Unveiling the ongoing star formation in the starburst Galaxy NGC 253

The H2S 2(2), (0)-2(1, 1) and SO 5(5)-4(4) transitions were observed simultaneously toward the starburst galaxy NGC 253 using the Submillimeter Array. Two H2S emission peaks are found at positions similar to 2 '' northeast (30 pc) and similar to 5 '' southwest (80 pc) from the galactic center, associated with the circumnuclear disk and coinciding with the inner ring structure seen on the SiO map by Garcia-Burillo and coworkers. SO emission is detected, weakly, only toward the northeast. By combining data in the literature, we estimate H2S rotational temperatures of 130 K toward the northeast H2S peak and 46 K toward the southwest peak and derive H2S column densities of similar to 3 and similar to 1 x 10(15) cm(-2) and SO column densities of similar to 4 and <= 3 x 10(14) cm(-2) toward the northeast and southwest peaks, respectively. The fractional abundances, relative to molecular hydrogen, are and for H2S and SO, comparable with the values observed in Galactic massive star forming cores. The H2S emission is supposed to trace the ongoing star formation through hot core activity, and a rough comparison with the massive star forming region Orion KL indicates that several thousands of Orion KL-like cores may exist toward each of the H2S peaks.