标题： 对延伸的边缘朝向低表面亮度星系的更深入观察 显示英文标题

标题： A closer look at the extended edge-on low-surface brightness galaxies

摘要： 为了理解低表面亮度（LSB）星系延伸盘的起源，我们详细研究了4个具有大盘结构且边缘朝向我们的系统。其中两个是最近由我们团队识别的边缘朝向的大质量LSB星系（gLSBGs）。这些系统的边缘朝向提高了它们的表面亮度，提供了光谱学上表征恒星种群的机会，并为边缘朝向的gLSBGs提供了首次此类测量。我们使用1.4米Milanković望远镜对其中一个星系进行了深度成像，并将其与存档的Subaru Hyper Suprime-Cam和DESI Legacy巡天数据相结合，这些数据适用于其他三个系统，并测量了盘的结构参数。我们使用俄罗斯6米望远镜和10米Keck II望远镜获取了深度长缝光谱，并估算了高表面亮度和低表面亮度区域的恒星种群特性以及气体相金属度分布。气体金属度梯度在0到-0.03 dex每指数盘尺度长度范围内是平缓的或平坦的，这与较小盘星系的梯度-尺度长度关系的外推一致。我们在LSB盘中的恒星速度弥散估计以及盘的相对厚度表明了动力学过热。我们的观测支持合并是大质量LSB星系形成情景中的关键阶段。 显示英文摘要

摘要： To understand the origin of extended disks of low-surface brightness (LSB) galaxies, we studied in detail 4 such systems with large disks seen edge-on. Two of them are edge-on giant LSB galaxies (gLSBGs) recently identified by our team. The edge-on orientation of these systems boosts their surface brightnesses that provided an opportunity to characterize stellar populations spectroscopically and yielded the first such measurements for edge-on gLSBGs. We collected deep images of one galaxy using the 1.4-m Milankovi\'c Telescope which we combined with the archival Subaru Hyper Suprime-Cam and DESI Legacy Surveys data available for the three other systems, and measured the structural parameters of the disks. We acquired deep long-slit spectra with the Russian 6-meter telescope and the 10-m Keck II telescope and estimated stellar population properties in the high- and low-surface brightness regions as well as the gas-phase metallicity distribution. The gas metallicity gradients are shallow to flat in the range between 0 and -0.03 dex per exponential disk scale length, which is consistent with the extrapolation of the gradient -- scale length relation for smaller disk galaxies. Our estimates of stellar velocity dispersion in the LSB disks as well as the relative thickness of the disks indicate the dynamical overheating. Our observations favor mergers as the essential stage in the formation scenario for massive LSB galaxies.