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Pulsar Drum: Three Glitches in the Rhythm ✛

Original: "Discovery of Three Glitches in the previously quiet pulsar PSR J1637$$-$$4642"
· Zhaoyi Wang, Chuwen Zheng, Yuhong Zhuang, Hanyu Zhang, Peng Liu, Zhonghao Tu, Ang Li
arXiv:2608.19555v1 · 2026-08-20 · CC BY 4.0 · 1 min
High Energy Stellar Nuclear Theory
A pulsar that spun steadily for decades suddenly sped up three times, and that helped peer inside the star.

A pulsar is a lighthouse star: it spins rapidly and emits radio pulses like a beam. Pulsar PSR J1637−4642 spun steadily for nine and a half years, but then its rhythm faltered three times. The strongest glitch, a sudden acceleration, boosted the spin by 2.7 parts per million. That's like the second hand of a clock suddenly speeding up by one ten-billionth of a second per year.

A glitch is a sudden speed-up in a pulsar's rotation. Inside the star, a superfluid (a frictionless liquid) rotates separately from the crust, and when it breaks free, it transfers its angular momentum to the crust.

After the first jump, the star began to settle back toward its old rhythm, but only a small fraction—1.5% of the jump — recovered over about 100 days. This helped calculate that about 1.9% of the star's mass is superfluid. Previously, no such glitches had been seen in this pulsar, and astronomers thought it was "quiet." Now it's clear: it was building up stress like a spring, and then letting go. This knowledge has no engineering applications, but it helps us understand how neutron stars are built.

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The weakest glitch of this pulsar changed its rotation frequency by just 14 nanohertz — equivalent to a clock's second hand speeding up by one ten-billionth of a second per year.

\phi(t) = \phi_0 + \nu(t-t_0) + \frac{\dot{\nu}}{2}(t-t_0)^2 + \frac{\ddot{\nu}}{6}(t-t_0)^3
Taylor expansion of the pulsar's rotation phase up to the third term
\phi_g = \Delta\phi + \Delta\nu_p (t-t_g) + \frac{1}{2}\Delta\dot{\nu}_p (t-t_g)^2 + \sum_i \Delta\nu_d^i \tau_d^i \left[1 - e^{-(t-t_g)/\tau_d^i}\right]
Phenomenological glitch model: permanent jumps in frequency and its derivative plus exponential decays
\dot{\nu}_c(t) = -\frac{I_l}{I}\frac{\delta\omega e^{-t/\tau}}{\tau} + \dot{\nu}_0 + \ddot{\nu} t
The rate of change of the crust's frequency is the sum of an exponentially decaying response from the superfluid component and a linear trend
Scientists
Albert EinsteinBarry BarishKip ThorneRichard FeynmanRussell HulseJocelyn Bell Burnell
Concepts
pulsar glitch magnetar glitch