Primordial Resonant Lines in the early universe

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Primordial Resonant Lines in the early universe

• Roberto Maoli
• Univ. di Roma "La Sapienza" IAP Paris

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Direct observation of the universe
z1100 CMB anisotropies

Dark ages
Reionization Structure formation
z5-10 first quasars
z0 today universe
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Secondary anisotropies of the CMB

• Rees-Sciama effect
• variation of the gravitational potential during
  the non linear evolution of the perturbation
• Vishniac effect
• non linear second order effect produced by the
  coupling between the velocity and the density
  fluctuation
• kinetic Sunyaev-Zel'dovich effect
• Thomson scattering by the electrons of a cluster
  with peculiar velocity

reionization at z20 (WMAP) damping of CMB
primary anisotropies Thomson scattering by the
electrons of the cosmic medium
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Components of the cosmic medium

• Electrons
• Molecules from primordial elements
• H2, H2, HD, HD, HeH, LiH, LiH,
• Atoms and ions of heavy elements
• CI, OI, SiI, SI, FeI
• CII, NII, NIII, SiII, FeII, FeIII, OIII

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Interaction process

• Thermal emission and absorption are negligible
• Elastic resonant scattering is the most promising
  process

sT6.65210-25 cm2
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Damping of primary anisotropies

• Optical depth
• Molecular density
• Cross section
• Redshift condition
• Angular condition

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Redshift condition
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Angular condition
obs
z1000
zres
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Molecular contribution to the optical depth
Damping is frequency dependent
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Observations with Planck
100 GHz
63µ OI line at z32
144 GHz 100 GHz
Basu et al. 2004
Foregrounds contamination
An observational frequency without resonant
scattering
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How to observe Dark Ages

• Lyman-a absorbers
• distant point source (QSO) absorption by HI
• depends on the optical depth and not on the
  distance

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How to observe Dark Ages

• CMB diffuse source scattering
• depends on the optical depth and not on the
  distance
• need of a peculiar velocity for the scattering
  source
• all sky background source

?p
Prim. cloud (zzres) ?0
CMB (z1100) ?obs ?0(1ßpcos?)
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Primordial Resonant Lines
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Line width and line shape of the PRL

• linear evolution
• turn-around
• spherical collapse

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Summary of PRL features
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Observational summary

• Frequency 10 - 800 GHz
• Angular scale 5" 2'
• Spectral resolution

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Observational results

• IRAM 30m few spots with a narrow band
• upper limits and a (false) detection

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Observational results

• ODIN few spots with a large band
• (see Hjalmarson talk)
• 31 GHz survey in 300 orbits
• upper limits 65 mK with 1 MHz resolution
• test of pattern recognition tools for future
  experiments
• HERSCHEL-HiFi many spots with a large band

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Conclusions

• PRLs are the most promising tool to observe Dark
  Ages and test the structure formation models
• very large bandwidth needed (satellites)
• easy to test cosmological origin (observation of
  two lines, search for main molecular lines at
  z0)
• no foregrounds contamination
• richness of information
• frequency ? chemical composition, redshift of the
  scattering source, abundance
• line shape ? dynamical environment
• two lines ? temperature
• diffuse background source ? size of the
  scattering source