出版社:SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要:Our aim is to study the polarization of thermal dust emission to see if the alignment of grain
by radiative torques could explain the observed relation between the degree of polarization and
the intensity in dense cores. Predictions are made for polarimetry observations with the Planck
satellite. Our results are based on model clouds derived from MHD simulations of magnetized
turbulent flows, while the continuum radiative transfer problem is solved with Monte Carlo methods
in order to estimate the three-dimensional distribution of dust emission and the radiation field
strength affecting the grain alignment. The influence of grain alignment efficiency is examined in
the calculated polarization maps. We are able to reproduce the P/I-relation with the grain alignment
by radiative torques. The decrease in intrinsic polarization and total emission means that
sub-mm polarimetry carries only little information about the magnetic fields in dense cores with
high visual extinction. The interpretation of the observations will be further complicated by the
unknown magnetic field geometry and the fact that what is observed as individual cores may, in
fact, be a superposition of several density enhancements. According to our calculations, Planck
will be able to map dust polarization reliably when AV exceeds ∼ 1m.