1. A hot topic: the 21cm line III Benedetta Ciardi MPA

2. o Differential brightness temperature o Maps are difficult to obtain  statistical quantities o Power spectrum: o Angular power spectrum: Some terminology & quantities

4. o Differential brightness temperature o Maps are difficult to obtain  statistical quantities o Power spectrum: o Angular power spectrum: Some terminology & quantities depends on e.g.: - underlying density distribution - ionized fraction - Lyalpha distribution - …

5. (Loeb & Zaldarriaga 2004) Absorption of CMB flux prior to structure formation  density structure Absorption prior to reionization (Loeb & Zaldarriaga 2004; Ali, Bharadwaj & Panday 2005; Barkana & Loeb 2005a; Pillepich, Porciani & Matarrese 2007; Lewis & Challinor 2007) Angular power spectrum

6. (Loeb & Zaldarriaga 2004) Absorption of CMB flux prior to structure formation  density structure Pb. Observations at frequencies <50MHz are extremely challenging Absorption prior to reionization Angular power spectrum

7. Atmospheric visibility T. Wilson Spitzer Hubble Chandra Compton GRO

8. (Loeb & Zaldarriaga 2004) Absorption of CMB flux prior to structure formation  density structure Pb. Observations at frequencies <50MHz are extremely challenging Absorption prior to reionization Angular power spectrum

9. If density fluctuations dominate 21cm fluctuations  cosmological parameters Determination of cosmological parameters McQuinn et al. 2006 Errors on cosmological parameter estimates at z=8

10. If density fluctuations dominate 21cm fluctuations  cosmological parameters Determination of cosmological parameters McQuinn et al. 2006 Errors on cosmological parameter estimates at z=8

11. If density fluctuations dominate 21cm fluctuations  cosmological parameters Determination of cosmological parameters McQuinn et al. 2006 Errors on cosmological parameter estimates at z=10, 12

12. Baryonic Acoustic Oscillations o Cosmological perturbations excite sound waves  acoustic peaks in CMB o Imprints also on the power spectrum of non relativistic matter  BAO Mao & Wu 2007 Pure baryons Pure CDM CMD + baryons z=6 Linear power spectrum Eistenstein & Hu 1998 Cooray & Sheth 2002

13. Baryonic Acoustic Oscillations o Cosmological perturbations excite sound waves  acoustic peaks in CMB o Imprints also on the power spectrum of non relativistic matter  BAO Mao & Wu 2007 Pure baryons Pure CDM CMD + baryons z=6 Linear power spectrum

14. Baryonic Acoustic Oscillations o Cosmological perturbations excite sound waves  acoustic peaks in CMB o Imprints also on the power spectrum of non relativistic matter  BAO o BAO has been observed in large galaxy surveys as SDSS and 2dF

15. BAO detection: galaxy surveys SDSS

16. BAO detection: galaxy surveys SDSS Eisentein et al. 2005 Cole et al. 2005 Ω m h²=0.12 0.13 0.14 no baryons

17. BAO detection: galaxy surveys 2dF

18. Baryonic Acoustic Oscillations o Cosmological perturbations excite sound waves  acoustic peaks in CMB o Imprints also on the power spectrum of non relativistic matter  BAO o BAO has been observed in large galaxy surveys as SDSS and 2dF o Measurements of BAO  information on cosmological parameters

19. BAO detection: 21cm observations Mao & Wu 2007 21cmA LOFAR o BAO signature on matter power spectrum  21cm power spectrum Mao & Wu 2007; Wyithe, Loeb & Geil 2007

20. BAO detection: 21cm observations o BAO signature on matter power spectrum  21cm power spectrum o 21cm galaxy survey

21. Gravitational lensing o Mass deflect light  multiple images, magnification, de-magnification, distortion

22. Gravitational lensing o Mass deflect light  multiple images, magnification, de-magnification, distortion Turner 2002

23. Gravitational lensing o Mass deflect light  multiple images, magnification, de-magnification, distortion NASA

24. Gravitational lensing o Mass deflect light  multiple images, magnification, de-magnification, distortion o If distortions very small  statistical analysis o Measurement of distortion  reconstruction of the foreground mass

25. Gravitational lensing o Mass deflect light  multiple images, magnification, de-magnification, distortion o If distortions very small  statistical analysis o Measurement of distortion  reconstruction of the foreground mass o Measurements of LSS weak lensing done with galaxies as background sources o Use NIRB, CMB or 21cm as background sources (Cooray 04; Pen 04; Zhan & Zaldarraiga 06; Lu & Pen 07) o Advantage of 21cm: many more sources, many more z

26. Gravitational lensing Metcalf & White 2007

27. Gravitational lensing Metcalf & White 2008

28. Gravitational lensing Hilbert, Metcalf & White 2007 20' HI sources at z=12 Spaced based gal. survey z med =1.23 Redshifts and virial masses

