Mapping Metallicity Variations across Nearby Galaxy Disks
Mapping Metallicity Variations across Nearby Galaxy Disks
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DOI：
10.3847/1538-4357/ab5115
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
K. Kreckel;I. Ho;G. Blanc;G. Blanc;B. Groves;B. Groves;F. Santoro;E. Schinnerer;F. Bigiel
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文献类型：
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作者：
K. Kreckel;I. Ho;G. Blanc;G. Blanc;B. Groves;B. Groves;F. Santoro;E. Schinnerer;F. Bigiel
星系中金属的分布可以追溯到重子循环和星系盘的形成，但详细的气相金属丰度分布仍然很少采样。作为PHANGS-MUSE巡天的一部分，我们利用甚大望远镜/多单位光谱探测器（MUSE）光学积分场光谱测定了邻近8个星系圆盘上7138个H ii区域的气相氧丰度。在去除每个星系中存在的一阶径向梯度后，我们查看金属丰度偏移量的统计数据（ΔO/H）并探索方位角变化。在每个星系中，我们发现在任何给定的半径下，散射都很低（σ = 0.03-0.05指数），这表明了有效的混合。我们比较了那些为1σ异常值的氢区在丰度增强和丰度降低方面的物理参数。丰度增强的区域电离参数高，Hα光度高，Hα速度色散低，星团年轻，相关分子气体云分子气体密度高。这表明最近的恒星形成在局部丰富了物质。丰度降低的区域显示出更高的Hα速度色散，表明混合引入了更多的原始物质。我们在一半的样本中观察到细微的方位角变化，但不能总是将其与螺旋图案清晰地联系起来。丰度增强和减少的区域分布在整个圆盘上，在我们一半的星系中，我们可以识别出与金属丰度梯度明显相关的旋臂的亚部分。这表明旋臂在组织和混合星际介质方面发挥了作用。
The distribution of metals within a galaxy traces the baryon cycle and the buildup of galactic disks, but the detailed gas phase metallicity distribution remains poorly sampled. We have determined the gas phase oxygen abundances for 7138 H ii regions across the disks of eight nearby galaxies using Very Large Telescope/Multi Unit Spectroscopic Explorer (MUSE) optical integral field spectroscopy as part of the PHANGS–MUSE survey. After removing the first-order radial gradients present in each galaxy, we look at the statistics of the metallicity offset (ΔO/H) and explore azimuthal variations. Across each galaxy, we find low (σ = 0.03–0.05 dex) scatter at any given radius, indicative of efficient mixing. We compare physical parameters for those H ii regions that are 1σ outliers toward both enhanced and reduced abundances. Regions with enhanced abundances have high ionization parameter, higher Hα luminosity, lower Hα velocity dispersion, younger star clusters, and associated molecular gas clouds showing higher molecular gas densities. This indicates recent star formation has locally enriched the material. Regions with reduced abundances show increased Hα velocity dispersions, suggestive of mixing introducing more pristine material. We observe subtle azimuthal variations in half of the sample, but cannot always cleanly associate this with the spiral pattern. Regions with enhanced and reduced abundances are found distributed throughout the disk, and in half of our galaxies we can identify subsections of spiral arms with clearly associated metallicity gradients. This suggests spiral arms play a role in organizing and mixing the interstellar medium.