PhysRevD.99.043518.pdf (493.29 kB)
Optimal constraints on primordial gravitational waves from the lensed CMB
Version 2 2023-06-12, 09:00
Version 1 2023-06-09, 16:47
journal contribution
posted on 2023-06-12, 09:00 authored by Julien CarronWe demonstrate how to obtain optimal constraints on a primordial gravitational wave component in lensed Cosmic Microwave Background (CMB) data under ideal conditions. We first derive an estimator of the tensorto-scalar ratio, r, by using an error-controlled close approximation to the exact posterior, under the assumption of Gaussian primordial CMB and lensing deflection potential. This combines fast internal iterative lensing reconstruction with optimal recovery of the unlensed CMB. We evaluate its performance on simulated lownoise polarization data targeted at the recombination peak. We carefully demonstrate our r-posterior estimate is optimal and shows no significant bias, making it the most powerful estimator of primordial gravitational waves from the CMB. We compare these constraints to those obtained from B-mode band-power likelihood analyses on the same simulated data, before and after map-level quadratic estimator delensing, and iterative delensing. Internally, iteratively delensed band powers are only slightly less powerful on average (by less than 10%), promising close-to-optimal constraints from a stage IV CMB experiment.
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- Published
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- Published version
Journal
Physical Review DISSN
2470-0010Publisher
American Physical SocietyExternal DOI
Issue
043518Volume
99Page range
1-14Department affiliated with
- Physics and Astronomy Publications
Research groups affiliated with
- Astronomy Centre Publications
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- Yes
Peer reviewed?
- Yes
Legacy Posted Date
2019-02-07First Open Access (FOA) Date
2019-02-07First Compliant Deposit (FCD) Date
2019-02-06Usage metrics
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