VLBA Observations of HI in the Archetype Compact Symmetric Object
  B2352+495
  B2352+495 is a prototypical example of a Compact Symmetric Object (CSO). It
has a double radio lobe symmetrically located with respect to a central flat
spectrum radio core (the location of the AGN) and has a physical extent of less
than 200 pc. In this work we report VLBA observation of 21 cm HI absorption
toward B2352+495 to investigate the properties of this remarkable radio source,
in particular, to explore whether the radio emission can be confined by
circumnuclear material (frustration scenario) or whether the source is likely
to be young. We confirmed the two HI absorption features previously detected
toward B2352+495 - a broad line nearly centered at the systemic velocity of the
galaxy and a narrow redshifted component. The atomic gas from the broad
absorption component is likely associated with circumnuclear material,
consistent with the current paradigm of clumpy HI distribution in toroidal
structures around supermassive black holes.
