SIMBAD references

The pulsar birthrate (PB) in our galaxy is a parameter known with a large uncertainty. Different estimates indicate that 1/PB ranges between 30 and 250 years. Assuming a polar-cap model for gamma-ray production in gamma-ray pulsars, positron fraction measurements in cosmic rays above a few GeV make it possible to set a limit on PB. Recent measurements of the e⁺/(e⁺+e^–) ratio indicate a PB of one pulsar born every 200±100 years when the uncertainty on the secondary positron calculations is taken into account. A PB compatible with this result is found even in the case of a relevant production of positrons in the pulsar outer gaps.