学术
摘 要:
该文利用高精度的大尺度N体数值模拟,研究了WMAP（Wilkinson Microwave Anisotropy Probe）第3年的观测结果对星系团中的巨弧数目的影响,发现预言的巨弧数目比主流的ACDM模型预言的要低80%多。加入绝热气体几乎不会改变巨弧的发生概率,而引入恒星形成和超新星反馈后得到的概率不会大于原来的1.3倍。如此小的贡献是因为虽然有恒星的数值模拟得到的星系团具有更高的中心密度,但同时星系团的形状更趋球对称,这是影响巨弧概率的2个相反的因素。以前基于ACDM模型预言的巨弧概率还不能很好地与观测相符,WMAP第3年的观测结果将更难以解释。[著者文摘]
文章出处:
《天文学进展》-2007年25卷3期 -262-269页
栏目信息:
分 类 号:
文献标识码:
A
文章编号:
1000-8349（2007）03-0262-08
The Change of the Giant arcs＇ number in the three-year WMAP Cosmological Model
LI Guo-liang （1.Shanghai Astronomical Observatory,Chinese Academy of Science,Shanghai 200030,China;2.Graduate School of the Chinese Academy of Sciences,Beijing 100039,China）
Abstract:
We use high-resolution numerical simulations to investigate the optical depth of giant arcs with length-to-width ratio larger than 7.5 in the‘standard’LCDM model and a model based on the three-year Wilkinson Microwave Anisotropy Probe（WMAP）data.We find that the lensing probability in the three-year WMAP model（withσ_80.74）decreases by a factor of 5-10 compared with that in the‘standard’LCDM model withσ_8=0.9.The current works show that the predicted number of giant arcs can marginally approach the observations in the‘standard’LCDM model withσ_8=0.9.Our result means it is difficult to produce enough giant arcs in the new WMAP3 cosmological model to consist with the observations.Furthermore, we find that the incorporation of baryons,star formation and feedback processes increases the leasing cross-section by a factor of 1.2-1.3.The increase is only modest because the effect on the cross-section by higher mass concentrations is partially offset by the more spherical shapes in the total mass distributions.Although there are still some uncertainties in the simulation including baryon process,such level of baryon contribution was also confirmed by many other works.And usually,such a contribution maybe over-estimated for the over-cooling of gas.We conclude that the low central value of ors and mass densityΩ_（m,0）preferred by the WMAP three-year data is too low to be compatible with observations if assumptions of the background source population are correct.[著者文摘]
Key words:
astrophysics;cosmology;galaxy clusters;gravitational lensing
基金资助:
国家自然科学基金重点资助项目（0203004、10125314、10373012、10533030）
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