Extragalactic Radio Sources and the WMAP Cold Spot
Abstract
We detect a dip of 20-45% in the surface brightness and number counts of NVSS sources smoothed to a few degrees at the location of the WMAP cold spot. The dip has structure on scales of approximately 1-10 degrees. Together with independent all-sky wavelet analyses, our results suggest that the dip in extragalactic brightness and number counts and the WMAP cold spot are physically related, i.e., that the coincidence is neither a statistical anomaly nor a WMAP foreground correction problem. If the cold spot does originate from structures at modest redshifts, as we suggest, then there is no remaining need for non-Gaussian processes at the last scattering surface of the CMB to explain the cold spot. The late integrated Sachs-Wolfe effect, already seen statistically for NVSS source counts, can now be seen to operate on a single region. To create the magnitude and angular size of the WMAP cold spot requires a ~140 Mpc radius completely empty void at z<=1 along this line of sight. This is far outside the current expectations of the concordance cosmology, and adds to the anomalies seen in the CMB.
Keywords
Cite
@article{arxiv.0704.0908,
title = {Extragalactic Radio Sources and the WMAP Cold Spot},
author = {Lawrence Rudnick and Shea Brown and Liliya R. Williams},
journal= {arXiv preprint arXiv:0704.0908},
year = {2009}
}
Comments
revised version, ApJ, in press