Is there a tool to visualize the academic citation network around a researcher? I'm looking for a PhD position. Of course I'm reading and following the papers of the field to get to know the community. Is there a tool to visualize a citation/co-author network (or at least a database I could visualize myself)? I have looked into tools like CitNetExplorer and VosViewer. Csauthors.net is also a nice tool, but it is limited to showing only a path between two researchers instead of a full graph.

Essentially, I would like to map all collaborations of the researchers to get a feeling for where the hot spots are and where the niches are.
You might want to have a look at the Web of Science (formerly known as ISI Web of Knowledge). When I started my PhD back in 2008, I used it particularly for visualizing citation networks relevant to my research. I think some time later it became a subscription based service, so the access is not as easy anymore, but a lot of scientific institutions or libraries may provide you the access. I haven't used the Web of Science any more in recent time, so I am not really aware of their capabilities today -- but the description still reads similar to what I remember.