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Xiaohu Yang (上海交通大学)6/19/23, 9:00 AMTalk
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Zhongxu Zhai (Shanghai Jiao Tong University)6/19/23, 9:10 AM
Nancy Grace Roman space telescope will conduct a High Latitude Spectroscopic Survey (HLSS) over 2000 square degrees at high redshift. I will introduce the flowdown of the Roman science objectives of galaxy and cosmology based on numerical simulations. With this reference model, we forecast the performance of the survey, including the galaxy type, number density, clustering property and...
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Qiao Wang (NAOC)6/19/23, 9:30 AM
介绍面向下一代大尺度巡天建立的4万亿粒子的数值模拟，以及在此基础上建立的数值模拟星表
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浩杰 许 (上海天文台)6/19/23, 9:50 AMTalk
We constrain cosmological parameters Ωm and σ8 from a joint analysis of galaxy clustering and galaxy-galaxy lensing from DESI Legacy Imaging Surveys Data Release 9 (DR9), covering approximately 10000 square degrees and spanning the redshift range of 0.1 to 0.9. In order to study the cosmological parameters dependence on redshift, we divide the galaxies into seven volume-limited lens samples,...
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Rui Guo6/19/23, 10:10 AM
To understand the formation of massive red spirals, we select optically red spirals with $M_{*}> 10^{10.5} M_{☉}$ based on the u-r color-stellar mass diagram from SDSS DR7 and compared the environment of these spirals with different NUV-r colors. All optically red galaxies have similar properties in the center, i.e., no star formation activity, similar bulge size, central velocity dispersion...
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Kwan Chuen Chan (Sun-Yat Sen University)6/19/23, 10:50 AM
We develop a new statistic, the projected three-dimensional correlation function, for the clustering analysis of the imaging galaxy survey data. This method can retain some of the radial information that is lost in conventional tomographic angular correlation analysis. As it is not strongly correlated with the angular correlation results, it can also provide important crosscheck. We have...
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Zhejie Ding (Shanghai Jiao Tong University)6/19/23, 11:10 AM
Dark Energy Spectroscopic Instrument (DESI) is the first on-going Stage IV spectroscopic redshift survey, covering a wide sky area and redshift range. As one of the key goals, DESI will measure the Baryon Acoustic Oscillations (BAO) from different tracers, including BGS, LRG, ELG and QSO at different redshifts. The density field reconstruction is significantly important to reduce the...
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Le Zhang (中山大学)6/19/23, 11:30 AM
In radio astronomy, reconstructing a sky map from time ordered data (TOD) is an inverse problem. Map-making techniques and gridding algorithms are commonly used, but they have limitations such as computational inefficiency, numerical instability, and an inability to remove beam effects. To address these issues, this study proposes a novel solution using the conditional invertible neural...
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Ms Zhaoxuan Zhang (Sun Yat-sen University)6/19/23, 11:50 AM
Time-ordered data (TOD) from ground-based CMB experiments is usually filtered before map-making to reduce the contamination from ground and atmospheric emissions. However, when the observation region contains strong point sources, the filtering process will cause a considerable leakage around the point sources, which should be eliminated to provide a clean CMB polarization map for scientific...
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Xun Shi6/19/23, 2:00 PM
Gravitational collapse of dark matter overdensities leads to the formation of dark matter haloes which embed galaxies and galaxy clusters. An intriguing feature of dark matter haloes is that their density profiles closely follow a universal form irrespective of the initial condition or the corresponding growth history. This represents a class of dynamical systems with emergent universalities....
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Jiaxin Han (Shanghai Jiao Tong University)6/19/23, 2:20 PM
I will talk about different boundaries of a dark matter halo focusing on our recently proposed depletion boundary. I will explain its physics and measurements, and illustrate how this new boundary could help us to gain new insights into halo evolution and to provide much improved description of the cosmic structure.
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义丰 周 (上海交通大学)6/19/23, 2:40 PM
We develop a self-consistent and accurate halo model by partitioning matter according to the depletion radii of haloes. Unlike conventional models that define haloes with the virial radius while relying on a separate exclusion radius or ad-hoc fixes to account for halo exclusion, our model distributes mass across all scales self-consistently. Using a cosmological simulation, we show that our...
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Prof. Go Ogiya (Zhejiang University)6/19/23, 3:00 PM
Recent observations revealed that the dark matter mass contained in two ultra diffuse galaxies in the vicinity of an elliptical galaxy, NGC 1052, is several hundred times lower than the predictions by the theoretical models of galaxy formation and evolution. The dynamics of the galaxies is described by only the gravity of stars. As such dark matter deficient galaxies can be a challenge for the...
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Zhaozhou Li6/19/23, 3:40 PMTalk
Recent observations reported a puzzling dearth of dark matter (DM) in a fraction of massive high-z galaxies and dwarf galaxies, challenging current simulation predictions within the standard LCDM scenario. This discrepancy underscores our limited understanding of the driving forces behind the halo structural evolution, including feedback outflows, mergers, and tidal interaction. Here we...
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Ms Yao Zhang (Tsinghua University)6/19/23, 4:00 PM
We propose a novel mechanism for constraining warm dark matter (WDM) models via the so-called “memory of reionization” effect, which is that gas in the intergalactic medium (IGM) after cosmic reionization can be affected significantly by inhomogeneous reionization of hydrogen. The suppression of small-scale structure due to WDM affects the evolution of post-reionization IGM, while thermal...
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飞鸿 何 (上海交通大学物理与天文学院天文系)6/19/23, 4:20 PM
The unified distribution model of cold dark matter (CDM) subhaloes is extended to the warm dark matter (WDM) case using a series of high-resolution N-body simulations with different WDM particle masses. The same model framework combining the unevolved mass function, unevolved radial distribution and tidal stripping can predict the mass function and spatial distribution of subhaloes in both CDM...
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Dr Wentao Luo (DSEL/USTC)6/19/23, 4:40 PM
We report the detection of a 282 $^{+34}_{-31}$ pc-sized dark matter core structure in the center of Milky Way at $68\%$ confidence level by using the micro-lensing event rate sky map data from the Optical Gravitational Lensing Experiment (OGLE) survey. For the first time, we apply the spacial information of the micro-lensing sky map and model it with the detailed Milky Way Dark Matter halo...
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Prof. 昱 容 (中国科学技术大学物理学院天文学系)6/20/23, 9:00 AM
观测以及Lambda冷暗物质模型框架下的标准星系演化模型都表明星系的恒星质量与其暗物质晕质量之间密切相关：红移0处，在Lstar星系（即质量约为5x10^11太阳质量）的暗物质晕中，恒星-暗物质晕质量比达到最高（~1%-5%）。然而，最近对星系团中超弥散星系UDG的研究表明近邻宇宙中可能存在一类维里质量与Lstar星系相当，但恒星-暗物质质量比极低的星系族群，这类特殊星系又被称为未发育完全的Lstar星系（FLG）。我们通过HI动力学的方法，首次寻找到了一批高置信度的FLG星系候选体，其有着极低的恒星质量（10^7-10^9太阳质量）、巨大的暗物质晕（>5x10^11太阳质量）、以及极低的恒星-暗物质质量比（<0.1%）。FLG星系的发现否定了修正牛顿动力学（MOND）理论。此外我们还发现50%的FLG候选者位于由星系团或星系群引力主导的区域，其热气体可能在早期宇宙中受到潮汐或冲压的...
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xianzhong zheng (Purple Mountain Observatory)6/20/23, 9:20 AM
We carried out a program to identify extremely overdense structures at z~2-3 and investigate connections between galaxy and structure formation. The two very massive structures at z=2.24 are mapped with Ha emission-line galaxies, SMGs and LAEs, and exhibit astonishing features unseen before. In this talk we introduce these finding about different galaxy populations in connections with the...
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Shuang Liu (Purple Mountain Observatory, CAS)6/20/23, 9:40 AM
Characterizing the structural properties of galaxies in high-redshift protoclusters is key to our understanding of the environmental effects on galaxy evolution in the early stages of galaxy and structure formation. We assess the structural properties of H$\alpha$ emission-line candidates (HAEs) in the densest regions of massive protoclusters at z=2-3, using HST $H$-band imaging data. Our...
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Ms 慧 洪 (中国科学技术大学)6/20/23, 10:00 AM
A stellar system is dynamically hot when its kinetic energy is dominated by random motion represented by the velocity dispersion $\sigma_{hot}$. We use MaNGA data to obtain inner and outer dispersion of a galaxy, $\sigma_{in}$ and $\sigma_{out}$, to characterize its dynamical status and study its connection with star-formation quenching and the growth of supermassive black hole(SMBH). We...
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鑫 王6/20/23, 10:40 AM
Using state-of-the-art analysis methods, we reduce the new NIRISS wide-field grism data and NIRSpec multi-object spectroscopic (MOS) data. The cross calibration of two complementary spectroscopic modes opens up new key window on unbiased investigation of star formation, feedback, and ISM properties in and beyond the cosmic noon epoch. We bring forth the first spatially resolved analysis of...
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文祥 裴 (国家天文台)6/20/23, 11:00 AM
In anticipation of the upcoming deployment of the Chinese Space Station Telescope (CSST), we present galaxy catalog by the well-established LGalaxies semi-analytic model and galaxy emission line catalog by post-processing. We have made modifications to the models to solve the time convergence problem and re-calibrated the parameters to accurately reproduce the observed black hole mass function...
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Mr 世银 沈 (上海天文台)6/20/23, 11:20 AM
We present a new two-component dust geometry model of disk galaxies, the Chocolate Chip Cookie (CCC) model, where the clumpy nebular regions are embedded in a diffuse stellar/interstellar medium disk, like chocolate chips in a cookie. Our model solves the dust attenuation process for both the emission lines and stellar continua via analytical approaches, which successfully fits the inclination...
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Enci Wang (USTC)6/20/23, 11:40 AM
I will talk about the formation of exponential star-forming disk and the corresponding metal enrichment in the modified accretion disk (MAD) framework. The MAD is suggested by the recent simulations that coplanar gas inflow mainly provides the fuel of star formation. We treat the galactic gas disk as a simple gas-regulator system that the SFR is instantaneously determined by the gas content,...
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Yipeng Jing6/21/23, 9:00 AM
In ongoing and future cosmological surveys, such as DESI, PFS, Euclid, CSST, and WFIRST, ELGs are a critically major tracer to explore the acceleration of the cosmic expansion and to test modified gravity theories. To achieve the high-precision observations aimed by the surveys on the Hubble parameter, cosmic growth rate and neutrino mass etc, one needs to have an accurate understanding of...
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shanquan gui (Shanghai JiaoTong University)6/21/23, 9:25 AM
The Photometric objects Around Cosmic webs (PAC) approach developed in \cite{2022ApJ...925...31X} has the advantage of making full use of the spectroscopic and deeper photometric surveys. With the merits of PAC, we can accurately measure quasars-galaxy cross-correlations at small scale down to $0.1\,h^{-1}{\rm{Mpc}}$ and at different stellar mass bins. We calculate the excess surface density...
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佳程 孟 (清华大学天文系)6/21/23, 9:45 AM
This work consists of two parts. The first is the study of the galaxy population in the SDSS galaxy groups with DESI imaging data. The second is the study on how to measure galaxy abundance and clustering at high redshift from incomplete spectroscopic data.
In the first part, we use the most recent data release (DR9) of the DESI legacy imaging survey and SDSS galaxy groups to measure the...
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青 谷 (国家天文台)6/21/23, 10:30 AM
In the framework of the standard cosmological model, dark matter halos grow by hierarchical clumping. The spatial distribution of satellite galaxies is closely related to the nature of the halo and its accretion history. Firstly, using SDSS and Millennium simulations we study the spatial distribution of satellites in galaxy clusters. We find that the distribution of satellite galaxies is...
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艳蕊 周6/21/23, 10:50 AM
Motivated by previous findings that the magnitude gap between certain satellite galaxies and the central galaxy can be used to improve the estimation of halo mass, we carry out a systematic study of the information content of different member galaxies in the modeling of the host halo mass using a machine-learning approach. We employ data from the hydrodynamical simulation IllustrisTNG and...
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Yirong Wang (上海交通大学)6/21/23, 11:10 AM
In this investigation, we leverage the combination of DESI legacy imaging surveys DR9, survey vilification (sv3), and year 1 (Y1) spectroscopic redshift data to estimate the conditional luminosity and stellar mass functions (CLFs & CSMFs) of galaxies across various halo mass bins and redshift ranges, with the help of a realistic DESI mock galaxy redshift survey (MGRS) generated from a...
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Yangyao Chen6/21/23, 11:30 AM
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Prof. Houjun Mo (U. Mass.)6/22/23, 9:00 AM
I will present a review on how to use targets provided by galaxies, galaxy groups and reconstructed density field to study the cosmic web, galaxy formation and evolution.
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Xiaoju Xu (上海交通大学)6/22/23, 9:25 AM
Machine learning techniques are widely implemented to predict galaxy properties based on halo or subhalo properties in semi-analytic models (SAM) and hydrodynamic simulations. The multivariate relation between galaxy and halo or subhalo can be captured and reproduced efficiently. However, the galaxy formation and evolution in galaxy formation models may deviate from those in the real Universe,...
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Renjie Li6/22/23, 9:45 AM
Using reconstructed initial conditions in the Sloan Digital Sky Survey (SDSS) survey volume, we carry out constrained hydrodynamic simulations in three regions representing different types of the cosmic web: the Coma cluster of galaxies; the SDSS Great Wall; and a large low-density region at z ∼ 0.05. The simulations successfully predict some discontinuities associated with shock fronts and...
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Yin Li6/22/23, 10:05 AM
Rapid advances in deep learning have brought not only myriad powerful neural networks, but also breakthroughs that benefit established scientific research. In particular, automatic differentiation (AD) tools and computational accelerators like GPUs have facilitated forward modeling of the Universe with differentiable simulations. Current differentiable cosmological simulations are limited by...
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霄栋 李 (中山大学)6/22/23, 10:45 AM
I will discuss our work on the reconstruction of the cosmic velocity field from the redshift-space distribution of dark matter halos using the state-of-the-art deep learning technique. We were able to accurately recover the magnitude, divergence and vorticity of the velocity field, with the power spectra recovered at 80% accuracy at $k < 1.1\ h$/Mpc. This approach is very promising and...
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Feng Shi (Xidian University)6/22/23, 11:05 AM
We develop a deep learning technique to reconstruct the dark matter density field from the redshift-space distribution of dark matter halos. We implement a UNet-architecture neural network and successfully trained it using the COLA fast simulation, which is an approximation of the N-body simulation with $512^3$ particles in a box size of $500 \mpch$. We evaluate the resulting UNet model not...
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Qiufan Lin (Pengcheng Lab)6/22/23, 11:25 AM
Obtaining well-calibrated probability density functions (PDFs) of photometric redshift (photo-z) for galaxies without using spectroscopy remains a challenge for many science goals. Deep learning tools have proven to be powerful for this task and gained growing popularity. These include, in particular, state-of-the-art deep neural networks that are typically fed with multi-band galaxy images or...
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Kai Wang6/22/23, 11:45 AM
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萌 周 (清华大学)6/23/23, 9:00 AM
我们介绍一种新的模拟宇宙再电离和加热过程的半数值方法 SIRIUS (Simulation of IGM Reionization In the Universe with Shell-wise method)。国际流行的半数值模拟软件21cmFAST是基于excursion set model of reionization，在大尺度上有一定局限性。SIRIUS对标21cmFAST，但采用了完全不同的近似方案：利用一维辐射转移近似模拟紫外光子的辐射转移，并利用球壳窗口函数进行数值加速；同时，采用线性微扰再电离模型模拟X射线光子的辐射转移和加热效应。我们的新方法在单光源测试中获得与解析解一致的结果，并在宇宙学物质场的再电离测试中获得有效的结果。
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Dr 坚 富 (shanghai astronomical observatory)6/23/23, 9:20 AM
The gas components play very important role in the baryon cycles and evolution processes in galaxy formation. In this talk, we present our recent work on simulating the observations of HI gas in ISM and hot ionized gas in CGM and ICM.
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For the cold gas, we generate the mock observation of the 21cm interferometer signals by radio arrays for HI gas in galaxies. We developed a software OmniUV,... -
Mr 文心 钟 (中国科学院上海天文台)6/23/23, 9:40 AM
Hot ionized gas is important in the baryon cycle of galaxies and may contribute the majority of their “missing baryons”. Up till now, most semi-analytic models of galaxy formation have paid little attention to the hot gaseous haloes and their X-ray emission. In this paper, we adopt the one-dimensional model from Sharma et al. instead of the isothermal sphere in L-Galaxies...
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一纬 张 (云南大学中国西南天文研究所)6/23/23, 10:00 AM
Recently, the high metallicity in the outskirts of galaxy clusters has been puzzling and asks for a deeper investigation of the transport mechanisms in the intracluster medium (ICM). We studied the transport mechanisms in the ICM using tracer particle re-simulation of the Omega500 cosmological hydrosimulation, and focused on the particle transport during major mergers. We used pair dispersion...
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Lizhi Xie (Tianjin Normal University)6/23/23, 10:40 AM
Gas is the essential component in a galaxy that dominates its evolution. It also provides insight into the large-scale structure and the evolution of the Universe. In this talk, I will introduce an overview of treatments of gas and star formation in our updated semi-analytic model. Our model includes a self-consistent partition of HI and H$_2$ in the cold gas disk, as well as environmental...
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Hong Guo (Shanghai Astronomical Observatory)6/23/23, 11:00 AM
Accurately modeling the cold gas content in the universe is challenging for current theoretical models. We propose a new empirical model NeutralUniverseMachine to describe the evolution of HI and H2 gas along with the dark matter halos based on the UniverseMachine catalog. It is able to accurately fit the observed HI and H2 mass functions, molecular-to-atomic ratio, HI-halo mass relation,...
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Zhixing Li6/23/23, 11:20 AM
Atomic hydrogen (HI) gas, mostly residing in dark matter halos after cosmic reionization, is the fuel for star formation. Its relation with properties of host halo is the key to understand the cosmic HI distribution. In this work, we propose a flexible, empirical model of HI-halo relation. In this model, while the HI mass depends primarily on the mass of host halo, there is also secondary...
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Xiao Li (Tsinghua University)6/23/23, 11:40 AM
We present a new H I mass estimator that relates log10(MHI/M*) to a linear combination of four galaxy properties: stellar surface mass density, color index u − r, stellar mass, and concentration index, with the scatter of individual galaxies around the mean H I mass modeled with a Gaussian distribution function. We calibrate the estimator using the xGASS sample, including both H I detection...
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Yirong Wang (上海交通大学)HaloPoster
In this investigation, we leverage the combination of DESI legacy imaging surveys DR9, survey vilification (sv3), and year 1 (Y1) spectroscopic redshift data to estimate the conditional luminosity and stellar mass functions (CLFs & CSMFs) of galaxies across various halo mass bins and redshift ranges, with the help of a realistic DESI mock galaxy redshift survey (MGRS) generated from a...
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Li Ran
CSST is a 2m space-based telescope, designed to work in Low Earth Orbit for 10 years from ~2024. It will image 17,500 square degrees in six near-UV and optical bands (u,g,r,i,z,y) to an average depth of 25.5 AB (5-sigma point source) and a combined depth of 26 AB (5-sigma point source), with the angular resolution R80 = 0.15", providing a unique and promising platform to study the structure of...
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Caina Hao
It is well-known that there is a correlation between the galaxy color/quiescence and the morphology. Especially, the more recent studies revealed a tight correlation between the central stellar mass surface density within 1 kpc and the total stellar mass for quiescent galaxies, which suggests that a dense core is an indicator for quenching. Therefore, the population of blue star-forming spiral...
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