How Is X-ray astronomy useful in space exploration?

In earlier days in the 17th century, people only have an optical telescope. So they have a limitation in using an optical telescope. In order to a deep understanding of neutron star, black hole, supernova scientist need X-ray telescope. They are not sensitive to pollution. The first x-ray telescope was launched by NASA named ‘Einstein’ later it was renamed as Chandra which sent an image from distant galaxies.