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

1. L’ orizzonte in cosmologia
Oltre l’ orizzonte cosmologico
Paolo de Bernardis
Dipartimento di Fisica
Università di Roma La Sapienza
• L’ orizzonte delle particelle è la superficie che ci separa da
A pranzo con la fisica - NIPS Lab quanto non possiamo osservare, perché la luce partita oltre l’
Dipartimento di Fisica Università di Perugia orizzonte non è ancora arrivata fino a noi. Le particelle che si
trovano oltre l’ orizzonte non sono ancora in contatto causale
11/03/2010 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.
Lunghezza d’ onda λ (nm)
Il redshift
• Negli anni ’20 Carl Wirtz, Galassia
Edwin Hubble ed altri, molto lontana
analizzarono la luce
proveniente da galassie
distanti, e notarono che piu’ Galassia lontana
una galassia e’ distante,
piu’ le lunghezze d’ onda
della sua luce sono Galassia vicina
allungate (spostamento
verso il rosso, redshift).
laboratorio
•Questo dato empirico viene
interpretato come una prova
dell’ espansione dell’
Ca II HI
universo.
Mg I Na I
Percorrendo distanze cosmologiche, la luce cambia colore
• Se vogliamo arrivare a
• La relativita’ generale di Einstein prevede
che, in un universo in espansione, le osservare l’ orizzonte,
lunghezze d’onda λ dei fotoni si allunghino dobbiamo osservare più
esattamente quanto le altre lunghezze. lontano possibile.
• Piu’ distante e’ una galassia, piu’ e’ lungo il
cammino che la luce deve percorrere, piu’ • La luce che è partita da
lungo e’ il tempo che impiega, maggiore e’ regioni di universo così
l’ espansione dell’ universo dal momento remote, avrà allungato
dell’ emissione a quello dalla ricezione, e
piu’ la lunghezza d’ onda viene allungata. moltissimo le sue
lunghezze d’ onda,
to diventando infrarossa, o
microonde, o radioonde …
t1 • Quindi richiede telescopi e
rivelatori speciali per essere
osservata.
t2
1

2. • L’ orizzonte a cui si arriva, però, è di tipo fisico. Orizzonte fisico
• Infatti l’ espansione dell’ universo comporta un suo • In un universo in espansione, dominato dalla
raffreddamento. Osservando lontano riceveremo radiazione, si può calcolare accuratamente il
luce che è stata emessa quando l’ universo era più tempo necessario per passare dal Big Bang
caldo di oggi. (densità e temperatura infinite) fino alla
• Se guardiamo abbastanza lontano, arriveremo ad temperatura in cui elettroni e protoni
osservare epoche in cui l’ universo era caldo come possono combinarsi in atomi
(ricombinazione dell’ idrogeno).
o più della superficie del sole.
• La temperatura a cui avviene la
• E quindi era ionizzato. In quell’ epoca i fotoni non ricombinazione è circa 3000K, e il tempo
potevano propagarsi su linee rette, ma su spezzate necessario per arrivarci è di 380000 anni.
venendo continuamente diffusi dagli elettroni liberi • Quindi per i primi 380000 anni della sua
del mezzo ionizzato. evoluzione l’ universo è ionizzato e opaco.
• L’ universo primordiale è opaco, come opaco è l’
interno di una stella.
Orizzonte fisico Composizione della luce che viene dal sole (spettro)
Lunghezza d’ onda (micron)
• Osservando sempre più lontano,
potremo vedere solo finchè l’ universo è Intensità luminosa W/m2/sr/cm-1) Radiazione Termica,
trasparente. Cioè fino all’ epoca della Spettro di Corpo Nero
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.
Strong evidence for a hot
early phase of the Universe
Orizzonte fisico
• Nel seguito:
Thermal spectrum ….
–L’ osservazione della superficie di
… and accurate isotropy
ultimo scattering.
• Come si fa
0K 3K 5K • Quali sono i risultati
• Orizzonti causali impressi nell’ orizzonte
fisico
• Conseguenze per la cosmologia e la
Cosmic fisica fondamentale
Microwave –Come andare oltre.
Background
2

