Global distribution of ionizing and recombining plasmas in the supernova remnant G290.1-0.8

We report on the Suzaku results of the mixed-morphology supernova remnant (SNR) G290.1-0.8 (MSH 11-61A). The SNR has an asymmetric structure extended to the south-east and the north-west. In the X-ray spectra of the center and the north-west regions, we discover recombining plasma features with a strong Si Lyα and radiative recombination continuum at ∼ 2.7 keV. These features are the most significant in the north-west region, and the spectra are well reproduced with a recombining plasma of kT_e = 0.5 keV, whereas the spectra of other regions are expressed by an ionizing plasma of kT_e = 0.6 keV. The recombining plasma has over-solar abundances, while the ionizing plasma has roughly solar abundances. Hence they are likely ejecta and of interstellar medium (ISM) origin, respectively. The recombining plasma in the north-west of G290.1-0.8 would be generated by a break-out of the supernova ejecta from a high density circumstellar medium to a low density ISM.