Our sensitive (sigma(n) approximate to 572 nJy beam(-1)), high-resolution (FWHM theta(1/2) = 0"22 approximate to 2 kpc at z greater than or similar to 1), 10 GHz image covering a single Karl G.. Jansky Very Large Array (VLA) primary beam (FWHM circle minus(1/2) approximate to 4.'25) in the GOODS-N field contains 32 sources with S-p greater than or similar to 2 mu Jy beam(-1) and optical and/or near-infrared (OIR) counterparts. Most are about as large as the star-forming regions that power them. Their median FWHM major axis is <theta(M)>= 167 +/- 32 mas approximate to 1.2 +/- 0.28 kpc, with rms scatter approximate to 91 mas approximate to 0.79 kpc. In units of the effective radius re that encloses half their flux, these radio sizes are re approximate to 69 +/- 13 mas approximate to 509 +/- 114 pc, with rms scatter approximate to 38 mas approximate to 324 pc. These sizes are smaller than those measured at lower radio frequencies, but agree with dust emission sizes measured at mm/sub-mm wavelengths and extinction-corrected H alpha sizes. We made a lowresolution (theta(1/2) = 1."0) image with approximate to 10x better brightness sensitivity, in order to detect extended sources and measure matched-resolution spectral indices alpha(10 GHz)(1.4 GHz) 10 GHz. It contains six new sources with Sp. 3.9 mJy beam-1 and OIR counterparts. The median redshift of all 38 sources is similar to z similar to = 1.24 +/- 0.15. The 19 sources with 1.4 GHz counterparts have a median spectral index of <alpha(1.4 GHz) (10 GHz)> = -0.74 +/- 0.10 10 GHz, with rms scatter approximate to 0.35. Including upper limits on a for sources not detected at 1.4 GHz flattens the median to <alpha(1.4 GHz) (10 GHz)> greater than or similar to -0.61 10 GHz, suggesting that the mu Jy radio sources at higher redshifts-and hence those selected at higher rest-frame frequencies-may have flatter spectra. If the non-thermal spectral index is alpha(NT) approximate to -0.85, the median thermal fraction of sources selected at median rest-frame frequency approximate to 20 GHz is greater than or similar to 48%.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/624727 |
| Date | 11 April 2017 |
| Creators | Murphy, Eric J., Momjian, Emmanuel, Condon, James J., Chary, Ranga-Ram, Dickinson, Mark, Inami, Hanae, Taylor, Andrew R., Weiner, Benjamin J. |
| Contributors | Univ Arizona, Dept Astron, Steward Observ |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2017. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/0004-637X/839/i=1/a=35?key=crossref.8e7697d73d17266acef92b88ab47f40f |
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