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 ?

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” Moustakas et 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=1.27 vD & 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 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, …

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 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

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

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 galaxy and 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+ISAAC 176 hours J,H,K imaging MS Foerster-Schreiber et al ’ x 5.4’, seeing 0’’45 HDF South Labbe et al ’ 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

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

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 vD et al 03, Wuyts et al, in prep

Optically-red galaxy at z=2.43 Keck/NIRSPEC, 1½ hrs vD 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 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 LIRGS Armus et al 1989 normal nearby galaxies Jansen 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