Searching for oscillations in the primordial power spectrum with CMB and LSS data

Abstract

Different inflationary models predict oscillatory features in the primordial power spectrum. These can leave an imprint on both the cosmic microwave background (CMB) and the large-scale structure (LSS) of our Universe, that can be searched for with current data. Inspired by the axion-monodromy model of inflation, we search for primordial oscillations that are logarithmic in wavenumber, using both CMB data from the Planck satellite and LSS data from the WiggleZ galaxy survey. We find that, within our search range for the new oscillation parameters (amplitude, frequency and phase), both CMB-only and CMB+LSS data yield the same best-fit oscillation frequency of log 10 ω = 1.5, improving the fit over ΛCDM by ∆χ 2 = −9 and ∆χ 2 = −13 (roughly corresponding to 2σ and 2.8σ significance), respectively. Bayesian evidence for the log-oscillation model versus ΛCDM indicates a very slight preference for the latter. Future CMB and LSS data will further probe this scenario.

Resonant reconciliation of convex-potential inflation models and the Planck data

“…In particular, models of single field inflation with convex potential has been disfavored [1].One of the features of single field slow-roll inflation models is that H does not explicitly appear in expressions for r, n s and these two are only functions of the slow-roll parameters ǫ, η which are given in terms of derivatives of the inflaton potential. This, together with requiring enough number of e-folds of inflation N e (usually N e 60) is the basic fact allowing for ruling out such models.Axion monodromy inflation is among models which has theoretical support and is consistent with the current data [2][3][4][5][6][7][8][9]. This model has a (concave) power-law potential, usually a potential linear in inflaton, plus an oscillatory modulation term.…”

“…Axion monodromy inflation is among models which has theoretical support and is consistent with the current data [2][3][4][5][6][7][8][9]. This model has a (concave) power-law potential, usually a potential linear in inflaton, plus an oscillatory modulation term.…”

“…This model has a (concave) power-law potential, usually a potential linear in inflaton, plus an oscillatory modulation term. The oscillatory part induces cosine-log undulations in the spectral tilt n s and the non-Gaussianity parameter f N L which could be used to restrict these models [8,10].In this paper we employ ideas of monodromy inflation, namely a single field inflation model plus a subdominant oscillatory term and augment the model by the addition of a light scalar field which couples to inflaton through an "oscillatory interaction term" involving cosine of inflaton. As we will argue this can have profound effects on the cosmic perturbation theory of the model, while not backreacting on the inflationary background trajectory.…”

Exploring the CMB power suppression in canonical inflation models

“…difficult (interesting work includes Ref. [23]). We also note that models with non-trivial features in the potential may also give rise to significant non-Gaussianity, which could also rule them out for independent reasons, so this is another important constraint to satisfy.…”

Thermal loop effects on large-scale curvature perturbation in the Higgs inflation

“…Together with the composition of the Universe after reheating and the late-time cosmological processes, we can reconstruct the angular power spectra D T T of the CMB and compare it with that determined by the correlation function of the CMB temperature anisotropies. Investigating the primordial power spectrum thus facilitates the constraints on the physics of inflation [37][38][39][40][41][42][43]. In this section, we examine how the formalism of the finite-temperature loop corrections in the EF discussed in section 3 can affect the dynamics of the inflaton χ and the primordial power spectrum of the quantum perturbation during the inflation.…”