i*******n
发帖数: 166 | 1 下午MAP(微波背景辐射各向异性探测器)新闻发布会
由Charles L. Bennett, David N. Spergel, 和John N. Bahcall参加
公布了第一批观测结果, 主要成果有三:
1. COBE之后高分辨率全天空的微波背景辐射观测
2. 通过偏振测量确定了较准确的宇宙光子解藕后再次电离时的红移
(也可以大概说成第一批恒星形成的时刻)
3. 宇宙学参数更精确的测量, 和其他途径的观测符合得很好
宇宙年龄137亿年, 误差只有两亿年
MAP标志着宇宙学的确已经进入精确测量阶段了.
附: 最新的一些宇宙学参数 from MAP
总密度参数 Omega_total = 1.02 +/- 0.02
暗能量密度参数 Omega_Lambda = 0.73 +/- 0.04
物质密度参数 Omega_matter = 0.27 +/- 0.04
重子密度参数 Omega_baryon = 0.044 +/- 0.004
原初扰动谱指数 n_s = 0.93 +/- 0.03 (在k=0.05 Mpc^{-1}处)
扰动 | c**********g
发帖数: 222 | 2 no one try to explain it?
THen let me do it.
Dark energy afftects the evolution of the universe and leaves signatures in
the CMB. From the CMB power spectrum, one can find such signature and infer
the existence of the dark energy. (for example, it will affect the distance
to the last scattering surface and leaves signature in the CMB spacial
inhomogeniety.)
of course, to infer it, there are lots of priors. In CMB power spctrum fit,
there are about 10 free parameters such as the density of baryon | c**********g
发帖数: 222 | 3 actually, in these two weeks, there are several papers arguing about
the high reionization redshift that WMAP claimed. THe lyman-alpha forest
observations seem to disagree on this point. Their prefered value for the
reionization redshift is 6 or at least <10.
【在 c**********g 的大作中提到】
: no one try to explain it?
: THen let me do it.
: Dark energy afftects the evolution of the universe and leaves signatures in
: the CMB. From the CMB power spectrum, one can find such signature and infer
: the existence of the dark energy. (for example, it will affect the distance
: to the last scattering surface and leaves signature in the CMB spacial
: inhomogeniety.)
: of course, to infer it, there are lots of priors. In CMB power spctrum fit,
: there are about 10 free parameters such as the density of baryon
|
|
