Follow-up observations at 16 and 33 GHz of extragalactic sources from WMAP 3-year data: II - Flux-density variability

Details Follow-up observations at 16 and 33 GHz of extragalactic sources from WMAP 3-year data: II - Flux-density variability Follow-up observations at 16 and 33 GHz of extragalactic sources from WMAP 3-year data: II - Flux-density variability

2009-07-22

arxiv.org/abs/0907.3843v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

12 pages and 10 figures

Scientific paper

Using the Arcminute Microkelvin Imager (AMI) at 16 GHz and the Very Small Array (VSA) at 33 GHz to make follow-up observations of sources in the New Extragalactic WMAP Point Source Catalogue, we have investigated the flux-density variability in a complete sample of 97 sources over timescales of a few months to approximately 1.5 years. We find that 53 per cent of the 93 sources, for which we have multiple observations, are variable, at the 99 per cent confidence level, above the flux density calibration uncertainties of approximately 4 per cent at 16 GHz; the fraction of sources having varied by more than 20 per cent is 15 per cent at 16 GHz and 20 per cent at 33 GHz. Not only is this common occurrence of variability at high frequency of interest for source physics, but strategies for coping with source contamination in CMB work must take this variability into account. There is no strong evidence of a correlation between variability and flux density for the sample as a whole. Using a maximum-likelihood method, we calculate the correlation in the variability at the two frequencies in a subset of sources classified as variable from both the AMI and VSA data and find the Pearson product-moment correlation coefficient to be very high (0.955 +/- 0.034). We also find the degree of variability at 16 GHz (0.202 +/- 0.028) to be very similar to that at 33 GHz (0.224 +/- 0.039). Finally, we have investigated the relationship between variability and spectral index, alpha_13.9^33.75 (where S proportional to nu^-alpha), and find a significant difference in the spectral indices of the variable sources (-0.06 +/- 0.05) and non-variable sources (0.13 +/- 0.04).

Affiliated with

Also associated with

No associations

Rating

Follow-up observations at 16 and 33 GHz of extragalactic sources from WMAP 3-year data: II - Flux-density variability does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Follow-up observations at 16 and 33 GHz of extragalactic sources from WMAP 3-year data: II - Flux-density variability, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Follow-up observations at 16 and 33 GHz of extragalactic sources from WMAP 3-year data: II - Flux-density variability will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-128311