Spectral radius of power graphs on certain finite groups

The power graph of a group G is a graph with vertex set G and two distinct vertices are adjacent if and only if one is an integral power of the other. In this paper we find both upper and lower bounds for the spectral radius of power graph of cyclic group Cn and characterize the graphs for which these bounds are extremal. Further we compute spectra of power graphs of dihedral group D2n and dicyclic group Q4n partially and give bounds for the spectral radii of these graphs.