Population synthesis of isolated neutron stars with magneto-rotational evolution

We revisit the population synthesis of isolated radio-pulsars incorporating recent advances on the evolution of the magnetic field and the angle between the magnetic and rotational axes from new simulations of the magneto-thermal evolution and magnetosphere models, respectively. An interesting novelty in our approach is that we do not assume the existence of a death line. We discuss regions in parameter space that are more consistent with the observational data. In particular, we find that any broad distribution of birth spin periods with P0 ≲ 0.5 s can fit the data, and that if the alignment angle is allowed to vary consistently with the torque model, realistic magnetospheric models are favoured compared to models with classical magneto-dipolar radiation losses. Assuming that the initial magnetic field is given by a lognormal distribution, our optimal model has mean strength 〈log B0[G]〉 ≈ 13.0–13.2 with width σ(log B0) = 0.6–0.7. However, there are strong correlations between parameters. This degeneracy in the parameter space can be broken by an independent estimate of the pulsar birth rate or by future studies correlating this information with the population in other observational bands (X-rays and γ-rays).

Is the date of birth an advantage/ally to excel in handball?

The Relative Age Effect (RAE) has been analyzed in a population of Spanish international handball players (n=161) divided into four different levels: Senior, Junior, Juvenile and Promising Talents. The variables registered were quarter, half year and year of birth using the initial information of their date of birth. The data were collected from the Royal Spanish Handball Federation on-line data base. The statistical method used was the χ2 and the minimum level of significance was set at p<0.05. The total results on distribution by quarter show a significant difference (χ2= 21.68; p<0.01) with a greater frequency of players born in the first quarter (40.37%) compared to those born in the second (22.36%), third (16.15%) and fourth quarter (21.12%). The total results on the distribution of birth date by half year show a significant difference (χ2= 10.44; p<0.01) with a greater frequency of players born in the first half of the year (62.73%). With regard to the rate of births registered in an even numbered or odd numbered year there are significant differences when the rates for an even numbered year (64.60%) and an odd numbered year (35.40%) are compared with those of the general population (χ2= 13.72; p<0.001). Based on the data collected and analyzed it can be concluded that there is a RAE in the basic categories of the Spanish national men’s handball teams according to quarter, half year and year of birth (even or odd numbered), but there exists little knowledge about the causes and consequence which may be produced by, or derive from, this effect.