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arXiv 1503.07879astro-ph.GA
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Galerkin密度场估计的比较研究：对COSMOS中Galerkin随环境演化的新认识

A Comparative Study of Density Field Estimation for Galaxies: New Insights into the Evolution of Galaxies with Environment in COSMOS out to z~3

Behnam Darvish, Bahram Mobasher, David Sobral, Nicholas Scoville, Miguel Aragon-Calvo

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20 pages, 11 figures, main figures 4,5,8 and 10
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摘要：

众所周知，星系环境对星系性质的形成有着根本性的影响。我们研究了环境对星系演化的影响，重点是定义为星系局域数密度的环境。密度场估计与不同的估计（加权自适应核平滑，10 $^{th}$和5 $^{th}$最近的邻居，Voronoi和Delaunay镶嵌）为K $_{s}<$ 24样本的$\sim$ 190，000星系在0.1 $<$ z $<$ 3.1的COSMOS领域。每个估计器的性能进行了评估与广泛的模拟。我们表明，总体而言，有一个很好的协议之间的估计密度场使用不同的方法超过$\sim$ 2 dex的超密度值。然而，我们的模拟表明，自适应内核和Voronoi镶嵌优于其他方法。使用Voronoi曲面细分方法，我们分配表面密度的质量完整的样本的静止和恒星形成星系的z $\sim$ 3。我们表明，在一个固定的恒星质量，静止星系的中值颜色不依赖于他们的主机环境到z $\sim$ 3。我们发现，大质量（$>$ 10 $^{11}$ M $_{\odot}$）恒星形成星系的数量和恒星质量密度没有显着变化，因为z $\sim$ 3，无论他们的环境。然而，在较低的红移（z $\lesssim$ 1.3）的大规模的静态系统，我们发现一个显着的演变在密集的环境中的数量和恒星质量密度相比，较低的密度区域。我们的研究结果表明，恒星质量和局部密度之间的关系是更根本的颜色密度关系，环境中起着显着的作用，淬火恒星形成活动的星系在z $\lesssim$ 1。

英文摘要：

It is well-known that galaxy environment has a fundamental effect in shaping its properties. We study the environmental effects on galaxy evolution, with an emphasis on the environment defined as the local number density of galaxies. The density field is estimated with different estimators (weighted adaptive kernel smoothing, 10$^{th}$ and 5$^{th}$ nearest neighbors, Voronoi and Delaunay tessellation) for a K$_{s}<$24 sample of $\sim$190,000 galaxies in the COSMOS field at 0.1$<$z$<$3.1. The performance of each estimator is evaluated with extensive simulations. We show that overall, there is a good agreement between the estimated density fields using different methods over $\sim$2 dex in overdensity values. However, our simulations show that adaptive kernel and Voronoi tessellation outperform other methods. Using the Voronoi tessellation method, we assign surface densities to a mass complete sample of quiescent and star-forming galaxies out to z$\sim$3. We show that at a fixed stellar mass, the median color of quiescent galaxies does not depend on their host environment out to z$\sim$3. We find that the number and stellar mass density of massive ($>$10$^{11}$M$_{\odot}$) star-forming galaxies have not significantly changed since z$\sim$3, regardless of their environment. However, for massive quiescent systems at lower redshifts (z$\lesssim$1.3), we find a significant evolution in the number and stellar mass densities in denser environments compared to lower density regions. Our results suggest that the relation between stellar mass and local density is more fundamental than the color-density relation and that environment plays a significant role in quenching star formation activity in galaxies at z$\lesssim$1.

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