I'm not really sure how to phrase the question but I've never learned how historians publish their research. As an example I hear books cited on here all the time in fact that's pretty much all that was cited.
But for something like physics on a physics equivalent of r/askhistorians if you cited "A brief history of time" you'd be looked at pretty funny.
Do historians have like just straight papers like other sciences do? Or is most historical research put into books for the general public?
/u/Jan_van_Bergen has admirably addressed papers and journal articles.
A book-length work of academic history is usually called a monograph. It's not at all the same thing as A Brief History of Time, and it's distinct from many history books produced for a popular audience. A monograph is basically a journal article on steroids. Both are primarily arguments, not narratives, in that they seek to do more than simply recount a sequence of events, but where a paper or journal article is generally narrowly focused, book-length works of history can go into far more detail and provide greater context. Many historians' first books are cleaned-up, expanded versions of their Ph.D dissertations, to give you some idea of the amount of time and research that goes into it.
As to why you see books referenced here more than other historical resources? I don't know that they are, but I can give you several reasons why. You may be seeing references to journal articles or working papers, but are mistaking them for books because most of us write short, informal bibliographies. For another, many users reading AH don't have access to academic journals, so it's easier to recommend books, which are available on Amazon or at first rate libraries, to a lay audience. Finally, for a lot of purposes, monographs are just better/easier/more useful. Very often historians will write a journal article on a subject, then expand on it and eventually publish their research as a book.
Yes, historians write papers. There are a large number of journals, probably the most important in the United States is the American Historical Review, which is published by the American Historical Association. But there are literally hundreds of other journals dedicated to specific focuses, both locally, nationally, and internationally oriented.
Historians also present papers at conferences, workshops, colloquia, and public lectures. For example, the Annual Meeting of the American Historical Association, the program for the 2016 edition you can find here, is the largest meeting of historians in the United States.
As for why there only seem to be books sourced here, I cannot venture a guess. I'm not even sure that's accurate, but hopefully someone else might have insights there.