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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
The faint source population at 15.7 GHz - I. The radio properties
Monthly Notices of the Royal Astronomical Society, Volume 429, No. 3, Year 2013
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Description
We have studied a sample of 296 faint (>0.5 mJy) radio sources selected from an area of the Tenth Cambridge (10C) survey at 15.7 GHz in the Lockman Hole. By matching this catalogue to several lower frequency surveys (e.g. including a deep GMRT survey at 610 MHz, aWSRT survey at 1.4 GHz, NVSS, FIRST and WENSS) we have investigated the radio spectral properties of the sources in this sample; all but 30 of the 10C sources are matched to one or more of these surveys. We have found a significant increase in the proportion of flat-spectrum sources at flux densities below ≈1 mJy - the median spectral index between 15.7 GHz and 610 MHz changes from 0.75 for flux densities greater than 1.5 mJy to 0.08 for flux densities less than 0.8 mJy. This suggests that a population of faint, flat-spectrum sources are emerging at flux densities ≲ 1mJy. The spectral index distribution of this sample of sources selected at 15.7 GHz is compared to those of two samples selected at 1.4 GHz from FIRST and NVSS. We find that there is a significant flat-spectrum population present in the 10C sample which is missing from the samples selected at 1.4 GHz. The 10C sample is compared to a sample of sources selected from the SKADS Simulated Sky by Wilman et al. and we find that this simulation fails to reproduce the observed spectral index distribution and significantly underpredicts the number of sources in the faintest flux density bin. It is likely that the observed faint, flat-spectrum sources are a result of the cores of Fanaroff-Riley type I sources becoming dominant at high frequencies. These results highlight the importance of studying this faint, high-frequency population. © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.
Authors & Co-Authors
Whittam, Imogen H.
United Kingdom, Cambridge
Department of Physics
Riley, J. M.
United Kingdom, Cambridge
Department of Physics
David A. Green, David A.
United Kingdom, Cambridge
Department of Physics
Jarvis, Matthew J.
United Kingdom, Hatfield
University of Hertfordshire
South Africa, Bellville
University of the Western Cape
Prandoni, Isabella
Italy, Bologna
Inaf Istituto Di Astrofisica Spaziale e Fisica Cosmica, Bologna
Guglielmino, G.
Italy, Bologna
Inaf Istituto Di Astrofisica Spaziale e Fisica Cosmica, Bologna
Italy, Bologna
Alma Mater Studiorum Università Di Bologna
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Morganti, Raffaellla H.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Netherlands, Groningen
Kapteyn Instituut
R̈ottgering, Huub J.A.R.
Netherlands, Leiden
Sterrewacht Leiden
Garrett, Michael A.
Netherlands, Dwingeloo
Netherlands Foundation for Research in Astronomy
Netherlands, Leiden
Sterrewacht Leiden
Statistics
Citations: 29
Authors: 9
Affiliations: 8
Identifiers
Doi:
10.1093/mnras/sts478
ISSN:
00358711
e-ISSN:
13652966
Study Design
Cross Sectional Study
Case-Control Study
Study Approach
Quantitative