20.07.2013 Views

Black holes: from event horizons to trapping horizons - LUTH ...

Black holes: from event horizons to trapping horizons - LUTH ...

Black holes: from event horizons to trapping horizons - LUTH ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Viscous fluid analogy<br />

Case of future <strong>trapping</strong> <strong>horizons</strong><br />

Definition [Hayward, PRD 49, 6467 (1994)] :<br />

H is a future <strong>trapping</strong> horizon iff θ (ℓ) = 0 and θ (k) < 0.<br />

The generalized Damour-Navier-S<strong>to</strong>kes equation reduces then <strong>to</strong><br />

S Lh Ω (ℓ) + θ (h) Ω (ℓ) = Dκ − D · σ (m) − 1<br />

2 Dθ(h) − θ (k) DC + 8πq ∗ T · m<br />

[EG, PRD 72, 104007 (2005)]<br />

NB: Notice the change of sign in the − 1<br />

2 Dθ(h) term with respect <strong>to</strong> the original<br />

Damour-Navier-S<strong>to</strong>kes equation<br />

The explanation: it is θ (m) which appears in the general equation and<br />

<br />

<strong>event</strong> horizon (m = h) : (m) (ℓ) θ = θ<br />

θ (m) + θ (h) = 2θ (ℓ) =⇒<br />

<strong>trapping</strong> horizon (θ (ℓ) = 0) : θ (m) = −θ (h)<br />

Eric Gourgoulhon (<strong>LUTH</strong>) <strong>Black</strong> <strong>holes</strong>: <strong>trapping</strong> <strong>horizons</strong> CERN, 17 March 2010 29 / 38

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!