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Formation and evolution of early-type galaxies Pieter van Dokkum (Yale)

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 Presentation

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Page 1: Formation and evolution of early-type galaxies

Formation and evolution ofearly-type galaxies

Pieter van Dokkum (Yale)

Page 2: Formation and evolution of early-type galaxies

Testing theories of galaxy formation

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

or ?

Page 3: Formation and evolution of early-type galaxies

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

Page 4: Formation and evolution of early-type galaxies

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

Page 5: Formation and evolution of early-type galaxies

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, …

Page 6: Formation and evolution of early-type galaxies

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

Page 7: Formation and evolution of early-type galaxies

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

Page 8: Formation and evolution of early-type galaxies

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)

Page 9: Formation and evolution of early-type galaxies

• 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

Page 10: Formation and evolution of early-type galaxies

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

Page 11: Formation and evolution of early-type galaxies

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

Page 12: Formation and evolution of early-type galaxies

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

Page 13: Formation and evolution of early-type galaxies

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

Page 14: Formation and evolution of early-type galaxies

Foerster Schreiber et al., in prep

Page 15: Formation and evolution of early-type galaxies

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

Page 16: Formation and evolution of early-type galaxies

Optically-red galaxy at z=2.43

Keck/NIRSPEC, 1½ hrsvD et al, ApJ, submitted

Page 17: Formation and evolution of early-type galaxies

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

Page 18: Formation and evolution of early-type galaxies

• Best constrained parameter: stellar (and dyn) mass

vD et al, ApJ, submitted

Page 19: Formation and evolution of early-type galaxies

Comparison to other star forming galaxies

LIRGSArmus et al 1989

normal nearby galaxiesJansen et al 2000

Solar

Page 20: Formation and evolution of early-type galaxies

Comparison to other star forming galaxies

Page 21: Formation and evolution of early-type galaxies

Correlations with linewidth

• Combining z=3 LBGs and z=2.6 ORGs: linewidth correlates with color and stellar mass

vD et al, ApJ, submitted

Page 22: Formation and evolution of early-type galaxies

Kinematics of massive galaxies at 0<z<3

vD et al, ApJ, submitted

Page 23: Formation and evolution of early-type galaxies

Kinematics of massive galaxies at 0<z<3

?

ERO

Early-type

ORG?

Spiral

LBG

Page 24: Formation and evolution of early-type galaxies

Kinematics of massive galaxies at 0<z<3

ERO

Early-type

ORG

Spiral

LBG

Page 25: Formation and evolution of early-type galaxies

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

Page 26: Formation and evolution of early-type galaxies

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