ALMA CO Observations toward the Magellanic Supernova Remnants

The Large Magellanic Cloud (LMC) is among the best laboratories for studying various astronomical objects and their physics because of its almost face-on inclination to us, and a well-known distance (~50 kpc). Supernova remnants (SNRs) in the LMC were well studied by radio continuum, optical, and X-ray observations (e.g., Bozzetto et al. 2017 and references therein). By contrast, very few attempts have been made to observe molecular clouds associated with the LMC SNRs (Banas et al. 1998). Sano et al. (2017a,b) observed 25 X-ray bright LMC SNRs using the Mopra 22-m and ASTE 10-m radio telescopes with a spatial resolution of ~6-11 pc. At least twelve of them were shown to have giant molecular clouds that have a good spatial correspondence with X-ray shells; this indicates that shock-cloud interactions may have occurred. Subsequently, we observed five SNRs N132D, N49, N103B, N63A, and 30 Doradus C using the Atacama Large Millimeter / submillimeter Array (ALMA) with a spatial resolution of ~0.4-0.7 pc during Cycles 2, 3, and 5. We spatially resolved clumpy molecular clouds associated with the LMC SNRs for the first time (Yamane et al. 2018; Sano et al. 2018, 2019). We are therefore entering a new age in studying the Magellanic SNRs yielding a spatial resolution comparable to what had been possible only for Milky Way SNRs. For N49, the synchrotron radio emission is clearly enhanced around molecular clouds, suggesting that the magnetic field amplification occurred via shock-cloud interactions (Yamane, Sano et al. 2019). For the Type Ia SNR N103B, molecular clouds nicely trace the X-ray shell boundary, which shows an expanding gas motion in the position-velocity diagram with an expansion velocity of ~5 km/s. The expanding gas motion was possibly created by accretion winds from a single- degenerate progenitor system (Sano et al. 2018). For N63A, we spatially resolved clumpy molecular clouds embedded within both the shock-ionized and photoionized optic al nebulae, indicating that the molecular clouds have started to be ionized by shock waves and UV- radiation (Sano et al. 2019). In this talk, we report our latest results of CO studies in the X-ray bright LMC SNRs using ALMA