Cited by 38Galaxies: Formation, Evolution, PhenomenaAnomaly Detection Techniques and ApplicationsGamma-ray bursts and supernovae

Anomaly detection in Hyper Suprime-Cam galaxy images with generative adversarial networks

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Storey-Fisher, Kate, Huertas-Company, Marc, Ramachandra, Nesar, Lanusse, Francois, Leauthaud, Alexie, Luo, Yifei, Huang, Song, Prochaska, J Xavier·2021·Monthly Notices of the Royal Astronomical Society

Abstract

The problem of anomaly detection in astronomical surveys is becoming increasingly important as data sets grow in size. We present the results of an unsupervised anomaly detection method using a Wasserstein generative adversarial network (WGAN) on nearly one million optical galaxy images in the Hyper Suprime-Cam (HSC) survey. The WGAN learns to generate realistic HSC-like galaxies that follow the distribution of the data set; anomalous images are defined based on a poor reconstruction by the generator and outlying features learned by the discriminator. We find that the discriminator is more attuned to potentially interesting anomalies compared to the generator, and compared to a simpler autoencoder-based anomaly detection approach, so we use the discriminator-selected images to construct a high-anomaly sample of ∼13 000 objects. We propose a new approach to further characterize these anomalous images: we use a convolutional autoencoder to reduce the dimensionality of the residual differences between the real and WGAN-reconstructed images and perform UMAP clustering on these. We report detected anomalies of interest including galaxy mergers, tidal features, and extreme star-forming galaxies. A follow-up spectroscopic analysis of one of these anomalies is detailed in the Appendix; we find that it is an unusual system most likely to be a metal-poor dwarf galaxy with an extremely blue, higher-metallicity H ii region. We have released a catalogue with the WGAN anomaly scores; the code and catalogue are available at https://github.com/kstoreyf/anomalies-GAN-HSC; and our interactive visualization tool for exploring the clustered data is at https://weirdgalaxi.es.

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Crossref · 10.1093/mnras/stab2589

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Authors
Storey-Fisher, K., Huertas-Company, M., Ramachandra, N., Lanusse, F., Leauthaud, A., Luo, Y., Huang, S., & Prochaska, J. X.
Affiliations
  • New York University (US)
  • Instituto de Astrofísica de Canarias (IAC); Departamento de Astrofísica, Universidad de La Laguna (ULL) , E-38200 La Laguna, Spain
  • Argonne National Laboratory (US)
  • AIM, CEA, CNRS, Universite Paris-Saclay, Université de Paris , F-91191 Gif-sur-Yvette, France
  • Centre National de la Recherche Scientifique (FR)
  • University of California, Santa Cruz (US)
  • Kavli Institute for the Physics and Mathematics of the Universe (JP)
Corresponding author
Storey-Fisher, Kate
Venue
Monthly Notices of the Royal Astronomical Society
Published
2021-09-13
Volume
508
Issue
2
Pages
2946-2963
ISSN
  • 0035-8711 (ISSN-L)
  • 1365-2966
OpenAlex
W3158374188
Cited by
38
References
47
Citations by year
2026: 3 · 2025: 4 · 2024: 13 · 2023: 7 · 2022: 9 · 2021: 2
FWCI
4.16
Type
journal article
Language
en
Open access
Locations
  • Monthly Notices of the Royal Astronomical Society (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • HAL (submittedVersion, other-oa)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
  • arXiv (Cornell University)
Funders
  • University of California
  • Kavli Foundation
  • National Science Foundation (1714610)
  • U.S. Department of Energy
Topics
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Galaxies: Formation, Evolution, Phenomena
  • Physical Sciences › Computer Science › Artificial Intelligence › Anomaly Detection Techniques and Applications
  • Physical Sciences › Physics and Astronomy › Astronomy and Astrophysics › Gamma-ray bursts and supernovae
Keywords
anomaly detection, galaxy images, Wasserstein GAN, Hyper Suprime-Cam, unsupervised anomaly detection, galaxy mergers, tidal features, star-forming galaxies, metal-poor dwarf galaxies, H II regions, convolutional autoencoder, UMAP clustering, astronomical surveys

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