Diffuse Synchrotron Emission Associated with the Starburst in the
  Circumnuclear Disk of NGC 1275
  Recent Atacama Large Millimeter/submillimeter Array (ALMA) observations found
a positive correlation between the mass of dense molecular gas in the
circumnuclear disks (CNDs) and accretion rate to the active galactic nuclei
(AGNs). This indicates that star formation activity in the CNDs is essential
for triggering the accretion of mass to AGNs. Although the starburst-driven
turbulence is a key mechanism for the transfer of angular momentum and the
resultant mass accretion from the CND scale to the inner radius, the
observational evidence is lacking. We report the
very-long-baseline-interferometry (VLBI) detection of the diffuse synchrotron
emission on a scale of several tens-pc coinciding spatially with the molecular
gas disk recently discovered by ALMA observations in NGC~1275. The synchrotron
emissions are most likely resulted from the relativistic electrons produced by
the supernova explosions. This is an unambiguous evidence of the star formation
activity in a CND. The turbulent velocity and the scale height of the CND
predicted from the supernova-driven turbulence model agree with the
observations, although the model-predicted accretion rate disagrees with the
bolometric luminosity. This might indicate that additional mechanisms to
enhance the turbulence is required for the inner disk. We discuss the
multiphase nature of the CND by combining the information of the CO emission,
synchrotron emission, and free-free absorption.
