Search Publications
Witnessing the reionization history using Cosmic Microwave Background observation from Planck
Hazra, Dhiraj Kumar; Smoot, George F.
We constrain the history of reionization using the data from Planck 2015 Cosmic Microwave Background (CMB) temperature and polarization anisotropy observations. We also use prior constraints on the reionization history at redshifts ~7-8 obtained from Lyman-α emission observations. Using the free electron fractions at different redshifts as free pa…
Planck satellite constraints on pseudo-Nambu-Goldstone boson quintessence
Liddle, Andrew R.; Smer-Barreto, Vanessa
The pseudo-Nambu-Goldstone Boson (PNGB) potential, defined through the amplitude M4 and width f of its characteristic potential V(phi) = M4[1 + cos(phi/f)], is one of the best-suited models for the study of thawing quintessence. We analyse its present observational constraints by direct numerical solution of the scalar field …
CMB and matter power spectra with non-linear dark-sector interactions
vom Marttens, R. F.; Casarini, L.; Hipólito-Ricaldi, W. S. +1 more
An interaction between dark matter and dark energy, proportional to the product of their energy densities, results in a scaling behavior of the ratio of these densities with respect to the scale factor of the Robertson-Walker metric. This gives rise to a class of cosmological models which deviate from the standard model in an analytically tractabl…
General quadrupolar statistical anisotropy: Planck limits
Ramazanov, S.; Rubtsov, G.; Thorsrud, M. +1 more
Several early Universe scenarios predict a direction-dependent spectrum of primordial curvature perturbations. This translates into the violation of the statistical isotropy of cosmic microwave background radiation. Previous searches for statistical anisotropy mainly focussed on a quadrupolar direction-dependence characterised by a single multipol…
A non-parametric consistency test of the ΛCDM model with Planck CMB data
Shafieloo, Arman; Aghamousa, Amir; Hamann, Jan
Non-parametric reconstruction methods, such as Gaussian process (GP) regression, provide a model-independent way of estimating an underlying function and its uncertainty from noisy data. We demonstrate how GP-reconstruction can be used as a consistency test between a given data set and a specific model by looking for structures in the residuals of…
On the impact of large angle CMB polarization data on cosmological parameters
Gerbino, Martina; Salvati, Laura; Burigana, Carlo +6 more
We study the impact of the large-angle CMB polarization datasets publicly released by the WMAP and Planck satellites on the estimation of cosmological parameters of the ΛCDM model. To complement large-angle polarization, we consider the high resolution (or "high-l") CMB datasets from either WMAP or Planck as well as CMB lensing as traced by Planck…
Probing the primordial universe with gravitational waves detectors
Liu, Zhi-Guo; Piao, Yun-Song; Wang, Yu-Tong +1 more
The spectrum of primordial gravitational waves (GWs), especially its tilt nT, carries significant information about the primordial universe. Combining recent aLIGO and Planck2015+BK14 data, we find that the current limit is nT=0.016+0.614-0.989 at 95% C.L. We also estimate the impacts of Einstein Telesco…
Consistency of the Planck CMB data and ΛCDM cosmology
Hazra, Dhiraj Kumar; Shafieloo, Arman
We test the consistency between Planck temperature and polarization power spectra and the concordance model of Λ Cold Dark Matter cosmology (ΛCDM) within the framework of Crossing statistics. We find that Planck TT best fit ΛCDM power spectrum is completely consistent with EE power spectrum data while EE best fit ΛCDM power spectrum is not consist…
Planck limits on non-canonical generalizations of large-field inflation models
Stein, Nina K.; Kinney, William H.
In this paper, we consider two case examples of Dirac-Born-Infeld (DBI) generalizations of canonical large-field inflation models, characterized by a reduced sound speed, cS < 1. The reduced speed of sound lowers the tensor-scalar ratio, improving the fit of the models to the data, but increases the equilateral-mode non-Gaussianity, …
Constraining dynamical neutrino mass generation with cosmological data
Koksbang, S. M.; Hannestad, S.
We study models in which neutrino masses are generated dynamically at cosmologically late times. Our study is purely phenomenological and parameterized in terms of three effective parameters characterizing the redshift of mass generation, the width of the transition region, and the present day neutrino mass. We also study the possibility that neut…