Cosmic Microwave Background John Carlstrom

Transcription

1 Cosmic Microwave Background John Carlstrom What is it? (quick recap) Fossil radiation from the early universe at 1/35,000 of present age Why is it important? Test theories for origin of big bang, i.e., Inflation Determine what stuff makes up the universe How is information encoded / extracted? Angular power spectrum of CMB anisotropy How do we measure it? What have we learned so far? What s next (the best is yet to come!)

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3 The Expanding Universe

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6 Early universe simple physics photon baryon fluid ~15 billion years ago when the universe was ~400,000 years old Light (photons) tightly couple to free electrons thermal equilibrium dark matter begins to condense

7 Universe expanded, cooled => electrons & protons form Hydrogen (photons no longer scatter off electrons) CMB telescopes are time machines

8 Credit: Nils Halverson

9 COBE Satellite

10 COBE - FIRAS Results Best ever measured Planck Spectrum! Error bars smaller than line thickness! EARLY UNIVERSE IS SIMPLE!

11 COBE DMR DATA Total Intensity Dipole CMB anisotropy and Galaxy

12 What is this?

13 start with this smooth to COBE resolution add comparable noise See Wayne Hu s web page (there is a lot of work left to do!)

14 Simulation by Gary Hinshaw Higher s/n & resolution will provide much more information

15 Universe expanded, cooled => electrons & protons form Hydrogen (photons no longer scatter off electrons) CMB telescopes are time machines

16 Hydrogen atoms ionized plasma

17 Courtesy of Clem Pryke Spherical multipole expansion

18 Courtesy of Clem Pryke

19 CMB allows us to see sound in the early universe See Wayne Hu s fantastic web pages at

20 CMB allows us to see sound in the early universe Overtones reveal the nature of the instrument being played See Wayne Hu s fantastic web pages at

21 Testing the inflationary model for origin of our universe Is the universe flat? Do the second and higher peaks in the CMB power spectrum exist? (i.e., were the initial structures coherent?) Is the initial underlying power spectrum flat?

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23 See Wayne Hu s web page

24 Determining what stuff makes up the universe Do we need dark matter? How much? Amount of ordinary matter Do CMB measurements agree with Big Bang Nucleosynthesis? Do we need dark energy component? If the matter components don t add up to provide enough matter to make the universe flat (a la Einstein) then we need a dark energy component!

25 Source unknown, found on office door

26 Single-dish measurements TOCO TopHat BOOMERanG

27 Last year s balloon-based results Universe is flat! But, what about the other features?

28 Interferometry and the Degree Angular Scale Interferometer DASI

29 NRAO Very Large Array (VLA) Interferometry for CMB observations?

30 How does an interferometer work?

31 Single element radio telescope beam Sky Plane A r = ~ 2 r x ( x) E ( ) Aperture Plane c F.T. E(u) r

32 Interferometric arrays beam of each pair of telescopes Sky Plane r r r r P( x) = A( x) cos(2πu 0 x) Aperture Plane r r r r E( u u0 / 2), E( u + u0 / 2)

33 Degree Angular Scale Interferometer (DASI) DASI Optics and Receiver

34 Assembling DASI in high bay at U. Chicago

35 Summer 1999 testing in Chicago

36 To the South Pole - Why? Cold, dry, and high altitude (2 miles thick ice!)! very low atmospheric opacity Extremely high atmospheric stability No Sun for six months (earth shields the sun) Work on instrument in austral summer Observe relentlessly in the winter Fields remain at constant elevation Existing infrastructure and logistics

37 South Pole: High altitude (10,000 ft) & COLD water vapor is frozen out of atmosphere! +32F -50F -80F

38 Water vapor and atmospheric transmission

39 Long dark winter: incredibly stable atmosphere MAPO at dusk

40 DASI arrives in McMurdo, Antarctica (first C17 flight to ice)

41 CARA - Dark Sector Labs (1 km from South Pole)

42 DASI arrives at South Pole towed to Dark Sector

43 Major components assembled in staging tent

44 November 1999 January 2000 Deployment of DASI at South Pole

45 DASI on the completed tower

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47 Inside DASI

48 PEOPLE DASI Team U. Chicago J. E. Carlstrom M. Dragovan N. W. Halverson W. L. Holzapfel J. Kovac E. M. Leitch C. Pryke E. Schartman S. LaRoque G. Davidson J. Yamasaki B. Reddall CBI A. C. S. Readhead S. Padin J. Cartwright T. Pearson W. Schaal M. Shepherd J. Yamasaki Also: M. White(UIUC) M. Joy (MSFC) S. Myers (NRAO)

49 How does an interferometer work?

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55 combine those two points.

