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

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. 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. 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. Lunghezza d’ onda λ (nm)
Galassia
molto lontana
Galassia lontana
Galassia vicina
laboratorio
Ca II HI
Mg I Na I

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. • 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. • 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. 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. 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. 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. Strong evidence for a hot
early phase of the Universe
Thermal spectrum ….
… and accurate isotropy
0K 3K 5K
Cosmic
Microwave
Background

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. 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. 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. 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. 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. Circa 1970
Circa 1980

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. 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. 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. 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. 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. 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. σ (cm-1) wavenumber

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. • Techniques ?
RJ Wien
ν << ν max = 160 GHz ⇒ coherent detectors
ν >> ν max = 160 GHz ⇒ bolometers
ν ≈ ν max = 160 GHz ⇒ ? ??

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. 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. 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. 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. 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. 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. 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. 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. 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. 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. 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. Granulazione solare
Gas incandescente
sulla superficie del
Sole (5500 K)
8 minuti luce
Qui, ora

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. 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. a(t)
g
ig B an
B
the
ter
s af
Cosmic distances
1 n
nsity,
l de
Cr itica
Billion years t

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. 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. 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. 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. • 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. θ d
R
d ao 380000 ly
θ≈ × ≈ ×1100 ≈1o
R a 14000000000 ly

48. 380000 lyrs
R
1o
COBE resolution
Here, now
K
10o
000
ang
∞)
T=3
BigB
(T=
R= distance
from us
= 14 Glyrs

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. 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. 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. 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. 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. • 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. 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. 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. 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. 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. 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. 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. • 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. 9/Jan/1999

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. • 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. 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

67. 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

68. 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

69. We can measure cosmological parameters with CMB !
Temperature Angular spectrum varies with Ωtot , Ωb , Ωc, Λ, τ, h, ns, …

70. “The perfect universe”

71. • Data consistent with flat Universe
• Baryon fraction agrees with BBN
• With supernovae or LSS => Λ term

72. Normal
Radiation Matter
< 0.3% 4%
Dark
Matter
22%
Dark
Energy
74%

73. 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.

74. 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

75. y y
-10ppm +10ppm
- +
x x
+ - + - - -
y
- +
x
-
= e- at last scattering

76. 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.
?

77. 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

78. 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.

79. 06/01/2003

80. PSB devices & feed optics (Caltech + JPL)
PSB Pair

81. 145 GHz
T map
(Masi et al.,
2005)
the deepest
CMB map
ever
[Masi et al. 2005]

82. 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

83. 19/20
La mappa dell’ universo primordiale con sovrapposta la polarizzazione
Realizzata dal gruppo di Cosmologia di Tor Vergata (Genn. 2005)

84. 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

85. 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

86. WMAP (2002)
Wilkinson Microwave Anisotropy Probe

87. WMAP in L2 : sun, earth, moon are all
well behind the solar shield.

88. 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

89. 2006 Hinshaw et al. 2006

90. 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

91. Need for high
angular
resolution
< 10’
2006 Hinshaw et al. 2006

92. 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

93. 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

94. 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)

96. Galaxy
CMB

97. Galaxy
CMB

98. Galaxy
CMB

99. Two Instruments: Low Frequency (LFI) and High Frequency (HFI)

102. 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.

103. Measured performance of Planck HFI bolometers (0.1K)
(Holmes et al., Appl. Optics, 47, 5997, 2008)
Multi-moded
=
Photon
noise
limit

104. Planck-Herschel
Launch
May 14, 2009
15:12 CEST

105. Telescopio fuori
asse, diametro
specchio principale
1.8 m

109. 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

110. Launch
May 14th, 2009
Cruise
May-June 2009
Calibrations,
Scan
start July 2009

112. 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%]

113. 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)

114. The sky explored by Planck so far (First Light Survey, 2 weeks)

115. The sky explored by Planck so far (First Light Survey, 2 weeks)
Galactic Plane

125. The sky explored by Planck in the First Light Survey, first 2 weeks
High Galactic Latitude (CMB)

130. 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

131. 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
•… • …..
•…..

132. 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

133. 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)

135. Now

136. 295 bolometers LABOCA (345 GHz) Bonn
APEX 12m telescope
Atacama (ALMA site)
330 bolometers APEX-SZ (150 GHz) Berkeley

137. 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

138. 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

139. Array of 81 LKID
built by the RIC (INFN gruppo V) collaboration
(Dip. Fisica La Sapienza, FBK Trento, Dip. Fis. Perugia

140. July 1st, 2009
First large balloon
From Svalbards

141. • 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).

142. Sensitivity and frequency coverage: the focal plane
• Baseline technology: TES bolometers arrays
Corrugated feedhorns Sub-K, 600 mm
for polarization purity and
beam symmetry

143. .. Ancora moltissimo da fare
Vedi anche: PdB - Osservare l’ Universo - Il Mulino (da Aprile)

144. 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).