Archeology of the Universe

Document Sample
Archeology of the Universe Powered By Docstoc
					                                                                                       The universe today is              Galaxies form a “cosmic    SDSS
                                                                                       filled with Galaxies               web” of clusters and voids

        Archeology of the Universe
                                                                                                                              4G                                       us
                                                                                                                                   ly                              m
                        Paolo de Bernardis                                                                                                             nce
                       Dipartimento di Fisica                                                                                                di s

                   Universita’ La Sapienza, Roma

            Colloqui della
 Scuola di Dottorato in Scienze Fisiche                                                                                                                  2dF
    Matematiche e Astronomiche

                 Bologna 06/06/2008

                                                                                    Moreover, the Universe is expanding.
The Universe has not been always the same.                                          How do we know this ?
The Universe Evolved !                                                              We observe light coming from distant
                                                                                    Galaxies, and notice that all wavelengths
How do we know this ?
                                                                                    are systematically shifted to longer
Looking far away is like looking in the past.:                                      (redder) wavelengths.
light can take billion of years to arrive from the
farthest Galaxies we observe.                                                       The farther the galaxy, the larger the shift
                                                                                    (Carl Wirtz, Edwin Hubble 1920-1930).
And the earliest galaxies we see are more
irregular, smaller, redder that the nearby
(current) ones.
So, there has been an evolution in the
morphology of Galaxies                                                                                                       cz

Hubble Ultra-deep field                                                                                                                   modern data

 General relativity tells us that in                                               • It is common experience that an expanding gas also cools
 an homogeneous expanding                                                            down. The Universe does the same.
 universe, where all lengths                                                       • If the Universe has been expanding, it also has been
 expand by the some factor, light                                                    cooling from a higher temperature state.
 wavelengths also expand by the                                                    • The temperature (energy) decrease is responsible for a
 same factor (cosmological                                                           very strong evolution of the content of the Universe.
 redshift, z).                                                                     • In the Very Early Universe the temperature was so high
The classical analogous is the Doppler                                               that it was impossible to have structures like galaxies and
shift, a wavelenght shift proportional to                                            stars. The early Universe was very homogeneous.
the relative speed of the source wrt the                                           • Structures must have formed at some later stage of the
                                                       Hubble law:
observer.                                                                            evolution, when the temperature became low enough.
                                                     redshift           distance

If all lengths expand by the same factor,              z = (Ho/c) d                • When did this process start ?
there is no center of the expansion, and
                                                                Constant           • Can we investigate experimentally the hot, homogeneous
                                                                70 km/s/Mpc
recession velocity is proportional to                                                early universe, and then the transition to a colder,
distance                                                                             structured one ?                      YES, with the CMB

                                                                  • The sequence of events
• Extrapolating all the way back, we would conclude that            depends on the content of
  the Universe started in a Big Bang, an initial state with         different forms of energy in
  infinite density and temperature.                                 the Universe:
• However, we do not really know what happened at the                – Radiation
  Big Bang.                                                          – Matter
                                                                     – Vacuum
• We know that the energy density was so high to be
  beyond the capabilities of current physical description:
  at such high energies, general relativity and quantum
  physics break down, and we do not have a complete,
  unified theory describing ultra-high energy phenomena.
• Physics can describe states with extremely high energy,
  occurring a split-second after the Big-Bang, when the
  temperature was not infinite, but a more comfortable
  1020 K or so.

• There is a lot of photons for each ordinary matter particle     • We believe that this situation is
  in our Universe (109:1) . On the average, we count 400            the result of matter – antimatter
                                                                    annihilations occurring a few μs
  photons/cm3 and << 1 ordinary matter particle per m3.             after the Big Bang, and of a slight
                                                                    asymmetry of matter and
                                                                    antimatter densities.

                                                                                   b + b ⇔ 2γ
                                                                                                      b + b ⇒ 2γ

• This high number of photons is crucial for the evolution of                        few
  the Universe : it means that at early times the energy of the
  Universe was dominated by photons:
• … In principle was light …

                                                                  • As long as the Temperature is higher
• This abundant background of photons                               than 3000K, these photons are
  regulated the nuclear reactions producing                         continuously scattered by free
  nuclei from elementary particles, in the first                    electrons.
  200 s of the evolution of the Universe.
                                                                  • So they follow a random walk. The
• Only in the presence of this exact ratio of                       Universe is opaque to photons.
  photons to ordinary matter nuclear reactions
  can produce the observed abundances of light
  nuclei (George Gamow, in the 50s)
                                                                                                      yr 000


• 380000 years after the big bang the
  Universe cooled below 3000K,
  enough to allow the formation of
  neutral atoms (mostly Hydrogen).
• We call this event recombination.
• The cross-section between photons
  and matter decreased, and photons                                                        • Thereafter, photons travel along
  were released.                                                                             straight paths, and we can do
                                                                                             astronomy, which means that we
                                                                                             can record direct images of

                                                                                             several epochs of the Universe.


                                                                                           • The farthest epoch we can sample
                                                                                             in this way is the epoch of
                                                                                             recombination: looking farther
                                                                                             away (i.e. earlier in the history of
                                                                                             the Universe) is not possible with
                                                                                             photons, because the Univese was
                                        yr 000

                                                                                                                                yr 000
                                                                                             not transparent to photons.



