Warped Disk Galaxies: Statistical Properties from DESI Legacy Imaging Surveys DR8

Abstract Warped structures are often observed in disk galaxies, yet their physical origin is still under investigation. We present a systematic study of warped edge-on disk galaxies based on imaging data from the DESI Legacy Imaging Surveys DR8, with the expectation that this large sample size, enabled by wide-area surveys, will offer new perspectives on the formation of disk warps. Using a deep learning approach, we trained an EfficientNet-B3 convolutional neural network to classify the morphology of edge-on-disk galaxies into warped and nonwarped categories. Our model was trained on a curated and visually verified set of labeled galaxy images and applied to a large dataset of 595,651 edge-on disk galaxies selected from the Galaxy Zoo DESI catalog. Our results provide the largest warp catalog to date, consisting of 23,996 warped edge-on disk galaxies, and reveal statistical trends between warp occurrence and galaxy properties. Compared to their nonwarped counterparts, these warped disk galaxies tend to have bluer colors, lower stellar masses, higher gas fractions and star formation rates, smaller Sérsic indices, and larger disk sizes. In addition, warped disk galaxies show higher projected number densities of neighboring galaxies than their nonwarped counterparts, particularly within R proj ≲ 50 kpc, where the local number density is roughly twice as high.