Improved methods for simulating nearly extremal binary black holes
Abstract
Astrophysical black holes could be nearly extremal (that is, rotating nearly as fast as possible); therefore, nearly extremal black holes could be among the binaries that current and future gravitationalwave observatories will detect. Predicting the gravitational waves emitted by merging black holes requires numericalrelativity simulations, but these simulations are especially challenging when one or both holes have mass m and spin S exceeding the BowenYork limit of S/{{m}^{2}}=0.93. We present improved methods that enable us to simulate merging, nearly extremal black holes (i.e., black holes with S/{{m}^{2}}\gt 0.93) more robustly and more efficiently. We use these methods to simulate an unequalmass, precessing binary black hole (BBH) coalescence, where the larger black hole has S/{{m}^{2}}=0.99. We also use these methods to simulate a nonprecessing BBH coalescence, where both black holes have S/{{m}^{2}}=0.994, nearly reaching the NovikovThorne upper bound for holes spun up by thin accretion disks. We demonstrate numerical convergence and estimate the numerical errors of the waveforms; we compare numerical waveforms from our simulations with postNewtonian and effectiveonebody waveforms; we compare the evolution of the black hole masses and spins with analytic predictions; and we explore the effect of increasing spin magnitude on the orbital dynamics (the socalled ‘orbital hangup’ effect).
 Publication:

Classical and Quantum Gravity
 Pub Date:
 May 2015
 DOI:
 10.1088/02649381/32/10/105009
 arXiv:
 arXiv:1412.1803
 Bibcode:
 2015CQGra..32j5009S
 Keywords:

 General Relativity and Quantum Cosmology
 EPrint:
 18 pages, 18 figures