3. How to detect CMB photons How to detect CMB photons
• E(γCMB) of the order of 1 meV • E(γCMB) of the order of 1 meV
• Frequency: 15-600 GHz • Frequency: 15-600 GHz
• Detection methods: • Detection methods:
– Coherent (antenna + amplifier) – Coherent (antenna + amplifier)
– Thermal (bolometers) – Thermal (bolometers)
– Direct (Cooper pairs in KIDs) – Direct (Cooper pairs in KIDs)
• Space (atmospheric opacity) • Space (atmospheric opacity)
Cryogenic Bolometers Cryogenic Bolometers Again, need
• The CMB spectrum is a continuum and bolometers are wide band
• Johnson noise in the thermistor of low
detectors. That’s why they are so sensitive. temperature
d Δ V J2 and low
Thermometer = 4 kTR
(Ge thermistor (ΔR) df background
Load resistor
at low T) • Temperature noise
d Δ W T2 4 kT 2 G eff
= 2
df G eff + (2π fC )
2
Incoming Q
ΔV Photons (ΔB) • Photon noise
d ΔWPh 4k 5TBG x4 (ex −1+ ε )
2 5
Feed = 2 3 ∫ε dx
Integrating Horn filter df ch (ex −1)2
Radiation cavity (angle selective)
(frequency • Total NEP (fundamental):
Absorber (ΔT) selective)
1 d ΔVJ d ΔWT d ΔWPh
2 2 2
• Fundamental noise sources are Johnson noise in the thermistor
(<ΔV2> = 4kTRΔf), temperature fluctuations in the thermistor NEP2 = + +
((<ΔW2> = 4kGT2Δf), background radiation noise (Tbkg5) need ℜ2 df df df
to reduce the temperature of the detector and the radiative
background.
•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.
Circa 1970 Also, the heat capacity is
reduced by a large factor
with respect to the solid
absorber.
Circa 1980 •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
3

4. Development of thermal detectors for far IR and mm-waves
17
10
How to detect CMB photons
Langley's bolometer
Golay Cell
a measurement (seconds)
12 • E(γCMB) of the order of 1 meV
10 Golay Cell
time required to make
Boyle and Rodgers bolometer • Frequency: 15-600 GHz
1year F.J.Low's cryogenic bolometer • Detection methods:
7
10 Composite bolometer
1day – Coherent (antenna + amplifier)
1 hour Composite bolometer at 0.3K
– Thermal (bolometers)
2
10 – Direct (Cooper pairs in KIDs)
1 second
Spider web bolometer at 0.3K
Spider web bolometer at 0.1K
Photon noise limit for the CMB
• Space (atmospheric opacity)
1900 1920 1940 1960 1980 2000 2020 2040 2060
year
COBE-FIRAS MPI
• COBE-FIRAS was a (Martin Puplett
cryogenic Martin- Interferometer)
Puplett Fourier- Beamsplitter =
Transform wire grid
polarizer
Spectrometer with
composite Differential
bolometers. It was instrument
placed in a 400 km
orbit.
• A zero instrument ∞
I SKY ( x) = C ∫ [SSKY (σ ) − SREF (σ )]rt(σ ){ + cos[4πσx]}dσ
1
comparing the specific
sky brightness to the
0
∞
brightness of a ICAL( x) = C∫ [SCAL(σ ) − SREF (σ )]rt(σ ){ + cos[4πσx]}dσ
1
cryogenic Blackbody 0
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. σ (cm-1) wavenumber
4

5. • The spectrum • Techniques ?
2h ν 3
B(ν , T ) =
c2 ex −1
TCMB = 2.725K
RJ Wien RJ Wien
hν ν
xCMB = ≅
kTCMB 56 GHz
xmax
1 − e − xmax = ⇒ xmax = 2.82 ⇒
3
ν << ν max = 160 GHz ⇒ coherent detectors
ν max = 159 GHz (σ max = 5.31 cm −1 )
ν >> ν max = 160 GHz ⇒ bolometers
λ
B(ν , T ) = B(λ , T ) ⇒ λmax = 1.06 mm ν ≈ ν max = 160 GHz ⇒ ? ??
ν
• The DMR instrument aboard
of the COBE satellite
COBE-DMR
CMB anisotropy
Cosmic Horizons
measured the first map of • The very good isotropy of the CMB sky is to
CMB anisotropy (1992) some extent surprising.
Galactic Plane
• The contrast of the image is
very low, but there are
• The CMB comes from an epoch of 380000 years
structures, at a level of after the Big Bang.
10ppm. • So it depicts a region of the universe as it was
• Instrumental noise is 380000 years after the Big Bang.
significant in the maps
(compare the three different
• The region we can map, however, is much wider
wavelengths) than 380000 light years.
• DMR did not have a real • So it contains subregions which are separated
telescope, so the angular more than the length light has travelled since the
resolution was quite coarse Big Bang. These regions would not be in causal
(10 o !!) contact in a static universe.
R= distance from R= distance from
us = 14 Glyrs a l Gly us = 14 Glyrs
s ev er
y
4 Gl
But also distance in But also distance in
R=1
R time: 14 Gyrs ago R= time: 14 Gyrs ago
& 14
t Gl
y
here, now here, now
K
K
000
000
T=3
T=3
Transparent Transparent
universe universe
Opaque Opaque
universe universe
5

