There's a rather old answer in the FAQ about this (by a [deleted] user) the directly addresses the question.

u/restricteddata has also answered a few questions related to this in detail.

• Is it true that Japan offered to surrender on the condition that the Emperor remained in power, prior the the bombing of Hiroshima?
• Were the Japanese preparing to surrender before the dropping of the atomic bombs? (along with u/BCoopActual.

Restricted also has a article titled about why Nagasaki was bombed, but I'm not sure it's permitted to link to a user's blog.

As I am not a historian, I'm not sure if the scholarship has changed about this recently, so could certainty have more to be said!