用H $α$和叠加GALEX UV成像观测星系棒中恒星形成的分布
The distribution of star formation in galactic bars as seen with H$α$ and stacked GALEX UV imaging
摘要：
我们研究了S $^4$ G巡天中邻近盘状星系条（倾角为$< 65^{\circ}$）内恒星形成（SF）的空间分布。我们使用档案GALEX远紫外和近紫外成像772棒星系。我们还汇编了433个棒星系的连续减影H $α$图像，其中70个是由我们自己从辅助测光和MUSE/CALIFA IFU数据立方体。我们采用了两种互补的方法：i）的酒吧/磁盘堆栈的分析，建立从共同添加的UV图像的数百个星系;和ii）的形态分类的电离区域的星系分为三个主要的SF类：A）只有环核SF，B）SF在酒吧的两端，但不是沿着酒吧，和C）SF沿着酒吧。透镜状星系通常属于SF A类：这可能与棒引起的SF淬火有关。早期和中期型螺旋的SF B类峰的分布：这最有可能是由于气体流，冲击和增强的剪切在中央集中的星系与大酒吧振幅的相互作用。晚型星系主要被分配到SF C类：我们认为，这是一个低剪切的后果。在螺旋形的棒堆中，紫外线辐射跟踪恒星棒，并在它们的前侧占主导地位，正如模拟中所见。对于早期类型，强棒星系的中心紫外线辐射比弱棒星系亮$\sim$ 0.5等：这与强棒扫过盘气体并触发中心星爆的效率有关。我们还表明，SF的分布在内环星系是大致相同的酒吧和非酒吧星系，包括紫外/H $α$赤字的中间部分的酒吧：这暗示在共振环捕获气体的效果。在不同形态类型的星系中，有报道称棒内的SF分布不同（节略）。
英文摘要：
We investigate the spatial distribution of star formation (SF) within bars of nearby disk galaxies (inclination $< 65^{\circ}$) from the S$^4$G survey. We use archival GALEX far- and near-UV imaging for 772 barred galaxies. We also assemble a compilation of continuum-subtracted H$α$ images for 433 barred galaxies, of which 70 are produced by ourselves from ancillary photometry and MUSE/CALIFA IFU data cubes. We employ two complementary approaches: i) the analysis of bar/disk stacks built from co-added UV images of hundreds of galaxies; and ii) the classification of the morphology of ionised regions in galaxies into three main SF classes: A) only circumnuclear SF, B) SF at the bar ends, but not along the bar, and C) SF along the bar. Lenticular galaxies typically belong to SF class A: this is probably related to bar-induced SF quenching. The distribution of SF class B peaks for early- and intermediate-type spirals: this most likely results from the interplay of gas flow, shocks, and enhanced shear in centrally concentrated galaxies with large bar amplitudes. Late-type galaxies are mainly assigned to SF class C: we argue that this is a consequence of low shear. In bar stacks of spirals, the UV emission traces the stellar bars and dominates on their leading side, as witnessed in simulations. For early-types, the central UV emission is $\sim$0.5 mag brighter in strongly barred galaxies, relative to their weakly barred counterparts: this is related to the efficiency of strong bars sweeping the disk gas and triggering central starbursts. We also show that the distributions of SF in inner ringed galaxies are broadly the same in barred and non-barred galaxies, including a UV/H$α$ deficit in the middle part of the bar: this hints at the effect of resonance rings trapping gas. Distinct distributions of SF within bars are reported in galaxies of different morphological types (Abridged).
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