The VLA/ALMA Nascent Disk And Multiplicity (VANDAM) Survey of Orion Protostars. V. A Characterization of Protostellar Multiplicity

We characterize protostellar multiplicity in the Orion molecular clouds using ALMA 0.87~mm and VLA 9~mm continuum surveys toward 328 protostars. These observations are sensitive to projected spatial separations as small $\sim$20~au, we consider source up 10$^4$~au potential companions. The overall fraction (MF) companion (CF) for protostars 0.30$\pm$0.03 0.44$\pm$0.03, respectively, considering from 20 10$^4$~au. MFs CFs corrected contamination by unassociated young stars a probabilistic scheme based on surface density of around each protostar. separation distribution whole is double peaked inconsistent with solar-type field stars, while Flat Spectrum consistent stars. statistics distributions Perseus star-forming region those Orion. Based observed peaks Class 0 at $\sim$100~au $\sim$10$^3$~au, argue that multiples $<$500~au likely produced both disk fragmentation turbulent migration, $\ga$10$^3$~au result primarily fragmentation. also find MFs/CFs may rise between 100 10$^3$~au regions high YSO density. This finding be evidence migration companions $>$10$^3$~au $<$10$^3$~au, some 10$^3$ must (or become) unbound.