If they were recently refinished, they probably are poly. Possibility that they are varnished.
Either way, I would use a No Wax! floor cleaner. Bruce makes a hardwood floor cleaner, and so do other manufacturers. These cleaners have no wax or oil which is important with poly. You don't want to put something on your floor that will make it slippery like oil or wax!
With poly floors, you can clean with a damp (NOT WET) mop.