Oltre l'orizzonte cosmologico

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Seminario del Prof. Paolo de Bernardis
11 Marzo 2010
Aula A Dipartimento di Fisica
ore 13.15

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Oltre l'orizzonte cosmologico

  1. 1. Oltre l’ orizzonte cosmologico Paolo de Bernardis Dipartimento di Fisica Università di Roma La Sapienza A pranzo con la fisica - NIPS Lab Dipartimento di Fisica Università di Perugia 11/03/2010
  2. 2. L’ orizzonte in cosmologia • L’ orizzonte delle particelle è la superficie che ci separa da quanto non possiamo osservare, perché la luce partita oltre l’ orizzonte non è ancora arrivata fino a noi. Le particelle che si trovano oltre l’ orizzonte non sono ancora in contatto causale con noi. Esiste se l’ universo ha un’età finita. • Esistono però altri orizzonti, di tipo fisico, più vicini di quello delle particelle, che dipendono dai dettagli della propagazione della luce nell’ universo.
  3. 3. Il redshift • Negli anni ’20 Carl Wirtz, Edwin Hubble ed altri, analizzarono la luce proveniente da galassie distanti, e notarono che piu’ una galassia e’ distante, piu’ le lunghezze d’ onda della sua luce sono allungate (spostamento verso il rosso, redshift). •Questo dato empirico viene interpretato come una prova dell’ espansione dell’ universo.
  4. 4. Lunghezza d’ onda λ (nm) Galassia molto lontana Galassia lontana Galassia vicina laboratorio Ca II HI Mg I Na I
  5. 5. Percorrendo distanze cosmologiche, la luce cambia colore • La relativita’ generale di Einstein prevede che, in un universo in espansione, le lunghezze d’onda λ dei fotoni si allunghino esattamente quanto le altre lunghezze. • Piu’ distante e’ una galassia, piu’ e’ lungo il cammino che la luce deve percorrere, piu’ lungo e’ il tempo che impiega, maggiore e’ l’ espansione dell’ universo dal momento dell’ emissione a quello dalla ricezione, e piu’ la lunghezza d’ onda viene allungata. to t1 t2
  6. 6. • Se vogliamo arrivare a osservare l’ orizzonte, dobbiamo osservare più lontano possibile. • La luce che è partita da regioni di universo così remote, avrà allungato moltissimo le sue lunghezze d’ onda, diventando infrarossa, o microonde, o radioonde … • Quindi richiede telescopi e rivelatori speciali per essere osservata.
  7. 7. • L’ orizzonte a cui si arriva, però, è di tipo fisico. • Infatti l’ espansione dell’ universo comporta un suo raffreddamento. Osservando lontano riceveremo luce che è stata emessa quando l’ universo era più caldo di oggi. • Se guardiamo abbastanza lontano, arriveremo ad osservare epoche in cui l’ universo era caldo come o più della superficie del sole. • E quindi era ionizzato. In quell’ epoca i fotoni non potevano propagarsi su linee rette, ma su spezzate venendo continuamente diffusi dagli elettroni liberi del mezzo ionizzato. • L’ universo primordiale è opaco, come opaco è l’ interno di una stella.
  8. 8. Orizzonte fisico • In un universo in espansione, dominato dalla radiazione, si può calcolare accuratamente il tempo necessario per passare dal Big Bang (densità e temperatura infinite) fino alla temperatura in cui elettroni e protoni possono combinarsi in atomi (ricombinazione dell’ idrogeno). • La temperatura a cui avviene la ricombinazione è circa 3000K, e il tempo necessario per arrivarci è di 380000 anni. • Quindi per i primi 380000 anni della sua evoluzione l’ universo è ionizzato e opaco.
  9. 9. Orizzonte fisico • Osservando sempre più lontano, potremo vedere solo finchè l’ universo è trasparente. Cioè fino all’ epoca della ricombinazione. • Possiamo quindi osservare entro un orizzonte che è una superficie sferica, centrata sulla nostra posizione, al di là della quale l’ universo è opaco a causa delle diffusioni (scattering) contro gli elettroni liberi subite dai fotoni. • Si chiama superficie di ultimo scattering ed è il nostro orizzonte fisico.
  10. 10. Composizione della luce che viene dal sole (spettro) Lunghezza d’ onda (micron) Intensità luminosa W/m2/sr/cm-1) Radiazione Termica, Spettro di Corpo Nero
  11. 11. Strong evidence for a hot early phase of the Universe Thermal spectrum …. … and accurate isotropy 0K 3K 5K Cosmic Microwave Background
  12. 12. Orizzonte fisico • Nel seguito: –L’ osservazione della superficie di ultimo scattering. • Come si fa • Quali sono i risultati • Orizzonti causali impressi nell’ orizzonte fisico • Conseguenze per la cosmologia e la fisica fondamentale –Come andare oltre.
