Mathieu Remazeilles, PhD

As a cosmologist, I study the origin, content, and evolution of the Universe. My research focuses on extracting and interpreting new cosmological observables from submillimetre and radio observations of the sky, primarily out of the cosmic microwave background (CMB), the relic light from the Big Bang that encodes the Universe’s initial conditions.

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A key challenge in cosmology is the component separation problem: disentangling cosmological signals in the early Universe from astrophysical foreground emissions in the nearby Universe, which obscure much of the cosmological information. To address this, I develop new component separation techniques, for example the Constrained ILC and GNILC methods which are now widely used by the community to analyze CMB and radio data, including those from ESA’s Planck mission.

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Launched by ESA in 2009, Planck was designed to measure temperature and polarization anisotropies in the CMB. As a Planck scientist, I proposed novel methods to extract and characterise faint or complex emissions beyond the CMB itself, including the Sunyaev-Zeldovich (SZ) effects, the cosmic infrared background (CIB) anisotropies, and Galactic foregrounds. I have produced several public maps in Astronomy, including the Planck NILC all-sky map of thermal SZ effect, the Planck GNILC maps of CIB and Galactic dust, or the Reprocessed Haslam 408-MHz map.​

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My current research interests include: (i) Searching for primordial CMB B-mode polarization as a signature of gravitational waves from cosmic inflation; (ii) Mapping thermal, kinetic, and relativistic SZ effects to study how baryonic and dark matter distributions shape the large-scale structure of the Universe; (iii) Detecting subtle CMB spectral distortions caused by early physical processes before the epoch of recombination; (iv) Tracing baryonic acoustic oscillations through the 21-cm hydrogen line emission. I am involved in several major CMB and radio experiments and international collaborations, including LiteBIRD, QUIJOTE, Simons Observatory (SO), PICO, BISOU, and BINGO, that aim to shed light on these elusive components of the Universe.​​​