Observing with NIKA2Pol from the IRAM 30m telescope. Early results on the commissioning phase

TL;DR

This paper presents early polarization observations of extended sources like the Crab nebula using NIKA2 on the IRAM 30m telescope, highlighting initial results and systematic uncertainties during commissioning.

Contribution

It introduces the NIKA2 polarimeter's capabilities and reports preliminary polarization maps and flux measurements from the commissioning phase.

Findings

Polarization flux of Crab nebula consistent with expectations

Initial polarization maps obtained during commissioning

Systematic uncertainties in polarization angle measurements identified

Abstract

The NIKA2 polarization channel at 260 GHz (1.15 mm) has been proposed primarily to observe galactic star-forming regions and probe the critical scales between 0.01-0.05 pc at which magnetic field lines may channel the matter of interstellar filaments into growing dense cores. The NIKA2 polarimeter consists of a room temperature continuously rotating multi-mesh HWP and a cold polarizer that separates the two orthogonal polarizations onto two 260 GHz KIDs arrays. We describe in this paper the preliminary results obtained during the most recent commissioning campaign performed in December 2018. We concentrate here on the analysis of the extended sources, while the observation of compact sources is presented in a companion paper [12]. We present preliminary NIKA2 polarization maps of the Crab nebula. We find that the integrated polarization intensity flux measured by NIKA2 is consistent with expectations.In terms of polarization angle, we are still limited by systematic uncertainties that will be further investigated in the forthcoming commissioning campaigns.