X‐Ray Sources in the Hubble Deep Field Detected byChandra

We present first results from an X-ray study of the Hubble Deep Field North(HDF-N) and its environs obtained using 166 ks of data collected by theAdvanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-rayObservatory. This is the deepest X-ray observation ever reported, and in theHDF-N itself we detect six X-ray sources down to a 0.5--8 keV flux limit of4E-16 erg cm^-2 s^-1. Comparing these sources with objects seen inmultiwavelength HDF-N studies shows positional coincidences with the extremelyred object NICMOS J123651.74 +621221.4, an active galactic nucleus (AGN), threeelliptical galaxies, and one nearby spiral galaxy. The X-ray emission from theellipticals is consistent with that expected from a hot interstellar medium,and the spiral galaxy emission may arise from a `super-Eddington' X-ray binaryor ultraluminous supernova remnant. Four of the X-ray sources have beendetected at radio wavelengths. We also place X-ray upper limits on AGNcandidates found in the HDF-N, and we present the tightest constraints yet onX-ray emission from the SCUBA submillimeter source population. None of the 10high-significance submillimeter sources reported in the HDF-N and its vicinityis detected with Chandra ACIS. These sources appear to be dominated by starformation or have AGN with Compton-thick tori and little circumnuclear X-rayscattering.