Using machine learning to study the kinematics of cold gas in galaxies

TL;DR

This paper demonstrates how machine learning, specifically convolutional autoencoders, can classify and analyze the kinematic behavior of cold gas in galaxies using simulated and real interferometric data, enabling rapid, reliable insights for upcoming large-scale surveys.

Contribution

It introduces a machine learning framework that embeds kinematic features into a 3D space to classify galaxy gas dynamics and predict parameters efficiently, suitable for next-generation radio telescopes.

Findings

Achieved 85% recall on simulated data for classifying galaxy kinematics.

Predicted galaxy position angles with 17-23 degree uncertainty.

Model performs with 95% heuristic accuracy on observational data.

Abstract

Next generation interferometers, such as the Square Kilometre Array, are set to obtain vast quantities of information about the kinematics of cold gas in galaxies. Given the volume of data produced by such facilities astronomers will need fast, reliable, tools to informatively filter and classify incoming data in real time. In this paper, we use machine learning techniques with a hydrodynamical simulation training set to predict the kinematic behaviour of cold gas in galaxies and test these models on both simulated and real interferometric data. Using the power of a convolutional autoencoder we embed kinematic features, unattainable by the human eye or standard tools, into a three-dimensional space and discriminate between disturbed and regularly rotating cold gas structures. Our simple binary classifier predicts the circularity of noiseless, simulated, galaxies with a recall of $85\%$ and performs as expected on observational CO and HI velocity maps, with a heuristic accuracy of $95\%$. The model output exhibits predictable behaviour when varying the level of noise added to the input data and we are able to explain the roles of all dimensions of our mapped space. Our models also allow fast predictions of input galaxies' position angles with a $1\sigma$ uncertainty range of $\pm17^{\circ}$ to $\pm23^{\circ}$ (for galaxies with inclinations of $82.5^{\circ}$ to $32.5^{\circ}$, respectively), which may be useful for initial parameterisation in kinematic modelling samplers. Machine learning models, such as the one outlined in this paper, may be adapted for SKA science usage in the near future.