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Astron. Astrophys. 350, 847-851 (1999)

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New observational constraints on hard X-/[FORMULA]-ray millisecond pulsar emission from 47 Tucanae

C. Ferguson, F. Lei, A.J. Dean, A.J. Bird and J.J. Lockley

Department of Physics and Astronomy, University of Southampton, UK (cf@astro.soton.ac.uk)

Received 10 June 1999 / Accepted 30 August 1999


Recent X-/[FORMULA]-ray observations with the Rossi X-ray Timing Explorer (RXTE) of 47 Tuc (NGC 104) are used to compare different models of millisecond pulsar emission. Data from both the Proportional Counter Array and the High Energy X-ray Timing Experiment are presented, covering a total energy range of 2-250 keV.

A new upper limit on the hard X-/[FORMULA]-ray emission from 47 Tuc is set, suggesting that the isolated millisecond pulsars may be non-emitting or very weak X-ray sources. The current binary X-ray emission theory is consistent with this result with some modification.

Timing analysis reveals no periodic pulsations in the data, further suggesting that isolated millisecond pulsars are very weak X-ray emitters.

Key words: X-rays: stars – stars: binaries: general – stars: pulsars: general – Galaxy: globular clusters: individual: 47 Tuc

Send offprint requests to: C. Ferguson

© European Southern Observatory (ESO) 1999

Online publication: October 14, 1999