Galaxy formation and evolution

Abstract:

integral field spectroscopy in the K-band (1.9-2.4 mu m) was performed on four IR-bright star clusters in NGC4038/39 ("The Antennae"). Two of them (hereafter F1 and F2) are located in the overlap region of the two galaxies, and together comprise approximate to 25% of the total 15 mu m and approximate to 10% of the total non-thermal 4.8 GHz emission from this pair of merging galaxies. The other two clusters, each of them spatially resolved into two components, are located in the northern galaxy, one on the eastern (F3) and one on the western (F4) "loop" of blue clusters. Comparing our analysis of Br gamma, CO-bandheads, H alpha (from archival HST data), and V-K colours with stellar population synthesis models indicates that the clusters are extincted (A(v) approximate to 0.7 - 4.3 mags) and young, displaying a significant age spread (4 - 10x10(6) yrs). Using our derived age estimates and assuming the parameters of the IMF, we find that these clusters have masses that range from a few x10(5) to a few x10(6) M-circle dot.