Detection of X-Ray Emission from Gravitationally Lensed Submillimeter Sources in the Field of Abell 370

We report the detection by Chandra of SMM J02399-0134 and SMM J02399-0136,two distant (z=1.06 and z=2.81, respectively) submillimeter sourcesgravitationally magnified by the galaxy cluster Abell 370. These arehigh-significance (> 7-sigma) X-ray detections of the high-redshiftsubmillimeter source population. The X-ray positions are coincident with theoptical positions to within one arcsecond. The X-ray spectra, while of lowsignal-to-noise ratio, are quite hard. Absorbed power law models with fixedphoton indices of $\Gamma=2.0$ imply local absorbing columns $>2 \times10^{23}$ cm$^{-2}$ and unabsorbed luminosities $>10^{44}$ erg s$^{-1}$ in bothsources. These results imply that nuclear activity is responsible for the bulkof the luminosity in SMM J02399-0134, and for at least 20% of the luminosity ofSMM J02399-0136, consistent with previous optical observations. We also placean upper limit on the X-ray flux of a third submillimeter source, SMMJ02400-0134. Considered together with previously published Chandra upper limitson X-ray flux from submillimeter sources, our results imply that$20^{+30}_{-16}$ % of submillimeter sources exhibit X-ray emission from AGN(90% confidence), consistent with expectations of their contribution to thediffuse X-ray background.Comment: Corrected typos in Figure 1 labels; Accepted for publication in ApJ Letters, 6 pages, 2 figures, latex requires emulateapj5.st