200,000 Candidate Very Metal-poor Stars in Gaia DR3 XP Spectra

Understand

Very metal-poor stars ($\rm[Fe/H] < -2$) in the Milky Way are fossil records of early chemical evolution and the assembly and structure of the Galaxy.

• However, they are rare and hard to find.
• Gaia DR3 has provided over 200 million low-resolution ($R \approx 50$) XP spectra, which provides an opportunity to greatly increase the number of candidate metal-poor stars.
• In this work, we utilise the \texttt{XGBoost} classification algorithm to identify $\sim$200,000 very metal-poor star candidates.