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Takeuchi et al. A&A, 2010, 514, A4 Buat et al. A&A, 2011, 529, A22

AKARI - SDSS - GALEX : Spectral energy distributions of nearby galaxies Star formation rates and dust attenuation properties V. Buat 1 , T. T. Takeuchi 2 , F.-T. Yuan 2 , E. Giovannoli 1 , S. Heinis 1 1 Laboratoire d’Astrophysique de Marseille 2 Nagoya University.

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Takeuchi et al. A&A, 2010, 514, A4 Buat et al. A&A, 2011, 529, A22

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  1. AKARI-SDSS-GALEX:Spectral energy distributions of nearby galaxiesStar formation rates and dustattenuationpropertiesV. Buat1 , T. T. Takeuchi2 , F.-T. Yuan2, E. Giovannoli1 , S. Heinis11 Laboratoire d’Astrophysique de Marseille2 Nagoya University • Takeuchi et al. A&A, 2010, 514, A4 • Buat et al. A&A, 2011, 529, A22 • Yuan et al. PASJ, 2011, 63, 1207 Jeju, 27-29 Feb 2012, The legacy of Akari: a panoramicview of the dustyuniverse

  2. Outline • Samplesdefinition • SED fitting on multi-λ data • Dustattenuationrecipes • Green valley galaxies • SFR calibrations

  3. Sampleselections AKARI FIS all skysurvey FIS Bright Source Catalogue Xmatchedwith IRAS PSCz + SDSS/DR7 and GALEX/GR4-5 surveys 2MASS data alsoadded Primarysample: 776 galaxies selectedat 90 µm: (Takeuchi et al. 2010) 363 galaxies all detected 153 galaxies Xmatched at 140 µm with AKARI/IRC PSC (Buat et al. 2011) (Yuan et al. 2011) and poster 2-21 for details

  4. SED fittingwith CIGALE Reliability of SED fittingresultschecked on artificial galaxies: Buat et al. 2011

  5. Parameter estimation Star formation history Dustemission Dustattenuation

  6. Dustattenuation Takeuchi et al. 2010, Buat et al. 2011

  7. Dale et al. 07 SeealsoBoissier et al. 07 Munoz-Mateos et al. 09 The slope of the UV continuum: a measuredustattenuation? f(1200-2500Å), : a proxy for dustattenuation in local starburst galaxies observed by IUE and IRAS Meurer et al. 95, 99, Calzetti et al. 00 SINGS

  8. AKARI-SDSS-GALEX: a very large dispersion AFUV (fromLir/LUV)mag o LIRGs __ Meurer et al 99 Seibert et al. 05 - - Salim et al 07 Takeuchi et al. 10 Buat et al. 2011 AKARI-SDSS-GALEX data + SED fitting Verydispersed relations FUV-NUV a proxy for ß seealsoHowell et al 2010, Goldader et al. 2002, Buat et al. 2005, Seibert et al. 05 Munoz-Mateos et al. 09, Overzier et al. 10 etc…

  9. UV-opticalcolours are onlycrudeestimators of dustattenuation FUV-NUV FUV-r AFUV = 2.39 (FUV-NUV)+0.89 (σ = 0.83) σ(FUV-NUV) = 0.2 mag σ(AFUV) = 0.5 mag AFUV = 0.65 (FUV-r)+0.04 (σ = 0.76) σ(FUV-r) = 0.2 mag σ(AFUV) = 0.1 mag colour Seealso Johnson et al. 2007

  10. Green valley: star formation and dustattenuationTakeuchi et al. 2010, Heinis et al. in prep Blue cloud star forming galaxies NUV-r < 3.5 Redcloud, quiescent galaxies NUV-r > 4.7 Green valley 3.5<NUV-r<4.7

  11. Galaxies in the green valley: Distributions of D4000 and SSFR close to those of the bluecloud galaxies but with a tailtowards quiescent galaxies. The galaxies in the green valley have largerattenuationsthanblue galaxies On goingwork

  12. SFR calibrations Buat et al. 2011: CombiningIR and UV data Yuan et al. 2011: Calibration of MIR fluxes

  13. AddingUV and IR measurements to estimate the SFRs Buat et al. 11 • SFR(Msun yr-1) = (1-) SFR(IR)+SFR(UVobs) • SFR(IR) and SFR(UV) fromrecipes (e.g. Kennicutt 98) •  corresponds to the fraction of L(IR) due to the heating by old stars • Hirashitaet al. 03, Iglesias-Paramo et al. 04,06, Bell 03  = 0.3-0.4 (star forming galaxies) η= 0.17 +/- 0.10

  14. MIR luminositiescalibrated in SFRs Yuan et al. 2011 logSFR18 = 0.90 log(L18)-8.03 (σ=0.20 dex) logSFR9 = 0.99 log(L9)-9.02 (σ=0.18 dex)

  15. Comparisonwith calibrations fromSpitzer Fluxes at 8 and 24 µm from the best model (Dale and Helou 02 templates) AKARI Log(SFR8/SFR9) = -0.14 +/- 0.18 (Wu et al) Log(SFR8/SFR9) = -0.25 +/- 0.16 (Zhu et al) Log(SFR24/SFR18) = -0.01 +/- 0.12 (Wu et al) Log(SFR24/SFR18) = -0.05 +/- 0.11 (Zhu et al) Log(SFR24/SFR18) = -0.04 +/- 0.17 (Rieke et al)

  16. Conclusions • Referencesamplesbased on a FIR selection and with large wavelengthcoverage. • Reliable SFR and dustattenuationretrievedfrom SED fitting, calibrations investigated. • Green valley galaxies easilyidentified: combination of dusty « bluecloud »  galaxies and more quiescent objects • Sampleswhichcanbeused for comparison in high z studies: Elbaz et al., Wang et al. (similarsamples) Symeonidis et al (in prep)

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