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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.

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Galaxy Classification in the WISE Color-Luminosity Diagram

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  1. 우주탐사회워크샵@무주리조트2014. 2. 10. ~ 12. Galaxy Classification in the WISE Color-Luminosity Diagram 이광호 (서울대학교) SDSS DR10 WISE

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

  3. Galaxy Migration in CMD • In terms of - SF quenching - Mass buildup • A Key QuestionDid 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).

  4. To understand galaxy evolution,

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

  6. 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

  7. 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

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

  9. 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

  10. 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

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

  12. 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

  13. 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.

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

  15. 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.

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