Are you looking to communicate with some of those authors through their agents, or are you looking for representation?
If the first one, you would do better to contact them through their publishers; if the second, I can't imagine that there would be a separate listing for "agents of popular authors." I don't think you would be thrown back entirely on dumb luck, though, since a lot of authors maintain an online presence at their own websites or on writing forums, and you could ask them who their agents are. That said, a lot of the time top agents are not looking to take on new clients, especially if those clients are unpublished writers. You might be better off looking for agents who represent a few midlist writers -- experienced agents who are nevertheless interested in new clients and new authors. Where luck would come in to it would be in contacting somebody really good about the time that they are setting up their own agency (having worked at some other big agency before, or being an industry professional moving from something like editing to agenting) while they are still interested in new clients.
(But you don't want an agent who may be willing to sign you, but is then too busy with the big-name authors to spare much time or attention representing you. Better to have someone that editors know, yet who will actually be sending out your manuscript.)