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Do baryons trace dark matter in the early universe?
Daniel Grin1, Olivier Doré, Marc Kamionkowski
1School of Natural Sciences, Institute for Advanced Study, Princeton, New Jersey 08540, USA.
Physical Review Letters
|January 17, 2012
Summary
Large-amplitude compensated isocurvature perturbations (CIPs) can exist and influence cosmic microwave background (CMB) observations. These perturbations create detectable correlations and B modes in CMB data, offering new avenues for cosmological research.
Area of Science:
- Cosmology
- Astrophysics
- Particle Physics
Background:
- Large-amplitude baryon-density perturbations require compensation by dark-matter perturbations to maintain a constant total density.
- Primordial abundances and galaxy cluster observations constrain these compensated isocurvature perturbations (CIPs) to amplitudes as large as 10%.
Purpose of the Study:
- To investigate the impact of compensated isocurvature perturbations (CIPs) on the cosmic microwave background (CMB) power spectrum.
- To introduce methods for detecting and measuring the effects of CIPs in CMB temperature and polarization maps.
Main Methods:
- Calculating the magnitude of CIP-induced modulations in the CMB power spectrum.
- Analyzing correlations between spherical-harmonic coefficients in CMB temperature and polarization data.
- Identifying induced polarization B modes as a signature of CIPs.
Main Results:
- CIPs modulate the CMB power spectrum as a function of position on the sky.
- CIPs induce correlations between different spherical-harmonic coefficients in CMB maps.
- CIPs generate polarization B modes, providing a unique observable.
Conclusions:
- CIPs with amplitudes up to 10% are theoretically possible and can be probed with existing large-scale CMB data.
- Future CMB experiments offer an order-of-magnitude improvement in sensitivity to CIPs.
- Detection of CIPs would provide crucial insights into early universe physics and cosmology.
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