宇宙学是研究宇宙起源、演化及结构的科学。随着天文观测的快速发展和理论研究的深入展开，我们对宇宙的认知发生了革命性的改变，同时面临新的挑战。探索暗物质、暗能量和引力性质已成为21世纪重大科学问题。星系、星系团是宇宙大尺度结构的重要示踪体，深入理解其形成与演化具有重要意义。针对这些前沿科学问题，本团组结合多种探针开展宇宙学研究。

Cosmology is a branch of science aiming to probe the origin and evolution of the Universe and the structures therein. The tremendous developments, both observational and theoretical, in the past decades have revolutionized our understandings about the cosmos. Meanwhile, new challenges have emerged. What is the nature of dark matter and dark energy? Is General Relativity still the governing theory on cosmological scales? These are the fundamental questions to be answered in the 21st century. Galaxies and clusters of galaxies are observable tracers of large-scale structures in the Universe. Understanding their formation and evolution is essentially important in astrophysical and cosmological studies. Targeting at answering these fundamental questions, our studies employ multiple probes and tracers for cosmological analyses.

在引力透镜、微波背景辐射、星系、星系团等方面，我们结合理论、数值模拟和观测分析，深入理解暗物质、暗能量性质对大尺度结构和不同探针的影响；探索不同的宇宙学统计分析方法，研究可能的系统误差；充分利用国际观测项目数据，积极参与国内大型观测计划的推进与研究。

Regarding gravitational lensing, cosmic microwave background radiation, galaxies and clusters of galaxies, we investigate the impacts of dark matter and dark energy on the formation and evolution of large-scale structures through theoretical investigations, numerical simulations, and observational analyses. Developing new statistical tools for cosmological studies and understanding possible systematics that could affect their applicability are also our main efforts. Observational data from international communities have been extensively used in our research. We also actively involve in different domestic projects.

随着观测设施的发展，特别是SKA的建设，中性氢21cm观测将进入蓬勃发展阶段，这为理解第一代结构形成和宇宙物质组成及性质提供了新的探针。本团组成员深度参与SKA项目，针对未来观测，建立统计分析方法，引入机器学习算法，充分挖掘利用21cm观测开展宇宙学研究的能力和优势。

With the observational developments, especially with the construction of the SKA project，21cm cosmology will enter its golden age. Arising from the hyperfine energy structure of hydrogen atoms, the characteristics of 21cm signals are sensitive to the birth of the first generation of structures and the nature of the matter components in the Universe. Being heavily involved in SKA, we aim to investigate in depth the potential of extracting cosmological information from 21cm observations by exploring different statistical methods. We also employ machine-learning techniques in our studies.

代表性论文(Selected publications):

• Shimabukuro, H.; Ichiki, K.; Kadota, K., “21cm forest probes on axion dark matter in the post-inflationary Peccei-Quinn symmetry breaking scenarios ”,. 2020, Phys. Rev. D, 102, 023522

• Yuan, S.; Pan, C.Z.; Liu, X.K.; Wang, Q.; Fan, Z.H.. “Cosmological studies from tomographic weak lensing peak abundances and impacts of photo-z errors ”, 2019, ApJ, 884, 164.

• Liu, D.Z.; Fu, L.P.; Liu, X.K.; Radovich, M.; Wang, Q.; Pan, C.Z.; Fan, Z.H.; Covone, G.; Vaccari, M.; Botticella, M. T.; Capaccioli, M.; De Cicco, D.; Grado, A.; Miller, L.; Napolitano, N.; Paolillo, M., Pignata, G., “Weak lensing study in VOICE survey – II. Shear bias calibrations ”, 2018, MNRAS, 478, 2388

• Er, X.Z. ; Hoekstra, H.; Schrabback, T.; Cardone, V.F.; Scaramella, R.; Maoli, R.; Vicinanza, M.; Gillis, B.; Rhodes, J., “Calibration of colour gradient bias in shear measurement using HST/CANDELS data ”, 2018, MNRAS, 476, 5645  

• Shan, H.-Y.; Liu, X.-K.; Hildebrandt, H.; Pan, C.-Z.; Martinet, N.; Fan, Z.-H.; Schneider, P.;Asgari, M.; Harnois-Déraps, J.; Hoekstra, H.; Wright, A.; Dietrich, J.-P.; Erben, T.; Getman, F.; Grado, A.; Heymans, C.; Klaes, D.; Kuijken, K.; Merten, J.; Puddu, E.; Radovich, M.; Wang, Q., "KiDS-450: Cosmological constraints from weak lensing peak statisitcs-I: Inference from analytical prediction of high-signal-to-noise ratio convergence peaks", 2018, MNRAS, 474, 1116.

• Shimabukuro, H.; Semelin, B., “Analyzing the 21 cm signal at the epoch of reionization with artificial neutral network ”, 2017, MNRAS, 468, 3869

• Liu, X.-K.; Li, B.-J.; Zhao, G.-B.; Chiu, M.-C.; Fang, W.; Pan, C.-Z.; Wang, Q.; Du, W.; Yuan, S.; Fu, L.-P.; Fan, Z.-H., "Constraining f(R) gravity theory using weak lensing peak statistics from the Canada-France-Hawaii-Telescope Lensing Survey", 2016, Phys. Rev. Lett., 117, 051101.

• Shimabukuro, H.; Yoshiura, S.; Takahashi, K., Yokoyama, S., Ichiki, K., “21cm bispectrum as method to probe cosmic dawn and epoch of reionization ”, 2016, MNRAS, 458, 3003.

• Liu, X.-K.; Pan, C.-Z.; Li, R.; Shan, H.-Y.; Wang, Q.; Fu, L.-P.; Fan, Z.-H.; Kneib, J.-P.; Leauthaud, A.; Van Waerbeke, L.; Makler, M.; Moraes, B.; Erben, T.; Charbonnier, A., "Cosmological constraints from weak lensing peak statistics with Canada-France-Hawaii Telescope Stripe 82 Survey", 2015, MNRAS, 450, 2888.

• Er, X.-Z.; Mao, Shude, "Effects of plasma on gravitational lensing", 2014, MNRAS, 437, 2180.    

• Shi, X. & Komatsu, E., "Analytical model of non-thermal pressure in galaxy clusters", 2014, MNRAS, 442, 521.

• Fan, Z.-H.; Shan, H.-Y.; Liu, J.-Y., "Noisy weak-lensing convergence peak statistics near clusters of galaxies and beyond", 2010, ApJ, 719, 1408.

• Shi, X.; Joachimi, B.; Schneider, P., "Controlling intrinsic-shear alignment in three-point weak lensing statistics", 2010, A&A, 523, A60.