We study the potential of the galaxy cluster sample expected from the Chinese Space Station Telescope(CSST)survey to constrain dark energy properties.By modeling the distribution of observed cluster mass for a given t...We study the potential of the galaxy cluster sample expected from the Chinese Space Station Telescope(CSST)survey to constrain dark energy properties.By modeling the distribution of observed cluster mass for a given true mass to be log-normal and adopting a selection threshold in the observed mass M_(200m)≥0.836×10^(14)h^(-1)M_(⊙),we find about 4.1×10^(5)clusters in the redshift range 0≤z≤1.5 can be detected by the CSST.We construct the Fisher matrix for the cluster number counts from CSST,and forecast constraints on dark energy parameters for models with constant(w_(0)CDM)and time dependent(w_(0)w_(a)CDM)equation of state.In the self-calibration scheme,the dark energy equation of state parameter w_(0)of the w_(0)CDM model can be constrained toΔw_(0)=0.036.If w_(a)is added as a free parameter,we obtainΔw_(0)=0.077 andΔw_(a)=0.39 for the w_(0)w_(a)CDM model,with a Figure of Merit for(w_(0),w_(a))of 68.99.Should we have perfect knowledge of the observable-mass scaling relation("known SR"scheme),we would obtainΔw_(0)=0.012 for the w_(0)CDM model,andΔw_(0)=0.062 andΔw_(a)=0.24 for the w_(0)w_(a)CDM model.The dark energy Figure of Merit of(w_(0),w_(a))increases to 343.25.This indicates again the importance of calibrating the observable-mass scaling relation for optically selected galaxy clusters.By extending the_(max)imum redshift of the clusters from z_(max)~1.5 to Z_(max)~2,the dark energy Figure of Merit for(w_(0),w_(a))increases to 89.72(self-calibration scheme)and 610.97("known SR"scheme),improved by a factor of~1.30 and~1.78,respectively.We find that the impact of clusters’redshift uncertainty on the dark energy constraints is negligible as long as the redshift error of clusters is smaller than 0.01,achievable by CSST.We also find that the bias in logarithm mass must be calibrated to be 0.30 or better to avoid significant dark energy parameter bias.展开更多
AgBi_(3)S_(5) is a new n-type thermoelectric material that is environmentally friendly and composed of elements of earth-abundant,non-toxic and high performance-cost ratio.This compound features an intrinsically low t...AgBi_(3)S_(5) is a new n-type thermoelectric material that is environmentally friendly and composed of elements of earth-abundant,non-toxic and high performance-cost ratio.This compound features an intrinsically low thermal conductivity derived from its complex monoclinic structure.However,the terrible electrical transport properties greatly limited the improvement of thermoelectric performance.Most previous studies considered that carrier concentration is the main reason for low electrical conductivity and focused on improving carrier concentration by aliovalent ion doping.In this work,we found that the critical parameter that restricts the electric transport performance of AgBi_(3)S_(5)was the extremely low carrier mobility instead of the carrier concentration.According to the Pisarenko relationships and density functional theory calculations,Nb doping can sharpen the conduction band of AgBi_(3)S_(5),which contributes to reducing the effective mass and improving the carrier mobility.With a further increase of the Nb doping content,the conduction band convergence can enlarge the effective mass and preserve the carrier mobility.Combined with the decrease in lattice thermal conductivity due to the intensive phone scattering,a maximum ZT value of~0.50 at 773 K was achieved in Ag_(0.97)Nb_(0.03)Bi_(3)S_(5),which was~109.6%higher than that of pure AgBi3S5.This work will stimulate the new exploration of high-performance thermoelectric materials in ternary metal sulfides.展开更多
基金supported by the National Natural Science Foundation of China(grant numbers:81602688,81773245,and 81972858)the Natural Science Foundation of Chongqing(cstc2016jcyjA0531)+2 种基金the Science and Technology Innovation Special Project of Chongqing Social Undertak ings and Livelihood Security(cstc2017shmsA130108)the Chongqing Innovation Leading Talents Program(cstccxljrc201910)the Cultivation Program for Clinical Research Talents of Army Medical University(2018XLC1010)。
