A limit on the number of isolated neutron stars detected in the ROSAT Bright Source Catalogue

Roberte E. Rutledge, Derek W. Fox, Milan Bogosavljevic, Ashish Mahabal

Research output: Contribution to journalArticle


The challenge in searching for non-radio-pulsing isolated neutron stars (INSs) is in excluding association with objects in the very large error boxes (∼13″, 1 σ radius) typical of sources from the largest X-ray all-sky survey, the ROSA T All-Sky Survey Bright Source Catalogue (RASS BSC). We search for candidate INSs using statistical analysis of optical (USNO-A2), infrared (IRAS), and radio (NVSS) sources near the ROSAT X-ray localization and show that this selection would find 20% of the INSs in the RASS BSC. This selection finds 32 candidates at declinations δ > -39°, among which are two previously known INSs, 17 sources that we show are not INSs, and 13 the classification of which are as yet undetermined. These results require a limit of less than 67 INSs (90% confidence, full sky, assuming isotropy) in the RASS BSC. This limit modestly constrains a naive and optimistic model for cooling neutron stars in the Galaxy.

Original languageEnglish (US)
Pages (from-to)458-473
Number of pages16
JournalAstrophysical Journal
Issue number1 I
Publication statusPublished - Nov 20 2003



  • Stars: neutron
  • X-rays: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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