The Simons Observatory: impact of bandpass, polarization angle and calibration uncertainties on small-scale power spectrum analysis

Abstract

We study the effects due to mismatches in passbands, polarization angles, and temperature and polarization calibrations in the context of the upcoming cosmic microwave background experiment Simons Observatory (SO). Using the SO multi-frequency likelihood, we estimate the bias and the degradation of constraining power in cosmological and astrophysical foreground parameters assuming different levels of knowledge of the instrumental effects. We find that incorrect but reasonable assumptions about the values of all the systematics examined here can have significant effects on cosmological analyses, hence requiring marginalization approaches at the likelihood level. When doing so, we find that the most relevant effect is due to bandpass shifts. When marginalizing over them, the posteriors of parameters describing astrophysical microwave foregrounds (such as radio point sources or dust) get degraded, while cosmological parameters constraints are not significantly affected. Marginalization over polarization angles with up to 0.25${}^{\circ }$ uncertainty causes an irrelevant bias $\lesssim 0.05\sigma$ in all parameters. Marginalization over calibration factors in polarization broadens the constraints on the effective number of relativistic degrees of freedom $N_{\mathrm{eff}}$ by a factor 1.2, interpreted here as a proxy parameter for non standard model physics targeted by high-resolution CMB measurements.

61 pages (27 of which are appendices), 26 figures, 12 tables. (Replacement to update the acknowledgments)

References in corpus (13)

• Array Programming with NumPy
• The Cosmic Linear Anisotropy Solving System (CLASS) I: Overview
• CMB-S4 Science Case, Reference Design, and Project Plan
• COSMOPOWER: emulating cosmological power spectra for accelerated Bayesian inference from next-generation surveys
• Self-regulated reionization
• The Atacama Cosmology Telescope: Constraints on Pre-Recombination Early Dark Energy
• CMB Polarization can constrain cosmology better than CMB temperature
• Inflation: Theory and Observations
• Neutrino Mass from Cosmology: Probing Physics Beyond the Standard Model
• The Atacama Cosmology Telescope: limits on dark matter-baryon interactions from DR4 power spectra
• Fast computation of angular power spectra and covariances of high-resolution cosmic microwave background maps using the Toeplitz approximation
• Snowmass2021 Cosmic Frontier: Cosmic Microwave Background Measurements White Paper
• Snowmass2021 Cosmic Frontier White Paper: Probing dark matter with small-scale astrophysical observations

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