A SPITZER SEARCH FOR INFRARED EXCESSES AROUND MASSIVE YOUNG WHITE DWARFS1

We examine 14 hot white dwarfs for signs of infrared excess using the Spitzer Space Telescope. Twelve of the objects are massive white dwarfs that have been suggested to be the result of binary mergers. The remaining two objects are undermassive white dwarfs that again may be the result of mergers, or of the in-spiral of a substellar companion. In no case do we find any evidence for significant infrared excesses out to wavelengths of 8 (mu)m. This places strong constraints on the presence of orbiting dust and weaker constraints on the presence of close substellar companions.