Abstract:
We report the detection of circular polarization in the compact radio jet of the nearby spiral galaxy M81 (M81*). The observations were made with the Very Large Array at 4.8 and 8.4 GHz and circular polarization was detected at both frequencies. We estimated a value of m_c=0.54% at 8.4 GHz and m_c=0.26% at 4.8 GHz for the fractional circular polarization. The spectrum of the circular polarization is inverted which is unusual for AGN. We also detected no linear polarization in M81* to a level of 0.01% implying that the source has a very high circular-to-linear polarization ratio found so far only in Sgr A*, the central radio source in our Galaxy. This further supports the idea that M81* is a scaled-up version of Sgr A* and suggests that the polarization properties are intrinsic to the two sources and are not caused by a foreground screen in the Galaxy.
Paper: Available in PostScript and (AAS)LaTex. Please send an email request to hfalcke@mpifr-bonn.mpg.de for a preprint.
Other publications can be found here.
Questions: Heino Falcke, hfalcke@mpifr-bonn.mpg.de