Papers › AstroCLIP: A Cross-Modal Foundation Model for Galaxies

AstroCLIP: A Cross-Modal Foundation Model for Galaxies

4 Oct 2023arXiv:2310.03024archive 2025-07-28

Liam Parker, Francois Lanusse, Siavash Golkar, Leopoldo Sarra, Miles Cranmer, Alberto Bietti, Michael Eickenberg, Geraud Krawezik, Michael McCabe, Ruben Ohana, Mariel Pettee, Bruno Regaldo-Saint Blancard, Tiberiu Tesileanu, Kyunghyun Cho, Shirley Ho

We present AstroCLIP, a single, versatile model that can embed both galaxy images and spectra into a shared, physically meaningful latent space. These embeddings can then be used - without any model fine-tuning - for a variety of downstream tasks including (1) accurate in-modality and cross-modality semantic similarity search, (2) photometric redshift estimation, (3) galaxy property estimation from both images and spectra, and (4) morphology classification. Our approach to implementing AstroCLIP consists of two parts. First, we embed galaxy images and spectra separately by pretraining separate transformer-based image and spectrum encoders in self-supervised settings. We then align the encoders using a contrastive loss. We apply our method to spectra from the Dark Energy Spectroscopic Instrument and images from its corresponding Legacy Imaging Survey. Overall, we find remarkable performance on all downstream tasks, even relative to supervised baselines. For example, for a task like photometric redshift prediction, we find similar performance to a specifically-trained ResNet18, and for additional tasks like physical property estimation (stellar mass, age, metallicity, and sSFR), we beat this supervised baseline by 19\% in terms of R². We also compare our results to a state-of-the-art self-supervised single-modal model for galaxy images, and find that our approach outperforms this benchmark by roughly a factor of two on photometric redshift estimation and physical property prediction in terms of R², while remaining roughly in-line in terms of morphology classification. Ultimately, our approach represents the first cross-modal self-supervised model for galaxies, and the first self-supervised transformer-based architectures for galaxy images and spectra.

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AstroClipModel PolymathicAI/AstroCLIP/astroclip/models/astroclip.py official repository ran MIT (permissive) · 788c03b4f5ddff93 · report
CLIPLoss PolymathicAI/AstroCLIP/astroclip/models/astroclip.py official repository ran MIT (permissive) · 36c97be9f076b733 · report

Tasks

Contrastive LearningMorphology classificationPhotometric Redshift EstimationProperty PredictionSemantic SimilaritySemantic Textual Similaritymodel

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ALIGNContrastive Learning

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