No AGN evidence in NGC1614 from deep radio VLBI observations
  We present deep dual-band 5.0 and 8.4GHz European VLBI Network (EVN)
observations of NGC1614, a local luminous infrared galaxy with a powerful
circumnuclear starburst ring, and whose nuclear engine origin is still
controversial. We aim at detecting and characterizing compact radio structures
both in the nuclear region and in the circumnuclear ring. We do not find any
compact source in the central 200pc region, setting a very tight 5 sigma upper
limit of $3.7\times10^{36}$erg s$^{-1}$ and $5.8\times10^{36}$erg s$^{-1}$, at
5.0 and 8.4GHz, respectively. However, we report a clear detection at both
frequencies of a compact structure in the circumnuclear ring, 190pc to the
north of the nucleus, whose luminosity and spectral index are compatible with a
core-collapse supernova, giving support to the high star formation rate in the
ring. Our result favors the pure starburst scenario, even for the nucleus of
NGC1614, and shows the importance of radio VLBI observations when dealing with
the obscured environments of dusty galaxies.
