Menashe Unger, a Journalist and authority on Hasidism. died here yesterday at age 69. He was a writer for The Day-Jewish Journal, a Yiddish daily here. Born in Austria-Hungary, and a onetime student at the University of Vienna and the Hebrew University, he was author of “Rabbi Israel ben Eliezer Baal Shem-Tov,” a biography of the founder of the Hasidic movement. Other books by Mr. Unger, a member of the Hasidic movement, were “Social Origins of Hasidism,” “The Book of Martyrs” and “Happy Holidays, Children,” all in Yiddish.