How did the Japanese surrendered?

The First Atomic bomb was dropped on the city of Hiroshima on 6 August 1945 was called 'Little Boy'. As a result ,about 8000.0 civilians died. On 9 August 1945,the City of Nagasaki was bombed and about 45000 people died.The Atomic Bomb used was called 'Fat Man'.In the next few months ,about 50000 civilians died of Radiation Poisoning. After the Atomic Bombs were dropped, the Japanese surrendered shortly.