                            Hot gas on the                                                                         Hot gas on the
                            photosphere of the                                                                     photosphere of the
                            Sun (5500 K)                                                                           Sun (5500 K)

                8 light minutes                                                                       8 light minutes
   Here, now                                                                            Here, now

                                                                   Solar granulation                                                                           Solar granulation

                                                                                                               Hot gas in the Early
                                                                                                               Universe, at
                                                                                                               (T=3000 K)

                                                                                                      14 billion light years
                                                                                        Here, now

                                                                                                                                        The BOOMERanG map of the Early Universe

 • Before recombination, ordinary matter and radiation were in such                    • The result of these simulations
   a tight contact that structures made of ordinary matter could not                     is that the observed cosmic web
   exist.                                                                                can be reproduced only if in the
 • Only after recombination gravity succeeds in accreting ordinary                       Universe is also present matter
   matter from the surrounding underdense regions into any                               in a form which does not
   overdensity seed.                                                                     interact with light: dark matter.
 • This is the beginning of the process creating galaxies                              • Dark matter is also necessary to
 • The process is slowed down                                                            explain the rotation of galaxies
   by the expansion of the                                                               and the dynamics of clusters of                                                       2dF

   Universe, and it takes several                                                        galaxies (Zwicky, 1938)
   hundred million years to                                                            • However, to explain the
   form the first gravitationally                                                        formation of the cosmic web, it
   bound structures, and billion                                                         is necessary a particular form of
   years to form the large scale                                                         dark matter: cold (not
   structure of the Universe.                                                            relativistic) dark matter
 • Using supercomputers, it is                                                         • Dark matter is also necessary to
   possible to compute very well                                                         form the first seeds for the
   how gravity works and                                                                 formation of structures before
   produces the cosmic web of                                                            recombination.
   structures we see in the                                                                                                                                              NGC1232
   present universe:                                      Millennium Simulation
                                                                                       • Can we see them ? YES, with the CMB

                       The CMB                                                                                         Image of Solar Granulation

  • All those photons present in the early Universe must                                    Plasma in the
    still exist.                                                                            solar photosphere
  • However, the Universe expanded about 1000 times                                         (5600 K)
    since the recombination epoch. This has a very
    important observational consequence for photons                                 8 light minutes
                                                                    Here, now
    coming from the Early Universe.
  • In fact, what was glowing red light at recombination
    (remember the surface of the sun), with a wavelength
                                                                                           Plasma in the
    of about 1 micron, is now a faint background of                                        cosmic
    microwaves, with wavelengths around 1 mm.                                              photosphere
 • This Cosmic Microwave Background (CMB),                                                 (3000 K)
    predicted by George Gamow in the 50s, was
    discovered in 1964 by Arno Penzias and Robert                                  14 billion light years
                                                                    Here, now
    Wilson. It had been observed a few times before then,
    but always misinterpreted.
                                                                                                                          The BOOMERanG map

                                1992: COBE-FIRAS                                The image of the CMB
  instrument, aboard of                                          • The CMB comes from everywhere, and its spectrum is
  the COBE satellite of                                            basically the same from every direction we look in the sky.
  NASA, has produced                                             • Since discovery of the CMB in 1965, the big challenge for
  in 1992 this definitive                                          experimentalists has been the detection of temperature
  measurement of the                                               fluctuations in different directions of the sky.
  spectrum of the CMB.                                           • These must be present if there are density seeds in the early
• It is a perfect thermal                                          universe, from which structures would grow.
  spectrum (a 2.725 K                                            • A few groups of brave experimentalists in Italy, UK, US,
  blackbody) with                                                  built in 20 years a number of custom experiments to
  deviations from the
  ideal Planck law                                                 measure a map of the CMB, which is the earliest map of the
  smaller than 1 part in                                           Universe we can hope to make using photons.
  10000.                                                         • All these attempts have been frustrating, for at least 27
• The final                                                        years: the more sensitive the experiments became, the more
  confirmation of the                                              isotropic the CMB was demonstrated to be. It looked
  theory of the Hot Big                                            perfectly uniform at a level of 1 part in 10000 or more at all
  Bang.                   Mather et al. 1992                       scales.

        Large-Scale Anisotropy                                                             Horizons
                                                                  • At recombination (t=380000 years), only regions of the
• 1992: COBE-DMR                                                    Universe closer than 380000 light years have had the
  detects the very small                                            possibility (enough time) to interact.
  (10ppm) large-scale
                                                                 • That length, as seen from a distance of >10 billion light
  anisotropy of the CMB.                                            years, has an angular size of about 1 degree.
• The measured spectrum
                                                                                                                                  380000 ly

  requires a scale                                                                                1°
  invariant P(k) (n=1)                                                                             1°            10°
                                                                                                                                              380000 ly

• Its incredible                                                                                                                     T2
  smoothness requires an                                                                     14 000 000 000 ly

  inflationary process                                           • How is it possible that regions separated by more than 1°
  happening in the first                                           are seen in the COBE map to have the same temperature,
  split second after the                                           within 1 part in 10000 ? They could not interact in all
  Big Bang.                                                        the history of the Universe, from the Big Bang to
                                          G. Smoot et al. 1992     recombination ! (the “Paradox of Horizons”)

