I guess awake isn't the right word. Say I have a multi-page, large AngularJs application. Is the controller of a page that isn't active right now awake? For example, if I wanted to call a function of that controller with $rootScope.$broadcast, would it be listening for that signal or would it only recieve that signal when I go to the part of the page that requires that controller? Sorry if this makes not much sense.
Controllers have instances per usage, that means that angularJS will make an instance of some controller only if it is in use.
If you need to pass data from one controller to other, the common way is to use some service. As service are singletons which created on the first inject.
So, you can inject a service in one controller (page), invoke some method on it, which will change some data on it, then navigate to other page, in this page, inject the service, and use the data on it.