Search Publications
The Knotted Sky I: Planck constraints on the primordial power spectrum
Aslanyan, Grigor; Easther, Richard; Price, Layne C. +1 more
Using the temperature data from Planck we search for departures from a power-law primordial power spectrum, employing Bayesian model-selection and posterior probabilities. We parametrize the spectrum with n knots located at arbitrary values of logk, with both linear and cubic splines. This formulation recovers both slow modulations and sharp trans…
Testing inflation and curvaton scenarios with CMB distortions
Clesse, Sébastien; Garbrecht, Björn; Zhu, Yi
Prior to recombination, Silk damping causes the dissipation of energy from acoustic waves into the monopole of the Cosmic Microwave Background (CMB), resulting in spectral distortions. These can be used to probe the primordial scalar power spectrum on smaller scales than it is possible with CMB anisotropies. An enhancement of power on these scales…
What is the distance to the CMB?
Clarkson, Chris; Maartens, Roy; Durrer, Ruth +1 more
The success of precision cosmology depends not only on accurate observations, but also on the theoretical model --- which must be understood to at least the same level of precision. Subtle relativistic effects can lead to biased measurements if they are neglected. One such effect gives a systematic shift in the distance-redshift relation away from…
Strong Planck constraints on braneworld and non-commutative inflation
Calcagni, Gianluca; Kuroyanagi, Sachiko; Ohashi, Junko +1 more
We place observational likelihood constraints on braneworld and non-commutative inflation for a number of inflaton potentials, using Planck, WMAP polarization and BAO data. Both braneworld and non-commutative scenarios of the kind considered here are limited by the most recent data even more severely than standard general-relativity models. At mor…
Precision growth index using the clustering of cosmic structures and growth data
Basilakos, Spyros; Plionis, Manolis; Pouri, Athina
We use the clustering properties of Luminous Red Galaxies (LRGs) and the growth rate data provided by the various galaxy surveys in order to constrain the growth index γ) of the linear matter fluctuations. We perform a standard χ2-minimization procedure between theoretical expectations and data, followed by a joint likelihood analysis a…
Constraining the dynamical dark energy parameters: Planck-2013 vs WMAP9
Novosyadlyj, B.; Sergijenko, O.; Durrer, R. +1 more
We determine the best-fit values and confidence limits for dynamical dark energy parameters together with other cosmological parameters on the basis of different datasets which include WMAP9 or Planck-2013 results on CMB anisotropy, BAO distance ratios from recent galaxy surveys, magnitude-redshift relations for distant SNe Ia from SNLS3 and Union…
The Atacama Cosmology Telescope: cross correlation with Planck maps
Hasselfield, Matthew; Bond, J. Richard; Devlin, Mark J. +26 more
We present the temperature power spectrum of the Cosmic Microwave Background obtained by cross-correlating maps from the Atacama Cosmology Telescope (ACT) at 148 and 218 GHz with maps from the Planck satellite at 143 and 217 GHz, in two overlapping regions covering 592 square degrees. We find excellent agreement between the two datasets at both fr…
Reconstructing the local potential of inflation with BICEP2 data
Ma, Yin-Zhe; Wang, Yi
We locally reconstruct the inflationary potential by using the current constraints on r and ns from BICEP2 data. Assuming small and negligible αs, the inflationary potential is approximately linear in Δϕ~ Mpl range but becomes non-linear in Δϕ~ 10 Mpl range. However if we vary the value of αs …
Power-law cosmology, SN Ia, and BAO
Halenka, Vitali; Dolgov, Aleksander; Tkachev, Igor
We revise observational constraints on the class of models of modified gravity which at low redshifts lead to a power-law cosmology. To this end we use available public data on Supernova Ia and on baryon acoustic oscillations. We show that the expansion regime a(t) ~ tβ with β close to 3/2 in a spatially flat universe is a good fit to t…
Parameters of cosmological models and recent astronomical observations
Sharov, G. S.; Vorontsova, E. G.
For different gravitational models we consider limitations on their parameters coming from recent observational data for type Ia supernovae, baryon acoustic oscillations, and from 34 data points for the Hubble parameter H(z) depending on redshift. We calculate parameters of 3 models describing accelerated expansion of the universe: the ΛCDM model,…