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WMAP Implications for Reionization

WMAP Implications for Reionization. Zolt á n Haiman. Columbia University. The Davis Meeting on Cosmic Inflation 22-25 March, 2003. Looking for Electrons with WMAP. [marginalized errors from TE correlation]. (Spergel et al. 2003). Z(reion)=6  0.04.

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WMAP Implications for Reionization

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  1. WMAP Implications for Reionization Zoltán Haiman Columbia University The Davis Meeting on Cosmic Inflation 22-25 March, 2003

  2. Looking for Electrons with WMAP [marginalized errors from TE correlation] (Spergel et al. 2003) Z(reion)=6  0.04

  3. Outline of Talk • Theoretical Modeling of Reionization –what were the sources? –what are the key feedback processes? • Observational Signatures – distribution of neutral hydrogen – distribution of free electrons

  4. The Dark Age (Chandra) Current horizon: z=6.6 Reionization: z 7-20 Recombination: z 1000

  5. What were the sources of reionization? • Not a stringent energetic requirement • - 13.6 eV (chemical) vs >MeV (nuclear or grav.) • Non-linear structures are present early in most cosmologies(*) • - 2-3 peaks above Jeans scale collapse at z=20-30 • Photo-ionization natural candidate • - consistent with Lyman  forest at lower z • - stars vs quasars • - decaying particles require fine-tuning of , m (*) Interesting exceptions

  6. Quasar space density Star formation rate log [n(z) / n(peak)] log [d* /dt/M yr-1 Mpc-3] redshift redshift (Haiman, Abel & Madau 2001) Extra Stars or Quasars are Needed 2 1 ? ? 0 -1 Z Z

  7. Relevant Halo Mass Scales (masses at redshift z=10) • Jeans Mass104 M⊙ Tvir=20 Kx 20 • H2 cooling105 M⊙ Tvir=102 K TYPE II 17 • HIcooling108 M⊙ Tvir=104 K TYPE Ia9 • Photo-heating1010 M⊙ Tvir=2x105 K TYPE Ib 5 2 peak redshifts

  8. What forms in these early halos? • STARS: FIRST GENERATION METAL FREE • - massive stars with harder spectra • - boost in ionizing photon rate by a factor of ~ 20 • - return to “normal” stellar pops at Z≳10-4 Z⊙ • (Tumlinson & Shull 2001 ; Bromm, Kudritzki & Loeb 2001; Schaerer 2002) • SEED BLACK HOLES: PERHAPS MASSIVE (~106 M⊙ ) • - boost by ~10 in number of ionizing photons/baryon • - harder spectra up to hard X-rays • - effects topology, IGM heating, H2 chemistry • - connections to quasars and remnant holes • [especially z~6 super-massive BHs; also gravity waves] • (Oh; Venkatesan & Shull; Haiman, Abel & Rees; Haiman & Menou)

  9. Feedback Processes } • INTERNAL TO SOURCES • - UV flux unbinds gas • - supernova expels gas, sweeps up shells • - H2 chemistry (positive and negative) • - metals enhance cooling • - depends strongly on IMF • GLOBAL • - H2 chemistry (positive and negative TYPE II) • - photo-evaporation (TYPE Ia) • - photo-heating (TYPE Ib) • - global dispersion of metals (pop III  pop II) • - mechanical (SN blast waves) 

  10. First Global Feedback Soft UV background: Soft X-ray background: this background inevitable and it destroys molecules this background from quasars promotes molecule formation ⊝ ⊕ H2 dissociated by 11.2-13.6 eV photons: ~ 1 keV photons promote free electrons  more H2 H2+ H2(*) H+H+’ H+  H++e-+’ “sawtooth spectrum” H + e- H- +  H-+ H  H2+ e- Haiman, Abel & Rees (2000)

  11. Second Global Feedback PHOTO-IONIZATION HEATING: - IGM temperature raised to ≳104K - Gas in-fall suppressed in halos with velocity dispersion  ≲ 50 km/s - [or: Jeans mass increased…] 0D: Efstathiou 1992 1D: Thoul & Weinberg 1995 3D: Navarro & Steinmetz 1997

  12. Reionization Histories (electron fraction) TYPE Ib TYPE Ia TYPE II (Haiman & Holder 2003)

  13. Outline of Talk • Theoretical Modeling of Reionization –what were the sources? –what are the key feedback processes? • Observational Signatures – distribution of neutral hydrogen – distribution of free electrons

