Main Research Fields

I’m an ESA Research Fellow at the Space Telescope Science Institute (STScI) in Baltimore and a member of the SH0ES team. My research focuses on astronomical distance measurements with Cepheid variables and the determination of the Hubble Constant (H₀). The current tension between the local measurement of H₀ based on Cepheid and Type Ia supernova distances and its value inferred from the Λ-CDM model calibrated with CMB data in the early universe has reached a 5σ significance. This intriguing discrepancy, which has been recently confirmed with JWST observations of Cepheids, provides growing hints of new physics beyond Λ-CDM.  

I work on improving the primary calibration of Cepheid distances in the Local Group, in particular with parallaxes from the Gaia satellite in the Milky Way and with space-based photometry from the Hubble Space Telescope (HST). I am also interested in reducing systematic uncertainties in Cepheid distances, for example the metallicity dependence of Cepheids brightness. Finally, I also started investigating different standard candles such as the Tip of the Red Giant Branch (TRGB) and Carbon stars (the J-region Asymptotic Giant Branch, JAGB), which can substitute Cepheids in the distance ladder.