1. The Cosmic Density and Distribution of Relativistic Iron Lines David R. Ballantyne Center for Relativistic Astrophysics, School of Physics, Georgia Tech 2010, ApJ, 708, L1

2. Motivation Relativistic Fe K  lines are v. important for probing the physics of the inner accretion flow One of the few probes of SMBH spin Fabian, et al. (2002)

3. Motivation (II) Accurate measurement of broad Fe K lines over a wide range of luminosity and z is one of the principle science goals of IXO Spin evolution of SMBHs in the universe

4. Important Questions How common are intense Fe K lines like that exhibited by MCG-6? Does the EW depend on L and z? The relative small number of decent detections of broad lines in local AGNs typically have EWs <~ 100 eV. Nandra et al. (2007)

5. Where do the Fe K lines come from?

6. Ross & Fabian (1993), Ross et al. (1999), Ballantyne et al. (2001), Ross & Fabian (2005)

7. The Fe K EW Depends on: Photon-index  Fe abundance A Fe Ionization parameter ξ Reflection fraction R (Ignored here: time-dependent effects, e.g., Ballantyne & Ross 2002, Ballantyne et al. 2005) Ballantyne et al. 2002

8. Survey Results: Metallicity Fe II/Hβ  L/L Edd 0.7 ; Netzer & Trakhtenbrot (2007)

9. Survey Results: Photon Index  = 0.58(log(L/L Edd ) +1) + 1.99 ; Risaliti et al. (2009)

10. Survey Results: Ionization Parameter ξ  log(L/L Edd ) ; Inoue et al. (2007)

11. Other Ingredients Ueda et al. (2003) HXLFNetzer (2009) Type 1 AGN SMBH mass function at z=0.15 Labita et al. (2009a) show that M BH (max)  z 0.3

12. The Fe K EW Function Ballantyne (2010)

13. Sky Density of Fe K Lines Ballantyne (2010) If R=1, on average, then the most common Fe K EWs should be <~ 100 eV A 1 deg 2 survey by IXO should uncover ~ 200 AGNs with EWs > 100 eV between z=0.05 and z=0.5

14. How to Look for Spin Evolution Ballantyne (2010, in prep) Including narrow lineNo narrow line