ROSAT Hard-Spectrum X-Ray Source Catalog: 147 Serendipitous Sources

147 serendipitous X-ray sources with hard spectra (spectral indices Alpha < 0.5) were selected from a survey of 188 ROSAT fields. The catalog, created by NASA HEASARC in March 2012, suggests these hard sources are dominant contributors to the X-ray background at faint fluxes. Monte Carlo simulations indicate the survey's effective area for hard sources is >=10 times greater than for soft sources above a specific flux level.

Use Cases

• Modeling the X-ray background spectral paradox based on the population of hard sources.
• Analyzing the number-flux relation (dN/dS) for hard X-ray sources based on the reported Gamma value.
• Studying the spectral slope distribution of X-ray sources, where a typical source has Alpha ~ 0.
• Investigating the contribution of hard-spectrum sources to the total source count at specific flux ranges.

Strengths

• Contains 147 specifically selected hard-spectrum X-ray sources.
• Survey technique verified by Monte Carlo simulations for efficiency in selecting hard sources.
• Catalog provides a best-fitting value for the number-flux relation exponent (Gamma = 2.72 +/- 0.12).
• Estimates the hard source population's contribution (~15% to ~40%) at different flux levels.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.

Provenance

Source

NASA HEASARC, based on CDS Catalog J/MNRAS/318/1073.

Collection Method

Serendipitous source selection from a survey of 188 ROSAT fields.

Time Range

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Freshness

Last updated 2026-03-13 19:21:29.031622; freshness should be verified.

Geography

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