We investigate the origin of the relations between stellar mass and optical circular velocity for early-type (ETG) and late-type (LTG) galaxies --- the Faber-Jackson (FJ) and Tully-Fisher (TF) relations. We combine measurements of dark halo masses (from satellite kinematics and weak lensing), and the distribution of baryons in galaxies (from a new compilation of galaxy scaling relations), with constraints on dark halo structure from cosmological simulations. The principle unknowns are the halo response to galaxy formation and the stellar initial mass function (IMF). The slopes of the TF and FJ relations are naturally reproduced for a wide range of halo response and IMFs. However, models with a universal IMF and universal halo response cannot simultaneously reproduce the zero points of both the TF and FJ relations. For a model with a universal Chabrier IMF, LTGs require halo expansion, while ETGs require halo contraction. A Salpeter IMF is permitted for high mass (sigma > 180 km/s) ETGs, but is inconsistent for intermediate masses, unless V_circ(R_e)/sigma_e > 1.6. If the IMF is universal and close to Chabrier, we speculate that the presence of a major merger may be responsible for the contraction in ETGs while clumpy accreting streams and/or feedback leads to expansion in LTGs. Alternatively, a recently proposed variation in the IMF disfavors halo contraction in both types of galaxies. Finally we show that our models naturally reproduce flat and featureless circular velocity profiles within the optical regions of galaxies without fine-tuning.
Based on galaxies in the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) and dark matter haloes in the dark matter only, cosmological and constrained ELUCID simulation, we investigate the relation between the observed radii of central galaxies with stellar mass $\gtrsim 10^{8} h^{-2}{\rm M}_\odot$ and the virial radii of their host dark matter haloes with virial mass $\gtrsim 10^{10.5} h^{-1}{\rm M}_\odot$, and the dependence of galaxy-halo size relation on the halo spin and concentration. Galaxies in observation are matched to dark matter (sub-)haloes in the ELUCID simulation using a novel…
Do halos that form early, have high concentration, are part of a pair, or contain a central galaxy potential host more pronounced planes of satellite galaxies?
We provide a new constraint on the small-scale density fluctuations, evaluating the diffuse background free-free emission from dark matter halos in the dark ages. If there exists a large amplitude of the matter density fluctuations on small scales, the excess enhances the early formation of dark matter halos. When the virial temperature is sufficiently high, the gas in a halo is heated up and ionized by thermal collision. The heated ionized gas emits photons by the free-free process. We would observe the sum of these photons as the diffuse background free-free emission. Assuming the analytical…
We study the effect of self-interacting dark matter (SIDM) and baryons on the shape of early-type galaxies (ETGs) and their dark matter haloes, comparing them to the predictions of the cold dark matter (CDM) scenario. We use five hydrodynamical zoom-in simulations of haloes hosting ETGs ($M_{\rm vir}\sim 10^{13}M_{\odot}$ and $M_{*}\sim10^{11}M_{\odot}$), simulated in CDM and a SIDM model with constant cross-section of $σ_T/m_χ= 1\ \mathrm{cm}^2 \mathrm{g}^{-1}$. We measure the three-dimensional and projected shapes of the dark matter haloes and their baryonic content using the inertia tensor …
Halo assembly bias in the early Universe: a clustering probe of the origin of the Little Red Dots
Peking University(北京大学);Kavli Institute for Astronomy and Astrophysics, Peking University(北京大学科维理天文与天体物理研究所);Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology(麻省理工学院科维理天体物理与空间研究)
LCDM cosmological models with Early Dark Energy (EDE) have been proposed to resolve tensions between the Hubble constant H0 = 100h km/s/Mpc measured locally, giving h ~ 0.73, and H0 deduced from Planck cosmic microwave background (CMB) and other early universe measurements plus LCDM, giving h ~ 0.67. EDE models do this by adding a scalar field that temporarily adds dark energy equal to about 10% of the cosmological energy density at the end of the radiation-dominated era at redshift z ~ 3500. Here we compare linear and nonlinear predictions of a Planck-normalized LCDM model including EDE givin…
