Search Publications
The small scale power asymmetry in the cosmic microwave background
Flender, Samuel; Hotchkiss, Shaun
We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales. We find an anomalously high asymmetry in the multipole range l = 601-2048, with a naive statistical significance of 6.5σ. However, we show that this extreme anomaly is simply a coincidence of three other effects, relativistic power modulati…
Reconstruction of broad features in the primordial spectrum and inflaton potential from Planck
Hazra, Dhiraj Kumar; Smoot, George F.; Shafieloo, Arman
With the recently published Cosmic Microwave Background data from Planck we address the optimized binning of the primordial power spectrum. As an important modification to the usual binning of the primordial spectrum, along with the spectral amplitude of the bins, we allow the position of the bins also to vary. This technique enables us to address…
Mixed inflaton and spectator field models after Planck
Takahashi, Tomo; Enqvist, Kari
We investigate the possibility that the primordial perturbation has two sources: the inflaton and a spectator field, which is not dynamically important during inflation but which after inflation can contribute to the curvature perturbation. We derive the constraints on the model by using recent Planck results on the spectral index, tensor-to-scala…
(Lack of) Cosmological evidence for dark radiation after Planck
Peiris, Hiranya V.; Verde, Licia; Feeney, Stephen M. +1 more
We use Bayesian model comparison to determine whether extensions to Standard-Model neutrino physics — primarily additional effective numbers of neutrinos and/or massive neutrinos — are merited by the latest cosmological data. Given the significant advances in cosmic microwave background (CMB) observations represented by the Planck data, we examine…
Measuring the thermal Sunyaev-Zel'dovich effect through the cross correlation of Planck and WMAP maps with ROSAT galaxy cluster catalogs
Battaglia, Nicholas; Bond, J. Richard; Spergel, David N. +3 more
We measure a significant correlation between the thermal Sunyaev-Zel'dovich effect in the Planck and WMAP maps and an X-ray cluster map based on ROSAT. We use the 100, 143 and 343 GHz Planck maps and the WMAP 94 GHz map to obtain this cluster cross spectrum. We check our measurements for contamination from dusty galaxies using the cross correlatio…
Testing the dipole modulation model in CMBR
Jain, Pankaj; Rath, Pranati K.
The hemispherical power asymmetry, observed in the CMBR data, has generally been interpreted in terms of the dipole modulation model for the temperature fluctuations. Here we point out that this model leads to several predictions, which can be directly tested in the current data. We suggest tests of the hemispherical power asymmetry both in real a…
Warming up for Planck
Rosa, João G.; Bartrum, Sam; Berera, Arjun
The recent Planck results and future releases on the horizon present a key opportunity to address a fundamental question in inflationary cosmology of whether primordial density perturbations have a quantum or thermal origin, i.e. whether particle production may have significant effects during inflation. Warm inflation provides a natural arena to a…
Single-field inflation à la generalized Chaplygin gas
del Campo, Sergio
In the simplest scenario for inflation, i.e. in the single-field inflation, it is presented an inflaton field with properties equivalent to a generalized Chaplygin gas. Their study is performed using the Hamilton-Jacobi approach to cosmology. The main results are contrasted with the measurements recently released by the Planck data, combined with …
Large-scale anomalies of the CMB in the curvaton scenario
Liu, Hao; Naselsky, Pavel; Frejsel, Anne Mette
We extend the curvaton scenario presented by Erickcek et al. [1,2], to explain how the even-odd multipole asymmetry of the Cosmic Microwave Background (CMB) (also called parity asymmetry, [3,4]) and power anisotropies can be generated by the curvaton field, which acts as an extra component to the spectrum of adiabatic perturbations in the inflatio…
Orbifold line topology and the cosmic microwave background
Rathaus, Ben; Ben-David, Assaf; Itzhaki, Nissan
We extend our study of a universe with a non-classical stringy topology, and consider an orbifold line topology, Bbb R × Bbb R2/Bbb Zp. This topology has a fixed line and identifies each point in space with p-1 other points. An observable imprint of an orbifold line on the CMB is the appearance of up to (p-1)/2 pairs of match…