E plus A galaxies in the near-infrared: Broadband photometry

This paper presents near-IR photometry of a selected sample of southern hem isphere E + A galaxies. The sample includes 50 galaxies from nearby (z simi lar to 0.05) and distant (z similar to 0.3) clusters, as well as E + A gala xies from the field (z similar to 0.1). Observations include 13 normal earl y-type galaxies from the held and from clusters to be compared with the E A sample. The photometry includes J, H, and K, apparent magnitudes and col ors. Observed colors are obtained from the apparent total magnitudes and co mpared with those of the GISSEL96 spectrophotometric models of galaxy evolu tion. There is an overall agreement between integrated colors of models and observed ones, for both the E + A galaxies located in clusters and those i n the held, at z less than or similar to 0.1. However, large differences be tween colors predicted from models and those observed in E + A galaxies loc ated in clusters at z similar to 0.3 are found. We also compute rest-frame colors for all the galaxies using two different sets of K-corrections and o btain average colors for all the samples. This work investigates systematic properties of the E + A sample as a function of its environment, Results s eem to indicate that cluster E + A galaxies (at low redshift) are bluer tha n field E + A galaxies at z similar to 0.1. Even this conclusion does not d epend on whether we use comoving or rest-frame colors or on the models used to obtain rest-frame colors; the difference is not significant enough, con sidering color dispersions between the samples. If the differences are real , they could imply a different stellar content for the E + A galaxies locat ed in the held compared with those located in the cluster E + A galaxies.