发表机构
The Open University; University of Minnesota; California Institute of Technology（开放大学; 明尼苏达大学; 加州理工学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用Faster R-CNN在约21万个低红移星系中探测到约71万个恒星形成团块，通过测光拟合得到其物理性质，发现其质量函数符合剧烈盘不稳定性原位形成，且团块内迁促进核球形成。
AI 中文摘要
巨型恒星形成团块（GSFCs）是尺度为千秒差距（kpc）的增强恒星形成区域，其恒星质量在$10^6$至$10^{10}\\,M_\odot$之间，通常在高红移（$z \gtrsim 1$）星系中被观测到，但它们的形成机制及其在星系演化中的作用仍不清楚。我们应用了Faster R-CNN目标检测框架（FRCNN），从Hyper Suprime-Cam Subaru战略巡天（HSC-SSP）和CFHT大面积U波段深度巡天（CLAUDS）观测到的HSC-SSP Wide和Deep天区中，识别了一个质量完备的样本——约210,000个低红移星系（$z\lesssim0.32$）——中的恒星形成团块。我们呈现了约710,000个探测到的团块样本，并为每个团块测量了(u)grizy测光数据，通过将测光数据拟合到恒星种群模型，推导了其物理性质（恒星质量、年龄、尘埃消光和恒星形成率）。我们估计，年轻团块（年龄<100百万年）的团块恒星质量函数（cSMF）在约$10^{8}\\,M_\odot$的完备性极限以下遵循幂律，指数为$\alpha=1.98\pm0.02$，这与通过剧烈盘不稳定性（VDI）进行的原位形成机制一致。这些团块表现出升高的恒星形成率，并且其年龄和恒星质量随星系中心距离呈负梯度。这些梯度比宿主星系团块间区域测得的梯度更陡峭，并且对不同建模假设引入的不确定性具有稳健性。对于邻近星系，我们认为观测到的低红移团块很可能是高红移GSFCs的类似物，并且恒星形成团块的内向迁移直接促进了宿主星系中央核球形成。
英文摘要
Giant Star-forming Clumps (GSFCs) are kpc-scale regions of enhanced star-formation with stellar masses of $10^6$ to $10^{10}\,M_\odot$ that are commonly observed in high-redshift ($z \gtrsim 1$) galaxies but their formation and role in galaxy evolution remain unclear. We applied a Faster R-CNN object detection framework (FRCNN) to identify star-forming clumps in astrophysical imaging data from a mass-complete sample of $\sim$210,000 low-redshift galaxies ($z\lesssim0.32$), located in the HSC-SSP Wide and Deep fields observed by the Hyper Suprime-Cam Subaru Strategic Survey (HSC-SSP) and CFHT Large Area U-band Deep Survey (CLAUDS). We present a population of $\sim$710,000 detected clumps for which we measured the (u)grizy-photometry and derived the physical properties (stellar mass, age, dust extinction and star-formation rate) for each clump by fitting the photometric data to stellar population models. We estimate that the clump Stellar Mass Function (cSMF) for young clumps ($<100\,\mathrm{Myr}$) follows a power law with an exponent of $α=1.98\pm0.02$ down to a completeness limit of $\sim10^{8}\,M_\odot$ which is consistent with an in situ formation through violent disk instabilities (VDI). The clumps show elevated star-formation rates and negative gradients in their ages and stellar masses as a function of galactocentric distance. These gradients are steeper than those measured for the intra-clump regions of the host galaxies and are robust against uncertainties introduced by different modelling assumptions. For nearby galaxies we argue that the observed low-redshift clumps are likely analogues of high-redshift GSFCs and that the inward migration of star-forming clumps directly contributes to the central bulge formation of the host galaxy.
Comments32 pages, submitted to MNRAS
