Cross spectral calibration of Suzaku, XMM-Newton, and Chandra with PKS 2155-304 as an activity of IACHEC

Abstract

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 ∼l1 × 1020 cm -2, while that of Suzaku bears a larger systematic error of 4 × 1020 cm-2, 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 ∼l5% 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 comparedwith 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. © 2011. Astronomical Society of Japan.