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Julien Lesgourgues

Cette personne a quitté l’EPFL

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Publications associées (71)

Page 1 sur 4

Constraints on primordial non-Gaussianity

Julien Lesgourgues

The Planck nominal mission cosmic microwave background (CMB) maps yield unprecedented constraints on primordial non-Gaussianity (NG). Using three optimal bispectrum estimators, separable template-fitting (KSW), binned, and modal, we obtain consistent value ...

Edp Sciences S A2014

Planck 2013 results. VII. HFI time response and beams

Julien Lesgourgues

This paper characterizes the effective beams, the effective beam window functions and the associated errors for the Planck High Frequency Instrument (HFI) detectors. The effective beam is the angular response including the effect of the optics, detectors, ...

Edp Sciences S A2014

Planck 2013 results. XX. Cosmology from Sunyaev-Zeldovich cluster counts

Julien Lesgourgues

We present constraints on cosmological parameters using number counts as a function of redshift for a sub-sample of 189 galaxy clusters from the Planck SZ (PSZ) catalogue. The PSZ is selected through the signature of the Sunyaev-Zeldovich (SZ) effect, and ...

Edp Sciences S A2014

Planck 2013 results. IX. HFI spectral response

Xin Chen, Julien Lesgourgues

The Planck High Frequency Instrument (HFI) spectral response was determined through a series of ground based tests conducted with the HFI focal plane in a cryogenic environment prior to launch. The main goal of the spectral transmission tests was to measur ...

Edp Sciences S A2014

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

Julien Lesgourgues, Jason Douglas McEwen

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

Structure formation with massive neutrinos: going beyond linear theory

Julien Lesgourgues, Diego Blas Temino

We compute non-linear corrections to the matter power spectrum taking the time-and scale-dependent free-streaming length of neutrinos into account. We adopt a hybrid scheme that matches the full Boltzmann hierarchy to an effective two-fluid description at ...

Iop Publishing Ltd2014

Single-field inflation constraints from CMB and SDSS data

Julien Lesgourgues

We present constraints on canonical single-field inflation derived from WMAP five year, ACBAR, QUAD, BICEP data combined with the halo power spectrum from SDSS LRG7. Models with a non-scale-invariant spectrum and a red tilt n(S) < 1 are now preferred over ...

2010

Planck 2013 results. XVI. Cosmological parameters

Xin Chen, Julien Lesgourgues

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

Planck 2013 results. XXX. Cosmic infrared background measurements and implications for star formation

Xin Chen, Julien Lesgourgues

We present new measurements of cosmic infrared background (CIB) anisotropies using Planck. Combining HFI data with IRAS, the angular auto-and cross-frequency power spectrum is measured from 143 to 3000 GHz, and the auto-bispectrum from 217 to 545 GHz. The ...

Edp Sciences S A2014

Planck 2013 results. V. LFI calibration

Xin Chen, Julien Lesgourgues

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

Model independent constraints on mass-varying neutrino scenarios

Julien Lesgourgues

Models of dark energy in which neutrinos interact with the scalar field supposed to be responsible for the acceleration of the Universe usually imply a variation of the neutrino masses on cosmological time scales. In this work we propose a parametrization ...

American Physical Society2009

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

Dark goo: bulk viscosity as an alternative to dark energy

Julien Lesgourgues

We present a simple (microscopic) model in which bulk viscosity plays a role in explaining the present acceleration of the universe. The effect of bulk viscosity on the Friedmann equations is to turn the pressure into an "effective" pressure containing the ...

2011

CMB power spectra and likelihood

Julien Lesgourgues

This paper presents the Planck 2013 likelihood, a complete statistical description of the two-point correlation function of the CMB temperature fluctuations that accounts for all known relevant uncertainties, both instrumental and astrophysical in nature. ...

Edp Sciences S A2014

Cosmology intertwined: A review of the particle physics, astrophysics, and cosmology associated with the cosmological tensions and anomalies

Frédéric Courbin, Julien Lesgourgues, Mikhail Ivanov, Richard Irving Anderson

The standard Lambda Cold Dark Matter (Lambda CDM) cosmological model provides a good description of a wide range of astrophysical and cosmological data. However, there are a few big open questions that make the standard model look like an approximation to ...

ELSEVIER2022

Planck 2013 results. XXVI. Background geometry and topology of the Universe

Julien Lesgourgues, Jason Douglas McEwen

The new cosmic microwave background (CMB) temperature maps from Planck provide the highest-quality full-sky view of the surface of last scattering available to date. This allows us to detect possible departures from the standard model of a globally homogen ...

Edp Sciences S A2014

Planck 2013 results. XVIII. The gravitational lensing-infrared background correlation

Julien Lesgourgues

The multi-frequency capability of the Planck satellite provides information both on the integrated history of star formation (via the cosmic infrared background, or CIB) and on the distribution of dark matter (via the lensing effect on the cosmic microwave ...

Edp Sciences S A2014

CMB photons shedding light on dark matter

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

Planck 2013 results. XXI. Power spectrum and high-order statistics of the Planck all-sky Compton parameter map

Julien Lesgourgues

We have constructed the first all-sky map of the thermal Sunyaev-Zeldovich (tSZ) effect by applying specifically tailored component separation algorithms to the 100 to 857 GHz frequency channel maps from the Planck survey. This map shows an obvious galaxy ...

Edp Sciences S A2014

A White Paper on keV sterile neutrino Dark Matter

Antoine Pierre Emmanuel Alexis Merle, Julien Lesgourgues, Alexey Boyarsky, Oleg Ruchayskiy, Igor Tkachev, Marco Drewes, Laurent Gastaldo

We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved - cosmology, astrophysics, nuclear, and particle physics - in each case viewed from both theoretical and experimental/o ...

Iop Publishing Ltd2017