Current Lagrange Postdoctoral Fellows

#Josquin Errard

I did my studies at the Ecole Normale Supérieure of Paris (France) and did my PhD under the supervision of Radek Stompor at Laboratoire Astroparticule & Cosmologie (Paris, France). I defended my thesis, "A hunt for CMB B-modes in the systematic contaminants jungle", in September 2012.

I worked at the Computational Cosmology Center (LBNL) in Berkeley (US) as a postdoctoral fellow in observational cosmology, where I focused on the analysis and scientific exploitation of the data coming from the new generation CMB B-modes experiment called POLARBEAR. With my collaborators, we did the first direct measurement of CMB B-modes produced by gravitational lensing. This important result gave a strong support to our current understanding of cosmic history, opening new observational windows onto the physics of the early and late Universe.

I joined ILP in September 2015 with the project of constraining the dark sector (dark matter, dark energy) and cosmic inflation by combining different and complementary observational tools, in particular CMB polarization (using data from new and future telescopes such as Polarbear-II, Simons Array, Stage-IV, LiteBIRD) and optical lensing with HSC and LSST.

We recently published several articles with the POLARBEAR collaboration, among which:
Gravitational Lensing of Cosmic Microwave Background Polarization
The Polarbear collaboration
Phys. Rev. Lett. 113, 021301 (2014)
Evidence for B-Mode Polarization of the CMB from Cross-correlating Gravitational Lensing with the Cosmic Infrared Background
The Polarbear collaboration
Phys. Rev. Lett. 112, 131302 (2014)
A Measurement of the Cosmic Microwave Background B-Mode Polarization Power Spectrum at Sub-degree Scales with Polarbear
The Polarbear Collaboration
The Astrophysical Journal, Volume 794, 171 (2014)

In addition, I worked on designing and optimizing future CMB telescopes. My collaborators and I focused on different systematic effects, in particular the astrophysical foregrounds, the gravitational lensing and the atmospheric contamination for ground-based projects:
A Guide to Designing Future Ground-based Cosmic Microwave Background Experiments
Wu K., Errard J. et al.
The Astrophysical Journal, Volume 788, Issue 2, article id. 138, 19 pp. (2014)
Modeling Atmospheric Emission for CMB Ground-based Observations
Errard J. with the Polarbear collaboration
The Astrophysical Journal, Volume 809, Issue 1, article id. 63, 19 pp. (2015)
Robust forecasts on fundamental physics from the foreground-obscured, gravitationally-lensed CMB polarization
Errard J., Feeney S. M., Peiris H. V. and Jaffe A. H. (2015)

Contact: josquin.errard[at]lpnhe[dot]in2p3[dot]fr