SEXSI Catalog: 1,034 Extragalactic Hard X-Ray Sources

The Serendipitous Extragalactic X-Ray Source Identification (SEXSI) catalog contains 1,034 hard X-ray (2-10 keV) sources identified from over 2 square degrees of Chandra observations. It was created by NASA HEASARC in 2004 based on published research, providing a sample at intermediate fluxes (~10^-13 to 10^-15 erg/cm^2/s) to complement deeper, narrower surveys.

Use Cases

• Modeling the log N - log S distribution of hard X-ray sources based on the cumulative flux data.
• Investigating the spectral properties of extragalactic sources based on hardness ratio distributions.
• Constraining the population of hard X-ray sources at intermediate flux levels where the number counts change slope.
• Comparing source characteristics between soft and hard sub-samples to infer redshift differences.

Strengths

• Contains 1,034 identified hard X-ray sources, providing a statistically significant sample.
• Covers over 2 square degrees of sky area, offering a broader spatial complement to deep field studies.
• Focuses on the intermediate flux range (~10^-13 to 10^-15 erg/cm^2/s) which contributes significantly to the X-ray background.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• The catalog does not include the Soft-Band-Only Source Catalog from the original paper.

Provenance

Source

National Aeronautics and Space Administration (NASA HEASARC)

Collection Method

Sources selected from Chandra ACIS observations at high Galactic latitude (|b| > 20 degrees) and accessible declinations (> -20 degrees).

Time Range

null

Freshness

Last updated 2026-03-13 18:27:10.879204; freshness should be verified.

Geography

High Galactic latitude sky fields, declination > -20 degrees.