29. Hilbert, Metcalf & White 2007 No noise Noise HI sources Spaced based galaxy survey Ground based galaxy survey

30. Redshift Evolution of HI density z=18z=16z=14 z=12 z=13 z=11.5 z=10.5 z=9.5 z=9 z=10 z=8.5z=8 0.0 0.015 (BC, Stoehr & White 2003)

31. Maps of brightness temperature 13.5 8.79.3 9.910.611.3 12.012.8 8.1 K Distribution of (BC & Madau 2003)

32. Instrument sampling Instrument sensitivity Convolution with a Gaussian beam (  =3 arcmin) LOFAR-type telescope could be able to map the IGM reionization history & distinguish between reionization sources Expected response SimulatedSynthetic z=10.6, ν=122 MHz z=9.89, ν=130 MHz z=9.26, ν=138 MHz -2 -3 -4 -5 -1.4 -1.6 -1.8 -2.0 -2.2 -1.6 -1.8 -2.0 -2.2 -2.4 -1.6 -1.8 -2.0 -2.2 -2.4 -2.6 -2.8 Valdes et al. 2006

33. Observation of HII regions of high-z QSOs Wyithe, Loeb & Barnes 2005 Additional tool to study the IGM at z~6; estimate of n HI (Zaroubi & Silk 2005; Chen & Miralda-Escude' 2006; Cen 2006; Rhook & Haehnelt 2007; Liu et al. 2007)

34. Late Early  CMB anisotropies are produced by free electrons  21cm line is emitted by neutral hydrogen CMB/21cm line correlation Late Early

35. Characteristic angular scale of the cross-correlation function Late Early Mpc/h The characteristic angular scale of the cross-correlation function gives an estimate of the typical dimension of the HII regions at redshift of the 21cm emission line. CMB/21cm line correlation We find an anti-correlation below a characteristic angular scale, θ 0, when the correlation function becomes < 0. (Salvaterra et al. 2005; Alvarez et al. 2006; Holder et al. 2006; Adshead & Furlanetto 2007) Also correlation with galaxies?

36. Late Early (BC & Madau 2003) Fluctuations of brightness temp. l Late/Early reionization show similar behaviour l The peak of the emission is ~10 mK l Early reion. peaks @ 90MHz, late reion. peaks @ 115MHz Planned radio telescopes should be able to detect such signal (Madau et al. 1997; Ciardi & Madau 2003; Furlanetto et al. 2004; Zaldarriaga et al. 2004; Mellema et al. 2006; Santos et al. 2007)

37. Absorption features in high-z radio sources o Luminous radio source  21cm absorption features

38. Absorption features in high-z radio sources o Luminous radio source  21cm absorption features o DLAs

39. Absorption features in high-z radio sources DLAs

40. Absorption features in high-z radio sources o Luminous radio source  21cm absorption features o DLAs

41. Absorption features in high-z radio sources o Luminous radio source  21cm absorption features o DLAs o Proto-galactic disks and mini-halos

42. Absorption features in high-z radio sources Proto-galactic disks & mini-halos Furlanetto & Loeb 2002

43. Absorption features in high-z radio sources o Luminous radio source  21cm absorption features o DLAs o Proto-galactic disks and mini-halos

44. Absorption features in high-z radio sources o Luminous radio source  21cm absorption features o DLAs o Proto-galactic disks and mini-halos o IGM  21cm forest

45. Absorption features in high-z radio sources 21cm forest

46. IGM absorption from high-z radio source (Carilli, Gnedin & Owen 2002; Carilli et al. 2004) Additional information HI in the IGM (GRB's afterglow, Ioka & Meszaros 2004)

47. Absorption features in high-z radio sources o Luminous radio source  21cm absorption features o DLAs o Proto-galactic disks and mini-halos o IGM  21cm forest Pb. Are there bright enough sources of radio radiation at high-z?

48. High-z radio sources

49. Masers o Population inversion  masers statistical weight spin temperature

50. Masers o Population inversion  masers o A maser can boost the 21cm signal by order of magnitudes I(r) grows exponentially with r !!!

51. Masers o Population inversion  masers o A maser can boost the 21cm signal by order of magnitudes o

52. Masers o Population inversion  masers o A maser can boost the 21cm signal by order of magnitudes o If there are more photons with than with  maser! (Madau, Meiksin & Rees 1997)

53. Masers o Population inversion  masers o A maser can boost the 21cm signal by order of magnitudes o Dijkstra & Loeb 2007 Frequency shift: Doppler frequency width: Velocity dispersion:

54. Masers o Population inversion  masers o A maser can boost the 21cm signal by order of magnitudes o

55. SETI: Search for Extraterrestrial Intelligence o SETI program started in the '60s o Typically radio frequencies are scanned o Big Ear Observatory, Arecibo, Jodrell Bank… o Current programs could detect: - powerful beacons - transmissions with more typical power levels at distances < 1pc no star within 1pc from the Sun  no detection! Signals detectable by SKA Tarter (2001); Lazio et al. (2004)

56. o Power spectrum & cosmological parameters (BAOs, WL, 21cm from very high z…) o Map the evolution of HI in the IGM  reionization history & sources o Absorption studies of high-z radio sources Future 21cm observations