Magnetic field growth in young glitching pulsars with a braking index
Magnetic field growth in young glitching pulsars with a braking index
In the standard scenario for spin evolution of isolated neutron stars, a young pulsar slows down with a surface magnetic field B that does not change. Thus the pulsar follows a constant B trajectory in the phase space of spin period and spin period time derivative. Such an evolution predicts a braking index n = 3 while the field is constant and n > 3 when the field decays. This contrasts with all nine observed values being n < 3. Here we consider a magnetic field that is buried soon after birth and diffuses to the surface. We use a model of a growing surface magnetic field to fit observations of the three pulsars with lowest n: PSR J0537-6910 with n = -1.5, PSR B0833-45 (Vela) with n = 1.4, and PSR J1734-3333 with n = 0.9. By matching the age of each pulsar, we determine their magnetic field and spin period at birth and confirm the magnetar-strength field of PSR J1734-3333. Our results indicate that all three pulsars formed in a similar way to central compact objects (CCOs), with differences due to the amount of accreted mass. We suggest that magnetic field emergence may play a role in the distinctive glitch behaviour of low braking index pulsars, and we propose glitch behaviour and characteristic age as possible criteria in searches for CCO descendants.
845-851
Ho, Wynn C.G.
d78d4c52-8f92-4846-876f-e04a8f803a45
8 July 2015
Ho, Wynn C.G.
d78d4c52-8f92-4846-876f-e04a8f803a45
Ho, Wynn C.G.
(2015)
Magnetic field growth in young glitching pulsars with a braking index.
Monthly Notices of the Royal Astronomical Society, 452 (1), .
(doi:10.1093/mnras/stv1339).
Abstract
In the standard scenario for spin evolution of isolated neutron stars, a young pulsar slows down with a surface magnetic field B that does not change. Thus the pulsar follows a constant B trajectory in the phase space of spin period and spin period time derivative. Such an evolution predicts a braking index n = 3 while the field is constant and n > 3 when the field decays. This contrasts with all nine observed values being n < 3. Here we consider a magnetic field that is buried soon after birth and diffuses to the surface. We use a model of a growing surface magnetic field to fit observations of the three pulsars with lowest n: PSR J0537-6910 with n = -1.5, PSR B0833-45 (Vela) with n = 1.4, and PSR J1734-3333 with n = 0.9. By matching the age of each pulsar, we determine their magnetic field and spin period at birth and confirm the magnetar-strength field of PSR J1734-3333. Our results indicate that all three pulsars formed in a similar way to central compact objects (CCOs), with differences due to the amount of accreted mass. We suggest that magnetic field emergence may play a role in the distinctive glitch behaviour of low braking index pulsars, and we propose glitch behaviour and characteristic age as possible criteria in searches for CCO descendants.
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Published date: 8 July 2015
Organisations:
Applied Mathematics
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Local EPrints ID: 377979
URI: http://eprints.soton.ac.uk/id/eprint/377979
ISSN: 1365-2966
PURE UUID: c0380431-1819-4644-bcca-60b7025f3a9c
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Date deposited: 25 Jun 2015 13:43
Last modified: 14 Mar 2024 20:13
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