COSMOGLOBE DR1 results

II. Constraints on isotropic cosmic birefringence from reprocessed WMAP and Planck LFI data

¹ Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029 Blindern, 0315 Oslo, Norway
e-mail: j.r.eskilt@astro.uio.no
² Imperial Centre for Inference and Cosmology, Department of Physics, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ, UK
³ Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria, 16, Milano, Italy
⁴ Instituto de Física, Universidade de São Paulo, C.P. 66318, CEP: 05315-970, São Paulo, Brazil
⁵ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08540, USA
⁶ Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T1Z1, Canada
⁷ David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
⁸ Dunlap Institute for Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
⁹ Waterloo Centre for Astrophysics, University of Waterloo, Waterloo, ON N2L 3G1, Canada
¹⁰ Department of Physics, Indian Institute of Technology (BHU), Varanasi 221005, India
¹¹ Indian Institute of Astrophysics, Koramangala II Block, Bangalore 560034, India
¹² Laboratoire Astroparticule et Cosmologie (APC), Université Paris, CNRS, 10 rue Alice Domon et Léonie Duquet, 75013 Paris, France
¹³ Department of Physics, University of California, Berkeley, Berkeley, CA 94720, USA

Received: 7 May 2023
Accepted: 27 June 2023

Abstract

Cosmic birefringence is a parity-violating effect that might have rotated the plane of the linearly polarized light of the cosmic microwave background (CMB) by an angle β since its emission. This angle has recently been measured to be nonzero at a statistical significance of 3.6σ in the official Planck PR4 and 9-year WMAP data. In this work, we constrain β using the reprocessed BEYONDPLANCK LFI and COSMOGLOBE DR1 WMAP polarization maps. These novel maps have both lower systematic residuals and a more complete error description than the corresponding official products. Foreground EB correlations could bias measurements of β, and while thermal dust EB emission has been argued to be statistically nonzero, no evidence for synchrotron EB power has been reported. Unlike the dust-dominated Planck HFI maps, the majority of the LFI and WMAP polarization maps are instead dominated by synchrotron emission. Simultaneously constraining β and the polarization miscalibration angle, α, of each channel, we find a best-fit value of β = 0.35° ±0.70° with LFI and WMAP data only. When including the Planck HFI PR4 maps, but fitting β separately for dust-dominated, β_{> 70 GHz}, and synchrotron-dominated channels, β_≤70 GHz, we find β_≤70 GHz = 0.53° ±0.28°. This differs from zero with a statistical significance of 1.9σ, and the main contribution to this value comes from the LFI 70 GHz channel. While the statistical significances of these results are low on their own, the measurement derived from the LFI and WMAP synchrotron-dominated maps agrees with the previously reported HFI-dominated constraints, despite the very different astrophysical and instrumental systematics involved in all these experiments.