Subaru AO high-spatial-resolution IR K- and L-band search for buried dual AGNs in merging galaxies
description
Transcript of Subaru AO high-spatial-resolution IR K- and L-band search for buried dual AGNs in merging galaxies
Subaru AO high-spatial-resolution IR K- and L-band search for buried dual
AGNs in merging galaxies
Masatoshi Imanishi ( 今西昌俊 )
NAOJ/Subaru Telescope
Imanishi+14 ApJ 780 106
Gas-rich galaxy mergers common in the universe
Simulation(Kazantzidis)
HST image
CDM galaxy formation:
Multiple SMBHs common in mergers
SM
BH
mass
bulge massNASA
bulge massS
MB
H m
ass
Gultekin+09
Supermassive blackhole ( SMBH ) ubiquitous at galaxy center
Many dual AGNs expected, if SMBHs are active
Wang+09 ApJ 705 L76
Double-peaked optical emission lines
~1% (87 / 6780 z<0.15 type-2 AGN)
Hβ
[OIII]4959
[OIII]5007
Dual AGN
outflow
jet interaction
Two discrete line emitting clouds
See also Liu+10,11, Smith+10, Pilyugin+12, Ge+12,Barrows+13
Fu+11b ApJ 733 103
Follow-up of double-peaked lines objects
~30% ( 16/50 ) double nuclei
Dual AGNs not required in the majority (~70%)( Jet-cloud interaction etc )
10”
Keck II/OSIRIS+LGS-AOH-band
Very small (<1%) dual AGN fraction in double-peaked lines dual AGN search
• miss face-on SMBHs
Edge-on:OK Face-on:undetectable
• Buried AGNs undetectable
Need observations at wavelengths oflow dust extinction
High-spatial-resolution imaging
Sensitive to face-on multiple SMBH with small separation
• radio (VLBI)
• X-ray 2-10 keV (Chandra; 0.5”)
Miss the majority of radio-quiet AGN
Miss Compton-thick (NH > 1024 cm-2) AGNs
Burke-Spolaor11
Teng+05,09,12,Iwasawa+11a,11b, Koss+12,Liu+13
Our method: Subaru AO infrared imaging
• Infrared K (2.2um) and L’(3.8um)
• Subaru-AO (0.1-0.15”)
Sensitive to buried AGNs, including radio-quiet ones
Sensitive to small separation (face-on) dual AGNs at late merging stage
AKARI 2.5-5um spectroscopy
Normal starbust
Buried AGN
PAH
Imanishi+10 ApJ 721 1233
Starburst: K-L blue(~0.5 mag)
Buried AGN: K-L red (~2 mag)
(AGN heated hot dust emission)
AGN (red K-L nucleus)
28/29 (U)LIRGs show at least one AGN
10”Imanishi+14 ApJ 780 106
Dual AGNs (two red K-L nuclei)
10”Imanishi+14 ApJ 780 106
4/29 (U)LIRGs
Subaru AO L’(3.8um) (0.1-0.2”)
Spitzer IRAC3.6um (1”/pix)
WISE3.4um >5”
Small fraction (15%) of IR buried dual AGN
1. Dust obscuration ?
2. Orbiting geometry ?
3. Non-simultaneous SMBH activation
SMBH mass ratio between two nuclei
AG
N lu
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Less massive SMBHhas high Eddington ratio
More massive SMBH is more actively mass accreting (=high Eddington ratio)
Imanishi+14 ApJ 780 106
More massive SMBH has higher Eddington ratio
Non-simultaneous SMBH activation throughout the merging phase
Imanishi+14ApJ 780 106
Our Infrared K- and L-band AO imaging revealed non-simultaneous SMBH activation
Even if two SMBHs are present, only one SMBH can become sufficiently luminous to be detectable as an AGN
Can explain the observed small dual AGN fraction in merging galaxies
Summary
More massive SMBHs have higher Eddington ratio
Summary 2
SMBH activation is dominated by local conditions, rather than global galaxy properties
Difficult to predict by simulation
Need observational constraints
Imanishi+14 ApJ 780 106
End
Buried AGN
Lν(3-4μm) (intrinsic) = L(AGN)ν