Predicting dust temperature from molecular line data using machine learning

TL;DR

This study demonstrates that machine learning can accurately predict dust temperatures in molecular clouds using molecular line data alone, reducing the need for multi-band continuum observations and revealing links to PDR regions.

Contribution

It shows that a small training sample with representative temperature distribution suffices for accurate predictions and highlights the importance of the $^{12}$CO / $^{13}$CO ratio as a key feature.

Findings

Approximately 5% of pixels are enough for training.

Training data should cover the full temperature range.

The $^{12}$CO / $^{13}$CO ratio is a crucial predictor.

Abstract

We conducted experiments with machine learning techniques to construct dust temperature maps from the CO isotopologue molecular line data in the Orion A molecular cloud. In the classical astrophysical methodology, multi-band continuum data are required to derive the dust temperature. The present study aims to investigate the capability and limitations of machine learning techniques to derive dust temperatures in regions without multi-band dust continuum data. We investigated how the number of pixels used for training influences prediction accuracy, and how the dust temperatures sampled in the training area influence prediction accuracy. We found that $\sim$5\% of the total number of pixels in the observational region is sufficient for training to obtain accurate predictions. Furthermore, a dust temperature sample within the training area should cover the whole temperature range and have a similar sample distribution to that of the entire observing region for an accurate prediction. The $^{12}$CO / $^{13}$CO ratio is often found to be the most important feature in predicting the dust temperature. As the $^{12}$CO / $^{13}$CO ratio is a tracer of PDR, the machine learning technique could connect the dust temperatures to the PDRs. We also found that the condition of thermal gas-dust coupling is not required for accurate prediction of the dust temperature from the molecular line data, and that machine learning is capable of capturing information more than classical astrophysical concepts.