formation and evolution of early-type galaxies
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Formation and evolution of early-type galaxies. Pieter van Dokkum (Yale). Testing theories of galaxy formation. Early-type galaxies have highest halo/stellar masses: provide strong constraints on galaxy formation models or ?. - PowerPoint PPT PresentationTRANSCRIPT
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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 0<z<1.5
• Can be identified out to z~1.5 (ACS/z)
• Make up sizable fraction of “Extremely Red Objects”
Moustakaset al 2003
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Early-type galaxies at 0<z<1.5
• Can be identified out to z~1.5 (ACS/z)• Until recently, mostly studied in clusters
RXJ0848; z=1.27vD & Stanford 03
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Early-type galaxies at 0<z<1.5
• Can be identified out to z~1.5 (ACS/z)• Until recently, mostly studied in clusters• Studies of colors, line strengths, Fundamental
Plane: stars formed at high redshifte.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 0<z<1.5
• Can be identified out to z~1.5 (ACS/z)• Until recently, mostly studied in clusters• Studies of colors, line strengths, Fundamental
Plane: stars formed at high redshifte.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 03Models: Diaferio et al. 01
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Early-type galaxies at 0<z<1.5
• 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 z>2
(vD&Franx 01)
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• L* Sb/c galaxy at z=3: K 23, R 28• Would not be selected by any current method
Typical Lyman-break galaxyand typical nearby spiral
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Selecting optically-red z>2 galaxies
• Adopted criterion: J-K > 2.3– Models: selects galaxies at z > 2, ages larger
than ~500 Myr (in absense of dust)– Corresponds to U-V > 0.1 in the rest-frame for
galaxy at z = 3: would select most nearby gals
• Also expected:
– Dusty galaxies at z > 2 (enhances break)
– Extremely dusty galaxies at z < 2
Franx et al. 03, van Dokkum et al. 03, Daddi et al. 03
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FIRES – VLT+ISAAC176 hours J,H,K imaging
MS 1054-03Foerster-Schreiber et al. 045.4’ x 5.4’, seeing 0’’45
HDF SouthLabbe et al. 032.4’ x 2.4’, seeing 0’’45
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Optically-red galaxies at z>2
• Substantial surface density:~ 0.8/arcmin to K=21 (from both fields)~ 2/arcmin to K=22 (from HDF-S)~ 3/arcmin to K=23 (from HDF-S)
2
2
2
2
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Optically-red galaxies at z>2
• Substantial surface density: ~ 0.8/arcmin to K=21 (from both fields)~ 2/arcmin to K=22 (from HDF-S)~ 3/arcmin to K=23 (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 z>2
• Substantial surface density: ~ 0.8/arcmin to K=21 (from both fields)~ 2/arcmin to K=22 (from HDF-S)~ 3/arcmin to K=23 (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 z=2.43
Keck/NIRSPEC, 1½ hrsvD et al, ApJ, submitted
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Optically-red galaxies at z>2
• Substantial surface density: ~ 0.8/arcmin to K=21 (from both fields)~ 2/arcmin to K=22 (from HDF-S)~ 3/arcmin to K=23 (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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• Best constrained parameter: stellar (and dyn) mass
vD et al, ApJ, submitted
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Comparison to other star forming galaxies
LIRGSArmus et al 1989
normal nearby galaxiesJansen et al 2000
Solar
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Comparison to other star forming galaxies
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Correlations with linewidth
• Combining z=3 LBGs and z=2.6 ORGs: linewidth correlates with color and stellar mass
vD et al, ApJ, submitted
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Kinematics of massive galaxies at 0<z<3
vD et al, ApJ, submitted
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Kinematics of massive galaxies at 0<z<3
?
ERO
Early-type
ORG?
Spiral
LBG
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Kinematics of massive galaxies at 0<z<3
ERO
Early-type
ORG
Spiral
LBG
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Progenitors of early-type galaxies
• Substantial population of massive galaxies at z>2 with rest-optical colors similar to normal nearby galaxies
• Ideas have evolved rapidly .. not settled at all !– <1996: Radio galaxies, EROs– 1996: Lyman breaks– 2000: Scuba sources, hard X-ray sources– 2003: “K20” objects, ORGs (J-K>2.3)– 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 z=1.27– At z=3: requires NIR capability (J/H sufficient)– JWST too small