314 research outputs found
Cosmic-ray positron measurements: On the origin of the e+ excess and limits on magnetar birthrate
No full textPulsar birthrate set by cosmic-ray positron measurements
No full textThe 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
Possible consequences of a disk around B0656+14 on e+-e- and near-1 Hz gravitational wave production
No full textConstraints on cosmic-ray positron excess and average pulsar parameters
No full textRecent, accurate e+ /(e+ +e− ) ratio measurements in cosmic rays allow us to distinguish among different estimates of secondary positron production in the interstellar medium (ISM), provided the effect of solar modulation and solar polarity are properly taken into account. Data above a few GeV indicate that a possible extra component of positrons could be required in addition to the secondaries. This positron excess is compatible with the hypothesis of pair production at the polar cap of mature pulsars. Assuming only pulsar contributions without any exotic contributions such as dark-matter annihilation, the average parameters of Galactic pulsars contribut- ing to positron and electron interstellar fluxes were obtained. These parameter values are found near the peak of the distributions of the observed characteristics of radio pulsars. The studied gamma-ray pulsar sample is too small to make any conclusion. The expected e+ /(e+ +e− ) ratio from the PAMELA experiment currently in orbit is reported in this paper. The GLAST mission will allow us to double-check our findings about the role of pair production at the pulsar polar cap and outer gap
Insights from cosmic-ray positron measurements about young pulsar gravitational wave energy losses
No full textExperimental clues on pulsar energy losses and the role of circumpulsar supernova fallback disks
No full textPositron measurements in cosmic rays, studies of gravitational wave emission from isolated pulsars and observations of circumpulsar supernova fallback disks allow us to set upper limits on several energy loss mechanisms of young and mature pulsars. Presently, the above experimental evidences do not lead to conflicting scenarios. In particular, we focus on pulsar spin down due to friction or propeller torque from supernova fallback disks. Gravitational wave emission from circumpulsar planetary systems or precessing disks does not play a relevant role in pulsar spin down. However, the detection of gravitational waves from these systems with future space interferometers would allow us to estimate the fraction of pulsars surrounded by disks. While the planetary system detection appears to be unfeasible, the DECI-Hertz Interferometer Gravitational Wave Observatory (DECIGO) and the Big Bang Observatory (BBO) might reveal the presence of precessing disks
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