1. An Infrared View of Clusters of Galaxies: CLEVL Myung Gyoon Lee ( 李明均 ) Gwang-Ho Lee ( 李光鎬 ) Seoul National University Seoul, Korea AKARI/CLEVL team With AKARI/CLEVL team (H.M. Lee, M. Im, H.S. Hwang, S.J. Kim, N. Hwang, J.C. Lee, S. Lim, H. Shim, J. Ko, H. Seo, H. Matsuhara, T. Kodama, T. Takagi, T. Nakagawa, T. Wada, Y. Koyama, T. Goto, et al.)

2. Outline Overview of clusters of galaxies AKARI CLEVL An AKARI Mission program: The CLusters of galaxies EVoLution (CLEVL) Future – WISE study

3. A New Era for Clusters Optical: clustering of galaxies (~1950s, Zwicky and Abell) X-ray: Discovery of Hot ICM Infrared: Unobscured view of the SFA (NIR/MIR/FIR) Ground-based: 2MASS → GMT, TMT, eELT etc. AKARI Space: ISO, AKARI, SST, Herschel, WISE → JWST, SPICA, etc. WISE A3395 (z=0.051) WISE A3395 (z=0.051) AKARI A2219 (z=0.226) AKARI A2219 (z=0.226)

4. CLEVL CLusters of galaxies EVoLution studies AKARI Mission Program (PI: Hyung Mol Lee) Instruments: AKARI / IRC (N3, N4, S7, S11, L15, L24) Three Groups Low-z (z<0.4): Myung Gyoon Lee et al. Mid-z (0.4<z<1.1): T. Kodama et al. High-z (z>1.1): T. Takagi et al.

5. CLEVL: Low-z Clusters 9 nearby clusters at varying phase of merging ClusterszN(p)BM typeRemarks A20650.0732III Compact merger (starting), unequal mass merger A21990.0302I Core region in the A2199 supercluster A22180.1768I-II Deep survey using lensing (by Serjeant) A22190.2268III Merging, elongated, LIRGs (ISO) A22550.0818II-III Merger after core-crossing A31280.0606I-II Binary cluster with A3125 A33890.0276II-III Complex multiple structures A33950.0514II Binary cluster with A3391 A35580.0482I Core region in the Shapley supercluster

6. Goals: Low-z Clusters Effect of cluster merging on SF activity & cluster evolution to tell triggering or suppressing SF? to find hidden SF, if any? Evolution of galaxies falling into clusters to witness quenching of SF? Origin of S0 problem spatial distribution of galaxies with MIR emission and early-type morphology → transformer?

7. Selection of cluster membership Using spec-z from SDSS, WINGS, NED

8. Selection of cluster membership Blue circles: member galaxies selected by cz (± 1500 km s -1 ) Blue circles: member galaxies selected by cz (± 1500 km s -1 )

9. N3 – Mass / S11 – SFR relations N3 ← NIR emission coming from old stellar pop. ◎ N3 is useful to estimate stellar mass of galaxies. S11 ← MIR emission coming from star-forming region. ◎ S11 is used as a rough measure of SFR. slope = -0.46 intc = 1.19 σ = 0.16 slope = -0.46 intc = 1.19 σ = 0.16 slope = -0.44 intc = -9.24 σ = 0.42 slope = -0.44 intc = -9.24 σ = 0.42

10. (N3-S11) vs. SSFR Slope = 0.71±0.05 intc = -10.71±0.06 (N3-S11) color is a good indicator of specific SFR for galaxies with (N3-S11)>-2.0.

11. (N3-S11) vs. Age A2255 (Shim et al. 2011) Weak MIR-excess Passively evolving age > 10 Gyr Weak MIR-excess Passively evolving age > 10 Gyr Intermediate MIR-excess ages 1~10 Gyr small amount of SF Intermediate MIR-excess ages 1~10 Gyr small amount of SF Strong MIR-excess Star-forming Strong MIR-excess Star-forming

12. Color-Magnitude Diagram + Crosses (N3-S11) < -2.0 + Crosses (N3-S11) < -2.0 ◎ Circles -2.0≤(N3-S11) < -1.2 Weak Weak MIR-excess ◎ Circles -2.0≤(N3-S11) < -1.2 Weak Weak MIR-excess ◈ Diamonds -1.2≤(N3-S11) < 0.2 Intermediate Intermediate MIR- excess ◈ Diamonds -1.2≤(N3-S11) < 0.2 Intermediate Intermediate MIR- excess ★ Stars (N3-S11) ≥0.2 Strong Strong MIR-excess ★ Stars (N3-S11) ≥0.2 Strong Strong MIR-excess

13. (N3-S11) Color Distribution Some clusters (A2219, A2255, A3128) have fraction of high- SFR galaxies larger than 15%. core-crossing merging binary Age (Gyr) 1>10

14. Radial variation MIR-red galaxies are preferentially located in the outskirt.

15. Spatial distribution of galaxies Abell 2218 (z = 0.176) Abell 2219 (z = 0.226) Abell 3128 (z = 0.060) and others

16. Spatial distribution of galaxies The central region of A2218 is dominated by weak (or intermediate) MIR-excess galaxies. Ko et al. 2009 ● WMIR ◆ IMIR ★ SMIR □ MIR-excess

17. Spatial distribution of galaxies X-ray: A2219 is elongated in the SE-NW direction. At R<0.5 R 200,cl, we found several MIR-red galaxies. Boschin et al. 2004 ● WMIR ◆ IMIR ★ SMIR

18. Spatial distribution of galaxies Rich, highly substructured cluster: two cores separated by 12 arcmin. The fraction of strong MIR-excess galaxies with (N3-S11)>0.2 is >20%. A3128 encountered a tidal interaction with A3125 (~ 6Mpc). Werner et al. 2007 1 Mpc A3125 direction ● WMIR ◆ IMIR ★ SMIR

19. Spatial distribution of galaxies Compact merger (starting) Compact merger (starting) Complex multiple structures Complex multiple structures Binary cluster with A3391 Binary cluster with A3391 Core region in SS Core region in SS

20. SSFR for clusters S11 absolute magnitude → SFR SSFR = ∑ SFR (for SFR > 2.0 M ⊙ yr -1 within 0.5 R 200,cl ) / M cluster △ Bai et al. 2007 ★ This Study △ Bai et al. 2007 ★ This Study Abell 2255 Abell 2218 Abell 2219

21. Future – WISE study Wide-field Infrared Survey Explorer All-sky (preliminary DR covers 57% of whole sky) Wavelength: 3.4 (W1), 4.6 (W2), 12 (W3) and 22μm (W4) March 2012

22. Abell 2199 Supercluster The most mass systems in nearby universe: z = 0.03 A2199 is kinematically connected to A2197E/W and infalling galaxy groups. An excellent laboratory for studying galaxy evolution, thanks to a high-density environment and complex structures. Lee et al. in prep.

23. Summary & Conclusion AKARI (N3-S11) color is a very efficient tool to find MIR excess galaxies in clusters. The fraction of star forming galaxies varies among clusters. Star forming galaxies in clusters are located preferentially in the outskirts. AKARI opened a new era for galaxy clusters, and WISE also will do!