The 2D metallicity distribution and mixing scales of nearby galaxies
The 2D metallicity distribution and mixing scales of nearby galaxies
复制标题
邻近星系的二维金属丰度分布和混合尺度
DOI：
10.1093/mnras/stab3082
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发表时间：
2021
影响因子：
4.8
通讯作者：
Chevance, Mélanie
中科院分区：
文献类型：
--
作者：
Williams, Thomas G;Kreckel, Kathryn;Belfiore, Francesco;Groves, Brent;Sandstrom, Karin;Santoro, Francesco;Blanc, Guillermo A;Bigiel, Frank;Boquien, Médéric;Chevance, Mélanie
了解星系内金属的空间分布使我们能够研究星际介质中的化学富集和混合过程。在这项工作中，我们使用高斯过程回归（GPR）为19个恒星形成星系观测到的超大望远镜/多单元光谱探测器（VLT-MUSE）作为PHANGS-MUSE调查的一部分，映射金属的二维分布。我们发现，我们的19个星系中有12个显示出显着的二维金属丰度变化。那些没有显著变化的星系通常有较少的金属丰度测量，表明这是由于这些星系中缺乏${\rm H\，{\small II}}$区域，而不是缺乏高阶变化。在减去线性径向梯度后，我们看到螺旋臂与盘相比没有富集。我们测量的50%的相关尺度从两点相关函数的径向减去这些地图，发现它通常是一个数量级小于拟合的GPR内核尺度长度。我们研究了两点关联标度长度与一些全局星系性质的依赖关系。我们发现50%的相关尺度和整体气体湍流之间没有关系，与现有的理论模型的紧张局势。我们还发现了更活跃的恒星形成星系，早期类型的星系有更大的50%相关尺度。大小和恒星质量表面密度似乎与50%的相关尺度无关，这表明也许星系的演化状态及其当前的星星形成活动是金属分布均匀性的最强指标。
Understanding the spatial distribution of metals within galaxies allows us to study the processes of chemical enrichment and mixing in the interstellar medium. In this work, we map the 2D distribution of metals using a Gaussian Process Regression (GPR) for 19 star-forming galaxies observed with the Very Large Telescope/Multi Unit Spectroscopic Explorer (VLT–MUSE) as a part of the PHANGS–MUSE survey. We find that 12 of our 19 galaxies show significant 2D metallicity variation. Those without significant variations typically have fewer metallicity measurements, indicating this is due to the dearth of ${\rm H\, {\small II}}$ regions in these galaxies, rather than a lack of higher-order variation. After subtracting a linear radial gradient, we see no enrichment in the spiral arms versus the disc. We measure the 50 per cent correlation scale from the two-point correlation function of these radially subtracted maps, finding it to typically be an order of magnitude smaller than the fitted GPR kernel scale length. We study the dependence of the two-point correlation scale length with a number of global galaxy properties. We find no relationship between the 50 per cent correlation scale and the overall gas turbulence, in tension with existing theoretical models. We also find more actively star-forming galaxies, and earlier type galaxies have a larger 50 per cent correlation scale. The size and stellar mass surface density do not appear to correlate with the 50 per cent correlation scale, indicating that perhaps the evolutionary state of the galaxy and its current star formation activity is the strongest indicator of the homogeneity of the metal distribution.