CMB physics Zong-Kuan Guo 《现代宇宙学》 2017.5.27
Outline §Background § CMB anisotropy theory § CMB experiments Modern cosmology Cosmic Microwave Background (CMB) radiation § CMB anisotropy theory § CMB experiments § Cosmological implications Constraints on cosmological parameters Some anomalies
§ CMB experiments Ground-based experiments Balloon-borne experiments Space-based experiments VS Planck 2013 SPT 2008-2011
Ground-based experiments Project Location Year Status l range Frequency (GHz) Polarization ACBAR Antarctic 2001-2008 Completed 60-2700 150,219,274 No CBI Chile 2002-2008 300-3000 26-36 VSA Spain 2002-2004 130-1800 SPT 2007- Active 650-9500 95,150,220 ACT 2008- 500-10000 148,218,277 DASI 2001-2003 200-900 Yes CAPMAP USA 500-1500 40,100 QUaD 2005-2010 200-2000 100,150 BICEP 2006-2008 21-335 100,150,220 QUIET 2008-2010 60-3500 40,90 BICEP2 2009-2012 150 KECKArray 2010- ABS 2011- 25-200 145 POLARBEAR 2012- 50-2000 90,150 SPTpol 501-5000 95,150 ACTpol 2013- 225-8725 90,146 BICEP3 2016- Future -- 95 CLASS 40, 90, 150,220 𝑟~0.01
Balloon-borne experiments Project Location Year Status l range Frenquency (GHz) Polarization MAXIMA USA 1995,98,99 Completed 50-700 150-420 No BOOMERanG Antarctic 1997-2003 25-1025 90-420 Yes EBEX 2012- Active 25-1000 150,250,410 SPIDER 2013,2015 10-300 90,150,280 PIPER -- 2015- Future 200,270,350,600 MAXIMA BOOMERanG
Space-based experiments Project Funded by Year Status l range Frequency (GHz) Polarization COBE NASA 1989-1993 Completed 2-40 31.5, 53, 90 No WMAP 2001-2010 2-1200 23, 33, 41, 61, 94 Yes Planck ESA 2009- Active 2-2500 30,44,70,100~857 CMBPol -- Future COrE LiteBIRD JAXA 𝑟~0.001 COBE 1989 4yr WMAP 2001 9yr Planck 2009 2.5yr 2006 NASA: CMBPol ESA: COrE JAXA: LiteBIRD
COBE (COsmic Background Explorer)
in thermal equilibrium the first generation CMB experiment, launched on 18 Nov. 1989, 4 years It carried three instruments: Diffuse Infrared Background Experiment (DIRBE) Differential Microwave Radiometer (DMR) Far Infrared Absolute Spectrophotometer (FIRAS) anisotropy Hot big bang in thermal equilibrium J.C. Mather G.F. Smoot
the Nobel Prize in Physics 2006: J.C. Mather and G.F. Smoot the COBE satellite experiments: the Far InfraRed Absolute Spectrophotometer (FIRAS) team the Differential Microwave Radiometer (DMR) team advantages of satellite experiments: no atmospheric thermal emission full-sky map
WMAP (Wilkinson Microwave Anisotropy Probe)
the second generation CMB experiment, launched on 30 June 2001, 9 years 141°
free-free emission: electron-ion scattering 23 GHz 33 GHz 41 GHz 61 GHz free-free emission: electron-ion scattering synchrotron emission: the acceleration of cosmic ray electrons in magnetic fields thermal emission from dust 94 GHz
foreground mask angular power spectrum of CMB
WMAP science team publications 2003, WMAP1, 14 papers, arXiv:astro-ph/0302209 has been cited by 7668 records. 2007, WMAP3, 5 papers 2009, WMAP5, 8 papers 2011, WMAP7, 6 papers 2012, WMAP9, 2 papers 2010 Shaw Prize, 2012 Gruber Prize 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 HFI high sensitivity wide frequency full-sky coverage high resolution ~5′ (15′, 7º) LHC cost $8 billion; Planck cost €700 million
Planck instrument characteristics Planck instrument characteristics. The sensitivities (1σ) are goal values for 12 months integration and for square pixels whose sides are given in the row “Angular Resolution”. Polarisation measurement at 100 GHz on HFI is waiting for approval (the sensitivity level without polarisation measurement at 100 GHz is given in parenthesis).
