First results from XMM-Newton observations of the Canada France Redshift Survey ( CFRS ) 3hr , 10hr and 14hr fields are presented .
Limited regions of two of the XMM surveys ( 3 and 14hr ) are compared to the Canada UK Deep sub-mm Surveys ( CUDSS ) undertaken with SCUBA .
None of the 27 SCUBA sources in the 3hr field are detected by XMM , while one of the 23 SCUBA sources in the 14hr field is found to coincide with an X-ray source .
The SCUBA population as a whole is not significantly detected in either the 0.5 - 2 ~ { } keV or the 2 - 10 ~ { } keV X-ray bands , even after coadding the X-ray flux at the SCUBA positions , in both fields .
The 18 X-ray sources within the CUDSS 3hr map yield a mean sub-mm flux of 0.48 \pm 0.27 ~ { } mJy after coadding the sub-mm flux at the X-ray positions .
Using this result we place an upper limit on the contribution of AGN to the sub-mm background at 850 ~ { } \mu m of \sim 7 ~ { } per~ { } cent .
Conversely we estimate the contribution of sub-mm sources to the 0.5 - 2 ~ { } keV X-ray background to be < 16.5 ~ { } per~ { } cent .
These results strongly support the conclusion that the two backgrounds are caused by different processes , in the one case nucleosynthesis in stars , in the other accretion onto black-holes .
We conclude that it is possible for SCUBA sources in general to contain AGN , as long as they are Compton-thick and are at z > 2.3 .
The ratio of the X-ray to sub-mm flux for the X-ray sources however , implies that even when a galaxy does contain an AGN , most of the energy heating the dust is from young stars and not from the active nucleus .