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Quasi-2D weak lensing cosmological constraints using the PDF-SYM method

Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 44-58页

作者： Zhenjie Liu Jun Zhang Hekun Li Zhi Shen Cong Liu Department of Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai 200240China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

Cosmic shear statistics,such as the two-point correlation function(2PCF),can be evaluated with the PDF-SYM method instead of the traditional weighted-sum approach.It makes use of the full PDF information of the shear estimators,and does not require weightings on the shear estimators,which can in principle introduce additional systematic biases.This work presents our constraints on S8and?mfrom the shear-shear correlations using the PDF-SYM method.The data we use is from the z-band images of the Dark Energy Camera Legacy Survey(DECa LS),which covers about 10000 deg2with more than 100 million galaxies.The shear catalog is produced by the Fourier Quad method,and well tested on the real data itself with the field-distortion effect.Our main approach is called quasi-2D as we do use the photo-z information of each individual galaxy,but without dividing the galaxies into redshift bins.We mainly use galaxy pairs within the redshift interval between 0.2 and 1.3,and the angular range from 4.7 to 180 arcmin.Our analysis yields S8=0.762±0.026 and?m=0.234±0.075,with the baryon effects and the intrinsic alignments included.The results are robust against redshift uncertainties.We check the consistency of our results by deriving the cosmological constraints from auto-correlations ofγ1andγ2separately,and find that they are consistent with each other,but the constraints from theγ1component are much weaker than that fromγ2.It implies a much worse data quality ofγ1,which is likely due to additional shear uncertainties caused by CCD electronics(according to the survey strategy of DECa LS).We also perform a pure 2D analysis,which gives S8=0.81_(-0.04)~(+0.03)and?m=0.25_(-0.05)~(+0.06).Our findings demonstrate the potential of the PDF-SYM method for precision cosmology.

关键词： weak lensing shear-shear correlations cosmological parameters observations analysis

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A Search for Radio Pulsars in Supernova Remnants Using FAST with One Pulsar Discovered

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Chinese Physics Letters 2024年第2期41卷 133-136页

作者：张振闫文明袁建平王娜白俊涛温志刚李保达解进涛赵德王榆斌翟楠楠 Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Radio Astronomy and Technology(Chinese Academy of Sciences) Beijing 100101China Xinjiang Key Laboratory of Radio Astrophysics Urumqi 830011China College of Physics GuiZhou UniversityGuizhou 550025China Research Center for Intelligent Computing Platforms Zhejiang LaboratoryHangzhou 311100China School of Physical Science and Technology Xinjiang UniversityUrumqi 830046China School of Physics and Electronic Engineering Sichuan University of Science&EngineeringZigong 643000China

We report the results of a search for radio pulsars in five supernova remnants(SNRs)with the FAST telescope.The observations were made using the 19-beam receiver in“snapshot”mode.The integration time for each pointing was 10 min.We discovered a new pulsar,PSR J1845–0306,which has a spin period of 983.6 ms and a dispersion measure of 444.6±2.0 cm^(−3)·pc,in observations of SNR G29.6+0.1.To judge the association between the pulsar and the SNR,further verification is needed.We also re-detected some known pulsars in the data from SNRs G29.6+0.1 and G29.7–0.3.No pulsars were detected in the observations of the other three SNRs.

关键词： observations Pulsar pulsar

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Remarkable effects of multiple photon spheres on black hole observations

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Science China(Physics,Mechanics & Astronomy) 2022年第12期65卷 153-153页

作者： Yi-Fu Cai Department of Astronomy School of Physical SciencesUniversity of Science and Technology of ChinaHefei230026China CAS Key Laboratory for Researches in Galaxies and Cosmology School of Astronomy and Space ScienceUniversity of Science and Technology of ChinaHefei230026China

The recent release of the first image of the super-massive black hole M87^(*),photographed by the Event Horizon Telescope Collaboration,has attracted a lot of attention in black hole appearances.In a spherically symme... 详细信息

关键词： massive black observations

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High-resolution observations from space to address new applications in hydrology

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The Innovation 2023年第3期4卷 112-113页

作者： Luca Brocca Wei Zhao Hui Lu Research Institute for Geo-Hydrological Protection National Research CouncilPerugia 06128Italy Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610299China Department of Earth System Science Ministry of Education Key Laboratory for Earth System ModelingInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China

There is an increasing demand from the hydrological community to improve the monitoring and modeling of hydrological processes using remote sensing technologies.However,this task has been severely limited by the coarse resolution of previous remote sensing observations.In recent years,along with the increased availability of high-resolution modeling in hydrology,the advent of high-resolution temporal dynamic satellite observations has been providing unprecedented new opportunities to address new applications and challenges in hydrology.

