(FR) AA - overpair IP vs check raise

Cant fold this. Snap call. Firstly, 9 should be a safe card. Secondly, you can redraw to beat a made flush, either by hiting a higher flush or a full. Thirdly, both of you will be commited for the river with a turn bet of that size. Bet bigger might not get so many calls too.
Dont see many reasons to check back either.

As played the pot is 136.8bb and you need to call 31.8bb which means the required win% to break even is a bit less than 19%.
You have a nut flush draw but also a 9 would give you the nuts (1 extra out) + one of the two aces that are left would give you the best full house.

There is only 1 combo of 99 possible. This villain could call pre with 66 or 22 but he shouldn't, so we maybe could give quite small weight to villain's full houses.

I think as played this is a call vs that turn raise.

I think I kind of like betting here but I'm not completely sure which sizing we should use.

Unless you are 100% positive that villain has 99, you can't fold vs his raise. You are getting enough pot odds to call.

You can still make the nut flush, a full house, and there is also a small chance that villain has a worst hand like TT or JJ. Usually he doesn't but sometimes he does.

Next time bet higher flop and ship river when you consider his stack.