Featuring the primordial power spectrum: new constraints on interrupted slow-roll from CMB and LRG data

Abstract

Using the most recent data from the WMAP, ACT and SPT experiments, we update the constraints on models with oscillatory features in the primordial power spectrum of scalar perturbations. This kind of features can appear in models of inflation where slow-roll is interrupted, like multifield models. We also derive constraints for the case in which, in addition to cosmic microwave observations, we also consider the data on the spectrum of luminous red galaxies from the 7th SDSS catalog, and the SNIa Union Compilation 2 data. We have found that: (i) considering a model with features in the primordial power spectrum increases the agreement with data with the respect of the featureless "vanilla" LCDM model by Delta(chi^2) ~ 7; (ii) the uncertainty on the determination of the standard parameters is not degraded when features are included; (iii) the best fit for the features model locates the step in the primordial spectrum at a scale k ~ 0.005 Mpc^-1, corresponding to the scale where the outliers in the WMAP7 data at ell=22 and ell=40 are located.; (iv) a distinct, albeit less statistically significant peak is present in the likelihood at smaller scales, with a Delta(chi^2) ~ 3.5, whose presence might be related to the WMAP7 preference for a negative value of the running of the scalar spectral index parameter; (v) the inclusion of the LRG-7 data do not change significantly the best fit model, but allows to better constrain the amplitude of the oscillations.

10 pages, 8 figures

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• Localized correlated features in the CMB power spectrum and primordial bispectrum from a transient reduction in the speed of sound
• Updating constraints on inflationary features in the primordial power spectrum with the Planck data
• Probing Two-Field Open Inflation by Resonant Signals in Correlation Functions
• Searching for primordial localized features with CMB and LSS spectra
• Searching for features of a string-inspired inflationary model with cosmological observations
• Changes in the halo formation rates due to features in the primordial spectrum
• Bayesian analysis of inflationary features in Planck and SDSS data
• Reconciling low multipole anomalies and reheating in single field inflationary models
• The MESS of cosmological perturbations
• Simultaneous effect of Modified Gravity and Primordial Non-Gaussianity in Large Scale Structure Observations
• Primordial Non-Gaussianities of inflationary step-like models