ALMA's Polarized View of 10 Protostars in the Perseus Molecular Cloud
  We present 870 $\mu$m ALMA dust polarization observations of 10 young Class
0/I protostars in the Perseus Molecular Cloud. At $\sim$ 0.35$"$ (80 au)
resolution, all of our sources show some degree of polarization, with most
(9/10) showing significantly extended emission in the polarized continuum. Each
source has incredibly intricate polarization signatures. In particular, all
three disk-candidates have polarization vectors roughly along the minor axis,
which is indicative of polarization produced by dust scattering. On $\sim$ 100
au scales, the polarization is at a relatively low level ($\lesssim 1\%$) and
is quite ordered. In sources with significant envelope emission, the envelope
is typically polarized at a much higher ($\gtrsim 5\%$) level and has a far
more disordered morphology. We compute the cumulative probability distributions
for both the small (disk-scale) and large (envelope-scale) polarization
percentage. We find that the two are intrinsically different, even after
accounting for the different detection thresholds in the high/low surface
brightness regions. We perform Kolmogorov-Smirnov and Anderson-Darling tests on
the distributions of angle offsets of the polarization from the outflow axis.
We find disk-candidate sources are different from the non-disk-candidate
sources. We conclude that the polarization on the 100 au scale is consistent
with the signature of dust scattering for disk-candidates and that the
polarization on the envelope-scale in all sources may come from another
mechanism, most likely magnetically aligned grains.
