The Gemini/HST Galaxy Cluster Project – Galaxy Evolution During Half the Age of the Universe Marcel Bergmann (NOAO Gemini Science Center) Inger Jørgensen, Gemini Jordi Barr, Oxford Roger Davies, Oxford Kathleen Flint, Gemini David Crampton, HIA Bryan Miller, Gemini Marianne Takamiya, UH-Hilo Abell 851 z=0.41

Science Objectives ● Star formation history in rich clusters of galaxies ● As a function of galaxy mass ● As a function of redshift ● Duration of star formation bursts; galactic winds; IMF variations ● Methods ● Scaling relations ● Fundamental Plane ● velocity dispersion – absorption line strengths ● With the use of models: Determine luminosity weighted mean ages, [M/H], [  /Fe]

Summary & Conclusions ● We are obtaining deep spectroscopy and HST imaging for 15 clusters covering 0.2 < z < 1.0 ● Offsets in the Faber-Jackson relation are inconsistent with passive evolution models having zf > 2 for Abell 851 and RXJ ● Line index analysis for RXJ suggests that the stellar populations in these galaxies are also inconsistent with passive evolution because the [E/Fe] abundance ratios evolve. ● More work is needed to produce models which can be applied to low and high z observations consistently. ● We may be seeing hints at environmental effects within the cluster on the stellar population element abundance ratios.

Selection of Clusters

RXJ RXJ Abell 851 Perseus Coma

Observational data for each cluster ● Gemini/GMOS imaging in 3 filters

Observational data for each cluster ● Gemini/GMOS imaging in 3 filters ● Gemini/GMOS spectroscopy – cluster members per cluster – 1-2 mag deeper than most previous studies – Higher S/N spectra – No morphological selection; blue galaxies included redshift, velocity dispersion: z, σ absorption line indices: Mgb,, Hβ (redshift, Hβ (redshift < 0.7) C4668, Fe4383, Hδ+H  γ (all redshifts) C4668, Fe4383, Hδ+H  γ (all redshifts) ● HST: ACS or WFPC2 imaging => 2D photometry, effective parameters, morphology

0.5 Mpc H 0 =70 km/s/Mpc  m =0.3  =0.7 Perseus z=0.018 RXJ z= arcsec 10 arcmin

Abell 851 z= arcmin 0.5 Mpc

Faber-Jackson Relation Faber-Jackson Relation Coma RXJ ∆m=-0.51±0.21 Abell 851 ∆m=-1.11±0.17 RXJ ∆m=-0.88±0.18 ∆log(age)=-0.37 z f = 4.1 ( )

Faber-Jackson Relation Faber-Jackson Relation Coma RXJ ∆m=-0.51±0.21 Abell 851 ∆m=-1.11±0.17 RXJ ∆m=-0.88±0.18 ∆log(age)=-0.37 z f = 4.1 ( ) RXJ0142 and Abell 851 are inconsistent with passive evolution models having z f > 2

Line Index- σ Relations Line Index- σ Relations

Line Indices & SSP Models Line Indices & SSP Models

RXJ (z=0.83) vs. z=0 RXJ (z=0.83) vs. z=0

Summary & Conclusions ● We are obtaining deep spectroscopy and HST imaging for 15 clusters covering 0.2 < z < 1.0 ● Offsets in the Faber-Jackson relation are inconsistent with passive evolution models having zf > 2 for Abell 851 and RXJ ● Line index analysis for RXJ suggests that the stellar populations in these galaxies are also inconsistent with passive evolution because the [E/Fe] abundance ratios evolve. ● More work is needed to produce models which can be applied to low and high z observations consistently. ● We may be seeing hints at environmental effects within the cluster on the stellar population element abundance ratios.

“Optical Line Indices” “Blue Line Indices”