                       Inflation ?                                                                                  Sub-horizon scales
 • The only known solution to this paradox is the
   inflationary hypothesis                                        • If we want to see the seeds of structure
 • Those regions are not in causal connection at                    formation, we must be able to resolve structures
   recombination, but they had been in causal connection in         smaller than 1°, so that we can see what
   the very early universe, when they occupied a                    happened in regions of the Universe where
   microscopic, isothermal volume of the Universe.                  forces had time to work, and matter clouds could
 • Later, but still very early in the history of the Universe,
   at some phase transition a huge, superluminal inflation        • COBE was a small satellite with two small
   of space happened, boosting microscopical scales to              microwave antennas. The resolution was 10°.
   cosmological scales.                                           • What we need to make this measurement is a real
 • Can we produce a proof that this process ever happened ?         microwave telescope. An angular resolution of
   Yes, with the CMB, in the (near ?) future.                       <1° at a wavelength of a few mm means a
                                                                    telescope mirror larger than 1 m .

                                                                           the BOOMERanG ballon-borne telescope

                                                                 Sun Shield
                                                                                                                          Array                      Differential
                                                                                                                                                     GPS Array

                                                                 Shield                                                                              Primary

                                                                                                               Sensitive at 90, 150, 240, 410 GHz

• The instrument is flown                                        • The image of the sky is
  above the Earth                                                  obtained by slowly
  atmosphere, at an altitude                                       scanning the full payload
  of 37 km, by means of a                                          in azimuth (+30o) at
  stratospheric balloon.
                                                                   constant elevation
• Long duration flights (LDB,
  1-3 weeks) are performad
  by NASA-NSBF over
  Antarctica                                                                                crosslink in BOOM ERanG LDB scans (1 scan/hour sho

• BOOMERanG has been flown                                                                -35          0-11h
  LDB two times:                                                                                      12-23h
                                                                                                                                                           • The scan center
                                                                  declination (degrees)

• From Dec.28, 1998 to                                                                    -40                                                                constantly tracks the
  Jan.8, 1999, for CMB                                                                                                                                       azimuth of the lowest
  anisotropy measurements                                                                 -45
                                                                                                                                                             foreground region
• In 2003, from Jan.6 to                                                                  -50
                                                                                                                                                           • Every day we obtain a
  Jan.20, for CMB polarization                                                                                                                               fully crosslinked map.
  measurements (B2K).                                                                     -55                                       elev. = 45
                                                                                                                                                           • This is the key for an
                                                                                                  3             4         5              6                   accurate map of the
                                                                                                          Right Ascension (hours)                            sky

145 GHz                                                                               M1,M2 = first and second
T map                                                                                 halves of the observations
                                                                                      of the deep region.
(Masi et al.,                                                                         sum=(M1+ M2)/2
2005)                                                                                 diff =(M1- M2)/2

the deepest
CMB map

                                                                          • In the deep survey the S/N is high.
                                                    [Masi et al. 2005]
                                                                                                                   ∆Trms = (90.2+2.3) μK
                                                                          • The fluctuations are gaussian.

                        WMAP (2002)                                      WMAP in L2 : sun, earth, moon are all
            Wilkinson Microwave Anisotropy Probe                           well behind the solar shield.

                                             Hinshaw et al. 2006

                                                                             WMAP 3 years              BOOMERanG-98      BOOMERanG-03
                                                                              23-94 GHz                   145 GHz           145 GHz
                                                                         The consistency of the maps from three independent
                                                                         experiments, working at very different frequencies and
                                                                         with very different mesurement methods, is the best
 Detailed Views of the                                                   evidence that the faint structure observed
 Recombination Epoch                                                     •is not due to instrumental artifacts
 (z=1088, 13.7 Gyrs ago)                                                 •has exactly the spectrum of CMB anisotropy, so it is
                                                                         not due to foreground emission
                     BOOMERanG                                           •The comparison also shows the extreme sensitivity of
                     Masi et al. 2005                                    cryogenic bolometers operated at balloon altitude (the
                                                                         B03 map is the result of 5 days of observation)

  How does the                                                                      Physics                                                                                                                           14 Gly
  image of the early

                                                                                     of the                                                                                                                  Critical density Universe Ω=1
                                                                                    Primeval                                                                                                            1o
  universe form ?                                                                 fireball and
                                                                                   very early

                                 of                                                                                                                                                                                                   Ω>1
                               space                                                                                                                                                                 2o
                                                                                                                                                                                                High density Universe

                          14 billion light years
    Here, now                                                                                                                                                                                            0.5o
                                                                                                                                                                                                       Low density Universe Ω<1

                                                                      The BOOMERanG map of the last scattering surface

                                                                                                                                                                                Density perturbations (Δρ/ρ) were oscillating in the primeval plasma (as a result of the
 PS                                     PS                                     PS                                                                                               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
     0          200                 l       0           200               l        0          200                                                                   l
     High density Universe                  Critical density Universe               Low density Universe
               Ω>1                                       Ω=1                                                                 Ω<1
                                                                                                                                                                                                             Pressure of photons
                                                                                                                                                                                 overdensity                 increases, resisting to the
                                                                                                                                                                                                             compression, and the
                                                                                                                                                                                                   t         perturbation bounces back
                             2o                                1o                                                                                                                                                 Before recombination T > 3000 K

                                                                                                                                                      0.5o                                         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.

