Search Publications
Revisiting constraints on the (pseudo)conformal universe with Planck data
Rubtsov, G. I.; Ramazanov, S. R.
We revisit constraints on the (pseudo)conformal universe from the nonobservation of statistical anisotropy in the Planck data. The quadratic maximal likelihood estimator is applied to the Planck temperature maps at frequencies 143 and 217 GHz as well as their cross-correlation. The strongest constraint is obtained in the scenario of the (pseudo)co…
Cosmic microwave background anisotropies in the timescape cosmology
Wiltshire, David L.; Nazer, M. Ahsan
We analyze the spectrum of cosmic microwave background (CMB) anisotropies in the timescape cosmology: a potentially viable alternative to homogeneous isotropic cosmologies without dark energy. We exploit the fact that the timescape cosmology is extremely close to the standard cosmology at early epochs to adapt existing numerical codes to produce C…
Constraints on the basic parameters of dark matter using the Planck data
Yang, Yupeng
Dark matter (DM) annihilation or decay can affect the anisotropy of the cosmic microwave background (CMB). Therefore, the CMB data can be used to constrain the properties of a dark matter particle. In this work, we use the new CMB data obtained by the Planck satellite to investigate the limits on the basic parameters of a dark matter particle. The…
Tensors, BICEP2 results, prior dependence, and dust
Liddle, Andrew R.; Parkinson, David; Cortês, Marina
We investigate the prior dependence on the inferred spectrum of primordial tensor perturbations, in light of recent results from BICEP2 and taking into account a possible dust contribution to polarized anisotropies. We highlight an optimized parametrization of the tensor power spectrum, and adoption of a logarithmic prior on its amplitude AT<…
Inflation that runs naturally: Gravitational waves and suppression of power at large and small scales
Kaplinghat, Manoj; Minor, Quinn E.
We point out three correlated predictions of the axion monodromy inflation model: the large amplitude of gravitational waves, the suppression of power on horizon scales and on scales relevant for the formation of dwarf galaxies. While these predictions are likely generic to models with oscillations in the inflaton potential, the axion monodromy mo…
Transients in finite inflation
Scacco, Andrew; Albrecht, Andreas
We test a model of inflation with a fast-rolling kinetic-dominated initial condition against data from Planck using Markov chain Monte Carlo parameter estimation. We test both an m2ϕ2 potential and the R +R2 gravity model and perform a full numerical calculation of both the scalar and tensor primordial power spectr…
Role of higher-dimensional evolving wormholes in the formation of a big rip singularity
Setare, M. R.; Sepehri, A.
We study the four-dimensional Universe on the M2-M5 BIon in the thermal background. The BIon is a configuration in a flat space of a D-brane and a parallel anti-D-brane connected by a wormhole. When the branes and antibranes are well separated and the brane's spike is far from the antibrane's spike, the wormhole cannot be formed. However, when two…
Possible evidence for Planck-scale resonant particle production during inflation from the CMB power spectrum
Mathews, G. J.; Gangopadhyay, M. R.; Ichiki, K. +1 more
The power spectrum of the cosmic microwave background from both the Planck and WMAP data exhibits a slight dip for multipoles in the range of l =10 - 30 . We show that such a dip could be the result of the resonant creation of massive particles that couple to the inflaton field. For our best-fit models, the epoch of resonant particle creation reen…
Testing the tensor-vector-scalar theory with the latest cosmological observations
Wang, Bin; Zhang, Pengjie; Xu, Xiao-dong
The tensor-vector-scalar (TeVeS) model is considered a viable theory of gravity. It produces the Milgrom's modified Newtonian dynamics in the nonrelativistic weak field limit and is free from ghosts. This model has been tested against various cosmological observations. Here, we investigate whether new observations such as the galaxy velocity power…
Signatures of the very early Universe: Inflation, spatial curvature, and large scale anomalies
Aslanyan, Grigor; Easther, Richard
A short inflationary phase may not erase all traces of the primordial Universe. Associated observables include both spatial curvature and "anomalies" in the microwave background or large-scale structure. The present curvature ΩK ,0 reflects the initial curvature, ΩK ,start , and the angular size of anomalies depends on k…