  13. 13. How to detect CMB photons • E(γCMB) of the order of 1 meV • Frequency: 15-600 GHz • Detection methods: – Coherent (antenna + amplifier) – Thermal (bolometers) – Direct (Cooper pairs in KIDs) • Space (atmospheric opacity)
  14. 14. How to detect CMB photons • E(γCMB) of the order of 1 meV • Frequency: 15-600 GHz • Detection methods: – Coherent (antenna + amplifier) – Thermal (bolometers) – Direct (Cooper pairs in KIDs) • Space (atmospheric opacity)
  15. 15. Cryogenic Bolometers • The CMB spectrum is a continuum and bolometers are wide band detectors. That’s why they are so sensitive. Thermometer (Ge thermistor (ΔR) at low T) Load resistor Incoming ΔV Photons (ΔB) Feed Integrating Horn filter Radiation cavity (angle selective) (frequency Absorber (ΔT) selective) • Fundamental noise sources are Johnson noise in the thermistor (<ΔV2> = 4kTRΔf), temperature fluctuations in the thermistor ((<ΔW2> = 4kGT2Δf), background radiation noise (Tbkg5) need to reduce the temperature of the detector and the radiative background.
  16. 16. Cryogenic Bolometers Again, need • Johnson noise in the thermistor of low temperature d Δ V J2 and low = 4 kTR df background • Temperature noise d Δ W T2 4 kT 2 G eff = 2 df G eff + (2π fC ) 2 Q • Photon noise d ΔWPh 4k 5TBG x4 (ex −1+ ε ) 2 5 = 2 3 ∫ε dx df ch (e −1) x 2 • Total NEP (fundamental): 1 d ΔVJ2 d ΔWT2 d ΔWPh 2 NEP = 2 2 + + ℜ df df df
  17. 17. Circa 1970 Circa 1980
  18. 18. •The absorber is micro machined as a web of Spider-Web Bolometers metallized Si3N4 wires, 2 μm thick, with 0.1 mm Built by JPL Signal wire pitch. Absorber •This is a good absorber for mm-wave photons and features a very low cross section for cosmic rays. Also, the heat capacity is reduced by a large factor with respect to the solid absorber. •NEP ~ 2 10-17 W/Hz0.5 is achieved @0.3K •150μKCMB in 1 s •Mauskopf et al. Appl.Opt. Thermistor 36, 765-771, (1997) 2 mm
  19. 19. Development of thermal detectors for far IR and mm-waves 17 10 Langley's bolometer Golay Cell a measurement (seconds) 12 10 Golay Cell time required to make Boyle and Rodgers bolometer 1year F.J.Low's cryogenic bolometer 7 10 Composite bolometer 1day 1 hour Composite bolometer at 0.3K 2 10 1 second Spider web bolometer at 0.3K Spider web bolometer at 0.1K Photon noise limit for the CMB 1900 1920 1940 1960 1980 2000 2020 2040 2060 year
  20. 20. How to detect CMB photons • E(γCMB) of the order of 1 meV • Frequency: 15-600 GHz • Detection methods: – Coherent (antenna + amplifier) – Thermal (bolometers) – Direct (Cooper pairs in KIDs) • Space (atmospheric opacity)
  21. 21. COBE-FIRAS • COBE-FIRAS was a cryogenic Martin- Puplett Fourier- Transform Spectrometer with composite bolometers. It was placed in a 400 km orbit. • A zero instrument comparing the specific sky brightness to the brightness of a cryogenic Blackbody
  22. 22. MPI (Martin Puplett Interferometer) Beamsplitter = wire grid polarizer Differential instrument ∞ I SKY ( x) = C ∫ [SSKY (σ ) − SREF (σ )]rt(σ ){ + cos[4πσx]}dσ 1 0 ∞ ICAL( x) = C ∫ [SCAL(σ ) − SREF (σ )]rt(σ ){ + cos[4πσx]}dσ 1 0
  23. 23. FIRAS • The FIRAS guys were able to change the temperature of the internal blackbody until the interferograms were null. • This is a null measurement, which is much more sensitive than an absolute one: (one can boost the gain of the instrument without saturating it !). • This means that the difference between the spectrum of the sky and the spectrum of a blackbody is zero, i.e. the spectrum of the sky is a blackbody with that temperature. • This also means that the internal blackbody is a real blackbody: it is unlikely that the sky can have the same deviation from the Planck law characteristic of the source built in the lab.
