Properties of the KISS Green Pea Galaxies
Samantha W. Brunker, John J. Salzer, Steven Janowiecki, Rose A. Finn, George Helou
Abstract
Abstract Green peas (GPs) are a class of extreme star-forming galaxies (SFGs) at intermediate redshifts, originally discovered via color selection using multifilter, wide-field survey imaging data. They are commonly thought of as being analogs of high-redshift Ly α -emitting galaxies. The defining characteristic of GP galaxies is a high-excitation nebular spectrum with very large equivalent width lines, leading to the recognition that GP-like galaxies can also be identified in samples of emission-line galaxies. Here we compare the properties a sample of [O iii ]-selected SFGs ( z = 0.29–0.41) from the KPNO International Spectroscopic Survey (KISS) with the color-selected GPs. We find that the KISS [O iii ]-selected galaxies overlap with the parameter space defined by the color-selected GPs; the two samples appear to be drawn from the same population of objects. We compare the KISS GPs with the full H α -selected KISS SFG sample ( z < 0.1) and find that they are extreme systems. Many appear to be young systems at their observed look-back times (3–4 Gyr), with more than 90% of their rest-frame B -band luminosity coming from the starburst population. We compute the volume density of the KISS red (KISSR) GPs at z = 0.29–0.41 and find that they are extremely rare objects. We do not see galaxies as extreme as the KISSR GPs in the local universe, although we recognize several lower-luminosity systems at z < 0.1.