Consider the inverse Fourier transform of $\frac{1}{\sqrt{\xi_1} + \xi_2}$. My question is, how can we conclude about the decay properties, support and smoothness of the inverse Fourier transform? I understand that this is not exactly a research-level question, but the question appears a bit hard. Any help is appreciated.
Edit: Initially I had asked about the inverse Fourier transform of $\frac{1}{\sqrt{\xi}}$, which was answered by the comments below. I looked up the formulae for complex powers of Euclidean norm of $(\xi_1, \xi_2)$, but the methodology there does not seem to apply to the edited question.