http://arxiv.org/abs/1708.04063
We present the projected Rayleigh statistic (PRS), a modification of the classic Rayleigh statistic, as a test for non-uniform relative orientation between two sets of pseudo-vector fields. This gives an effective way of investigating whether polarization is preferentially parallel or perpendicular to filaments in the interstellar medium, for example; there are other potential applications in astrophysics, e.g. when comparing small-scale orientations with larger-scale shear patterns. We compare the efficiency of the PRS against histogram binning methods that have previously been used for characterising the relative orientations of gas column density structures with the mag- netic field projected on the plane of the sky. We specifically examine data for the Vela C molecular cloud, where the column density is inferred from Herschel submil- limetre observations, and the magnetic field from observations by the Balloon-borne Large-Aperture Submillimetre Telescope in the 250-, 350-, and 500-{\mu}m wavelength bands. We find that the projected Rayleigh statistic has greater statistical power than approaches that bin the relative orientation angles, and hence this circular statistic makes more efficient use of the information contained in the orientation data.
D. Jow, R. Hill, D. Scott, et. al.
Tue, 15 Aug 17
23/59
Comments: 11 pages, 7 figures