  14. “Percolation” is occurring at z~6-7 looking for hydrogen • Spectra of z~6 quasars in SDSS • - Gunn-Peterson troughs at z > 6 • - Compared to HI opacity in 5.5 ≲ z ≲ 6 sources • (Becker et al. 2001; Fan et al. 2002, Songaila & Cowie 2002) • IGM Temperature • - IGM inferred to be warm from z~6 Lyman  forest • - It would be too cold for single early reionization • (Hui & Haiman 2003; Zaldarriaga et al. 1997; Theuns et al. 2002)

  15. Evolution of the Ionizing Background Fan et al. (2002) • Sharp drop at z~6 • Natural post-percolation • Difficult to explain otherwise • Similar conclusions in: • Lidz et al. 2002 • Cen & McDonald 2002 • Gnedin 2002 • Songaila & Cowie 2002 Ionizing background (10-12 s-1 ) redshift

  16. Another Piece of Evidence for zr ≲ 10 Hui & Haiman (2003) IGM quite warm at z~4 - measured T  20,000 K - adiabatic cooling vs. photo-ionization heating - requires a percolation at low redshift (z<10) (Zaldarriaga et al. 2001; Theuns et al. 2002)

  17. Reionization History Haiman & Holder 2003 0.08 0.08 electron fraction redshift redshift N=4000 f*=20% fesc=10% C=10 Wyithe & Loeb; Ciardi et al. Somerville et al.; Sokasian et al. Fukugita & Kawasaki; Cen Nf*fesc/C=8

  18. Reionization History Haiman & Holder 2003 TYPE II 0.17 0.08 electron fraction redshift redshift N=40000 f*=0.005 fesc=100% C=10 =20

  19. Reionization History Haiman & Holder 2003 0.17 TYPE II 0.17 TYPE Ia electron fraction redshift redshift N=40000 f*=0.005 fesc=100% C=10 N=40000 f*=20% fesc=10% C=3 =480 =20

  20. Reionization History Haiman & Holder 2003 Sudden Transition from a Metal Free to a Normal Stellar Population 0.17 electron fraction =8 for z<14 =160 for z>14 Wyithe & Loeb 2002 Cen 2002 redshift

  21. WMAP implications no ‘crisis’ • Complex reionization history required by WMAP + SDSS • - significant activity at high redshift (“3” result) • either : metal-free stars, mini-quasars with x60 “boost” • or : H2 molecules form efficiently in Type II halos • Some cosmogonies can be ruled out • - dark age = test-bed of small-scale P(k) • - WDM (~3? keV), Mixed DM (?) (Barkana, Haiman, Ostriker) • - Running Index (requires x 50 boost and H2 formation) • or x 3000 boost (Haiman & Holder 2003) • Future promise • - WMAP is sensitive only to  (total electron column) • - But if ≳0.1, then future EE/TE can distinguish xe(z) • (Kaplinghat et al. 2002 ; Holder et al. 2003)

  22. Future Polarization Measurements • Three reionization histories with same 0.16 • Different polarization power spectra • >4 in cosmic variance limit, ~3 for Planck • Can induce bias in  measurement (up to~0.02) Haiman & Holder (2003) xe Redshift

  23. Looking for Electrons in the CMB • CMB anisotropies • - damping of temperature anisotropy (geometrical) • - boosts large-angle polarization anisotropy (geom.) • - small scale SZ effect (energy)(l ≳ 3000; Oh et al. 2003) • Talks by M. Santos • and M. Kamionkowsky • Distortions of mean spectrum • - Compton heating: y=1/4 u/u ~ 10-5 • if 10-4 of baryons in BHs, with 1% into heating • - dust scattering with 0.3 M⊙ dust per SN: y ~ 10-5 • - improve FIRAS/COBE limit to 10-7 …(?) • (Fixsen & Mather 2002)

  24. Conclusions • LCDM cosmogony naturally accommodates reionization • Different populations to satisfy both SDSS QSO + WMAP • Either H2 formation or significant (x50) boost in efficiency • Future CMB observations will probe reionization history • Ly Emitters and 21cm will probe neutral hydrogen • JWST will make direct detections to z=10 and beyond - - - & - - -

  25. Le Fin

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