engleski

Quest for COSMOS Submillimeter Galaxy Counterparts using CARMA and VLA : Identifying Three High-redshift Starburst Galaxies

We report on interferometric observations at 1.3 mm at 2''-3'' resolution using the Combined Array for Research in Millimeter- wave Astronomy. We identify multi-wavelength counterparts of three submillimeter galaxies (SMGs ; F 1 mm > 5.5 mJy) in the COSMOS field, initially detected with MAMBO and AzTEC bolometers at low, ~10''-30'', resolution. All three sources— AzTEC/C1, Cosbo-3, and Cosbo-8—are identified to coincide with positions of 20 cm radio sources. Cosbo-3, however, is not associated with the most likely radio counterpart, closest to the MAMBO source position, but with that farther away from it. This illustrates the need for intermediate-resolution (~2'') mm- observations to identify the correct counterparts of single-dish- detected SMGs. All of our three sources become prominent only at NIR wavelengths, and their mm-to-radio flux based redshifts suggest that they lie at redshifts z >~ 2. As a proof of concept, we show that photometric redshifts can be well determined for SMGs, and we find photometric redshifts of 5.6 ± 1.2, 1.9+0.9 - 0.5, and ~4 for AzTEC/C1, Cosbo-3, and Cosbo-8, respectively. Using these we infer that these galaxies have radio-based star formation rates of >~ 1000 M sun yr-1and IR luminosities of ~1013 L sun consistent with properties of high-redshift SMGs. In summary, our sources reflect a variety of SMG properties in terms of redshift and clustering, consistent with the framework that SMGs are progenitors of z ~ 2 and today's passive galaxies.

galaxies: active; galaxies: distances and redshifts; galaxies: high-redshift; galaxies: starburst; submillimeter: galaxies

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