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