The Atacama Cosmology Telescope: Calibration with WMAP Using Cross-Correlations

TL;DR

This paper introduces a new calibration method for the Atacama Cosmology Telescope using cross-correlations with WMAP, achieving 2% calibration accuracy and producing a combined high signal-to-noise map.

Contribution

The paper presents a novel calibration technique leveraging WMAP cross-correlations to improve ACT map accuracy and combines data for enhanced analysis.

Findings

Achieved 2% calibration uncertainty in temperature.

Produced a combined ACT-WMAP map with high signal-to-noise.

Enhanced the precision of cosmological parameter estimation.

Abstract

We present a new calibration method based on cross-correlations with WMAP and apply it to data from the Atacama Cosmology Telescope (ACT). ACT's observing strategy and map making procedure allows an unbiased reconstruction of the modes in the maps over a wide range of multipoles. By directly matching the ACT maps to WMAP observations in the multipole range of 400 < ell < 1000, we determine the absolute calibration with an uncertainty of 2% in temperature. The precise measurement of the calibration error directly impacts the uncertainties in the cosmological parameters estimated from the ACT power spectra. We also present a combined map based on ACT and WMAP data that has high signal-to-noise over a wide range of multipoles.