scholarly journals Inflation story: slow-roll and beyond

2021 ◽  
Vol 2021 (12) ◽  
pp. 038
Author(s):  
Dhiraj Kumar Hazra ◽  
Daniela Paoletti ◽  
Ivan Debono ◽  
Arman Shafieloo ◽  
George F. Smoot ◽  
...  
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Microwave Background ◽  
Angular Power Spectrum ◽  
Slow Roll ◽  
Primordial Power Spectrum ◽  
Cosmic Microwave Background Temperature ◽  
Scale Temperature ◽  
Temperature Polarization ◽  
Background Temperature

Abstract We present constraints on inflationary dynamics and features in the primordial power spectrum of scalar perturbations using the Cosmic Microwave Background temperature, polarization data from Planck 2018 data release and updated likelihoods. We constrain the slow-roll dynamics using Hilltop Quartic Potential and Starobinsky R + R 2 model in the Einstein frame using the Planck 2018 binned Plik likelihood. Using the Hilltop as base potential, we construct Whipped Inflation potential to introduce suppression in the scalar power spectrum at large angular scales. We notice marginal (68% C.L.) preference of suppression from the large scale temperature angular power spectrum. However, large-scale E-mode likelihood based on high frequency instrument cross spectrum, does not support this suppression and in the combined data the preference towards the suppression becomes negligible. Based on the Hilltop and Starobinsky model, we construct the Wiggly Whipped Inflation potentials to introduce oscillatory features along with the suppression. We use unbinned data from the recently released CamSpec v12.5 likelihood which updates Planck 2018 results. We compare the Bayesian evidences of the feature models with their baseline slow-roll potentials. We find that the complete slow-roll baseline potential is moderately preferred against potentials which generate features. Compared to Planck 2015 PlikHM bin1 likelihood, we find that the significance of sharp features has decreased owing to the updates in the data analysis pipeline. We also compute the bispectra for the best fit candidates obtained from our analysis.

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 Cosmology with the cosmic microwave background temperature-polarization correlation

2017 ◽  
Vol 602 ◽  
pp. A41 ◽  
Author(s):  
F. Couchot ◽  
S. Henrot-Versillé ◽  
O. Perdereau ◽  
S. Plaszczynski ◽  
B. Rouillé d’Orfeuil ◽  
...  
Keyword(s):  
Cosmic Microwave Background ◽  
Cosmological Parameters ◽  
Power Spectra ◽  
Microwave Background ◽  
Instrumental Noise ◽  
Cosmic Microwave Background Temperature ◽  
Temperature Polarization ◽  
Background Temperature ◽  
The Impact ◽  
Polarization Correlation

We demonstrate that the cosmic microwave background (CMB) temperature-polarization cross-correlation provides accurate and robust constraints on cosmological parameters. We compare them with the results from temperature or polarization and investigate the impact of foregrounds, cosmic variance, and instrumental noise. This analysis makes use of the Planck high-ℓ HiLLiPOP likelihood based on angular power spectra, which takes into account systematics from the instrument and foreground residuals directly modelled using Planck measurements. The temperature-polarization correlation (TE) spectrum is less contaminated by astrophysical emissions than the temperature power spectrum (TT), allowing constraints that are less sensitive to foreground uncertainties to be derived. For ΛCDM parameters, TE gives very competitive results compared to TT. For basic ΛCDM model extensions (such as AL, ∑mν, or Neff), it is still limited by the instrumental noise level in the polarization maps.

scholarly journals Constraints on features in the inflationary potential from future Euclid data

2020 ◽  
Vol 496 (3) ◽  
pp. 3448-3468
Author(s):  
Ivan Debono ◽  
Dhiraj Kumar Hazra ◽  
Arman Shafieloo ◽  
George F Smoot ◽  
Alexei A Starobinsky
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Large Scale ◽  
Strong Support ◽  
Power Spectra ◽  
Spectral Amplitude ◽  
Microwave Background ◽  
Slow Roll ◽  
Primordial Power Spectrum ◽  
Small Scales

