Validating full-spectrum fitting with a synthetic integral-field spectroscopic observation of the Milky Way

TL;DR

This paper introduces GalCraft, a new tool for generating synthetic integral-field spectroscopic data of the Milky Way, and uses it to validate full-spectrum fitting methods like pPXF in recovering stellar kinematics and populations.

Contribution

The study presents GalCraft, a novel code that creates mock IFS data of the MW, enabling validation of spectral fitting techniques and analysis of chemodynamical features.

Findings

Differences in kinematics and stellar populations between thin and thick disks can be distinguished.

Age distribution is overestimated in certain ranges due to template degeneracy.

Systematic offsets in kinematic recovery are caused by spectral resolution limitations.

Abstract

Ongoing deep IFS observations of disk galaxies provide opportunities for comparison with the Milky Way (MW) to understand galaxy evolution. However, such comparisons are marred by many challenges such as selection effects, differences in observations and methodology, and proper validation of full-spectrum fitting methods. In this study, we present a novel code GalCraft to address these challenges by generating mock IFS data cubes of the MW using simple stellar population models and a mock MW stellar catalog derived from E-Galaxia. We use the widely adopted full-spectrum fitting code pPXF to investigate the ability to recover kinematics and stellar populations for an edge-on mock MW IFS observation. We confirm that differences in kinematics, mean age, [M/H], and [$\alpha$/Fe] between thin and thick disks can be distinguished. However, the age distribution is overestimated in the ranges between 2 - 4 and 12 - 14 Gyr compared to the expected values. This is likely due to the age spacing and degeneracy of SSP templates. We find systematic offsets in the recovered kinematics due to insufficient spectral resolution and the variation of line-of-sight velocity distribution with age and [M/H]. With future higher resolution and multi-[$\alpha$/Fe] SSP templates, GalCraft will be useful to validate key signatures such as [$\alpha$/Fe]-[M/H] distribution at different $R$ and $|z|$ and potentially infer radial migration and kinematic heating efficiency to study detailed chemodynamical evolution of MW-like galaxies.