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Briggs 2002

Epoch of Reionization: end of the dark ages. Briggs 2002. Evolution of the neutral IGM (Gnedin): ‘Cosmic Phase transition’. HI fraction. Ionizing intensity. density. Gas Temp. 6 Mpc. Recombination time vs. Hubble time. Cen 2002. CDM structure formation (PS). Efstathiou 1995.

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Briggs 2002

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  1. Epoch of Reionization: end of the dark ages Briggs 2002

  2. Evolution of the neutral IGM(Gnedin): ‘Cosmic Phase transition’ HI fraction Ionizing intensity density Gas Temp 6 Mpc

  3. Recombination time vs. Hubble time Cen 2002

  4. CDM structure formation (PS) Efstathiou 1995 N(1e11, z=6 – 8) = 3/arcmin^2 Note: M_BH = 0.006 M_spheroid

  5. Gunn-Peterson effect Barkana and Loeb 2001

  6. Discovery of the EOR?(Becker et al. 2002) Fast reionization at z= 6.3 => opaque at l_obs < 1 mm

  7. Lower limit to z_reio: GP Effect Fan et al. 2002 F(HI) > 0.01 at z = 6.3

  8. Upper limit to z_reio: CMB anisotropies Briggs

  9. Studying the IGM beyond the EOR: Ly alpha emission Hu et al 2002 Galaxy at z=6.56 Loeb-Rybicki halos

  10. Studying the IGM beyond the EOR: HI 21cm observations with the Square Kilometer Array and LOFAR t_21cm = 1e-8 t_Lya

  11. Temperatures: Spin, CMB, Kinetic and the 21cm signal Tozzi 2002 T_s T_CMB T_K • Initially T_S= T_CMB • T_S couples to T_K via Lya scattering • T_K = 0.026 (1+z)^2 (wo. heating) • T_CMB = 2.73 (1+z) • T_S = T_CMB => no signal • T_S = T_K < T_CMB => Absorption against CMB • T_S > T_CMB => Emission

  12. Global signature in wide field low frequency spectra(Shaver 1999)

  13. Imaging the neutral IGM at z=8.5(Tozzi 2002) Galaxies: 6uJy at 2’ res (= 20 mK) tCDM and OCDM 30 Mpc comoving QSOs: 3uJy/beam at 2’ res With and without soft Xray heating.

  14. Clustering of minihalos: T_vir < 1e4 K, M < 1e7 M_sun, d > 100 => no H line cooling => no star formation? (cf. Cen 2002) Iliev et al. 2002: 3sigma fluctuations due to statistical clustering 3sigma antenna fluctuations (Iliev et al. 2002)

  15. Difficulty with (LSS) emission observations: confusion by foreground radio sources (di Matteo 2001)

  16. Cosmic Webafter reionization = Ly alpha forest (d <= 10) 1422+23 z=3.62 Womble 1996 N(HI) = 1e13 -- 1e15 cm^-2, f(HI/HII) = 1e-5 -- 1e-6 => Before reionization N(HI) =1e18 – 1e21 cm^-2

  17. Cosmic Web before reionization: HI 21cm Forest Carilli, Gnedin, Owen 2002 • Mean optical depth (z = 10) = 1% = ‘Radio Gunn-Peterson effect’ • Narrow lines (1 to 10%, few km/s) = HI 21cm forest (d = 10)

  18. EOR: HI 21cm Absorption by the neutral IGM z = 8, 10,12

  19. Evolution of <temperatures> in the simulation

  20. Evolution of the neutral IGM z = 8 z = 12

  21. SKA observations of IGM absorption before the EOR A/T = 2000 m^2/K 240 hrs 1 kHz/channel z = 10 z = 8

  22. Detection limits Running rms: S_120 > 6 mJy in 240 hrs KS of noise: S_120 > 12mJy

  23. Absorption by minihalos (d > 100) (Furlanetto & Loeb 2002) N/Dz(minihalos) = N/Dz(IGM) = 10/unit z at z=8, t > 0.02

  24. Absorption in primordial disks toward GRBs N/Dz << minihalos and IGM (<1e-4x) but t>> minihalos and IGM (>50x) => Use much fainter radio sources (100 uJy): GRB afterglow within disk? Furlanetto & Loeb 2002 Barakana & Loeb 2000

  25. Radio sources beyond the EOR?

  26. Luminous radio sources at very high z Radio galaxy: 0924-220 z = 5.19 S_151 = 600 mJy Quasar: 0913+5821 z = 5.12 S_151 = 150 mJy M_BH = 1e9 M_sun 1” Van Breugel et al 1999 Petric et al. 2002

  27. Inverse Compton losses off the CMB = U_B (radio lobe)

  28. Radio sources beyond the EOR: sifting problem (1/1400 per 20 sq.deg.) USS samples (de Breuck et al.) 1.4e5 at z > 6 S_120 > 6mJy 2240 at z > 6

  29. Summary • Study of EOR (and beyond) and first luminous structures is next big challenge in observational cosmology. • GP effect => IGM opaque to observations at optical wavelengths => need longward of 1mm or shortward of soft Xray. • Study of neutral IGM: realm of low frequency radio astronomy. • Emission probes large scale structure. • Absorption probes intermediate to small scale structure (radio GP effect, HI 21cm forest, minihalos, proto-disks). • Constrain: z_reion, detailed structure formation, nature of first luminous sources, ionizing background, IGM heating and cooling. • LOFAR should provide first detections of the neutral IGM at z>6. • SKA will allow for detailed studies.

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