Updated constraints on neutrino-sustained primordial vector modes imply magnetic fields too weak to seed observations and cannot reproduce the EB power spectrum while satisfying parity-even limits.
Cosmic Birefringence from the Atacama Cosmology Telescope Data Release 6
3 Pith papers cite this work. Polarity classification is still indexing.
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abstract
The polarized light of the cosmic microwave background is sensitive to new physics that violates parity symmetry. For example, the interaction of photons with the fields of elusive dark matter and dark energy could cause a uniform rotation of the plane of linear polarization across the sky, an effect known as cosmic birefringence. We extract the cosmological rotation angle, $\beta$, using Bayesian analysis of parity-violating correlations, $EB$ and $TB$, of polarization data from the Atacama Cosmology Telescope (ACT) Data Release 6. We use prior probabilities for instrumental miscalibration angles derived from the optics model for the ACT telescope and instruments, and marginalize over a residual intensity-to-polarization leakage. We measure $\beta = 0.215^\circ\pm 0.074^\circ$ (68\% confidence level), which excludes $\beta=0$ with a statistical significance of $2.9\sigma$. Although there remain systematics in the ACT data that are not understood and do not allow us to draw strong cosmological conclusions, this result is consistent with previous independent results from the WMAP and Planck missions. It is suggestive that independent data sets and analyses using different methodologies have yielded the same sign and comparable magnitudes for $\beta$.
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Including spectral running α_s, β_s and self-interacting dark radiation relaxes the ACT DR6 bound on ΔN_eff to <0.58 and lowers the Hubble tension to 2.2σ with three extra parameters.
The COSMOCal collaboration reports the scientific motivation, instrument development status, and March 2026 ground calibration campaign results for a planned geostationary polarized calibrator for CMB telescopes.
citing papers explorer
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Revisiting constraints on primordial vector modes and implications for sourced magnetic fields and observed $EB$ power spectrum
Updated constraints on neutrino-sustained primordial vector modes imply magnetic fields too weak to seed observations and cannot reproduce the EB power spectrum while satisfying parity-even limits.
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The End of the First Act: Spectral Running, Interacting Dark Radiation, and the Hubble Tension in Light of ACT DR6 Data
Including spectral running α_s, β_s and self-interacting dark radiation relaxes the ACT DR6 bound on ΔN_eff to <0.58 and lowers the Hubble tension to 2.2σ with three extra parameters.
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Status of the COSmological Microwave Observations CALibrator
The COSMOCal collaboration reports the scientific motivation, instrument development status, and March 2026 ground calibration campaign results for a planned geostationary polarized calibrator for CMB telescopes.