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How to derotate the cosmic microwave background polarization
1California Institute of Technology, Mail Code 130-33, Pasadena, California 91125, USA.
Physical Review Letters
|April 28, 2009
Summary
Rotation of cosmic microwave background polarization can create B-modes. Measuring higher-order correlations can reconstruct this rotation angle, distinguishing it from primordial B-modes and cosmic shear effects.
Area of Science:
- Cosmology
- Astrophysics
- Observational Astronomy
Background:
- The cosmic microwave background (CMB) is a key probe of the early universe.
- CMB polarization contains information about cosmological parameters and early universe physics.
- Frequency-independent rotation of CMB linear polarization can mimic or mask primordial B-modes.
Purpose of the Study:
- To develop a method for distinguishing between primordial B-modes and those induced by polarization rotation.
- To reconstruct the sky-dependent rotation angle of CMB polarization.
- To differentiate rotation-induced B-modes from those caused by cosmic shear.
Main Methods:
- Analysis of higher-order correlation functions of CMB polarization.
- Specifically, measuring TE, EE, EB, and TB correlations.
- Geometric distinction of rotation effects from cosmic shear.
Main Results:
- A technique is presented to measure the rotation angle of CMB polarization across the sky.
- This method allows for the separation of rotation-induced B-modes from primordial B-modes.
- The geometric signature of rotation effects can be identified and distinguished from cosmic shear.
Conclusions:
- Higher-order CMB correlation measurements offer a powerful tool to probe polarization rotation.
- This technique is crucial for accurately detecting primordial B-modes, a signature of cosmic inflation.
- The method provides a way to disentangle foreground or instrumental effects from fundamental cosmological signals.
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