Galaxy Classification in the WISE Color-Luminosity Diagram 우주탐사회 워크샵 @무주리조트 2014. 2. 10. ~ 12. Galaxy Classification in the WISE Color-Luminosity Diagram 이광호 (서울대학교) SDSS DR10 WISE

Optical Color-Magnitude Diagram Red quiescent galaxies, mainly ETGs Green Valley Blue star-forming galaxies, mainly LTGs Masters+11

Galaxy Migration in CMD In terms of - SF quenching - Mass buildup A Key Question Did quenching occur early in the process of mass buildup, midway, or late? Faber+07 The transition timescale must be short (~ 1 Gyr)!! Since the color bimodality will never be seen if the transition timescale is over a Hubble time (Pan+10).

To understand galaxy evolution,

Galaxy classification based on MIR colors Star-forming galaxies AKARI (N3-S11) color Transition Objects Quiescent galaxies Shim+2011

Spectral Energy Distribution (Model) SED of Starburst galaxies Observed SED da Cunha+08 Unattenuated stellar spectrum Emission by dust in the ambient ISM Emission by dust in stellar birth cloud

Multi-wavelength data SDSS DR10 + WISE combined galaxy catalog Wide-field Infrared Survey Explorer (WISE) All sky survey four MIR bands (3.4, 4.6, 12, 22μm) 79,579 galaxies at 0.01< z <0.06 - S/N12μm > 5 - Excluding AGNs GALEX NUV data WISE 설명 하나로.

MIR CLD CLD WISE [3.4] – [12] ≈ AKARI N3 – S11 ∝𝑺𝑭𝑹/ 𝑴 𝒔𝒕𝒂𝒓 MIR star-forming sequence (Hwang +13) : SFR ~ Mass relation MIR emission from AGB dust (Piovan+03) : SSP with different ages (1~10 Gyr)

Early-type galaxies The second population spans [3.4] – [12] corresponding the colors of ETGs with MIR-excess cover. Piovan+03 Mean age young old

Late-type galaxies ∆MIRC: deviation of [3.4] – [12] from the SFSG (red line) A left long tail: ∆MIRC < -1 mainly LTGs w/o SF nuclei

MIR Galaxy Classification MIR star-forming sequence MIR green valley MIR blue clump

vs. Optical CMD MIR green valley ≠ Optical green valley Transition timescale from MIR GV to MIR BC: ~ # Gyrs MIR GV → MIR BC: optically red galaxies w/ RSF → DEAD galaxies

NUV – r vs. [3.4] – [12] Two-component SSP model : small amount of young (0.5, 1, 2 Gyr) populations make galaxies have MIR-excess emission (MIR GV). NUV-excess galaxies (NUV – r > 5.4) → MIR-excess galaxies → Quiescent galaxies (Ko+13) NUV is sensitive to very recent (<1 Gyr) SF, MIR is sensitive to SF over longer timescale. NUV – r colors of MIR GV and MIV BC are overlapped.

ATLAS3D Cappellari+13 Multi color imaging + 2D kinematics for 260 ETGs (d < 42 Mpc) Slow / Fast Rotators Emsellem+13

Conclusion We present a new galaxy classification scheme in the WISE [3.4] – [12] color vs. 12μm luminosity diagram. We classify galaxies into three types: MIR star-forming galaxies, MIR green valley galaxies, MIR blue clump galaxies. To obtain a better understanding of galaxy evolution, we need to focus on RGB of galaxies. WISE 설명 하나로.