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Downsizing & Galaxy Formation

Downsizing & Galaxy Formation. P. McCarthy OCIW. Gemini Deep Deep Survey Team. 2 nd Mitchell Symposium - April 2006. How are Galaxies Formed?. Monolithic Collapse ala ELS. Hierarchical Assembly . The Hierarchical Merger Tree. -----------------. Z = 3. ---------------. Z = 1.

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Downsizing & Galaxy Formation

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  1. Downsizing & Galaxy Formation P. McCarthy OCIW Gemini Deep Deep Survey Team 2nd Mitchell Symposium - April 2006

  2. How are Galaxies Formed? Monolithic Collapse ala ELS Hierarchical Assembly

  3. The Hierarchical Merger Tree ----------------- Z = 3 --------------- Z = 1 ------------- Z = 0

  4. Two Kinds of Galaxies Massive-Passive ------------------------------- BlueRed Light-Active 3 x 1010Msun Kauffmann et al 2003

  5. Star Formation History

  6. Mass Assembly History

  7. Gemini Deep Deep Survey Gemini GMOS spectrograph GMOSLRISLDSS1 30 hour exposures - 300+ redshifts I (Vega) ~ 24.5 1 < z < 2 Abraham, Glazebrook, PMcC, et al.

  8. Stellar Mass Determinations 100,000 Model Spectral Energy Distributions f(Age, SF history,abundance, reddening) + Observed Spectral Energy Distributions, Redshifts c2 Best-fit Template, range of templates MK X Best-fit M/L, range = Mstar, range

  9. The Most Massive Galaxies Glazebrook et al.

  10. Mass Downsizing L. Cowie 1996

  11. Three Views of Downsizing • Stellar Mass Density Evolution • Star Formation Histories by Mass • Early Assembly of Massive Galaxies

  12. Stellar Mass Density Cosmic Stellar mass density has not evolved at the high-mass end since z ~ 2

  13. The Evolving Stellar Mass Density

  14. New, improved semi-analytic models

  15. Star Formation Histories by Mass Massive Galaxies ceased star formation at z > 2, low mass galaxies continued active star formation to late epochs

  16. Star Formation Histories Juneau et al.

  17. Mass Downsizing

  18. Post Starburst Galaxies 50% Post-Star Burst @ z ~ 1.5 Only 1 in 10,000 galaxies in LCRS have similar EWs

  19. Early Assembly of Massive Galaxies 10% of today’s stellar mass was assembled into massive galaxies at z > 3, and 5% before z ~ 4.

  20. The Most Massive Galaxies ~ 20% z = 0 mass density Glazebrook et al.

  21. Spectral Types at z > 1.3 Star Forming Pure Passive

  22. Old Galaxies at 1.3 < z < 1.8 <z>=1.3

  23. Old Galaxies at 1.3 < z < 1.8 <z>=1.3 <z>=1.8

  24. Old Galaxies at 1.3 < z < 1.8 <z>=1.3 <z>=1.8 <z>=0.3

  25. Old Galaxies at 1.3 < z < 1.8 <z>=1.3 <z>=1.8 2Gyr Pegase Model

  26. Old Galaxies at 1.3 < z < 1.8 Age Fitting of 20 individual Galaxies 1.3 < z < 2.0 <zf> ~ 2.5 [Fe/H] > 0 E(B-V) ~ 1 <zf> ~ 4 [Fe/H] = 0

  27. Star Forming Galaxies 1.3 < z < 2.0 ACS F814W

  28. Pure Passive Systems ACS F814W NICMOS F160W 75-80% Spheroids

  29. Surface Brightness Profiles Z = 1.84 0.3 < Re< 1 Z = 1.32

  30. Size Distribution Little or no evolution in the size distribution

  31. Kormendy Relation at 1.3 < z < 2 Rest Frame V-Band Kormendy Diagram

  32. Kormendy Relation at 1.3 < z < 2 Passive Evolution ~1 mag per unit redshift

  33. “Old” Galaxies at z ~ 6 ~ 1/2 M* @ z ~ 10! Eyles et al. 2005

  34. 10 M*! Mobasher et al. 2005

  35. Basics ``Up-Sizing Giant Magellan Telescope 24m Aperture 18 x 18 VMOS 7 x 7 NIRMOS

  36. Conclusions • Galaxy Formation Proceeds from high to low masses • Some of today’s massive galaxies formed quite early • Good prospects for JWST and ELTs

  37. Wider or Deeper Surveys? Wider IMACS on the 6.5m Baade Telescope 27 Diameter field of view

  38. 350-500 slits per mask R ~ 1000 Nod & Shuffle sky subtraction

  39. Spectral Evolution Spectral Classes Passive Intermediate Composite Young

  40. Z = 0.1 Absorption Le Borgne et al. Emission M > 3 x 1010 Msun

  41. Z = 1.2 Absorption Le Borgne et al. Emission M > 3 x 1010 Msun

  42. Post-Starburst Galaxies Hd Strong Fraction M > 3 x 1010 Msun 50% of massive galaxies are post-starburst Systems at z ~ 1 !

  43. Massive Post Starburst Galaxies Intermediate Mass Galaxies had their star formation truncated at z ~ 1.5

  44. CIRSI + LCO Wide Field IR Camera du Pont 2.5m telescope 4 1024 x 1024 arrays cryogenic Offner relay 16 channel electronics Persson, Murphy, Birk

  45. Post-Starburst Galaxies 50% Post-Star Burst @ z ~ 1.5 Le Borgne et al.

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