This project will investigate the common envelope phase of stellar binaries. The common envelope phase is an important ingredient in the life of binaries that transform them into compact binaries.…

This is a federal grant award to the University of Wisconsin System's Office of Sponsored Programs Division, doing business as the University of Wisconsin-Milwaukee (UWM), in the amount of $334,360.99. The grant was awarded by the National Aeronautics and Space Administration (NASA) to investigate the common envelope phase of stellar binaries, which is an important but poorly understood aspect of binary star evolution.

The research aims to use a new hydrodynamics simulation code to model the physics of common envelope ejection and explore the conditions under which recombination energy in the envelope contributes to its ejection. The project will also develop models to understand optical transients that may result from stellar mergers, as well as the progenitors of gravitational wave-detected massive black hole binary systems. This work is expected to advance the understanding of common envelope evolution and its observed astrophysical effects. The award does not involve any set-asides.

This project will investigate the common envelope phase of stellar binaries. The common envelope phase is an important ingredient in the life of binaries that transform them into compact binaries. IT is believe to be the mechanism by which pretty much all compact binaries form. In spite of its obvious importance, common envelope evolution is still largely an unknown and unconstrained aspect of binary evolution. The PI and collaborators have recently developed a new public moving-mesh hydrodynamics code that would be ideal for numerical simulations of this unconstrained aspect of binary evolution. Using this new code, the PI proposes to integrate realistic physics and initial conditions into IT and explore the physics of common envelope ejection. In particular, the PI will determine over which range in parameter space would recombination energy in the envelope contribute substantially to its ejection. Additionally, the PI will use the physics glean from these full 3-d numerical simulations to develop a simple 1-d model for these events. Finally, motivated by observations of intermediate luminosity optical transients that believe (in part) to be a result of stellar mergers and by the recent detection of gravitational waves from merging massive black hole binaries, the PI will develop models to explore the physics of these optical transients and explore the parameter space to find the systems that may be the progenitors of the observed massive black hole binaries. The work performed by the PI and his group will be important in understanding the physics of common envelope evolution and its observed effects either through optical transient search or gravitational wave detections. The work will help understand observations from space-base high energy satellites like fermi, chandra, XMM-newton, and swift and ground based optical transient facilities and gravitational wave detectors. IT will also be useful in understanding future observations and detectors from space-based gravitational wave observatories like lisa.