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LOFAR discovers mysterious structures in our Galaxy

Submitter: Vibor Jelic
Description: Recent observations with LOFAR revealed a bewildering variety of structures in polarization in several fields at high Galactic latitudes. The most interesting features are seen in the 3C196 field, a primary window of the LOFAR-Epoch of Reionization project.

A colour composite image of polarized radio emission observed in 3C196 field is shown in figure. Different colours represent emission detected at different Faraday depths. Straight and long filamentary structures are visible parallel to the Galactic plane. They are located somewhere within the Local Bubble. A system of linear depolarization canals (black stripes) is also conspicuous in the image.

A follow up analysis of this data showed a surprising, yet clear, correlation between the filamentary structures detected with LOFAR and the magnetic field orientation, probed by the Planck dust polarization maps (Zaroubi et al. 2015). This finding points to a common, yet unclear, physical origin in this specific area in the sky. A filamentary structure is aligned with the magnetic field of our Galaxy and probably consists of both gas and dust. This calls for further multi-frequency analysis and observations of a much larger area around this field.

more info:
Jelic et al., 2015, A&A, in press
Zaroubi et al., 2015, MNRAS Letters, 454 (1), L46-L50
Copyright: V. Jelic
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