[Abridged] In this paper we derive the central stellar mass density within a fixed radius and the effective stellar mass density within the effective radius for a complete sample of 34 ETGs morphologically selected at 0.9<z_{spec}<2 and compare them with those derived for a sample of ~900 local ETGs in the same mass range. We find that the central stellar mass density of high-z ETGs spans just an order of magnitude and it is similar to the one of local ETGs as actually found in previous studies.However, we find that the effective stellar mass density of high-z ETGs spans three orders of magnitude, exactly as the local ETGs and that it is similar to the effective stellar mass density of local ETGs showing that it has not changed since z~1.5, in the last 9-10 Gyr. Thus, the wide spread of the effective stellar mass density observed up to z~1.5 must originate earlier, at z>2. Also, we show that the small scatter of the central mass density of ETGs compared to the large scatter of the effective mass density is simply a peculiar feature of the Sersic profile hence, independent of redshift and of any assembly history experienced by galaxies. Thus, it has no connection with the possible inside-out growth of ETGs. Finally, we find a tight correlation between the central stellar mass density and the total stellar mass of ETGs in the sense that the central mass density increases with mass as M^{~0.6}. This implies that the fraction of the central stellar mass of ETGs decreases with the mass of the galaxy. These correlations are valid for the whole population of ETGs considered independently of their redshift suggesting that they originate in the early-phases of their formation.
New observational Constraints on the Growth of the First Supermassive Black Holes
我们限制总吸积质量密度在z>6的超大质量黑洞,推断通过从光度选择的星系候选者的样本的集成X射线发射的上限。研究从最深的哈勃太空望远镜图像中获得的星系,结合钱德拉深场南的钱德拉4兆秒观测,我们获得了早期宇宙中总黑洞生长的最严格限制。我们估计在z~6处的吸积质量密度<1000 Mo Mpc^-3,明显低于先前根据早期黑洞增长的一些现有模型和早期观测所作的预测。这些结果对早期黑洞的增长和通过吸积的质量聚集提出了有趣的限制,并暗示了以下一个或多个问题:(1)在这个时期,只有一小部分明亮的星系含有活跃的黑洞;(2)早期大多数黑洞的增长发生在尘埃和/或质量较小的--尚未被探测到的--宿主星系中;(3)在星系样本中有相当大比例的低z闯入者;(4)早期黑洞的增长是辐射效率低的,严重模糊和/或由于黑洞合并而不是吸积;或(5)大部分黑洞增长发生在晚期。所有这些可能性对我们理解高红移种子形成模型具有重要意义。
Growth, geometry, and early-universe split of the matter density parameter $Ω_{\rm m}$
Univ Toulouse(图卢兹大学);CNES(法国国家空间研究中心);CNRS(法国国家科学研究中心);IRAP(天体物理与行星科学研究所);Institute of Space Sciences (ICE, CSIC)(空间科学研究所(ICE, CSIC));Institut d’Estudis Espacials de Catalunya (IEEC)(加泰罗尼亚空间研究所)
In this work, we use the constrained Gaussian realization technique to study the early growth of supermassive black holes (SMBHs) in cosmological hydrodynamic simulations, exploring its relationship with features of the initial density peaks on large scales, ~1 Mpc/h. Our constrained simulations of volume (20 Mpc/h)^3 successfully reconstruct the large-scale structure as well as the black hole growth for the hosts of the rare 10^9 Msun SMBHs found in the BlueTides simulation at z~7. We run a set of simulations with constrained initial conditions by imposing a 5 σ_0(R_G) peak on scale of R_G = …
The evolution of the mass-size relation for early type galaxies from z~1 to the present: dependence on environment, mass-range and detailed morphology
选取了从z~1到现在的298个星系群和384个观测场的静止早型星系样本,研究了星系大小演化对形态、恒星质量和大尺度环境的依赖性。星系大小的增长取决于星系质量和早期星系形态,例如,椭圆星系的演化方式与透镜星系不同。在低质量端- $10.5<Log(M/M_\odot)<11$,椭圆体从$z\sim1$到现在没有显示出强烈的尺寸增长(10%到30%,取决于形态分类)。另一方面,大质量椭圆星系log(M/M_ \odot)>11.2 $- approximately doubled their size. Interestingly, lenticular galaxies display different behavior: they appear more compact on average and they do show a size growth of \sim60% since z=1 independent of stellar mass. We compare our results with state-of-the art semi-analytic models. While major and minor mergers can account for most of the galaxy size growth, we find that with pres…
It is not well understood whether the growth of early-type cluster galaxies proceeds inside-out, outside-in, or at the same pace at all radii. In this work we measured the galaxy size, defined by the radius including 80\% of the galaxy light, non-parametrically. We also determined a non-parametric estimate of galaxy light concentration, which measures the curvature of the surface brightness profile in the galaxy outskirts. We used an almost random sampling of a mass-limited sample formed by 128 morphologically early-type galaxies in clusters with $\log M/M_{\odot} \ga 10.7$ spanning the wide r…
We present a scenario for fast growth of cosmological perturbations; $δ(t) \sim a(t)^s$, $a(t)$ being the scale factor, with $s > 10$ for the numerical examples reported in this article. The basic ingredients of the scenario are an early matter dominated era and the dark fermion which experiences a scalar mediated force during the epoch. Both of these arise in string/supergravity models. The fast growth occurs for sub-horizon density perturbations of the dark fermion. The fast growth has a rich set of phenomenological implications. We outline implications for the formation of primordial black …
We explore the effect of dust on the growth of seed black holes (BHs) in the early universe. Previous 1D radiation-hydrodynamic (RHD) simulations show that increased radiation pressure on dust further suppresses the accretion rate than the case for the chemically pristine gas. Using the Enzo+Moray code, we perform a suite of 3D RHD simulations of accreting BHs in a dusty interstellar medium (ISM). We use the modified Grackle cooling library to consider dust physics in its non-equilibrium chemistry. The BH goes through an early evolutionary phase, where ionizing BH radiation creates an oscillat…
The central dark-matter fraction of galaxies is sensitive to feedback processes during galaxy formation. Strong gravitational lensing has been effective in the precise measurement of the dark-matter fraction inside massive early-type galaxies. Here, we compare the projected dark-matter fraction of early-type galaxies inferred from the SLACS strong-lens survey, with those obtained from the EAGLE, Illustris, and IllustrisTNG hydro-dynamical simulations. Previous comparisons with some simulations revealed a large discrepancy, with considerably higher inferred dark-matter fractions -- by factors 2…
Early growth of massive black holes in dynamical dark energy models with negative cosmological constant
Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Roma(意大利国家天体物理研究所罗马天文台);Centre for Theoretical Physics, Jamia Millia Islamia(贾米阿米利娅大学理论物理中心);School of Physics & Astronomy, University of Southampton(南安普顿大学物理与天文学院)