2MASS Selected AGN with 6dF

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2MASS Selected AGN with 6dF

• Paul Francis (ANU)
• Roc Cutri, Brant Nelson, David Kirkpatrick
  (IPAC/CALTECH)
• M. Skrutskie (U. Virginia)
• P. Smith, G. Schmidt, D. Hines (U. Arizona)
• J. Huchra, B. Wilkes (SAO)

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Too Many Targets!

• Our sample
• Secure detections in J, H and K.
• J-Kgt2. If we picked a bluer limit, the sample
  would be more complete, and much larger, but the
  contamination would be larger.
• 17,000 candidates meet these criteria.
• Based on the 700 spectra obtained to date,
  roughly 12,000 will be AGN.

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Composite Spectra
Optically Selected AGN
2MASS Type 1 AGN
2MASS Type 2 AGN
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Observing Strategy

• We will use 6dF to obtain spectra of as many of
  these southern candidates as possible.
• We will pick all currently unobserved candidates
  which have either BJlt19 or rFlt18 (to give us a
  fighting chance of getting redshifts and IDs).
• Unfortunately, only 25 of candidates (around
  2000 sources) meet these limits.

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Candidates too faint for 6dF
Candidates to be observed with 6dF
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Two Incompletenesses

• The 6dF sample will be large, but incomplete for
  two reasons.
• 1) Weve missed the optically fainter sources.
• 2) Were only picking AGN with extreme J-K
  colours. This may be the tip of the iceberg.
• Spectroscopy with larger telescopes will be
  needed to assess these problems, and is underway.

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Science Goals

• This survey will be used for many things. Ill
  give two examples
• High-Z AGN from SIRTF
• Mapping the inner regions of AGN.

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1 SIRTF

• The SWIRE SIRTF Legacy program will map 25 square
  degrees at 3.6, 4.5, 5.8 and 8.0 microns.
• It should be easily capable of detecting the
  rest-frame J and K-band flux of objects like our
  AGN out to z2.
• It should find more than 105 of them!
• Deeper SIRTF surveys, covering smaller areas,
  should detect a few hundred of our sources out
  to zgt4.

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The Problem

• The problem will be distinguishing between these
  AGN and the very large number of foreground
  sources.
• In principle, photometry in the near-IR, combined
  with the SIRTF mid-IR data should allow us to
  separate AGN and determine good photometric
  redshifts.
• This is possible because of the observed spectral
  break between the rest-frame optical and near-IR.

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A Feature at 1 micron.
We are selecting based on red colours between
these two wavelengths.
Wavelength corresponding to the sublimation
temperature of dust
Thermal Radiation from Dust
Flux
Radiation from Accretion Disk.
Wavelength
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Where does 6dF come in?

• 6dF will provide us with a sample with which to
  develop and verify these photometric techniques.
• It also provides the zero-redshift reference
  survey against which the vast high-z ones will be
  compared.
• For this, we will need multi-colour optical
  photometry for the 6dF AGN hopefully the
  Southern Sky Survey will provide this.

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The payoff?

• If we can get this technique to work, it gives
  us
• Samples of tens of thousands of z1.6 AGN with
  good photometric redshifts, to study the
  evolution of LSS.
• The Mother of all gravitational lensing
  surveys, vast, well defined, and relatively
  immune to dust. This will give us very strong
  constraints on the dark matter distribution in
  galaxies and clusters,

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2 Probing the structure of AGN

• Two lines of evidence suggest that our view of
  the inner regions of the 2MASS AGN is partially
  obscured.
• The polarisation
• The different extinction of the optical
  continuum, of the X-ray emission and of the IR
  emission.
• This partial obscuration might be caused by the
  torus or some other obstacles.

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Toy Model
Normal blue AGN when viewed from this angle.
Red 2MASS AGN when viewed from here.
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Or alternatively
Normal blue AGN
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Or alternatively
Red 2MASS AGN
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Tomography

• Whatever it is that is doing the partial
  obscuration, it provides us with a way of
  separating out the different emitting regions of
  the AGN.
• A combination of models with spectra of a very
  large, statistically well understood sample may
  enable us to use this obscurer as a straight
  edge, so we can reconstruct the AGNs spatial
  structure.

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Conclusions

• 6dF will get us spectra of a few thousand IR
  selected, low redshift AGN.
• These are AGN like no others
• This will not be a complete sample, but its
  biasses are well determined.
• It should be the key to understanding forthcoming
  mid-IR surveys.

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The End