アブストラクト：
We report a study of X-ray irradiated ISM in Circinus galaxy using Chandra and ALMA 20 pc resolution data. We spatially compare X-ray irradiated gas traced by the 6.4 keV iron-Kalpha line and molecular gas. A noticeable finding is that within an iron line bright area, the molecular line emission is suppressed. We quantitatively discuss this in accordance with the XDR model, and estimate an effective ionization parameter. At R = 60 pc from the nucleus, corresponding to a limb of the iron line bright region, the parameter is consistent with a predicted hydrogen atomic-to-molecular gas transition boundary (Maloney 1996). This supports that the X-ray radiation dissociates the molecular gas.