Cosmic rays and the magnetic field in the nearby starburst galaxy NGC 253 III. Helical magnetic fields in the nuclear outflow

Abstract

Context. Magnetic fields are good tracers of gas compression by shock waves in the interstellar medium. These can be caused by the interaction of star-formation driven outflows from individual star formation sites as described in the chimney model. Integration along the line-of-sight and cosmic-ray diffusion may hamper detection of compressed magnetic fields in many cases.