black hole binary mergers: recent developments in numerical relativity first-term presentation by...
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Black hole binary mergers: recent developments in numerical relativity
First-term presentation
By Nikos FanidakisSupervisors: Carlton Baugh, Shaun Cole, Carlos Frenk
13/12/2007
Black hole binary mergers: recent developments in numerical relativity
First-term presentation
By Nikos FanidakisSupervisors: Carlton Baugh, Shaun Cole, Carlos Frenk
13/12/2007
Outline
• Brief introduction to gravitational waves • Black hole (BH) binary mergers in numerical
relativity• Astrophysical implications: recoil kicks• Discussion – conclusions
3
Quantum Fluctuations in the Early UniverseMerging super-massive black holes (SMBHs) at
galactic cores
Capture of BHs and compact stars by SMBH
Merging binary
NSs and BHs in distant
galaxies
NS quakes and
magnetars
Gravitational wave radiation
BH mergers in numerical relativity: 1964-2005
Image courtesy: Kip Thorne
BHs are strong sources of gravitational waves!
A merge of two equal mass BHs releases ~1056
ergs/s Accurate gravitational
waveforms are essential for LISA
First attempt by Hahn – Lindquist (1964): inspiral (!) → merger(??) → ringdown (!)?
BH mergers in numerical relativity: 2005-2007
time
ampl
itu
de
inspiral
merger
ringdown
Baker et al. 2006
1. The technique: “3+1” decomposition 3-d
hypersurfaces. Evolution of hypersurface through
time using 17 nonlinear, coupled differential eqns!
2. The breakthrough (Baker et al. 2006): Fixed “puncture”
representation of the BH Comoving coordinates
Astrophysical implications: recoil kicks
Centrella et al. 2007
Asymmetric BH mergers impart a recoil kick to the final remnant (ejection from host structure?)
Unequal-mass BH merger simulation (Gonzalez et al. 2007):o Initial binary: m1=0.36m2
ukick ~176 km/s Highly-spinning BH merger
simulation (Herrmann et. 2007): o Initial binary: equal-mass BHs with
anti-aligned equal spins
ukick =475 km/s
M-σ relation constraint ≈ 500 km/s If spin not perpendicular to orbital
plane ukick up to 2000 km/s (Campanelli et al. 2007)
Discussion – conclusions
known