Does US Customs and Border Protection have access to Australian?
While CBP doesnt publicize the limits of their database, I believe they do have access to criminal records from the U.S., Canada, Australia, New Zealand, and the United Kingdom. That does not mean you will be denied entry just because you have been arrested. If you are extremely worried, you could apply for a visa instead of using ESTA and bring a certified copy of your criminal record to the visa interview.