Small Angular Scale CMB Anisotropies from CBI and BIMA: Early Universe or Local structures ?

Abstract

The advent of high resolution cosmic microwave background (CMB) experiments now allows studies on the temperature fluctuations at scales corresponding to few arcminutes and below. Though the reported excess power at $\ell \sim 2000 - 6000$ by CBI and BIMA is roughly consistent with a secondary contribution resulting from the Sunyaev-Zeldovich effect, this requires a higher normalization for the matter power spectrum than measured by other means. In addition to a local red-shift contribution, another strong possibility for anisotropies at very small scales involve non-standard aspects of inflationary models. To distinguish between contributions from early universe and local structures, including a potential point source contribution, and to understand the extent to which structures at low red-shifts contribute to small scale temperature anisotropies, it maybe necessary to perform a combined study involving CMB and the large scale structure. We suggest a cross-correlation of the temperature data with a map of the large scale structure, such as the galaxy distribution. For next generation small angular scale CMB experiments, multi-frequency observations may be a necessary aspect to allow an additional possibility to distinguish between these different scenarios.