1. Supermassive Black Hole Growth from Cosmological N-body Simulations Miroslav Micic Kelly Holley-Bockelmann Steinn Sigurdsson Tom Abel Want more info? See astro-ph/0703540

2. Original goal: approach SMBH merger rates ‘from the opposite direction’ of EPS EPS-derived BH merger rates (per year) 0.1 – 100 Haehnelt 94 1 - 100 Menou et al 01 10 Sesana et al 04 15 - 350 Wyithe + Loeb 03 15 Rhook + Wyithe 05

3. How binary black holes meet and merge O(10 -5 ) pc Galaxy mergerBHs bound O(10 6 ) pc Dynamical friction O(10) pc 3-body scatteringGravitational radiation O(10 8 ) yr> O(10 10 ) yr!**> O(10 10 ) yr!* * not anymore…thanks to excision and AMR ** in a static spherical galaxy with permanent ejections and no resonances

4. 10 Mpc 3 from z=40-0 with 2 Mpc refined sphere M low = 5.6 x 10 7 M  r low =4 kpc N=2 x 10 6 M high = 8.9 x 10 5 M  r high =2 kpc N=5 x 10 6 The nuts and bolts:

5. Zooming into a group-sized volume of the universe  matter = 0.3  baryon = 0.045  dark energy = 0.7 n=1  8 = 0.9 h=0.7 Micic, HB, and Sigurdsson

6. Strategy: Pop III seeds and fast, efficient mergers identify all the halos at z=20, and seed those with M > few 10 7 M  with 200 M  BHs continue seeding new halos until z~12 (Pop III star formation squelched by UV background…) Trace the evolution of halos and their embedded BHs from z = 20-0. Assume that BHs merge once the halos merge. Explore three accretion schemes: –Dry mergers only –Salpeter accretion excited by at least 4:1 mergers. –Salpeter accretion excited by M 1 :M 2 < 10:1 mergers.

7. Sgr A* M 31

8. Max black hole merger rate is ~ 55 per year Low mass ratio, ~ 1000 M  BH mergers most abundant overall High mass ratio ~ 1000 M  mergers dominate 2<z<6  ULXs?

9. Intermediate and Supermassive BH Growth BH merger rates ~55 per year Forming a 10 6 M  SMBH requires major merger gas accretion To form a 10 7 M  SMBH must also enlist gas accretion during minor mergers Largest SMBH is in place by z= 6, thereafter growth by mergers only (AGN era  LISA era?) Lots of rogue IMBHs in a Milky Way-sized halo!

10. A gravitational wave implication ‘new’ IMBH-SMBH merger source with rates > O(10) per year Next paper: Can LISA be used as a tool to constrain BH growth mechanisms?

11. …and a surprise: BH mass a product of environment a few isolated halos have extremely underweight bhs

12. Following the leads with better dynamics gravitational wave kicks! proper treatment of dynamical friction How robust is this merger rate? Explore rogue black hole dynamics within Milky Way halo Smaller volume, better resolved simulation – 1 pc resolution with on the fly BH mergers Smooth accretion – tidal disruption + capture and inspiral Do those BHs in the isolated halos stay vastly underweight? How does this relate to downsizing? Cosmic variance -- several realizations of same volume (~10 5 CPU hrs) Suppression mechanisms

13. Ho et al 2003 Spitballing: Is there a variable spread in M-sigma? Largest SMBHs require ‘all’ accretion mechanisms + kicks inefficient (early growth) IMBHs have many formation/growth channels+ kicks efficient