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The Properties of Microjansky Radio Sources in the HDF-N, SSA13, and SSA22 Fields

S. C. Chapman·A. J. Barger·L. L. Cowie·D. Scott·C. Borys·P. Capak·E. B. Fomalont·G. F. Lewis·E. A. Richards·A. T. Steffen·G. Wilson·M. Yun
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Abstract

(abridged) We present multiwavelength observations for a large sample of microjansky radio sources detected in ultradeep 1.4GHz maps centered on the Hubble Deep Field-North (HDF-N) and the Hawaii Survey Fields SSA13 and SSA22. Our spectroscopic redshifts for 169 radio sources reveal a flat median redshift distribution, and these sources are hosted by similarly luminous optical L* galaxies, regardless of redshift. This is a serious concern for radio estimates of the local star formation rate density, as a substantial fraction of the ultraviolet luminosity density is generated by sub-L* galaxies at low redshifts. From our submillimeter measurements for 278 radio sources, we find error-weighted mean 850micron fluxes of 1.72$\pm$0.09 mJy for the total sample, 2.37$\pm$0.13 mJy for the optically-faint (I>23.5) subsample, and 1.04$\pm$0.13 mJy for the optically-bright (I<23.5) subsample. We significantly (>3σ) detect in the submillimeter 50 of the radio sources, 38 with I>23.5. Spectroscopic redshifts for three of the I<23.5 submillimeter-detected radio sources are in the range z=1.0-3.4, and all show AGN signatures. Using only the submillimeter mapped regions we find that 69\pm9% of the submillimeter-detected radio population are at I>23.5. We also find that 66\pm7% of the S850>5 mJy (>4σ) sources are radio-identified. We find that millimetric redshift estimates at low redshifts are best made with a FIR template intermediate between a Milky Way type galaxy and a starburst galaxy, and at high redshifts with an Arp220 template.

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S. C. Chapman, A. J. Barger, L. L. Cowie, D. Scott, C. Borys, P. Capak, E. B. Fomalont, G. F. Lewis, E. A. Richards, A. T. Steffen, G. Wilson, M. Yun. 2002-11-05. The Properties of Microjansky Radio Sources in the HDF-N, SSA13, and SSA22 Fields. https://doi.org/10.1086/345980

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