论文标题
超湿星系作为极端的星形环境I：高素质UDGS中的映射星形形成
Ultra-Diffuse Galaxies as Extreme Star-forming Environments I: Mapping Star Formation in HI-Rich UDGs
论文作者
论文摘要
超湿星系既是星系进化的极端产物，也是测试我们对恒星形成的理解的极端环境。在这项工作中，我们将22个Hi选择的UDG和35个低质量星系的空间分辨的星形形成活性与120 MPC之内的NASA Sloan Atlas（NSA）进行了对比。我们采用一种新的关节拟合方法来计算星形的形成速率和出色的质量表面密度图，以利用高空间分辨率的光学成像数据的高空化学成像数据（HSC-SSP）和Galex的UV覆盖范围以及从估计的HI Radial Profiles，以及从具有Spatatibal Sespatibaled Spatibaled Spatibaled Hi Mamaps的Galaxies估计的HI Radial Propiles。我们发现，UDG的恒星形成效率低，其原子气的函数下降到500 pc的尺度。我们还发现，当将UDG样品的出色质量加权大小视为其HI质量的函数时，它们的恒星大小与固定HI Mass的NSA矮人相当。这是UDG正常形成恒星的图片中的自然结果，但效率低。我们将我们的结果与当代星系形成模型的预测进行了比较，并特别发现我们的观察结果在模型中很难再现，在这种模型中，由于剧烈的恒星形成反馈，如果需要爆发恒星形成，则需要$ z = 0 $。
Ultra-Diffuse Galaxies are both extreme products of galaxy evolution and extreme environments in which to test our understanding of star formation. In this work, we contrast the spatially resolved star formation activity of a sample of 22 HI-selected UDGs and 35 low-mass galaxies from the NASA Sloan Atlas (NSA) within 120 Mpc. We employ a new joint SED fitting method to compute star formation rate and stellar mass surface density maps that leverage the high spatial resolution optical imaging data of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) and the UV coverage of GALEX, along with HI radial profiles estimated from a subset of galaxies that have spatially resolved HI maps. We find that the UDGs have low star formation efficiencies as a function of their atomic gas down to scales of 500 pc. We additionally find that the stellar mass-weighted sizes of our UDG sample are unremarkable when considered as a function of their HI mass -- their stellar sizes are comparable to the NSA dwarfs at fixed HI mass. This is a natural result in the picture where UDGs are forming stars normally, but at low efficiencies. We compare our results to predictions from contemporary models of galaxy formation, and find in particular that our observations are difficult to reproduce in models where UDGs undergo stellar expansion due to vigorous star formation feedback should bursty star formation be required down to $z=0$.
