WMAP Implications for Reionization Columbia University The Davis Meeting on Cosmic Inflation March, 2003 Zoltán Haiman

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

Outline of Talk 1. Theoretical Modeling of Reionization – what were the sources? – what are the key feedback processes? 2. Observational Signatures – distribution of neutral hydrogen – distribution of free electrons

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

What were the sources of reionization? Not a stringent energetic requirement eV (chemical) vs >MeV (nuclear or grav.) Non-linear structures are present early in most cosmologies (*)  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

Quasar space densityStar formation rate (Haiman, Abel & Madau 2001) log [d  * /dt/M  yr -1 Mpc -3 ] log [d  * /dt / M  yr -1 Mpc -3 ] log [n(z) / n(peak)] redshiftredshift Extra Stars or Quasars are Needed ZZ ??

Relevant Halo Mass Scales x 20 Jeans Mass 10 4 M ⊙ T vir =20 K x 20 TYPE II 17 H 2 cooling 10 5 M ⊙ T vir =10 2 K TYPE II 17 TYPE Ia 9 HI cooling 10 8 M ⊙ T vir =10 4 K TYPE Ia 9 TYPE Ib 5 Photo-heating M ⊙ T vir =2x10 5 K TYPE Ib 5 (masses at redshift z=10) 2  peak redshifts

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 ≳ Z ⊙ (Tumlinson & Shull 2001 ; Bromm, Kudritzki & Loeb 2001; Schaerer 2002) SEED BLACK HOLES: PERHAPS MASSIVE (~10 6 M ⊙ ) - boost by ~10 in number of ionizing photons/baryon - harder spectra up to hard X-rays - effects topology, IGM heating, H 2 chemistry - connections to quasars and remnant holes [especially z~6 super-massive BHs; also gravity waves] (Oh; Venkatesan & Shull; Haiman, Abel & Rees; Haiman & Menou)

Feedback Processes INTERNAL TO SOURCES - UV flux unbinds gas - supernova expels gas, sweeps up shells - H 2 chemistry (positive and negative) - metals enhance cooling - depends strongly on IMF GLOBAL - H 2 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) } 

First Global Feedback Soft UV background: H 2 dissociated by eV photons: “sawtooth spectrum” H 2 +   H 2 (*)  H+H+  ’ this background inevitable and it destroys molecules ~ 1 keV photons promote free electrons  more H 2 H+   H + +e - +  ’ H + e -  H - +  H - + H  H 2 + e - Soft X-ray background: this background from quasars promotes molecule formation ⊝⊕ Haiman, Abel & Rees (2000)

Second Global Feedback PHOTO-IONIZATION HEATING: - IGM temperature raised to ≳ 10 4 K - Gas in-fall suppressed in halos with velocity dispersion  ≲ 50 km/s - [or: Jeans mass increased…] 0D: Efstathiou D: Thoul & Weinberg D: Navarro & Steinmetz 1997

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

Outline of Talk 1. Theoretical Modeling of Reionization – what were the sources? – what are the key feedback processes? 2. Observational Signatures – distribution of neutral hydrogen – distribution of free electrons

“Percolation” is occurring at z~6-7 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) looking for hydrogen

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

Another Piece of Evidence for z r ≲ 10 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) Hui & Haiman (2003)

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

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

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

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

WMAP implications Complex reionization history required by WMAP + SDSS - significant activity at high redshift (“3  ” result) either : metal-free stars, mini-quasars with x60 “boost” or : H 2 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 H 2 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 x e (z) (Kaplinghat et al ; Holder et al. 2003) no ‘crisis’

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) Redshift xexexexe

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 ~ if of baryons in BHs, with 1% into heating - dust scattering with 0.3 M ⊙ dust per SN: y ~ improve FIRAS/COBE limit to …(?) (Fixsen & Mather 2002)

1. LCDM cosmogony naturally accommodates reionization 2. Different populations to satisfy both SDSS QSO + WMAP 3. Either H 2 formation or significant (x50) boost in efficiency 4. Future CMB observations will probe reionization history 5. Ly  Emitters and 21cm will probe neutral hydrogen 6. JWST will make direct detections to z=10 and beyond Conclusions & - - -

Le Fin