Measuring the intracluster light fraction with machine learning

TL;DR

This paper introduces a machine learning model that automates the measurement of intracluster light fractions in galaxy clusters, enabling rapid analysis of large imaging datasets with minimal manual effort.

Contribution

We developed a fully supervised machine learning approach trained on artificial data and fine-tuned on real images to efficiently measure ICL fractions in large surveys.

Findings

Model processes up to 500 images in seconds on a GPU.

Fine-tuning on real data takes only 3 minutes.

The approach is adaptable to different surveys and measurement methods.

Abstract

The intracluster light (ICL) is an important tracer of a galaxy cluster's history and past interactions. However, only small samples have been studied to date due to its very low surface brightness and the heavy manual involvement required for the majority of measurement algorithms. Upcoming large imaging surveys such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time are expected to vastly expand available samples of deep cluster images. However, to process this increased amount of data, we need faster, fully automated methods to streamline the measurement process. This paper presents a machine learning model designed to automatically measure the ICL fraction in large samples of images, with no manual preprocessing required. We train the fully supervised model on a training dataset of 50,000 images with injected artificial ICL profiles. We then transfer its learning onto real data by fine-tuning with a sample of 101 real clusters with their ICL fraction measured manually using the surface brightness threshold method. With this process, the model is able to effectively learn the task and then adapt its learning to real cluster images. Our model can be directly applied to Hyper Suprime-Cam images, processing up to 500 images in a matter of seconds on a single GPU, or fine-tuned for other imaging surveys such as LSST, with the fine-tuning process taking just 3 minutes. The model could also be retrained to match other ICL measurement methods. Our model and the code for training it is made available on GitHub.