用深度学习自动识别射电星系形态,区分喷流结构类型。
RGC: a radio AGN classifier based on deep learning. I. A semi-supervised multiclass model for VLA images
- 结合自监督预训练与等变卷积网络,利用有标签和无标签数据提升分类精度。
- 在四类射电星系分类中达到0.79的宏平均F1分数,优于传统模型。
- 可视化注意力聚焦真实喷流结构,适合天文环境探测与演化研究。
弯曲型射电活动星系核(RAGN)——宽角尾(WAT)与窄角尾(NAT)——可揭示星系群和星系团中的致密环境,但尚无多类别分类器能同时将它们与直型费纳罗夫-赖里类型(sFRI、sFRII)区分开,且基于人工标注与未标注数据。本文发布FIRST-2060数据集,包含2060个经多层级视觉检验标记的RAGN样本(四类:sFRI、sFRII、WAT、NAT),来源于三个公开目录。同时推出半监督模型RGC 1.0,利用20,000个未标注源进行训练。模型融合自监督框架BYOL与$E(2)$-等变可导向卷积神经网络(E2CNN)编码器,在未标注数据上预训练,再在标注数据上微调。六种模型通过五折交叉验证、Grad-CAM注意力分析及受控类别不平衡实验评估。ConvNeXT($M_1$)与RGC($M_2$)在宏平均F1上分别达$0.80/pm0.02$与$0.79/pm0.02$,差异在标准差内。仅$M_2$的Grad-CAM热力图能一致追踪射电星系的真实形态结构(瓣、喷流、弯折),而非默认为紧凑斑块或弥散模式。本研究提出的四分类方案支持实现分辨WAT/NAT的星表,可用于环境探针及弥漫簇射电辐射的前体分类。$M_1$与$M_2$互补优势——跨类型与同类型判别能力——表明集成方法可能成为大规模形态星表的实用框架。
原文摘要 · Abstract (English)
Bent radio active galactic nuclei (RAGNs) -- wide-angle tails (WATs) and narrow-angle tails (NATs) -- trace dense environments in galaxy groups and clusters, yet no multiclass classifier simultaneously separates them from straight Fanaroff--Riley types (sFRI, sFRII) using visually inspected labels and unlabelled data. We release FIRST-2060, a four-class labelled dataset of 2060 RAGNs (sFRI, sFRII, WAT, NAT) constructed from three publicly available catalogues through multi-tier visual inspection, together with the semi-supervised RGC 1.0 model that leverages 20,000 unlabelled sources. We benchmark RGC against five supervised baselines. FIRST-2060 is provided in two preprocessing variants: $\mathbf{R}_{L1}$, which retains spurious sources, and $\mathbf{R}_{L2}$, from which they are removed. The RGC model integrates the self-supervised framework BYOL (Bootstrap Your Own Latent) with an $E(2)$-equivariant steerable CNN (E2CNN) encoder, pre-trained on the unlabelled data and fine-tuned on the labelled sets. All six models are evaluated with 5-fold cross-validation, Grad-CAM attention analysis, and controlled class-imbalance experiments. ConvNeXT ($M_1$) and RGC ($M_2$) form a top tier at macro-$F_1$ $0.80\pm0.02$ and $0.79\pm0.02$ respectively, a difference within one standard deviation. $M_2$ is the only model whose Grad-CAM contours consistently trace the morphological structure of RAGNs -- lobes, jets, and bends -- rather than defaulting to compact blobs or diffuse patterns. The four-class scheme introduced here enables WAT/NAT-resolved catalogues that can serve as environment probes and progenitor classifications for diffuse cluster radio emission. The complementary strengths of $M_1$ and $M_2$ -- in cross-type and within-type discrimination respectively -- suggest that an ensemble approach may offer a practical framework for survey-scale morphological catalogues.
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