N132D is the brightest gamma-ray supernova remnant (SNR) in the Large Magellanic Cloud (LMC). We carried out $^{12}$CO($J$ = 1-0, 3-2) observations toward the SNR using the Atacama Large Millimeter/submillimeter Array (ALMA) and Atacama Submillimeter Telescope Experiment. We find diffuse CO emission not only at the southern edge of the SNR as previously known, but also inside the X-ray shell. We spatially resolved nine molecular clouds using ALMA with an angular resolution of $5''$, corresponding to a spatial resolution of $\sim$1 pc at the distance of the LMC. Typical cloud sizes and masses are $\sim$2.0 pc and $\sim$100 $M_\odot$, respectively. High-intensity ratios of CO $J$ = 3-2 / 1-0 $> 1.5$ are seen toward the molecular clouds, indicating that shock-heating has occurred. Spatially resolved X-ray spectroscopy reveals that thermal X-rays in the center of N132D are produced not only behind a molecular cloud, but also in front of it. Considering the absence of a thermal component associated with the forward shock towards one molecular cloud located along the line of sight to the center of the remnant, this suggests that this particular cloud is engulfed by shock waves and is positioned on the near side of remnant. If the hadronic process is the dominant contributor to the gamma-ray emission, the shock-engulfed clouds play a role as targets for cosmic-rays. We estimate the total energy of cosmic-ray protons accelerated in N132D to be $\sim$0.5-$3.8 \times 10^{49}$ erg as a conservative lower limit, which is similar to that observed in Galactic gamma-ray SNRs.

中文翻译：

---

ALMA CO 对大麦哲伦星云中伽马射线超新星遗迹 N132D 的观测：宇宙射线质子照亮的冲击分子云的可能证据

N132D 是大麦哲伦星云 (LMC) 中最亮的伽马射线超新星遗迹 (SNR)。我们使用阿塔卡马大型毫米/亚毫米阵列 (ALMA) 和阿塔卡马亚毫米望远镜实验对 SNR 进行了 $^{12}$CO($J$ = 1-0, 3-2) 观测。我们不仅在 SNR 的南边缘发现了扩散的 CO 排放，而且在 X 射线壳内也有。我们使用 ALMA 空间解析了 9 个分子云，角分辨率为 $5''$，对应于 LMC 距离处的空间分辨率为 $\sim$1 pc。典型的云大小和质量分别为 $\sim$2.0 pc 和 $\sim$100 $M_\odot$。CO$J$ = 3-2 / 1-0 $> 1.5$ 的高强度比在分子云中可见，表明发生了激波加热。空间分辨 X 射线光谱表明，N132D 中心的热 X 射线不仅在分子云后面产生，也在分子云前面产生。考虑到不存在与沿视线位于残余物中心的分子云的前向冲击相关的热成分，这表明该特定云被冲击波吞没并位于残余物的近侧。如果强子过程是伽马射线发射的主要贡献者，那么被激波吞没的云就可以作为宇宙射线的目标。我们估计在 N132D 中加速的宇宙射线质子的总能量为 $\sim$0.5-$3.8\times 10^{49}$ erg 作为保守的下限，这与在银河伽马射线 SNR 中观察到的相似。