scholarly journals PRISM: Sparse recovery of the primordial spectrum from WMAP9 and Planck datasets

2014 ◽  
Vol 10 (S306) ◽  
pp. 60-63
Author(s):  
P. Paykari ◽  
F. Lanusse ◽  
J.-L. Starck ◽  
F. Sureau ◽  
J. Bobin
Keyword(s):  
Inverse Problem ◽  
Power Spectrum ◽  
Structure Formation ◽  
Simulated Data ◽  
Inversion Method ◽  
Formation Mechanisms ◽  
Parametric Approach ◽  
Microwave Background ◽  
Scale Invariant ◽  
Primordial Power Spectrum

AbstractThe primordial power spectrum is an indirect probe of inflation or other structure-formation mechanisms. We introduce a new method, named PRISM, to estimate this spectrum from the empirical cosmic microwave background (CMB) power spectrum. This is a sparsity-based inversion method, which leverages a sparsity prior on features in the primordial spectrum in a wavelet dictionary to regularise the inverse problem. This non-parametric approach is able to reconstruct the global shape as well as localised features of the primordial spectrum accurately and proves to be robust for detecting deviations from the currently favoured scale-invariant spectrum. We investigate the strength of this method on a set of WMAP nine-year simulated data for three types of primordial spectra and then process the WMAP nine-year data as well as the Planck PR1 data. We find no significant departures from a near scale-invariant spectrum.

scholarly journals EARLY UNIVERSE SOURCES FOR CMB NON-GAUSSIANITY

2002 ◽  
Vol 17 (29) ◽  
pp. 4273-4280
Author(s):  
ALEJANDRO GANGUI
Keyword(s):  
Power Spectrum ◽  
Cosmic Microwave Background ◽  
Early Universe ◽  
Microwave Background ◽  
Scale Invariant ◽  
Invariant Model ◽  
Primordial Power Spectrum ◽  
Initial States ◽  
Non Gaussian ◽  
Inflationary Models

In the framework of inflationary models with non-vacuum initial states for cosmological perturbations, we study non-Gaussian signatures on the cosmic microwave background (CMB) radiation produced by a broken-scale-invariant model which incorporates a feature at a privileged scale in the primordial power spectrum.

scholarly journals HIGGS BOSON IN RG RUNNING INFLATIONARY COSMOLOGY

2012 ◽  
Vol 21 (14) ◽  
pp. 1250094 ◽  
Author(s):  
YI-FU CAI ◽  
DAMIEN A. EASSON
Keyword(s):  
Higgs Boson ◽  
Power Spectrum ◽  
Higgs Mass ◽  
Hadron Collider ◽  
Higgs Sector ◽  
Inflationary Cosmology ◽  
Microwave Background ◽  
Scale Invariant ◽  
Primordial Power Spectrum ◽  
The Standard Model

An intriguing hypothesis is that gravity may be nonperturbatively renormalizable via the notion of asymptotic safety (AS). We show that the Higgs sector of the standard model (SM) minimally coupled to asymptotically safe gravity can generate the observed near scale-invariant spectrum of the Cosmic Microwave Background through the curvaton mechanism. The resulting primordial power spectrum places an upper bound (CMB) on the Higgs mass, which for finely tuned values of the curvaton parameters, is compatible with the recently released Large Hadron Collider (LHC) data.

scholarly journals Structure Constraints from Large Angle CMB Anisotropies

1992 ◽  
Vol 9 ◽  
pp. 319-321
Author(s):  
J. Richard Bond
Keyword(s):  
Correlation Function ◽  
Structure Formation ◽  
Large Distance ◽  
Large Angle ◽  
Microwave Background ◽  
Scale Invariant ◽  
Intermediate Angle ◽  
History Of ◽  
Adiabatic Fluctuations ◽  
The Universe

Constraints on models of cosmic structure formation that can be drawn from current limits on large angle microwave background anisotropies are now competitive with those from recent small and intermediate angle experiments and are relatively insensitive to the reheating history of the Universe. Here I give limits on Gaussian scale invariant adiabatic fluctuations and describe the role that the large angle results play in constraining models with enhanced large distance galaxy clustering power inferred from correlation function measurements is described.

scholarly journals Reconstructing the Primordial Power Spectrum

2005 ◽  
Vol 216 ◽  
pp. 28-34
Author(s):  
S. L. Bridle ◽  
A. M. Lewis ◽  
J. Weller ◽  
G. Efstathiou
Keyword(s):  
Power Spectrum ◽  
Spectral Index ◽  
Large Scale ◽  
Cosmological Parameters ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Microwave Background ◽  
Primordial Power Spectrum ◽  
Initial Spectrum ◽  
Redshift Survey ◽  
Cosmic Microwave Background Data