6. Cosmic Horizons
r=3 R= distance from
80 k
l y
ly us = 14 Glyrs
er al G
ly
s ev
0k
• We measure the same brightness
y
38
4 Gl
But also distance in
r=
(temperature) in all these regions, and this
R=1
R= time: 14 Gyrs ago
14
Gl
is surprising, because to attain thermal
y equilibrium, contact is required ! (through
forces, thermal, radiative …).
here, now • We live in an expanding universe. Regions
K
separated by more than 380000 light
000
T=3 years might have been in causal contact
Transparent
Opaque
universe (and thus homogeneized) earlier.
universe
Expansion vs Horizon Expansion vs Horizon
In a Universe made of on In a Universe made of on
r iz r iz
matter and radiation, the
e ho matter and radiation, the
e ho
expansion rate decreases f th expansion rate decreases f th
with time. eo with time. eo
s iz s iz
size of size of
ed region ed region
the consider the consider
So a region as large as
the horizon when the CMB
is released ….
380000 y
time time
Expansion vs Horizon Expansion vs Horizon
In a Universe made of on In a Universe made of on
r iz r iz
matter and radiation, the
e ho matter and radiation, the
e ho
expansion rate decreases f th expansion rate decreases f th
with time. eo with time. eo
s iz s iz
size of size of
ed region ed region
the consider the consider
… has never been … nor has been
causally connected causally connected to
before surrounding regions
380000 y 380000 y
time time
6

7. Cosmic Horizons Granulazione solare
• Hence the “Paradox of Horizons” : Gas incandescente
sulla superficie del
• We see approximately the same temperature Sole (5500 K)
everywhere in the map of the CMB, but we 8 minuti luce
Qui, ora
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 ?
Granulazione solare Flatness Paradox
Gas incandescente • The expansion of the Universe is regulated by the
sulla superficie del Friedmann equation, directly deriving from
Sole (5500 K)
Einstein’s equations for a homogeneous and
Qui, ora
8 minuti luce isotropic fluid.
• If the Universe contains only matter and radiation, it
either collapses or dilutes, with a rate depending on
Gas incandescente
the mass-energy density.
nell’ universo
primordiale (l’
• To get an evolution with a mass-energy density of
universo diventa the order of the observed one today, billions of
trasparente a 3000 K)
years after the Big Bang, you need to tune it at the
Qui, ora
14 miliardi di anni luce beginning very accurately, precisely equal to a
critical value.
Mappa di BOOMERanG dell’ Universo Primordiale
• How was this fine-tuning achieved ?
Inflation might be the solution
a(t) C
I n os m
fla ic
tio
n
Sub-atomic scales
ang
ig B
th eB
ter t=10-36s
s af
Cosmic distances
1n
ity,
Quantum fluctuations of
ens
ic al d the field dominating the
Crit 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
Billion years t the first split-second density fluctuations
7

