Hi @wooj, welcome here,
Dask Array are lazy, they are not computed until asked by the user. So a Dask Array is always a handle to something to compute in the future. You can preview it’s shape and how it chunked, but if you want the data, you need to ask.
In this small example, this won’t be a problem though, just get the Array (and convert it to a local Numpy array) with:
x_delta.compute()