XMM-Newton Detection of X-Ray Emission from the Metal-polluted White Dwarf G 29-38

A recent analysis of Chandra X-ray data of the metal-polluted white dwarf G 29-38 has revealed X-ray emission that can be attributed to the accretion of debris from a planetary body. In the light of this detection we revisit here archival XMM-Newton observations of G 29-38 from which only an upper limit was derived in the past due to the presence of a relatively bright nearby X-ray source. An analysis of these data in multiple energy bands allows disentangling of the X-ray emission at the location of G 29-38 from that of the nearby source. The similar spectral properties of the source in the XMM-Newton and Chandra observations and their spatial shift, consistent with the proper motion of G 29-38 between these observations, strengthen the origin of the X-ray emission from G 29-38. The X-ray luminosities from both observations are consistent within the 1σ uncertainties, so too are the best-fit plasma temperatures. Although the count number is small, there is tantalizing evidence for line emission in the 0.7–0.8 keV energy band from an optically thin hot plasma. The most likely candidate for this line emission would be the Fe complex at 16 Å.