If it is ash, you will need to identify how strong it is and how hard the wood is. This is because I have seen big, old ash trees cut down that had wood that was starting to get brash and go bad, even though the tree looked healthy, possibly dying of just old age in other words, or possibly EAB. If it is good, hard wood, it is most likely white ash. But to me, the heartwood in that log looks a lot bigger than any whiteash I've seen. It almost looks like a type of hickory. But if it is ash, you won't need to chase a ring - just debark and take off any corky sapwood layer it might have. The first good, hard ring should be your back. You can also make a heartwood ashbow if you so desire. I don't know that it would be any better though. But white ash, at least all that I've seen, typically does have thick rings, like up to .5" thick so that would be normal.
I'm not sure or not if this is white ash, but that's what you would want out of the native US ashes. Green isn't as good at all for a self-bow.
White ash would have a strong and hard ring. If you put a rasp to it it should not be all that quick or easy to file if it is strong and healthy white ash.
CP