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The 2009 Fermi Symposium

Swift Monitoring of Fermi Blazars

Abe D. Falcone


Since September of 2008, we have obtained weekly multiwavelength monitoring data, specifically Swift (XRT, UVOT, BAT) data, on the 23 “sources of interest” that have been monitored by Fermi and publicly released in the form of light curves and spectra. These sources are comprised of 22 blazars and one TeV emihng X-ray binary system. We have also obtained contemporaneous Swift data during gamma-ray high states (originally defined by the Fermi-LAT team as flux > 2 x 10-6 photons cm-2 s-1 from these sources and from several other new sources that exceeded this threshold. The reduced Swift-XRT (0.2-10 keV) data products are being released publicly at These data allow us to study the broad band spectrum of blazars from the synchrotron component through the high energy component, which could be due to a variety of leptonic inverse Compton mechanisms or hadronic mechanisms with varying magnitude depending on jet dynamics and environment. These data have allowed the study of some objects never before measured in gamma-ray high states, as well as the more detailed study of historically active blazars. These studies facilitate the further study of the blazar sequence and evolution, as well as the study of the cosmic infrared background using blazars as back illuminators. We will report on the status of this long-term and ongoing observation campaign and provide the initial results.