In the curvaton model, an energetically sub-dominant field (the curvaton) during inflation eventually begins to redshift as matter, allowing it and its decay products to later dominate the overall primordial density fluctuation (overtaking that caused by fluctuations in the inflaton itself). In this work, Tristan Smith and I systematically probed and limited the curvaton parameter […]
One interesting feature of compensated isocurvature perturbations (CIPs) is that they have a similar effect on CMB power spectra to weak lensing of the CMB. CIPs are fluctuations in the relative number densities of dark matter and baryons. In this work (led by Johns Hopkins graduate student Julian B. Muñoz under my mentorship & supervised […]
Compensated isocurvature perturbations (CIPs) are fluctuations in the relative density of baryons and cold dark matter (CDM) at fixed total matter density, which are detectable using CMB data as a result of a spatially varying sound speed in the baryon-photon plasma. In this work, graduate student Chen He (mentored by me & supervised by Prof. […]
Isocurvature perturbations are fluctuations in the relative number densities of particles at constant total density. Like adiabatic (or total density) fluctuations, primordial isocurvature perturbations will excite acoustic waves in the baryon-photon plasma. Jens Chluba and I computed the spectral distortions (deviations of the spatially averaged CMB from a perfect blackbody) generated when these acoustic waves […]
Working with Duncan Hanson,we used the WMAP 9-year maps to search for evidence of compensated isocurvature perturbations (CIPs) using the techniques outlined in arXiv:1107.5047. We find that baryons do trace dark matter at the ~10% level (expressed as a limit on the CIP amplitude). Results published in arXiv:1306.4319 (Phys. Rev. D 89, 023006). Collaborators: Duncan […]
Unlike isocurvature perturbations between photons and neutrinos, CDM, or baryons, isocurvature perturbations between dark matter and baryons are surprisingly poorly constrained. In this work, we show that such perturbations do have observable effects on the CMB due to higher-order effects that induce off-diagonal correlations and non-Gaussianity in the CMB. Results published in arXiv:1107.5047 (Phys. Rev. […]
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