The Impact of Dust on the Sizes of Galaxies in the Epoch of Reionization
The Impact of Dust on the Sizes of Galaxies in the Epoch of Reionization
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再电离时期尘埃对星系大小的影响
DOI：
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发表时间：
2021
影响因子：
4.8
通讯作者：
R. Croft
中科院分区：
文献类型：
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作者：
M. Marshall;S. Wilkins;T. Matteo;W. Roper;A. Vijayan;Y. Ni;Yu Feng;R. Croft
我们研究了再电离时期星系的大小，使用了来自BlueTides宇宙学流体动力学模拟从z = 7到11的约10万个星系的样本。我们从恒星质量和光度图中测量星系大小，将有效半径定义为可以包围图像中包含总质量/光的50%的像素的最小半径。我们发现恒星质量和有效半质量半径之间呈反比关系，这表明质量最大的星系比质量分布更平坦的低质量星系更紧凑、密度更大。我们发现固有远紫外光度与尺寸之间存在轻微的负相关关系，而从尘埃衰减图像中测量时，我们发现尺寸与光度呈正相关关系。这表明尘埃是观测到的正尺寸-光度关系的主要原因，尘埃优先衰减明亮的视线，导致更平坦的发射轮廓，从而更大的测量有效半径。我们研究了静幅紫外光谱和光学光谱的尺寸-光度关系，发现在较长的波长处斜率减小；这是由尘埃引起的关系的结果，尘埃在较长的波长下产生较少的衰减。我们发现远紫外光谱的尺寸-光度关系从z = 7到11呈现温和的演化，星系的尺寸随红移的变化而演化，R∝(1 + z)−m，其中m = 0.662±0.009。最后，我们研究了z = 7类星体宿主星系的尺寸，发现类星体宿主的固有尺寸相对于整个星系样本来说很小，但从尘埃衰减图像中测量它们的尺寸是相当的。
We study the sizes of galaxies in the Epoch of Reionization using a sample of ∼100, 000 galaxies from the BlueTides cosmological hydrodynamical simulation from z = 7 to 11. We measure the galaxy sizes from stellar mass and luminosity maps, defining the effective radius as the minimum radius which could enclose the pixels containing 50% of the total mass/light in the image. We find an inverse relationship between stellar mass and effective half-mass radius, suggesting that the most massive galaxies are more compact and dense than lower mass galaxies, which have flatter mass distributions. We find a mildly negative relation between intrinsic far-ultraviolet luminosity and size, while we find a positive size–luminosity relation when measured from dust-attenuated images. This suggests that dust is the predominant cause of the observed positive size–luminosity relation, with dust preferentially attenuating bright sight lines resulting in a flatter emission profile and thus larger measured effective radii. We study the size–luminosity relation across the rest-frame ultraviolet and optical, and find that the slope decreases at longer wavelengths; this is a consequence of the relation being caused by dust, which produces less attenuation at longer wavelengths. We find that the far-ultraviolet size–luminosity relation shows mild evolution from z = 7 to 11, and galaxy size evolves with redshift as R∝(1 + z)−m, where m = 0.662 ± 0.009. Finally, we investigate the sizes of z = 7 quasar host galaxies, and find that while the intrinsic sizes of quasar hosts are small relative to the overall galaxy sample, they have comparable sizes when measured from dust-attenuated images.