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: http://www.sao.ru/Doc-en/SciNews/2011/Beskin/
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Detection of radio pulsar pairs -
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Russian version |
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According to modern views on the evolution and origin of stars,
most of the stars are members of binary systems. If both
components are massive enough, they eventually go supernova one by
one, whereas their cores collapse, turning into black holes or
neutron stars. After the second explosion, the pairs tend to break
up and neutron stars and/or black holes fly apart. High velocities
of radio pulsars are apparently largely due to this effect. Thus,
the kinematic characteristics of a pulsar (its position in the
alaxy, peculiar velocities) in combination with age carry the
data about its location at the time of birth. Comparing these
parameters in different pairs of sufficiently close objects, we
can find among them the companions that were part of broken binary
systems. To this end, we developed a method of analysis of the
kinematics of single radio pulsars, which have their proper
motions and distances measured. Using a standard distribution of
radial velocities for each object, we have computed from 100 to
300 thousand trajectories of its hypothetical movement in the
gravitational field of the Galaxy on the scale of a few million
years. For all possible pairs the probability of trajectory
approach at small distances for the epoch, corresponding to the
age of the younger pulsar have been evaluated. In the case when
these probabilities significantly exceed the reference values,
obtained in an assumption of a purely random approach of the
studied objects, it can be argued that they were part of a single
binary system. As a result, six pairs of pulsars were fond:
J0543+2329/J0528+2200, J1453-6413/J1430-6623,
J2354+6155/J2321+6024, J1915+1009/J1909+1102,
J1832-0827/J1836-1008, J1917+1353/J1926+1648, which were the
companions in broken up binary systems with a high probability.
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Fig.1. Pulsars J0543+2329 and J0528+2200. The projections of the spatial plane, where the measured minimal distance between the pulsars does not exceed ρ=10pc. Every dot on the diagram is a place of the the closest approach of pulsars for a given pair of trajectories. The circles mark the location of a younger pulsar at the current epoch, the diamonds - the location of an older pulsar. The lines are the trajectories at which the smallest computed distance between the pulsars ρmin is realized. The stars mark the region of its reach. Here ρmin=0.535pc. |