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Julien Lesgourgues

Cette personne n’est plus à l’EPFL

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Publications associées (71)

Probing nuclear rates with Planck and BICEP2

Julien Lesgourgues

Big-bang nucleosynthesis (BBN) relates key cosmological parameters to the primordial abundance of light elements. In this paper, we point out that the recent observations of cosmic microwave background anisotropies by the Planck satellite and by the BICEP2 ...

American Physical Society2014

High Frequency Instrument data processing

Julien Lesgourgues, Fabio Finelli, Xin Chen

We describe the processing of the 531 billion raw data samples from the High Frequency Instrument (HFI), which we performed to produce six temperature maps from the first 473 days of Planck-HFI survey data. These maps provide an accurate rendition of the s ...

Edp Sciences S A2014

Using the CMB angular power spectrum to study Dark Matter-photon interactions

Julien Lesgourgues

In this paper, we explore the impact of Dark Matter-photon interactions on the CMB angular power spectrum. Using the one-year data release of the Planck satellite, we derive an upper bound on the Dark Matter-photon elastic scattering cross section of sigma ...

Iop Publishing Ltd2014

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

Planck 2013 results. XXII. Constraints on inflation

Julien Lesgourgues, Fabio Finelli, Jan Hamann, Jean-Luc Starck

We analyse the implications of the Planck data for cosmic inflation. The Planck nominal mission temperature anisotropy measurements, combined with the WMAP large-angle polarization, constrain the scalar spectral index to be n(s) = 0.9603 +/- 0:0073, ruling ...

EDP Sciences2014

Planck 2013 results. XXIII. Isotropy and statistics of the CMB

Julien Lesgourgues, Fabio Finelli, Jason Douglas McEwen, Ji Hyun Kim

The two fundamental assumptions of the standard cosmological model - that the initial fluctuations are statistically isotropic and Gaussian - are rigorously tested using maps of the cosmic microwave background (CMB) anisotropy from the Planck satellite. Th ...

Edp Sciences S A2014

Planck 2013 results. I. Overview of products and scientific results

Slobodan Ilic, Julien Lesgourgues, Fabio Finelli, Jason Douglas McEwen, Jan Hamann, Ji Hyun Kim, Xin Chen

The European Space Agency's Planck satellite, dedicated to studying the early Universe and its subsequent evolution, was launched 14 May 2009 and has been scanning the microwave and submillimetre sky continuously since 12 August 2009. In March 2013, ESA an ...

Edp Sciences S A2014

Planck 2013 results. XVII. Gravitational lensing by large-scale structure

Julien Lesgourgues, Fabio Finelli

On the arcminute angular scales probed by Planck, the cosmic microwave background (CMB) anisotropies are gently perturbed by gravitational lensing. Here we present a detailed study of this effect, detecting lensing independently in the 100, 143, and 217 GH ...

Edp Sciences S A2014

Planck 2013 results. IV. Low Frequency Instrument beams and window functions

Julien Lesgourgues, Fabio Finelli

This paper presents the characterization of the in-flight beams, the beam window functions, and the associated uncertainties for the Planck Low Frequency Instrument (LFI). Knowledge of the beam profiles is necessary for determining the transfer function to ...

Edp Sciences S A2014

Planck 2013 results. V. LFI calibration

Julien Lesgourgues, Fabio Finelli, Xin Chen

We discuss the methods employed to photometrically calibrate the data acquired by the Low Frequency Instrument on Planck. Our calibration is based on a combination of the orbital dipole plus the solar dipole, caused respectively by the motion of the Planck ...

Edp Sciences S A2014

The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths

Julien Lesgourgues

We present the Planck Sky Model (PSM), a parametric model for generating all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model the cos ...

Edp Sciences S A2013

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

Neutrino masses and cosmological parameters from a Euclid-like survey: Markov Chain Monte Carlo forecasts including theoretical errors

Julien Lesgourgues, Benjamin Audren

We present forecasts for the accuracy of determining the parameters of a minimal cosmological model and the total neutrino mass based on combined mock data for a future Euclid-like galaxy survey and Planck. We consider two different galaxy surveys: a spect ...

Iop Publishing Ltd2013

The CLASSgal code for relativistic cosmological large scale structure

Ruth Durrer, Julien Lesgourgues

We present accurate and efficient computations of large scale structure observables, obtained with a modified version of the c l ass code which is made publicly available. This code includes all relativistic corrections and computes both the power spectrum ...

Iop Publishing Ltd2013

Conservative constraints on early cosmology with MONTE PYTHON

Julien Lesgourgues, Benjamin Audren

Models for the latest stages of the cosmological evolution rely on a less solid theoretical and observational ground than the description of earlier stages like BBN and recombination. As suggested in a previous work by Vonlanthen et al., it is possible to ...

Iop Publishing Ltd2013

Cosmological constraints on Lorentz violating dark energy

Sergey Sibiryakov, Julien Lesgourgues, 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

CMB photons shedding light on dark matter

Gaëlle Giesen, Julien Lesgourgues, Benjamin Audren

The annihilation or decay of Dark Matter (DM) particles could affect the thermal history of the universe and leave an observable signature in Cosmic Microwave Background (CMB) anisotropies. We update constraints on the annihilation rate of DM particles in ...

Iop Publishing Ltd2012

Neutrino Mass from Cosmology

Julien Lesgourgues

Neutrinos can play an important role in the evolution of the universe, modifying some of the cosmological observables. In this contribution we summarize the main aspects of cosmological relic neutrinos, and we describe how the precision of present cosmolog ...

Hindawi Publishing Corporation2012

Cosmological lepton asymmetry with a nonzero mixing angle theta(13)

Julien Lesgourgues

While the baryon asymmetry of the Universe is nowadays well measured by cosmological observations, the bounds on the lepton asymmetry in the form of neutrinos are still significantly weaker. We place limits on the relic neutrino asymmetries using some of t ...

American Physical Society2012

Non-linear matter power spectrum from Time Renormalisation Group: efficient computation and comparison with one-loop

Julien Lesgourgues, Benjamin Audren

We address the issue of computing the non-linear matter power spectrum on mildly non-linear scales with efficient semi-analytic methods. We implemented M. Pietroni's Time Renormalization Group (TRG) method and its Dynamical 1-Loop (D1L) limit in a numerica ...

2011

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