Effect of line-of-sight depth on recovery of intermediate-age and old SFH components

Characterize how the inclusion of line-of-sight depth influences the accuracy and reliability of recovering star formation histories for intermediate-age and old stellar populations in colour–magnitude diagram fitting with THESTORM using the two-step procedure based on red clump luminosity functions, especially under decreasing age resolution conditions.

Background

The paper introduces a two-step star formation history (SFH) recovery method that first derives an initial SFH without line-of-sight depth and then estimates the depth using the red clump (RC) luminosity function to inject a Gaussian-distributed magnitude dispersion into synthetic CMDs for a final SFH fit.

Mock tests demonstrate clear improvements in young-age and metallicity recovery when the line-of-sight depth is considered, particularly for larger depths (up to ~21 kpc). However, the authors note that age resolution decreases at intermediate and old ages, making it difficult to assess how line-of-sight depth affects the recovery of these populations.