ABSTRACT With Planck cosmic microwave background observations, we established the spectral amplitude and tilt of the primordial power spectrum. Evidence of a red spectral tilt (ns = 0.96) at 8σ provides strong support for the inflationary mechanism, especially the slow roll of the effective scalar field in its nearly flat potential as the generator of scalar primordial perturbations. With the next generation of large-scale structure surveys, we expect to probe primordial physics beyond the overall shape and amplitude of the main, smooth, and slowly changing part of the inflaton potential. Using the specifications for the upcoming Euclid survey, we investigate to what extent we can constrain the inflation potential beyond its established slow-roll behaviour. We provide robust forecasts with Euclid and Planck mock data from nine fiducial power spectra that contain suppression and wiggles at different cosmological scales, using the Wiggly Whipped Inflation (WWI) framework to generate these features in the primordial spectrum. We include both Euclid cosmic shear and galaxy clustering, with a conservative cut-off for non-linear scales. Using Markov chain Monte Carlo simulations, we obtain an improvement in constraints in the WWI potential, as well an improvement for the background cosmology parameters. We find that apart from improving the constraints on the overall scale of the inflationary potential by 40–50 per cent, we can also identify oscillations in the primordial spectrum that are present within intermediate to small scales ($k\sim 0.01\!-\!0.2\, \mathrm{Mpc^{-1}}$).

First Year WMAP Observations

2005 ◽  
Vol 216 ◽  
pp. 18-27
Author(s):  
C. L. Bennett
Keyword(s):  
Power Spectrum ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Large Angle ◽  
Baryon Density ◽  
First Year ◽  
Microwave Background ◽  
Sky Survey ◽  
Temperature Polarization ◽  
Best Fit

The results of the first year WMAP sky survey are full sky microwave maps in five frequency bands from 23 to 94 GHz. Calibration errors are < 0.5% and the low systematic error level is well specified. The cosmic microwave background (CMB) is separated from the foregrounds using the multifrequency data. The 2 ≤ l ≤ 900 anisotropy power spectrum is cosmic variance limited for l < 354 with a signal-to-noise ratio >1 per mode to l = 658. The temperature-polarization cross-power spectrum reveals both acoustic features and a large angle correlation from reionization. The optical depth of reionization is τ = 0.17 ± 0.04. A best-fit cosmological model to the CMB and other measures of large scale structure works remarkably well with only a few parameters. The age of the best-fit universe is t0 = 13.7 ± 0.2 Gyr old. The matter density is Ωmh2 = 0.135+0.008--0.009, the baryon density is Ωbh2 = 0.0224 ± 0.0009, and the total mass-energy of the universe is Ωtot = 1.02±0.02. For WMAP data alone, ns = 0.99 ± 0.04. The lack of CMB fluctuation power on the largest angular scales reported by COBE and confirmed by WMAP is intriguing. WMAP continues to operate, so results will improve.

scholarly journals Constraints on gravity on cosmic scales with upcoming large-scale structure surveys

2011 ◽  
Vol 369 (1957) ◽  
pp. 4976-4984
Author(s):  
Rachel Bean
Keyword(s):  
Figure Of Merit ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Weak Lensing ◽  
Microwave Background ◽  
Photometric Redshift ◽  
Cosmic Microwave Background Temperature ◽  
Background Temperature ◽  
Galaxy Bias

We consider how upcoming, prospective large-scale structure surveys, measuring galaxy weak lensing and position in tandem with the cosmic microwave background temperature anisotropies, constrain cosmic scale modifications to general relativity. In such theories, both the homogeneous expansion history and the growth of large-scale structure can have signatures of the modification. We consider an equation of state figure of merit parameter, and introduce an analogous figure of merit parameter for modified gravity, to quantify the relative constraints. We discuss how assumptions about the presence of astrophysical and instrumental systematics such as galaxy bias, intrinsic alignments, weak lensing shear calibration uncertainties and photometric redshift offsets can impact the prospective dark energy constraints.

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