  24. 24. σ (cm-1) wavenumber
  25. 25. • The spectrum 2h ν 3 B(ν , T ) = 2 x c e −1 TCMB = 2.725K RJ Wien hν ν xCMB = ≅ kTCMB 56 GHz − xmax xmax 1− e = ⇒ xmax = 2.82 ⇒ 3 ν max = 159 GHz (σ max = 5.31 cm −1 ) λ B(ν , T ) = B(λ , T ) ⇒ λmax = 1.06 mm ν
  26. 26. • Techniques ? RJ Wien ν << ν max = 160 GHz ⇒ coherent detectors ν >> ν max = 160 GHz ⇒ bolometers ν ≈ ν max = 160 GHz ⇒ ? ??
  27. 27. • The DMR instrument aboard COBE-DMR of the COBE satellite CMB anisotropy measured the first map of CMB anisotropy (1992) Galactic Plane • The contrast of the image is very low, but there are structures, at a level of 10ppm. • Instrumental noise is significant in the maps (compare the three different wavelengths) • DMR did not have a real telescope, so the angular resolution was quite coarse (10 o !!)
  28. 28. Cosmic Horizons • The very good isotropy of the CMB sky is to some extent surprising. • The CMB comes from an epoch of 380000 years after the Big Bang. • So it depicts a region of the universe as it was 380000 years after the Big Bang. • The region we can map, however, is much wider than 380000 light years. • So it contains subregions which are separated more than the length light has travelled since the Big Bang. These regions would not be in causal contact in a static universe.
  29. 29. R= distance from us = 14 Glyrs But also distance in R time: 14 Gyrs ago & t here, now K 000 T=3 Transparent universe Opaque universe
  30. 30. R= distance from ly us = 14 Glyrs several G y 4 Gl But also distance in R= 1 R= time: 14 Gyrs ago 1 4G ly here, now K 000 T=3 Transparent universe Opaque universe
  31. 31. r=3 R= distance from 80 k l y ly us = 14 Glyrs several G ly 0k y 38 4 Gl But also distance in r= R= 1 R= time: 14 Gyrs ago 1 4G ly here, now K 000 T=3 Transparent universe Opaque universe
  32. 32. Cosmic Horizons • We measure the same brightness (temperature) in all these regions, and this is surprising, because to attain thermal equilibrium, contact is required ! (through forces, thermal, radiative …). • We live in an expanding universe. Regions separated by more than 380000 light years might have been in causal contact (and thus homogeneized) earlier.
  33. 33. Expansion vs Horizon In a Universe made of o n matter and radiation, the oriz e h expansion rate decreases f th with time. eo siz size of region the considered time
  34. 34. Expansion vs Horizon In a Universe made of o n matter and radiation, the oriz e h expansion rate decreases f th with time. eo siz size of region the considered So a region as large as the horizon when the CMB is released …. 380000 y time
  35. 35. Expansion vs Horizon In a Universe made of o n matter and radiation, the oriz e h expansion rate decreases f th with time. eo siz size of region the considered … has never been causally connected before 380000 y time
  36. 36. Expansion vs Horizon In a Universe made of o n matter and radiation, the oriz e h expansion rate decreases f th with time. eo siz size of region the considered … nor has been causally connected to surrounding regions 380000 y time
  37. 37. Cosmic Horizons • Hence the “Paradox of Horizons” : • We see approximately the same temperature everywhere in the map of the CMB, but we do not understand how this has been obtained in the first 380000 years of the evolution of the universe. • Was this temperature regulated everywhere ab-initio ? • Are our assumptions about the composition of the universe wrong, and the universe does not decelerate in the first 380000 years ?
  38. 38. Granulazione solare Gas incandescente sulla superficie del Sole (5500 K) 8 minuti luce Qui, ora
  39. 39. Granulazione solare Gas incandescente sulla superficie del Sole (5500 K) 8 minuti luce Qui, ora Gas incandescente nell’ universo primordiale (l’ universo diventa trasparente a 3000 K) 14 miliardi di anni luce Qui, ora Mappa di BOOMERanG dell’ Universo Primordiale
  40. 40. Flatness Paradox • The expansion of the Universe is regulated by the Friedmann equation, directly deriving from Einstein’s equations for a homogeneous and isotropic fluid. • If the Universe contains only matter and radiation, it either collapses or dilutes, with a rate depending on the mass-energy density. • To get an evolution with a mass-energy density of the order of the observed one today, billions of years after the Big Bang, you need to tune it at the beginning very accurately, precisely equal to a critical value. • How was this fine-tuning achieved ?
