1. Life Before the Fall: Group Galaxy Evolution Prior to Cluster Assembly Anthony Gonzalez (Florida) Kim-Vy Tran (CfA) Michelle Conbere (Florida) Dennis Zaritsky (Arizona) John Moustakas (Arizona) Anthony Gonzalez (Florida) Kim-Vy Tran (CfA) Michelle Conbere (Florida) Dennis Zaritsky (Arizona) John Moustakas (Arizona)

2. Ringberg Workshop - October 25, 2005 Hierarchical Assembly: SG1120 Detection: Las Campanas Distant Cluster Survey (Gonzalez et al. 2001) 4 candidates at z~0.4 within a 7’ diameter region Confirmation: Chandra + spectroscopy 6 extended sources within a 13’ diameter region (~4 Mpc) Groups at z=0.37 (2,3,4,5) Cluster at z=0.48 (1) No redshift yet (6) “Supergroup” SG1120-1202 Detection: Las Campanas Distant Cluster Survey (Gonzalez et al. 2001) 4 candidates at z~0.4 within a 7’ diameter region Confirmation: Chandra + spectroscopy 6 extended sources within a 13’ diameter region (~4 Mpc) Groups at z=0.37 (2,3,4,5) Cluster at z=0.48 (1) No redshift yet (6) “Supergroup” SG1120-1202

3. Ringberg Workshop - October 25, 2005 Hierarchical Assembly: SG1120 VLT BVR Imaging VLT BVR Imaging 4 3

4. Ringberg Workshop - October 25, 2005 Spectroscopic Confirmation VLT Spectroscopy 101 confirmed members VLT Spectroscopy 101 confirmed members

5. Ringberg Workshop - October 25, 2005 Redshift Distribution Merging Galaxy Groups ``Virialized ’’ Halos Merging Galaxy Groups ``Virialized ’’ Halos Dispersions All620  50 km/s Group 3370  80 km/s Group 4450  80 km/s Group 5 560  90 km/s Dispersions All620  50 km/s Group 3370  80 km/s Group 4450  80 km/s Group 5 560  90 km/s Gonzalez et al. 2005

6. Ringberg Workshop - October 25, 2005 Mass and Dynamics Mass T x (sum of individual groups 2-5): 5x10 14 M  - lower limit Dynamical Analysis Gravitationally bound Should merge by z~0 Additional velocities for groups 2,6 will refine this constraint Should evolve in to a Coma-ish cluster by z=0 Mass T x (sum of individual groups 2-5): 5x10 14 M  - lower limit Dynamical Analysis Gravitationally bound Should merge by z~0 Additional velocities for groups 2,6 will refine this constraint Should evolve in to a Coma-ish cluster by z=0

7. Ringberg Workshop - October 25, 2005 Galaxy Evolution in Groups Coma Cluster (z ~ 0.02) SG1120 (z=0.37) Coma Progenitor

8. Ringberg Workshop - October 25, 2005 Galaxy Evolution in Groups Most of the action expected in groups (Zabludoff & Mulchaey, Kodama et al 2001, …) SG1120 offers a direct look at the progenitor of a massive z=0 cluster  Clean probe to quantify the degree of pre-processing Most of the action expected in groups (Zabludoff & Mulchaey, Kodama et al 2001, …) SG1120 offers a direct look at the progenitor of a massive z=0 cluster  Clean probe to quantify the degree of pre-processing

9. Ringberg Workshop - October 25, 2005 Galaxy Evolution in Groups Key Questions Morphological Evolution Quenched/Enhanced Star Formation E+A’s Fraction of star-forming galaxies; total star formation rate Galaxy Mass Assembly HOD Interaction Rate Wet/Dry Mergers Relation of above quantities to local density and galaxy mass Key Questions Morphological Evolution Quenched/Enhanced Star Formation E+A’s Fraction of star-forming galaxies; total star formation rate Galaxy Mass Assembly HOD Interaction Rate Wet/Dry Mergers Relation of above quantities to local density and galaxy mass

10. Ringberg Workshop - October 25, 2005 Galaxy Evolution in Groups Method Morphological Evolution (ACS - 10 orbit F814 mosaic) Quenched/Enhanced Star Formation E+A’s (VIMOS spectra, MIPS 24  m) Fraction of star-forming galaxies; total star formation rate Galaxy Mass Assembly (BVRJK S, ACS+WFPC2) HOD Interaction Rate Wet/Dry Mergers Relation of above quantities to local density and galaxy mass (Chandra, ACS, BVRJK s imaging, MIPS, spectroscopy) Method Morphological Evolution (ACS - 10 orbit F814 mosaic) Quenched/Enhanced Star Formation E+A’s (VIMOS spectra, MIPS 24  m) Fraction of star-forming galaxies; total star formation rate Galaxy Mass Assembly (BVRJK S, ACS+WFPC2) HOD Interaction Rate Wet/Dry Mergers Relation of above quantities to local density and galaxy mass (Chandra, ACS, BVRJK s imaging, MIPS, spectroscopy)

11. Ringberg Workshop - October 25, 2005 Color-Magnitude Diagram Established Red Envelope Retains Population of Starforming Galaxies Intermediate between Field/Clusters Established Red Envelope Retains Population of Starforming Galaxies Intermediate between Field/Clusters F Foreground/Background

12. Ringberg Workshop - October 25, 2005 Passive Fraction Pre-processing 61  8% passive - Roughly twice as many as field (same z)

13. Ringberg Workshop - October 25, 2005 Member Galaxies and Interactions

14. Ringberg Workshop - October 25, 2005 Summary SG1120 is a confirmed “supergroup” at z=0.37 Gravitationally bound system 4-5 member groups within target region Direct view of progenitors of massive cluster Well-defined red envelope Strong correlation between surface density and passive fraction Ongoing mergers of massive galaxies, high merger fraction SG1120 is a confirmed “supergroup” at z=0.37 Gravitationally bound system 4-5 member groups within target region Direct view of progenitors of massive cluster Well-defined red envelope Strong correlation between surface density and passive fraction Ongoing mergers of massive galaxies, high merger fraction

15. Ringberg Workshop - October 25, 2005 Work in Progress ACS Mosaic (10 orbit F814W) Morphological fractions and morphology-density relation Interaction rate MIPS - dusty star formation Additional spectroscopy E+A fraction Fundamental plane Finish mapping superstructure ACS+Chandra+spectra Cross-correlation between local density and X-ray surface brightness SED and morphology vs X-ray surface brightness Comparison with properties of both local clusters (Coma) and CL 1358 (z=0.33) ACS Mosaic (10 orbit F814W) Morphological fractions and morphology-density relation Interaction rate MIPS - dusty star formation Additional spectroscopy E+A fraction Fundamental plane Finish mapping superstructure ACS+Chandra+spectra Cross-correlation between local density and X-ray surface brightness SED and morphology vs X-ray surface brightness Comparison with properties of both local clusters (Coma) and CL 1358 (z=0.33)