Arp 299-A: More than "just" a prolific supernova factory
  We present partial results from our monitoring of the nuclear region of the
starburst 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 and starburst scenarios at
work. Two epochs of eEVN observations at 5.0 GHz, taken in 2008, revealed the
presence of a rich cluster of compact radio emitting sources in the central 150
pc of the nuclear starburst in Arp 299A. 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 were young
radio supernovae (RSNe) and supernova remnants (SNRs). More recently,
contemporaneous EVN observations at 1.7 and 5.0 GHz taken in 2009 have allowed
us to shed light on the compact radio emission of the parsec-scale structure in
the nucleus of Arp 299-A. Namely, our EVN observations have shown that one of
the compact VLBI sources, A1, previously detected at 5.0 GHz, has a flat
spectrum between 1.7 and 5.0 GHz and is the brightest source at both
frequencies. The morphology, radio luminosity, spectral index and ratio of
radio-to-X-ray emission of the A1-A5 region allowed us to identify A1-A5 with
long-sought AGN in Arp 299-A. This finding may suggest that both starburst and
AGN are frequently associated phenomena in mergers. Finally, we also note that
component A0, identified as a young RSN, exploded at the mere distance of two
parsecs from the putative AGN in Arp 299-A, which makes this supernova one of
the closest to a central supermassive black hole ever detected.
