A hot topic: the 21cm line III Benedetta Ciardi MPA
o Differential brightness temperature o Maps are difficult to obtain statistical quantities o Power spectrum: o Angular power spectrum: Some terminology & quantities
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 - …
(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
(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
Atmospheric visibility T. Wilson Spitzer Hubble Chandra Compton GRO
(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
If density fluctuations dominate 21cm fluctuations cosmological parameters Determination of cosmological parameters McQuinn et al Errors on cosmological parameter estimates at z=8
If density fluctuations dominate 21cm fluctuations cosmological parameters Determination of cosmological parameters McQuinn et al Errors on cosmological parameter estimates at z=8
If density fluctuations dominate 21cm fluctuations cosmological parameters Determination of cosmological parameters McQuinn et al Errors on cosmological parameter estimates at z=10, 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
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
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
BAO detection: galaxy surveys SDSS
BAO detection: galaxy surveys SDSS Eisentein et al Cole et al Ω m h²= no baryons
BAO detection: galaxy surveys 2dF
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
BAO detection: 21cm observations Mao & Wu cmA LOFAR o BAO signature on matter power spectrum 21cm power spectrum Mao & Wu 2007; Wyithe, Loeb & Geil 2007
BAO detection: 21cm observations o BAO signature on matter power spectrum 21cm power spectrum o 21cm galaxy survey
Gravitational lensing o Mass deflect light multiple images, magnification, de-magnification, distortion
Gravitational lensing o Mass deflect light multiple images, magnification, de-magnification, distortion Turner 2002
Gravitational lensing o Mass deflect light multiple images, magnification, de-magnification, distortion NASA
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
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
Gravitational lensing Metcalf & White 2007
Gravitational lensing Metcalf & White 2008
Gravitational lensing Hilbert, Metcalf & White ' HI sources at z=12 Spaced based gal. survey z med =1.23 Redshifts and virial masses
Hilbert, Metcalf & White 2007 No noise Noise HI sources Spaced based galaxy survey Ground based galaxy survey
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= (BC, Stoehr & White 2003)
Maps of brightness temperature K Distribution of (BC & Madau 2003)
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 Valdes et al. 2006
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)
Late Early CMB anisotropies are produced by free electrons 21cm line is emitted by neutral hydrogen CMB/21cm line correlation Late Early
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?
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. 90MHz, late reion. 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)
Absorption features in high-z radio sources o Luminous radio source 21cm absorption features
Absorption features in high-z radio sources o Luminous radio source 21cm absorption features o DLAs
Absorption features in high-z radio sources DLAs
Absorption features in high-z radio sources o Luminous radio source 21cm absorption features o DLAs
Absorption features in high-z radio sources o Luminous radio source 21cm absorption features o DLAs o Proto-galactic disks and mini-halos
Absorption features in high-z radio sources Proto-galactic disks & mini-halos Furlanetto & Loeb 2002
Absorption features in high-z radio sources o Luminous radio source 21cm absorption features o DLAs o Proto-galactic disks and mini-halos
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
Absorption features in high-z radio sources 21cm forest
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)
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?
High-z radio sources
Masers o Population inversion masers statistical weight spin temperature
Masers o Population inversion masers o A maser can boost the 21cm signal by order of magnitudes I(r) grows exponentially with r !!!
Masers o Population inversion masers o A maser can boost the 21cm signal by order of magnitudes o
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)
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:
Masers o Population inversion masers o A maser can boost the 21cm signal by order of magnitudes o
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)
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