We present point-source catalogs for the ≈2 Ms exposure of the Chandra Deep Field North, currently the deepest X-ray observation of the universe in the 0.5-8.0 keV band. Five hundred and three (503) X-ray sources are detected over an ≈448 arcmin2 area in up to seven X-ray bands. Twenty (20) of these X-ray sources lie in the central ≈5.3 arcmin2 Hubble Deep Field North (13,600-3000+3800 sources deg -2). The on-axis sensitivity limits are ≈2.5 × 10 -17 ergs cm-2 s-1 (0.5-2.0 keV) and ≈1.4 × 10-16 ergs cm-2 s-1 (2-8 keV). Source positions are determined using matched-filter and centroiding techniques; the median positional uncertainty is ≈0″.3. The X-ray colors of the detected sources indicate a broad variety of source types, although absorbed AGNs (including a small number of possible Compton-thick sources) are clearly the dominant type. We also match lower significance X-ray sources to optical counterparts and provide a list of 79 optically bright (R ≲ 23) lower significance Chandra sources. The majority of these sources appear to be starburst and normal galaxies. The average backgrounds in the 0.5-2.0 keV and 2-8 keV bands are 0.056 and 0.135 counts Ms-1 pixel-1, respectively. The background count distributions are very similar to Poisson distributions. We show that this ≈2 Ms exposure is approximately photon limited in all seven X-ray bands for regions close to the aim point, and we predict that exposures up to ≈25 Ms (0.5-2.0 keV) and ≈4 Ms (2-8 keV) should remain nearly photon limited. We demonstrate that this observation does not suffer from source confusion within ≈6′ of the aim point, and future observations are unlikely to be source-confusion limited within ≈3′ of the aim point even for source densities exceeding 100,000 deg-2. These analyses directly show that Chandra can achieve significantly higher sensitivities in an efficient, nearly photon-limited manner and be largely free of source confusion. To allow consistent comparisons, we have also produced point-source catalogs for the ≈1 Ms Chandra Deep Field South (CDF-S). Three hundred and twenty-six (326) X-ray sources are included in the main Chandra catalog, and an additional 42 optically bright X-ray sources are included in a lower significance Chandra catalog. We find good agreement with the photometry of the previously published CDF-S catalogs; however, we provide significantly improved positional accuracy.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science