1. Probing the Reionization Epoch in the GMT Era Xiaohui Fan (University of Arizona) Seoul/GMT Meeting Oct 5, 2010

2. Probing Reionization History XF, Carilli & Keating 2006 Key Questions: When? - reionization redshift How? - uniform/patchy? topology What? - galaxies, AGN, other? Two Key Constraints: 1.WMAP 7-yr: z reion ~ 10 2. IGM transmission: z reion > 6

3. WMAP: early reionization? WMAP seventh-year: –  = 0.088+/- 0.014 z=10.5+/- 1.2 –Larger signal comparing to late reionization model (but marginally consistent!) However, no direct conflict to Gunn-Peterson result, which is sensitive only to ~1% neutral IGM Overlapping could still be at z~6 IGM could have complex reionization history  direct observation of high-z sources Dunkely+ 2009, Komatsu+2010 z reion = 7

5. Accelerated Evolution at z>5.7 Optical depth evolution accelerated –z<5.7:  ~ (1+z) 4.5 –z>5.7:  ~ (1+z) >11 –End of reionization? Evolution of neutral fraction –f HI > 10 -3 - 10 -2 at z=6 –Order of magnitude increase from z~5 –G-P absorption saturates; needs more sensitive tests (1+z) 4.5 (1+z) 11 XF et al. 2006

6. Iye et al. 2006 Kashikawa et al. 2006 Ota et al. 2007, 2010 Ly  Galaxy LF at z>6 Neutral IGM has extended GP damping wing  attenuates Ly  emission line Detectability of Ly  galaxies as markers of IGM optical depth –Reionization not completed by z~6.5 –f HI ~ 0.3 - 0.6 at z~7 –Overlapping at z=6-7? z=6.96

7. Ly-  in high-z galaxies GLARE survey of high-z Ly  galaxies; 36hr integration with Gemini+GMOS [Stanway et al 2006] Ly  flux > 5x10 -18 erg/cm 2 /s Simulated observation of z=6 Ly  galaxy; 30hr with GMT+GMACS [McCarthy 2007] Ly  flux (erg/cm 2 /s)

8. Ground-based Ly  surveys DAZEL - The Dark Age Z(redshift) Lyman-  Explorer on VLT: – dedicated Ly  narrow band survey instrument for z=7 - 10 – ~ 1 object per 10 hour field Keck blind spectroscopic survey along critical lines of high-z clusters –Six promising Ly  emitter candidates at z=8.7 - 10.2 –Large abundance of low-L galaxies; providing sufficient reionization photons –Limit of current search; New generation of OH suppression technique and AO: –Ground-based surveys could find Ly  emitters at z<12 Stark et al. J H K Bland-Hawthorn

9. Reionization Topology with Ly  Emitters Ly  emitter could provide sensitive probe to reionization history, especially during overlapping –Evolution of LF (constrain f HI ) –Clustering Distribution of Ly  emitters over 3’ FOV McQuinn et al. Neutral  Ionized

10. Probing the Neutral Era with ELT Quasar/GRB Spectroscopy QSO @ z=9.4Magellan 8hrs GMT 8hrs F Lyman-  redshift Wavelength (  m) X.Fan High S/N, moderate (R~5000) resolution spectroscopy of bright quasars/GRBs will allow determination of reionization, using –optical depth measurements –distribution of dark absorption troughs –sizes of quasar HII regions

11. Reionization with OI Absorption OI Forest (Oh 2002) –OI and H have almost identical ionization potentials –In charge exchange equilibrium with H but much lower abundance –Fluctuating OI forest during neutral era to probe ionization topology and metal pollution in the IGM OI system at z=6.26 Becker et al. 2006

12. Evolution of IGM Metals Early Enrichment of the IGM by First stars –First sign of rapid evolution at z~6 Ryan-Weber et al. Evolution of CIV systems IGM enrichment Signature of first stars Chemical feedback of earliest galaxies G. Becker

13. Next Generation Quasar Surveys Optical surveys: limited to z<7 New generations of red-sensitive CCD devices –Improved QE at 1 micron (Y band) –SUBARU/Princeton (2012+): a few hundred deg, Y<25;? –Pan-Starrs (2010+): 3  : Y<22.5; 1000 deg 2 : Y<24; 30 deg 2 : Y<26 –LSST (2017+): 3  : Y< 25 –Discovery of large number of quasars at z<7.5 New generation of Near-IR surveys: –UKIDSS (2005 - 2012?): 4000 deg 2: J AB <21 –VISTA/VHS (2010+): 20000 deg 2: J AB <21 –Discovery of a handful of quasars at z=7-9 Future Space Missions –WFIRST/ECULID (2020+) –JANUS (2015+) –Quasars up to z~10+ (assuming they existed)

14. Quest to the Highest Redshift 080913 050904 090423 000131 970228 GRBs

15. Probing Pop III Star Formation with He II Emission He II 1640A –High ionization potential –Results of metal-free star formation Deep HST observation of the highest redshift galaxy –Non-detections of HeII at z~7 –Pop III star formation < 0.3 solar mass/year Cai, XF+ 2010

16. Star-formation at z~10 Lyman  1216Å 20% escape fraction Star-forming region, z~10, GMT+GLAO, R=3000 filter, 8 hours He II 1640Å Salpeter IMF (ext. to 500M  ) Zero metals He II 1640Å Top-heavy IMF (300- 1000M  ) Zero metals

17. GMT For Reionization Epoch Highest redshift galaxies through Ly alpha –GMACS, NIRMOS Reionization history –Ly alpha galaxy mapping – GMACS, NIRMOS –GRBs and quasars – NIRMOS, GMTIFS –First metals in the IGM – NIROS, GMTIFS, GMTNIRS? First stars –HeII, signature of Pop.III – NIRMOS, GMTIFS –Extremely metal poor stars in the Galaxy – GMACS, G- CLEF, GMTNIRS