Against an unknown I would call down with any queen, I would fold if i had JJ, or 9x.

However you said this player plays solid postflop this changes things significantly. IMO here is the hand range of a typical postflop solid player given the turn action. I would put him on AA,KK,QQ,99,33,22,AQ,KQ since he may 3bet preflop with all these hands. I dont think he can have a hand like QJ,JJ,TT or 9x since going for the checkraise would be too risky becuz there are too many bad river cards that can kill him in case you check behind, and plus he is also less likely to have the best hand relative to your range. I dont see him checkraising this turn on a draw either since he would most likely bet the turn and hope you fold since he has been the aggressor so far.

So against a solid postflop player I think you need to tighten up your calling down requirements significantly. The fact that he did see you fold Aces does complicate things, this fact should make you loosen up your calling down requirements. KQ is the minimum hand I would call down with in this situation against a solid postflop player.

Notice that KQ is the bottom of the range I put the solid player on, which means based on my read calling down with this hand doesnt make sense, but since he did see you fold aces, and theres always a 5-10% hes bluffing/semibluffing, and theres always a chance my read is wrong, calling down with KQ is acceptable IMO.