Clustering Properties of Far-Infrared Sources in Hi-GAL Science Demonstration Phase Fields
N. Billot, E. Schisano, M. Pestalozzi, S. Molinari, A. Noriega-Crespo, J. C. Mottram, L. D. Anderson, D. Elia, G. Stringfellow, M. A. Thompson, D. Polychroni, L. Testi
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17 pages, 9 figures, accepted for publication in ApJ
We use a Minimum Spanning Tree algorithm to characterize the spatial distribution of Galactic Far-IR sources and derive their clustering properties. We aim to reveal the spatial imprint of different types of star forming processes, e.g. isolated spontaneous fragmentation of dense molecular clouds, or events of triggered star formation around HII regions, and highlight global properties of star formation in the Galaxy. We plan to exploit the entire Hi-GAL survey of the inner Galactic plane to gather significant statistics on the clustering properties of star forming regions, and to look for possible correlations with source properties such as mass, temperature or evolutionary stage. In this paper we present a pilot study based on the two 2x2 square degree fields centered at longitudes l=30 and l=59 obtained during the Science Demonstration Phase (SDP) of the Herschel mission. We find that over half of the clustered sources are associated with HII regions and infrared dark clouds. Our analysis also reveals a smooth chromatic evolution of the spatial distribution where sources detected at short-wavelengths, likely proto-stars surrounded by warm circumstellar material emitting in the far-infrared, tend to be clustered in dense and compact groups around HII regions while sources detected at long-wavelengths, presumably cold and dusty density enhancements of the ISM emitting in the sub-millimeter, are distributed in larger and looser groups.
Color dependence of clustering of massive galaxies at 0.5$\le z \le$2.5: similar spatial distributions between green valley galaxies and AGNs
我们提出了一个在宇宙/UltraVISTA领域的$0.5\le z \le 2.5$的静止帧UV选择的大质量星系的空间聚类的测量。考虑到四个独立的红移仓与$Δz=0.5$，我们构建了三个星系种群，即，红序列（RS），蓝云（BC）和绿谷（GV）星系，根据他们的休息帧消隐校正的紫外线颜色。这些人口的相关长度被证实是依赖于他们的休息帧的紫外线颜色和红移：紫外线红星系被发现是更集群。在所有的红移仓中，GV星系的聚集幅度一般都是中等的，并且聚集在质量介于RS和BC星系之间的暗物质晕中;在同一个红移仓中，GV星系的聚集幅度与活动星系核的聚集幅度接近，这表明活动星系核的活动可能是改变星系颜色的原因。在仔细研究了它们的恒星质量后，我们发现，当不同颜色的星系样本具有相似的恒星质量中值时，它们的成团幅度都是相似的，并且恒星质量中值本身可能是一个很好的星系成团的预测因子。
Galaxy And Mass Assembly (GAMA): the signatures of galaxy interactions as viewed from small scale galaxy clustering
星系-星系相互作用的统计研究经常利用祖先物理性质的净变化作为其核之间的分离的函数来追踪其相互作用的强度和可观察的时间尺度。在这项研究中，我们使用两点自动，交叉和标记关联函数调查在何种程度上的小尺度成团性质的恒星形成的星系可以用来获得物理洞察星系星系之间的相互作用的相似的光学亮度和恒星质量。从高度空间完整的星系和质量组装（GAMA）调查中得出的Halalpha恒星形成者显示，在小的分离上集群增加。此外，成团强度与光学亮度和恒星质量有很强的相关性，其中（1）在给定的距离下，光学较亮的星系成团幅度大于光学较暗的星系，（2）小尺度成团特性（例如强度，恒星形成星系的信号相对于基准幂律平台（fiducial power law plateaus）的尺度似乎随着星系光学亮度的增加而不同。根据交叉和标记相关分析，前一个结果在很大程度上是由光学明亮的恒星形成星系中增加的尘埃含量驱动的。后者可以被解释为相互作用尺度和星系光学亮度之间的相关性的证据，其中光学明亮的恒星形成者之间的相互作用的物理证据，可能托管在相对大质量的晕中，比光学暗淡的恒星形成者之间的分离更大。
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Modeling the clustering and halo occupation distribution of BOSS-CMASS galaxies in the Final Data Release
Galaxy Clustering Can Reveal Host-Galaxy Properties of Binary Black Hole Mergers
Research Center for the Early Universe (RESCEU), Graduate School of Science, The University of Tokyo（东京大学理学研究系早期宇宙研究中心）；TAPIR, California Institute of Technology（加州理工学院 TAPIR）；Graduate School of Science, The University of Tokyo（东京大学理学研究系）；Department of Physics, Graduate School of Science, Chiba University（千叶大学理学研究系物理学科）
