A foreground-marginalized 'BK-lite' likelihood for the tensor-to-scalar ratio ...

• Main Authors: Prince, Heather, Calabrese, Erminia, Dunkley, Jo
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: arXiv 2024
• Subjects: Cosmology and Nongalactic Astrophysics astro-ph.CO; FOS Physical sciences; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.2403.00085; https://arxiv.org/abs/2403.00085

The current limit on the tensor-to-scalar ratio from the BICEP/Keck Collaboration (with r<0.036 at 95% confidence) puts pressure on early universe models, with less than 10% of the error on r attributed to uncertainty in Galactic foregrounds. We use the BICEP/Keck BK18 public multi-frequency likelihood to test some further assumptions made in the foreground modeling, finding little impact on the estimate for r. We then estimate foreground-marginalized cosmic microwave background (CMB) B-mode polarization bandpowers. We fit them with a multivariate offset-lognormal distribution and construct a marginalized 'BK-lite' likelihood for the CMB B-mode spectrum with no nuisance parameters, serving as a method demonstration for future analyses of small sky regions, for example from the South Pole Observatory or CMB-S4. ...