http://www.cosmos.esa.int/web/planck/home
Planck science team publications 2013, Planck 2013, 31 papers, arXiv:1303.5076 has been cited by 3796 records. 2015, Planck 2015, 28 papers, arXiv:1502.01589 has been cited by 588 records. 201x, Planck 201x, xx papers
若把宇宙微波背景辐射比喻成一位美丽的少女,1964年的发现只是第一次听到了少女的声音,第一代探测卫星COBE已窥到了少女的身姿,而第二代探测卫星WMAP已揭开了少女的面纱,那么,欧洲航天局2009年5月发射的第三代探测卫星Planck已看到了少女的双眸。 ——摘自《大百科物理学第三版》词条“宇宙微波背景辐射”
SPT (South Pole Telescope)
3 frequencies (95, 150 and 220 GHz) arXiv:1105.3182: (360 citations) DR? the effective number of neutrino species arXiv:1212.6267: (218 citations) Mass? 𝑁 eff =3.86±0.42 ∑ 𝑚 𝜈 = 0.32±0.11 eV
ACT (Atacama Cosmology Telescope)
3 frequencies (148, 218, and 277 GHz)
BICEP2 (Background Imaging of Cosmic Extragalactic Polarization)
BICEP1 (2006-2008) BICEP2 (2010-2012) BICEP3 (2015-2021) BICEP Array (2018-2021) SPT The Dark Sector Lab (DSL)
26 cm aperture 150 GHz 383.7 deg2 2010-2012 4 tiles 8×8 array of detector pairs antenna networks band-defining filters bolometers
scan strategy
CMB data analysis
the temperature anisotropies can be expanded in spherical harmonics time-ordered data full sky map spectrum parameter estimates time-ordered data the temperature anisotropies can be expanded in spherical harmonics ~ 10−5 map making ∆𝑇( 𝑛 ) 𝑇 = 𝑙𝑚 𝑎 𝑙𝑚 𝑌 𝑙𝑚 ( 𝑛 ) 𝑑 𝑡 = 𝑃 𝑡𝑖 𝑚 𝑖 + 𝑛 𝑡 𝑎 𝑙𝑚 = 𝑑 𝑛 𝑌 𝑙𝑚 ∗ ( 𝑛 ) ∆𝑇( 𝑛 ) 𝑇 𝑡, elements; 𝑖, pixels m = ( P 𝑇 N −1 P) −1 P 𝑇 N −1 d
Complete documentation of the package can be found at http://healpix.sourceforge.net http://healpix.jpl.nasa.gov/
for Gaussian random fluctuations, the statistical properties of the temperature field are determined by the angular power spectrum 𝑎 𝑙𝑚 ∗ 𝑎 𝑙 ′ 𝑚 ′ = 𝐶 𝑙 𝑇𝑇 𝛿 𝑙 𝑙 ′ 𝛿 𝑚 𝑚 ′ For a full sky, noiseless experiments, 𝐶 𝑙 𝑇𝑇 = 1 2𝑙+1 𝑚 𝑎 𝑙𝑚 2 cosmological parameter estimation likelihood function for a full sky: −2 ln ℒ = 𝑙 (2𝑙+1) ln 𝐶 𝑙 th + 𝒩 𝑙 𝐶 𝑙 + 𝐶 𝑙 𝐶 𝑙 th + 𝒩 𝑙 −1 Planck Likelihood code is available at the website http://pla.esac.esa.int/pla/ Markov-Chain Monte-Carlo method
Metropolis algorithm. From arXiv:astro-ph/0311311
CosmoMC package is available at the website http://cosmologist
Thanks for your attention!