Radio continuum and X-ray emission from the most extreme FIR-excess
  galaxy NGC 1377: An extremely obscured AGN revealed
  Galaxies which strongly deviate from the radio-far IR correlation are of
great importance for studies of galaxy evolution as they may be tracing early,
short-lived stages of starbursts and active galactic nuclei (AGNs). The most
extreme FIR-excess galaxy NGC1377 has long been interpreted as a young dusty
starburst, but millimeter observations of CO lines revealed a powerful
collimated molecular outflow which cannot be explained by star formation alone.
We present new radio observations at 1.5 and 10 GHz obtained with the Jansky
Very Large Array (JVLA) and Chandra X-ray observations towards NGC1377. The
observations are compared to synthetic starburst models to constrain the
properties of the central energy source. We obtained the first detection of the
cm radio continuum and X-ray emission in NGC1377. We find that the radio
emission is distributed in two components, one on the nucleus and another
offset by 4$"$.5 to the South-West. We confirm the extreme FIR-excess of the
galaxy, with a $q_\mathrm{FIR}\simeq$4.2, which deviates by more than
7-$\sigma$ from the radio-FIR correlation. Soft X-ray emission is detected on
the off-nucleus component. From the radio emission we estimate for a young
($<10$ Myr) starburst a star formation rate SFR$<$0.1 M$_\odot$ yr$^{-1}$. Such
a SFR is not sufficient to power the observed IR luminosity and to drive the CO
outflow. We find that a young starburst cannot reproduce all the observed
properties of the nucleus of NGC1377. We suggest that the galaxy may be
harboring a radio-quiet, obscured AGN of 10$^6$M$_\odot$, accreting at
near-Eddington rates. We speculate that the off-nucleus component may be
tracing an hot-spot in the AGN jet.
