Another when to fold AK hand

I had been playing a little 25NL when I caved and converted over to HEM. I wanted to give myself a bit of time to get used to the HUD. An interesting hand came up while I was there at the Rush table.

Given the PF action, what else can my 2 opponents have? AK is clearly a far easier hand to fold than KK or QQ!

Full Tilt Poker $0.10/$0.25 No Limit Hold'em - 9 players
The Official DeucesCracked.com Hand History Converter

UTG+1: $13.14
UTG+2: $7.08
MP1: $17.20
Hero (MP2): $72.03
CO: $17.84
BTN: $25.00
SB: $50.71
BB: $5.16
UTG: $12.21

Pre Flop: ($0.35) Hero is MP2 with As Kc
UTG calls $0.25, UTG+1 calls $0.25, UTG+2 calls $0.25, 1 fold, Hero raises to $1.60, CO calls $1.60, 1 fold, SB raises to $5.04, 4 folds, Hero calls $3.44, CO raises to $17.84 all in, SB calls $12.80, 1 fold

Flop: ($41.72) Kd Jc 9s

Turn: ($41.72) 4s

River: ($41.72) 6d

Final Pot: $41.72
CO shows Ad Ac (a pair of Aces)
SB shows Qh Qs (a pair of Queens)
CO wins $39.64
(Rake: $2.08)