What made antigone think that she could defy authority in her city?

I don't believe that Antigone thought her actions would go unpunished. In my opinion, she knew there would be repercussions, and she knew how extreme her punishment might possibly be. None-the-less, we might also look at it the other way. Antigone is Creon's niece.... she is also his future daughter-in-law. Even more, his son Haemon loved her.... would she be granted a reprieve? Unfortunately, Creon believes he must make an example of her.... and in the end..... she dies for what she believes.