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.                                                                                                                                   First evidence (2000)
                                                                                              The angle subtended depends on the geometry of space

    Size of sound horizon                                                                                                                                                                                                                  from BOOMERanG
                             v                  v               v
                                                                                                                                                         2nd dip
                                        C               R

  size of perturbation
  (wavelength/2)                        v                v

                                                C              R
                                                                                                                                                        2nd peak

                                            v                     v

                                                                                                                                                          1st dip
                                                    v                    300000 ly

                                                              C                                                                                      1st peak
                                                                                                                                                                                                                                              Angular scale (deg)
 0y                              time                   300000 y
Big-bang                                             recombination                       Power Spectrum

      WMAP & BOOM/98: Power Spectra
                                                         Best fit of
                                                         BOOMERanG data
 l(l+1)cl /2π (μK )





                             0   200   400         600         800       1000

2003                                         multipole

                                                                                    Paradigm of CMB anisotropies                                               Power spectrum


                                                                                                                                        Processed by
                                                                                     smaller than

                                                                                                             Power                                             of CMB
                                                                                                                                     causal effects like
                                                                                                             spectrum of                                       temperature

                                                                                                                                    Acoustic oscillations

                                                                                                             perturbations          Radiation pressure
                                                                                                                 Gaussian,          from photons

                                                                                                                 adiabatic          resists gravitational
                                                                                   Quantum                       (density)          compression
                                                                                   fluctuations                    horizon              horizon                                 horizon
                                                                                   in the early
                                                                                   Universe                                             (ΔT/T) = (Δρ/ρ) /3
                                                                                                                                               + (Δφ/c2)/3

                                                                                                                                                                   l( l+1) cl
                                                                                                                                               – (v/c)•n
                                                                                      larger than


                                                                                                                                                        plasma      neutral

2006                                                         Hinshaw et al. 2006
                                                                                                                                3 min
                                                                                                                                                                  300000 yrs
                                                                                                                                                            Recombination                 t

      Cosmological Parameters                                                      • There is a minimalist model with only 6 free parameters (Ho, Ωo, Ωb,
                                                                                     ΩΛ, n, A) describing very well the angular power spectrum of the
        Assume an adiabatic inflationary model, and                                  CMB, but also other measurements:
       compare with same weak prior on 0.5<h<0.9                                      – The spectrum of the CMB
 WMAP                                        BOOMERanG                                – The abundances of primordial light elements
 (100% of the sky, <1% gain                  (4% of the sky, 10% gain                 – The expansion of the Universe
    calibration, <1% beam,                     calibration, 10% beam,                 – The fluxes of high redshift SN1a “candles”
    multipole coverage 2-700)                  multipole coverage 50-
                                               1000)                                  – The large-scale distribution of galaxies and Ly-α clouds
 Bennett et al. 2003
                                             Ruhl et al. astro-ph/0212229             – The polarization of the CMB …. Etc …
                                                                                   • So a question could be: “ are we done with cosmology ?...”
                                                                                   • Not at all. The “model” is still not satisfactory, since it requires
 • Ωο =1.02+0.02                             • Ωο = 1.03+0.05                        “dark matter”, “dark energy”, and also an “inflation phase” in the
                                                                                     very early universe, and there is no evidence from non-cosmological
 •               ns = 0.99+0.04 *            •   ns = 1.02+0.07                      physics for these three components.
 •               Ωbh2 =0.022+0.001           •   Ωbh2 =0.023+0.003                 • As a CMB experimentalist, I would rather try to answer two
 •               Ωmh2 =0.14+0.02             •   Ωmh2 =0.14+0.04                     different questions:
 •               T = 13.7+0.2 Gyr            •   T=14.5+1.5 Gyr                       – are there open issues in CMB anisotropy measurements ?
                                             •   τrec= ?                              – are there critical CMB observations still to be done ?
 •               τrec= 0.166+0.076

                                                                                    • There is a minimalist model with only 6 free parameters (Ho, Ωo, Ωb,
                                                   Normal                             ΩΛ, n, A) describing very well the angular power spectrum of the
                                         Radiation Matter                             CMB, but also other measurements:
                                          < 0.3%    4%                     Dark        – The spectrum of the CMB
                                                                           Matter      – The abundances of primordial light elements
                                                                                       – The expansion of the Universe
                                                                                       – The fluxes of high redshift SN1a “candles”

                                                                                       – The large-scale distribution of galaxies and Ly-α clouds

                                                                                       – The polarization of the CMB …. Etc …

                                                                                    • So a question could be: “ are we done with cosmology ?...”
                                                                                    • Not at all. The “model” is still not satisfactory, since it requires

                                                                                      “dark matter”, “dark energy”, and also an “inflation phase” in the

                                                                                      very early universe, and there is no evidence from non-cosmological
                                                                                      physics for these three components.
                                                                                    • As a CMB experimentalist, I would rather try to answer two
                                        Dark                                          different questions:
                                       Energy                                          – are there open issues in CMB anisotropy measurements ?
                                        74%                                            – are there critical CMB observations still to be done ?
                                                                                                                                                 YES !

                              CMB Experiments

  High Resolution
    Anisotropy                   λ-spectrum            Polarization
                              of the CMB and
                               its anisotropy
                                                       • Velocity fields
   • Damping tail & param.s
                                                       • Inflation
   • SZ & Clusters
                               • SZ distortions        • Reionization
   • nature of dark matter     • Early Metals
                               • Recombination lines   • Magnetic fields
   • ……..                      •…..
                                                       • …..

