Total and dark mass from observations of galaxy centers with Machine Learning

TL;DR

This paper introduces a machine learning method using Random Forests to accurately estimate total and dark matter content in galaxy centers from simple observational data, validated against simulations and real low-redshift galaxy datasets.

Contribution

The paper presents a novel machine learning approach, Mela, for predicting galaxy dark matter content using minimal observational features, outperforming traditional dynamical methods.

Findings

Accurately predicts dark matter masses within 0.30 dex for diverse galaxy types.

Reproduces dynamical masses with minimal bias and outliers across datasets.

Effective regardless of kinematic data quality or analysis method.

Abstract

The galaxy total mass inside the effective radius encode important information on the dark matter and galaxy evolution model. Total "central" masses can be inferred via galaxy dynamics or with gravitational lensing, but these methods have limitations. We propose a novel approach, based on Random Forest, to make predictions on the total and dark matter content of galaxies using simple observables from imaging and spectroscopic surveys. We use catalogs of multi-band photometry, sizes, stellar mass, kinematic "measurements" (features) and dark matter (targets) of simulated galaxies, from Illustris-TNG100 hydrodynamical simulation, to train a Mass Estimate machine Learning Algorithm (Mela). We separate the simulated sample in passive early-type galaxies (ETGs), both "normal" and "dwarf", and active late-type galaxies (LTGs) and show that the mass estimator can accurately predict the galaxy dark masses inside the effective radius in all samples. We finally test the mass estimator against the central mass estimates of a series of low redshift (z$\leq$0.1) datasets, including SPIDER, MaNGA/DynPop and SAMI dwarf galaxies, derived with standard dynamical methods based on Jeans equations. Dynamical masses are reproduced within 0.30 dex ($\sim2\sigma$), with a limited fraction of outliers and almost no bias. This is independent of the sophistication of the kinematical data collected (fiber vs. 3D spectroscopy) and the dynamical analysis adopted (radial vs. axisymmetric Jeans equations, virial theorem). This makes Mela a powerful alternative to predict the mass of galaxies of massive stage-IV surveys' datasets.