cosmic宇宙学.ppt

二十一世纪第二个十年的宇宙学
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The origin of “cosmic acceleration”: void? backreaction? modified gravity? dark energy? or simply Lambda?
张鹏杰
中国科学院上海天文台
二十一世纪第二个十年的宇宙学
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The standard cosmology
Six parameters describe (almost) everything (cosmological observations).
二十一世纪第二个十年的宇宙学
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宇宙学探针
膨胀历史和几何
一型超新星
重子声波振荡
强引力透镜
星系团SZ+X-ray
、、
年龄(球状星团、星系)
、、
标准警报、脉泽测距、real time cosmology、、
大尺度结构
弱引力透镜
红移畸变
ISW效应
星系团计数
星系成团性
星系和星系团速度
热SZ和运动学SZ效应
、、、
宇宙初始条件:微波背景辐射、、中微子背景、引力波背景、、
星系动力学(kpc-Mpc尺度)、、、
二十一世纪第二个十年的宇宙学
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Initial condition of
the universe
Physical principles
The observable
universe
Copernican principle
implies that
the observable universe
is a fair sample of
THE universe
?
?
Uncertainties in modern cosmology
?
Nonlinearity in GR,
Nonlinearity in matter fluid
Gastrophysics
?
Gaussian, adiabatic,
nearly scale invariant
primordial fluctuations
GR+SM
+Cold dark matter+Cosmological constant
Dynamical dark energy
PMG? B-mode?
Standard Cosmology
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二十一世纪第二个十年的宇宙学
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Unexpected dimming of type Ia supernovae was first detected in 1998
Riess et al. 2005
Riess et al. 1998
Perlmutter et al. 1999
二十一世纪第二个十年的宇宙学
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What causes the Supernova dimming?
Violations of the Copernican Principle:
What if we live at or near the center of a gigantic void?
Cosmic acceleration
The cosmological constant or dynamical dark energy
Alternatives:
GR backreaction(?)
Modified gravity
Astrophysics:
Intrinsic evolution (?); Dust extinction. Compton dimming. [Not sufficient].....
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二十一世纪第二个十年的宇宙学
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Low density
region
(void)
(1) LTB: "cosmic acceleration" without dark energy
Lemaitre-Tolman-Bondi model:
The universe has a center
We live at or near the center
Matter distribution is isotropic with respect to and only to the center (us)
In this radially nhomogeneous universe, supernovae can appear dimmer than in a FRW universe, without cosmic acceleration.
Gravitational
potential
distance
background universe
(higher density)
compensating shell
二十一世纪第二个十年的