The nature of near-ultraviolet-selected objects in the Chandra Deep Field-South

摘要

We present the first results of the pure parallel near-UV observations with the Wide Field Planetary Camera 2 (WFPC2) in the Chandra Deep Field-South. The main goal is to search for the population of objects that contributes to the rise in the volume-averaged star formation rate at intermediate redshifts (z<1). A total of 34 objects were identified in the WFPC2 images and their counterparts found in images from the Advanced Camera for Surveys. We use template fitting of the spectral energy distributions to classify the objects and found that 17 are starbursts, nine are late-type galaxies, two are early-type galaxies, and six are stars; two of the late types and one of the starbursts are X-ray sources. The colors of the starbursts were reproduced by the stellar evolutionary synthesis code Starburst99, which shows a mixed population of bursts with ages less than 1 Gyr. Analysis of the light concentration, asymmetry, and clumpiness shows that this sample is a mixed bag, containing dwarf ellipticals, early and late spirals, and peculiar objects that resemble mergers in progress. [References: 25]