Absolute calibration of the polarisation angle for future CMB B-mode experiments from current and future measurements of the Crab nebula

Abstract

A tremendous international effort is currently dedicated to observing the so-called primordial B modes of the Cosmic Microwave Background (CMB) polarisation. If measured, this faint signal imprinted by the primordial gravitational wave background, would be an evidence of the inflation epoch and quantify its energy scale, providing a rigorous test of fundamental physics far beyond the reach of accelerators. At the unprecedented sensitivity level that the new generation of CMB experiments aims to reach, every uncontrolled instrumental systematic effect will potentially result in an analysis bias that is larger than the much sought-after CMB B-mode signal. The absolute calibration of the polarisation angle is particularly important in this sense, as any associated error will end up in a leakage from the much larger E modes into B modes. The Crab nebula (Tau A), with its bright microwave synchrotron emission, is one of the few objects in the sky that can be used as absolute polarisation calibrators. In this communication, we review the best current constraints on its polarisation angle from 23 to 353 GHz, at typical angular scales for CMB observations, from WMAP, IRAM XPOL, Planck and NIKA data. We will show that these polarisation angle measurements are compatible with a constant angle and we will present a study of the uncertainty on this mean angle, making different considerations on how to combine the individual measurement errors. For each of the cases, the potential impact on the CMB B-mode spectrum will be explored.

arXiv commentTo appear in the proceedings of the international conference entitled mm Universe @ NIKA2, Grenoble (France), June 2019, EPJ Web of conferences

References in corpus (13)

• Planck 2015 results. XIII. Cosmological parameters
• Quintessence and the Rest of the World
• Cosmological Signature of New Parity-Violating Interactions
• BICEP2 / Keck Array x: Constraints on Primordial Gravitational Waves using Planck, WMAP, and New BICEP2/Keck Observations through the 2015 Season
• Planck intermediate results. XLVI. Reduction of large-scale systematic effects in HFI polarization maps and estimation of the reionization optical depth
• Planck intermediate results. XXX. The angular power spectrum of polarized dust emission at intermediate and high Galactic latitudes
• Planck 2015 results. XIX. Constraints on primordial magnetic fields
• Planck 2015 results. XXVI. The Second Planck Catalogue of Compact Sources
• Planck pre-launch status: High Frequency Instrument polarization calibration
• CMB Polarization Systematics, Cosmological Birefringence and the Gravitational Waves Background
• POLOCALC: a Novel Method to Measure the Absolute Polarization Orientation of the Cosmic Microwave Background
• A CubeSat for Calibrating Ground-Based and Sub-Orbital Millimeter-Wave Polarimeters (CalSat)
• NIKA 150 GHz polarization observations of the Crab nebula and its spectral energy distribution

Cited by in corpus (7)

• Planck 2018 results. XII. Galactic astrophysics using polarized dust emission
• Searching for Anisotropic Cosmic Birefringence with Polarization Data from SPTpol
• The large scale polarization explorer (LSPE) for CMB measurements: performance forecast
• The Simons Observatory: gain, bandpass and polarization-angle calibration requirements for B-mode searches
• Determination of Polarization Angles in CMB Experiments and Application to CMB Component Separation Analyses
• Cosmology Large Angular Scale Surveyor (CLASS): 90 GHz Telescope Pointing, Beam Profile, Window Function, and Polarization Performance
• Polarization angle requirements for CMB B-mode experiments. Application to the LiteBIRD satellite