发表机构
Hamburger Sternwarte, Universität Hamburg（汉堡天文台，汉堡大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对射电巡天数据增长，提出用潜在扩散模型合成逼真射电图像切片，并通过顺序采样与上下文向量实现任意大小巡天图生成，可精确控制源位置和亮度。
AI 中文摘要
射电巡天提供了指数级增长的观测数据，这要求开发新的数据归约和分析方法。为此，对观测数据进行逼真的模拟可为测试和开发新方法提供受控环境。扩散模型擅长合成逼真的图像数据，但受限于尺寸约束和高计算需求。我们实现了一个潜在扩散模型（LDM）来合成逼真的射电巡天图像切片。此外，我们开发了一种利用LDM采样任意大小射电巡天图像的技术。这是通过多个顺序步骤进行采样实现的，其中通过上下文向量和图像修复提供一致性。我们使用LOFAR望远镜从LOFAR两米巡天第三次数据发布中获得的观测数据训练了模型。我们实现了一个由向量量化变分自编码器和作用于所得潜在表示的扩散模型组成的LDM。我们通过从公开源星表中提取参数并将其编码为向量格式作为上下文传递给LDM，添加了源位置、亮度和大小信息。我们训练了图像修复模型以促进连续顺序采样。我们能够生成512像素边长（对应约5.7角分）的逼真切片，并精确控制源位置和亮度。对源延展的控制以较低精度实现。任意大小图像的采样成为可能，显示出逼真的结果，各个样本无缝组合，仅受偶尔的采样伪影限制。
英文摘要
Radio surveys provide exponentially increasing amounts of observational data, which requires the development of novel data reduction and analysis methods. To this end, realistic simulations of observational data provide controlled environments for testing and developing new methods. Diffusion models excel at synthesizing realistic image data, but are limited by size constraints and high computational demands. We implemented a latent diffusion model (LDM) to synthesize realistic radio survey map cutouts. Further, we developed a technique for sampling radio survey maps of arbitrary size with the LDM. This is done by sampling in multiple sequential steps, whereby consistency is provided through context vectors and image inpainting. We trained our model on observations from the LOFAR telescope obtained from the third data release of the LOFAR Two-Metre Sky Survey. We implemented a LDM composed of a vector-quantized variational autoencoder and a diffusion model operating on the resulting latent representations. We added information on source locations, brightness and sizes by extracting parameters from the public source catalog and encoding them into a vector format passed as context to the LDM. We trained the model for image inpainting to facilitate continuous sequential sampling. We were able to generate realistic cutouts of 512 pixel side length, corresponding to ~5.7 arcmin, with precise control over source locations and brightness. Control over source extension was achieved at lower precision. Sampling of arbitrary-sized maps was made possible, showing realistic results with seamless combination of individual samples and limited only by occasional sampling artifacts.
