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1st of May 2020
Pulsar braking indices
by Parthasarathy et al.
The long-term spin-down of a pulsar can be approximated by relating its frequency derivative to the rotational frequency raised to the power n, where n is referred to as the braking index. The braking index describes the relationship between the braking torque acting on a pulsar and its spin-frequency parameters, and provides a probe into the physics determining pulsar temporal evolution.

Parthasarathy et al. have used ~10 years of timing observations from the Parkes radio-telescope to measure the braking index for 19 pulsars and demonstrate that the value of n can be significantly larger than the canonical value of 3. The figure above shows the characteristic age versus braking index for 17 pulsars discussed in the paper (red circles) along with seven non-detections of n with strongly constrained limits (blue circles). The moderate correlation of braking index with characteristic age evident in the figure may be attributable to either magnetic field decay and/or changes in the pulsar's inclination angle. The possible implications of this finding are discussed the paper, published in Monthly Notices of the Royal Astronomical Society.

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