Galaxy Halo Assembly Bias

Galaxy Halo 装配偏差

• 批准号: 1795517
• 金额: --
• 依托单位: University of St Andrews
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1795517
• 关键词: Galaxy; Halo; Assembly; Bias

The large scale structure observable today requires an additional influencing factor over the homogenous and isotropic paradigm given by the Friedmann-Lemaitre-Robertson-Walker metric. Quantum perturbations in the early Universe can become macroscopic through inflation, leaving regions of over-density in the matter field. A requirement of galaxy formation is that we need a far greater gravitational potential than can be given through the amount of 'baryonic' matter we observe today. This naturally leads to the suggestion that instead pressureless matter drives the Universe's expansion and structure growth. Over-densities in causal contact grow linearly through perturbation theory, however some regions can grow non-linearly leading to eventual collapse into halos. Assumed to be composed of dark matter, these halos provide an excellent environment for structure growth, such as galaxies, since the gravitational collapse balances the random motions of the contained particles. Small halos form earlier and then can grow through a series of hierarchical merging. Halo growth is however deeply dependent on the larger geometric environment of the cosmic web which encompasses them. Regions of the cosmic web can be classified as a series of voids, filaments, sheets or knots (e.g. Eardley et al. 2015, Joachimi et al. 2016) depending on the number of dimensions seen to be in gravitational collapse. Knots, observable as galaxy clusters, are collapsing in three dimensions and produce strong tidal forces affecting the growth of smaller surrounding halos, for example. The characteristic properties of observable galaxies therefore are thought to be inherently linked to both their surrounding halo environment and the geometric environment they reside in. Identifying galaxy features which imply the attributes and history of the halo, however, are often subtle and hence require careful statistical analysis of data-rich surveys. In particular assembly bias corresponds to the theory that for halos of the same mass; earlier forming halos are more strongly clustered than their later forming counterparts. This previously has been detected through finding that central galaxies with a lower specific star formation rate, and therefore are older, typically cluster more than those with active star formation for a given total stellar mass (e.g. Wang et al. 2013). Due to the obvious obstacle of dark matter being electromagnetically invisible, reconstructing a halo's past requires a combination of innovative approaches.Current (MaNGA (SDSS-IV)) and future (DESI and Euclid) surveys promise the data-rich framework that such analyses require. The first aim of this project is to link the kinematic properties of individual galaxy components, such as stars and gas, to the kinematics of the surrounding dark matter halo. Due to the difference in post-merger relaxation timescales of gas and stars, their rotational misalignment may be able to act as a primer on halo age and therefore a further test of assembly bias. Training Completed:STFC Summer SchoolTutoring and Demonstrating in the Sciences: An introductionAssessment & Academic Misconduct (Science): An introductionPostgraduate Researcher Induction (all disciplines)Postgraduate Researcher EssentialsDiversity in the Workplace Online Training Module September 2016Class Rep training for PG repsTraining in process / to be completed:SUPA Induction SUPA Graduate School (20 hours core skills / 40 hours physics learning including: Advanced Data Analysis (Semester 1), Observing Course (Semester 2)) MaNGA conference and new student school in ShanghaiTelescope training trip at Teide Observatory, Tenerife

今天可观察到的大尺度结构需要在Friedmann-Lemaitre-Robertson-Walker度规给出的均匀和各向同性范式上增加一个影响因素。早期宇宙中的量子扰动可以通过暴胀变得宏观，在物质场中留下过密度区域。星系形成的一个必要条件是，我们需要一个比我们今天观测到的“重子”物质所能提供的引力势大得多的引力势。这自然会导致这样的建议，即无压物质驱动宇宙的膨胀和结构增长。因果接触中的过密度通过微扰理论线性增长，然而某些区域可以非线性增长，最终导致坍缩成晕。假设由暗物质组成，这些晕为结构生长提供了极好的环境，例如星系，因为引力坍缩平衡了包含粒子的随机运动。小晕形成较早，然后可以通过一系列的层次合并增长。然而，光环的生长深深依赖于包围它们的宇宙网的更大几何环境。宇宙网的区域可以被分类为一系列的空隙，细丝，片或结（例如Eardley et al. 2015，Joachimi et al. 2016），这取决于在引力坍缩中看到的维度的数量。例如，可观察到的星系团结在三维空间中坍缩，并产生强大的潮汐力，影响周围较小的晕的生长。因此，可观测星系的特性被认为与它们周围的晕环境和它们所处的几何环境有着内在的联系。然而，识别暗示晕的属性和历史的星系特征往往是微妙的，因此需要对数据丰富的调查进行仔细的统计分析。特别是大会的偏见对应的理论，晕相同的质量，早期形成的晕更强烈的集群比他们后来形成的同行。这以前已经通过发现具有较低特定星星形成率的中心星系被发现，因此对于给定的总恒星质量，它们通常比那些具有活跃星星形成的星系更古老，通常聚集更多（例如Wang et al. 2013）。由于暗物质在电磁场上是不可见的，这是一个明显的障碍，重建晕的过去需要结合创新的方法。当前的（MaNGA（SDSS-IV））和未来的（DESI和欧几里得）调查保证了这种分析所需的数据丰富的框架。该项目的第一个目标是将单个星系组成部分（如恒星和气体）的运动学特性与周围暗物质晕的运动学联系起来。由于气体和恒星在合并后弛豫时间尺度上的差异，它们的旋转错位可能能够作为晕年龄的引物，因此是对组装偏差的进一步测试。培训完成：STFC暑期学校辅导和演示在科学：介绍评估和学术不端行为（科学）：介绍研究生研究员入职（所有学科）研究生研究员课程工作场所的多样性在线培训模块2016年9月PG代表的班级代表培训正在进行/待完成：SUPA入职SUPA研究生院（20小时核心技能/ 40小时物理学习，包括：高级数据分析（第1学期），观察课程（第二学期）MaNGA会议和上海的新生学校望远镜培训之旅在特内里费岛的泰德天文台

项目成果

SDSS-IV MaNGA: signatures of halo assembly in kinematically misaligned galaxies

• DOI: 10.1093/mnras/sty3101
• 发表时间: 2018-11
• 期刊: Monthly Notices of the Royal Astronomical Society
• 影响因子: 4.8
• 作者: Christopher Duckworth;R. Tojeiro;K. Kraljic;M. Sgr'o;V. Wild;A. Weijmans;I. Lacerna;N. Drory

The Fifteenth Data Release of the Sloan Digital Sky Surveys: First Release of MaNGA-derived Quantities, Data Visualization Tools, and Stellar Library

• DOI: 10.3847/1538-4365/aaf651
• 发表时间: 2018-12
• 期刊: The Astrophysical Journal Supplement Series
• 作者: D. Aguado;Romina Ahumada;Andr'es Almeida;S. Anderson;B. Andrews;B. Anguiano;E. Ort́ız;A. Aragón-Sa

Overview of the DESI Legacy Imaging Surveys

DESI 传统成像调查概述

• DOI: 10.3847/1538-3881/ab089d
• 发表时间: 2019-05-01
• 期刊: ASTRONOMICAL JOURNAL
• 影响因子: 5.3
• 作者: Dey, Arjun;Schlegel, David J.;Zhou, Zhimin
• 通讯作者: Zhou, Zhimin