SKEWED NEUTRAL HYDROGEN DISTRIBUTIONS AND DIFFERENT MAGNETIC-FIELD SHAPES IN NEARBY SPIRAL GALAXIES

Is the distribution of neutral hydrogen (H I) gas in the disk of a spi ral galaxy linked with the shape of the global magnetic field (B) in i ts interstellar disk? Six spiral galaxies (Milky Way, M 31, M 33, IC 3 42, M 81, and NGC 6946) with well mapped magnetic field and neutral hy drogen distributions are studied here. For these galaxies a preliminar y answer to the question above is positive: a spiral galaxy with regul arly shaped or moderately skewed H I isophotes seems to have a regular axisymmetric azimuthal magnetic field (m(azim) = 0). Conversely, a sp iral galaxy with strongly skewed or extremely skewed H I isophotes see ms to have a beautifully-shaped bisymmetric azimuthal magnetic field ( m(azim) = 1).