We present the results of an eight-year long monitoring of the radio emission from the Luminous Infrared Galaxy ( LIRG ) NGC 7469 , using 8.4 GHz Very Large Array ( VLA ) observations at 0.3 ” resolution .
Our monitoring shows that the late time evolution of the radio supernova SN 2000ft follows a decline very similar to that displayed at earlier times of its optically thin phase .
The late time radio emission of SN 2000ft is therefore still being powered by its interaction with the presupernova stellar wind , and not with the interstellar medium ( ISM ) .
Indeed , the ram pressure of the presupernova wind is \rho _ { w } v _ { w } ^ { 2 } \approx 7.6 \times 10 ^ { -9 } { dyn } { cm } ^ { -2 } , at a supernova age of t \approx 2127 days , which is significantly larger than the expected pressure of the ISM around SN 2000ft .
At this age , the SN shock has reached a distance r _ { sh } \approx 0.06 pc , and our observations are probing the interaction of the SN with dense material that was ejected by the presupernova star about 5820 years prior to its explosion .
From our VLA monitoring , we estimate that the swept-up mass by the supernova shock after about six years of expansion is M _ { sw } \approx 0.29 { M } _ { \odot } , assuming an average expansion speed of the supernova of 10 ^ { 4 } km s ^ { -1 } .

We also searched for recently exploded core-collapse supernovae in our VLA images .
Apart from SN 2000ft ( S _ { \nu } \approx 1760 \mu Jy at its peak , corresponding to 1.1 \times 10 ^ { 28 } erg s ^ { -1 } Hz ^ { -1 } ) , we found no evidence for any other radio supernova ( RSN ) more luminous than \approx 6.0 \times 10 ^ { 26 } erg s ^ { -1 } Hz ^ { -1 } , which suggests that no other Type IIn SN has exploded since 2000 in the circumnuclear starburst of NGC 7469 .