8. ma
l size of
d region
Expansion vs Horizon nor lution the considere
e vo
According to the inflation on on
r iz r iz
theory ….
e ho e ho
f th f th
eo eo
s iz s iz
exponential
size of
expansion
ed region
the consider
Inflation:
A region as large as the
horizon when the CMB is
released ….
…had been causally
connected to the
surrounding regions
before inflation
380000 y 10-36 s
time time
ma
l size of
d region • Inflation
nor lution the considere – Provides a physical process to origin density fluctuations
e vo
– Explains the flatness paradox
– Explains the horizons paradox
on
r iz • Is a predictive theory (a list of > models has been compiled..)
e ho
f th – Predicts gaussian density fluctuations
eo – Predicts scale invariant density fluctuations
s iz
– Predicts Ω=1
exponential
• How can we test it ?
expansion
Inflation:
• 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
Here the horizon
imprinted in the image of the CMB.
contains all of the • The angular size subtended by the horizons when the CMB is
universe observable released is around 1 degree, if the geometry of space is
today Euclidean.
• We need sharp images of the CMB, so that we can resolve
10-36 s time the density fuctuations predicted by inflation.
380000 lyrs
R
θ d
1o
R COBE resolution
Here, now
K
10o
000
(T= ng
∞)
a
BigB
T=3
d ao 380000 ly
θ≈ × ≈ ×1100 ≈1o
R a 14000000000 ly
R= distance
from us
= 14 Glyrs
8

9. LSS
high resolution 14 Gly
horizon
• The images from COBE-DMR were not sharp Critical density Universe Ω=1
enough to resolve cosmic horizons (the angular 1o
resolution was 7°).
• After COBE, experimentalists worked hard to
develop higher resolution experiments.
• In addition to testing inflation, we expected high
horizon
resolution observations to give informations Ω>1
about 2o
High density Universe
a) The geometry of space
b) The physics of the primeval fireball.
horizon
a) The angle subteneded by the horizon can be 0.5o
more or less than 1° if space is curved. Low density Universe Ω<1
PS PS PS
The quest for high resolution
0 200
High density Universe
l 0 200
Critical density Universe
l 0 200
Low density Universe
l b) Within a causally connected region, the
Ω>1 Ω=1 Ω<1 hot, ionized gas of the primeval fireball is
subject to opposite forces: gravity and
photon pressure.
2o 1o • If a density fluctuation is present,
0.5o “acoustic oscillations” start, depending on
the composition of the universe (density
of baryons) and on the spectrum of initial
density fluctuations.
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
• The study of solar oscillations
and so does T allows us to study the interior
structure of the sun, well below
the photosphere, because these
waves depend on the internal
Pressure of photons structure of the sun.
overdensity increases, resisting to the
compression, and the
t perturbation bounces back • The study of CMB anisotropy
Before recombination T > 3000 K allows us to study the universe
t After recombination T < 3000 K well behind (well before) the
cosmic photosphere (the
Here photons are not tightly recombination epoch), because
coupled to matter, and their the oscillations depend on the
pressure is not effective. composition of the universe
Perturbations can grow and
form Galaxies.
and on the initial perturbations.
After recombination, density perturbation can grow and create the hierarchy of structures
we see in the nearby Universe.
9

10. How to obtain wide, high angular How to obtain wide, high angular
resolution maps of the CMB resolution maps of the CMB
• Angular Resolution: Microwave telescope, at • Angular Resolution: Microwave telescope, at
relatively high frequencies (θ=λ/D) relatively high frequencies (θ=λ/D)
• 150GHz: peak of CMB brightness • 150GHz: peak of CMB brightness
• Low sky noise and high transparency at 150 GHz: • Low sky noise and high transparency at 150 GHz:
Balloon or Satellite Balloon or Satellite
• High sensitivity at 150 GHz: cryogenic bolometers • High sensitivity at 150 GHz: cryogenic bolometers
• Multiband for controlling foreground emission • Multiband for controlling foreground emission
• Sensitivity and sky coverage (size of explored
Statistical samples of the CMB sky (about one hundred directions) in the 90s region): either
– Extremely high sensitivity (0.1K) and regular flight
In Italy: ARGO In the USA: MAX, MSAM, … or
– High sensitivity (0.3K) and long duration flight
How to obtain wide, high angular
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
resolution maps of the CMB Piacentini, G. Polenta, S. Ricciardi, P. Santini, M.
Veneziani
IPAC: B. Crill, E. Hivon
CITA: D. Bond, S. Prunet, D. Pogosyan
Case Western Reserve University:
• Angular Resolution: Microwave telescope, at J. Ruhl, T. Kisner, E. Torbet, T. Montroy
LBNL, UC Berkeley: J. Borrill
Imperial College: A. Jaffe, C. Contaldi
relatively high frequencies (θ=λ/D) Caltech/JPL:
A. Lange, J. Bock, W. Jones, V. Hristov
U. Penn.: M. Tegmark, A. de Oliveira-Costa
Universita’ di Roma, Tor Vergata: N. Vittorio,
• 150GHz: peak of CMB brightness University of Toronto:
B. Netterfield, C. MacTavish, E. Pascale
G. de Gasperis, P. Natoli, P. Cabella
• 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
BOOMERanG
the BOOMERanG ballon-borne telescope 120 mm
3He
Sun Shield fridge
Solar
Array Differential
GPS Array D D
Star
Camera
Cryostat
and 0.3K
detectors
D D D D
D Focal plane assembly
Ground BOOMERanG-LDB Appl.Opt
Shield Primary 1.6K MultiBand
Mirror 150 D = location of detectors
Photometers 150
(150,240,410)
(1.3m)
preamps 90 90
4o on the sky
Sensitive at 90, 150, 240, 410 GHz
10

