Optically faint radio sources: reborn AGN?

We have discovered eight relatively strong radio sources that have no optical counterparts. A NIR follow-up has detected faint (17-20 mag) host galaxies in all targets. In general, the radio properties are similar to those observed in 3CRR sources but the optical-radio slopes are consistent with moderate to high redshift (z < 4) GHz-peaked spectrum sources. Our results suggest that these are galaxies whose black hole has been recently re-ignited into activity but that retain large-scale radio structures, signatures of previous AGN activity.