6dF Workshop, May MASS 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)

6dF Workshop, May 2002 Too Many Targets! Our sample: Secure detections in J, H and K. J-K>2. 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.

6dF Workshop, May 2002 Optically Selected AGN 2MASS Type 2 AGN 2MASS Type 1 AGN Composite Spectra

6dF Workshop, May 2002 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 B J <19 or r F <18 (to give us a fighting chance of getting redshifts and IDs). Unfortunately, only 25% of candidates (around 2000 sources) meet these limits.

6dF Workshop, May 2002 Candidates to be observed with 6dF Candidates too faint for 6dF

6dF Workshop, May 2002 Two Incompletenesses The 6dF sample will be large, but incomplete for two reasons. 1) We’ve missed the optically fainter sources. 2) We’re 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.

6dF Workshop, May 2002 Science Goals This survey will be used for many things. I’ll give two examples: High-Z AGN from SIRTF Mapping the inner regions of AGN.

6dF Workshop, May : 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 z=2. It should find more than 10 5 of them! Deeper SIRTF surveys, covering smaller areas, should detect a few hundred of our sources out to z>4.

6dF Workshop, May 2002 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.

6dF Workshop, May 2002 A Feature at 1 micron. Wavelength Flux Radiation from Accretion Disk. Thermal Radiation from Dust We are selecting based on red colours between these two wavelengths. Wavelength corresponding to the sublimation temperature of dust

6dF Workshop, May 2002 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.

6dF Workshop, May 2002 The payoff? If we can get this technique to work, it gives us: Samples of tens of thousands of z=1.6 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,

6dF Workshop, May : Probing the structure of AGN partially 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.

6dF Workshop, May 2002 Toy Model Normal blue AGN when viewed from this angle. Red 2MASS AGN when viewed from here.

6dF Workshop, May 2002 Or alternatively… Normal blue AGN

6dF Workshop, May 2002 Or alternatively… Red 2MASS AGN

6dF Workshop, May 2002 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 AGN’s spatial structure.

6dF Workshop, May 2002 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.

6dF Workshop, May 2002