Cmb temperature map

Clara Vergès

Observational cosmologist, specialised in instrument modeling, systematic studies and data analysis for Cosmic Microwave Background (CMB) polarisation experiments.

I am currently a Harvard Postdoctoral Fellow at the Center for Astrophysics in Cambridge (USA), within the CMB group. Before that, I was a PhD student at APC in Paris, where I obtained my PhD in September 2020. I am a member of the BICEP/Keck and CMB-S4 collaborations

Selfie with a telescope

Selfie with the POLARBEAR-2a telescope during its commissioning in Chile, in November 2019

Research interests

My research work focuses on studying the signal of the CMB to look for a specific polarisation pattern: the cosmological B-modes. The detection of this signal would be a smoking gun for inflation theories, allowing us to better understand the very beginning of the Universe.

I focus on calibration and systematics in the context of multi-component data anaylsis. I develop advanced data analysis techniques to precisely estimate the impact of instrumental systematics on our science results, and how to mitigate their impact in various ways. I also actively participate in design, integration and calibration of current and future receivers.



Understanding instrumental systematics require high precision calibration data, as these measurements are an essential step to ensure that instrumental effects are properly taken into account in the analysis. I work first-hand on calibration campaign for CMB telescopes, to make sure we have all necessary measurements to understand the performance of our instruments.

Instrumental systematics

I work on estimating the impact of various instrumental effects on science results, in particular on cosmological parameters of interest in the search for inflation. I develop frameworks to analyse calibration data and tie them to cosmological analysis. This work also informs calibration campaigns, so that we know the precision of the measurement we need to properly constraint instrumental effects.


Component separation

One of the main challenges in our quest for B-modes is to be able to separate the CMB signal from Galactic contaminations. This step, known as component separation, requires accurate models of both the instrument and Galactic emission. I develop component separation methods that take into account the interplay between instrumental characteristics and foreground complexity.

Cosmic birefringence

Cosmic birefringence is an elusive manifestation of parity violation in the electromagnetic interaction. It would manifest as a rotation of CMB polarisation as the signal travels through our Universe. The amplitude of this effect is very low, and degenerate with instrumental polarisation. Constraining it is therefore a instrumental and data analysis challenge. With James Cornelison, we have been leading the effort in the BK collaboration to extract birefringence constraints from our CMB data... stay tuned!


I love sharing my passion for astrophysics outside the lab! I regularly engage in outreach activities, most recently with Skype a Scientist, and I often participate in events organised by the CMB-S4 Education & Public Outreach program. I am also Astrophysics & Physics expert for Fête le Savoir. In the past, I had the chance to be part of Universciel and SpaceUp France, and organise many wonderful events with them! Whether the focus is space, astrophysics or general science, I always enjoy planning, crafting and hosting events, packed with conferences, workshops, hands-on activities, for kids and adults alike!

Conference Astrojeunes Summer camp

CV & Publications

  • Full CV
  • Publication list
  • PhD dissertation