宇宙微波背景辐射郭宗宽

中国科学院研究生院

2012.06.26

• 宇宙学基本假设和理论基础宇宙学原理（无边，无中心）爱因斯坦引力理论宇宙物质（重子 +光子 +中微子 +暗物质 +暗能量）

• 观测实验的重要性超新星，大尺度结构，宇宙微波背景辐射宇宙射线， 21厘米谱线，射电波，弱引力透镜，引力波，中微子

• 目前的进展和存在的问题宇宙加速膨胀（暴涨，暗能量，修改引力，非均匀宇宙）宇宙大尺度结构形成（冷 / 温 /热暗物质，暗物质粒子的性质，暗物质分布）

交叉学科 --宇宙学

内容

1. 宇宙微波背景（ CMB）辐射的形成2. CMB的发现和探测实验3. CMB的数据分析4. CMB各向异性的物理起源5. CMB的宇宙学解释6. 展望

1. CMB的形成

epH

• recombination

• decoupling

2. CMB的发现和探测实验

the first discovery of CMB radiation in 1964-1965the Nobel Prize in Physics 1978: A.A. Penzias and R.W. Wilson

CMB was predicted by G. Gamow et al. in 1948 T~5 K

interpreted by P.J.E. Peebles, D.T. Wilkinson, et al. in 1965

COBE (Cosmic Background Explorer) - the first generation CMB experiment, launched on 18 Nov. 1989, 4 yearsthe Nobel Prize in Physics 2006: J.C. Mather and G.F. Smoot

J.C. Mather G.F. Smoot (DMR)

Hot big bang

isotropy

① the Far InfraRed Absolute Spectrophotometer (FIRAS) team

② the Differential Microwave Radiometer (DMR) team

• no atmospheric thermal emission

• full-sky map

advantages of satellite experiments:

the COBE satellite experiments:

141°

WMAP (Wilkinson Microwave Anisotropy Probe) - the second generation CMB experiment, launched on 30 June 2001, 9 years

• free-free emission: electron-ion scattering

• synchrotron emission: the acceleration of cosmic ray electrons in magnetic fields

• thermal emission from dust

23 GHz

33 GHz

41 GHz

61 GHz

94 GHz

• angular power spectrum of CMB• foreground mask

We have entered a new era of precision cosmology.!?

Planck - the third generation CMB experiment, launched on 14 May 2009, 30 months, 5 full-sky surveys

LFI: 30, 44, 70 GHz HFI : 100, 143, 217, 353, 545, 857 GHz

• NASA: CMBPol

• ESA: COrE

next generation CMB experiment

Other experiments:

• ground based experiments (QUaD, BICEP, ACT, ACTPol from 2013, SPT, SPTpol from 2012)• balloon borne experiments (BOOMRANG, MAXIMA)

10 meter telescope

South Pole Telescope (SPT)

150 and 220 GHz in 200895, 150 and 220 GHz in 2009

Atacama Cosmology Telescope (ACT)

6 meter telescope

3 frequencies (148, 218, and 277 GHz)

3. CMB的数据分析

),(),(

),(),(

*

Ya

Ya

lmlm

lmlmlm

T

Td

T

T

the temperature anisotropies can be expanded in spherical harmonics

time-ordered data full sky map

titit nmPd

spectrum parameter estimates

time-ordered data

for Gaussian random fluctuations, the statistical properties of thetemperature field are determined by the angular power spectrum

l

lmlm

Tl a

lC

2

12

1

''*

'' mmllTlmllm Caa

For a full sky, noiseless experiments,

cosmological parameter estimation

likelihood function for a full sky:

the sky-cut, MCMC

4. CMB各向异性的物理起源• primary CMB anisotropies (at recombination)

① inflation model (Alan H. Guth in 1981)

② primordial power spectrum of curvature perturbations

③ angular power spectrum of CMB anisotropies

V (φ)

φ

inflation

reheating

for slow-roll inflation, the primordial power spectra of scalar/tensor perturbations:

the coupled, linearized Boltzmann, Einstein and fluid equations:

spherical harmonicsFourier space

the linearized Einstein equations:

the Einstein equations:

① reionization

② thermal Sunyaev-Zel’dovich effect

③ lensing effect

④ integrated Sachs-Wolf effect

• secondary CMB anisotropies (after recombination)

• large angular scalesintegrated SZ effect (<10)

Sachs-Wolf effect (10~100)

• intermediate scales

acoustic oscillations (100~1000)

• small scales (>1000)

Silk damping: the dissipation of small-scale perturbations caused by photons' random walking out of overdense regions.

features of spectrum

For full accuracy, the Boltzmann equation must be solved to follow the evolution of the photon distribution function.

5. CMB的宇宙学解释

precision cosmology

• the content of our Universe

The stronger the contraction, the higher these peaks should be.

the shape of the primordial power spectrum of curvature perturbations

detection of the primordial power spectrum of tensor perturbations

non-adiabaticitynon-Gaussianity

6. 展望

Thank you for your attention.

a main-sequence star (hydrogen) red giant (helium → carbon, oxygen) white dwarf (carbon, oxygen): electron

degeneracy pressure, 1.4 solar masses Type Ia supernova

• a main-sequence star (hydrogen, carbon, oxygen)• Type Ib, Ic, II supernova (a line of hydrogen)• neutron star (including pulsar): neutron

degeneracy pressure, 1~2 solar masses

a main-sequence star (hydrogen, carbon, oxygen)Type Ib, Ic, II supernovablack hole: 3.2 solar masses

Adam G. Riess (High-Z),

Saul Perlmutter (leader of SCP),

Brian P. Schmidt (leader of High-Z)