ESA 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

Launch: 2008; payload module: 2 instruments and telescope
• Low Frequency Instrument (LFI, HEMTs)
• High Frequency Instrument (HFI, bolometers)
• Telescope: primary (1.50x1.89 m ellipsoid)

                                  Observing strategy
                              The payload will work from L2, to
                              avoid the emission of the Earth, of the
                              Moon, of the Sun
                                                           Boresight                            150K
                                                     (85o from spin axis)                                  50K

                                                          Field of view
                                                        rotates at 1 rpm              50K

Ecliptic plane
                        1 o/day   E

                                                                            • And the full cryogenic qualification model
                                                                              has been vibration and thermal tested.

                   FM Calibrated !
  • The HFI flight model has been recently
    calibrated at IAS.
  • The goal performance has been achieved.

  • So we can expect in three years from now :
       – A precisely calibrated instrument operating in
         the best possible space environment
       – Maps covering the full wavelength range and
         angular resolution of primary CMB anisotropy

Upcoming TES array instruments:                                                    Sunyaev-Zeldovich effect
• SCUBA2            10000 pixels          Filled array             CMB
• APEX              ~ 500 pixels          Horn coupled                                      Inverse Compton scattering of CMB photons
                                                                                            against hot electrons in the intergalactic
• SPT               ~ 500 pixels          Horn coupled
                                                                                            medium of rich clusters of galaxies
• ACT               ~ 3000 pixels Filled array
• CLOVER            ~ 500 pixels          Horn coupled                   γ
                                                                                            About 1% of the photons acquire about 1%
• OLIMPO            ~ 100 pixels          Horn coupled                                      boost in energy, thus slightly shifting the
• FIBRE                                                        Cluster            e-        spectrum of CMB to higher frequencies.
• POLARBEAR, EBEX                                                                                     ΔT/T ~ 10-4
• MAMBOTES                                                                                  The result is a decrease of CMB brightness
                                                                                            in the line of sight crossing the cluster at
                                                                                   γ        ν<217 GHz, and an increase at ν>217 GHz

                                                                                            Independent of redshift !

OLIMPO        (PI Silvia Masi, Roma)                         • 4 frequency bands
                                                               simultaneously.                                           Uniqueness of
•   Focal plane can host >400 bolometers
•   from Cardiff (P. Mauskopf) and Genoble (P. Camus)
                                                             • Optimally sample the
                                                               spectrum of the SZ
                           150 GHz 220 GHz 340 GHz 540 GHz                                                                7keV
                                                             • Opposite signals at                                        10keV

                                                               410 GHz and at 150                         4.0x10

                                                               GHz provide a clear

                                                               signature of the SZ
                                                                                            ΔI (mJy/sr)

                                                               detection.                                 2.0x10

                                                             • 4 bands allow to clean
                                                               the signal from dust                           0.0        150   240     410     600
                                                               and CMB, and even to
                                                               measure Te
                                                             • Resolution: 2x(Planck)
                                                             • Detectors: 10x(Planck)                               -4
                                                             • Integration time per           0                               200      400     600   800
                                                               cluster: 10x(Planck)                                                  ν (GHz)
                                                               (40 clusters/flight +
                                                               blind survey)                                              -     0      +        +

                                                           Microwave                                                  γ rays
                                                           Background                   Cosmic
                                                          Power Spectrum of                                    χ−χ annihilation photons
                                                           CMB anisotropy
                                                                                                                in X and γ-rays spectra
                                                        Observation of SZ effect   χ−χ annihilation products
                                                                                        in CR spectra                    ……
                                                          in selected clusters

                                                                 ………                        ………
Flights: 2007 & 2008

              What is Dark Matter ?                        Dark Matter Annihilation Products
• Hp: Weakly Interacting Supersymmetric Particles
• Lightest one predicted by SUSY : Neutralino    χ
• Could be measured by LHC
•  χs tend to cluster in the center of astrophysical
• Annihilation of Neutralinos would produce fluxes of
    –   Neutral and charged pions
    –   Secondary electrons protons
    –   Neutrinos
    –   etc.
• They produce various effects
• One of them is the SZ from the charged
  component (see Colafrancesco, 2004)

        SZ effect from χχ annihilation                                  What is Dark Matter ?
                                                        • Hp: Weakly Interacting Supersymmetric Particles (WIMPs)
                                                        • Lightest one predicted by SUSY : Neutralino                χ
                                                        • Could be measured by LHC
                                                        • χs tend to cluster in the center of astrophysical structures
                                                        • Annihilation of Neutralinos would produce fluxes of
                                                            –   Neutral and charged pions
                                                            –   Secondary electrons protons
                                                            –   Neutrinos
                                                            –   etc.
                                                        • They produce various effects
                                                        • One of them is the SZ from the charged component (see
                                                          Colafrancesco, 2004)
                                                        • Subdominant with respect to SZE from the gas.
                                                        • We need clusters where Dark Matter and Baryonic Matter
                                                          are separated.

