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| Paper: |
Hard X-ray and Infrared Emission from Apparently Single White Dwarfs |
| Volume: |
372, 15th European Workshop on White Dwarfs |
| Page: |
337 |
| Authors: |
Chu, Y.-H.; Gruendl, R.A.; Guerrero, M.A.; Su, K.Y.-L. |
| Abstract: |
The photospheric emission of a white dwarf (WD) is not expected to be detectable in hard X-rays or the mid-IR. Hard X-ray (~1 keV) emission associated with a WD is usually attributed to a binary companion; however, emission at 1 keV has been detected from three WDs without companions: KPD 0005+5106, PG 1159−035, and WD 2226−210. The origin of their hard X-ray emission is unknown, although it has been suggested that WD2226−210 has a late-type companion whose coronal activity is responsible for the hard X-rays. Recent Spitzer observations of WD2226−210 revealed mid-IR excess emission indicative of the existence of a dust disk. It now becomes much less clear whether WD2226−210's hard X-ray emission originates from the corona of a late-type companion or from the accretion of the disk material. High-quality X-ray observations and mid-IR observations of KPD0005+5106 and PG1159 are needed to help us understand the origin of their hard X-ray emission. |
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