The Origin and Optical Depth of Ionizing Radiation in the "Green Pea" Galaxies

摘要: Although Lyman continuum (LyC) radiation from star-forming galaxies likely drove the reionization of Universe, observations at low redshift generally indicate LyC escape fractions. However, extreme [O III]/[O II] ratios z=0.1-0.3 Green Pea may be due to high fractions ionizing radiation. To analyze optical depths and sources these rare, compact starbursts, we compare nebular photoionization stellar population models with observed emission lines in Peas' SDSS spectra. We focus on six most Peas, highest best candidates for escaping The Balmer line equivalent widths He I {\lambda}3819 Peas support young ages 3-5 Myr, II {\lambda}4686 five signals presence hard sources. Ionization by active galactic nuclei or high-mass X-ray binaries is inconsistent ages. stacked spectra reveal no Wolf-Rayet (WR) features, tentatively detect WR features three Peas. Based ratios, find that stars, chemically homogeneous O shocks could produce emission. If hot stars are responsible, ambiguous. accounting lowers inferred depth suggests optically thin. optimize Lyman-continuum radiation; they old enough supernovae winds reshape interstellar medium, but possess large numbers UV-luminous stars.