I just finished grad school, earning a Phd in mathematics. Currently I do not know if I want to continue my academic career or not, but in the meantime I have written an article containing some of the results of my thesis and I would like to submit it to a journal for publication.
The journal I have chosen (published by Springer) asks for academic affiliation: can I say my academic affiliation is the university where I completed grad school, although I do not work there anymore? If not, is it possible to get a paper published without an academic affiliation? What do you suggest me to do?