Abstract
Interpretation of data from faint dwarf galaxies is made challenging by observations limited to only the brightest stars. We present a major improvement to tackle this challenge by undertaking zoomed cosmological simulations that resolve the evolution of all individual stars more massive than 0.5 M⊙, thereby explicitly tracking all observable stars for the Hubble time. For the first time, we predict observable color-magnitude diagrams and the spatial distribution of ≈100,000 stars within four faint (M⋆ ≈ 105 M⊙) dwarf galaxies directly from their cosmological initial conditions. In all cases, simulations predict complex light profiles with multiple components, implying that typical observational measures of structural parameters can make the total V-band magnitudes appear up to 0.5 mag dimmer compared to estimates from simulations. Furthermore, when only small (⪅100) numbers of stars are observable, shot noise from realizations of the color-magnitude diagram introduces uncertainties comparable to the population scatter in, e.g., the total magnitude, half-light radius, and mean iron abundance measurements. Estimating these uncertainties with fully self-consistent mass growth, star formation, and chemical enrichment histories paves the way for more robust interpretation of dwarf galaxy data.
| Original language | English |
|---|---|
| Article number | 129 |
| Journal | Astrophysical Journal |
| Volume | 978 |
| Issue number | 2 |
| Early online date | 3 Jan 2025 |
| DOIs | |
| Publication status | Published - 10 Jan 2025 |
Acknowledgements
We thank the anonymous referee for comments and suggestions that greatly improved the quality of this work. We acknowledge Mordecai-Mark Mac Low for helpful comments improving the quality of this manuscript.Funding
E.A. acknowledges support from NASA ATP grant 80NSSC24K0935 and NSF grant AST23-07950. M.R. is supported by the Beecroft Fellowship funded by Adrian Beecroft. O.A. acknowledges support from the Knut and Alice Wallenberg Foundation, the Swedish Research Council (grant 2019-04659), and the Swedish National Space Agency (SNSA Dnr 2023-00164). A.P. was supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 818085 GMGalaxies). J.I.R. would like to acknowledge support from STFC grants ST/Y002865/1 and ST/Y002857/1 This work used the DiRAC Data Intensive service (DIaL2/DIaL) at the University of Leicester, managed by the University of Leicester Research Computing Service on behalf of the STFC DiRAC HPC Facility (www.dirac.ac.uk). The DiRAC service at Leicester was funded by BEIS, UKRI, and STFC capital funding and STFC operations grants. DiRAC is part of the UKRI Digital Research Infrastructure. We thank the Astrophysics Data Service funded by NASA under Cooperative Agreement 80NSSC21M00561 and the arXiv preprint repository for providing services that were used extensively in this work.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science