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Old and Massive Galaxies at z > 5 in the Galactic Zoo

Discover the population of evolved and massive galaxies at z > 5, including Lyman Break Galaxies, Lyman-a emitters, and submillimeter detected galaxies. Explore their characteristics and formation history.

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Old and Massive Galaxies at z > 5 in the Galactic Zoo

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  1. A Population of Old and Massive Galaxies at z > 5 T. Wiklind ESA/STScI B. Mobasher ESA/STScI, M. Dickinson NOAO, H. Ferguson STScI, M. Giavalisco STScI, N. Grogin JHU, N. Panagia STScI Galaxies and Structure Through Cosmic Times

  2. Evidence for evolved (age > 1 Gyr) and massive (M* > 1011 Mo) at z ~ 2 – 3 (many talks this meeting; posters: Kriek et al.) There are also evidence for galaxies of similar characteristics at z ~ 3 – 5 (this meeting; posters: Eyles et al.) • Members of the high-z galactic zoo • Lyman Break Galaxies (LBG) (z ~ 3-6) • Lyman-a emitters (LAE) (z ~ 4-6) • Submillimeter detected galaxies (SMG) (z ~ 2-3) • High-z AGNs (z ~ 6) • Old and massive galaxies (DRG) (z ~ 2-3) • Old and massive galaxies at z > 5 Galaxies and Structure Through Cosmic Times

  3. JD2 Galaxies and Structure Through Cosmic Times

  4. JD2 (J-dropout) in HUDF (see talk by Bahram Mobasher) z = 6.5 age ~ 0.65 - 1.0 Gyr EB-V = 0.0 M* = 5 1011 Mo Z ~ 0.2 Zo Galaxies and Structure Through Cosmic Times

  5. The Balmer break is a prominent feature for stellar populations age t > 100 Myrs z = 7 no extinction t = 50 Myr t = 100 Myr t = 300 Myr t = 500 Myr t = 600 Myr t = 800 Myr Galaxies and Structure Through Cosmic Times

  6. z = 5 • z = 8 • z = 5 • z = 8 • z = 2 • z = 4 Galaxies and Structure Through Cosmic Times

  7. There is no ‘clean’ way of color selecting old z > 5 galaxies Use a two-step process: • Color selection: • The main index is the Ks–3.6mm color • Use J–K and H–3.6mm as secondary color • This will result in a relatively large fraction of interlopers • Population synthesis models (Bruzual & Charlot 2003): • Redshift range z = 0.8 - 9.0 • Age range = 5 Myr - 2.4 Gyr • Calzetti extinction law EB-V = 0.0 - 1.0 • IGM absorption • Metallicities Z = 0.2, 0.4 1.0, 2.5 Zo • Salpeter IMF: 0.1 – 100 Mo • Star formation history: exponentially declining SFR t = 0 - 1.0 Gyr Galaxies and Structure Through Cosmic Times

  8. K-selected sample from GOODS-S HST/ACS (BViz); VLT/ISAAC (JHKs); SST/IRAC (3.6, 4.5, 5.8, 8mm) 5754 sources: 75 / 62 selected; 12/12 z > 5 (total 18) Galaxies and Structure Through Cosmic Times

  9. Galaxies and Structure Through Cosmic Times

  10. Galaxies and Structure Through Cosmic Times

  11. Best-fit parameters z = 5.1 EB-V = 0.0 age = 0.8 Gyr t = 0 Z = 0.4 Zo zform = 12 M* = 4 1011 Mo Galaxies and Structure Through Cosmic Times

  12. Best-fit parameters z = 6.1 EB-V = 0.025 age = 0.2 Gyr t = 0 Z = 0.2 Zo zform = 7 M* = 0.7 1011 Mo Galaxies and Structure Through Cosmic Times

  13. Not everything which is a J-band dropout is at z > 5 Galaxies and Structure Through Cosmic Times

  14. z = 2.6, EB-V = 0.2, age = 1.8 Gyr, t = 0.1, Z = Zo Galaxies and Structure Through Cosmic Times

  15. Galaxies and Structure Through Cosmic Times

  16. BBGs are very difficult to observe spectroscopically • No on-going star formation no strong line emission • Faint continuum absorption lines not possible We can test the method by applying it to objects with known redshift Galaxies and Structure Through Cosmic Times

  17. A total of 19 BBGs at z > 5 (including JD2) • Typical values: • Stellar masses ~ 3 1011 Mo • Ages 0.2 – 1.0 Gyr • Modest or no extinction • No on-going star formation • Formation redshift 9 – >25 • Less than half detected with MIPS at 24mm • Small systems (diameter ~ 4 kpc) • Not detected in X-rays / radio continuum • Number density 3–10 10-5 Mpc-3 Galaxies and Structure Through Cosmic Times

  18. A total of 19 BBGs at z > 5 (including JD2) • Typical values: • Stellar masses ~ 3 1011 Mo • Ages 0.2 – 1.0 Gyr • Modest or no extinction • No on-going star formation • Formation redshift 9 – >25 • Less than half detected with MIPS at 24mm • Small systems (diameter ~ 4 kpc) • Not detected in X-rays / radio continuum • Number density 3–10 10-5 Mpc-3 Thermally Pulsing AGB stars. Luminosity and time-scale at near-IR wavelengths? (Maraston this meeting) Galaxies and Structure Through Cosmic Times

  19. zspec = 5.83 zphot = 5.7 age = 1.0 Gyr log(M*) = 10.34 EB-V = 0.0 Z = 0.2 Zo zspec = 5.05 zphot = 4.8 age = 0.01 Gyr log(M*) = 8.53 EB-V = 0.0 Z = 0.2 Zo Models BC03. Data from Yan et al. 2005 Galaxies and Structure Through Cosmic Times

  20. zspec = 5.90 zphot = 5.8 age = 1.0 Gyr log(M*) = 10.49 EB-V = 0.0 Z = 1.0 Zo zspec = 4.65 zphot = 4.5 age = 0.4 Gyr log(M*) = 10.10 EB-V = 0.0 Z = 0.2 Zo Models BC03. Data from Yan et al. 2005 Galaxies and Structure Through Cosmic Times

  21. zspec = 4.78 zphot = 4.5 age = 0.7 Gyr log(M*) = 9.81 EB-V = 0.0 Z = 0.2 Zo zspec = 5.49 zphot = 4.8 age = 0.035 Gyr log(M*) = 9.56 EB-V = 0.10 Z = 0.2 Zo Models BC03. Data from Yan et al. 2005 Galaxies and Structure Through Cosmic Times

  22. z=0 galaxies M*>2.51010 MO M*>1.01011 MO LBGs K20 EROs BBGs sub-mm SDSS QSOs Somerville 2004 Galaxies and Structure Through Cosmic Times

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