The Super-alfvénic Model of Molecular Clouds: Predictions for Zeeman Splitting Measurements

We present synthetic OH Zeeman splitting measurements of a super-Alfvénic model of molecular clouds. We select dense cores from synthetic 13CO maps computed from the largest simulation to date of supersonic and super-Alfvénic turbulence. The synthetic Zeeman splitting measurements in the cores yield a relation between the magnetic field strength, B, and the column density, N, in good agreement with the observations. The large scatter in B at a fixed value of N is partly due to intrinsic variations in the magnetic field strength from core to core. We also compute the relative mass-to-flux ratio between the center of the cores and their envelopes, Rμ, and show that super-Alfvénic turbulence produces a significant scatter also in Rμ, including negative values (field reversal between core center and envelope). We find Rμ < 1 for 70% of the cores, and Rμ < 0 for 12%. Of the cores with |BLOS| > 10 μG (values that could be detected observationally), 81% have Rμ < 1. These predictions of the super-Alfvénic model are in stark contrast to the ambipolar drift model of core formation, where only Rμ > 1 is allowed. Subject headings: ISM: magnetic fields — stars:fromation — MHD — radiative transfer