian University, 30-244 Krakow,´ Poland 50 Institucio´ Catalana de Recerca i Estudis Avan¸cats (ICREA), E-08010 Barcelona, Spain 51 Consorzio Interuniversitario per la Fisica Spaziale (CIFS), I-10133 Torino, Italy 52 Dipartimento di Fisica, Universita` di Roma “Tor Vergata,” I-00133 Roma, Italy Received 2011 September 20; accepted 2011 December 12; published 2012 February 22 ABSTRACT We report on a systematic investigation of the γ -ray properties of 120 hard X-ray-selected Seyfert galaxies classified as “radio-quiet” objects, utilizing the three-year accumulation of Fermi Large Area Telescope (LAT) data. Our sample of Seyfert galaxies is selected using the Swift Burst Alert Telescope 58 month catalog, restricting −11 −2 −1 the analysis to the bright sources with average hard X-ray fluxes F14−195 keV 2.5 × 10 erg cm s at high Galactic latitudes (|b| > 10◦). In order to remove “radio-loud” objects from the sample, we use the “hard X-ray radio loudness parameter,” RrX, defined as the ratio of the total 1.4 GHz radio to 14–195 keV hard X-ray energy −4 fluxes. Among 120 X-ray bright Seyfert galaxies with RrX < 10 , we did not find a statistically significant γ -ray excess (TS > 25) positionally coincident with any target Seyferts, with possible exceptions of ESO 323–G077 and NGC 6814. The mean value of the 95% confidence level γ -ray upper limit for the integrated photon flux above 100 MeV from the analyzed Seyferts is 4 × 10−9 photons cm−2 s−1 , and the upper limits derived for several objects reach 1 × 10−9 photons cm−2 s−1 . Our results indicate that no prominent γ -ray emission component related to active galactic nucleus activity is present in the spectra of Seyferts around GeV energies. The Fermi-LAT upper limits derived for our sample probe the ratio of γ -ray to X-ray luminosities Lγ /LX < 0.1, and even <0.01 in some cases. The obtained results impose novel constraints on the models for high-energy radiation of “radio-quiet” Seyfert galaxies. Key words: accretion, accretion disks – galaxies: active – galaxies: Seyfert – gamma rays: galaxies – X-rays: galaxies Online-only material: color figures 1. INTRODUCTION galactic centers and are powered by the infalling matter which forms accretion disks emitting intense optical/UV continuum The all-sky observations of celestial objects by the Large Area radiation. Telescope (LAT; Atwood et al. 2009) aboard the Fermi Gamma- Seyfert galaxies are generally much weaker radio emitters ray Space Telescope confirmed that, in addition to gamma-ray than radio quasars or radio galaxies, but they are not “radio bursts, there are at least two more general classes of bright ex- silent.” In addition to the diffuse radio continuum originating in tragalactic sources of γ -rays (Abdo et al. 2010b). One class the ISM of their late-type hosts, about half of the nearby Seyferts comprises active galactic nuclei (AGNs) with powerful rela- possess compact non-thermal radio cores (Ulvestad & Wilson tivistic jets, including blazars, radio-loud Narrow-line Seyfert 1989; Kukula et al.