11. • The instrument is flown 9/Jan/1999
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).
BOOMERanG
• 1998: • 1998:
BOOMERanG BOOMERanG
mapped the mapped the
temperature temperature
fluctuations of fluctuations of
the CMB at the CMB at
sub-horizon sub-horizon
scales (<1O). scales (<1O).
• The signal • The rms
was well signal has the
above the CMB
noise: spectrum and
does not fit
2 indep. det.
at 150 GHz any spectrum
of foreground
emission.
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
11

12. 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.
Full power
multipole
The angle subtended depends on the geometry of space
spectrum Size of sound horizon
v v v LSS
measurement 2nd dip
from C R
BOOMERanG size of perturbation
(2002) (wavelength/2) v v
450
-Geometry of C R 2nd peak
the universe
from location of v v
first peak
C
1st dip
-Signature of v 380000 ly
inflation from
amplitudes of 3
220
C 1st peak
peaks and
general slope 0y time 300000 y
Big-bang recombination Power Spectrum
We can measure cosmological parameters with CMB !
Temperature Angular spectrum varies with Ωtot , Ωb , Ωc, Λ, τ, h, ns, … “The perfect universe”
• Data consistent with flat Universe Radiation
Normal
Matter
• Baryon fraction agrees with BBN < 0.3% 4%
• With supernovae or LSS => Λ term
Dark
Matter
22%
Dark
Energy
74%
12

13. Did Inflation really happen ? CMB polarization
• We do not know. Inflation has not been • CMB radiation is Thomson scattered at recombination.
proven yet. It is, however, a mechanism able • If the local distribution of incoming radiation in the
to produce primordial fluctuations with the right rest frame of the electron has a quadrupole moment,
characteristics. the scattered radiation acquires some degree of linear
polarization.
• Four of the basic predictions of inflation have
been proven: Last scatte
ri ng surface
– 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.
y y
-
-10ppm +10ppm
+ If inflation really
happened…
x x
+ - + - - - • It stretched geometry of OK
space to nearly Euclidean
y
- + • It produced a nearly scale
invariant spectrum of density OK
fluctuations
x
- • It produced a stochastic
background of gravitational
waves.
?
= e- at last scattering
Quadrupole from P.G.W. B-modes from P.G.W.
• If inflation really happened: • The amplitude of this effect is very small, but
It stretched geometry of space to depends on the Energy scale of inflation. In fact the
nearly Euclidean amplitude of tensor modes normalized to the scalar
It produced a nearly scale invariant ones is:
1/ 4
spectrum of gaussian density 1/ 4
⎛ C2 ⎞
GW
Inflation potential
⎛T ⎞ V 1/ 4
fluctuations ⎜ ⎟ ≡ ⎜ Scalar ⎟
⎜C ⎟ ≅
It produced a stochastic background of ⎝S⎠ ⎝ 2 ⎠ 3.7 × 1016 GeV
gravitational waves: Primordial G.W. • and
l(l + 1) B ⎡ V 1/ 4 ⎤
The background is so faint that even
E-modes cl max ≅ 0.1μK ⎢ ⎥
LISA will not be able to measure it. 2π ⎢
⎣ 2 ×1016 GeV ⎥
⎦
• Tensor perturbations also produce
• There are theoretical arguments to expect that the
quadrupole anisotropy. They generate
energy scale of inflation is close to the scale of GUT
irrotational (E-modes) and rotational
(B-modes) components in the CMB
i.e. around 1016 GeV.
polarization field. • The current upper limit on anisotropy at large scales
• Since B-modes are not produced by scalar gives T/S<0.5 (at 2σ)
fluctuations, they represent a signature of • A competing effect is lensing of E-modes, which is
inflation. B-modes important at large multipoles.
13

