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Ultraluminous X-Ray Sources in Nearby Galaxies Catalog

Metadata Updated: April 10, 2026

One hundred and seven ultraluminous X-ray sources (ULXs) with 0.3-10.0 keV luminosities in excess of 10<sup>39</sup> erg s<sup>-1</sup> are identified in a complete sample of 127 nearby galaxies. The sample includes all galaxies within 14.5 Mpc above the completeness limits of both the Uppsala Galaxy Catalogue and the Infrared Astronomical Satellite survey. The galaxy sample spans all Hubble types, a four-decade range in mass, 7.5 < log (M/M<sub>sun</sub>) < 11.4, and in star formation rate, 0.0002 < SFR(M<sub>sun</sub> yr<sup>-1</sup>) <= 3.6. ULXs are detected in this sample at rates of one per 3.2 x 10<sup>10</sup> M<sub>sun</sub>, one per ~0.5 M<sub>sun</sub> yr<sup>-1</sup> star formation rate, and one per 57 Mpc<sup>3</sup> corresponding to a luminosity density of ~2 x 10<sup>37</sup> erg s<sup>-1</sup> Mpc<sup>-3</sup>. At these rates, the authors estimate as many as 19 additional ULXs remain undetected in fainter dwarf galaxies within the survey volume. An estimated 14 objects, or 13%, of the 107 ULX candidates are expected to be background sources. The differential ULX luminosity function shows a power-law slope alpha ~ -0.8 to -2.0 with an exponential cutoff at ~20 x 10<sup>39</sup> erg s<sup>-1</sup> with precise values depending on the model and on whether the ULX luminosities are estimated from their observed numbers of counts or, for a subset of candidates, from their spectral shapes. Extrapolating the observed luminosity function predicts at most one very luminous ULX, L<sub>X</sub> ~ 10<sup>41</sup> erg s<sup>-1</sup>, within a distance as small as 100 Mpc. The luminosity distribution of ULXs within the local universe cannot account for the recent claims of luminosities in excess of 2 x 10<sup>41</sup> erg s<sup>-1</sup>, requiring a new population class to explain these extreme objects. This table was created by the HEASARC in November 2011 based on an electronic version of Table 1 from the reference paper that was obtained from the ApJ web site. This is a service provided by NASA HEASARC .

Access & Use Information

Public: This dataset is intended for public access and use. License: See this page for license information.

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Dates

Metadata Created Date April 11, 2025
Metadata Updated Date April 10, 2026

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date April 11, 2025
Metadata Updated Date April 10, 2026
Publisher High Energy Astrophysics Science Archive Research Center
Maintainer
Identifier ivo://nasa.heasarc/ulxngcat
Data Last Modified 2026-04-06
Category Astrophysics
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Harvest Object Id 484a1fb6-1f8d-4563-920a-417f9dc5bab1
Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
Harvest Source Title NASA Data.json
Homepage URL ivo://nasa.heasarc/ulxngcat
License https://www.usa.gov/government-works
Program Code 026:000
Source Datajson Identifier True
Source Hash 22ca7fa6d3d7bcc417251197dad8774a35ccabd805f2a27cf089c7e7d62ec519
Source Schema Version 1.1

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