Upper Limits on the High-Energy Gamma-Ray Fluxes from PSR:1951+32 and PSR:1509-58
Abstract
The high-energy gamma-ray telescope EGRET observed the positions of two young pulsars, PSR 1951 +32 and 1509- 58, during its all-sky survey. Despite their youth and relative proximity to the Earth, neither pulsar is detected as a point source or in periodicity analysis. Flux limits of a few × 10-7 photon cm-2 s-1 are obtained for emission above 100 MeV, and ∼10-6 photon cm-2 s-1 for 30-100 MeV. For the conventional assumption of beaming into 1 sr, the flux limits suggest that less than 3.2 per cent of the radiation from PSR 1509-58, and less than 1.8 per cent from PSR 1951+32, is in the form of beamed high-energy gamma-rays. The PSR 1509-58 limits lie approximately one order of magnitude below the extrapolated hard X-ray spectrum and suggest that the spectrum steepens in the MeV region.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 1994
- DOI:
- 10.1093/mnras/268.2.517
- Bibcode:
- 1994MNRAS.268..517B
- Keywords:
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- pulsars: individual: PSR 1509-58 - pulsars: individual: PSR 1951+32 - gamma-rays: observations