Interferometric 3D observations of LIRGs Masa Imanishi NAOJ (National Astronomical Observatory of Japan) NMA (Nobeyama Millimeter Array)

Luminous infrared galaxies（LIRGs） L(IR) > 10^11 Lsun (Normal spiral ~ 10^10 Lsun) optical IR M100（Sbc） LIRGs IR optical Luminous energy source is hidden behind dust

AGNs in LIRGs are buried NLR AGNs obscured by torus-shaped dust Sy2 Detectable via optical spectroscopy LIRGs have a large amount of nuclear gas and dust Buried AGNs are elusive >80% LIRGs = non-Sy

buried AGN or compact SB ? X-ray : AGN >> SB Compton thick (NH>10^24 cm-^2) buried AGN in LIRGs Future X-ray satellite sensitive at E > 10keV

Effects to the surrounding ISM Maloney et al.1996 XDR around an X-ray emitting buried AGN

0.5% * Mc2 SB << 1 pc 6-40% * Mc2 Hot dust (several 100K) Strong mid-IR (10-20um) emission AGN

Millimeter line ratio AGN and SB separated HCN/HCO+ J=1-0 HCN/CO Starburst pure AGN J=1-0 (Kohno astro-ph/0508420)

Resolve multiple-nuclei Our NMA interferometric HCN/HCO+ survey Compared to single-dish obs.: Extract only nuclear emission Resolve multiple-nuclei HCN/HCO+ taken simultaneously

NMA data Single nucleus LIRGs HCN > HCO+ HCN > HCO+ NGC4418 (Buried AGN) UGC5101 （Buried AGN） Mrk273 （Buried AGN） HCN > HCO+ HCN > HCO+ HCN > HCO+ Imanishi et al. 2004 AJ 128 2037 Imanishi et al. 2007 AJ 131 2888

NMA data (II) HCN > HCO+ HCN > HCO+ NMA Mrk 231 IR08572+3915 (Buried AGN) Mrk 231 （type-1 AGN） HCN > HCO+ HCN > HCO+ Imanishi et al. 2007 AJ 134 2366

Spatially resolve multiple components (1) HCN < HCO+ Arp299 Imanishi & Nakanishi 2006 PASJ 58 813 HCN ~ HCO+

Spatially resolve multiple components (2) HCN > HCO+ HCN < HCO+ Mrk 266 Imanishi et al. 2008 in prep

Spectrally resolve multiple components W-nucleus E-nucleus Imanishi et al. 2007 AJ 134 2366 Spatially-unresolved

NMA HCN/HCO+ IR-buried -AGNs ★:LIRGs IR-Starburst HCN/CO

Interpretation High HCN/HCO+ in AGN HCN abundance enhancement Meijerink et al. 2006 2. IR-radiative pumping enhance HCN flux

Molecular gas high abundance ρ∝r^-1.5 low abundance abundance tau=1 sphere ρ∝r^-1.5 (Gierence et al. 1992) abundance surface area flux

HCN/HCO+ abundance: model dependent PDR XDR HCO+/HCN NH high low density=10^5.5 cm^-3 Meijerink et al. 2006

Interpretation High HCN/HCO+ in AGN HCN abundance enhancement 2. IR-radiative pumping enhance HCN flux HCN has a line at 14um Aalto et al. 1995

IR radiative pumping HCN has a line at 14um 14um AGN is a strong Aalto et al. 1995 HCN has a line at 14um HCN(1-0) Cascade AGN is a strong IR 14um emitter (hot dust) 3.5mm 14um

HCO+ line at 12um is weak ! Not detected !

high HCN(1-0)/HCO+(1-0) ratios in nuclei of buried AGN candidates Summary NMA 3D (spatial and velocity) data : high HCN(1-0)/HCO+(1-0) ratios in nuclei of buried AGN candidates Imanishi et al. 2006 AJ 131 2888 Imanishi et al. 2007 AJ 134 2366 Imanishi et al. 2008 in prep

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High-CR PDR XDR HCN(1-0)/HCO+(1-0) intensity ratio = high (in some parameter range) High-CR PDR XDR 10^4/cc G0= 10^3 10^4 10^5 FX=1.6 16 160 HCN(1-0)/ HCO+(1-0) 0.36 0.34 0.32 21.7 22.6 Meijerink et al. 2006

ULIRGs Compact cores (<500pc) are energetically dominant optical IR(12um) Soifer et al. 2000 Very compact starburst or AGN ?

