Primordial Resonant Lines in the early universe

1. Primordial Resonant Lines in the early universe Roberto Maoli Univ. di Roma "La Sapienza" – IAP Paris

2. Pre-reionization Dark Ages Post-reionization Dark Ages Direct observation of the universe z=1100: CMB anisotropies Dark ages Reionization Structure formation z=5-10: first quasars z=0: today universe

3. 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 z=20 (WMAP) damping of CMB primary anisotropies Thomson scattering by the electrons of the cosmic medium

4. 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

5. Interaction process • Thermal emission and absorption are negligible • Elastic resonant scattering is the most promising process σT=6.652·10-25 cm2

6. Damping of primary anisotropies • Optical depth: • Molecular density: • Cross section: • Redshift condition: • Angular condition:

7. Redshift condition

8. Angular condition obs z=1000 zres

9. Molecular contribution to the optical depth Damping is frequency dependent

10. Observations with Planck 100 GHz 63μ OI line at z=32 144 GHz – 100 GHz Basu et al. 2004 Foregrounds contamination An observational frequency without resonant scattering

11. How to observe Dark Ages • Lyman-α absorbers distant point source (QSO) + absorption by HI depends on the optical depth and not on the distance

12. 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 (z=zres) ν0 CMB (z=1100) νobs= ν0(1+βpcosθ)

13. Primordial Resonant Lines

14. Line width and line shape of the PRL • linear evolution: • turn-around: • spherical collapse:

15. Summary of PRL features

16. Observational summary • Frequency: 10 - 800 GHz • Angular scale: 5" – 2' • Spectral resolution:

17. Observational results • IRAM 30m: few spots with a narrow band upper limits and a (false) detection

18. 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

19. 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 z=0) • 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