Velocities and ages of neutron stars

TYPEAstrophysics Seminar
Speaker:Andrei Igoshev
Location:Lidow 620

Knowledge of the velocity distribution of neutron stars is essential for our understanding of neutron star ages, the rate of the double neutron stars mergers and the supernova explosion physics. Binaries with a neutron star which receive low natal kick stay bound more frequently after a supernova explosion. We have investigated the most precise parallaxes and proper motions of isolated pulsars (only interferometric measurements) and recycled radio pulsars (timing measurements) through the maximum likelihood technique. We have found that both these groups show a very broad velocity distribution, which we describe with a sum of two Maxwellians. 42% of young neutron stars are drawn from a Maxwellian with σ=77 km/s, and the remainder from a Maxwellian with σ=320 km/s. 66% of the recycled neutron stars have σ=38 km/s and remaining part has σ=150 km/s. We argue that the low and high velocities in the natal kick distribution are caused by different supernova explosion mechanisms. Neutron stars in millisecond binaries with higher speeds tend to be more massive than those in slower binaries. This updated velocity distribution is used to estimate the kinematic ages of young isolated radio pulsars and in particular to study the origin of excessive heat of B0950+08.