Fermi Gamma-ray Space Telescope

Suzaku observation of the Fermi source HESSJ1507-622

Hironori Matsumoto
Y. Babazaki, S. Yoshikawa (Nagoya University), M. Sakai (JAXA), Y. Terada (Saitama Univ.), A. Bamba (Aoyama Gakuin Univ.), O. Tibolla (Wuerzburg University), S. Kaufmann (Heidelberg University)

Abstract:

HESSJ1507-622 is one of the interesting TeV gamma-ray objects. This object is also detected by Fermi. The unique feature is that the location of HESSJ1507 is 3.5 degree away from the Galactic plane. Although most of off-plane TeV objects are active galactic nuclei, HESSJ1507 is slightly extended and so far has no plausible counterpart. Furthermore HESSJ1507 is rather bright (~8% Crab). Two regions of HESSJ1507 was observed with Suzaku in September, 2012, to look for an X-ray counterpart. No X-ray object coincides with the center position of HESSJ1507 was found. Instead, a bright object coincides with 1RXJ150841.2-621006 was detected. This object was also detected by Chandra. This source is not a plausible counterpart, however, since it lies ~15 arcmin away from the center of HESSJ1507. The dim and diffuse object ~5 arcmin away from HESSJ1507 found by Chandra was also confirmed by Suzaku even in a hard X-ray band from 2 to 10 keV. The flux in the 2-10 keV band is 0.8e-13 erg/s/cm2, which is consistent with the Chandra observation. If this object is a counterpart to HESSJ1507, the ratio from the gamma-ray flux to the X-ray flux becomes ~80.