Small angular scale CMB anisotropies from CBI and BIMA experiments: 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 a few arcminutes and below. Though the reported excess power at l∼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 redshift contribution, another strong possibility for anisotropies at very small scales involves nonstandard 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 redshifts contribute to small-scale temperature anisotropies, it may be 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, multifrequency observations may be a necessary aspect to allow an additional possibility to distinguish between these different scenarios.

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