                                                   1E0657-56                                                                                1E0657-56

                 9’                                                                                      7.5 ’

SZ effect from DM                     [Colafrancesco 2004 , A&A, 422, L23]
                                                                                  SZ effect at clump centres

                                    ΔI(x) = I(x) – I0(x)

                                      I0(x)                  Ith(x)


                                                          ν' 4
                                     thermal e-              =
                                                          ν 3
                                                          ν 4 2
                                                           '                                    [Colafrancesco, de Bernardis, Masi, Polenta & Ullio 2006]
                                     relativistic e-         = γ −1
                                                          ν 3

                                                                                     Isolating SZDM (at 223 GHz)

                                                                             Mχ = 20 GeV            Mχ = 40 GeV                   Mχ = 80 GeV

                                                                             The SZE from the hot gas disappears at x0,th (∼ 220-223 GHz)
                                                                             while the SZDM expected at the locations of the two DM clumps
        [Colafrancesco, de Bernardis, Masi, Polenta & Ullio 2006]            remains negative and with an amplitude and spectrum
                                                                             which depend on Mχ.
                                                                                                        [Colafrancesco, de Bernardis, Masi, Polenta & Ullio 2006]

     Spectroscopic Active Galaxies And Clusters Explorer
                                                                                          Did Inflation really happen ?
•   The ideal continuation of OLIMPO                                               • We do not know. Inflation has not been
•   Selected by ASI for a phase-A study as a small mission
                                                                                     proven yet. It is, however, a mechanism able
                                                                                     to produce primordial fluctuations with the right
•   2.6 m telescope + FTS spectrometer on a Soyuz
•   Spectra of thousands of SZ clusters and AGNs
                                                                                   • Four of the basic predictions of inflation have
• Uni. La Sapienza / Uni. Mi. Bicocca / Uni. Genova / Kayser Italiana / ASDC-ASI
                                                                                     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.

                       CMB polarization                                                          y                                                y
                                                                                                                    -10ppm           +10ppm
• 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,                                                                 x                                         x
  the scattered radiation acquires some degree of linear                               +                      +
                                                                                                     -                                  -             -    -
                            Last scatte                                                                                      y
                                        ring   surface                                               -                                                +


                                                                                          = e- at last scattering

                                                                                    Quadrupole from P.G.W.
                   If inflation really                                             • If inflation really happened:
                                                                                         It stretched geometry of space to
                       happened…                                                         nearly Euclidean
                                                                                         It produced a nearly scale invariant
                                                                                         spectrum of gaussian density
    • It stretched geometry of                                            OK             fluctuations
      space to nearly Euclidean                                                          It produced a stochastic background of
                                                                                         gravitational waves: Primordial G.W.
    • It produced a nearly scale                                                         The background is so faint that even
      invariant spectrum of density                                       OK             LISA will not be able to measure it.
      fluctuations                                                                 • Tensor perturbations also produce
                                                                                     quadrupole anisotropy. They generate
    • It produced a stochastic                                                       irrotational (E-modes) and rotational
      background of gravitational
                                                                          ?          (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

                    B-modes from P.G.W.
• The amplitude of this effect is very small, but                                                Pure E(left) & B(right)
  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
  ⎛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 ⎥
• 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.                                                        Can you spot the difference ??!!

                 E-modes & B-modes                                              The signal is extremely weak
  Spin-2 quantity                                      Spin-2 basis
           (Q ± iU )(n ) =∑ alEm ± ialBm           )     Y
                                                       ± 2 lm
                                                                (n )            • Nobody really knows how to detect this.
                                                                                   – Pathfinder experiments are needed
 • From the measurements of the Stokes Parameters Q                             • Whatever smart, ambitious experiment we
   and U of the linear polarization field we can recover                          design to detect the B-modes:
   both irrotational and rotational alm by means of                                – It needs to be extremely sensitive
   modified Legendre transforms:
 E-modes produced by scalar and tensor perturbations
                                                                                   – It needs an extremely careful control of
                 r             r           r               r           r             systematic effects
            dΩW (n )[(Q + iU )(n )+ 2 Ylm (n ) + (Q − iU )(n )− 2 Ylm (n )]
alEm =
                                                                                   – It needs careful control of foregrounds
                                                                                   – It will need independent experiments
B-modes produced only by tensor perturbations
                   r             r           r               r           r           with orthogonal systematics.
              dΩW (n )[(Q + iU )(n )+ 2 Ylm (n ) − (Q − iU )(n )− 2 Ylm (n )]
         2i ∫
alBm =
                                                                                • There is still a long way to go: …

                                                                                Universita’ di Roma, La Sapienza:                      Cardiff University: P. Ade, P. Mauskopf
                                                                                P. de Bernardis, G. De Troia, A. Iacoangeli,           IFAC-CNR: A. Boscaleri
 • The second LDB flight of BOOMERanG was                                       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
   devoted to CMB polarization measurements                                     Veneziani                                              CITA: D. Bond, S. Prunet, D. Pogosyan
                                                                                Case Western Reserve University:                       LBNL, UC Berkeley: J. Borrill
 • Was motivated by the desire to measure                                       J. Ruhl, T. Kisner, E. Torbet, T. Montroy              Imperial College: A. Jaffe, C. Contaldi
   polarization :                                                               A. Lange, J. Bock, W. Jones, V. Hristov
                                                                                                                                       U. Penn.: M. Tegmark, A. de Oliveira-Costa
                                                                                                                                       Universita’ di Roma, Tor Vergata: N. Vittorio,
     – at 145 GHz (higher ν wrt WMAP, DASI, CBI etc.)
                                                                                University of Toronto:                                 G. de Gasperis, P. Natoli, P. Cabella
                                                                                B. Netterfield, C. MacTavish, E. Pascale

     – with bolometers (vs. coherent amplifiers of WMAP,
       DASI, CBI etc.)
     – controlling the dominant foreground (dust) by
       means of simultaneous observations at higher
       frequencies (245, 345 GHz)
     – in one of the best sky regions (foreground-wise)
     – in a multipoles range where the polarization signal
       can be higher than the foreground signal.

