A study of 315 glitches in the rotation of 102 pulsars

Abstract: The rotation of more than 700 pulsars has been monitored using the 76-m Lovell Telescope at Jodrell Bank. Here we report on a new search for glitches in the observations, revealing 128 new glitches in the rotation of 63 pulsars. Combining these new data with those already published we present a database containing 315 glitches in 102 pulsars. The database was used to study the glitch activity among the pulsar population, finding that it peaks for pulsars with a characteristic age tau_c ~ 10kyr and decreases for longer values of tau_c, disappearing for objects with tau_c > 20Myr. The glitch activity is also smaller in the very young pulsars (tau_c <~ 1kyr). The cumulative effect of glitches, a collection of instantaneous spin up events, acts to reduce the regular long term spindown rate |nudot| of the star. The percentage of |nudot| reversed by glitch activity was found to vary between 0.5% and 1.6% for pulsars with spindown rates |nudot| between 10^-14 and 3.2*10^-11 Hz/s, decreasing to less than 0.01% at both higher and lower spindown rates. These ratios are interpreted in terms of the amount of superfluid involved in the generation of glitches. In this context the activity of the youngest pulsar studied, the Crab pulsar, may be explained by quake-like activity within the crust. Pulsars with low spindown rates seem to exhibit mostly small glitches, matching well the decrease of their crustal superfluid. Through the analysis of glitch sizes it was found that the particular glitching behaviour of PSR J0537-6910 and the Vela pulsar may be shared by most Vela-like pulsars. These objects present most of their glitches with characteristic frequency and frequency derivative jumps, occurring at regular intervals of time. Their behaviour is different from other glitching pulsars of similar characteristic age.

• The paper compiles 315 glitches across 102 pulsars and identifies 128 new events, providing a comprehensive dataset for analyzing pulsar spin irregularities.
• It correlates glitch activity with pulsar age and spindown rates, showing peak cumulative spin-up near a characteristic age of 10^4 years.
• The study interprets glitch behavior through superfluid dynamics, offering insights into the internal properties and evolutionary processes of neutron stars.

Insights into Pulsar Glitches: An Analysis of 315 Events

Pulsars, the highly magnetized, rotating neutron stars, offer a fascinating glimpse into the extreme physics of the universe. One of the intriguing aspects of their behavior is the occurrence of glitches—sudden changes in their rotation rate. The paper "A study of 315 glitches in the rotation of 102 pulsars," authored by Espinoza et al., presents a comprehensive analysis of pulsar glitches, making significant contributions to our understanding of these phenomena. It consolidates data on 315 glitches across 102 pulsars to investigate their characteristics and underlying mechanisms.

Glitch Detection and Database Construction

The authors utilized data from the Jodrell Bank Observatory, which has been monitoring over 700 pulsars using the 76-m Lovell Telescope. From this extensive dataset, they identify 128 new glitches, adding to the existing database. This robust compilation of 315 glitches covered a range of pulsars with varying ages and spin properties.

Characteristics of Glitch Events

A key finding is the frequency and magnitude distribution of glitches across the pulsar population. The glitch activity—quantified as the cumulative spin-up due to glitches—peaks for pulsars with characteristic ages around 10^4 years and declines for both younger and older pulsars. The study also finds a correlation between glitch activity and the pulsar spindown rate, indicating that this activity decreases as pulsars age or slow down.

The analyses reveal that the youngest pulsars, particularly those similar in age to the Crab pulsar (<1 kyr), exhibit lower glitch activity compared to slightly older pulsars such as Vela (~11 kyr). This suggests a potential dependence on internal temperature and crustal properties.

Implications of Glitch Behavior

The authors interpret the variation in glitch activity through the framework of superfluidity within the neutron star. The episodic transfer of angular momentum from superfluid interiors to the crust, a defining mechanism of glitches, implicates regions with pinning of superfluid vortices against the crustal lattice. This study underscores that the proportion of superfluid involved in glitches might decrease for pulsars with both extremely high and low spindown rates, potentially affecting the glitch magnitude and frequency.

Glitch Dynamics and Pulsar Evolution

Intriguingly, the paper highlights that while Vela-like pulsars tend to exhibit large, periodic glitches, other pulsars show a broad range of glitch sizes. This divergence suggests different internal mechanisms or evolutionary processes between pulsar subsets. For low-rate spindown pulsars exhibiting primarily small glitches, the glitch activity is negligible in affecting the long-term spin evolution, unlike in more energetic Vela-like pulsars.

Future Directions and Theoretical Implications

The detailed glitch database provides a foundation for refining models of neutron star interiors and their evolutionary paths. Understanding the extent to which superfluid dynamics contribute to pulsar glitches can illuminate processes at play in extreme astrophysical environments. Future research might focus on the microphysical conditions that differentiate Vela-like pulsar behavior from others.

Overall, the research by Espinoza et al. presents a rigorous analysis of pulsar glitches, enhancing the understanding of pulsar dynamics and neutron star interior physics. This work is instrumental in guiding both observational strategies and theoretical models that aim to explore and explain the nature of glitch events. The findings offer promising avenues for further exploration, potentially uncovering new aspects of pulsar evolution and the physics of dense matter.