Measurement of Arcminute Scale Anisotropy with the BIMA Array

TL;DR

This study measures small-scale anisotropy in the CMB using the BIMA Array, detecting signals exceeding noise and analyzing power spectrum bins to understand cosmic fluctuations.

Contribution

It provides new measurements of arcminute scale CMB anisotropy and refines the power spectrum analysis with careful source removal and binning.

Findings

Detected CMB anisotropy at 68% confidence level

Measured flat band power of 14.2 μK at multipole 6864

Divided data into bins with significant anisotropy signals

Abstract

We report the results of our continued study of arcminute scale anisotropy in the Cosmic Microwave Background (CMB) with the Berkeley-Illinois-Maryland Array. The survey consists of ten independent fields selected for low infrared dust emission and lack of bright radio point sources. With observations from the Very Large Array (VLA) at 4.8 GHz, we have identified point sources which could act as contaminants in estimates of the CMB power spectrum and removed them in the analysis. Modeling the observed power spectrum with a single flat band power with average multipole of \ell_{eff}=6864, we find dT=14.2^{+4.8}_{-6.0} \mu K at 68% confidence. The signal in the visibility data exceeds the expected contribution from instrumental noise with 96.5% confidence. We have also divided the data into two bins corresponding to different spatial resolutions in the power spectrum. We find dT_1=16.6^{+5.3}_{-5.9} \mu K at 68% confidence for CMB flat band power described by an average multipole of \ell_{eff}=5237 and dT_2<26.5 \mu K at 95% confidence for \ell_{eff}=8748.