RESOLVING THE RADIO SOURCE BACKGROUND: DEEPER UNDERSTANDING THROUGH CONFUSION

Journal Article · Wed Oct 10 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/758/1/23· OSTI ID:22092104

Condon, J. J.; Cotton, W. D.; Fomalont, E. B.; Kellermann, K. I. ^[1]; Miller, N. ^[2]; Perley, R. A. ^[3]; Scott, D.; Vernstrom, T.; Wall, J. V. ^[4]

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1. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
2. Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States)
3. National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 (United States)
4. Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1C1 (Canada)

We used the Karl G. Jansky Very Large Array to image one primary beam area at 3 GHz with 8'' FWHM resolution and 1.0 {mu}Jy beam{sup -1} rms noise near the pointing center. The P(D) distribution from the central 10 arcmin of this confusion-limited image constrains the count of discrete sources in the 1 < S({mu}Jy) < 10 range. At this level, the brightness-weighted differential count S {sup 2} n(S) is converging rapidly, as predicted by evolutionary models in which the faintest radio sources are star-forming galaxies; and Almost-Equal-To 96% of the background originating in galaxies has been resolved into discrete sources. About 63% of the radio background is produced by active galactic nuclei (AGNs), and the remaining 37% comes from star-forming galaxies that obey the far-infrared (FIR)/radio correlation and account for most of the FIR background at {lambda} Almost-Equal-To 160 {mu}m. Our new data confirm that radio sources powered by AGNs and star formation evolve at about the same rate, a result consistent with AGN feedback and the rough correlation of black hole and stellar masses. The confusion at centimeter wavelengths is low enough that neither the planned Square Kilometre Array nor its pathfinder ASKAP EMU survey should be confusion limited, and the ultimate source detection limit imposed by 'natural' confusion is {<=}0.01 {mu}Jy at {nu} = 1.4 GHz. If discrete sources dominate the bright extragalactic background reported by ARCADE 2 at 3.3 GHz, they cannot be located in or near galaxies and most are {<=}0.03 {mu}Jy at 1.4 GHz.

• OSTI ID: 22092104
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 758; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ASTRONOMY
ASTROPHYSICS
BLACK HOLES
BRIGHTNESS
CORRELATIONS
COSMIC RADIO SOURCES
COSMOLOGY
GALAXIES
GALAXY NUCLEI
GHZ RANGE
IMAGES
RESOLUTION
SENSITIVITY
STARS
WAVELENGTHS