UTG AA on scary turn vs. loose passive

Just over halfway through the field of a 2200-person tournament.

Party Poker No-Limit Hold'em Tourney, Big Blind is t50 (10 handed) internettexasholdem.com

MP1 (t3535)
MP2 (t2475)
MP3 (t1020)
CO (t1760)
Button (t2700)
Hero (t4520)
BB (t563)
UTG (t2912)
UTG+1 (t2085)
UTG+2 (t90)

Preflop: Hero is SB with A[img]/images/graemlins/club.gif[/img], A[img]/images/graemlins/heart.gif[/img].
<font color="#666666">1 fold</font>, UTG+1 calls t100, <font color="#666666">1 fold</font>, MP1 calls t100, <font color="#666666">4 folds</font>, <font color="#CC3333">Hero raises to t475</font>, <font color="#666666">1 fold</font>, UTG+1 calls t400, MP1 calls t400.

Flop: (t1525) 7[img]/images/graemlins/spade.gif[/img], 6[img]/images/graemlins/heart.gif[/img], 9[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
<font color="#CC3333">Hero bets t1200</font>, UTG+1 folds, MP1 calls t1200.

Turn: (t3925) T[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(2 players)</font>

Hero ???

The flop was scary enough, but the turn killed me. What's my action here? Check/fold? Bet out? If so, how much?

Eliminating JJ-AA, since he didn't raise preflop, what can I beat? The only hands he just calls with on the flop are TT, 99, 88, 77, 66, Ax of spades, all of which beat me.

This is less of a post about playing against a chaser, and perhaps more about betting to get information (as well as keeping up your level of aggression) while not committing yourself.

Villain had ~1900 on the turn, but there was also ~4000 in the pot on the turn. If I bet 1/4 pot (half of his stack) and he pushes, I have to call, yes?

If he had a bigger stack, what would be the play?