You can't put him specifically on AT without a ridiculous read; if he boated he boated. You should probably be pushing here. Your position is fine for a limp. I make this limp 90% of the time under these conditions; the hijack is only 2 seats from the button remember so you have good position.

Steve

EDIT: he could have A3 also but theres not much way to tell. I double up or lose it all on this hand, you only have so much time to accumulate chips. Anyone with an ace is giving you all their money here.