Strong lensing is one of the most spectacular views in the universe.Many cosmological applications have been proposed,but the number of such lensing systems is still limited.In this work,we applied an improved version...Strong lensing is one of the most spectacular views in the universe.Many cosmological applications have been proposed,but the number of such lensing systems is still limited.In this work,we applied an improved version of a previously developed spectroscopic lensing search method to the SDSS-Ⅲ BOSS and proposed a list of highly possible candidates.Follow-up CFHT Megacam imaging observations were performed for five systems,and two out of five are probably strong lensing systems with at least one image close to the central galaxy,although no counter images are detected.展开更多
The elliptical power-law model of the mass in a galaxy is widely used in strong gravitational lensing analyses.However,the distribution of mass in real galaxies is more complex.We quantify the biases due to this model...The elliptical power-law model of the mass in a galaxy is widely used in strong gravitational lensing analyses.However,the distribution of mass in real galaxies is more complex.We quantify the biases due to this model mismatch by simulating and then analyzing mock Hubble Space Telescope imaging of lenses with mass distributions inferred from SDSS-Ma NGA stellar dynamics data.We find accurate recovery of source galaxy morphology,except for a slight tendency to infer sources to be more compact than their true size.The Einstein radius of the lens is also robustly recovered with 0.1%accuracy,as is the global density slope,with 2.5%relative systematic error,compared to the 3.4%intrinsic dispersion.However,asymmetry in real lenses also leads to a spurious fitted"external shear"with typical strengthγext=0.015.Furthermore,time delays inferred from lens modeling without measurements of stellar dynamics are typically underestimated by~5%.Using such measurements from a sub-sample of 37 lenses would bias measurements of the Hubble constant H0 by~9%.Although this work is based on a particular set of Ma NGA galaxies,and the specific value of the detected biases may change for another set of strong lenses,our results strongly suggest the next generation cosmography needs to use more complex lens mass models.展开更多
From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectr...From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectrum,photometry and other information of each QSO will be visually checked carefully.Special attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the QSOs.Through careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial analysis.Components A and B are336 apart and they display blue during photometric observations.The redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less different.For the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,Hγ,OⅢ,and Hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around 2.2.However,no galaxies have been found between components A and B.Inada et al.identified them as binary quasars.But we accidentally find a galaxy group near components A and B.If the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed QSOs.We estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available.展开更多
引力透镜效应是探测星系团物质分布的有效方法之一.目前,利用引力透镜数据重构星系团质量分布的主流方法可以分为两大类,即参数法和非参数法.在实际研究工作中,受限于质量模型假设和计算分辨率等方面的影响,现有的重构算法仍有诸多亟需...引力透镜效应是探测星系团物质分布的有效方法之一.目前,利用引力透镜数据重构星系团质量分布的主流方法可以分为两大类,即参数法和非参数法.在实际研究工作中,受限于质量模型假设和计算分辨率等方面的影响,现有的重构算法仍有诸多亟需解决的问题.基于Shapelets基函数的引力透镜质量重构方法通过基函数来实现引力透镜质量重构,使用Shapelets基函数分解引力透镜势,以引力透镜中多重像的位置和背景星系椭率畸变为限制条件来迭代求解基函数系数从而得到透镜体的质量分布.通过拟合一个模拟的NFW(Navarro,Frenk and White)透镜系统测试了新方法的可行性,结果表明新方法可以在整体上重构出透镜体的质量分布,并拟合出接近真实的源位置,能够为星系团质量测量提供一套灵活且高效的重构算法.展开更多
