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2mm Observations and the Search for High-Redshift Dusty Star-forming Galaxies

Author:
L. L. Cowie, A. J. Barger, F. E. Bauer
Keyword:
Astrophysics, Astrophysics of Galaxies, Astrophysics of Galaxies (astro-ph.GA)
journal:
--
date:
2023-05-25 16:00:00
Abstract
Finding high-redshift (z>>4) dusty star-forming galaxies is extremely challenging. It has recently been suggested that millimeter selections may be the best approach, since the negative K-correction makes galaxies at a given far-infrared (FIR) luminosity brighter at z>4 than those at z=2-3. Here we analyze this issue using a deep ALMA 2mm sample obtained by targeting ALMA 870um priors (these priors were the result of targeting SCUBA-2 850um sources) in the GOODS-S. We construct the prior-based 2mm galaxy number counts and compare them with published blank field-based 2mm counts, finding good agreement down to 0.2mJy. Only a fraction of the current 2mm extragalactic background light is resolved, and we estimate what observational depths may be needed to resolve it fully. By complementing the 2mm ALMA data with a deep SCUBA-2 450um sample in the GOODS-S, we exploit the steep gradient with redshift of the 2mm to 450um flux density ratio to estimate redshifts for these galaxies without spectroscopic or robust optical/near-infrared photometric redshifts. Our observations measure galaxies with star formation rates in excess of 250 solar masses per year. For these galaxies, the star formation rate densities fall by a factor of 9 from z=2-3 to z=5-6.
PDF: 2mm Observations and the Search for High-Redshift Dusty Star-forming Galaxies.pdf
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