http://arxiv.org/abs/1706.09786
The common envelope binary interaction remains one of the least understood phases in the evolution of compact binaries, including those that result in Type Ia supernovae and in mergers that emit detectable gravitational waves. Only few simulations have been carried out to date and often their results are taken at face value. In this work we continue the detailed and systematic analysis of 3D hydrodynamic simulations of the common envelope interaction aimed at understanding the reliability of the results. Our first set of simulations replicate the 5 simulations of Passy et al. (a 0.88Msun, 90Rsun RGB primary with companions in the range 0.1 to 0.9Msun) using a new AMR gravity solver implemented on our modified version of the hydrodynamic code {\sc Enzo}. The higher resolution achieved around the RGB core and the companion results in smaller final separations. We also carry out 5 identical simulations but with a 2Msun primary RGB star with the same core mass as the Passy et al. simulations, isolating the effect of the envelope binding energy. With a more bound envelope all the companions in-spiral faster and deeper though relatively less gas is unbound. We additionally find that for the 2Msun primary with a 0.6Msun companion, the higher the resolution, the smaller the final separation and the larger the fraction of unbound envelope gas. This suggests that simulations with a heavier companions may not be entirely converged and that interactions between companions and a 2Msun RGB primary may readily end in a merger. We finally discuss our simulations in the context of similar simulations from the literature that include the effects of recombination energy.
R. Iaconi, O. Marco, J. Passy, et. al.
Fri, 30 Jun 17
46/65
Comments: Submitted to MNRAS. Authors welcome comments
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