Q&A: Galaxies, Galaxy Clusters, AGN, and Quasars

Q:
I know an X-ray record is different from a radio one, so what is in the left part of the radio registration that is absent in the Chandra´s quasar PKS 0637-72?

A:
Why the source to the left doesn't show up in X rays is not known. The most popular explanation is that the source on the right is part of a jet that is pointing toward us, and hence enhanced by the Doppler Effect, and the source on the left is pointing away from us, and hence diminished by the same effect.