We reconstruct the shape of the primordial power spectrum from the latest cosmic microwave background data, including the new results from the Wilkinson Microwave Anisotropy Probe (WMAP), and large scale structure data from the two degree field galaxy redshift survey (2dFGRS). We discuss two parameterizations taking into account the uncertainties in four cosmological parameters. First we parameterize the initial spectrum by a tilt and a running spectral index, finding marginal evidence for a running spectral index only if the first three WMAP multipoles (ℓ = 2, 3, 4) are included in the analysis. Secondly, to investigate further the low CMB large scale power, we modify the conventional power-law spectrum by introducing a scale above which there is no power. We find a preferred position of the cut at kc ∼ 3 × 10--4 Mpc--1 although kc = 0 (no cut) is not ruled out.

scholarly journals TESTING FOR FEATURES IN THE PRIMORDIAL POWER SPECTRUM

2009 ◽  
Vol 18 (12) ◽  
pp. 1863-1888 ◽  
Author(s):  
LOISON HOI ◽  
JAMES M. CLINE
Keyword(s):  
Power Spectrum ◽  
Nonlinear Evolution ◽  
Angular Spectrum ◽  
Theoretical Models ◽  
Scale Invariant ◽  
Primordial Power Spectrum ◽  
High K ◽  
Blue Component ◽  
Hybrid Inflation ◽  
Second Peak

Well-known causality arguments show that events occurring during or at the end of inflation, associated with reheating or preheating, could contribute a blue component to the spectrum of primordial curvature perturbations, with the dependence k3. We explore the possibility that they could be observably large in CMB, LSS, and Lyman-α data. We find that a k3 component with a cutoff at some maximum k can modestly improve the fits (Δχ2 = 2.0, 5.4) of the low multipoles (ℓ ~ 10–50) or the second peak (ℓ ~ 540) of the CMB angular spectrum when the three-year WMAP data are used. Moreover, the results from WMAP are consistent with the CBI, ACBAR, 2dFGRS, and SDSS data when they are included in the analysis. Including the SDSS galaxy clustering power spectrum, we find weak positive evidence for the k3 component at the level of Δχ2′ = 2.4, with the caveat that the nonlinear evolution of the power spectrum may not be properly treated in the presence of the k3 distortion. To investigate the high-k regime, we use the Lyman-α forest data (LUQAS, Croft et al., and SDSS Lyman-α); here we find evidence at the level Δχ2′ = 3.8. Considering that there are two additional free parameters in the model, the above results do not give a strong evidence for features; however, they show that surprisingly large bumps are not ruled out. We give constraints on the ratio between the k3 component and the nearly scale-invariant component, r3 < 1.5, over the range of wave numbers 2.3 × 10-3 Mpc -1 < k < 8.2 Mpc -1. We also discuss theoretical models which could lead to the k3 effect, including ordinary hybrid inflation and double D-term inflation models. We show that the well-motivated k3 component is also a good representative of the generic spikelike feature in the primordial perturbation power spectrum.

scholarly journals Early Structure Formation and Reionization in a Cosmological Model with a Running Primordial Power Spectrum

2003 ◽  
Vol 598 (1) ◽  
pp. 73-85 ◽  
Author(s):  
Naoki Yoshida ◽  
Aaron Sokasian ◽  
Lars Hernquist ◽  
Volker Springel
Keyword(s):  
Power Spectrum ◽  
Cosmological Model ◽  
Structure Formation ◽  
Primordial Power Spectrum

scholarly journals STRONG LENSING PROBABILITIES IN A COSMOLOGICAL MODEL WITH A RUNNING PRIMORDIAL POWER SPECTRUM

2005 ◽  
Vol 20 (11) ◽  
pp. 851-859 ◽  
Author(s):  
TONG-JIE ZHANG ◽  
ZHI-LIANG YANG ◽  
XIANG-TAO HE
Keyword(s):  
Power Spectrum ◽  
Cosmological Model ◽  
Spectral Power ◽  
Density Fluctuations ◽  
Wilkinson Microwave Anisotropy Probe ◽  
First Year ◽  
Microwave Background ◽  
Primordial Power Spectrum ◽  
Λcdm Model ◽  
Image Separation

The combination of the first-year Wilkinson Microwave Anisotropy Probe (WMAP) data with other finer scale cosmic microwave background (CMB) experiments (CBI and ACBAR) and two structure formation measurements (2dFGRS and Lyman α forest) suggest a ΛCDM cosmological model with a running spectral power index of primordial density fluctuations. Motivated by this new result on the index of primordial power spectrum, we present the first study on the predicted lensing probabilities of image separation in a spatially flat ΛCDM model with a running spectral index (RSI-ΛCDM model). It is shown that the RSI-ΛCDM model suppresses the predicted lensing probabilities on small splitting angles of less than about 4″ compared with that of standard power-law ΛCDM (PL-ΛCDM) model.

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