SIMBAD references

Utilizing Planck polarized dust emission maps at 353 GHz and large-area maps of the neutral hydrogen (H I) cold neutral medium (CNM) fraction (f_CNM), we investigate the relationship between dust polarization fraction (p₃₅₃) and f_CNM in the diffuse high latitude ($\left|b\right|\gt 30^\circ $) sky. We find that the correlation between p₃₅₃ and f_CNM is qualitatively distinct from the p₃₅₃-H I column density (N_H i_) relationship. At low column densities (N_H i_ < 4 × 10²⁰ cm^–2) where p₃₅₃ and N_H i_ are uncorrelated, there is a strong positive p₃₅₃-f_CNM correlation. We fit the p₃₅₃-f_CNM correlation with data-driven models to constrain the degree of magnetic field disorder between phases along the line of sight. We argue that an increased magnetic field disorder in the warm neutral medium (WNM) relative to the CNM best explains the positive p₃₅₃-f_CNM correlation in diffuse regions. Modeling the CNM-associated dust column as being maximally polarized, with a polarization fraction p_CNM ∼ 0.2, we find that the best-fit mean polarization fraction in the WNM-associated dust column is 0.22p_CNM. The model further suggests that a significant f_CNM-correlated fraction of the non-CNM column (an additional 18.4% of the H I mass on average) is also more magnetically ordered, and we speculate that the additional column is associated with the unstable medium. Our results constitute a new large-area constraint on the average relative disorder of magnetic fields between the neutral phases of the interstellar medium, and are consistent with the physical picture of a more magnetically aligned CNM column forming out of a disordered WNM.