  41. 41. a(t) g ig B an B the ter s af Cosmic distances 1 n nsity, l de Cr itica Billion years t
  42. 42. Inflation might be the solution C In o sm fla ic ti o n Sub-atomic scales t=10-36s Quantum fluctuations of the field dominating the energy of the universe Energy scale: 1016 GeV Cosmic Inflation: A very fast expansion Cosmological scales of the universe, driven by a phase transition in t=380000 y the first split-second density fluctuations
  43. 43. Expansion vs Horizon According to the inflation o n theory …. oriz e h f th eo siz size of region the considered A region as large as the horizon when the CMB is released …. …had been causally connected to the surrounding regions before inflation 380000 y time
  44. 44. al size of n orm tion the considered regio n lu evo o n oriz e h f th eo exponential siz expansion Inflation: 10-36 s time
  45. 45. al size of n orm tion the considered regio n lu evo o n oriz e h f th eo exponential siz expansion Inflation: Here the horizon contains all of the universe observable today 10-36 s time
  46. 46. • Inflation – Provides a physical process to origin density fluctuations – Explains the flatness paradox – Explains the horizons paradox • Is a predictive theory (a list of > models has been compiled..) – Predicts gaussian density fluctuations – Predicts scale invariant density fluctuations – Predicts Ω=1 • How can we test it ? • We still expect a difference between the physical processes happening inside the horizon and those relevant outside the horizon. • So we expect anyway that the scale of the causal horizon is imprinted in the image of the CMB. • The angular size subtended by the horizons when the CMB is released is around 1 degree, if the geometry of space is Euclidean. • We need sharp images of the CMB, so that we can resolve the density fuctuations predicted by inflation.
  47. 47. θ d R d ao 380000 ly θ≈ × ≈ ×1100 ≈1o R a 14000000000 ly
  48. 48. 380000 lyrs R 1o COBE resolution Here, now K 10o 000 ang ∞) T=3 BigB (T= R= distance from us = 14 Glyrs
  49. 49. high resolution • The images from COBE-DMR were not sharp enough to resolve cosmic horizons (the angular resolution was 7°). • After COBE, experimentalists worked hard to develop higher resolution experiments. • In addition to testing inflation, we expected high resolution observations to give informations about a) The geometry of space b) The physics of the primeval fireball. a) The angle subteneded by the horizon can be more or less than 1° if space is curved.
  50. 50. LSS 14 Gly horizon Critical density Universe Ω=1 1o horizon Ω>1 2o High density Universe horizon 0.5o Low density Universe Ω<1
  51. 51. PS PS PS 0 200 l 0 200 l 0 200 l High density Universe Critical density Universe Low density Universe Ω>1 Ω=1 Ω<1 2o 1o 0.5o
  52. 52. The quest for high resolution b) Within a causally connected region, the hot, ionized gas of the primeval fireball is subject to opposite forces: gravity and photon pressure. • If a density fluctuation is present, “acoustic oscillations” start, depending on the composition of the universe (density of baryons) and on the spectrum of initial density fluctuations.
  53. 53. Density perturbations (Δρ/ρ) were oscillating in the primeval plasma (as a result of the opposite effects of gravity and photon pressure). Due to gravity, T is reduced enough Δρ/ρ increases, that gravity wins again and so does T Pressure of photons overdensity increases, resisting to the compression, and the t perturbation bounces back Before recombination T > 3000 K t After recombination T < 3000 K Here photons are not tightly coupled to matter, and their pressure is not effective. Perturbations can grow and form Galaxies. After recombination, density perturbation can grow and create the hierarchy of structures we see in the nearby Universe.
  54. 54. • The study of solar oscillations allows us to study the interior structure of the sun, well below the photosphere, because these waves depend on the internal structure of the sun. • The study of CMB anisotropy allows us to study the universe well behind (well before) the cosmic photosphere (the recombination epoch), because the oscillations depend on the composition of the universe and on the initial perturbations.
