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SUMMARY:The Faint Source Population at 15.7 GHz - Imogen Whittam (Cavendis
 h Astrophysics)
DTSTART:20130219T163000Z
DTEND:20130219T170000Z
UID:TALK42605@talks.cam.ac.uk
CONTACT:David Titterington
DESCRIPTION: I have studied a sample of 296 faint (> 0.5 mJy) radio source
 s 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 s
 urveys (e.g. including a deep GMRT survey at 610 MHz\, a WSRT survey at 1.
 4 GHz\, NVSS\, FIRST and WENSS) we have investigated the radio spectral pr
 operties 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 incr
 ease 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 le
 ss than 0.8 mJy. This suggests that a population of faint\, flat spectrum 
 sources is emerging at flux densities less than 1 mJy.\n     The spectral 
 index distribution of this sample of sources selected at 15.7 GHz is compa
 red to those of two samples selected at 1.4 GHz from FIRST and NVSS. We fi
 nd 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 sam
 ple is compared to a sample of sources selected from the SKADS Simulated S
 ky by Wilman et al. and we find that this simulation fails to reproduce th
 e 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 FRI s
 ources becoming dominant at high frequencies. These results highlight the 
 importance of studying this faint\, high frequency population.\n
LOCATION:Ryle Seminar Room\, Cavendish Laboratory
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