ISOCAM Survey of 3C galaxies

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Hot Dust in Radio-Loud AGNs
Wolfram Freudling Space Telescope European
Coordinating Facility

• ISOCAM Survey of 3C galaxies
• Questions
• How do SEDs of various AGNs types differ?
• Are dust SEDs consistent with Unified Schemes?
• What heats the dust (AGN vs SB contribution)
• What do we expect at higher redshifts?
• Publications Freudling, Siebenmorgen, Haas,
  2003, ApJ Letters 599, 13 Siebenmorgen,
  Freudling, Krügel, Haas, 2003, AA, submitted

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ISOCAM 3C Survey
Siebenmorgen, Freudling, Krügel, Haas, 2003, AA,
submitted

• 88 fields in ISOCAM archive include 3C source
• All fields homogenously co-added and calibrated
• About 50 NLRGs, 25 QSOs, 25 BLRGs
• 71 3CR sources detected
• In 60 of them evidence for dust

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ISOCAM Images of 3C Sources
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ISOCAM pixel size

• HST imaging by Martel et al, 1999, ApJS 122, 88

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Results SEDs
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Mean SEDs
Type 1 Type 2
Freudling, Siebenmorgen, Haas 2003, ApJ Letters
599, L13
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Dust Heating in AGNs
Model 1 (e.g. Farrah et al. 2003, MNRAS 345,
585 Rowand-Robinson 2000, MNRAS 316, 575)
SB heats local dust clouds
Cool dust ? 50K
AGN heats dust torus
Hot dust ? 300K
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HST imaging of Galactic Nuclei
Martel et al. 2000, ApJS 130, 267
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Dust Heating in AGNs
Model 2 (AGN effects throughout host galaxy)
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Spherical Dust model

• Model parameters
• radius
• AGN luminosity
• extinction Av

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Mean SEDs
Type 1 Type 2
Freudling, Siebenmorgen, Haas 2003, ApJ Letters
599, L13
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Radius of dust sphere

• ?
• Best fit radius2 kpc

? Best fit radius4 kpc
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Conclusions 1

• AGNs can heat dust throughout the host
• The presence of cold dust does not necessarily
  imply a SB component
• ? do not use SEDs to identify starburst
  contribution to dust heating

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Differences between AGN and SB heating
Hard radation by AGN distroys PAHs
Siebenmorgen et al. 2003
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Mean SEDs of local (zlt1) AGNs
ISO data suggest that dust throughout the
host is heated by the central engine
Type 1 Type 2
SEDs predict
PAH spectra
Freudling, Siebenmorgen, Haas 2003, ApJL 599, L13
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PAH spectra by AGN type
ISOPHOT spectra of PG QSOs by Haas et al. 2003
AA 402, 87
ISOPHOT spectra of four 3CR sources extracted
from archive Freudling et al. 2003
ISOPHOT spectra of Seyfert 2s by Clavel et al.
2000 AA 357, 839
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Dust in high-z QSOs
Redshifted local QSOs Freudling et al. 2003, ApJL
599, L13
High-z QSOs Bertoldi et al. 2003, AA 406, L55
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Summary Conclusions

• ISOCAM detected most of the 3C sources within its
  field of view, mostly because of dust emission.
• There is a clear correlation between the AGN type
  and the peak of the SEDs
• type 1 peak around ??40?m
• 2 ??100?m
• PAHs emmission is stronger in type 2 AGNs with
  same dust luminosity as their type 1 counterparts
• AGN can heat dust throughout the host

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The End
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The End
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Dust Heating in AGNs
Model 2 (AGN effects throughout host galaxy
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Fitting Procedure
Plot data
synchrotron
stellar
dust
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Example M82
log L 10 Av 25 R2 kpc
Krügel Siebenmorgen, 1994, AA 288, 929 log L
10.5 Av25 R1 kpc
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NO
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0.05 lt z lt 0.4