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Outline of the lectures

Outline of the lectures. 1a. Introduction 1b. PopIII stars and galaxies --> « top down » theoretical approach 2.,3a. Ly  physics and astrophysics 3.b,4. Distant/primeval galaxies: - observational searches - current knowledge about high-z galaxies

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Outline of the lectures

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  1. Outline of the lectures 1a. Introduction 1b. PopIII stars and galaxies --> « top down » theoretical approach 2.,3a. Ly physics and astrophysics 3.b,4. Distant/primeval galaxies: - observational searches - current knowledge about high-z galaxies --> « bottom up » observational approach and confrontation with theory 1.

  2. Outline of Part 3b Distant/primeval galaxies - searches and main results Introduction + search methods Lya emitters (LAE) --> properties and key questions

  3. Quasars & galaxies + several « candidates/objects » at z~7 to 9 with photometric redshifts Galaxies Chemical elements… Tracers of cosmic history

  4. LALA survey z=4.5, 5.7, 6.6 VIMOS IFU Main search techniques for high-z galaxies • 1) Lyman break (drop-out technique) – • sensitive to overall broad-band • spectrum • 2) Emission line searches (Ly, …): • Narrow Band imaging (2D) • Long slit spectroscopy (1D) • Integral Field Units (3D) • Also: GRBs… • In deep fields or behind lensing clusters with • help of the « Gravitational Lensing » • z <~ 7: optical • z >~ 7: near-IR  ground-based, … JWST • z >~13-18: JWST only !

  5. Lya emitters (LAE)…mostly found through narrow-band (NB) searches z = 6.6 z = 5.7 z = 4.9 z ~ 7 Accessible “windows” from the ground

  6. Subaru Surveys forHigh-z Galaxies Some slides courtesy of Y. Taniguchi Yoshi Taniguchi

  7. The Subaru Deep Field (SDF) SDF: RA=13:24:38.9 DEC=+27:29.25.9 Sky Area = 875 arcmin2 Data release: see Kashikawa et al. 04, PASJ, 56, 1011

  8. Overview: LAEs @ z ~ 6.5-6.6 in SDF Selection criteria: z ’ – NB921 > 1.0 narrowband excess NB921 < 26.0 (5σ) significant NB detection i ’ – z ’ > 1.3 i-dropout • 58 candidates of LAEs @ z = 6.5 - 6.6 (photometric sample) • 17 LAEs @ z = 6.5 - 6.6 (LAE sample) Earlier spectroscopy: 9-14 out of 20 candidates confirmed (45-70%) (Taniguchi et al. 05; Kashikawa et al. 06)

  9. Overview: Spectroscopy of LAEs Spectroscopic follow-up of candidates Examination of Lya line profile: no evolution seen so far Hu et al. (2003) Hu et al. astro-ph/0509616

  10. Most Distant Galaxies @z > 6 No. Name z Tel. Method Ref. 1 SDF132522 6.597 Subaru NB Taniguchi05 2 SDF132520 6.596 Subaru NB Kashikawa06 3 SDF132357 6.589 Subaru NB Kashikawa06 4 SDF132432 6.580 Subaru NB Taniguchi05 5 SDF132528 6.578 Subaru NB Taniguchi05 6 SDF132418 6.578 Subaru NB Kodaira03 7 HCM-6A 6.56 Keck NB/GL Hu02 8 SDF132432 6.557 Subaru NB Kashikawa06 9 SDF132408 6.554 Subaru NB Taniguchi05 10 SDF132425 6.552 Subaru NB Kashikawa06 11 SEXSI-SER 6.545 Keck Ser Stern05 12 SDF132410 6.551 Subaru NB Kashikawa06 13 SDF132518 6.547 Subaru NB Kashikawa06 14 SDF132506 6.546 Subaru NB Kashikawa06

  11. No. Name z Tel. Method Ref. 15 SDF132415 6.542 Subaru NB Kodaira03 16 SDF132353 6.541 Subaru NB Taniguchi05 17 SDF132458 6.541 Subaru NB Kashikawa06 18 SDF132552 6.540 Subaru NB Taniguchi05 19 LALA142442 6.535 Keck NB Rhoads04 20 KCS 1166 6.518 VLT GRISM Kurk04 21 SDF132418 6.506 Subaru NB Taniguchi05 22 SDF132440 6.330 Subaru NB-D Nagao04 23 SDF132345 6.22 Subaru NB-D Nagao06 24 0226-04LAE 6.17 CFHT/VLT NB-D Cuby03 25 SDF132442 6.04 Subaru NB-D Nagao04 26 SDF132426 6.04 Subaru NB-D Nagao04 27 SDF132519 6.00 Subaru NB-D Nagao06 New LAEs from Hawaii14 LAEs @ z ~ 6.5, The highest-z = 6.74 (Hu, Cowie et al., astro-ph/0509616) Current record holder for spectroscopic redshift (Subaru)LAE @ z = 6.96 (Iye et al. 2006)