  55. 55. How to obtain wide, high angular resolution maps of the CMB • Angular Resolution: Microwave telescope, at relatively high frequencies (θ=λ/D) • 150GHz: peak of CMB brightness • Low sky noise and high transparency at 150 GHz: Balloon or Satellite • High sensitivity at 150 GHz: cryogenic bolometers • Multiband for controlling foreground emission Statistical samples of the CMB sky (about one hundred directions) in the 90s In Italy: ARGO In the USA: MAX, MSAM, …
  56. 56. How to obtain wide, high angular resolution maps of the CMB • Angular Resolution: Microwave telescope, at relatively high frequencies (θ=λ/D) • 150GHz: peak of CMB brightness • Low sky noise and high transparency at 150 GHz: Balloon or Satellite • High sensitivity at 150 GHz: cryogenic bolometers • Multiband for controlling foreground emission • Sensitivity and sky coverage (size of explored region): either – Extremely high sensitivity (0.1K) and regular flight or – High sensitivity (0.3K) and long duration flight
  57. 57. How to obtain wide, high angular resolution maps of the CMB • Angular Resolution: Microwave telescope, at relatively high frequencies (θ=λ/D) • 150GHz: peak of CMB brightness • Low sky noise and high transparency at 150 GHz: Balloon or Satellite • High sensitivity at 150 GHz: cryogenic bolometers • Multiband for controlling foreground emission • Sensitivity and sky coverage (size of explored region): either – Extremely high sensitivity (0.1K) and regular flight MAXIMA or – High sensitivity (0.3K) and long duration flight BOOMERanG
  58. 58. Universita’ di Roma, La Sapienza: Cardiff University: P. Ade, P. Mauskopf P. de Bernardis, G. De Troia, A. Iacoangeli, IFAC-CNR: A. Boscaleri S. Masi, A. Melchiorri, L. Nati, F. Nati, F. INGV: G. Romeo, G. di Stefano Piacentini, G. Polenta, S. Ricciardi, P. Santini, M. IPAC: B. Crill, E. Hivon Veneziani CITA: D. Bond, S. Prunet, D. Pogosyan Case Western Reserve University: LBNL, UC Berkeley: J. Borrill J. Ruhl, T. Kisner, E. Torbet, T. Montroy Imperial College: A. Jaffe, C. Contaldi Caltech/JPL: U. Penn.: M. Tegmark, A. de Oliveira-Costa A. Lange, J. Bock, W. Jones, V. Hristov Universita’ di Roma, Tor Vergata: N. Vittorio, University of Toronto: G. de Gasperis, P. Natoli, P. Cabella B. Netterfield, C. MacTavish, E. Pascale BOOMERanG
  59. 59. the BOOMERanG ballon-borne telescope Sun Shield Solar Array Differential GPS Array Star Camera Cryostat and detectors Ground Shield Primary Mirror (1.3m) Sensitive at 90, 150, 240, 410 GHz
  60. 60. 120 mm 3He fridge D D 0.3K D D D D D Focal plane assembly BOOMERanG-LDB Appl.Opt 1.6K MultiBand 150 D = location of detectors Photometers 150 (150,240,410) preamps 90 90 4o on the sky
  61. 61. • The instrument is flown above the Earth atmosphere, at an altitude of 37 km, by means of a stratospheric balloon. • Long duration flights (LDB, 1-3 weeks) are performad by NASA-NSBF over Antarctica • BOOMERanG has been flown LDB two times: • From Dec.28, 1998 to Jan.8, 1999, for CMB anisotropy measurements • In 2003, from Jan.6 to Jan.20, for CMB polarization measurements (B2K).
  62. 62. 9/Jan/1999
  63. 63. BOOMERanG • 1998: BOOMERanG mapped the temperature fluctuations of the CMB at sub-horizon scales (<1O). • The signal was well above the noise: 2 indep. det. at 150 GHz
  64. 64. • 1998: BOOMERanG mapped the temperature fluctuations of the CMB at sub-horizon scales (<1O). • The rms signal has the CMB spectrum and does not fit any spectrum of foreground emission.
  65. 65. PS PS PS 0 200 l 0 200 l 0 200 l High density Universe Critical density Universe Low density Universe Ω>1 Ω=1 Ω<1 2o 1o 0.5o
  66. 66. Full power spectrum measurement from BOOMERanG (2002) -Geometry of the universe from location of first peak -Signature of inflation from amplitudes of 3 peaks and general slope
  67. 67. In the primeval plasma, photons/baryons density perturbations start to oscillate only when the sound horizon becomes larger than their linear size . Small wavelength perturbations oscillate faster than large ones. multipole The angle subtended depends on the geometry of space Size of sound horizon v v v LSS 2nd dip C R size of perturbation (wavelength/2) v v 450 C R 2nd peak v v C 1st dip v 380000 ly 220 C 1st peak 0y time 300000 y Big-bang recombination Power Spectrum
  68. 68. We can measure cosmological parameters with CMB ! Temperature Angular spectrum varies with Ωtot , Ωb , Ωc, Λ, τ, h, ns, …
  69. 69. “The perfect universe”
  70. 70. • Data consistent with flat Universe  • Baryon fraction agrees with BBN • With supernovae or LSS => Λ term
  71. 71. Normal Radiation Matter < 0.3% 4% Dark Matter 22% Dark Energy 74%
  72. 72. Did Inflation really happen ? • We do not know. Inflation has not been proven yet. It is, however, a mechanism able to produce primordial fluctuations with the right characteristics. • Four of the basic predictions of inflation have been proven: – existence of super-horizon fluctuations – gaussianity of the fluctuations – flatness of the universe – scale invariance of the density perturbations • One more remains to be proved: the stochastic background of gravitational waves produced during the inflation phase. • CMB can help in this – see below.
