924

Poster

The Role of Magnetic Fields in the Interstellar Medium of Irregular Galaxies

Amanda A. Kepley¹, S. Muehle², J. Everett³, E. Wilcots³, E. Zweibel³, T. Robishaw⁴, C. Heiles^5
1University of Virginia, ²JIVE, Netherlands, ³University of Wisconsin, ⁴University of Sydney, Australia, ⁵University of California--Berkeley.

22. Normal Galaxies, Elliptical Galaxies, Spiral Galaxies, Dwarf Galaxies, Irregular Galaxies

Irregular galaxies are the present day analogs of the high redshift building blocks of galaxies like the Milky Way. The shallow potential wells of irregular galaxies makes their interstellar medium a chaotic system prone to disruption by star formation, interactions, and mergers. An important, but oft-overlooked component of the interstellar medium of irregulars is their magnetic field. Previous observations suggest that irregulars have a wide range magnetic field strengths and properties. To increase the number of irregulars with detailed observations of their magnetic fields, we have observed three irregular galaxies with the VLA and WSRT: NGC 4214, NGC 1569, and NGC 1156. The magnetic field of NGC 1569 is shaped almost entirely by the outflow of gas from this galaxy, but the central magnetic field in this galaxy may be a dominant source of pressure in this galaxy. The magnetic field of NGC 4214 is mostly random and is not a dominant source of pressure. NGC 1156 is similar in size to NGC 4214, but has a much more extended radio continuum envelope. We will place these fields into the context of the interstellar medium of these galaxies. Finally, we will draw conclusions on the role of magnetic fields in irregular galaxies in general.