                     Masi et al. astro-ph/0507509         :   instrument & maps   PSB devices & feed optics (Caltech + JPL)
 First release of    Jones et al. astro-ph/0507494        :   <TT>
data: July 2005      Piacentini et al. astro-ph/0507507   :   <TE>
    Five papers:     Montroy et al. astro-ph/0507514      :   <EE>
                     MacTavish et al. astro-ph/0507503    :   cosmological                                   PSB Pair

             Silvia Masi   Francesco              Bill Jones
                           Piacentini    Tom Montroy     Carrie MacTavish


                                                                                   From Page et al. 2006


Where do we go from here                                                          Sensitivity

•   Polarization measurements do not constrain
                                                                                  •                        B03 has shown that Polarization Sensitive
    parameters better than anisotropy                                                                      Bolometers work well for CMB polarization
    measurements, yet.                                                                                     measurements.
•   Most of the weight in the results above is in                                 •                        Their sensitivity is close to be photon-noise-
    Temperature power spectra.                                                                             limited. In Planck-HFI the same bolometers
•   If we want to constrain better the cosmological                                                        will be cooled a factor 3 more and will be
    model, and finally detect B-modes, and we need                                                         limited only by quantum fluctuations of the
    to improve in three ways:
                                                                                                           CMB itself. It is useless to improve the
                                                                                                           detector noise below the photon noise limit.
    1. Sensitivity
    2. Control of systematics
    3. Knowledge of foregrounds

    A post-Planck mission                                                                       Sensitivity
•       Planck will or will not detect Inflationary B-Modes (depending on
        amplitude, foregrounds, systematics… and if they are really
        there).                                                                                 •   At variance with interferometers,
•       In a diffraction limited 150 GHz survey, CMB BLIP gives 1 μK in                             Bolometer technology is easily scalable,
        1 min of integration. But we need to observe 105 pixels !
                                                                                                    and the throughput can be larger than λ2.
                                                                                                •   Focal planes hosting thousands of
                                                                   150 GHz,10% BW, λ

                                         10                        150 GHz, 10% BW, 1 cm sr
                                                                                            2       bolometers are being developed already.
                                                                     30 GHz, 10% BW, λ
                 error per pixel (μK)



                                                   CMB BLIP
                                               1     10     100          1000    10000
                                                          integration time (s)

•       We need to increase the mapping speed using more detectors
        than in the Planck focal plane.

    Large Bolometer Arrays                                                                      Large Bolometer Arrays
    •     > 1000 TES bolometers for the South Pole                                              •   > 1000 TES bolometers for SPIDER a proposed
          Telescope devoted to SZ (Adrian Lee, Berkeley)                                            spinning polarimeter on a LDB (Andrew Lange,
                                                                                                    Caltech) devoted to large scale CMB polarization

    Large Bolometer Arrays
    •     >1000 TES bolometers for the EBEX CMB
          polarization balloon telescope (Shaul Hanany,


                                                                                                                                              From the

    Control of Systematic Effects
•    B03 has shown that systematic effects can be
     controlled by a combination of
     –   Multifrequency capabilities
     –   Scan variation
     –   Polariziation angle redundancy
     –   Variations of observing conditions
     –   Accurate pre-flight and in-flight calibration
•    This was OK at the level of sensitivity of B03 (i.e. 3σ
     detection of E-modes, 4 μK rms).
•    Nobody knows how to control systematics for a B-
     modes experiment (<0.1 μK rms).
•    The only way is to experiment !
•    Calibration sources must be found and characterized.
•    Balloon and Antarctica experiments are necessary to
     test the technique/methodology before to start the                                              From
     design of a B-modes space mission.                                                              C. Lawrence, PoS (CMB2006) 012

    Control of Foregrounds
•    Diffuse Dust emission is polarized at 10% in the plane
     of the Galaxy. See astro-ph/0306222 “First
     Detection of Polarization of the Submillimetre Diffuse                     10                          Power
                                                                                      τ=0                           sp
     Galactic Dust Emission by Archeops”.                                                                  dust an ectrum of

                                                                                            scalar T               isotrop
•    Its polarization will have both E-modes and B-modes.                                   scalar E
                                                                                                                           y @15
                                                                                                                                 0 GHz
•    We know that at 150 GHz at high latitudes the PS of

                                                                                 1          tensor T        Power                     E

     dust emission is about 1% of the PS of CMB                                             tensor E       dust p
     anisotropy (Masi et al. Ap.J. 553, L93-L96, 2001)                                                            olariza m of
                                                                                            tensor B                     tion @
                                                                                                                               150 G
•    So we naively expect B-modes from dust                                                                                          Hz
     polarization PS at a level of 10-4 of the
     anisotropy.                                                                                                            B
•    This is an important foreground for B-modes of CMB,
     whose level is also about 10-4 of anisotropy !                            0.01
                                                                                              10                     100             1000
•    These are only rough estimates. We know very little
     about the configuration and distribution of the                                               10o                     1o
     magnetic fields aligning the dust grains.


