Is there any way to get reference of object which is instantiated when object gets recognized ?
Do you mean which object target was recognized or a reference to its augmentation/drawable GameObject?
To get the recognized object target's name, add a listener to an ObjectTrackable's OnObjectRecognized(ObjectTarget target) callback (scripting reference). target.Name will give you which object was recognized and is tracked.
To get a reference to the target's augmentation/drawable GameObject, also add a listener to the ObjectTrackable's event callback (or the equivalent ImageTrackable event callback) and retrieve the GameObject via target.Drawable (scripting reference).