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61 put it all together.

62 DASI s first image Feb 3, 2000 DASI SEES THE MOON!

63 DASI at sunset March 2000 CMB observations made from May November 2000

64 DASI field selection low dust and synchrotron emission

65 DASI 1 st season maps

66 DASI power spectrum Spectrum in Power with beam uncertainties shown resolution

67 DASI results Inflation tests: Further strong support for flat universe Higher harmonic acoustic peaks detected! basic inflation model looks good! Nearly scale invariant initial spectrum! What stuff makes up the universe: 4.5% Ordinary matter (consistent with Big Bang Nucleosynthesis!) 30% Dark matter 65% Dark energy! (?) Next test for DASI? Polarization predicted at ~10% level Inflation looking good! A lot of strange stuff!

68 Captured

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70 CMB! best determined age of the universe

71 What s next? More precise CMB anisotropy measurements Satellites (MAP and Planck) CMB Polarization (next talk) Small angular scale CMB measurements secondary effects Sunyaev-Zel dovich Effect (SZE) What is this Dark Energy? (can we use SZE to get at Dark Energy?)

72 Microwave Anisotropy Probe (MAP)

73 SN SDSS LSS SZE

74 Sunyaev-Zel dovich Effect Adapted from L. Van Speybroeck

75 Thermal Sunyaev-Zel dovich Effect shift decrement increment

76 Galaxy clusters

77 X-ray emission from Abell 2218

78 Owens Valley Radio Observatory MM-wave array

79 One of our cm-wave receivers mounted at the Cassegrain focus of one of the 10.4 m Leighton telescopes at OVRO We ll use this receiver in CMB lab today.

80 CL , z = 0.55 SZE contours on x-ray false color (ROSAT PSPC)

81 Sunyaev-Zel dovich Effect signature is independent of redshift Powerful and Unique Cosmological Probe SZE SURVEYS SZE contours 75 uk for each panel; X-ray insets with same intensity scale

82 SZA Telescope Design Diameter: 3.5 m Frequency: GHz 8 elements: good imaging Extremely close packed

83 Effect of varying Ω M on SZE yield for flat ΛCDM universe! Lower Ω M results in retarded growth and larger volume Expected SZE Yield Separating Survey volume from Cluster density Haiman, Mohr & Holder 2000 astro-ph/

84 Holder et al. Expected results from 1 st year SZA Survey

85 Effect of varying w on SZE yield for flat universe w p ρ ρ R 31+w ( ) Larger volume of w = -1 (Λ model) dominates at low z Retarded growth of density perturbations dominates at high z Separating Survey volume Expected SZE Yield from Cluster density Haiman, Mohr & Holder 2000 astro-ph/

86 DASI & the Martin A Pomerantz Observatory, South Pole

87 New Dark Sector Lab

88 New 8-m Cosmology Telescope for South Pole attached to the new Dark Sector Laboratory

89 Super SZE survey machine on South Pole 8m telescope 1000 element bolometer array 4000 sq deg in one season! detect ~20,000 clusters! 4 inches credit A. Lee & B. Holzapfel

90 Expected results from 1 st year SPT Survey BUT thanks G. Holder, J. Mohr

91 But need to understand gas evolution! need high resolution and detailed studies with SZA Ω M = 0.33, σ 8 = 0.9 SPT ΛCDM w/preheating ΛCDM self-similar Planck see Holder & Carlstrom

92 Summary Primary and secondary CMB anisotropy is a fantastic tool for cosmology Have learned a great deal about the universe! need new physics! now going after the Dark Energy You will hear what we hope to learn from future CMB polarization measurements in the next talk.

93 DASI ground shields installed Nov-Jan 2001

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