1. The central few parsec region of AGN in the IR
M. Almudena Prieto (IAC)
Crete, June 2008

2. PARSEC program High spatial resolution study of the Nearest Active Galactic Nuclei in the Southern Hemisphere
From UV to optical (HST) to IR (adaptive optics ) to radio (VLA / ATCA)
What is new:
Achieved angular scales
VLT /AO µm  θ < 0.1” ( ~ pc)
VLT µm  θ < 0.4”
For some of the brightest:
Interferometry at 10 µm  θ ~ 0.03“ ( ~ 0.5 pc)
What we had:
HST at µm  θ < 0.1”
VLA/VLBA and ATCA  θ < 0.1”

3. Some of the nearest … 1”/pc L(20-100 keV) FWHMcore 2 µm
S2/RG CenA x < 1 pc
S Circinus x ~ 2 pc
S1/Li N x1040* < 10 pc
S N x ~1x2pc (10um)
S N * < 8 pc
S N x < 11 pc
S N x < 12 pc
S2 ESO x1042* < 20 pc
S N < 10 pc
S N3783 x < 22 pc
S N x < 38 pc
Qso 3C x < 300 pc

4. Some AGN dominate the galaxy light regardless of the aperture size
AGN in the IR
3C 273
NGC 5506
Sy 1.9
2MASS
Some AGN dominate the galaxy light regardless of the aperture size

5. AGN in the IR
NGC 1068
Centaurus A
NGC 1566
Circinus
2MASS
In others, the galaxy dominates IR light by at least an order of magnitude

6. Modest AGN: their IR luminosity is a few percent of the total IR output
RG / S2 S2 S1 S2

7. Dominating AGN: their IR luminosity is ~100% of the total
QSO S1 S2
3c273 from Lichti,… Courvoisier et al except radio which is taken from VLBI from different authors and IR

8. VLT / VISIR 10 - 20 um images down to 0.4 arcsec resolution 
excess IRAS flux has to come from diffuse extended emission
NGC Q
Galliano et al. 2006
Cen A : also found unresolved by Radomski et al 2008 (8.8 and 18.3um gemini South). In Gemini 18,3 um (filter is 1.5um width vs 0.37um in our case w. visir), a blob is seen next to the nucleus N-E In the jet direction, which is coinciding with a blob in Palpha emission (HST, Marconi)
Reunanen et al. 2008

9. …… but in other AGN:
excess IRAS flux comes from circumnuclear star forming regions
Liner / S1 S1 S2
NGC Q
Reunanen et al. 2008

10. The true energy output in the IR
LIRcore IR(large-ap/core) X>20kev / IRcore
S1/Li N x %
S2/RG CenA x
S Circinus x %
S N x
S N x1043  %
S N x %
S N x %
S N3783 4x %
Qso 3C x

11. Summary
AGN selection by IRAS colors has been very successful. This is surprising considering that:
IRAS luminosity overestimates the core luminosity by factors > 10
SEDs from large IR apertures differ dramatically from those derived at high spatial resolution
Large aperture IR excess found associated with starformation or low surface brightness emission
==> Acknowledging the IRAS success, it all looks as if galaxies would know a priori whether an AGN is being nursed at their core