Fermi/LAT Discovery of Gamma-Ray Emission From the Flat-Spectrum Radio Quasar PKS 1454-354.

摘要

We report the discovery by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope of high-energy ?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?6 ph cm?2 s?1 (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.