We present the results of CO ( 1–0 ) observations of the host galaxy of a Type I superluminous supernova ( SLSN-I ) , SN 2017egm , one of the closest SLSNe-I at z = 0.03063 , by using the Atacama Large Millimeter/submillimeter Array .
The molecular gas mass of the host galaxy is M _ { gas } = ( 4.8 \pm 0.3 ) \times 10 ^ { 9 } M _ { \odot } , placing it on the sequence of normal star-forming galaxies in an M _ { gas } –star-formation rate ( SFR ) plane .
The molecular hydrogen column density at the location of SN 2017egm is higher than that of the Type II SN PTF10bgl , which is also located in the same host galaxy , and those of other Type II and Ia SNe located in different galaxies , suggesting that SLSNe-I have a preference for a dense molecular gas environment .
On the other hand , the column density at the location of SN 2017egm is comparable to those of Type Ibc SNe .
The surface densities of molecular gas and the SFR at the location of SN 2017egm are consistent with those of spatially resolved local star-forming galaxies and follow the Schmidt–Kennicutt relation .
These facts suggest that SLSNe-I can occur in environments with the same star-formation mechanism as in normal star-forming galaxies .