CASCO: Cosmological and AStrophysical parameters from Cosmological simulations and Observations IV. Testing warm dark matter cosmologies with galaxy scaling relations: A joint simulation-observation study using DREAMS simulations

TL;DR

This study uses combined large-volume and high-resolution simulations with observational data to test warm dark matter models, focusing on galaxy scaling relations and their sensitivity to cosmological and dark matter parameters.

Contribution

It introduces a joint simulation-observation approach that effectively constrains cosmological parameters and explores WDM effects, especially at low stellar masses, advancing dark matter research.

Findings

Cosmological parameters are accurately recovered from simulations.

WDM particle mass remains unconstrained, but low-mass galaxy trends are sensitive to WDM.

Galaxy stellar mass function shows WDM dependence below 10^8 solar masses.

Abstract

Small-scale discrepancies in the standard Lambda cold dark matter paradigm have motivated the exploration of alternative dark matter (DM) models, such as warm dark matter (WDM). We investigate the constraining power of galaxy scaling relations on cosmological, astrophysical, and WDM parameters through a joint analysis of hydrodynamic simulations and observational data. Our study is based on the DREAMS project and combines large-volume uniform-box simulations with high-resolution Milky Way zoom-in runs in a $\Lambda$WDM cosmology. To ensure consistency between the different simulation sets, we apply calibrations to account for resolution effects, allowing us to exploit the complementary strengths of the two suites. We compare simulated relations, including stellar size, DM mass and fraction within the stellar half-mass radius, and the total-to-stellar mass ratio, with two complementary galaxy samples: the SPARC catalog of nearby spirals and the LVDB catalog of dwarf galaxies in the Local Volume. Using a bootstrap-based fitting procedure, we show that key cosmological parameters ($\Omega_m$, $\sigma_8$) and supernova feedback strength can be recovered with good accuracy, particularly from the uniform-box simulations. While the WDM particle mass remains unconstrained, the zoom-in simulations reveal subtle WDM-induced trends at low stellar masses in both the DM mass and total-to-stellar mass ratio. We also find that the galaxy stellar mass function exhibits a measurable dependence on the WDM particle mass below log10(M_*/Msun) <~ 8, which appears separable from the impact of feedback, suggesting it as a promising complementary probe. Our results highlight the importance of combining multi-resolution simulations with diverse observational datasets to jointly constrain baryonic processes and DM properties.