Mapping the circumnuclear dust in nearby AGN with MIDI

Konrad R.W. Tristram, Klaus MeisenheimerMax-Planck-Institut für Astronomie

Heidelberg, Germany

Collaborators: Walter Jaffe, David Raban, Bill Cotton

22.08.2006 Konrad R. Tristram Page 2

Motivation

• Unified AGN model:Geometrical effects lead to different manifesta-tions (e.g. Seyfert 1 & 2)

• Our goal:Resolve the dust distri-bution directly for nearby AGN

Broad LineRegion

AccretionDisk

ObscuringTorus

Ionisation Cone

Black Hole

22.08.2006 Konrad R. Tristram Page 3

Circinus: the galaxy

• Spiral galaxy SA(s)b, i = ~65°

• RA = 14h 13m, DEC = −65° 20’

• Seyfert type 2

• 4 × 106 M nucleus

• Distance ~4 Mpc → 50 mas ~ 1 pc

• unresolved in MIR

2MASS J, H, Ks colour mosaic

22.08.2006 Konrad R. Tristram Page 4

Circinus: MIDI observations

• The Circinus UV coverage:

21 fringe tracks,

16 photometries

Period 72, 04-02 (U3-U2)Period 73, 04-06 (U3-U2)Period 74, 05-02 (U3-U4)Period 75, 05-05 (U2-U3)Period 77, 06-05 (U2-U3)

-80-60-40-2020406080

u in m

-80

-60

-40

-20

20

40

60

80 v in mU2-U4

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Circinus: total flux

8 9 10 11 12 13Wavelength in µm

0

5

10

15

20

Flu

x in

Jy

Circinus, total flux from all observations

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Circinus: correlated flux

8 9 10 11 12 13Wavelength in µm

0.0

0.5

1.0

1.5

2.0

Flu

x in

Jy

PA= 44°, BL=49.4mPA= 54°, BL=51.1mPA= 57°, BL=51.7mPA= 88°, BL=58.2mPA=120°, BL=62.0mPA=131°, BL=62.4m

Circinus, observed: 2005-02-28

N

22.08.2006 Konrad R. Tristram Page 7

Circinus: modeling

Two blackbody Gaussians:

-200 0 200

-200

0

200

DE

C in

mas

RA in mas 11 µm

Log of model flux distribution at 11µm

Size: σ1 = 9 mas

Ellipticity: ε1 = 0.61

Temperature: T1 = 400 K

Filling factor: f1 = 1.0

Size: σ2 = 42 mas

Ellipticity: ε2 = 0.03

Temperature: T2 = 300 K

Filling factor: f2 = 0.5

Silicate depth: τSiO = 1.3

Position angle: α = 60°

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Circinus: environment

Known geometry

1’’~ 20 pc

O[III] Expected torus configuration

Wilson et al. 2000

22.08.2006 Konrad R. Tristram Page 9

Circinus: model result

RA in mas

DEC in mas

-75-50-25255075

-75

-50

-25

25

50

75

1.9 pc0.4 pc

Dust torus in Circinus supports unified scheme

22.08.2006 Konrad R. Tristram Page 10

Centaurus A (NGC 5128)

• Elliptical galaxy• RA = 13h 25m• DEC = −43° 01’• Radio jet

• 6 × 107 M nucleus

• Distance 3.8 Mpc

→ 53 mas ~ 1 pc• Merger

22.08.2006 Konrad R. Tristram Page 11

Centaurus A: results

8 9 10 11 12 130.0

0.5

1.0

1.5

2.0

Flu

x in

Jy

PA~108°, BL~60.3m

PA~ 37°, BL~45.3m

Total Photometry

Wavelength in µm

N

No dusty torus in Centaurus A

22.08.2006 Konrad R. Tristram Page 12

Conclusions

• Circinus:– small hot and large cold component– orientation perpendicular to ionisation cone

• Centaurus A• Centaurus A– weak extended dust

component– major emitter in MIR:

synchrotron source

• Weaker targets:– hardly resolved

Paranal, February 2005