               BOOMERanG-FG                                        03
                                                                                                                                   140 GHz
    • We plan to re-fly B03 with an                                                                                                PSB
      upgraded forcal plane, to go after
      foreground cirrus dust polarization.                                                                                          240 GHz
                                                                                                                                    340 GHz
    • This information is essential for all
      the planned B-modes experiments                          BOOMERanG-
      (e.g. BICEP, Dome-C etc.) and is very
      difficult to measure from ground.                                 340 GHz                                                     140 GHz
    • The BOOMERanG optics can host an                                  PSB
      array of >100 PSB at >350 GHz.

                                                                        Frequency range complementary to PILOT
                                                                            (higher f. J.F. Bernard, Toulouse)

              A post-Planck mission                                                                   • European proposal recently
                                                                               B-Pol                    submitted to ESA (Cosmic
                                                                                                        Vision). PI PdB.
•     A post-Planck mission, with a large array of                                                    • ESA encourages the
      sensitive polarized detectors, is needed to                                                       development of technology and
      detect B-modes and constrain inflationary                                                         resubmission for next round
                                                                                                      • Detector Arrays development
      parameters (energy scale, r, nT, V(φ) …)                                                          activities (KIDs in Rome, TES
     –   NASA – Beyond Einstein : Inflation Probe                                                       in Genova etc.)
     –   ESA - Cosmic Vision : B-Pol                                                                  • A balloon-borne payload being
                                                                                                        developed with ASI (B-B-Pol).
•     Meanwhile, laboratory, ground-based, and
      balloon-borne experiments are necessary
      develop the needed technology

              Pre-phase-A study for the B-Pol program                  Sensitivity and frequency coverage: the focal plane
                                                                     • Baseline technology: TES bolometers arrays
                                                                        Corrugated feedhorns               Sub-K, 600 mm
    • A coordinated effort of the italian CMB community                 for polarization purity and
      to measure the polarization of the CMB                            beam symmetry

    • Study and compare the performance of
      – Balloon option
      – Small satellite option
      – Medium satellite option


                                        Optical system:
                                                                               B-B-Pol: The Balloon Option
                                        • Wide field,
                                                                       WHY ?
                                        • low cross-pol,
                                        • low emissivity                • Get important science
                                                                          (complementary to NASA’s SPIDER, EBEX)
                                        Possible solution:
                                        modified telecontric            • Validate needed technology, for next round of
                                        telescope                         ESA cosmic vision
                                                                       HOW ?

                                                                        •   ASI polar-night flight -> large sky coverage
                                                                        •   Three instruments to cover from 40 to 220 GHz
                                                                        •   Low angular resolution – large scales
                                                                        •   High-Throughput Channels – High sensitivity
                                                                        •   Single-mode channels – Foregrounds
                                                                        •   Large ground shields
                                                                        •   No optics – no spurious polarization

                                 Worksheet Sensitivity

Worksheet Performance

                        37 detectors

                                        12 cm

                                                        2K                             B-B-Pol: A spinner in the polar night
                          W                 Polyethilene                      0.3K
                                     ri d                                              • Can provide extremely competitive
Beam 2o FWHM
                                                                                         measurements of CMB polarization at
                                                                                         large angular scales.
               25 cm
               diam                                                                    • Is complementary to NASA’s SPIDER and
                                                              40 overmoded
                                                              Detectors, diam 1.7 cm     EBEX
                                                              (10 modes @ 150 GHz,
                                      Polyethilene             20 modes @ 220 GHz)     • Will qualify, producing great science
B-B-Pol: High                                                                            results, italian technology, in view of next
Frequency                                     0.3K                                       Cosmic Vision call.
Instrument                                           40 overmoded                      • Will exploit the unique ASI-ARR capability
(one of the two                                      Detectors, diam 1.7 cm
bands shown)                                         (10 modes @ 150 GHz,
                                                                                         to launch long duration balloons in the
                                                      20 modes @ 220 GHz)                polar night

• TES arrays are being prepared for
                                                                                        • The readout system for TESs requires SQUIDs
   –   South Pole Telescope                                                               and is very complex.
   –   APEX (Atacama)
                                                                Large Dishes
   –   ACT (Atacama)
                                                                                        • KIDs (see e.g. Zmuidzinas, Caltech) represent a
   –   IRAM 30m dish (Pico Veleta)
                                                                                          good alternative because are intrinsically
   –   PolarBear (White Mountain)
   –   EBEX
   –   SPIDER
                                                                Balloons                • Cold electron bolometers (e.g. Kuzmin, Chalmers)
   –   OLIMPO
   –   B-Pol                                                                              represent a good alternative because the readout
   –   SAGACE ….                                                Satellites                system is much simpler

                                                                              RC       0.3K - 0.1K                                         RC
                                                                                             GHz RF (…+fN-1+fN+fN+1+…)

                                                                                                        CMB              CMB               CMB

                                                                                            Pixel N-1          Pixel N         Pixel N+1
                                                                                               fN-1               fN              fN+1
                                                                 Mazin (Caltech)

                    • First prototype: a 0.3K Al resonator @ 6 GHz
                    • Currently under test

                        We have a true image of the early universe,
KIDs (RIC – INFN)     And we have new intriguing questions to answer
                      New techniques to develop .. A lot of work to do.


Shared By: