AR 14557 (Archival Research)

Sun Jul 14 19:08:22 GMT 2024

Principal Investigator: Charlie Conroy
PI Institution: Harvard University
Investigators (xml)

Title: Measuring the Star Formation History of the Local Universe
Cycle: 24

The main body of nearly every galaxy within 20 Mpc is in the 'semi-resolved' regime, in which source confusion/crowding dominates, and yet the brightest stars (e.g., massive stars and evolved giants) are rare enough to induce stochastic fluctuations in the light distribution. In this regime we define the concept of pixel color magnitude diagrams (pixel CMDs), which allow one to reconstruct non-parametric star formation histories (SFHs) from semi-resolved imaging data. Here we propose to analyze pixel CMDs for 20 galaxies within 20 Mpc in order to measure spatially resolved SFHs for a representative sample (by mass) of galaxies within the local universe. These measurements will enable a first estimate of the total SFH within the local volume, which can then be compared to the cosmic SFH from lookback studies and to detailed galaxy formation models. The resulting SFHs will also be used to investigate variations across morphological types, radial variations within galaxies, and differences (or not) between ellipticals, classical, and pseudobulges. As part of this program we will deliver a suite of well-tested tools for analyzing pixel CMDs from HST data.