That's not a good turn card, but he didn't preflop raise so it's probably safe to say he doesn't have AA - maybe 88 or A5, but since he's slightly loose, I'd say AK, AQ, or maybe Ax are just as likely and if you're passive image and he's aggressive, he could be trying to push you off a hand with QQ, JJ, TT, or even air. I say shove.