暗物质晕的密度分布的动画演示

1. 暗物质晕的密度分布的动画演示

2. Stars/DM swallowed in BH’s Loss Cone vt<4GM/cr • Zhao, Haehnelt, Rees (2002)

3. DM Annihilation Plateau

4. Dark Matter Cusps  Spikes • Explored first by Gondolo & Silk (1999) • If assume: • A 1Msun BH accretes to 2 x106 Msun at exact centre of dark halo • DM has a divergent DF at centre (any Zhao profile |dρ/dr|>0) • Adiabatic growth (fix DF) • Then DM contracts • to ρ = r-a law ( a=2.25-2.5 > 1.5). • annihilation signal from centre Lxx ~ ρ2 dr3 nearly divergent (truncated by BH horizon) • Lack of emission from centre falsifies neutralinos • of certain Mx & σv (Gondolo 2000, Bertone, Sigl, Silk 2001) • Clearly needs checking with a more realistic theory for BH seeds and growth.

5. Astrophysical limits on neutralinos Bertone, Sigl, Silk 2001

6. Introducing off-centred BH seeds • We reexamine assumptions, show many likely outcomes • Off-centred seed > 1000Mo • Dynamical friction too slow for smaller seed • Seed removes particles in cusp, makes DF finite/lower • Merger Growth • Modest contraction • Slow Growth after recentre • DM Density  r-0.5 • Contract only a factor of 1000 (103 Mo to 106 Mo) • Bulge Growth • Baryon dominated NOW • Modest Compress dark matter Ullio, Zhao, Kamionkowski (2001)

7. Bulge Compression • Prada et al. 2004

8. Recent Merger: no spike • Merritt, Milosvic et al.

9. Stellar Relaxation • Gnedin & Primack • Merritt ρ ~ r -2.45 ρ ~ r -1.5

10. Mass of neutralinos • Gianfranco & Merritt

11. Gas in Mini-halo  first star  first IMBH • 3 x105 Mo Mini-halos form at z=22 (t=0.15Gyr) Rvir=64pc=100Rc, Vvir=5km/s • 3 x104 Mo in gas of T=1500K, no metals • Dense core of the cloud Collapse to 100-1000Mo star • Unstable  SNa or BH • Gas is cleared out in 4Myrs • Attracts a r-1.5 DM spike (Zhao & Silk 2005) • IMBH/Spike recentre in Mini-halo Abel et al.

12. Minihalos in Milky Way • 1012 Msun MW halo contains N=104 minihalos • Innermost miniholes can spiral to MW centre in a Hubble time • despite stripping. • Seed to form SMBH? • 99% beyond 1kpc MW halo • weak tides unable to strip minihalos • Annihilation observable as • extended sources when passing the disk • point-like sources in halo Zhao & Silk 2005, PRL

13. IMBH crossing disk • Bondi-Hoyle accretion (Lacey & Ostriker) b=2GM/V2 =0.0002pc (M/1000), dM/dt=ρ V π b2 =0.001 Msun/Gyr n L= ε c2 dM/dt =1 Lsun (M/1000)2 n • Well below Ledd =5 106 Lsun (M/1000) • Typically 1 BH in MW disk at any given time. • n=0.3 for warm ionized gas, filling 30%, L<0.1Lsun • n=600cm-3 for H2 clouds, fill 0.3%, L<300Lsun. • n=40 for cold HI clouds, filling factor 2%, L<20 • Hard to detect

14. Mini-halo crossing disk • Baltz & Wai • e diffuse in B • Inv. Compton

15. Earth-Mass-Halo passing disk stars • stripped to tidal stream when passing stars? Diemand et al. Zhao, Taylor, Silk, Hooper (in prep)

16. Other effects • Cusp destruction in Elliptical • BH kicked during merger • Browning motion • Will the first minihalo survive intact? • Is there enough time to grow to massive hole? • Will later arrived minihalos and miniholes speed relaxation, fill loss cone?

17. Orbits around BH • DM Potential constrained