Dispersion of Observed Angles of Submillimeter Polarization in Giant Molecular Clouds

We present submillimeter polarimetric observations of the Giant Molecular Cloud (GMC) NGC 6334, obtained using the Hertz instrument at the Caltech Submillimeter Observatory on Mauna Kea. We obtain constraints on GMC magnetic fields by interpreting these Hertz data together with (a) previously published larger-scale submillimeter polarization maps of the GMCs NGC 6334 and G333.6-0.2 obtained using the SPARO instrument at South Pole, and (b) simulated GMC polarization maps from published magnetohydrodynamic turbulence simulations. The agreement between observations and simulations is good only when the ratio RF :U of fluctuating to uniform field amplitudes lies in the range 0.6 < RF :U < 2.0, and when the ratio RT :K of total magnetic energy (including both uniform and fluctuating components) to turbulent kinetic energy lies in the range 0.9 < RT :K < 1.8. We also compare our results with those obtained by other investigators. Subject headings: ISM: magnetic fields — stars: formation — submillimeter — polarization