Spectral Distortions of CMB

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Spectral Distortions of CMB

• C. Burigana, A. De Rosa, L. Valenziano, G.
  Morgante, F. Villa, R. Salvaterra,
• P. Procopio and N. Mandolesi

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Cosmic Microwave Background Radiation
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CMBR
SPECTRUM
Has the CMBR a black body spectrum?
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CMB Spectrum measuresWP 1430 C. Burigana, N.
Mandolesi, L. Valenziano
Recent measures of CMB spectrum (collected by
Burigana and Salvaterra, 1999)
?gt1cm typical error gt 0.1 K
FIRAS measures typical error 0.0001 K
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• Impact of various sources of errors note the
  atmosphere relevance

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Spectral distortions
The Kompaneets equation in cosmological contest
provides the best tool to compute the evolution
of the photon distribution function, but a
numerical code is needed!
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Cosmological applications
Primordial distortions
Free-free distortions
Late distortions
Related (mainly) to the reionization history of
the universe
Cosmological application of a numerical code for
the solution of the Kompaneets equation,
P.Procopio and C.Burigana, INAF-IASF Bologna,
Internal Report, 421
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Theoretical CMB Spectral Distortions
Distorted spectra in the presence of a late
energy injection with ??/?i 5 x 10-6 plus an
early/intermediate energy injection with ??/?i
5 x 10-6 occurring at yh5, 1, 0.01 (from the
bottom to the top in the figure the cases at
yh5 and 1 are indistiguishable at short
wavelengths solid lines) and plus a free-free
distortion with yB10-6 (dashes).
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Cosmological application
Te/TR 104 zR 20 d?/? 10-5
One of the representative cases
Distortions due to reionization of the universe
at low redshifts
? m 1 ?? 0
? m 0.29 ?? 0.73
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In the Planckian Hypothesis limits achievable
with a new low frequency experiment DIMES
Example 6 freq. channels between 2 90 GHz
Limits achievable with a low frequency experiment
with the same FIRAS sensitivity
Current limits
Hypothesis to be checked
Burigana and Salvaterra, 2003
Cosmic time
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In the presence of distortions results
achievable with a new low frequency experiment
300.000 yr
1 yr
Recombination
103
Results obtainable for an early physical
process. Same FIRAS sensitivity but at low
frequencies best fit (dashes) and errors at 95
C.L.(solid).
Burigana and Salvaterra, 2003
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CMB spectrum Key parametersConfiguration A and B

• Frequency operating range 0.4 50 GHz (75 - 0.6
  cm)
• Spectral resolution 10
• Angular resolution 7/8
• Sensitivity lt 1 mK sec-1/2
• Field of View gt 104 deg2
• Final sensitivity (E.O.L) better than 0.1 mK per
  resolution element
• Low sidelobes optics
• Ground shield
• avoid ground signal pickup
• thermal stability

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Calibrator requirements

• Return Loss lt -60dB in the whole frequency range
• Intercalibration between frequency bands better
  than 30 ?K
• Thermal stability better than 1 mK with well
  sampled temperature monitoring (temperature
  accuracy better than 10 ?K)

The ARCADE calibrator
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Radiometers

• Differential radiometers (using low noise
  amplifiers)
• Absolute calibration

One of the ARCADE radiometers (Kogut, 2002)
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Sketch of the large payload
Mass 1000 Kg, height 6 m, deployed in a
shaded crater
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• Scientific performance as function of (low)
  frequency coverage
• C 2, 5, 8 freq. channels, 0.48, 1.9, 7.54 cm
• D 3, 6, 9 freq. channels, 0.75, 3.0, 11.9 cm
• E 3, 5, 7 freq. Channels, 0.75, 1.9, 4.75 cm
• R recent data _at_ l 1cm
• F COBE/FIRAS
• Note that even with
• observations _at_ l 5cm
• the improvement is
• very good!

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New Concept Design Requirements

• Mass lt 300 Kg
• Simplify cooling system
• Location at the pole
• Continuous operation (day and night)
• Simplify pointing system
• Autonomous, unmanned operation
• Simplify deployment

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Reduce Dimension and Mass

• Reduce the number of channels
• Use a smaller payload
• Use a smaller cooler
• Select highest frequency bands
• Reduce horn and calibrator dimension
• Enlarge FOV (14 FWHM)
• Reduce horn dimensions
• Passive cooling for the optics
• Use a smaller cooler
• Introduce steerable optical system
• Reduce horn dimension
• Avoid an alt-az mounting

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New Location

• Select a location at the Pole
• Reduce the size of passive cooling radiators
• Reduce the observed portion of the sky
  (acceptable from the scientific point of view)
• Avoid rover and deployment system (reduce mass)
• Shaded crated location not strictly required
• Simplified deployment on the final site
• Operation on the landing module possible
• Power generation from solar panels on the payload
• Operation from the near side of the Moon
• Higher frequency less affected by man-made
  interference

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New Payload Concept (conf. E)

• 3 channels
• 6 GHz
• 15 GHz
• 63 GHz
• FOV 14 deg
• Passive cooling for the optics
• Steerable optical element at horn aperture

6GHz Channel
15GHz Channel
Steerable Mirror
Feed Horn
63GHz Channel
Absolute Reference_at_4K
Internal Reference _at_4K
Thermal Link _at_4K
Thermal Link _at_4K
Cold Head
Radiometer _at_4K
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New Payload Concept
15GHz Channel
6GHz Channel

• Pointing system obtained using steerable mirrors
  and Moon rotation

63GHz Channel
Cold Head
Compressor
Electonics box
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Location

• Location at the Pole
• Passive cooling possible. Smaller radiators
• Easy deployment, unmanned operation
• Shields deployed in-situ
• Operation from the lander possible
• Solar panels on the payload

Instrument
External passive cooling Shield
Middle Shield
Internal passive cooling shield
Coolers Radiators
Solar panel
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• Estimated mass lt 200 Kg
• In situ overall dimension diameter 8 m,
  height 3 m
• Passive shield deployed
• Estimated power requirements 3 kW
• Continuous operation possible

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CONCLUSIONS

• The Moon is a unique opportunity for accurate cm
  dm CMB spectrum measures free from atmosphere
  contamination
• dm observations requires 103 Kg experiments
• cm observations need 102 Kg experiments and
  represents,
• _at_ 0.1 mK sensivity, a great improvement with
  respect to the current observation status
• in particular for free-free distortions
  BE-like (early) distortions
• A compact design for early cm experiments has
  been proposed
• Definitive cm dm missions will map the cosmic
  thermal history with high precision up redshifts
  of 107

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• Thanks for the attention!

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KYPRIX
How does it work?
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KYPRIX update(s)
90 first KYPRIX release by Carlo Burigana
2004-2005 update related to the NAG
libraries sensitivity e
efficiency increased
introduction of the cosmological constant
2006-2007 CPU platform transfer (still
in progress) activity update related to the
relative abundances of H and He introduction
of the ionization fraction of e-
Updating a numerical code for the solution of
the Kompaneets equation in cosmological context,
P.Procopio and C.Burigana, INAF-IASF
Bologna, Internal Report, 419
Accuracy and performance of a numerical code
for the solution of hte Kompaneets equation in
cosmological context, P.Procopio and
C.Burigana, INAF-IASF Bologna, Internal Report,
420
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Reionization