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Modeling the Covariance Matrix for the Power Spectra Before and After the BAO Reconstruction

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Research in Astronomy and Astrophysics 2024年第12期24卷 158-176页

作者： Ruiyang zhao Kazuya Koyama Yuting Wang gong-bo zhao National Astronomical Observatories Chinese Academy of Sciences School of Astronomy and Space Science University of Chinese Academy of Sciences Institute of Cosmology & Gravitation University of Portsmouth Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Chinese Academy of Sciences South America Center for Astronomy (CASSACA) National Astronomical Observatories of China

The baryon acoustic oscillations （BAO） reconstruction plays a crucial role in cosmological analysis for spectroscopic galaxy surveys because it can make the density field effectively more linear and more *** combination of the power spectra before and after the BAO reconstruction helps break degeneracies among parameters,then improves the constraints on cosmological *** is therefore important to estimate the covariance matrix between pre-and post-reconstructed power *** this work,we use perturbation theory to estimate the covariance matrix of the related power spectra multipoles,and check the accuracy of the derived covariance model using a large suite of dark matter halo catalogs at z=*** find that the diagonal part of the auto covariance is well described by the Gaussian prediction,while the cross covariance deviates from the Gaussian prediction quickly when k>0.1 h ***,we find the non-Gaussian effect in the nondiagonal part of the cross covariance is comparable to,or even stronger than,the pre-reconstruction *** adding the non-Gaussian contribution,we obtain good agreement between analytical and numerical covariance matrices in the non-diagonal part up to k;0.15 h *** agreement in the diagonal part is also improved,bu still under-predicts the correlation in the cross covariance block.

关键词： (cosmology:) cosmological parameters (cosmology:) large-scale structure of universe cosmology: theory

Dynamical Dark Energy in Light of Cosmic Distance Measurements.Ⅰ.A Demonstration Using Simulated Datasets

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Research in Astronomy and Astrophysics 2024年第6期24卷 7-14页

作者： Gan Gu Xiaoma Wang Xiaoyong Mu Shuo Yuan gong-bo zhao National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China

We develop methods to extract key dark energy information from cosmic distance measurements including the BAO scales and supernova(SN) luminosity *** using simulated data sets of the complete DESI,LSST and Roman surveys designed for BAO and SN distance measurements,we show that using our method,the dynamical behavior of the energy,pressure,equation of state(with its time derivative) of dark energy and the cosmic deceleration function can all be accurately recovered from high-quality data,which allows for robust diagnostic tests for dark energy models.

关键词： (cosmology:)dark energy (cosmology:)large scale structure of universe (cosmology:)cosmic background radiation (cosmology:)cosmological parameters

Dynamical Dark Energy in Light of Cosmic Distance Measurements.Ⅱ.A Study Using Current Observations

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Research in Astronomy and Astrophysics 2024年第6期24卷 15-20页

作者： Xiaoma Wang Gan Gu Xiaoyong Mu Shuo Yuan gong-bo zhao National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China

We extract key information on dark energy from current observations of BAO,OHD and H_(0),and find hints of dynamical behavior of dark *** particular,a dynamical dark energy model whose equation of state crosses-1 is f... 详细信息

关键词： Cosmology (cosmology:)dark energy cosmology:observations

A New Consistency Test forΛCDM Cosmology Using Galaxy Surveys

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Research in Astronomy and Astrophysics 2022年第6期22卷 183-189页

作者： Jinglan Zheng gong-bo zhao Yuting Wang Xiaoyong Mu Ruiyang zhao Weibing Zhang Shuo Yuan David Bacon Kazuya Koyama National Astronomy Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China Institute of Cosmology and Gravitation University of PortsmouthDennis Sciama BuildingPortsmouth PO13FXUK

We propose a new consistency test for theΛCDM cosmology using baryonic acoustic oscillations(BAO)and redshift space distortion(RSD)measurements from galaxy redshift ***,we determine the peak position of fσ8(z)in redshift z offered by an RSD measurement,and compare it to the one predicted by the BAO observables assuming a flatΛCDM *** demonstrate this new test using the simulated data for the DESI galaxy survey,and argue that this test complements those using the background observables alone,and is less subject to systematics in the RSD analysis,compared to traditional methods using values of fσ8(z)directly.

关键词： Cosmology-(cosmology:)dark energy-galaxies distances and redshifts

Reconstructing the temporal evolution of the speed of light in a flat FRW Universe

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Research in Astronomy and Astrophysics 2019年第10期19卷 138-144页

作者： Dan-Dan Wang Han-Yu Zhang Jing-Lan Zheng Yu-Ting Wang gong-bo zhao National Astronomical Observatories Chinese Academy of Sciences Beijing 100101 China University of Chinese Academy of Sciences Beijing 100049 China Department of Physics Kansas State University116 Cardwell HallManhattanKS 66506USA School of Astronomy and Space Science University of Chinese Academy of Sciences Beijing 100049 China Institute of Cosmology and Gravitation University of Portsmouth Portsmouth POl 3FX UK

We present a novel method to reconstruct the temporal evolution of the speed of light c(z) in a flat Friedmann-Robertson-Walker(FRW) Universe using astronomical observations. After validating our pipeline with mock datasets, we apply our method to the latest baryon acoustic oscillations(BAO) and supernovae observations, and reconstruct c(z) in the redshift range of z ∈[0, 1.5]. We find no evidence of a varying speed of light, although we see some interesting features of △c(z), the fractional difference between c(z) and c0(the speed of light in the International System of Units), e.g.,△c(z) 0 at 0.2≤z≤0.5 and 0.8≤z≤1.3, respectively, although the significance of these features is currently far below statistical importance.

关键词： cosmology-dark energy-large scale structure

Probing dynamics of dark energy with latest observations

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Research in Astronomy and Astrophysics 2017年第6期17卷 5-10页

作者： Yue-Cheng Zhang Han-Yu Zhang Dan-Dan Wang Yang-Han Qi Yu-Ting Wang gong-bo zhao National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China University of Chinese Academy of Sciences Beijing 100049 China Department of Physics & Astronomy Swarthmore College Swarthmore PA 19081 USA Institute of Cosmology and Gravitation University of Portsmouth Portsmouth PO1 3FX UK

We examine the validity of the ACDM model and probe the dynamics of dark energy with the latest astronomical observations. Using the Ore（z） diagnosis, we find that various kinds of observational data are in tension within the ACDM framework. We then allow for dynamics of dark energy and investigate the constraint on dark energy parameters. We find that for two different kinds of parametri- sations of the equation of state parameter w, a combination of current data mildly favours an evolving w, although the significance is not sufficient for it to be supported by Bayesian evidence. A forecast of the DESI survey shows that the dynamics of dark energy could be detected at the 7σ confidence level and would be decisively supported by Bayesian evidence, if the best-fit model of w derived from current data is the true model.

关键词： cosmology - dark energy - large scale structure

Probing primordial gravitational waves: Ali CMB Polarization Telescope

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National Science Review 2019年第1期6卷 145-154页

作者： Hong Li Si-Yu Li Yang Liu Yong-Ping Li Yifu Cai Mingzhe Li gong-bo zhao Cong-Zhan Liu Zheng-Wei Li He Xu Di Wu Yong-Jie Zhang Zu-Hui Fan Yong-Qiang Yao Chao-Lin Kuo Fang-Jun Lu Xinmin Zhang Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Theoretical Physics Division Institute of High Energy PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences CAS Key Laboratory for Researches in Galaxies and Cosmology Department of AstronomyUniversity of Scienceand Technology of China Interdisciplinary Center for Theoretical Study University of Science and Technology of China National Astronomical Observatories Chinese Academy of Sciences Institute of Cosmology& Gravitation University of Portsmouth Key Laboratory of Particle Astrophysics Institute of High EnergyPhysics Chinese Academy of Sciences Key Laboratory of Particle Astrophysics Institute of High Energy Physics ChineseAcademy of Sciences Department of Astronomy School of Physics Peking University Physics Department Stanford University

In this paper, we will give a general introduction to the Ali CMB Polarization Telescope(Ali CPT) project,which is a Sino–US joint project led by the Institute of High Energy Physics and involves many different institutes in China. It is the first ground-based Cosmic Microwave Background(CMB) polarization experiment in China and an integral part of China’s Gravitational-wave Program. The main scientific goal of the Ali CPT project is to probe the primordial gravitational waves(PGWs) originating from the very early Universe. The AliCPT project includes two stages. The first stage, referred to as AliCPT-1, is to build a telescope in the Ali region of Tibet at an altitude of 5250 meters. Once completed, it will be the highest ground-based CMB observatory in the world and will open a new window for probing PGWs in the northern hemisphere. The AliCPT-1 telescope is designed to have about 7000 transition-edge sensor detectors at 95 GHz and 150 GHz. The second stage is to have a more sensitive telescope(Ali CPT-2) with more than 20 000 detectors. Our simulations show that AliCPT will improve the current constraint on the tensor-to-scalar ratio r by one order of magnitude with three years’ observation. Besides the PGWs, Ali CPT will also enable a precise measurement of the CMB rotation angle and provide a precise test of the CPT symmetry. We show that three years’ observation will improve the current limit by two orders of magnitude.

关键词： primordial gravitational waves cosmic microwave background Ali CMB Polarization Telescope

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一种测定HPAM水解度的新方法

高分子材料科学与工程 2006年第2期22卷 194-196页

作者：娄清香宫兆波陈权生勘探开发研究院新疆克拉玛依834000

提出了一种通过阴离子聚合物与阳离子聚合物间相互作用来测定部分水解聚丙烯酰胺（HPAM）水解度的新方法，可以避免由于滴定法终点判断不准对水解度检测造成的误差，所得到的标准曲线线性回归相关系数达到了0．9972，该方法尤其适用于... 详细信息

提出了一种通过阴离子聚合物与阳离子聚合物间相互作用来测定部分水解聚丙烯酰胺（HPAM）水解度的新方法，可以避免由于滴定法终点判断不准对水解度检测造成的误差，所得到的标准曲线线性回归相关系数达到了0．9972，该方法尤其适用于水解度在10％～30％范围内的HPAM产品水解度的测定．对HPAM工业产品由该方法所测得的水解度值与GB 12005．6—89提供的方法测得的水解度值相对误差为1．3％。

关键词：阴离子聚合物阳离子聚合物相互作用 HPAM 水解度测定方法

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重涂底漆苯丙乳液的制备

中国涂料 2018年第2期33卷 25-29页

作者：唐兵龚博文赵凯佛山市顺德区巴德富实业有限公司广东佛山528322

普通底漆针对粉化老旧墙体,往往只能铲掉重涂,因为其渗透加固性能达不到要求。通过环氧改性,辅助特殊表面活性剂提高渗透加固和高抗碱性,达到旧墙体翻新重涂底漆的要求;分析了环氧树脂种类和用量,乳化剂种类和用量,引发剂用量和酸的种... 详细信息

普通底漆针对粉化老旧墙体,往往只能铲掉重涂,因为其渗透加固性能达不到要求。通过环氧改性,辅助特殊表面活性剂提高渗透加固和高抗碱性,达到旧墙体翻新重涂底漆的要求;分析了环氧树脂种类和用量,乳化剂种类和用量,引发剂用量和酸的种类对底漆性能的影响。实验结果得出,采用占单体量8%环氧树脂E44,辅助占单体总量3%的磷酸酯类表面活性剂和含氟表面活性剂(比例2∶1),用0.9%的引发剂,在丙烯酸体系下合成可以达到非常好的渗透加固和抗泛碱性能。

关键词：苯丙乳液环氧树脂底漆乳液合成影响因素