Energy transformations in the birth of neutron stars

24 Mar 2014, 18:00
15m

Speaker

Dr Ricardo Heras (University College London)

Description

Millisecond pulsars, radio pulsars, and magnetars are distinct classes of neutron stars that currently exhibit different periods, magnetic fields and space velocities. In my talk, I speculate with the idea that these current properties of neutron stars could have had similar values during the birth of these stars. I develop a relatively simple model based on the assumption that neutron stars experienced three abrupt physical changes at the end of their birth, which could have been originated in birth magneto-rotational instabilities: an increase in period from the initial value to the current value, implying a change of rotational energy; an exponential decay of its magnetic field from the initial value to the current surface value, implying a change of radiative energy; and finally, an increase of space velocity from the initial value to the current value, implying a change of kinetic energy. These birth energy changes are assumed to be connected by an energy conversion in which a radiation loss and an increase of kinetic energy occur at the expense of a rotational energy loss. According to this model, If the assumed energy conversion occurs in times of order 10^(-4) s then neutron stars are born with magnetic fields in the range of 10^(15)-10^(16) G and initial periods in range 1-20 ms. This means that neutron stars are born with magnetic fields typical of magnetars and periods typical of millisecond pulsars.

Primary author

Dr Ricardo Heras (University College London)

Presentation materials