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L. Calcada/ESO

Spectroscopic confirmation of a galaxy at redshift z=8.6. M. D. Lehnert et al. 2010 Oct 21, Nature, 467, 940. 2010 Nov 4 Sang Chul KIM ( 김상철 ). L. Calcada/ESO. Distant Objects – Previous record holders. Galaxy z = 5.7 (Ajiki et al. 2003, AJ, 126, 2091)

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L. Calcada/ESO

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  1. Spectroscopic confirmation of a galaxy at redshift z=8.6 M. D. Lehnert et al. 2010 Oct 21, Nature, 467, 940 2010 Nov 4 Sang Chul KIM (김상철) L. Calcada/ESO

  2. Distant Objects – Previous record holders Galaxy z = 5.7 (Ajiki et al. 2003, AJ, 126, 2091) z = 5.74 (Hu et al. 1999, ApJ, 521, L9) z = 6.56 (Hu et al. 2002, ApJ, 568, L75) z = 6.6 (Taniguchi et al. 2005, PASJ, 57, 165) z = 6.96 (Iye et al. 2006, Nature, 443, 186) : 750Myr after the BB GRB z = 8.2 (GRB090423, Tanvir et al. 2009, Nature, 461, 1254) Iye et al. Nature, 443, 186

  3. Cosmic History Big Bang T = 300,000 yr Protons + electrons  neutral H, He Ionized fireball Gas cools Stars and galaxies Light up the Universe, heat up the gas and reionize it Reionization ended by z≈6 (1Gyr after the BB) Ionizing Lyman-α photons at more distant galaxies reionization : timing, location, nature of sources “reionization” era

  4. Discovery/Photometry of objects at z > 8 HST/WFC3/IR Hubble Ultra Deep Field (HUDF) Y105-dropout candidates 2.4” X 2.4” RA(J2000) = 03:32:38.13 DEC(J2000) = -27:45:53.9 Source intrinsic size : 0.3” Bouwens et al. 2010, ApJ, 709, L133

  5. VLT/SINFONI Observations of UDFy-38135539 8.2m Very Large Telescope (VLT) UT4 SINFONI – NIR Integral Field Unit (IFU: 3-dimensional) spectrograph 1.1 – 1.4 μm (J-band) Director’s Discretionary Time (program ID 283.A-5058)  16 hrs Texp =53400 s = 14.83 hr (integration time on the source, 600s each) R = λ/△λ =1580 (at λ~1.16μm), 190 km/s

  6. Telescope focus Spectrograph input Spectrograph output Pupil imagery Lenslet array Fibres slit Datacube Fibre array Image slicer Micro- mirrors slit y  x Anamo- rphism Micro- slicer Slicers retain spatial information along slice Main techniques of IFS (from J. Allington-Smith)

  7. HST/WFC3/IR • 1014 X 1014 px2 • 123” X 136”, 0.13”/px • Hubble Ultra Deep Field • (HUDF) • Center : RA(J2000) = 03:32:38.5 • DEC(J2000) = -27:47:0.0

  8. Emission line propertiesof UDFy-38135539 6σ significance detection of Lyman αemission line λobs= 11615.6 ±2.4 Å z = 8.5549 ± 0.0002 FWHM = 9.2 ± 1.2 Å Flux = (6.1± 1.0) X 10-18 erg cm-2 s-1 600 Myr after the BB

  9. Fig 2

  10. Alternative possibility • Another emission line at lower redshift (z = 2.12) • [O II] λ = 3726, 3729 Åemission doublet • [O II] doublet would be clearly resolved, intrinsically wider

  11. Luminosity - (1) • ΛCDM cosmology •  H0= 70 km/s/Mpc, ΩM=0.3, ΩΛ=0.7 • dl= 86.9 Gpc • total flux of Lyα emission  L = (5.5 ± 1.0 ± 1.8) X 1042 ergs-1 • (1σ uncertainty, systematic uncertainty) • Typical luminosities of currently known Lyα emitters in 3 < z < 7 : • L = (3-10) X 1042 ergs-1 without significant evolution • ∴ UDFy-38135539 : a typical Lyα emitting galaxy

  12. Luminosity – (2) Z = 8.55 : 1,700 Å UV  H160-band window H=28.1 mag  flux density of intrinsic luminosity density of continuum luminosity density : ~1mag fainter than MUV* ※ MUV* : characteristic magnitude of the UV luminosity function (LF) for galaxies with z = 6-7 Assuming LF evolution at z=3-7 applies up to z=8.6  UDFy-38135539 is a typical MUV* galaxy

  13. Stellar populations, SFR • Galaxies at lower redshift (z=5-7) : • seem age : very young (10 – 100 Myr) • metallicity : low • extinction : low • Assume for UDFy-38135539 : • low metallicity (0.1 Z⊙ – 0) • mass distribution : MF of massive stars in local galaxies or • with only very massive stars • age : 10 – 100 Myr (probably 300 Myr) • UV continuum luminosity  SFR = 2 - 4 M⊙ yr-1 • Lyα luminosity  0.3 – 2.1 M⊙ yr-1 • ※ lower limit if unknown absorption by intergalactic or IS medium

  14. Possible size of the ionized region around UDFy-38135539 Observing Lyα emission at z=8.55  surrounding intergalactic medium must be ionizied beyond ~1Mpc from the source Using total number of ionizing photons, SFR of UDFy-38135539 : ionized region radius : between and ※ : escape fraction of ionizing photons

  15. Fig 3 a

  16. Likely explanation for the relatively strong Lyα emission from UDFy-38135539 Other sources within a few Mpc may have contributed to ionizing the volume Luminous Lyα emission of UDFy-38135539  it is probably surrounded by other sources that contributed to the reionization of the Universe

  17. L. Calçada/ESO

  18. McLure et al. 2010, MNRAS, 403, 960

  19. McLure et al. 2010, MNRAS, 403, 960

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