Speaker
Description
The sudden increase in a pulsar's spin frequency,referred to as a pulsar glitch,offers valuable insights into the internal dynamics of neutron stars.These glitches occur from the rapid unpinning of superfluid vortices in the inner crust,resulting from a differential rotation lag between the crust and superfluid components.The size of these glitches is quantied as the fractional change (∆ν/ν).We calculated the fractional moment of inertia (FMI) and,for the first time,considered the number-of-rotations (NoR) that occur between glitches,allowing us to quantify the amount of superfluid that is coupled to the crust component.Using current glitch catalogs,we analyzed the distributions of ∆ν/ν,waiting-time ($t_g$),and NoR for 239 pulsars (706 glitches) as well as a subset of 49 pulsars (262 glitches),with further analyses focused on this subset due to its relevannce in the NoR calculation.The distribution of ∆ν/ν is bimodal, with two peaks representing small glitches (<$10^{−7}$) and large glitches (≥$10^{−7}$), suggesting the presence of dual glitch mechanisms. In contrast, the unimodal distributions observed in $t_g$ and NoR indicate that the factors influencing ∆ν/ν are not closely linked. Using Bayesian inference,we fitted linear models of FMI against ∆ν/ν,pulsar characteristic age (τ),and the healing parameter (Q). The results imply that superfluid dynamics play a crucial role in determining ∆ν/ν and Q, and that the amount of superfluid coupled to the crust moderately depends on τ,with older pulsars expected to have a higher FMI.We also modeled NoR against recovery time (T) and Q separately for the Crab and Vela pulsar. The moderate correlations obtained suggest the existence of a critical threshold in the coupled superfluid that governs ∆ν/ν. Lastly,model comparisons using widely applicable information criterion and leave-one-out cross-validation demonstrated that the linear relationship between ∆ν/ν and NoR is slightly better than the relationship between ∆ν/ν and $t_g$ in estimating the rotational lag between the superfluid and crust components.
| Stream | Science or Engineering |
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