A MULTI-WAVELENGTH STUDY OF DISTANT IR GALAXIES
Toshinobu Takagi (ISAS/JAXA)
H.Matsuhara, T.Wada, (ISAS/JAXA),Y.Ohyama (ASIAA), S. Oyabu (Nagoya Univ.), H.Hanami, T.Ishigaki (Iwate Univ)
and the AKARI extragalactic team
Why Infrared Galaxies?dominating star formation activity at z>1
Transition phase of massive galaxies? (Merger→AGN→elliptical)
In maximum phase of feedback in galaxies(M-σ relation)
28 Jul 2005 16:0 AR AR251-AA43-18.tex XMLPublishSM(2004/02/24) P1: KUV
786 VEILLEUX ! CECIL ! BLAND-HAWTHORN
Figure 4 M82, imaged by the Wisconsin Indiana Yale NOAO telescope in H! (magenta)and HST in BVI continuum colors (courtesy Smith, Gallagher & Westmoquette). Several ofthe largest scale filaments trace all the way back to super-starclusters embedded in the disk.
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(c)NASA
Goto, TT et al. (2010)
Sanders & Mirabel (1996)
Why are PAHs important?For the extragalactic science, PAH emission is only used as a SFR indicator.
This is because of the sensitivity issue. PAHs are the only dust emission in many cases at high-z.
Needs more study...Metallicity (PAH depression in low Z)
Radiation field (Variation of inter-band ratio)
Nordon+2011
galaxies at z~2
PAHs have information of ISM, more than just SFRs!
�����• Multi-wavelength Surveys
5
The NEP Survey★ Deep : 0.5 deg2 (224 pointing)★ Wide : 5.8 deg2 (450 pointing)
NEP-Wide
NEP-Deep
1 deg
NIR: 2, 3, 4 μmMIR-S: 7, 9, 11μm MIR-L: 15, 18, 24μm
★ In all IRC bands
全指向観測の約14%
MIR source (7284 obj) catalogue in NEP-Deep (TT+2012)
Polletta et al. (2007)
Example of Spitzer SEDs AKARI SEDs
AKARI gives more accurate SED classification.
AKARI/IRC
N2, N3, N4 S7, S9W, S11 L15, L18W, L24
Subaru/BRz’ N2 N3 N4 S7 S9W S11 L15 L18W L24
AKARI MIR color images
AKARI/IRC
N2, N3, N4 S7, S9W, S11 L15, L18W, L24
Subaru/BRz’ N2 N3 N4 S7 S9W S11 L15 L18W L24
AKARI MIR color images
PAH-selected galaxies
Selection method★ Selection: flux ratio (in Jy) F(11)/F(7)>8
Takagi et al. (2010)F(11)/F
(7) Specific SFR
★ 56 PAH-selected galaxies in 0.5 deg2
Starburst SED modelBased on chemical evolution model
MW, LMC, SMC dust models adopted
Temperature fluctuation of small dust including PAH
Radiative transfer in spherical symmetry
Takagi et al. (2003)
SED fitting examplePAH-selected galaxies at z~0.5
Good fit for 60% of PAH-selected galaxies
Systematic failure in 5-8μm (C-C mode)
Good fit in 10-16μm (C-H mode)
F(obs.)/F(m
odel)
Good fits
Bad fits
Li & Draine
Absorption cross-section of PAH
PAH variation?Spoon+2007
Local SEDs cannot reproduce rest 11/8 colour of PAH galaxies
Redshift0.4
15/11μ
m flux ra
tio
(Rest frame 11/8μm at z=0
.4)
0.5
Arimatsu et al.
M82
S7/S11 ratio
AGN?
(c)NASA
Optically-confirmed AGNs
~10% of AKARI MIR galaxies
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AGNs have a large excess of fluxes at rest-frame 2~6μm, compared to starburst SED models.
AGNs can be identified with multi-λ MIR photometry.
AGN
Starburst
SED fitting with zspec
Hydro+RT simulation
Snyder et al. (2012)
GADGET-2 Sunrise Hydrodynamical simulation with GADGET-2 with AGN
Radiative Transfer for selected lines of site
Propose photometric method to derive AGN fraction
Hydro+RT simulation
Snyder et al. (2012)
GADGET-2 Sunrise Hydrodynamical simulation with GADGET-2 with AGN
Radiative Transfer for selected lines of site
Propose photometric method to derive AGN fraction
Hatziminaoglou et al. (2010)
AGN-Starburst compositesBoth SF and AGN are active. Maximum feedback phase.
So far, SFR of AGN system is not well constrained.
ALMA’s resolving power to extract central sourceδr = 50-100 pc @ z>0.5 for θ=0.01”
Farrah et al. (2003)
SummaryWe conducted multi-λ IR surveys with AKARI.
At z~0.5, we identify galaxies with strong PAH emission in the photometric (NEP-Deep) survey with AKARI.
Starburst SED model (SBURT) reasonably reproduces the observed SEDs, but with systematic deviation around 8μm. More ionized PAHs?
In PAH-selected galaxies, intensive starbursts, like the central part of M82, could spread across the whole body.
AGNs can be identified with MIR, but we need high-resolution FIR-submm observations to derive SFRs in AGNs.
SummaryWe conducted multi-λ IR surveys with AKARI.
At z~0.5, we identify galaxies with strong PAH emission in the photometric (NEP-Deep) survey with AKARI.
Starburst SED model (SBURT) reasonably reproduces the observed SEDs, but with systematic deviation around 8μm. More ionized PAHs?
In PAH-selected galaxies, intensive starbursts, like the central part of M82, could spread across the whole body.
AGNs can be identified with MIR, but we need high-resolution FIR-submm observations to derive SFRs in AGNs.
AKARI-Deep Field SouthA prestigious FIR survey field: AKARI, Spitzer, Herschel, AzTEC
AzTEC
Herschel/PACSサーベイADF-S
Hatsukade et al. in prep