[abridged] We analyze a sample of 9 massive clusters at 0.4<z<0.6 observed with MegaCam in 4 photometric bands (g,r,i,z) from the core to a radius of 5 Mpc (~4000 galaxies). Galaxy cluster candidates are selected using photometric redshifts computed with HyperZ. Morphologies are estimated with galSVM in two broad morphological types (early-type and late-type). We examine the morphological composition of the red-sequence and the blue-cloud and study the relations between galaxies and their environment through the morphology-density relations (T-Sigma) and the morphology-radius relation (T-R) in a mass limited sample (log(M/Msol)>9.5). We find that the red sequence is already in place at z~0.5 and it is mainly composed of very massive (log(M/Msol)>11.3) early-type galaxies. These massive galaxies seem to be already formed when they enter the cluster, probably in infalling groups, since the fraction remains constant with the cluster radius. Their presence in the cluster center could be explained by a segregation effect reflecting an early assembly history. Any evolution that takes place in the galaxy cluster population occurs therefore at lower masses (10.3<log(M/Msol)<11.3). For these galaxies, the evolution, is mainly driven by galaxy-galaxy interactions in the outskirts as revealed by the T-Sigma relation. Finally, the majority of less massive galaxies (9.5<log(M/Msol)<10.3) are late-type galaxies at all locations, suggesting that they have not started the morphological transformation yet even if this low mass bin might be affected by incompleteness.
Morphological Signatures of Gravitational Evolution, Redshift-Space Distortions, and Massive Neutrinos in Large-Scale Structure
Korea Institute for Advanced Study (KIAS)(韩国高等科学研究院);Asia Pacific Center for Theoretical Physics(亚太理论物理中心);Department of Physics, POSTECH(浦项科技大学物理系);Indian Institute of Astrophysics(印度天体物理研究所)
Listening to galaxies tuning at z ~ 2.5 - 3.0: The first strikes of the Hubble fork
我们调查的494个星系从GMASS调查中选择在z>1,主要是在其光学静止框架,使用HST图像,从CANDELS调查的形态学特性。我们认为哈勃序列的星系形态在红移2.5<z 1时形成<3. The fractions of both ellipticals and disks decrease with increasing lookback time at z>,因此在红移z=2.5-2.7及以上时,哈勃类型无法识别,大多数星系被归类为不规则星系。定量形态学分析表明,在1<z<3时,形态学参数在区分不同形态的哈勃类型时不如在低红移时有效。没有显着的形态k-校正被发现需要哈勃类型的分类,有一些例外。一般来说,不同的形态类型占据了星系的静止坐标系(U-B)色双峰的两个峰:大多数不规则星系占据蓝峰,而椭圆星系主要位于红峰,尽管有一定程度的污染。椭圆星系比不规则星系和椭圆星系分布更均匀。我们发现,在UVJ图中的星系的位置是有关其形态类型:“静止”的绘图区域主要是由椭圆形,并在较小程度上,由磁盘。我们发现,在我们的样本中,只有~33%的所有形态椭圆星系是红色和被动演化的星系。形态上被归类为椭圆星系的蓝色星系与红色星系有着显著的结构相似性。几乎所有的不规则星系都有一个恒星形成的星系光谱。此外,大多数盘在其光谱中显示出恒星形成活动的迹象,尽管在某些情况下,它们的红色连续谱表明了…
A Closer Look at the Dynamical State of the High-redshift Galaxy Cluster SPT-CL J2215-3537
Observatório Nacional(国家天文台);Department of Astronomy, University of Michigan(密歇根大学天文学系);Instituto de Astrofísica de Andalucía–CSIC(安达卢西亚天体物理研究所-西班牙国家研究委员会)
Approximate Bayesian Computation for Astronomical Model Analysis: A Case Study in Galaxy Demographics and Morphological Transformation at High Redshift
“近似贝叶斯计算”(ABC)代表了一种用于分析复杂随机系统的强大方法,对于该复杂随机系统,在任意输入参数集下观察到的数据的似然性可能是完全难以处理的-后一种情况使得基于易处理似然性的贝叶斯统计推断(例如,常规马尔可夫链蒙特卡罗模拟; MCMC)的标准机器无用。在这篇文章中,我们展示了潜在的ABC天文模型分析的应用程序在高红移星系的形态转变的案例研究。为此,首先,我们发展了一个早期宇宙中合并和长期演化竞争过程的随机模型;其次,通过与CANDELS/EGS数据集中观测到的大质量(M_gal > 10^11 M_sun)星系(在1.5 < z < 3)的人口统计数据进行基于ABC的比较,我们推导出该模型关键参数的后验概率密度。本文展示的ABC的“顺序蒙特卡罗”(SMC)实现,具有自生成的目标序列和自细化MCMC内核,是这一重要统计算法的最有效的当代方法之一。我们强调,以及通过我们所选择的案例研究的价值,仔细的汇总统计选择,并展示了两个现代战略的评估和优化在这方面。最终,我们的ABC分析高红移形态的混合回报严格的限制在早期宇宙的合并率的演变,有利于主要合并(与光盘生存或快速改造)的长期演变的机制,最负责建立在早期型磁盘的第一代凸起。
ZENS IV. Similar Morphological Changes associated with Mass- and Environment-Quenching, and the Relative importance of Bulge Growth versus the Fading of Disks
Stellar velocity dispersion of Luminous Compact Galaxies at intermediate redshift
本文给出了5个发光致密星系(LCG)在z=0.5-0.7范围内的恒星速度色散测量结果。这些星系正在活跃地形成恒星,平均SFR $\sim$为40 M $_{\odot}$ /年。我们发现它们的速度色散范围从$\sim137\ \rm{km/s}$到$260\ \rm{km/s}$,而它们的恒星质量范围从$4\times 10^{9}$到$10^{11}$ M $_{\odot}$。如果这些LCG在恒星形成的大爆发之后被动地演化,它们的质量和速度色散,以及它们演化的颜色和光度与今天早期螺旋星系的特征值最一致。
The SRG/eROSITA all-sky survey: The morphologies of clusters of galaxies: II. The intrinsic distributions of morphological parameters
Max-Planck-Institut für extraterrestrische Physik(马克斯·普朗克地外物理学研究所);IRAP, CNRS, UPS, CNES(法国国家科学研究中心/图卢兹第三大学/欧洲空间局天体物理研究所);Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University(北京师范大学天文与前沿科学研究院);Argelander-Institut für Astronomie (AIfA), Universität Bonn(波恩大学阿尔兰德尔天文学研究所)
Morphological Bias: How Ellipticals and Spirals Trace the Cosmic Web Differently
Institute of Astronomy, School of Physics, Zhejiang University(浙江大学物理学院天体物理研究所);Center for Cosmology and Computational Astrophysics, Institute for Advanced Study in Physics, Zhejiang University(浙江大学物理高等研究院宇宙学与计算天体物理中心);Observatório Nacional(国家天文台)
Quantifying Weighted Morphological Content of Large-Scale Structures via Simulation-Based Inference
Department of Physics, Shahid Beheshti University(沙希德·贝赫什提大学物理系);School of Physics, Institute for Research in Fundamental Sciences (IPM)(基础科学研究所(IPM)物理学院);School of Astronomy, Institute for Research in Fundamental Sciences (IPM)(基础科学研究所(IPM)天文学院);Department of Mathematics and Statistics, The University of Lahore(拉合尔大学数学与统计系)