"Actors, a core feature in Erlang, are just another library in Scala." - or any other language out there.
EDIT: actors -> the actor model
In the sense in which it is accurate to say that "design patterns are merely patches for missing language features" -- that is, design patterns that are applied as code templates -- anything that can be implemented once as a library is not a design pattern in the language where that is possible.
Perl has an experimental Actor model library threads::lite - https://metacpan.org/pod/threads::lite
For distributed scenarios NServiceBus is a good option although it's a bit different kind of model.
Yes, you can use Akka from Java. Just to show that you don't need something like Scala to implement an actor system.
I confess I haven't used it before though...why use pulsar when I can get away with using akka?