Detection of CO Hot Spots Associated with Young Clusters in the Southern Starburst Galaxy NGC 1365

Abstract

We have used the Submillimeter Array for the first interferometric CO imaging toward the starburst-Seyfert nucleus of the southern barred spiral galaxy NGC 1365, which is one of the four galaxies within 30 Mpc that have L 8-1000 μm ≥ 10 11 L ☉ . Our mosaic maps of 12 CO, 13 CO, and C 18 O ( J = 2-1) emission at up to 2'' (200 pc) resolutions have revealed a circumnuclear gas ring and several CO clumps in the central 3 kpc. The molecular ring shows morphological and kinematical signs of bar-driven gas dynamics, and the region as a whole is found to follow the star formation laws of Kennicutt. We have found that some of the gas clumps and peaks in CO brightness temperature, which we collectively call CO hot spots, coincide with the radio and mid-infrared sources previously identified as dust-enshrouded super star clusters. This hot spot-cluster association suggests that either the formation of the most massive clusters took place in large molecular gas concentrations (of Σ mol ~ 10 3 M ☉ pc -2 in 200 pc scales) or the clusters have heated their ambient gas to cause or enhance the CO hot spots. The active nucleus is in the region of weak CO emission and is not associated with distinctive molecular gas properties.