Outline 1. IR spectroscopy 2. Mm interferometric HCN(1-0) and Select buried AGN candidate 2. Mm interferometric HCN(1-0) and HCO+(1-0) follow-up observation HCN(1-0)/HCO+(1-0) ratio

3-4 um Subaru Buried AGN SB AGN+SB PAH strong (SB): Dust abs. weak Ice 3.1um Bare 3.4um PAH 3.3um PAH strong (SB): Dust abs. weak PAH weak (AGN): Dust abs. strong

5-35 um Spitzer GO1 SB Buried AGN AGN+SB PAH PAH PAH PAH PAH strong : Silicate Abs. weak PAH weak: Silicate Abs. strong

Remaining ambiguity ★ SB AGN Exceptionally centrally-concentrated SB Very high surface brightness >>10^13Lsun/kpc^2 (SB max) Extreme SB? AGN

Interpretation High HCN/HCO+ in AGN HCN abundance enhancement 2. IR-radiative pumping enhance HCN flux 3. Turbulence decreases HCO+ Papadopoulos 2007 Regardless of AGN or SB ? 4. High gas density

Interpretation High HCN/HCO+ in AGN HCN abundance enhancement 2. IR-radiative pumping enhance HCN flux 3. Turbulence decreases HCO+ 4. High gas density N(crit): HCN ~ 5 * HCO+

★:(U)LIRGs High gas density ULIRG : low HCN/CO scenario: unlikely ? PDR XDR HCN/CO HCN/HCO+ ★:(U)LIRGs

NMA/RAINBOW data （III） Buried AGN AGN SB or AGN ? Imanishi et al. 2007 ArXiv/0709.1713

1. Infrared spectral shape PAH PAHs are excited in starburst PDRs but destroyed near an AGN Buried AGN EW(PAH)<<100nm composite Starburst(SB) 3.3um PAH featureless EW(PAH)~100nm 3.4um/3.1um

2. Dust absorption feature strength starburst Buried AGN ULIRG core <500pc Foreground screen dust　model strong exp(-Tau) (Imanishi & Maloney 2003 ApJ 588 165) Mixed dust model Dust absorption feature: weak Tau(3.1) < 0.3 Tau(3.4) < 0.2 1-exp(-Tau) Tau Tau(9.7) < 1.7

3. Dust temperature gradient Av(3um) > Av(10um) > Av(20um) Buried AGN Av(3um) =< Av(10um) 　　　=< Av(20um) Starburst dust in edge-on host

How to detect T-gradient ? Spitzer Subaru Av(20um) ~20mag Av(3um) ~110mag Av(10um) ~40mag Optical depth 9.7um 18um Dust temperature gradient

Strong T-gradient (II) Spitzer Subaru Strong abs ULIRGs -> often show T-gradient

Opical non-Seyfert ULIRGs Results nearby(z<0.15) Opical non-Seyfert ULIRGs Luminous buried AGNs = 30-50% 30% ULIRGs = optical Sy (AGN + torus) >50% ULIRGs = luminous AGN NLR

L(dereddened AGN) ～L(IR) Our line-of-sight obscuration: Non-Sy >> Sy2 NLR Sy2: Abs weak Non-Sy: strong L(dereddened AGN) ～L(IR) Amount of nuclear dust: Non-Sy >> Sy2

Interpretation High HCN/HCO+ in AGN HCN abundance enhancement 2. IR-radiative pumping enhance HCN flux 3. Turbulence decreases HCO+ 4. High gas density 5. CR-controlled chemistry Papadopoulos 2007 HCN/HCO+ < 1

★:(U)LIRGs XDR IR-buried -AGNs IR-Starburst PDR NMA (RAINBOW) HCN/HCO+ ★:(U)LIRGs XDR IR-buried -AGNs IR-Starburst PDR HCN/CO Imanishi et al. 2006 AJ 131 2888; 2007 in prep

Summary Imanishi et al. 2006 ApJ 637 114 1. Buried AGNs : 30-50% non-Sy ULIRGs warm & cool 2. Nuclear dust amount: non-Sy ULIRGs > Sy2 ULIRGs Optical Sy (non-)detectability depends on the amount of nuclear dust Imanishi et al. 2006 ApJ 637 114 Imanishi et al. 2007 ApJS astro-ph/0702136

cool == starburst Buried AGNs: both warm/cool FIR colors NLR warm pure buried AGN NLR warm larger dust column cool FIR color F25/F60=0.16(cool) cool == starburst