CMB constraints on principal components of the inflaton potential
Abstract
We place functional constraints on the shape of the inflaton potential from the cosmic microwave background through a variant of the generalized slowroll approximation that allows large amplitude, rapidly changing deviations from scalefree conditions. Employing a principal component decomposition of the source function G^{'}≈3(V^{'}/V)^{2}2V^{''}/V and keeping only those measured to better than 10% results in 5 nearly independent Gaussian constraints that may be used to test any singlefield inflationary model where such deviations are expected. The first component implies <3% variations at the 100 Mpc scale. One component shows a 95% CL preference for deviations around the 300 Mpc scale at the ∼10% level but the global significance is reduced considering the 5 components examined. This deviation also requires a change in the cold dark matter density which in a flat ΛCDM model is disfavored by current supernova and Hubble constant data and can be tested with future polarization or high multipole temperature data. Its impact resembles a local running of the tilt from multipoles 30800 but is only marginally consistent with a constant running beyond this range. For this analysis, we have implemented a ∼40× faster WMAP7 likelihood method which we have made publicly available.
 Publication:

Physical Review D
 Pub Date:
 August 2010
 DOI:
 10.1103/PhysRevD.82.043513
 arXiv:
 arXiv:1007.0215
 Bibcode:
 2010PhRvD..82d3513D
 Keywords:

 98.80.Cq;
 98.70.Vc;
 98.80.Es;
 Particletheory and fieldtheory models of the early Universe;
 Background radiations;
 Observational cosmology;
 Astrophysics  Cosmology and Extragalactic Astrophysics;
 High Energy Physics  Phenomenology
 EPrint:
 12 pages, 14 figures, submitted to Phys.Rev.D. Optimized WMAP7 likelihood code and principal component functions of the GSR source function available at http://background.uchicago.edu/wmap_fast/