Fermi /lat Discovery of Gamma-ray Emission from the Flat-spectrum Radio Quasar Pks 1454-354
نویسندگان
چکیده
We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope of high-energy γ−ray (GeV) emission from the flat-spectrum radio quasar PKS 1454-354 (z = 1.424). On 4 September 2008 the source rose to a peak flux of (3.5±0.7)×10 ph cm s (E > 100 MeV) on a time scale of hours and then slowly dropped over the following two days. No significant spectral changes occurred during the flare. Fermi/LAT observations also showed that PKS 1454-354 is the most probable counterpart of the unidentified EGRET source 3EG J1500−3509. Multiwavelength measurements performed during the following days (7 September with Swift ; 6−7 September with the ground-based optical telescope ATOM ; 13 September with the Australia Telescope Compact Array) resulted in radio, optical, UV and X-ray fluxes greater than archival data, confirming the activity of PKS 1454-354. Subject headings: quasars: individual (PKS 1454-354) – galaxies: active – gamma rays: observations * Corresponding author: L. Foschini, [email protected] 1 National Research Council Research Associate 2 Space Science Division, Naval Research Laboratory, Washington, DC 20375 3 W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Laboratory, Stanford University, Stanford, CA 94305 4 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 5 The Oskar Klein Centre for Cosmo Particle Physics, AlbaNova, SE-106 91 Stockholm, Sweden 6 Department of Astronomy, Stockholm University, SE-106 91 Stockholm, Sweden 7 Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa, Italy 8 Laboratoire AIM, CEA-IRFU/CNRS/Université Paris Diderot, Service d’Astrophysique, CEA Saclay, 91191 Gif sur Yvette, France 9 Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste, Italy 10 Dipartimento di Fisica, Università di Trieste, I-34127 Trieste, Italy 11 Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova, Italy 12 Dipartimento di Fisica “G. Galilei”, Università di Padova, SLAC-PUB-13619
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