1. Tracing the coronal emission in AGN with VLT/NACO
NACO is here !
Olivier Marco

2. What is an AGN ?

3. AGN: a closer view
Scale: << 1 pc

4. From seeing limited to AO images
An example: NGC1068
DSS infrared
60”x60”
2mass
10”x10”
COME-ON+
1”x1”
NACO
1”x1”
deconvolved

5. So we can we NACO for AGN…
Yes !
But… very red objects & extended
Visible-WFS (all IR flux to CONICA) or
IR-WFS with 90% flux to WFS… not much left for CONICA (10%)  hard for NB filters & spectroscopy
Usually (always ?) self-reference  hard to get a (real) PSF
Extended objects  hard to get a sky (even with jittering)

6. Circinus
HST &
NACO J, Ks
combined images

7. What/where is the coronal region in an AGN ?
What: region of high density gas where lines of high ionization (IP > 50 eV) species are excited
Where: very close to the ionization source (UV X-ray), BLRNLR & farther away
(photoionized by the nuclear continuum or excited by fast (v>300 km/s) shocks)
Coronal lines can be used to directly pinpoint the location of the AGN, and measure a (parsec-scale) size

8. Ionization Potential vs line width of the forbidden lines
An example: 1H (Sy1)
(Rodriguez-Ardilla et al., ApJ 2003)
Line
IP eV
FWHM km/s
[Si VI]
167
650
[Fe XI]
262
1000
[Fe XIII]
331
1600

9. Why use [Si VII] 2.48 µm ? Already detected in NGC1068
Our sample: Circinus, ESO428+G014, NGC3081
[Si VI] µm is contaminated by H2 1-0 S(3) µm
[Si VII] is very strong

10. NACO images of Circinus
Coronal emission shows:
Extended (resolved) emission (10 pc diameter)
Hot dust mixed with CLR & NLR
FWHM:
0.12"
2.42 µm continnum [Si VII] 2.48 µm line

11. Where the CLR spots the true nucleus & the apex of the H cone
Astrometry of [Si VII] vs HST H
True color image with
HST 8140 Å
NACO J & K bands
[Si VII] 2.48µm line emission
on top of HST H image

12. NACO images of ESO428 Coronal region shows:
A bright unresolved peak (size 10 pc)
FWHM:
4.3 pixels
= 0.12"
same on stars into the field & PSF
[Si VII] 2.48µm line emission
2.42µm continuum emission

13. H vs [Si VII]
ESO NGC3081

14. More to come… Survey has 4 objects but already…
2 objects have shown the possibilities of:
Localization of the central source of the AGN
Measure size of [Si VII]-CLR (limit of NLR)
Trace cone illumination
Relation with luminosity of the central engine?
Fast shocks (v300 km/s) along the radio jet?