We investigate the formation of multiple images as the radio signals from fast radio bursts(FRBs)pass through the plane of a plasma clump.The exponential model for the plasma clump is adopted to analyze the properties...We investigate the formation of multiple images as the radio signals from fast radio bursts(FRBs)pass through the plane of a plasma clump.The exponential model for the plasma clump is adopted to analyze the properties of the multiple images.By comparing with the classical dispersion relations,we find that one image has exhibited specific inverse properties to others,such as their delay times at high frequency is higher than that at low frequency,owing to the lensing effects of the plasma clump.We demonstrate that these inverse effects should be observable in some repeating FRBs.Our results predict deviation in the estimated dispersion measure(DM)across multiple images,consistent with the observations of FRB 121102 and FRB 180916.J0158+65.If other plasma lenses have effects similar to an exponential lens,we find that they should also give rise to a similar dispersion relation in the multiple images.For some repeating FRBs,analysis of the differences in time delay and in DM between multiple images at different frequencies can serve as a method to reveal the plasma distribution.展开更多
A class of braneworld black holes, which I called as Bronnikov–Melnikov–Dehen(BMD) black holes,are studied as gravitational lenses. I obtain the deflection angle in the strong deflection limit, and further calculate...A class of braneworld black holes, which I called as Bronnikov–Melnikov–Dehen(BMD) black holes,are studied as gravitational lenses. I obtain the deflection angle in the strong deflection limit, and further calculate the angular positions and magnifications of relativistic images as well as the time delay between different relativistic images. I also compare the results with those obtained for Schwarzschild and two braneworld black holes, i.e., the tidal Reissner-Nordstr¨om(R-N) and the Casadio–Fabbri–Mazzacurati(CFM) black holes.展开更多
基金partly supported by the National Key Basic Research and Development Program of China(No.2018YFA0404501 to SM)the National Natural Science Foundation of China(Grant Nos.11821303 and 11761131004 to SM)
文摘Strong lensing is one of the most spectacular views in the universe.Many cosmological applications have been proposed,but the number of such lensing systems is still limited.In this work,we applied an improved version of a previously developed spectroscopic lensing search method to the SDSS-Ⅲ BOSS and proposed a list of highly possible candidates.Follow-up CFHT Megacam imaging observations were performed for five systems,and two out of five are probably strong lensing systems with at least one image close to the central galaxy,although no counter images are detected.
基金the support of the National Natural Science Foundation of China(Nos.11988101,11773032,12022306)the science research grants from the China Manned Space Project(Nos.CMS-CSST-2021-B01,CMS-CSST-2021-A01)+5 种基金the support from K.C.Wong Education Foundationfunding from the UK Space Agency through award ST/W002612/1from STFC through award ST/T002565/1support by the European Research Council(ERC)through Advanced Investigator grant to CSF,DMIDAS(GA 786910)supported by the European Research Council Horizon 2020 grant“EWC”(award AMD-776247-6)supported by an STFC/UKRI Ernest Rutherford Fellowship,Project Reference:ST/S004998/1。
文摘The elliptical power-law model of the mass in a galaxy is widely used in strong gravitational lensing analyses.However,the distribution of mass in real galaxies is more complex.We quantify the biases due to this model mismatch by simulating and then analyzing mock Hubble Space Telescope imaging of lenses with mass distributions inferred from SDSS-Ma NGA stellar dynamics data.We find accurate recovery of source galaxy morphology,except for a slight tendency to infer sources to be more compact than their true size.The Einstein radius of the lens is also robustly recovered with 0.1%accuracy,as is the global density slope,with 2.5%relative systematic error,compared to the 3.4%intrinsic dispersion.However,asymmetry in real lenses also leads to a spurious fitted"external shear"with typical strengthγext=0.015.Furthermore,time delays inferred from lens modeling without measurements of stellar dynamics are typically underestimated by~5%.Using such measurements from a sub-sample of 37 lenses would bias measurements of the Hubble constant H0 by~9%.Although this work is based on a particular set of Ma NGA galaxies,and the specific value of the detected biases may change for another set of strong lenses,our results strongly suggest the next generation cosmography needs to use more complex lens mass models.
