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Probing the Reionization Epoch in the GMT Era

Probing the Reionization Epoch in the GMT Era. Xiaohui Fan (University of Arizona) Seoul/GMT Meeting Oct 5, 2010. Probing Reionization History. Key Questions: When? - reionization redshift How? - uniform/patchy? topology What? - galaxies, AGN, other?. Two Key Constraints:

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Probing the Reionization Epoch in the GMT Era

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

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

  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 zreion = 7 Dunkely+ 2009, Komatsu+2010

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

  5. 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 • fHI ~ 0.3 - 0.6 at z~7 • Overlapping at z=6-7? z=6.96 Iye et al. 2006 Kashikawa et al. 2006 Ota et al. 2007, 2010

  6. GLARE survey of high-z Ly galaxies; 36hr integration with Gemini+GMOS[Stanway et al 2006] Simulated observation of z=6 Ly galaxy; 30hr with GMT+GMACS[McCarthy 2007] Ly- in high-z galaxies Ly flux (erg/cm2/s) Ly flux > 5x10-18 erg/cm2/s

  7. 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. Bland-Hawthorn J H K

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

  9. 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 Lyman- redshift Magellan 8hrs QSO @ z=9.4 F F GMT 8hrs X.Fan Wavelength (m) Probing the Neutral Era with ELT Quasar/GRB Spectroscopy

  10. 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

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

  12. 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 deg2: Y<24; 30 deg2: 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 deg2: JAB<21 • VISTA/VHS (2010+): 20000 deg2: JAB<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)

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

  14. 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

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

  16. 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

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