Imprints of the Local Bubble and Dust Complexity on Polarized Dust Emission
arxiv(2024)
摘要
Using 3D dust maps and Planck polarized dust emission data, we investigate
the influence of the 3D geometry of the nearby interstellar medium (ISM) on the
statistics of the dust polarization on large (80') scales. We test the idea
that the magnetic field in the nearby dust is preferentially tangential to the
Local Bubble wall, but we do not find an imprint of the Local Bubble geometry
on the dust polarization fraction. We also test the hypothesis that the
complexity of the 3D dust distribution drives some of the measured variation of
the dust polarization fraction. We compare sightlines with similar total column
densities and find evidence that, on average, the dust polarization fraction
decreases when the dust column is substantially distributed among multiple
components at different distances. Conversely, the polarization fraction is
higher for sightlines where the dust is more concentrated in 3D space. This
finding is statistically significant for the dust within 1.25 kpc, but the
effect disappears if we only consider dust within 270 pc. The extended 3D dust
distribution, rather than solely the dust associated with the Local Bubble,
plays a role in determining the observed dust polarization fraction on these
scales. This conclusion is consistent with a simple analytical prediction and
remains robust under various modifications to the analysis. These results
illuminate the relationship between the 3D geometry of the ISM and tracers of
the interstellar magnetic field. We also discuss implications for our
understanding of the polarized dust foreground to the cosmic microwave
background.
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