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AGN Clustering. by Sean Lake for Astro 278 2012. Obligatory Outline Slide. Context: basic AGN review. How clustering studies can help. Clustering quantities: ξ(r), w p (r p ). What these quantities tell us. Clustering studies done. Conclusions. Basic Facts. Luminosity: ≥10 5 L ☉
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AGN Clustering • by • Sean Lake • for Astro 278 2012
Obligatory Outline Slide • Context: basic AGN review. • How clustering studies can help. • Clustering quantities: ξ(r), wp(rp). • What these quantities tell us. • Clustering studies done. • Conclusions.
Basic Facts • Luminosity: ≥105 L☉ • Size: < 1 pc (variability) • Location: center of galaxies • Punchline: we believe this phenomenon to arise from the accretion disk around a supermassive black hole. • Mystery: how does the gas get there?
The Role of Environment • Each of the three scenarios on the right have different relative clustering w.r.t. background galaxies • Can also test Unification Figure 2 from Alexander and Hickox 2011
but What we Really Measure.... • Galaxy / dark matter (DM) halo positions are biased: • That bias is a function of characteristic halo mass • Thus correlation length, r0, gives a measure of halo mass. Figure 5 from Sheth et al. 2001
Regular Galaxy Interlude Figure 5 from Coil et al. 2009
X-ray AGN Clustering Figures 10 and 11 from Coil et al. 2009
IR AGN Clustering Demonstrates that there is no difference between obscured & unobscured AGN Figure 7 from Hickox et al. 2011
Summing it Up Figure 5 from Alexander and Hickox 2011
Summary • Clustering ∈ environment • Measures the influence of outside galaxies in feeding BHs • Differentiates feeding mechanisms based on BH type. • Clustering allows tests of selection techniques (also, potentially, unification)