Radio and Submillimeter Continuum Observations of High-Redshift Galaxies

Abstract

AbstractObserving galaxies in the radio and submillimeter continuum has the advantage of being unaffected by dust extinction, which is a major drawback of studying galaxy evolution using optical data. Submillimeter single-dish surveys have made tremendous progress in understanding the high-redshift dusty population, but the low angular resolution of single-dish telescopes has also hampered these studies. Our recent JCMT and SMA imaging of high-redshift submillimeter sources revealed z > 4 objects that are radio and optically faint. Such objects cannot be easily identified with the combination of submillimeter single-dish and radio imaging. We also found a large fraction of multiple objects that are blended in single-dish images. Such objects may be early-stage mergers, or dusty starbursts in group environments. Since our work, larger surveys with PdBI and ALMA have been carried out to further address these issues. Additional to submillimeter imaging, future ultradeep EVLA imaging at 20 cm can also detect large samples of ultraluminous star forming galaxies at z ≳ 2. Sensitivities in radio and submillimeter observations have different redshift and dust temperature dependencies. Radio observations are also less affected by confusion. It will be necessary to combine deep surveys in both wavebands in order to achieve a more complete picture of the evolution of high-redshift star forming galaxies.