Characterization of the Millimeter-Wave Polarization of Centaurus A with QUaD

TL;DR

This study measures the millimeter-wave polarization of Centaurus A using QUaD, providing precise polarization data that can serve as a calibration source for future cosmic microwave background experiments.

Contribution

The paper presents the first detailed polarization measurements of Centaurus A at millimeter wavelengths with quantified systematic errors, establishing it as a potential calibration source.

Findings

Measured polarization angles around -30 degrees at 100 and 150 GHz.

Quantified systematic and statistical errors in polarization measurements.

Demonstrated suitability of Cen A for calibration in CMB experiments.

Abstract

Centaurus (Cen) A represents one of the best candidates for an isolated, compact, highly polarized source that is bright at typical cosmic microwave background (CMB) experiment frequencies. We present measurements of the 4 degree by 2 degree region centered on Cen A with QUaD, a CMB polarimeter whose absolute polarization angle is known to 0.5 degrees. Simulations are performed to assess the effect of misestimation of the instrumental parameters on the final measurement and systematic errors due to the field's background structure and temporal variability from Cen A's nuclear region are determined. The total (Q, U) of the inner lobe region is (1.00 +/- 0.07 (stat.) +/- 0.04 (sys.), -1.72 +/- 0.06 +/- 0.05) Jy at 100 GHz and (0.80 +/- 0.06 +/- 0.06, -1.40 +/- 0.07 +/- 0.08) Jy at 150 GHz, leading to polarization angles and total errors of -30.0 +/- 1.1 degrees and -29.1 +/- 1.7 degrees. These measurements will allow the use of Cen A as a polarized calibration source for future millimeter experiments.