Binary Black Holes. Deirdre Shoemaker Center for Relativistic Astrophysics School of Physics Georgia Tech

Transcription

1 Binary Black Holes Deirdre Shoemaker Center for Relativistic Astrophysics School of Physics Georgia Tech

2 NR confirmed BBH GW detections LIGO-P v12 Abbott et al. 2016a, PRL 116, an orbital frequency of 75 Hz without contact. more, the decay of the waveform after it peaks is tent with the damped oscillations of a black hole to a final stationary Kerr configuration. Below, we a general-relativistic analysis of GW150914; Fig. the calculated waveform using the resulting source eters. Detect merger of BBHs Interpret source parameters Detectors Gravitational-wave astronomy exploi ple, widely separated detectors to distinguish grav waves from local instrumental and environmental provide source sky localization from relative arriv and to measure wave polarizations. The LIGO si operate a single Advanced LIGO detector [32], fied Michelson interferometer (see Fig. 3) that m gravitational-wave strain as a difference in length thogonal arms. Each arm is formed by two mirr ing as test masses, separated by Lx = Ly = L = A passing gravitational wave effectively alters lengths such that the measured difference is Lx Ly = h(t)l, where h is the gravitation strain amplitude projected onto the detector. Thi ential length variation alters the phase difference Test of general relativity in strong regime What next?

3 What will we learn next Gravitational waves can teach us about the central engine of the binary What can the merger reveal about gravity? Dynamics of horizon near merger... imprinted on GW?

4 Binary Black Holes GR 1: Conference on the role of gravitation in physics, University of North Carolina, Chapel Hill [January 18-23, 1957] The 2-body problem of binary black hole took decades and supercomputers Pretorius Binary inspiral and merger Phys.Rev.Lett. 95 (2005) RIT and NASA Moving Punctures Method Campanelli, Lousto, Zlochower Phys.Rev.Lett. 96 (2006) Baker, Centrella, Choi, Koppitz, van Meter Phys.Rev.Lett. 96 (2006)

5 Numerical Relativity Waveforms GT public catalog of a few hundred BBH simulations with many processing systems at einstein.gatech.edu/catalog SXS public catalog of a few hundred long BBH simulations and some extremely spins at black-hole.org RIT catalog at cargo.rit.edu Precessing-Spin: Unequal-Mass (197 simulations) Precessing-Spin: Equal-Mass (127 simulations) q = m 1 m 2 cos 1L cos 2L 1.0

6 NR used to model waveforms EOBNR (Buonanno et al 2007) Phenom (Ajith et al 2007) Direct comparisons (LIGO Scientific Collaboration and Virgo Collaboration & )

7 Provides a Map Input initial mass and spin values, formula predicts final mass, spin and recoil (Healy et al PRD 2014 & Barausse, et al APJ 2012) 2 parameters 15 parameters inspiral: well understood from post-newtonian merger: Nonlinear, requires NR ringdown: understood from perturbation theory

8 Is the GW remnant an Einstein Black Hole? Consistency of inspiral - merger - ringdown Measured frequency and decay in the damped sinusoidal data after peak and it was consistent with Kerr BH Need multiple quasi-normal modes for no-hair tests HARD! Exponentially damped

9 Test GR Binary Black-Hole Configuration Fully predict NR waveforms (precession, eccentricity, higher order modes) Develop experience in nonlinear alternate theories (Healy et al, Yunes et al) QNM q=2, 100 Mpc, 350 M London et al PRD 2014

10 Using GWs to probe Horizon Simple Precession ( q=4, a1 = 0.6 = a2 ) Can we understand how a horizon looses its hair? Can we correlate the outgoing radiation to what is happening at the horizon using its multipoles (Ashtekar, Campiglia & Shah)? Courtesy of Abhay Ashtekar

11 Challenges Ahead Just begun to explore strong gravity in the universe Understanding GR physics necessary for tests of gravity Unique opportunity to explore black hole horizons Exciting times ahead