jeju, 27-29 feb 2012, the legacy of akari: a panoramic view of the dusty universe
TRANSCRIPT
AKARI-SDSS-GALEX: Spectral energy distributions
of nearby galaxiesStar formation rates and dust attenuation
propertiesV. Buat1 , T. T. Takeuchi2 , F.-T. Yuan2,
E. Giovannoli1 , S. Heinis1
1 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 panoramic view of the dusty universe
Outline
• Samples definition • SED fitting on multi-λ data• Dust attenuation recipes• Green valley galaxies • SFR calibrations
Sample selections
AKARI FIS all sky survey FIS Bright Source Catalogue Xmatched with IRAS PSCz + SDSS/DR7 and GALEX/GR4-5 surveys
2MASS data also addedPrimary sample: 776 galaxies selected at 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
SED fitting with CIGALE
Reliability of SED fitting results checked on artificial galaxies:
Buat et al. 2011
Parameter estimationStar formation history
Dust attenuation
Dust emission
Dust attenuation
Takeuchi et al. 2010, Buat et al. 2011
Meurer et al. 95, 99, Calzetti et al. 00
f(1200-2500Å), : a proxy for dust attenuation in local starburst galaxies observed by IUE and IRAS
The slope of the UV continuum: a measure dust attenuation?
Dale et al. 07See also Boissier et al. 07Munoz-Mateos et al. 09
SINGS
see also Howell 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…
Buat et al. 2011AKARI-SDSS-GALEX data + SED fitting Very dispersed relations
A FUV
(fro
m L
ir/L U
V) m
ag
o LIRGs__ Meurer et al 99 Seibert et al. 05- - Salim et al 07
Takeuchi et al. 10
FUV-NUV a proxy for ß
AKARI-SDSS-GALEX: a very large dispersion
FUV-NUV
FUV-r
colour
AFUV = 2.39 (FUV-NUV)+0.89 (σ = 0.83) σ(FUV-NUV) = 0.2 mag σ(AFUV) = 0.5 magAFUV = 0.65 (FUV-r)+0.04 (σ = 0.76) σ(FUV-r) = 0.2 mag σ(AFUV) = 0.1 mag
UV-optical colours are only crude estimators of dust attenuation
See also Johnson et al. 2007
Green valley: star formation and dust attenuationTakeuchi et al. 2010, Heinis et al. in prep
Blue cloud star forming galaxies NUV-r < 3.5Red cloud, quiescent galaxiesNUV-r > 4.7Green valley3.5<NUV-r<4.7
Galaxies in the green valley:
Distributions of D4000 and SSFR close to those of the blue cloud galaxies but with a tail towards quiescent galaxies.The galaxies in the green valley have larger attenuations than blue galaxies
On going work
SFR calibrations
Buat et al. 2011: Combining IR and UV dataYuan et al. 2011: Calibration of MIR fluxes
Adding UV and IR measurements to estimate the SFRsBuat et al. 11
SFR(Msun yr-1) = (1-) SFR(IR)+SFR(UVobs)
SFR(IR) and SFR(UV) from recipes (e.g. Kennicutt 98)
corresponds to the fraction of L(IR) due to the heating by old starsHirashita et al. 03, Iglesias-Paramo et al. 04,06, Bell 03 = 0.3-0.4 (star forming galaxies)
η= 0.17 +/- 0.10
logSFR9 = 0.99 log(L9)-9.02 (σ=0.18 dex) logSFR18 = 0.90 log(L18)-8.03 (σ=0.20 dex)
MIR luminosities calibrated in SFRsYuan et al. 2011
Comparison with calibrations from Spitzer
AKARI
Log(SFR8/SFR9) = -0.14 +/- 0.18 (Wu et al)Log(SFR8/SFR9) = -0.25 +/- 0.16 (Zhu et al)
Fluxes at 8 and 24 µm from the best model (Dale and Helou 02 templates)
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)
Conclusions• Reference samples based on a FIR selection and with
large wavelength coverage.• Reliable SFR and dust attenuation retrieved from SED
fitting, calibrations investigated. • Green valley galaxies easily identified: combination of
dusty « blue cloud » galaxies and more quiescent objects
• Samples which can be used for comparison in high z studies:
Elbaz et al., Wang et al. (similar samples) Symeonidis et al (in prep)