Speaker
Priscilla Frisch
(University of Chicago)
Description
Before reaching the Earth, galactic cosmic rays must traverse nearby
partially ionized low density interstellar clouds. The evolved
superbubble known as Loop I appears to order the cloud kinematics and
the magnetic field of the interstellar medium (ISM) within tens of parsecs.
The direction of the nearby interstellar magnetic field (ISMF) that is
found from starlight polarized in the local interstellar medium is
approximately parallel to the local surface of the Loop I shell that dominates the northern hemisphere. Nearby
interstellar clouds flow through the local standard of rest with a
direction that is perpendicular to the ISMF direction, to within the
uncertainties. The direction of the ISMF helping to shape the
heliosphere is found from the center of the Ribbon of energetic
neutral atoms discovered by the Interstellar Boundary Explorer (IBEX)
spacecraft, and is close to the local field direction found from
polarization data. Open questions remain. The structure of the
distant parts of Loop I is filamentary and there is evidence for
filamentary structure in the local ISM. The role of flux freezing in
local gas is unknown. The polarity of the magnetic field is not clear.
Summary
The connections between the local interstellar magnetic field,
local clouds, and the evolved Loop I supernova remnant are reviewed.
Primary author
Priscilla Frisch
(University of Chicago)
