The Gemini/HST Galaxy Cluster Project – The Gemini/HST Galaxy Cluster Project – Galaxy Evolution During Half the Age of the Galaxy Evolution During Half the Age of the

UniverseUniverse

Marcel BergmannMarcel Bergmann(NOAO Gemini Science Center)(NOAO Gemini Science Center)

Inger Jørgensen, GeminiJordi Barr, OxfordRoger Davies, OxfordKathleen Flint, GeminiDavid Crampton, HIABryan Miller, GeminiMarianne Takamiya, UH-Hilo

Abell 851 z=0.41

Science ObjectivesScience Objectives● Star formation history in rich clusters of Star formation history in rich clusters of

galaxiesgalaxies● As a function of galaxy massAs a function of galaxy mass● As a function of redshiftAs a function of redshift● Duration of star formation bursts; galactic Duration of star formation bursts; galactic

winds; IMF variationswinds; IMF variations● MethodsMethods

● Scaling relations Scaling relations ● Fundamental Plane Fundamental Plane ● velocity dispersion – absorption line velocity dispersion – absorption line

strengthsstrengths● With the use of models: Determine With the use of models: Determine

luminosity weighted mean ages, [M/H], [luminosity weighted mean ages, [M/H], [/Fe]/Fe]

Summary & ConclusionsSummary & Conclusions● We are obtaining deep spectroscopy and HST imaging for We are obtaining deep spectroscopy and HST imaging for

15 clusters covering 0.2 < z < 1.015 clusters covering 0.2 < z < 1.0● Offsets in the Faber-Jackson relation are inconsistent with Offsets in the Faber-Jackson relation are inconsistent with

passive evolution models having zf > 2 for Abell 851 and passive evolution models having zf > 2 for Abell 851 and RXJ0142.0+2131.RXJ0142.0+2131.

● Line index analysis for RXJ0152.7-1357 suggests that the Line index analysis for RXJ0152.7-1357 suggests that the stellar populations in these galaxies are also inconsistent stellar populations in these galaxies are also inconsistent with passive evolution because the [E/Fe] abundance with passive evolution because the [E/Fe] abundance ratios evolve.ratios evolve.

● More work is needed to produce models which can be More work is needed to produce models which can be applied to low and high z observations consistently.applied to low and high z observations consistently.

● We may be seeing hints at environmental effects within We may be seeing hints at environmental effects within the cluster on the stellar population element abundance the cluster on the stellar population element abundance ratios.ratios.

Selection of ClustersSelection of Clusters

Selection of ClustersSelection of Clusters

RXJ0152.7-1352 RXJ0142.0+2131 Abell 851

Perseus

Coma

Observational data for each clusterObservational data for each cluster

● Gemini/GMOS imaging in 3 filtersGemini/GMOS imaging in 3 filters

Observational data for each clusterObservational data for each cluster● Gemini/GMOS imaging in 3 filtersGemini/GMOS imaging in 3 filters● Gemini/GMOS spectroscopyGemini/GMOS spectroscopy

– 30-50 cluster members per cluster30-50 cluster members per cluster– 1-2 mag deeper than most previous studies1-2 mag deeper than most previous studies– Higher S/N spectraHigher S/N spectra– No morphological selection; blue galaxies No morphological selection; blue galaxies

includedincludedredshift, velocity dispersion: z, redshift, velocity dispersion: z, σσabsorption line indices: Mgb, <Fe>, Habsorption line indices: Mgb, <Fe>, Hββ (redshift < (redshift <

0.7)0.7) C4668, Fe4383, HC4668, Fe4383, Hδδ+H+Hγγ (all redshifts)(all redshifts)

● HST: ACS or WFPC2 imaging =>HST: ACS or WFPC2 imaging =>

2D photometry, effective parameters, 2D photometry, effective parameters, morphologymorphology

0.5 Mpc0.5 Mpc

H0=70 km/s/Mpc

m=0.3 =0.7

Perseus z=0.018

RXJ0152.7-1357 z=0.83

30 a

rcse

c

10 a

rcm

in

Abell 851 z=0.41

1 arcmin

0.5 Mpc

Faber-Jackson RelationFaber-Jackson Relation

•Coma

•RXJ0142.0+2131 ∆m=-0.51±0.21

•Abell 851 ∆m=-1.11±0.17

•RXJ0152.7-1357 ∆m=-0.88±0.18

∆log(age)=-0.37 zf = 4.1 (2.8 - 8.8)

Faber-Jackson RelationFaber-Jackson Relation

•Coma

•RXJ0142.0+2131 ∆m=-0.51±0.21

•Abell 851 ∆m=-1.11±0.17

•RXJ0152.7-1357 ∆m=-0.88±0.18

∆log(age)=-0.37 zf = 4.1 (2.8 - 8.8)

RXJ0142 and Abell 851 are inconsistent with passive evolution models having z

f > 2

Line Index-Line Index-σσ Relations Relations

Line Indices & SSP Line Indices & SSP ModelsModels

RXJ0152.7-1357 (z=0.83) vs. RXJ0152.7-1357 (z=0.83) vs. z=0z=0

Summary & ConclusionsSummary & Conclusions● We are obtaining deep spectroscopy and HST imaging for We are obtaining deep spectroscopy and HST imaging for

15 clusters covering 0.2 < z < 1.015 clusters covering 0.2 < z < 1.0● Offsets in the Faber-Jackson relation are inconsistent with Offsets in the Faber-Jackson relation are inconsistent with

passive evolution models having zf > 2 for Abell 851 and passive evolution models having zf > 2 for Abell 851 and RXJ0142.0+2131.RXJ0142.0+2131.

● Line index analysis for RXJ0152.7-1357 suggests that the Line index analysis for RXJ0152.7-1357 suggests that the stellar populations in these galaxies are also inconsistent stellar populations in these galaxies are also inconsistent with passive evolution because the [E/Fe] abundance with passive evolution because the [E/Fe] abundance ratios evolve.ratios evolve.

● More work is needed to produce models which can be More work is needed to produce models which can be applied to low and high z observations consistently.applied to low and high z observations consistently.

● We may be seeing hints at environmental effects within We may be seeing hints at environmental effects within the cluster on the stellar population element abundance the cluster on the stellar population element abundance ratios.ratios.

“Optical Line Indices”

“Blue Line Indices”