The red sequence at birth in the galaxy cluster ClJ1449+0856 at z=2
V. Strazzullo, E. Daddi, R. Gobat, F. Valentino, M. Pannella, M. Dickinson, A. Renzini, G. Brammer, M. Onodera, A. Finoguenov, A. Cimatti, C. M. Carollo, N. Arimoto
We use HST/WFC3 imaging to study the red population in the IR-selected, X-ray detected, low-mass cluster Cl J1449+0856 at z=2, one of the few bona-fide established clusters discovered at this redshift, and likely a typical progenitor of an average massive cluster today. This study explores the presence and significance of an early red sequence in the core of this structure, investigating the nature of red sequence galaxies, highlighting environmental effects on cluster galaxy populations at high redshift, and at the same time underlining similarities and differences with other distant dense environments. Our results suggest that the red population in the core of Cl J1449+0856 is made of a mixture of quiescent and dusty star-forming galaxies, with a seedling of the future red sequence already growing in the very central cluster region, and already characterising the inner cluster core with respect to lower density environments. On the other hand, the color-magnitude diagram of this cluster is definitely different from that of lower-redshift (z<1) clusters, as well as of some rare particularly evolved massive clusters at similar redshift, and it is suggestive of a transition phase between active star formation and passive evolution occurring in the proto-cluster and established lower-redshift cluster regimes.
This work presents the first comprehensive study of structure formation at the peak epoch of cosmic star formation over $1.4\leq z \leq 3.6$ in the COSMOS field, including the most massive high redshift galaxy proto-clusters at that era. We apply the extended COSMIC BIRTH algorithm to account for a multi-tracer and multi-survey Bayesian analysis at Lagrangian initial cosmic times. Combining the data of five different spectroscopic redshift surveys (zCOSMOS-deep, VUDS, MOSDEF, ZFIRE, and FMOS-COSMOS), we show that the corresponding unbiased primordial density fields can be inferred, if a proper…
Exploring the Sun's birth radius and the distribution of planet building blocks in the Milky Way galaxy: A multi-zone Galactic chemical evolution approach
High-Mass X-ray Binaries (HMXBs) are produced after the first supernova event in a massive binary. These objects are intrinsically young, and can suffer from a significant natal kick. As such, the progenitors of HMXBs are likely to have formed away from the current location of the X-ray emitting systems. We aim to find the birthplace of the known HMXBs of our Milky Way. Specifically, we want to answer the question whether the formation of HMXBs can be associated to open stellar clusters and/or Galactic spiral structures, and infer from that the time elapsed since the first supernova event. We …
The birth of the Milky Way as uncovered by accurate stellar ages with Gaia
了解星系一生中形成的恒星的年龄是了解其形成和演化的基础。然而，恒星年龄很难获得，因为它们无法通过观测来测量，需要与恒星模型（Soderblom 2010）进行比较。另外，年龄分布可以通过颜色-星等图拟合（Gallart et al. 2005）得到，到目前为止主要用于研究附近的星系。从盖亚任务到个别银河系恒星的新距离（Brown et al. 2018）使我们能够使用这种技术从厚盘色星等图和运动学热局部晕的神秘的双序列色星等图中推导出年龄（Babusiaux et al. 2018），其中蓝色序列与重大吸积事件有关（Haywood et al. 2018，Helmi et al. 2018）。由于缺乏准确的年龄，合并的时间及其对银河系早期演化的作用仍然不清楚。我们发现，在这两个晕序列中的恒星具有相同的年龄分布，并且比大部分厚盘星更老。10 Gyr前切割的尖锐晕年龄可以与盖亚-土卫二的吸积相确定。随着星系形成的最先进的宇宙学模拟（布鲁克等人，2012），这些强大的年龄使我们能够对塑造我们银河系的早期事件序列进行排序，确定红色序列是银河系祖先中形成的第一批恒星，由于其运动学，可以被描述为长期寻找的原位晕。
The [α/Fe]-[Fe/H] relation in the E-MOSAICS simulations: its connection to the birth place of globular clusters and the fraction of globular cluster field stars in the bulge
(Abridged) In this paper, we use the Tuffs et al. attenuation - inclination models in ultraviolet (UV), optical, and near-infrared (NIR) bands to investigate the average global dust properties in galaxies as a function of stellar mass $M_{*}$, stellar mass surface density $μ_{*}$, star-formation rate $SFR$, specific star-formation rate $sSFR$, star-formation main-sequence offset $dMS$, and star-formation rate surface density $Σ_{SFR}$ at redshifts $z \sim 0$ and $z \sim 0.7$. We use star-forming galaxies from SDSS ($\sim$ 20000) and GAMA ($\sim$ 2000) to form our low-z sample at $0.04 < z < 0.…
Recent work has demonstrated that exoplanetary system properties correlate strongly with ambient stellar clustering in six-dimensional stellar position-velocity phase space, quantified by dividing planetary systems into sub-samples with high or low phase space densities (`overdensity' and `field' systems, respectively). We investigate the physical origins of the phase space overdensities and, thereby, which environmental mechanisms may have impacted the planetary systems. We consider the galactic-scale kinematic structure of the Milky Way observed with Gaia and show that the overdensities corr…
We have used Hubble Space Telescope (HST) images, SAURON Integral Field Spectroscopy (IFS) and adaptative optics assisted Gemini NIFS near-infrared K-band IFS to map the stellar and gas distribution, excitation and kinematics of the inner few kpc of the nearby edge-on S0 galaxy NGC 4111. The HST images map its $\approx$ 450 pc diameter dusty polar ring, with an estimated gas mass $\ge10^7$ M$_\odot$. The NIFS datacube maps the inner 110 pc radius at $\approx$ 7 pc spatial resolution revealing a $\approx$ 220 pc diameter polar ring in hot ($2267\pm166$ K) molecular H$_2$ 1-0 S(1) gas embedded i…
The chemodynamical memory of a major merger in a NIHAO-UHD Milky Way analogue -- I. A golden thread through time and space
Australian National University（澳大利亚国立大学）；Universität Heidelberg（海德堡大学）；Universitá degli Studi di Firenze（佛罗伦萨大学）；The Observatories of the Carnegie Institution for Science（卡内基科学研究所天文台）；Northwestern University（西北大学）；New Mexico State University（新墨西哥州立大学）；University of Cambridge（剑桥大学）
The physical properties of galaxies are encoded within their spectral energy distribution and require comparison with models to be extracted. These models must contain a synthetic stellar population and, where infrared data is to be used, also consider prescriptions for energy reprocessing and re-emission by dust. While many such models have been constructed, there are few analyses of the impact of stellar population model choice on derived dust parameters, or vice versa. Here we apply a simple framework to compare the impact of these choices, combining three commonly-used stellar population s…
Surface abundances of C, N, and O in red giants are affected by processed material mixed into the stars' convective envelopes. Using a sample of $\sim 5100$ stars with elemental abundances from APOGEE and asteroseismic masses from {\it Kepler}, we test theoretical stellar models that predict this mixing, then apply these models to derive birth C, N, and O abundances for these stars. Our models with standard mixing can reproduce the observed trends to within plausible uncertainties in the birth abundances. Some models with ''extra'' mixing processes fail, predicting trends with surface gravity …
