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We have analyzed all the archival X-ray data of 134 unidentified (unID)gammaray sources listed in the first Fermi/LAT (1FGL) catalog and subsequentlyfollowed up by Swift/XRT. We constructed the spectral energy distributions(SEDs) from radio to gamma-rays for each X-ray source detected, and tried topick up unique objects that display anomalous spectral signatures. In theseanalysis, we target all the 1FGL unID sources, using updated data from thesecond Fermi/LAT (2FGL) catalog on their LAT position and spectra. We foundseveral potentially interesting objects, particularly three sources, 1FGLJ0022.2-1850, 1FGL J0038.0+1236 and 1FGL J0157.0-5259, which were then moredeeply observed with Suzaku as a part of an AO7 program in 2012. Wesuccessfully detected an X-ray counterpart for each source whose X-ray spectrawere well fitted by a single power-law function. The positional coincidencewith a bright radio counterpart (currently identified as AGN) in the 2FGL errorcircles suggests these are definitely the X-ray emission from the same AGN, buttheir SEDs show a wide variety of behavior. In particular, the SED of 1FGLJ0038.0+1236 is difficult to be explained by conventional emission models ofblazars. The source 1FGL J0022.2-1850 may be in a transition state between alow-frequency peaked BL Lac and a high-frequency peaked BL Lac object, and 1FGLJ0157.0-5259 could be a rare kind of extreme blazar. We discuss the possiblenature of these three sources observed with Suzaku, together with the X-rayidentification results and SEDs of all 134 sources observed with Swift/XRT.

Multiband Diagnostics of Unidentified 1FGL Sources with Suzaku and Swift X-ray Observations