基金provided by the National Development and Reform Commissionthe support of the National Natural Science Foundation of China(NSFC,11803004)+2 种基金Yunnan Province Youth Talent Project(2019182)the support by NSFC through grant No.12203011Yunnan provincial Department of Science and Technology through grant No.202101BA070001-261。
文摘From 2011 to 2021,LAMOST has released a total of 76,167 quasar data.We try to search for gravitationally lensed QSOs by limiting coordinate differences and redshift differences of these QSOs.The name,brightness,spectrum,photometry and other information of each QSO will be visually checked carefully.Special attention should be paid to check whether there are groups of galaxies,gravitationally lensed arcs,Einstein crosses,or Einstein rings near the QSOs.Through careful selection,we select LAMOST J160603.01+290050.8(A)and LAMOST J160602.81+290048.7(B)as a candidate and perform an initial analysis.Components A and B are336 apart and they display blue during photometric observations.The redshift values of components A and B are0.2%different,their Gaia_g values are 1.3%different,and their ugriz values are 1.0%or less different.For the spectra covering from 3690 to 9100?,the emission lines of C II,Mg,Hγ,OⅢ,and Hβare present for both components A and B and the ratio of flux(B)to flux(A)from LAMOST is basically a constant,around 2.2.However,no galaxies have been found between components A and B.Inada et al.identified them as binary quasars.But we accidentally find a galaxy group near components A and B.If the center of dark matter in the galaxy group is at the center between components A and B,components A and B are probably gravitationally lensed QSOs.We estimate that the Einstein mass is 1.46×10^(11)M_⊙and the total mass of the lens is1.34×10^(13)M_⊙.The deflection angle is 197 at positions A and B and the velocity dispersion is 261 km s^(-1).Theoretically,this candidate could be a pair of fold images of a strong lensing system by a galaxy group,and we will investigate the possibility when the redshifts of nearby galaxies are available.
文摘引力透镜效应是探测星系团物质分布的有效方法之一.目前,利用引力透镜数据重构星系团质量分布的主流方法可以分为两大类,即参数法和非参数法.在实际研究工作中,受限于质量模型假设和计算分辨率等方面的影响,现有的重构算法仍有诸多亟需解决的问题.基于Shapelets基函数的引力透镜质量重构方法通过基函数来实现引力透镜质量重构,使用Shapelets基函数分解引力透镜势,以引力透镜中多重像的位置和背景星系椭率畸变为限制条件来迭代求解基函数系数从而得到透镜体的质量分布.通过拟合一个模拟的NFW(Navarro,Frenk and White)透镜系统测试了新方法的可行性,结果表明新方法可以在整体上重构出透镜体的质量分布,并拟合出接近真实的源位置,能够为星系团质量测量提供一套灵活且高效的重构算法.
基金supported by the National Natural Science Foundation of China(grant Nos.12041304,11873080 and 12033001)supported by the 2021 project Xinjiang Uygur Autonomous Region of China for Tianshan elites,and the National SKA Program of China(grant Nos.U1838109,2020SKA0120100 and 12041301)+4 种基金supported by the Key Laboratory of Xinjiang Uygur Autonomous Region No.2020D04049the National SKA Program of China No.2020SKA0120200the 2018 Project of Xinjiang Uygur Autonomous Region of China for Flexibly Fetching in Upscale Talentssupported by CAS“Light of West China”Program No.2018-XBQNXZ-B-025partly supported by the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the CAS。
文摘We investigate the formation of multiple images as the radio signals from fast radio bursts(FRBs)pass through the plane of a plasma clump.The exponential model for the plasma clump is adopted to analyze the properties of the multiple images.By comparing with the classical dispersion relations,we find that one image has exhibited specific inverse properties to others,such as their delay times at high frequency is higher than that at low frequency,owing to the lensing effects of the plasma clump.We demonstrate that these inverse effects should be observable in some repeating FRBs.Our results predict deviation in the estimated dispersion measure(DM)across multiple images,consistent with the observations of FRB 121102 and FRB 180916.J0158+65.If other plasma lenses have effects similar to an exponential lens,we find that they should also give rise to a similar dispersion relation in the multiple images.For some repeating FRBs,analysis of the differences in time delay and in DM between multiple images at different frequencies can serve as a method to reveal the plasma distribution.
基金Supported by Natural Science Foundation of Education Department of Shannxi Provincial Government under Grant No.15JK1077Doctorial Scientific Research Starting Fund of Shannxi University of Science and Technology under Grant No.BJ12-02
文摘A class of braneworld black holes, which I called as Bronnikov–Melnikov–Dehen(BMD) black holes,are studied as gravitational lenses. I obtain the deflection angle in the strong deflection limit, and further calculate the angular positions and magnifications of relativistic images as well as the time delay between different relativistic images. I also compare the results with those obtained for Schwarzschild and two braneworld black holes, i.e., the tidal Reissner-Nordstr¨om(R-N) and the Casadio–Fabbri–Mazzacurati(CFM) black holes.
