Testing the Recovery of Intrinsic Galaxy Sizes and Masses of z ∼ 2 Massive Galaxies Using Cosmological Simulations
Testing the Recovery of Intrinsic Galaxy Sizes and Masses of z ∼ 2 Massive Galaxies Using Cosmological Simulations
复制标题
使用宇宙学模拟测试 z 〜 2 大质量星系的本征星系尺寸和质量的恢复
DOI：
10.3847/2041-8213/aa7d4b
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
G. Barro
中科院分区：
文献类型：
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作者：
S. Price;M. Kriek;R. Feldmann;E. Quataert;P. Hopkins;C. Faucher;D. Keres̆;G. Barro
精确测量星系的质量和大小是追踪星系随时间演化的关键。宇宙学放大模拟提供了一个理想的测试平台，用于评估从观测中恢复星系属性。在这里，我们利用星系在z = 1.7-2从大规模火灾宇宙学模拟套件，在现实环境中的反馈（火）项目的一部分。使用模拟多波段图像，我们比较固有的星系质量和大小的观测估计。我们发现，观测准确地恢复恒星质量，轻微的平均低估和分散。当在所有视角上取平均值时，半光半径与固有半质量半径一致，系统偏移为（半光半径较大），散射为。当使用颜色梯度来解释质量到光的变化时，恢复的半质量半径也超过固有的半质量半径。然而，如果不适当地考虑，孔径效应可以使尺寸估计产生偏差。恒星形成星系和静止星系的质量和大小偏移之间没有差异。视角的变化是造成恢复的质量和尺寸中的25%的散射的原因。因此，我们的研究结果表明，在质量大小关系的内在散射可能被高估了25%。此外，方向驱动散射导致超大质量星系的数密度被高估。
Accurate measurements of galaxy masses and sizes are key to tracing galaxy evolution over time. Cosmological zoom-in simulations provide an ideal test bed for assessing the recovery of galaxy properties from observations. Here, we utilize galaxies with at z ∼ 1.7–2 from the MassiveFIRE cosmological simulation suite, part of the Feedback in Realistic Environments (FIRE) project. Using mock multi-band images, we compare intrinsic galaxy masses and sizes to observational estimates. We find that observations accurately recover stellar masses, with a slight average underestimate of and scatter. Recovered half-light radii agree well with intrinsic half-mass radii when averaged over all viewing angles, with a systematic offset of (with the half-light radii being larger) and a scatter of . When using color gradients to account for mass-to-light variations, recovered half-mass radii also exceed the intrinsic half-mass radii by . However, if not properly accounted for, aperture effects can bias size estimates by . No differences are found between the mass and size offsets for star-forming and quiescent galaxies. Variations in viewing angle are responsible for ∼25% of the scatter in the recovered masses and sizes. Our results thus suggest that the intrinsic scatter in the mass–size relation may have previously been overestimated by ∼25%. Moreover, orientation-driven scatter causes the number density of very massive galaxies to be overestimated by at .