Close stellar and compact object binaries are important to an extremely broad variety of astrophysical phenomena. Yet, most close binaries are not binaries. They are triple systems. Moreover, triple and quadruple systems are common on aggregate, representing roughly 10% and 3% of stellar systems on the sky, respectively. Most importantly, the long-term dynamics of multiple systems is not understood and fully characterized. Very recent advances in our understanding of the Kozai-Lidov resonance (and its extensions) have the chance to dramatically reconfigure our understanding of the production of close compact object and stellar binaries of all types. The investigators are at the forefront of these developments. They suggested that triple systems could produce "prompt" mergers of WD-WD binaries, perhaps leading to the Type Ia supernovae that are observed to immediately follow episodes of star formation. They also showed that mass loss in binaries could instigate the "Eccentric Kozai Mechanism," (EKM) producing close WD and NS-stellar binaries. Finally, and speculatively, they also suggested a triple or quadruple origin for Tycho B, an exceedingly rare low-metallicity A-star at the center of Tycho's supernova remnant that may be a blue straggler. The investigators propose a broad suite of projects aimed at understanding the demographics, evolution, dynamics, and implications of triple and quadruple systems composed of stars and their compact objects. They will do both broad sweeps through parameter space, and focused studies of individual systems. Among the projects they will pursue, they will (1) map the space of the EKM and the Mass-Loss Induced EKM for the first time, (2) calculate the gravitational wave background and foregrounds from eccentric compact object binaries in triple systems, (3) explore the origin of the enigmatic ms-pulsar PSR J1903+0327, (4) attempt to understand the period commensurability observed in the recently discovered doubly-eclipsing quadruple A-star system CzeV343, (5) develop evolutionary scenarios for Tycho B and explore the implications for other Ia remnants, (6) expand the secular dynamics of 3-body systems to higher order, (7) compute the delay-time distribution of Ia supernovae formed from white dwarf-white dwarf mergers in coeval and dynamically formed triple systems, (8) attempt to understand the evolution of massive star triple systems with explosive mass loss and neutron star kicks, and (9) understand if direct compact object collisions can be driven by Kozai-Lidov oscillations.
A significant part of the work will be carried out by graduate and undergraduate students, providing extensive training in cutting-edge scientific research. Results from this research will be broadly disseminated by publication in peer-reviewed journals, conference proceedings, and by the press. In addition, the investigators propose an interesting education and outreach component that targets the public broadly, called "Ask An Astrophysicist!"
