RX J0046.5 - 7308 is a shell-type supernova remnant ( SNR ) in the Small Magellanic Cloud ( SMC ) .
We carried out new ^ { 12 } CO ( J = 1–0 , 3–2 ) observations toward the SNR using Mopra and the Atacama Submillimeter Telescope Experiment .
We found eight molecular clouds ( A–H ) along the X-ray shell of the SNR .
The typical cloud size and mass are \sim 10–15 pc and \sim 1000–3000 M _ { \sun } , respectively .
The X-ray shell is slightly deformed and has the brightest peak in the southwestern shell where two molecular clouds A and B are located .
The four molecular clouds A , B , F , and G have high intensity ratios of ^ { 12 } CO ( J = 3–2 ) / ^ { 12 } CO ( J = 1–0 ) > 1.2 , which are not attributable to any identified internal infrared sources or high-mass stars .
The H i cavity and its expanding motion are found toward the SNR , which are likely created by strong stellar winds from a massive progenitor .
We suggest that the molecular clouds A–D , F , and G , and H i clouds within the wind-blown cavity at V _ { \mathrm { LSR } } = 117.1 –122.5 km s ^ { -1 } are associated with the SNR .
The X-ray spectroscopy reveals the dynamical age of 26000 ^ { +1000 } _ { -2000 } yr and the progenitor mass of \gtrsim 30 ~ { } M _ { \sun } , which is also consistent with the proposed scenario .
We determine physical conditions of the giant molecular cloud LIRS 36A using the large velocity gradient analysis with archival datasets of the Atacama Large Millimeter/submillimeter Array ; the kinematic temperature is 72 ^ { +50 } _ { -37 } K and the number density of molecular hydrogen is 1500 ^ { +600 } _ { -300 } cm ^ { -3 } .
The next generation of \gamma -ray observations will allow us to study the pion-decay \gamma -rays from the molecular clouds in the SMC SNR .