Formation and evolution of early-type galaxies

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Formation and evolution ofearly-type galaxies

• Pieter van Dokkum (Yale)

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Testing theories of galaxy formation

• Early-type galaxies have highest halo/stellar
  masses provide strong constraints on galaxy
  formation models
• or
  ?

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Early-type galaxies at 0ltzlt1.5

• Can be identified out to z1.5 (ACS/z)
• Make up sizable fraction of Extremely Red
  Objects

Moustakas et al 2003
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Early-type galaxies at 0ltzlt1.5

• Can be identified out to z1.5 (ACS/z)
• Until recently, mostly studied in clusters

RXJ0848 z1.27 vD Stanford 03
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Early-type galaxies at 0ltzlt1.5

• Can be identified out to z1.5 (ACS/z)
• Until recently, mostly studied in clusters
• Studies of colors, line strengths, Fundamental
  Plane stars formed at high redshift
• e.g., Ellis et al. 1997, Bernardi et al 98,
  Stanford et al 95/98, van Dokkum et al 98,01,
  Treu et al 99,02,

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Early-type galaxies at 0ltzlt1.5

• Can be identified out to z1.5 (ACS/z)
• Until recently, mostly studied in clusters
• Studies of colors, line strengths, Fundamental
  Plane stars formed at high redshift
• e.g., Ellis et al. 1997, Bernardi et al 98,
  Stanford et al 95/98, van Dokkum et al 98,01,
  Treu et al 99,02,
• Only small differences between field and cluster
  galaxies contrary to expectations

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Cluster versus field early-types
Datapoints vD et al 98,01, vD Ellis 03 see
also Treu et al 99,02 van der
Wel et al 03 Models Diaferio et al. 01
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Early-type galaxies at 0ltzlt1.5

• Remarkable agreement observationally early-type
  galaxies seem to have formed very early
• Caveats
• Results depend on IMF, metallicity, models
• Progenitor bias may miss youngest progenitors
• Assembly time may be (much) later than mean star
  formation epoch
• Solution look for massive galaxies at zgt2

(vDFranx 01)
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• L Sb/c galaxy at z3 K ? 23, R ? 28
• Would not be selected by any current method

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Selecting optically-red zgt2 galaxies

• Adopted criterion J-K gt 2.3
• Models selects galaxies at z gt 2, ages larger
  than 500 Myr (in absense of dust)
• Corresponds to U-V gt 0.1 in the rest-frame for
  galaxy at z 3 would select most nearby gals
• Also expected
• Dusty galaxies at z gt 2 (enhances break)
• Extremely dusty galaxies at z lt 2

Franx et al. 03, van Dokkum et al. 03, Daddi et
al. 03
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FIRES VLTISAAC 176 hours J,H,K imaging
MS 1054-03 Foerster-Schreiber et al. 04 5.4 x
5.4, seeing 045
HDF South Labbe et al. 03 2.4 x 2.4, seeing
045
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Optically-red galaxies at zgt2
2

• Substantial surface density
• 0.8/arcmin to K21 (from both fields)
• 2/arcmin to K22 (from HDF-S)
• 3/arcmin to K23 (from HDF-S)

2 2 2
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Optically-red galaxies at zgt2

• Substantial surface density
• 0.8/arcmin to K21 (from both fields)
• 2/arcmin to K22 (from HDF-S)
• 3/arcmin to K23 (from HDF-S)
• SEDs very different from Lyman breaks

2 2 2
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Foerster Schreiber et al., in prep
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Optically-red galaxies at zgt2

• Substantial surface density
• 0.8/arcmin to K21 (from both fields)
• 2/arcmin to K22 (from HDF-S)
• 3/arcmin to K23 (from HDF-S)
• SEDs very different from Lyman breaks
• Spectroscopic redshifts tough - 11 so far

2 2 2
vD et al 03, Wuyts et al, in prep
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Optically-red galaxy at z2.43
Keck/NIRSPEC, 1½ hrs vD et al, ApJ, submitted
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Optically-red galaxies at zgt2

• Substantial surface density
• 0.8/arcmin to K21 (from both fields)
• 2/arcmin to K22 (from HDF-S)
• 3/arcmin to K23 (from HDF-S)
• SEDs very different from Lyman breaks
• Spectroscopic redshifts for 11 so far
• Rest-frame optical spectroscopy SED fits
  massive, dusty, star-forming galaxies

2 2 2
vD et al 03, Wuyts et al, in prep
vD et al, ApJ, submitted Foerster Schreiber et
al, in prep
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vD et al, ApJ, submitted

• Best constrained parameter stellar (and dyn) mass

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Comparison to other star forming galaxies
LIRGS Armus et al 1989
normal nearby galaxies Jansen et al 2000
Solar
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Comparison to other star forming galaxies
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Correlations with linewidth

• Combining z3 LBGs and z2.6 ORGs linewidth
  correlates with color and stellar mass

vD et al, ApJ, submitted
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Kinematics of massive galaxies at 0ltzlt3
vD et al, ApJ, submitted
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Kinematics of massive galaxies at 0ltzlt3
Early-type
?
ERO
ORG
?
Spiral
LBG
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Kinematics of massive galaxies at 0ltzlt3
Early-type
ERO
ORG
Spiral
LBG
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Progenitors of early-type galaxies

• Substantial population of massive galaxies at zgt2
  with rest-optical colors similar to normal nearby
  galaxies
• Ideas have evolved rapidly .. not settled at all
  !
• lt1996 Radio galaxies, EROs
• 1996 Lyman breaks
• 2000 Scuba sources, hard X-ray sources
• 2003 K20 objects, ORGs (J-Kgt2.3)
• 2004 Gemini Deep Deep Field galaxies

Franx et al 03, vD et al 03,04, Daddi et al 03,
Foerster Schreiber et al 04
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Progenitors of early-type galaxies

• Galaxies have optical breaks, and probably
  familiar metal lines in their rest-optical
  spectra
• Absorption line studies stellar kinematics,
  masses
• Presence of dynamically cold hot components
• Diagnostics of stellar populations
• Not possible with current instruments/telescopes
• Keck 12 hrs to measure kinematics at z1.27
• At z3 requires NIR capability (J/H sufficient)
• JWST too small