  73. 73. CMB polarization • CMB radiation is Thomson scattered at recombination. • If the local distribution of incoming radiation in the rest frame of the electron has a quadrupole moment, the scattered radiation acquires some degree of linear polarization. Last scatte ring surfa ce
  74. 74. y y -10ppm +10ppm - + x x + - + - - - y - + x - = e- at last scattering
  75. 75. If inflation really happened… • It stretched geometry of OK space to nearly Euclidean • It produced a nearly scale invariant spectrum of density OK fluctuations • It produced a stochastic background of gravitational waves. ?
  76. 76. Quadrupole from P.G.W. • If inflation really happened: It stretched geometry of space to nearly Euclidean It produced a nearly scale invariant spectrum of gaussian density fluctuations It produced a stochastic background of gravitational waves: Primordial G.W. The background is so faint that even LISA will not be able to measure it. E-modes • Tensor perturbations also produce quadrupole anisotropy. They generate irrotational (E-modes) and rotational (B-modes) components in the CMB polarization field. • Since B-modes are not produced by scalar fluctuations, they represent a signature of inflation. B-modes
  77. 77. B-modes from P.G.W. • The amplitude of this effect is very small, but depends on the Energy scale of inflation. In fact the amplitude of tensor modes normalized to the scalar ones is: 1/ 4 ⎛ C2 ⎞ Inflation potential 1/ 4 GW ⎛ T⎞ V 1/ 4 ⎜ ⎟ ≡ ⎜ Scalar ⎟ ⎜C ⎟ ≅ ⎝S⎠ ⎝ 2 ⎠ 3.7 ×1016 GeV • and l(l + 1) B ⎡ V 1/ 4 ⎤ cl max ≅ 0.1μK ⎢ ⎥ 2π ⎢ 2 ×10 GeV ⎥ ⎣ 16 ⎦ • There are theoretical arguments to expect that the energy scale of inflation is close to the scale of GUT i.e. around 1016 GeV. • The current upper limit on anisotropy at large scales gives T/S<0.5 (at 2σ) • A competing effect is lensing of E-modes, which is important at large multipoles.
  78. 78. 06/01/2003
  79. 79. PSB devices & feed optics (Caltech + JPL) PSB Pair
  80. 80. 145 GHz T map (Masi et al., 2005) the deepest CMB map ever [Masi et al. 2005]
  81. 81. B03 TT Power Spectrum • Detection of anisotropy signals all the way up to l=1500 • Time and detector jacknife tests OK • Systematic effects negligible wrt noise & cosmic variance Jones et al. 2005
  82. 82. 19/20 La mappa dell’ universo primordiale con sovrapposta la polarizzazione Realizzata dal gruppo di Cosmologia di Tor Vergata (Genn. 2005)
  83. 83. TE Power Spectrum • Smaller signal, but detection evident (3.5σ) • NA and IT results consistent • Error bars dominated by cosmic variance • Time and detectors Piacentini et al. 2005 jacknife OK, i.e. systematics negligible • Data consistent with TT best fit model
  84. 84. EE Power Spectrum • Signal extremely small, but detection evident for EE (non zero at 4.8σ). • No detection for BB nor for EB • Time and detectors jacknife OK, i.e. systematics negligible • Data consistent with TT best Montroy et al. 2005 fit model • Error bars dominated by detector noise. Montroy et al. 2005
  85. 85. WMAP (2002) Wilkinson Microwave Anisotropy Probe
  86. 86. WMAP in L2 : sun, earth, moon are all well behind the solar shield.
