Spectral evolution of white dwarfs with J-PLUS

Carlos López San Juan (CEFCA)

Abstract: White dwarfs can be classified in two main classes: H- and He-dominated atmospheres. The fraction of each type changes as white dwarfs cool down, referred as spectral evolution, reflecting the impact of different physical mechanism in their evolution. I present our results regarding the spectral evolution of 5926 white dwarfs with Gaia DR3 parallaxes and J-PLUS DR2 (12 optical bands, 5 broad + 7 narrow) information. The properties of the white dwarfs (effective temperature, surface gravity, mass, and composition) were estimated using J-PLUS photometry and Gaia parallax as prior. Then, the spectral evolution was estimated at 30 000 ＞ Teff ＞ 5000 K with a hierarchical Bayesian model. We find a constant fraction of He-dominated white dwarfs at high temperatures, with an increase at Teff ＞ 20 000 K. The mass distribution of these two types are different: H-dominated have a main peak at M = 0.6 Msun with an excess at M = 0.8 Msun, but such excess is not present for He-dominated white dwarfs. Finally, the forecast for J-PAS (56 optical narrow bands of 14.5 nm) regarding the spectral evolution topic is presented.

Bio: Carlos López San Juan get his PhD in 2009 at Instituto de Astrofísica de Canarias (IAC) studying galaxy mergers at cosmoslogical distances. After a first postdoc at the Laboratoire d'Astrophysique de Marseille (LAM), he moved to the Centro de Estudios de Física del Cosmos de Aragón (CEFCA) in 2012. Since then, he developed statistical tools for multifilter surveys as J-PLUS and J-PAS to study galaxies and Milky Way stars. He is the head of the Research Area in CEFCA since 2020 and Deputy Director since last 2023.