Astronomy and Astrophysics – Astronomy
Scientific paper
Dec 2007
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007aas...21111305k&link_type=abstract
American Astronomical Society, AAS Meeting #211, #113.05; Bulletin of the American Astronomical Society, Vol. 39, p.943
Astronomy and Astrophysics
Astronomy
Scientific paper
Magnetic fields are an important component of the interstellar medium (ISM). They provide a source of pressure support, transfer energy from supernovae, are a possible heating mechanism for the ISM, and channel gas flows. Despite the importance of magnetic fields in the ISM, what generates and sustains galactic magnetic fields or how magnetic fields, gas, and stars interact in galaxies is not well understood. The magnetic fields may be especially important in low-mass galaxies like irregulars where the magnetic pressure may be great enough for the field to be dynamically important. Only three irregular galaxies besides the LMC and the SMC have previously observed magnetic field structures. NGC 4449 (Chyzy et al. 2000) and the LMC (Gaensler et al. 2005) both have large-scale fields, while IC 10 and NGC 6822 have mostly random fields (Chyzy et al. 2003). Our goal is to determine what mechanisms generate and sustain large-scale magnetic fields in irregular galaxies and what causes the range of magnetic field structure in irregular galaxies. We have observed the polarized radio continuum emission of four irregular galaxies with the VLA, GBT, and ATCA. Our observations double the number of irregular galaxies with observed magnetic field structure. Here we present results from two of our galaxies: NGC 4214 and NGC 1569. We find that NGC 4214 has a mostly random magnetic field structure, which is not surprising given its weak bar, small size, and high star formation rate. The magnetic field of NGC 1569 has large-scale structure which has been shaped not by a dynamo, but by an outflow generated by the massive star formation rate in this galaxy.
Support for this research has been provided by a GBT Student Support Award, a Wisconsin Space Grant Consortium Graduate Fellowship, and an NSF Graduate Research Fellowship.
Everett John
Heiles Carl
Kepley Amanda A.
Muehle Stefanie
Robishaw Timothy
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