Cosmology

Abstract:

Co-addition of blank-field FIRST data at the location of over 8000 QSOs in the 2QZ survey has yielded statistical detections of radio quiet QSOs with median flux levels of 20-40microJy. We show that the total radio flux of radio-quiet QSOs in the 2QZ is consistent with a smooth extrapolation of the 2QZ radio-loud QSO number-flux distribution based on the slope of the relation flattening near the FIRST flux limit. However, we are unable to distinguish a smooth extrapolation of the luminosity function to faint levels from a bimodal luminosity function with a break close to or below the FIRST radio detection limit. We also demonstrate that the redshift dependence of the median radio-to-optical spectral index for these radio quiet QSOs is consistent with that obtained for individual radio-loud 2QZ QSOs detected by FIRST.

Abstract:

We present coincident observations of the Cosmic Microwave Background (CMB) from the Very Small Array (VSA) and Cosmic Background Imager (CBI) telescopes. The consistency of the full datasets is tested in the map plane and the Fourier plane, prior to the usual compression of CMB data into flat bandpowers. Of the three mosaics observed by each group, two are found to be in excellent agreement. In the third mosaic, there is a 2 sigma discrepancy between the correlation of the data and the level expected from Monte Carlo simulations. This is shown to be consistent with increased phase calibration errors on VSA data during summer observations. We also consider the parameter estimation method of each group. The key difference is the use of the variance window function in place of the bandpower window function, an approximation used by the VSA group. A re-evaluation of the VSA parameter estimates, using bandpower windows, shows that the two methods yield consistent results.