The Current Status of

Hypervelocity Stars

Galactic Center Workshop

Shanghai2009 Oct 21

Warren R. BrownSmithsonian – CfA

Collaborators:

Margaret Geller, Scott Kenyon

+850 km/s (!!)

The First Hypervelocity Star

Links to the Black Hole

Ejection Mechanism Observed Properties

Velocity distribution

Spatial distribution

Temporal distribution

Stellar Rotation distribution

Single MBH + binary star (Hills 1988)

Binary MBH + single star(Yu & Tremaine 2003)

Stellar BH + MBH + star(O’Leary & Loeb 2008)

(Sesana et al 2007)

(Levin 2006)

Hansen (2007)Lockmann & Baumgardt (2008)Lopez-Morales & Bonanos (2008)

Latest Results

Brown et al (2009a)

Links to Dark Matter

Brown et al. (2009b)

HVS = Galactic Center origin1. There are unbound stars in halo.

2. MBH in the GC.

3. Stars orbit the MBH.

4. HVSs are B stars.

5. GC full of B stars.

6. Travel times < lifetimes.

7. Nobs = Npredicted.

Heber et al (2008)

but . . .

Runaway B Stars

HVSs

Binary disruption:1. Supernova2. Dynamical

Runaways

Bromley, Kenyon, Brown & Geller (2009)

Runaway vs. HVS

Bromley, Kenyon, Brown & Geller (2009)

Brown et al. (2009b)

Conclusions

1. =

2.

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