Those papaya plants look very happy! I'll bet it's wonderful to grow them, particularly since I read that their bloom season is year-round!
Papaya trees grow well outdoors in USDA zones 9 and 10.
BUT--
I found out on p. 84 of this book (Growing Tasty Tropical Plants in Any Home, Anywhere) that dwarf papaya can be grown indoors by those of us that do not live in the warmer climes
They taste like a blend of cantaloupe and watermelon? Sign me up! It's on my "to grow list" now!