Semi-Supervised Learning for Lensed Quasar Detection

Fuente: arXiv
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Main Authors: Sweeney, David, Krone-Martins, Alberto, Stern, Daniel, Tuthill, Peter, Scalzo, Richard, Djorgovski, George, Ducourant, Christine, Mahabal, Ashish, Teixeira, Ramachrisna, Graham, Matthew
Format: Preprint
Published: 2025
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author Sweeney, David
Krone-Martins, Alberto
Stern, Daniel
Tuthill, Peter
Scalzo, Richard
Djorgovski, George
Ducourant, Christine
Mahabal, Ashish
Teixeira, Ramachrisna
Graham, Matthew
author_facet Sweeney, David
Krone-Martins, Alberto
Stern, Daniel
Tuthill, Peter
Scalzo, Richard
Djorgovski, George
Ducourant, Christine
Mahabal, Ashish
Teixeira, Ramachrisna
Graham, Matthew
contents Lensed quasars are key to many areas of study in astronomy, offering a unique probe into the intermediate and far universe. However, finding lensed quasars has proved difficult despite significant efforts from large collaborations. These challenges have limited catalogues of confirmed lensed quasars to the hundreds, despite theoretical predictions that they should be many times more numerous. We train machine learning classifiers to discover lensed quasar candidates. By using semi-supervised learning techniques we leverage the large number of potential candidates as unlabelled training data alongside the small number of known objects, greatly improving model performance. We present our two most successful models: (1) a variational autoencoder trained on millions of quasars to reduce the dimensionality of images for input to a dense neural network classifier that can make accurate predictions and (2) a convolutional neural network trained on a mix of labelled and unlabelled data via virtual adversarial training. These models are both capable of producing high-quality candidates, as evidenced by our discovery of GRALJ140833.73+042229.98. The success of our classifier, which uses only multi-band images, is particularly exciting as it can be combined with existing classifiers, which use other data than images, to improve the classifications of both models and discover more lensed quasars.
format Preprint
id arxiv_https___arxiv_org_abs_2504_00054
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Semi-Supervised Learning for Lensed Quasar Detection
Sweeney, David
Krone-Martins, Alberto
Stern, Daniel
Tuthill, Peter
Scalzo, Richard
Djorgovski, George
Ducourant, Christine
Mahabal, Ashish
Teixeira, Ramachrisna
Graham, Matthew
Instrumentation and Methods for Astrophysics
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
Lensed quasars are key to many areas of study in astronomy, offering a unique probe into the intermediate and far universe. However, finding lensed quasars has proved difficult despite significant efforts from large collaborations. These challenges have limited catalogues of confirmed lensed quasars to the hundreds, despite theoretical predictions that they should be many times more numerous. We train machine learning classifiers to discover lensed quasar candidates. By using semi-supervised learning techniques we leverage the large number of potential candidates as unlabelled training data alongside the small number of known objects, greatly improving model performance. We present our two most successful models: (1) a variational autoencoder trained on millions of quasars to reduce the dimensionality of images for input to a dense neural network classifier that can make accurate predictions and (2) a convolutional neural network trained on a mix of labelled and unlabelled data via virtual adversarial training. These models are both capable of producing high-quality candidates, as evidenced by our discovery of GRALJ140833.73+042229.98. The success of our classifier, which uses only multi-band images, is particularly exciting as it can be combined with existing classifiers, which use other data than images, to improve the classifications of both models and discover more lensed quasars.
title Semi-Supervised Learning for Lensed Quasar Detection
topic Instrumentation and Methods for Astrophysics
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2504.00054