Q&A: X-ray Astronomy

Q:
What kind of polarization do X-rays have, linear or circular?

A:
X-rays, like other forms of electromagnetic radiation, can be unpolarized or have linear, circular or elliptical polarization, depending on the conditions under which they are produced. For example, polarized X-rays are expected from accretion disks around black holes, as well as from matter funneling onto the surface of a highly magnetized neutron star. Unfortunately, neither Chandra nor XMM-Newton has an X-ray polarimeter on board.