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

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 ~ IGM transmission: z reion > 6

WMAP: early reionization? WMAP seventh-year: –  = / 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

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 > 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

Iye et al Kashikawa et al 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 ~ at z~7 –Overlapping at z=6-7? z=6.96

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

Ground-based Ly  surveys DAZEL - The Dark Age Z(redshift) Lyman-  Explorer on VLT: – dedicated Ly  narrow band survey instrument for z= – ~ 1 object per 10 hour field Keck blind spectroscopic survey along critical lines of high-z clusters –Six promising Ly  emitter candidates at z= –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

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

Probing the Neutral Era with ELT Quasar/GRB Spectroscopy 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

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

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

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 ( ?): 4000 deg 2: J AB <21 –VISTA/VHS (2010+): 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)

Quest to the Highest Redshift GRBs

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

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 ( M  ) Zero metals

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