  12. The Most Distant LAE in SDF@ z = 6.96 Iye et al. 2006 (Nature)

  13. Cosmic Star Formation History • Taniguchi et al. (2005): • SFRD (LAE) ~ 0.01 x SFRD (LBG) • If corrections for • ・ Reddening (?) • 　・LF • =>SFRD (LAE) ~ 0.1 x SFRD (LBG) • BUT: No corrections for Lya • transmission (ISM and IGM)! • Two key results: • L emitters less significant than dropouts as contributors to SFR at z~6.6 • Yet an increasing fraction with increasing redshift (less evolution from z~3-6 than dropouts)

  14. MAHOROBA-11LAE to LBG Ratio @ z ~ 3 – 7 SDF SDF (Sumiya et al. 2006)

  15. Large Scale Structure @ z=5.7 via 515 Ly emitters Ouchi et al. (2005, ApJ, 620, L1)

  16. Schaerer (2003) LargeAreaLymanAlpha (LALA) survey * NB survey for Lya at z=4.5, 5.7 and 6.5 (Rhoads and collaborators). Widefield imaging on 4m telescope High median EW(Ly-a) found for z=4.5 sample ! ==> AGN ? Very-metal poor objects or Pop III ? Extreme (“top-heavy”) IMFs ? Puzzling nature ! Malhotra & Rhoads (2002)

  17. LALA survey - followup Fraction of LAE confirmed spectroscopically (e.g. ~70 % of 25) Some high EW(Lya) also confirmed spectroscopically (but aperture effects?) Objects with highest EW(Lya) have largest uncertainties (continumm faint or non-detected) Also : other groups do not find high EW objects ! (Hu et al. 2004, Ajiki et al. 2004) --> Photometry not deep enough ?! Rhoads et al. (2004) Dawson et al. (2004)

  18. LALA survey - followup Narrow lined AGN ? No: X-ray non-detections (individually and stacked) (Wang et al.) PopIII ?NO INDICATION so far. HeII non-detection (HeII/Lya < 13-20 % (2-3 sigma) and EW(HeII) < 17-25 Ang) Wang et al. (2004) Dawson et al. (2004)

  19. Stellar pops. + dust in LAE: an examle Lensed galaxy in Abell 370 HCM 6A, z=6.56 (Hu et al. 2002) • NB excess • asymetric emission line (Lya) • no secondary image • magnification 4.5

  20. SPITZER/IRAC sensitivity Prediction: IRAC/SPITZER (non detection) could confirm strong extinction Interpretation confirmed by Spiter detection (Chary et al. 2005) LAE: Abell 370 HCM 6A, z=6.56 Observations:BVRIZJHK (Keck, SUBARU), Lyα emission Main results from spectral fitting: * Best fits with burst models: age ~ 100-200 Myr, ~no extinction -- BUT no Ly emission expected then ! * Similarly good fits with SFR=const + non negligible extinction (AV~1.) Presence of dust in galaxy at z>6!  SFR ~ 11-41 Msun/yr (for 0.1-100 Salpeter: 28-115 Msun/yr cf. Hu et al.: 9 Msun/yr)  L~(1-4)*1011 Lsun (LIRG !?)  M* ~(1-4)*108 Msun No indication on metallicity  Ly transmission ~ 23-90% (Hu+Haiman 2002: ~20%) Schaerer & Pelló (2005)

  21. Properties of 3 LAE at z=5.7 GOODS-N field. Selected from NB imaging + spectroscopic confirmation. 3 objects detected in Spitzer bands. Lai et al. (2006, astro-ph/0610572): Degenerate SED fits in age, extinction, metallicity and SFH Ages up to 700 Myr! Most solutions require some dust extinction • Including need for Lya • emission: --> probably • SFR=const and • EB-V~0.1 - 0.2 • BUT: probably not • representative of LAE • population (IRAC selected!)

  22. Summary Part 3b Properties of LAE • Some objects with high EW(Lya) (LALA survey) • PopIII, AGN, strange IMF ? • Not AGN (X-rays) • HeII (PopIII signature) not detected • little information on overall SED and stellar pops. • - no/little dust ? But possible exceptions known • SFRD(Lya) < SFRD(UV)! Decline of SFRD above z>~5-7 !? But transfer+IGM+ effects? • Fraction of LAE/LBG increases with z • Nature ? Relation between LAE and other galaxies?

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