Dr. Louise Breuval

Since January 2022, I’m a postdoctoral researcher
at Johns Hopkins University in Baltimore, MD, USA,
and a member of the SH0ES team.

I completed my PhD in Astrophysics in October 2021
at Paris Observatory (LESIA) and PSL university,
as a member of the Araucaria Project.

I study the distance scale of the Universe with Cepheid stars.

Recent releases

An Improved Calibration of the Wavelength Dependence of Metallicity on the Cepheid Leavitt Law

Breuval et al., ApJ 939, 89 (2022). We describe the contribution of various systematic effects in the determination of the metallicity effect (γ). We find no evidence of γ changing over the wavelength range 0.5-4.5 μm, indicating that the main influence of metallicity on Cepheids is in their luminosity rather than color.

The influence of metallicity on the Leavitt law from geometrical distances of Milky Way and Magellanic Clouds Cepheids

Breuval et al., ApJ 913, 38 (2021). Adopting Cepheid parallaxes from Gaia EDR3 and the distances of LMC and SMC Cepheids obtained from eclipsing binaries, we derive that metal-rich Cepheids are intrinsically brighter than their metal-poor counterparts.

The Milky Way Cepheid Leavitt law based on Gaia DR2 parallaxes of companion stars and host open cluster populations

Breuval et al. (2020), A&A 643, A115. As a proxy for the parallaxes of 36 Galactic Cepheids, we adopt either the GDR2 parallaxes of their spatially resolved companions or the GDR2 parallax of their host open cluster. This novel approach allows us to bypass the systematics on the GDR2 Cepheids parallaxes that is induced by saturation and variability.