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Friedmann equations

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Fast and accurate CMB computations in non-flat FLRW universes

Julien Lesgourgues

We present a new method for calculating CMB anisotropies in a non-flat Friedmann universe, relying on a very stable algorithm for the calculation of hyperspherical Bessel functions, that can be pushed to arbitrary precision levels. We also introduce a new ...

Iop Publishing Ltd2014

Higgs-Dilaton cosmology: Universality versus criticality

Javier Rubio

The Higgs-Dilaton model is able to produce an early inflationary expansion followed by a dark energy dominated era responsible for the late time acceleration of the Universe. At tree level, the model predicts a small tensor-to-scalar ratio (0.0021

Amer Physical Soc2014

Planck 2013 results. XVI. Cosmological parameters

Xin Chen, Julien Lesgourgues, Fabio Finelli, Jan Hamann

This paper presents the first cosmological results based on Planck measurements of the cosmic microwave background (CMB) temperature and lensing-potential power spectra. We find that the Planck spectra at high multipoles (l greater than or similar to 40) a ...

Edp Sciences S A2014

Light-cone anisotropy in the 21 cm signal from the epoch of reionization

Yves Revaz

Using a suite of detailed numerical simulations, we estimate the level of anisotropy generated by the time evolution along the light cone of the 21 cm signal from the epoch of reionization. Our simulations include the physics necessary to model the signal ...

Wiley-Blackwell2014

Kinetic initial conditions for inflation

Sylvain Bréchet

We consider the classical evolution of the inflaton field and the Hubble parameter in homogeneous and isotropic single-field inflation models. Under an extremely broad assumption, we show that the Universe generically emerges from an initial singularity in ...

American Physical Society2014

Optimal polarisation equations in FLRW universes

Julien Lesgourgues

This paper presents the linearised Boltzmann equation for photons for scalar, vector and tensor perturbations in flat, open and closed FLRW cosmologies. We show that E- and B-mode polarisation for all types can be computed using only a single hierarchy. Th ...

Iop Publishing Ltd2013

Higgs-dilaton cosmology: An effective field theory approach

Georgios Karananas, Javier Rubio

The Higgs-dilaton cosmological model is able to describe simultaneously an inflationary expansion in the early Universe and a dark energy dominated stage responsible for the present day acceleration. It also leads to a nontrivial relation between the spect ...

Amer Physical Soc2013

Cosmological constraints on Lorentz violating dark energy

Julien Lesgourgues, Sergey Sibiryakov, Diego Blas Temino, Benjamin Audren

The role of Lorentz invariance as a fundamental symmetry of nature has been lately reconsidered in different approaches to quantum gravity. It is thus natural to study whether other puzzles of physics may be solved within these proposals. This may be the c ...

Iop Publishing Ltd2013

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XIV. Time delay of the doubly lensed quasar SDSS J1001+5027

Frédéric Courbin, Georges Meylan, Malte Tewes

This paper presents optical R-band light curves and the time delay of the doubly imaged gravitationally lensed quasar SDSS J1001+5027 at a redshift of 1.838. We have observed this target for more than six years, between March 2005 and July 2011, using the ...

Edp Sciences S A2013

Least-restrictive robust periodic model predictive control applied to room temperature regulation

Colin Neil Jones

State-feedback model predictive control (MPC) of constrained discrete-time periodic affine systems is considered. The periodic systems’ states and inputs are subject to periodically time-dependent, hard, polyhedral constraints. Disturbances are additive, b ...

Elsevier2013