I would like to ask the community where I could apply for a PhD, given some (advanced) topics that I really like. If I ask it on math.se or mathoverflow, I'm afraid that they send me to academia.se, as the question is not a math problem. If I ask it on academia.se, anyway, there are almost no mathematicians, and it's very unlikely to find people in my own subfield.
What can I do about it? Can we make a special tag? Is there already a place where to ask such questions?