A Chandra observation of the z=2.285 galaxy FSC10214+4724: Evidence for a Compton-thick quasar?

We present a ~20 ks Chandra ACIS-S observation of the strongly lensed z=2.285 ultra-luminous infrared galaxy FSC10214+4724. Although this observation achieves the equivalent sensitivity of an up-to ~4 Ms Chandra exposure (when corrected for gravitational lensing), the rest-frame 1.6-26.3 keV emission from FSC10214+4724 is weak (L_X~2E42 erg/s for a lensing boost of ~100); a significant fraction of this X-ray emission appears to be due to vigorous star-formation activity. If FSC10214+4724 hosts a quasar, as previously suggested, then it must be obscured by Compton-thick material. We compare FSC10214+4724 to high-redshift SCUBA galaxies and discuss the X-ray identification of Compton-thick AGNs at high redshift.