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First results from the Very Small Array -- III. The CMB power spectrum

Paul F. Scott, Pedro Carreira, Kieran Cleary, Rod D. Davies, Richard Davis, Clive Dickinson, Keith Grainge, Carlos Gutierrez, Michael P. Hobson, Michael E. Jones, Ruediger Kneissl, Anthony Lasenby, Klaus Maisinger, Guy Pooley, Rafael Rebolo, Jose Alberto Rubino Martin, Pedro Sosa Molina, Ben Rusholme, Richard Saunders, Richard Savage, Anze Slosar, Angela C. Taylor, David Titterington, Elizabeth Waldram, Robert A. Watson, Althea Wilkinson

Abstract

We present the power spectrum of the fluctuations in the cosmic microwave background detected by the Very Small Array (VSA) in its first season of observations in its compact configuration. We find clear detections of first and second acoustic peaks at l~200 and l~550, plus detection of power on scales up to l=800. The VSA power spectrum is in very good agreement with the results of the Boomerang, Dasi and Maxima telescopes despite the differing potential systematic errors.

First results from the Very Small Array -- III. The CMB power spectrum

Abstract

We present the power spectrum of the fluctuations in the cosmic microwave background detected by the Very Small Array (VSA) in its first season of observations in its compact configuration. We find clear detections of first and second acoustic peaks at l~200 and l~550, plus detection of power on scales up to l=800. The VSA power spectrum is in very good agreement with the results of the Boomerang, Dasi and Maxima telescopes despite the differing potential systematic errors.

Paper Structure

This paper contains 18 sections, 8 equations, 6 figures, 3 tables.

Table of Contents

  1. Introduction
  2. Observations and Initial Data Processing
  3. The observations
  4. Initial Data Processing
  5. Derivation of the Power Spectrum
  6. Window functions
  7. Data Checks
  8. Test of data reduction procedure
  9. The Local Spurious Signal
  10. Foreground Source Subtraction
  11. Galactic Foregrounds
  12. Noise Estimation
  13. $\chi^{2}$ Tests
  14. The Power Spectrum
  15. Discussion
  16. ...and 3 more sections

Figures (6)

  • Figure 1: Window functions for the combined data set. The functions are normalised to unit area, and different bins are plotted with different linestyles to allow easier visual differentiation.
  • Figure 2: Power spectra of the recovered common signal from the two VSA2 fields (squares) and from a pair of simulated datasets with no common signal (i.e. independent noise only) (crosses). The pairs of points have been separated laterally for clarity. Coverage of the $uv$-plane and the thermal noise level are identical for both the real data and the simulation.
  • Figure 3: Two examples of recovered power spectra from simulated CMB observations with (filled circles, solid lines) and without (open circles, dotted lines) the known sources in the VSA1 field added. The differences arise from chance interactions between the sources and individual CMB features.
  • Figure 4: Simulated power spectra for known sources plus a statistical distribution of weaker sources (upper plot) and for the distribution of weaker sources alone (lower plot). For comparison the dashed curve shows the predicted power spectrum for a CDM model.
  • Figure 5: Combined CMB power spectrum from the three mosaiced VSA fields. The error-bars represent $1\sigma$ limits; the two sets of data points correspond to alternative interleaved binnings of the data.
  • ...and 1 more figures