You can't without a plugin.
The closest you can achieve without you events getting too complex, is to use a sprite with a circular collision polygon and do something like
// flatten the array
-> Array: set size to (0,1,1)
+ myObject is overlapping circularDetector
+ foreach myObject
-> Array: push myObject.UID in X axis
Then you have the UID of all the object whose collision polygon overlap the circularDetector's one.
The UID is the closest thing you'll have to a "reference" in c2's event sheet system.
Also it's an unperfect solution since your circularDetector won't have a perfect circle has a collision polygon but a... polygon (by default an octogon)
And it's inperfect because it's not really an AABB test but a collision polygon against collision polygon.
But if you set the collision polygon of myObject to bounding box... you'll be closer to what you asked (: