TPTK v unknown turn raise

Since your unknown opponent seems to be pretty agressive, A9 is somewhat of an unlikely hand for him to cold call a UTG raise with. AQ is also somewhat unlikely because he almost has to cap the flop on that board and he didnt. So he most likely has AK, AJs, or a set of 9's. Only one of these likely possibilities scares you. I three bet or at the very least turn passive and call him down.