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Glitch rises as a test for rapid superfluid coupling in neutron stars

Glitch rises as a test for rapid superfluid coupling in neutron stars
Glitch rises as a test for rapid superfluid coupling in neutron stars
Pulsar glitches provide a unique way to study neutron star microphysics because short post-glitch dynamics are directly linked to strong frictional processes on small scales. To illustrate this connection between macroscopic observables and microphysics, we review calculations of vortex interactions focusing on Kelvin wave excitations and determine the corresponding mutual friction strength for realistic microscopic parameters in the inner crust. These density-dependent crustal coupling profiles are combined with a simplified treatment of the core coupling and implemented in a three-component neutron star model to construct a predictive framework for glitch rises. As a result of the density-dependent dynamics, we find the superfluid to transfer angular momentum to different parts of the crust and the core on different timescales. This can cause the spin frequency change to become non-monotonic in time, allowing for a maximum value much larger than the measured glitch size, as well as a delay in the recovery. The exact shape of the calculated glitch rise is strongly dependent on the relative strength between the crust and core mutual friction, providing the means to probe not only the crustal superfluid but also the deeper neutron star interior. To demonstrate the potential of this approach, we compare our predictive model with the first pulse-to-pulse observations recorded during the December 2016 glitch of the Vela pulsar. Our analysis suggests that the glitch rise behavior is relatively insensitive to the crustal mutual friction strength as long as $\mathcal{B} \gtrsim 10^{-3}$, while being strongly dependent on the core coupling strength, which we find to be in the range $3 \times 10^{-5} \lesssim \mathcal{B}_{\rm core} \lesssim 10^{-4}$.
0004-637X
Graber, Vanessa
dcdc6f13-c329-46ee-829e-a03fab87187b
Cumming, A.
533b7dad-e34c-492f-a284-5b69a9c362be
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304
Graber, Vanessa
dcdc6f13-c329-46ee-829e-a03fab87187b
Cumming, A.
533b7dad-e34c-492f-a284-5b69a9c362be
Andersson, Nils
2dd6d1ee-cefd-478a-b1ac-e6feedafe304

Graber, Vanessa, Cumming, A. and Andersson, Nils (2018) Glitch rises as a test for rapid superfluid coupling in neutron stars. The Astrophysical Journal. (doi:10.3847/1538-4357/aad776).

Record type: Article

Abstract

Pulsar glitches provide a unique way to study neutron star microphysics because short post-glitch dynamics are directly linked to strong frictional processes on small scales. To illustrate this connection between macroscopic observables and microphysics, we review calculations of vortex interactions focusing on Kelvin wave excitations and determine the corresponding mutual friction strength for realistic microscopic parameters in the inner crust. These density-dependent crustal coupling profiles are combined with a simplified treatment of the core coupling and implemented in a three-component neutron star model to construct a predictive framework for glitch rises. As a result of the density-dependent dynamics, we find the superfluid to transfer angular momentum to different parts of the crust and the core on different timescales. This can cause the spin frequency change to become non-monotonic in time, allowing for a maximum value much larger than the measured glitch size, as well as a delay in the recovery. The exact shape of the calculated glitch rise is strongly dependent on the relative strength between the crust and core mutual friction, providing the means to probe not only the crustal superfluid but also the deeper neutron star interior. To demonstrate the potential of this approach, we compare our predictive model with the first pulse-to-pulse observations recorded during the December 2016 glitch of the Vela pulsar. Our analysis suggests that the glitch rise behavior is relatively insensitive to the crustal mutual friction strength as long as $\mathcal{B} \gtrsim 10^{-3}$, while being strongly dependent on the core coupling strength, which we find to be in the range $3 \times 10^{-5} \lesssim \mathcal{B}_{\rm core} \lesssim 10^{-4}$.

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Accepted/In Press date: 27 July 2018
e-pub ahead of print date: 18 September 2018

Identifiers

Local EPrints ID: 424211
URI: http://eprints.soton.ac.uk/id/eprint/424211
ISSN: 0004-637X
PURE UUID: aa740cbb-6558-4ecd-a288-97a15d5331d1
ORCID for Nils Andersson: ORCID iD orcid.org/0000-0001-8550-3843

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Date deposited: 05 Oct 2018 11:34
Last modified: 17 Dec 2019 05:13

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