1. すばるが見た遠方銀河団 distant clusters of galaxies: take a closer look Masayuki Tanaka (University of Tokyo) Tadayuki Kodama (NAOJ) + PISCES team picture credits: Sloan Digital Sky Survey, Robert Lupton (Princeton)

2. Outline 1 – Introduction 1-1 Environmental Dependence of Galaxy Properties 2 – Large-Scale Structures at z<1.2 2-1 Observational Data 2-2 Large-Scale Structures 3 – The Build-up of the Color-Magnitude Relation 3-1 Definitions of Environments 3-2 Color-Magnitude Diagrams 4 – Summary

3. 1-1 Environmental Dependence of Galaxy Properties cluster galaxies field galaxies environment galaxy density

4. Galaxies in low-density environments NGC5668

5. Galaxies in high-density environments Coma cluster

6. The environmental dependence of galay morphology was first quantified by Dressler 1980 (ApJ, 236, 351) Morphology-Density Relation galaxy densityhigh low population fraction S0 E Sp + Irr

7. SFR-Density + Morph.-Density Rels Revisited Tanaka et al. 2004 AJ, 128, 2677 Based on a large sample of SDSS galaxies, we revisited the SFR-density and morphology-density relations. Galaxies with different luminosity have different dependence on environment. Mr < Mr* + 1 Mr* + 1 < Mr < Mr* + 2

8. PISCES Project - is a systematic survey of galaxy clusters at 0.4<z<1.2 Kodama et al. 2005, PASJ, 57, 309

9. Outline 1 – Introduction 1-1 Environmental Dependence of Galaxy Properties 2 – Large-Scale Structures at z<1.2 2-1 Observational Data 2-2 Large-Scale Structures 3 – The Build-up of the Color-Magnitude Relation 3-1 Definitions of Environments 3-2 Color-Magnitude Diagrams 4 – Summary

10. 2-1 Observational Data Mauna Kea Observatories

11. redshift z=0 z=1.24 (8.6Gyr) z=0.55 (5.4Gyr) z=0.83 (7.0Gyr) Source Photometry Spectroscopy Sloan Digital Sky Survey u g r i z ~260,000 objects (DR2) Suprime-Cam (Subaru) B V R i z FOCAS (Subaru) ~200 objects Suprime-Cam (Subaru) V R i z FOCAS (Subaru) ~300 objects Suprime-Cam (Subaru) V R i z WFCAM (UKIRT) K CL0016+16 RXJ0152 RDCS1252

12. Photometric Redshifts CL0016 @ z=0.55RXJ0152 @ z=0.83 idea: galaxies at different redshifts have different observed colors.

13. How accurate is it?

14. 2-2 Large-Scale Structures Mauna Kea Observatories

15. CL0016 at z=0.55 ACS/ HST Color composition by Ichi Tanaka

16. Large-Scale Structures CL0016 at z=0.55

17. Large-Scale Structures CL0016 at z=0.55 real structures! Hoshi et al. in prep.

18. RXJ0153 at z=0.83 Color composition by Ichi Tanaka

19. Large-Scale Structures RXJ0152 at z=0.83

20. Large-Scale Structures RXJ0152 at z=0.83

21. Large-Scale Structures RXJ0152 at z=0.83 z=0.844 z=0.842 z=0.745 z=0.782 z=0.835 z=0.837 z=0.839 z=0.844

22. RDCS1252 at z=1.24

23. Large-Scale Structures RDCS1252 at z=1.24

24. Outline 1 – Introduction 1-1 Environmental Dependence of Galaxy Properties 2 – Large-Scale Structures at z<1.2 2-1 Observational Data 2-2 Large-Scale Structures 3 – The Build-up of the Color-Magnitude Relation 3-1 Definitions of Environments 3-2 Color-Magnitude Diagrams 4 – Summary

25. 3-1 Definition of Environments RDCS1252 (z=1.24) is not used from now on.

26. Local / Global Density local density + global density (nearest-neighbor density) (density within r=2Mpc aperture) Field :  local <  break Group :  local >  break +  global <  break Cluster ：  local >  break +  global >  break

27. Cluster / Group / Field Environments redshift z=0 z=0.55 z=0.83

28. Fast Facts galaxy-galaxy mergers <1Gyr strong field/group harassment ? strong cluster ram-pressure stripping <1Gyr weak cluster strangulation ~1Gyr weak group/cluster mechanisms star formation morphology effective env.

29. 2-4 Colour-Magnitude Diagrams Mass Time Galaxy Colours Environment

30. Colour-Magnitude Diagrams red blue z=0 z=0.55 z=0.83 redshift massive less massive

31. Colour Dispersion around CMR z=0.83 z=0.55 z=0

32. Giant-to-Dwarf ratio z=0.8 z=0.5 z=0

33. Colour-Magnitude Diagrams red blue z=0 z=0.55 z=0.83 redshift massive less massive 2) 'Down-sizing' is delayed in low-density environments. 1) Galaxies follow the 'down-sizing' evolution.

34. 3.3 – Spectral Diagnostics

35. Composite Spectra of Red Galaxies

36. D4000 and Hd D4000 Hd

37. D4000 and Hd D4000 Hd D4000 monotonically changes with time. Hd shows a peak after 0.1 – 1 Gyr of the last episode of star formation.

38. Model Star Formation Histories time star formation rate SSP model tau model burst model Bruzual & Charlot 2003 Model : Chabrier IMF between 0.1-100Msolar Solar Metallicity, No dust extinction

39. Spectral Diagnostics – SSP model grids: Bruzual & Charlot 2003 contours : galaxies at z=0

40. Spectral Diagnostics – tau model model grids: Bruzual & Charlot 2003 contours : galaxies at z=0

41. Spectral Diagnostics – burst model model grids: Bruzual & Charlot 2003 contours : galaxies at z=0

42. Outline 1 – Introduction 1-1 Environmental Dependence of Galaxy Properties 2 – Large-Scale Structures at z<1.2 2-1 Observational Data 2-2 Large-Scale Structures 3 – The Build-up of the Color-Magnitude Relation 3-1 Definitions of Environments 3-2 Color-Magnitude Diagrams 4 – Summary

43. Schematic View of Galaxy Evolution Environment Mass Time

44. Environment Mass Time Schematic View of Galaxy Evolution

45. Environment Mass Time Schematic View of Galaxy Evolution

46. Environment Mass Time Schematic View of Galaxy Evolution

47. Environment Mass Time Schematic View of Galaxy Evolution

48. Environment Mass Time Schematic View of Galaxy Evolution

49. Photometric Redshifts from VRiz photometry Redshifts of very blue galaxies deviate....

50. Fast Facts galaxy-galaxy mergers <1Gyr strong field/group harassment ? strong cluster ram-pressure stripping <1Gyr weak cluster strangulation ~1Gyr weak group/cluster mechanisms star formation morphology effective env.

51. redshift massive less massive red blue z=0 z=0.55 z=0.83 1 – We observed the build-up of the CMR. We suggest that galaxies follow the 'down-sizing' evolution, and the 'down-sizing' is delayed in low density environments. 2 – We spectroscopically confirmed the large-scale structures at z=0.83. Our current data seem to favour a scenario that star formation is quenced in a short time scale (<1Gyr). The physical process behind the build-up of the CMR would be galaxy-galaxy mergers.