标题： DIISC-V：附近星系中恒星形成区域的H$α$至远紫外恒星形成率比值变化 显示英文标题

标题： DIISC-V: Variations in H$α$-to-FUV Star Formation Rate Ratios Across Star-forming Regions in Nearby Galaxies

摘要： 我们展示了远紫外（FUV）和H$\alpha$星形成率（SFR）、SFR$_{UV}$和SFR$_{H\alpha}$在11个星系中的变化，这些星系位于亚千秒差距尺度上，这是解密星系间介质、恒星与星系周围介质相互作用（DIISC）调查的一部分。 利用存档的GALEX FUV图像和使用梵蒂冈先进技术望远镜获得的H$\alpha$+[NII]窄带图像，我们分别检测到1335个（FUV选定）和1474个（H$\alpha$选定）近期高质量恒星形成的区域。 我们发现，对于FUV选源的区域，H$\alpha$至FUV的SFR比值往往较低，对于SFR$_{H\alpha}$来说，通常会低估SFR约2到3倍，当SFR$<$大于10$^{-4}$M$_{\odot}$年$^{-1}$时尤其如此。 相比之下，对于H$\alpha$选源的区域，SFR通常被观测为一致。 这种差异源于这两个指标之间的形态学差异。 星系外部区域的FUV形态扩展以及仅由FUV覆盖的更大面积，加上FUV块状结构与致密HII区之间的重叠程度减小（$R/R_{25}$），表明初始质量函数的随机取样效应在外围区域可能更加显著。 我们观测到的H$\alpha$-到-FUV的SFR比值也与随机恒星形成模型的预测一致。 然而，使用包含弥散FUV发射的大孔径会导致SFR$_{H\alpha}$和SFR$_{UV}$之间相差1 dex。 这表明星系中观测到的低H$\alpha$-到-FUV的SFR比值很可能是由于弥散FUV发射造成的，它可以贡献$\sim$60-90%的总FUV通量。 显示英文摘要

摘要： We present the variations in far-ultraviolet (FUV) and H$\alpha$ star formation rates (SFR), SFR$_{UV}$ and SFR$_{H\alpha}$, respectively, at sub-kpc scales in 11 galaxies as part of the Deciphering the Interplay between the Interstellar Medium, Stars, and the Circumgalactic medium (DIISC) survey. Using archival GALEX FUV imagery and H$\alpha$+[NII] narrowband images obtained with the Vatican Advanced Technology Telescope, we detect a total of 1335 (FUV-selected) and 1474 (H$\alpha$-selected) regions of recent high-mass star formation, respectively. We find the H$\alpha$-to-FUV SFR ratios tend to be lower primarily for FUV-selected regions, where SFR$_{H\alpha}$ generally underestimates the SFR by an average factor of 2-3, for SFR $<$ 10$^{-4}$ M$_{\odot}$ yr$^{-1}$. In contrast, the SFRs are generally observed to be consistent for H$\alpha$-selected regions. This discrepancy arises from morphological differences between the two indicators. Extended FUV morphologies and larger areas covered by FUV-only regions, along with decreasing overlap between FUV clumps and compact HII regions with $R/R_{25}$ suggest that stochastic sampling of the initial mass function may be more pronounced in the outer regions of galaxies. Our observed H$\alpha$-to-FUV SFR ratios are also consistent with stochastic star formation model predictions. However, using larger apertures that include diffuse FUV emission results in an offset of 1 dex between SFR$_{H\alpha}$ and SFR$_{UV}$. This suggests that the observed low H$\alpha$-to-FUV SFR ratios in galaxies are likely caused by diffuse FUV emission, which can contribute $\sim$60-90\% to the total FUV flux.