Evidence of a pure starburst nature of the nuclear region of NGC 253
  We present high-resolution spectral line and continuum VLBI and VLA
observations of the nuclear region of NGC 253 at 22 GHz. While the water vapor
masers in this region were detected on arcsecond and milliarcsecond scales, we
could not detect any compact continuum emission with a 5 sigma upper limit of ~
1 mJy. The observations reveal that the water maser emission is not related to
a possible low-luminosity active galactic nucleus but is almost certainly
associated with star-formation activity. Not detecting any compact continuum
source on milliarcsecond scales also questions the presence of a - previously
assumed - active nucleus in NGC 253.