The halo assembly bias, a phenomenon referring to dependencies of the large-scale bias of a dark matter halo other than its mass, is a fundamental property of the standard cosmological model. First discovered in 2005 from the Millennium Run simulation, it has been proven very difficult to be detected observationally, with only a few convincing claims of detection so far. The main obstacle lies in finding an accurate proxy of the halo formation time. In this study, by utilizing a constrained simulation that can faithfully reproduce the observed structures larger than $2\,$Mpc in the local unive…
We use a robust analytical model together with a high-resolution hydrodynamical cosmological simulation to demonstrate that in a $Λ$ cold dark matter ($Λ$CDM) universe, a small fraction of dwarf galaxies inhabiting dark matter (DM) halos in the mass range $3\times 10^{9} \lesssim M_{200} / M_{\odot} \lesssim 10^{10}$ form unusually late ($z<3$) compared to the bulk population of galaxies. These galaxies originate from the interplay between the stochastic growth of DM halos and the existence of a time-dependent DM halo mass below which galaxies do not form. The formation epoch of the simulated …
If the formation of central galaxies in dark matter haloes traces the assembly history of their host haloes, in haloes of fixed mass, central galaxy clustering may show dependence on properties indicating their formation history. Such a galaxy assembly bias effect has been investigated by Lin et al. 2016, with samples of central galaxies constructed in haloes of similar mass and with mean halo mass verified by galaxy lensing measurements, and no significant evidence of assembly bias is found from the analysis of the projected two-point correlation functions of early- and late-forming central g…
Evolution of Stellar-to-Halo Mass Ratio at z=0-7 Identified by Clustering Analysis with the Hubble Legacy Imaging and Early Subaru/Hyper Suprime-Cam Survey Data
Dark Matter Contraction and the Stellar Content of Massive Early-type Galaxies: Disfavoring "Light" Initial Mass Functions
我们使用恒星动力学,强透镜,恒星星族合成模型,和弱透镜剪切测量约束的暗物质(DM)的配置文件和恒星质量在一个样本的53个大规模的早型星系。我们探索了三种DM晕模型(未扰动Navarro Frenk & White [NFW]晕和Blumenthal和Gnedin的绝热收缩模型),并对恒星和维里质量之间的关系施加了一个模型(即,作为晕质量函数的恒星形成效率的关系)。我们表明,考虑到我们的模型假设,数据显然更喜欢Salpeter样的初始质量函数(IMF),而不是更轻的IMF(例如,Chabrier或Kroupa),无论选择DM晕圈。此外,我们发现数据最多倾向于适度的绝热收缩(布卢门撒尔绝热收缩是强烈不受欢迎的),并且仅与无绝热收缩一致(即,NFW晕),如果假设一个质量依赖的IMF,在这个意义上,一个更大规模的正常化的IMF更大规模的晕。
Magnetic fields in extreme primordial halos: turbulent collapse and implications for early quasar formation
Hamburger Sternwarte, Universität Hamburg(汉堡天文台,汉堡大学);Dipartimento di Fisica, Sapienza Università di Roma(罗马智慧大学物理系);Physics Department, College of Science, United Arab Emirates University(阿拉伯联合酋长国大学理学院物理系)
In cosmologies with an early matter-dominated era (EMDE) prior to Big Bang nucleosynthesis, the boosted growth of small-scale matter perturbations during the EMDE leads to microhalo formation long before halos would otherwise begin to form. For a range of models, halos can even form during the EMDE itself. These halos would dissipate at the end of the EMDE, releasing their gravitationally heated dark matter and thereby imprinting a free-streaming cut-off on the matter power spectrum. We conduct the first cosmological $N$-body simulations of the formation and evaporation of halos during and aft…
Formation and Evolution of Early-Type Galaxies. III Star formation history as a function of mass and over-density
我们调查的初始原星系的过度密度和质量对它们的演化的影响,了解是否原星系晕的内部属性是足以说明银河系人口的不同属性。通过完全流体动力学N体模拟与代码EvoL进行,我们产生了12个自相似模型的早期类型的星系不同的初始质量和过密度,以下其从z \geq 20到z \leq 1的演变。模拟包括辐射冷却,恒星形成,恒星能量反馈,再电离光加热背景,和化学富集的ISM。我们发现一个很强的相关性之间的初始属性的原晕和他们的恒星形成的历史。大规模(10^13 M \odot)晕经历一次单一的、强烈的恒星形成爆发(\geq 10^3 M \odot /yr),与观测结果一致,对初始超密度的依赖性不太明显;中等质量(10 ^11 M \odot)晕的历史强烈地依赖于它们的初始超密度,而小的(10^9 M \odot)晕总是有着支离破碎的历史,由于“星系呼吸”现象,导致了多个恒星星族。星系模型具有与真实星系相当的形态、结构和光度特性,通常与观测数据密切匹配;尽管仍然存在一些分歧,可能是一些数值选择的结果。我们的结论是,内部属性基本上是足够的解释许多早期类型的星系,特别是复杂的和不同的恒星形成的历史所示的晕的质量非常不同的观察到的功能。在这幅图景中,先天似乎起着主导作用,而后天教育则是次要的。
The Relation Between Halo Shape, Velocity Dispersion and Formation Time
我们使用的暗物质晕确定的MareNostrum宇宙和星系群中确定的斯隆数据发布7星系目录,研究晕的形状和晕动力学之间的关系,参数化的系统的质量。一个强大的形状动力学,独立的质量,相关性是存在于模拟数据中,我们发现这是由于不同的晕形成时间。早期形成时间的晕,在目前的时代,更球形,并具有较高的速度比晚形成时间的晕的色散。晕圈形状-动力学相关性虽然较弱,但在2D投影中幸存下来(即,在投影形状和1-D速度分散之间)。一个类似的形状动力学的相关性,独立的质量,也被发现在SDSS DR 7星系群,为了调查其原因,我们已经测试和使用,作为一个代理的组形成时间,浓度参数。我们已经发现,在模拟晕的情况下,较低的浓度组,对应于形成时间晚,具有较低的速度分散和较高的伸长率比组具有较高的浓度值,对应于早期的形成时间。