14. PSB devices & feed optics (Caltech + JPL)
PSB Pair
06/01/2003
145 GHz B03 TT Power Spectrum
T map
• Detection of anisotropy signals all the way up to l=1500
(Masi et al., • Time and detector jacknife tests OK
2005) • Systematic effects negligible wrt noise & cosmic variance
the deepest
CMB map
ever
[Masi et al. 2005] Jones et al. 2005
19/20
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
La mappa dell’ universo primordiale con sovrapposta la polarizzazione
Realizzata dal gruppo di Cosmologia di Tor Vergata (Genn. 2005)
14

15. EE Power Spectrum
WMAP (2002)
• Signal extremely small, but
detection evident for EE Wilkinson Microwave Anisotropy Probe
(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
WMAP in L2 : sun, earth, moon are all WMAP
Hinshaw et al. 2006
well behind the solar shield. astro-ph/0603451
Detailed Views of the
1o
Recombination Epoch
(z=1088, 13.7 Gyrs ago)
BOOMERanG
Masi et al. 2005
astro-ph/0507509
Paradigm of CMB anisotropies Power spectrum
k
l
Processed by
smaller than
Power 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
2006 Hinshaw et al. 2006
0
Big-Bang
10-36s
Inflation
3 min
Nucleosynthesis
300000 yrs
Recombination t
15

16. 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
Need for high calibration, <1% beam, calibration, 10% beam,
angular multipole coverage 2-700) multipole coverage 50-
resolution 1000)
Bennett et al. 2003
< 10’ 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= ?
2006
•
• τrec= 0.166+0.076
Hinshaw et al. 2006
PLANCK
2009 Planck is a very
ambitious
experiment.
ESA’s mission to map the Cosmic Microwave Background
Image of the whole sky at wavelengths near the intensity
It carries a peak of the CMB radiation, with
complex CMB
experiment (the
state of the art, a
• high instrument sensitivity (ΔT/T∼10-6)
few years ago)
all the way to L2,
• high resolution (≈5 arcmin)
• wide frequency coverage (25 GHz-950 GHz)
improving the
sensitivity wrt
• high control of systematics
WMAP by at
least a factor 10,
•Sensitivity to polarization
extending the
frequency Launch: 2009; payload module: 2 instruments + telescope
coverage
towards high • Low Frequency Instrument (LFI, uses HEMTs)
frequencies by a
factor about 10 • High Frequency Instrument (HFI, uses bolometers)
• Telescope: primary (1.50x1.89 m ellipsoid)
Galaxy
CMB
16

17. Galaxy Galaxy
CMB CMB
Two Instruments: Low Frequency (LFI) and High Frequency (HFI)
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.
17

18. Measured performance of Planck HFI bolometers (0.1K)
(Holmes et al., Appl. Optics, 47, 5997, 2008)
Multi-moded
=
Photon
noise
limit
Planck-Herschel
Launch
May 14, 2009
15:12 CEST
Telescopio fuori
asse, diametro
specchio principale
1.8 m
18

19. Observing strategy
The payload will work from L2, to Launch
May 14th, 2009
avoid the emission of the Earth, of the
Moon, of the Sun
Boresight
(85o from spin axis)
Cruise
May-June 2009
Field of view
rotates at 1 rpm
Calibrations,
M Scan
Ecliptic plane start July 2009
1 o/day E
L2
HFI Verification / Calibration Plan
e
an
m al pl
ste c ht
-sy FI fo SL) -flig
b H
su , C in
(I AS LIGH, BEAM
Main 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%]
3 months after launch The sky explored by Planck so far (First Light Survey, 2 weeks)
● 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)
19

20. The sky explored by Planck so far (First Light Survey, 2 weeks)
Galactic Plane
20

21. The sky explored by Planck in the First Light Survey, first 2 weeks
High Galactic Latitude (CMB)
21