Cross Spectral Calibration of Suzaku, XMM-Newton, and Chandra with PKS 2155-304 as an Activity of IACHEC

We report on comparisons of the energy responses of the Suzaku XIS, the Chandra HRC and ACIS with the LETG, and the XMM-Newton MOS and pn using simultaneous data of the BL Lac object PKS 2155 304 taken in 2005, 2006, and 2008. From power-law fits to individual spectra, we have found that the photon index agrees among all instruments within ' 0.1, and that the resultant hydrogen column density values of the Chandra and XMM-Newton instruments differ from the value for PKS 2155 304 only by .1 10 cm , while that of Suzaku bears a larger systematic error of 4 10 cm , at most. We have carried out flux cross-calibration in seven small segments of energy bands between 0.5 keV and 10 keV. In the bands above 2 keV, the Suzaku fluxes are larger than those of XMM-Newton by ' 20%, ' 10%, and . 5% in 2005, 2006, and 2008, respectively, although the 20% difference in 2005 is still preliminary. The fluxes of the LETG+HRC in 2006 coincide with those of Suzaku below 2 keV. The fluxes of the LETG+ACIS are compared with those of Suzaku and XMM-Newton with the 2008 data, and are systematically larger than those of Suzaku and XMM-Newton by 10%. These results are in general consistent with those presented in one of the precedent papers from International Astronomical Consortium for High Energy Calibration (IACHEC) using G21.5 0.9.