An extremely prolific supernova factory in the buried nucleus of the
  starburst galaxy IC 694
  Context. The central kiloparsec of many local Luminous Infra-red Galaxies are
known to host intense bursts of massive star formation, leading to numerous
explosions of core-collapse supernovae (CCSNe). However, the dust-enshrouded
regions where those supernovae explode hamper their detection at optical and
near-infrared wavelengths. Aims. We investigate the nuclear region of the
starbust galaxy IC 694 (=Arp 299-A) at radio wavelengths, aimed at discovering
recently exploded CCSNe, as well as to determine their rate of explosion, which
carries crucial information on star formation rates, the initial mass function
and starburst scenarios at work. Methods. We use the electronic European VLBI
Network to image with milliarcsecond resolution the 5.0 GHz compact radio
emission of the innermost nuclear region of IC 694. Results. Our observations
reveal the presence of a rich cluster of 26 compact radio emitting sources in
the central 150 pc of the nuclear starburst in IC 694. The large brightness
temperatures observed for the compact sources indicate a non-thermal origin for
the observed radio emission, implying that most, if not all, of those sources
are young radio supernovae (RSNe) and supernova remnants (SNRs). We find
evidence for at least three relatively young, slowly-evolving, long-lasting
RSNe (A0, A12, and A15) which appear to display unusual properties; suggesting
that the conditions in the local circumstellar medium (CSM) play a significant
role in determining the radio behaviour of expanding SNe. Their radio
luminosities are typical of normal RSNe, which result from the explosion of
Type IIP/b and Type IIL SNe. All these results yield support for a recent (less
than 10-15 Myr) instantaneous starburst in the innermost regions of IC 694.