关键词： resolution hydrology observations

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The 9–11 November 2013 Explosive Cyclone over the Japan Sea- Okhotsk Sea: observations and WRF Modeling Analyses

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Journal of Ocean University of China 2020年第5期19卷 989-1004页

作者： FU Gang JING Miaomiao LI Pengyuan Department of Marine Meteorology Ocean-Atmosphere Interaction and Climate LaboratoryKey Laboratory of Physical OceanographyOcean University of ChinaQingdao 266100China Division of Oceanic Dynamics and Climate Qingdao National Laboratory for Marine Science and TechnologyQingdao 266100China Qingdao Hatran Ocean Intelligence Technology Company Limited Qingdao 266404China

During the period from 9 to 11 November 2013,an explosive cyclone(EC)occurred over the Japan Sea-Okhotsk Sea.This EC initially formed around 18 UTC 9 November over the Japan Sea and developed over the Okhotsk Sea when moving northeastward.It had a minimum sea level pressure of 959.0 hPa,a significant deepening rate of central pressure of 2.9 Bergeron,and a maximum instantaneous wind speed of 42.7 m s−1.This paper aims to investigate the conditions that contributed to the rapid development of this low-pressure system through analyses of both observations and the Weather Research Forecasting(WRF)modeling results.The evolutionary processes of this EC were examined by using Final Analyses(FNL)data,Multi-Functional Transport Satellites-1R(MTSAT-1R)data,upper observation data and surface observation data.WRF-3.5 modeling results were also used to examine the development mechanism of this EC.It is shown that the interaction between upper-level and low-level potential vorticity seemed to be very essential to the rapid development of this EC.

关键词： explosive cyclone the Japan Sea-Okhotsk Sea observations WRF-3.5 modeling results potential vorticity

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An Adjoint-Free CNOP–4DVar Hybrid Method for Identifying Sensitive Areas in Targeted observations: Method Formulation and Preliminary Evaluation

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Advances in Atmospheric Sciences 2019年第7期36卷 721-732页

作者： Xiangjun TIAN Xiaobing FENG ICCES Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China University of Chinese Academy of Sciences Beijing100049China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing210044 China Department of Mathematics University of TennesseeKnoxvilleTN37996USA

This paper proposes a hybrid method, called CNOP–4 DVar, for the identification of sensitive areas in targeted observations, which takes the advantages of both the conditional nonlinear optimal perturbation(CNOP) and four-dimensional variational assimilation(4 DVar) methods. The proposed CNOP–4 DVar method is capable of capturing the most sensitive initial perturbation(IP), which causes the greatest perturbation growth at the time of verification;it can also identify sensitive areas by evaluating their assimilation effects for eliminating the most sensitive IP. To alleviate the dependence of the CNOP–4 DVar method on the adjoint model, which is inherited from the adjoint-based approach, we utilized two adjointfree methods, NLS-CNOP and NLS-4 DVar, to solve the CNOP and 4 DVar sub-problems, respectively. A comprehensive performance evaluation for the proposed CNOP–4 DVar method and its comparison with the CNOP and CNOP–ensemble transform Kalman filter(ETKF) methods based on 10 000 observing system simulation experiments on the shallow-water equation model are also provided. The experimental results show that the proposed CNOP–4 DVar method performs better than the CNOP–ETKF method and substantially better than the CNOP method.

关键词： CNOP 4DVar NLS-4DVar targeted observations sensitive area identification

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Progress in multi-waveband observations of supernova remnants

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Progress in Natural Science:Materials International 2008年第9期18卷 1057-1062页

作者： Xuejuan Yang a,b, Fangjun Lua, Wenwu Tian c,d,* a Particle Astrophysics Center, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China b Department of Astronomy, Beijing Normal University, Beijing 100875, China c National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, CAS, Beijing 100012, China d Department of Physics & Astronomy, University of Calgary, Alberta, Canada T2N 1N4 Particle Astrophysics Center Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Department of Astronomy Beijing Normal University Beijing 100875 China National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District CAS Beijing 100012 China Department of Physics & Astronomy University of Calgary Alberta Canada T2N 1N4

The development of observational techniques has enriched our knowledge of supernova remnants. In this paper, we review the main progresses in the last decade, including new discoveries of supernova remnants and the associated (rare type of) pulsars, nucleosynthesis, the interaction between supernova remnants and molecular clouds, dust in the supernova remnants, shock physics, and cosmic ray accelerations.

