Abstract
Using J and K_s band imaging obtained as part of the IMACS Cluster Building
Survey (ICBS) we measure Sérsic indices for 2160 field and cluster galaxies
at 0.31 < z < 0.54. We compare the distributions for spectroscopically
determined passive, continuously starforming, starburst, and poststarburst
systems and show that previously established spatial/statistical connections
between these types extend to their gross morphologies. Outside of cluster
cores, we find close structural ties between starburst and continuously
starforming, as well as poststarburst and passive types, but not between
starbursts and poststarbursts. These results independently support two
conclusions presented in a previous ICBS paper (Dressler et al.): 1) most
starbursts are the product of a non-disruptive triggering mechanism that is
insensitive to global environment, such as minor-mergers; 2) starbursts and
poststarbursts largely represent transient phases in the lives of "normal"
starforming and quiescent galaxies, respectively, originating from and
returning to these systems in closed "recycling" loops. In this picture,
spectroscopically identified poststarbursts constitute a minority of all
recently terminated starbursts and the starburst phenomenon is largely
decoupled from passive galaxy production in all but the densest environments.
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