  87. 87. WMAP Hinshaw et al. 2006 astro-ph/0603451 Detailed Views of the 1o Recombination Epoch (z=1088, 13.7 Gyrs ago) BOOMERanG Masi et al. 2005 astro-ph/0507509
  88. 88. 2006 Hinshaw et al. 2006
  89. 89. Paradigm of CMB anisotropies Power spectrum k l smaller than Power Processed by of CMB causal effects like spectrum of temperature horizon Acoustic oscillations Scales perturbations Radiation pressure fluctuations Gaussian, from photons resists gravitational INFLATION adiabatic Quantum (density) compression fluctuations horizon horizon horizon in the early Universe (ΔT/T) = (Δρ/ρ) /3 + (Δφ/c2)/3 P(k)=Akn l( l+1) cl – (v/c)•n larger than horizon Scales Unperturbed plasma neutral 0 10-36s 3 min 300000 yrs Big-Bang Inflation Nucleosynthesis Recombination t
  90. 90. Need for high angular resolution < 10’ 2006 Hinshaw et al. 2006
  91. 91. Cosmological Parameters Assume an adiabatic inflationary model, and compare with same weak prior on 0.5<h<0.9 WMAP BOOMERanG (100% of the sky, <1% gain (4% of the sky, 10% gain calibration, <1% beam, calibration, 10% beam, multipole coverage 2-700) multipole coverage 50- 1000) Bennett et al. 2003 Ruhl et al. astro-ph/0212229 • Ωο =1.02+0.02 • Ωο = 1.03+0.05 • ns = 0.99+0.04 * • ns = 1.02+0.07 • Ωbh2 =0.022+0.001 • Ωbh2 =0.023+0.003 • Ωmh2 =0.14+0.02 • Ωmh2 =0.14+0.04 • T = 13.7+0.2 Gyr • T=14.5+1.5 Gyr • τrec= ? • τrec= 0.166+0.076
  92. 92. 2009 Planck is a very ambitious experiment. It carries a complex CMB experiment (the state of the art, a few years ago) all the way to L2, improving the sensitivity wrt WMAP by at least a factor 10, extending the frequency coverage towards high frequencies by a factor about 10
  93. 93. PLANCK ESA’s mission to map the Cosmic Microwave Background Image of the whole sky at wavelengths near the intensity peak of the CMB radiation, with • high instrument sensitivity (ΔT/T∼10-6) • high resolution (≈5 arcmin) • wide frequency coverage (25 GHz-950 GHz) • high control of systematics •Sensitivity to polarization Launch: 2009; payload module: 2 instruments + telescope • Low Frequency Instrument (LFI, uses HEMTs) • High Frequency Instrument (HFI, uses bolometers) • Telescope: primary (1.50x1.89 m ellipsoid)
  94. 94. Galaxy CMB
  95. 95. Galaxy CMB
  96. 96. Galaxy CMB
  97. 97. Two Instruments: Low Frequency (LFI) and High Frequency (HFI)
  98. 98. Spider Web and PSB Bolometers • Ultra-sensitive Technology • Tested on BOOMERanG (Piacentini et al. 2002, Crill et al. 2004, Masi et al. 2006) for bolometers, filters, horns, scan at 0.3K and on Archeops at 0.1K (Benoit et al. 2004). • Crucial role of balloon missions to get important science results, but also to validate satellite technology.
  99. 99. Measured performance of Planck HFI bolometers (0.1K) (Holmes et al., Appl. Optics, 47, 5997, 2008) Multi-moded = Photon noise limit
  100. 100. Planck-Herschel Launch May 14, 2009 15:12 CEST
  101. 101. Telescopio fuori asse, diametro specchio principale 1.8 m
  102. 102. Observing strategy The payload will work from L2, to avoid the emission of the Earth, of the Moon, of the Sun Boresight (85o from spin axis) Field of view rotates at 1 rpm M Ecliptic plane 1 o/day E L2
  103. 103. Launch May 14th, 2009 Cruise May-June 2009 Calibrations, Scan start July 2009
  104. 104. HFI Verification / Calibration Plan e plan s tem cal ht -sy FI fo SL) -flig b H su C in S, Main beam (IA LIGH, BEAM Far side lobes LIGH, BEAM Spectral response Time response LFER, SPIN Optical polarisation LIGH, POLC Thermo-optical coupling, bckgnd 01TO, 16TO, 4KTO Linearity 4KTO Absolute response LIGH Detection noise RW72, SPIN, NOIS Crosstalk XTLK Detection chain caract QECn, IVCF, IBTU, PHTU Numerical compression CPSE, CPVA Cryo chain setup 4KTU,16TU, 01TU Compatibility XTRA, NOIS Scanning ACMS [1.7arcmin] Solar AA SUNI [50%]
  105. 105. 3 months after launch ● The launch was flawless and the transfer to final orbit was completed on 1 July ● All parts of the satellite survived launch and it is fully functional ● Coldest temperature (0.1 K) was reached on 3 July. The thermal behavior (static and dynamic) is as predicted from the ground. ● The instruments have been fully tuned and are in stable operations since 30 July ● All planned initial tests and measurements have been completed on 13 August ● Planck is now transitioning into routine operational mode Preview of data from the first-light survey (2 weeks of stable operation)
  106. 106. The sky explored by Planck so far (First Light Survey, 2 weeks)
  107. 107. The sky explored by Planck so far (First Light Survey, 2 weeks) Galactic Plane
  108. 108. The sky explored by Planck in the First Light Survey, first 2 weeks High Galactic Latitude (CMB)
  109. 109. After Planck • Planck will do many things but will not do: – Accurate measurement of B-Modes (gravitational waves from inflation) through polarization (unless we are very lucky …) – Measurements at high angular resolution – Deep surveys of clusters and superclusters of galaxies for SZ effect
  110. 110. precision CMB measurements High Resolution Polarization Anisotropy λ-spectrum of the CMB and its anisotropy •Damping tail & param.s • Inflation • SZ & Clusters • SZ distortions • Reionization • Early Metals • nature of dark matter • Recombination lines • Magnetic fields • CII • neutrino physics •… • ….. •…..
