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Mapping the circumnuclear dust in nearby AGN with MIDI. Konrad R.W. Tristram, Klaus Meisenheimer Max-Planck-Institut für Astronomie Heidelberg, Germany Collaborators: Walter Jaffe, David Raban, Bill Cotton. Motivation. Unified AGN model: - PowerPoint PPT Presentation
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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
22.08.2006 Konrad R. Tristram Page 5
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
22.08.2006 Konrad R. Tristram Page 6
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°
22.08.2006 Konrad R. Tristram Page 8
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
