Hydrodynamics of binary coalescence. 1: Polytropes with stiff equations of state

Abstract

view Abstract Citations (152) References (73) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Hydrodynamics of Binary Coalescence. I. Polytropes with Stiff Equations of State Rasio, Frederic A. ; Shapiro, Stuart L. Abstract We have performed a series of three-dimensional hydrodynamic calculations of binary coalescence using the smoothed particle hydrodynamics (SPH) method. The initial conditions are exact polytropic equilibrium configurations with $\gam > 5/3$, on the verge of dynamical instability. We calculate the emission of gravitational radiation in the quadrupole approximation. The fully nonlinear development of the instability is followed until a new equilibrium configuration is reached. We find that the properties of this final configuration depend sensitively on both the compressibility and mass ratio. An {\em axisymmetric} merged configuration is always produced when $\gam\lo2.3$. As a consequence, the emission of gravitational radiation shuts off abruptly right after the onset of dynamical instability. In contrast, {\em triaxial\/} merged configurations are obtained when $\gam\go2.3$, and the system continues to emit gravitational waves after the final coalescence. Systems with mass ratios $q\ne1$ typically become dynamically unstable before the onset of mass transfer. Stable mass transfer from one neutron star to another in a close binary is therefore probably ruled out. The maximum amplitude $h_{max}$ and peak luminosity $L_{max}$ of the gravitational waves emitted during the final coalescence are nearly independent of $\gam$, but depend very sensitively on the mass ratio $q$. Publication: The Astrophysical Journal Pub Date: September 1994 DOI: 10.1086/174566 arXiv: arXiv:astro-ph/9401027 Bibcode: 1994ApJ...432..242R Keywords: Astronomical Models; Binary Stars; Coalescing; Dynamic Stability; Equations Of State; Hydrodynamics; Mathematical Models; Neutron Stars; Nonthermal Radiation; Polytropic Processes; Stellar Interiors; Adiabatic Equations; Gravitational Waves; Mass Transfer; Quadrupoles; Astrophysics; EQUATION OF STATE; HYDRODYNAMICS; INSTABILITIES; RADIATION MECHANISMS: NONTHERMAL; STARS: BINARIES: CLOSE; STARS: INTERIORS; STARS: NEUTRON; Astrophysics E-Print: 27 pages, uuencoded compressed postscript, 16 figures upon request from BEST@sns.ias.edu, IAS-AST-94-4 full text sources arXiv | ADS | Related Materials (1) Part 2: 1995ApJ...438..887R