  111. 111. After Planck: CMB arrays • Once we get to the photon noise limit, the only way to improve the measurement is to improve the mapping speed, i.e. to produce large detector arrays. • The most important characteristic of future CMB detectors, in addition to be CMB noise limited, is the possibility to replicate detectors in large arrays at a reasonable cost. • Suitable detection methods: – TES bolometers arrays – Direct detection and KIDs arrays
  112. 112. Bolometer Arrays • Once bolometers reach BLIP conditions (CMB BLIP), the mapping speed can only be increased by creating large bolometer arrays. • BOLOCAM and MAMBO are examples of large arrays with hybrid components (Si Bolocam Wafer (CSO) wafer + Ge sensors) • Techniques to build fully litographed arrays for the CMB are being developed. • TES offer the natural sensors. (A. Lee, D. Benford, A. Golding, F. Gatti …) MAMBO (MPIfR for IRAM)
  113. 113. Now
  114. 114. 295 bolometers LABOCA (345 GHz) Bonn APEX 12m telescope Atacama (ALMA site) 330 bolometers APEX-SZ (150 GHz) Berkeley
  115. 115. Effect of a signal transmitted through the feed line past the resonator: Attenuation ≈ 0dB phase amplitude Which are the effects of incoming radiation? T<Tc • nQP Rs QP • nCP Lkin n′CP< nCP Zs changes CP hν >2DE Claudia Giordano
  116. 116. KIDs testbench: cryogenic system and RF circuit KID SS-SS coax 300mK 1xDC block 1xDC block 1x10dB atten 2K SCN-CN coax 2xDC block 2xDC block 2x10dB atten SCN-CN coax 30K 36mm 300K 3x10dB atten amplifiers bias generator and Cryostat modified acquisition data system to have RF ports VNA : slower, easier, can give information on the sanity of the whole circuit. Ideal for the first runs. IQ mixers: faster, essential to measure noise, QP lifetime... Need fast acquisition system
  117. 117. Array of 81 LKID built by the RIC (INFN gruppo V) collaboration (Dip. Fisica La Sapienza, FBK Trento, Dip. Fis. Perugia
  118. 118. July 1st, 2009 First large balloon From Svalbards
  119. 119. • European proposal recently B-Pol submitted to ESA (Cosmic Vision). (www.b-pol.org) • ESA encourages the development of technology and resubmission for next round • Detector Arrays development activities (KIDs in Rome, TES in Oxford, Genova etc.) • A balloon-borne payload being developed with ASI (B-B-Pol).
  120. 120. Sensitivity and frequency coverage: the focal plane • Baseline technology: TES bolometers arrays Corrugated feedhorns Sub-K, 600 mm for polarization purity and beam symmetry
  121. 121. .. Ancora moltissimo da fare Vedi anche: PdB - Osservare l’ Universo - Il Mulino (da Aprile)
  122. 122. Per saperne di più… • Steven Weinberg “I primi tre minuti”, Oscar Mondadori (Milano, 1986). • Italo Mazzitelli “Tutti gli universi possibili e altri ancora”, Liguori Editore (Napoli, 2002), • Paolo de Bernardis “Osservare l’ Universo”, Il Mulino (Bologna, da Aprile 2010).

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