We present results of a search for late-time radio emission and Fast Radio Bursts ( FRBs ) from a sample of type-I superluminous supernovae ( SLSNe-I ) .
We used the Karl G. Jansky Very Large Array to observe ten SLSN-I more than 5 years old at a frequency of 3 GHz .
We searched fast-sampled visibilities for FRBs and used the same data to perform a deep imaging search for late-time radio emission expected in models of magnetar-powered supernovae .
No FRBs were found .
One SLSN-I , PTF10hgi , is detected in deep imaging , corresponding to a luminosity of 1.2 \times 10 ^ { 28 } erg s ^ { -1 } .
This luminosity , considered with the recent 6 GHz detection of PTF10hgi in \citet 2019arXiv190110479E , supports the interpretation that it is powered by a young , fast-spinning ( \sim ms spin period ) magnetar with \sim 15 M _ { \sun } of partially ionized ejecta .
Broadly , our observations are most consistent with SLSNe-I being powered by neutron stars with fast spin periods , although most require more free-free absorption than is inferred for PTF10hgi .
We predict that radio observations at higher frequencies or in the near future will detect these systems and begin constraining properties of the young pulsars and their birth environments .