关键词： Supernova remnant observations

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Evaluation of Simulated CO_2 Concentrations from the CarbonTracker-Asia Model Using In-situ observations over East Asia for 2009–2013

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Advances in Atmospheric Sciences 2019年第6期36卷 603-613页

作者： Samuel Takele KENEA Young-Suk OH Jae-Sang RHEE Tae-Young GOO Young-Hwa BYUN Shanlan LI Lev D.LABZOVSKII Haeyoung LEE Robert F.BANKS Climate Research Division National Institute of Meteorological Sciences Environmental Meteorology Research Division National Institute of Meteorological Sciences Meteorology Department Delta Air LinesInc.

The CarbonTracker(CT) model has been used in previous studies for understanding and predicting the sources, sinks, and dynamics that govern the distribution of atmospheric CO_2 at varying ranges of spatial and temporal scales. However, there are still challenges for reproducing accurate model-simulated CO_2 concentrations close to the surface, typically associated with high spatial heterogeneity and land cover. In the present study, we evaluated the performance of nested-grid CT model simulations of CO_2 based on the CT2016 version through comparison with in-situ observations over East Asia covering the period 2009–13. We selected sites located in coastal, remote, inland, and mountain areas. The results are presented at diurnal and seasonal time periods. At target stations, model agreement with in-situ observations was varied in capturing the diurnal cycle. Overall, biases were less than 6.3 ppm on an all-hourly mean basis, and this was further reduced to a maximum of 4.6 ppm when considering only the daytime. For instance, at Anmyeondo, a small bias was obtained in winter, on the order of 0.2 ppm. The model revealed a diurnal amplitude of CO_2 that was nearly flat in winter at Gosan and Anmyeondo stations, while slightly overestimated in the summertime. The model's performance in reproducing the diurnal cycle remains a challenge and requires improvement. The model showed better agreement with the observations in capturing the seasonal variations of CO_2 during daytime at most sites, with a correlation coefficient ranging from 0.70 to 0.99. Also, model biases were within-0.3 and 1.3 ppm, except for inland stations(7.7 ppm).

关键词： model evaluation in-situ observations CarbonTracker East Asia

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Targeted observations for Improving Prediction of the NAO Onset

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Journal of Meteorological Research 2019年第6期33卷 1044-1059页

作者： Guokun DAI Mu MU Zhina JIANG Department of Atmospheric and Oceanic Sciences&Institute of Atmospheric Sciences Fudan UniversityShanghai 200438 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

Based on the viewpoint that the North Atlantic Oscillation(NAO)has an intrinsic timescale of approximate two weeks and can be treated as an initial value problem,targeted observations for improving the prediction of the onset of NAO events are investigated by using the conditional nonlinear optimal perturbation(CNOP)method with a quasigeostrophic model.The results show that flow-dependent sensitive areas for the prediction of NAO onset are mainly located over North Atlantic and its upstream regions.Targeted observations over the main sensitive areas could improve NAO onset prediction in most cases(approximately 75%)due to reduced errors in anomalous eddy vorticity forcing(EVF)projection in the typical NAO mode.Moreover,a flow-independent sensitive area is determined based on the winter climatological flow,which is located over North America and its adjacent ocean.The NAO onset prediction can also be improved by targeted observations over the flow-independent sensitive area,but the skill improvement is somewhat lower than that derived from observations over the flow-dependent sensitive area.The above results indicate that targeted observations over sensitive areas identified by the CNOP method can help to improve the onset prediction of NAO events.

关键词： North Atlantic Oscillation(NAO) targeted observations eddy vorticity forcing(EVF) conditional nonlinear optimal perturbation(CNOP)

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Measuring the tilt of primordial gravitational-wave power spectrum from observations

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Science China(Physics,Mechanics & Astronomy) 2019年第11期62卷 135-137页

作者： Jun Li Zu-Cheng Che Qing-Guo Huang CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal UniversityChangsha 410081China

Primordial gravitational waves (GWs) encode the information about inflation [1], and the power spectrum of primordial GWs have attracted a lot of attentions. There are in general two crucial properties for the primord... 详细信息

关键词： PTA BK Measuring the tilt of primordial gravitational-wave power spectrum from observations

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