Rest-Frame near-IR Luminosity Evolution of Early-

Type Galaxies

Arjen van der Wel – JHU Baltimore

Marijn Franx - LeidenPieter van Dokkum - YaleJiasheng Huang - HarvardHans-Walter Rix - MPIAGarth Illingworth - UCSCStijn Wuyts - Leiden

- The optical FP at z~1 in the CDFS

- IRAC GTO observations

- Rest-frame near-IR L-evolution

- Optical and near-IR colors and M/L: observations and models

Redshift/magnitude/color/morphology selection

GOODS ACS imaging (Giavalisco et al. 2004);COMBO-17 photo-z’s (Wolf et al. 2003);Coleman et al. 1980 template spectra

All: Δ ln (M/LB) / z = ( -1.66 +/- 0.08 )

M > 2 ∙1011 Msun:Δ ln (M/LB) / z = ( -1.15 +/- 0.12 )

M vs. M/L of distant field galaxies

- Massive early-types evolve slowly, independent of environment

- Early-type galaxies show mass-dependent luminosity evolution.

- We do not have an un-biased view on evolution of L* early-types because of selection effects.

GTO IRAC data- 500s exposures

- PSF matchingACS, ISAAC (from ESO), IRAC data

- rest-frame B-through-K band colors

- comparison with local FP sampe (Pahre et al. 1998)

rest-frame K-band luminosity evolution

Evolution of M/LK

Δ ln ( M/LK ) / z = -1.18 +/- 0.10

Δ ln ( M/LB ) / z = -1.46 +/- 0.09

Evolution in B vs. Evolution in K

Top-Heavy IMF?

Dusty, young populations?

Conclusions

- K-band L-evolution: 1.3 mag at z=1

- K-band luminosity is not a mass indicator

- Bruzual & Charlot (2003) model:Problems in the near-IR

- Maraston (2005) model:Problems in the optical