Upload
ita
View
24
Download
0
Embed Size (px)
DESCRIPTION
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
Citation preview
Formation and evolution ofearly-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 ?
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
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
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, …
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
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
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)
• 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
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
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
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
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
Foerster Schreiber et al., in prep
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
Optically-red galaxy at z=2.43
Keck/NIRSPEC, 1½ hrsvD et al, ApJ, submitted
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
• Best constrained parameter: stellar (and dyn) mass
vD et al, ApJ, submitted
Comparison to other star forming galaxies
LIRGSArmus et al 1989
normal nearby galaxiesJansen et al 2000
Solar
Comparison to other star forming 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
Kinematics of massive galaxies at 0<z<3
vD et al, ApJ, submitted
Kinematics of massive galaxies at 0<z<3
?
ERO
Early-type
ORG?
Spiral
LBG
Kinematics of massive galaxies at 0<z<3
ERO
Early-type
ORG
Spiral
LBG
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
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