Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session H12: Relativistic Simulations of Compact Binaries |
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Sponsoring Units: GGR Chair: David Brown, North Carolina State University Room: Hyatt Regency Jacksonville Riverfront City Terrace 8 |
Sunday, April 15, 2007 8:30AM - 8:42AM |
H12.00001: Simulations for the merger of black hole-neutron star binary in full general relativity. Koji Uryu, Masaru Shibata Simulations for the merger of black hole-neutron star (BH-NS) binary are performed successfully in full general relativity, starting from the initial data in quasi-equilibrium circular orbit. A new method is developed for calculating the puncture BH-NS initial data in circular orbits. Then, the BH-NS binary is evolved using the moving puncture method. For the initial data, we assumed that the BH has no spin, while the NS has the corotating velocity field and follows the $\Gamma$-law equations of state with $\Gamma=1$. The BH mass is chosen to be $M_{\rm BH}\approx 3.2 M_\odot$, and the NS mass to be $M_{\rm NS}\approx 1.4 M_\odot$ with relatively large radius $\sim 14$km. It is found that the neutron star is tidally disrupted near the last orbit, $\sim 80\%$ of the NS mass is swallowed into the BH, and the disk mass after the merger in this model is estimated as small as $\sim 0.3 M_\odot$. The result indicates that the BH-disk system with the disk mass $\sim M_\odot$ is not formed after the merger of non-spinning BH and NS binary, although a disk of mass $\sim 0.1 M_\odot$ is a possible outcome. [Preview Abstract] |
Sunday, April 15, 2007 8:42AM - 8:54AM |
H12.00002: Efficient binary black hole simulations Wolfgang Tichy, Pedro Marronetti, Bernd Bruegmann, Jose Gonzalez, Mark Hannam, Sascha Husa, Ulrich Sperhake We present results of simulations of spinning black hole binaries in circular orbits, which cover several orbits as well as the merger and ringdown phases. These simulations are performed using a moving punctures implementation within the BAM code. This code uses moving mesh refinement boxes. It is so efficient that our simulations can be performed on dual processor workstations. In particular, we compute the initial and final ADM mass and angular momentum and show their dependence on grid size and resolution. In addition, we discuss quality control curves and constraint satisfaction. [Preview Abstract] |
Sunday, April 15, 2007 8:54AM - 9:06AM |
H12.00003: Compact body interactions and boson stars Carlos Palenzuela, Ignacio Olabarrieta, Luis Lehner, Steve Liebling The two body problem in General Relativity is studied in this work by solving numerically Einstein Equations. The approach chosen consists of modeling (at least) one of the compact object by means of a boson star, which is a self-graviting configuration of (complex) scalar field. We present studies of binary systems involving one of these boson stars with another companion compact object. The results illustrate rich phenomenology with interest consequences on the radiated gravitational waves. [Preview Abstract] |
Sunday, April 15, 2007 9:06AM - 9:18AM |
H12.00004: Spin Dynamics in Black-Hole Binaries Yosef Zlochower, Manuela Campanelli, Carlos Lousto, Badri Krishnan, David Merritt We present results from recent simulations of merging black-hole binaries with individual spins unaligned with the orbital angular momentum. These binaries show spin and orbital plane precession, as well as flips in the direction of the spin between the individual spins and the final remnant spin. This latter effect is thought to be responsible for the sudden change in the direction of the jets observed in some AGN. [Preview Abstract] |
Sunday, April 15, 2007 9:18AM - 9:30AM |
H12.00005: Advances in Black-Hole Mergers: Spins and Unequal Masses Bernard Kelly, James van Meter, Sean McWilliams, Dae-Il Choi, Joan Centrella, William Darian Boggs, John Baker The last two years have seen incredible development in numerical relativity: from fractions of an orbit, evolutions of an equal-mass binary have reached multiple orbits, and convergent gravitational waveforms have been produced from several reserach groups and numerical codes. We are now able to move our attention from pure numerics to astrophysics, and address scenarios relevant to current and future gravitational-wave detectors. Over the last 12 months at NASA Goddard, we have extended the accuracy of our HahnDol code, and used it to move toward these goals. We have achieved high-accuracy simulations of black-hole binaries of low initial eccentricity, with enough orbits of inspiral before merger to allow us to produce hybrid waveforms that reflect accurately the entire lifetime of the BH binary. We are extending this work, looking at the effects of unequal masses and spins. [Preview Abstract] |
Sunday, April 15, 2007 9:30AM - 9:42AM |
H12.00006: Applying Numerical Relativity Results to Massive Black Hole Binary Observation Sean McWilliams Coalescing binary black holes may be the most promising candidate sources for gravitational wave detection for both ground- and space-based interferometers, due to the strength of their emitted signals. In order to maximize the probability of detection, extract physical parameters from detected waveforms, and make predictions which can be compared with measurements as a test of general relativity, accurate templates for the gravitational radiation emission must be available. Post-Newtonian approximations may be used to predict the characteristics of an emitted waveform, but those approximations lose accuracy and eventually become aphysical as the binary reaches the end of the inspiral phase approaching merger. The field of numerical relativity is now capable of the accurate calculation of this last phase of coalescence, when the black holes finish their inspiral and merge to form a single perturbed Kerr black hole. We present applications of the waveform as a template for use in data analysis for the ground-based interferometer LIGO, its planned upgrade Advanced LIGO, and the space-based interferometer LISA. [Preview Abstract] |
Sunday, April 15, 2007 9:42AM - 9:54AM |
H12.00007: Reducing junk radiation and eccentricity in binary-black-hole initial data Geoffrey Lovelace, Harald Pfeiffer, Duncan Brown, Lee Lindblom, Mark Scheel, Lawrence Kidder Numerical simulations of binary-black-hole (BBH) collisions require initial data that satisfy the Einstein constraint equations. Several well-known methods generate constraint-satisfying BBH data, but the commonly-used simplifying assumptions lead to undesirable effects. BBH data typically assume a conformally flat spatial metric; this leads to an initial pulse of unphysical ``junk'' gravitational radiation. Also, the initial radial velocity of the holes is often neglected; this can lead to significant eccentricity in the holes' trajectories. This talk will discuss efforts to reduce these effects by constructing and evolving generalizations of the BBH initial data of Cook and Pfeiffer (2004). By giving the holes a small radial velocity, the eccentricity can be greatly reduced (although the emitted waves are largely unaffected). The junk radiation for flat and non-flat conformal metrics will also be compared. [Preview Abstract] |
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