基金supported by the National Key R&D Program of China grants Nos.2022YFF0503404 and 2021YFC2203102by the National Natural Science Foundation of China (NSFC,Grant Nos.12173036,11773024,11653002,11421303 and 12073036)+2 种基金by the China Manned Space Project grant No.CMSCSST-2021-B01by the Fundamental Research Funds for Central Universities Grant Nos.WK3440000004 and WK3440000005by the CAS Interdisciplinary Innovation Team。
文摘We study the potential of the galaxy cluster sample expected from the Chinese Space Station Telescope(CSST)survey to constrain dark energy properties.By modeling the distribution of observed cluster mass for a given true mass to be log-normal and adopting a selection threshold in the observed mass M_(200m)≥0.836×10^(14)h^(-1)M_(⊙),we find about 4.1×10^(5)clusters in the redshift range 0≤z≤1.5 can be detected by the CSST.We construct the Fisher matrix for the cluster number counts from CSST,and forecast constraints on dark energy parameters for models with constant(w_(0)CDM)and time dependent(w_(0)w_(a)CDM)equation of state.In the self-calibration scheme,the dark energy equation of state parameter w_(0)of the w_(0)CDM model can be constrained toΔw_(0)=0.036.If w_(a)is added as a free parameter,we obtainΔw_(0)=0.077 andΔw_(a)=0.39 for the w_(0)w_(a)CDM model,with a Figure of Merit for(w_(0),w_(a))of 68.99.Should we have perfect knowledge of the observable-mass scaling relation("known SR"scheme),we would obtainΔw_(0)=0.012 for the w_(0)CDM model,andΔw_(0)=0.062 andΔw_(a)=0.24 for the w_(0)w_(a)CDM model.The dark energy Figure of Merit of(w_(0),w_(a))increases to 343.25.This indicates again the importance of calibrating the observable-mass scaling relation for optically selected galaxy clusters.By extending the_(max)imum redshift of the clusters from z_(max)~1.5 to Z_(max)~2,the dark energy Figure of Merit for(w_(0),w_(a))increases to 89.72(self-calibration scheme)and 610.97("known SR"scheme),improved by a factor of~1.30 and~1.78,respectively.We find that the impact of clusters’redshift uncertainty on the dark energy constraints is negligible as long as the redshift error of clusters is smaller than 0.01,achievable by CSST.We also find that the bias in logarithm mass must be calibrated to be 0.30 or better to avoid significant dark energy parameter bias.
基金supported by the National Natural Science Foundation of China(51972094 and 52002107)Hebei Provincial Department of Science and Technology(236Z4403G)+1 种基金Research Innovation Team Project of Hebei University(IT2023A04,150000321008)supported in part by the Micro-analysis Center and the High-Performance Computing Center of Hebei University。
基金supported by the National Natural Science Foundation of China(No.52102234 and 51972094),High-level Talents Research Initiation Project of Hebei University(No.521000981421 and 521000981332)and Hebei Province Introduced Overseas Students Funding Project(C20210313).Chen M appreciates the support of the Nature Science Foundation of Hebei Province(A2017201104),and the Natural Science Foundation of Educational Department of Hebei Province(QN2020156).
文摘AgBi_(3)S_(5) is a new n-type thermoelectric material that is environmentally friendly and composed of elements of earth-abundant,non-toxic and high performance-cost ratio.This compound features an intrinsically low thermal conductivity derived from its complex monoclinic structure.However,the terrible electrical transport properties greatly limited the improvement of thermoelectric performance.Most previous studies considered that carrier concentration is the main reason for low electrical conductivity and focused on improving carrier concentration by aliovalent ion doping.In this work,we found that the critical parameter that restricts the electric transport performance of AgBi_(3)S_(5)was the extremely low carrier mobility instead of the carrier concentration.According to the Pisarenko relationships and density functional theory calculations,Nb doping can sharpen the conduction band of AgBi_(3)S_(5),which contributes to reducing the effective mass and improving the carrier mobility.With a further increase of the Nb doping content,the conduction band convergence can enlarge the effective mass and preserve the carrier mobility.Combined with the decrease in lattice thermal conductivity due to the intensive phone scattering,a maximum ZT value of~0.50 at 773 K was achieved in Ag_(0.97)Nb_(0.03)Bi_(3)S_(5),which was~109.6%higher than that of pure AgBi3S5.This work will stimulate the new exploration of high-performance thermoelectric materials in ternary metal sulfides.
