Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431

Arumugasamy, Prakash; Mitra, Dipanjan

doi:10.1093/mnras/stz2299

Cited by 31 publications

(23 citation statements)

References 93 publications

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“…Clearly, the blackbody fits which determine the radius of the real polar cap Rpc and Ts should be considered with caution. Due to the variance in the photon statistical data, both thermal and non-thermal X-ray spectra can be fitted equally well to various models (Arumugasamy & Mitra 2019). However, the availability of B d , Bs, R dip , Rpc, and Ts for a number of radio pulsars is reason enough, albeit with caution, given the large error bars at Ts, Rpc, and Bs, to study the establishment of the surface temperature of the real polar cap in greater detail.…”

Section: Introductionmentioning

confidence: 99%

Heating of the real polar cap of radio pulsars

Sznajder

Geppert

2020

Monthly Notices of the Royal Astronomical Society

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The heating of the real polar cap surface of radio pulsars by the bombardment of ultrarelativistic charges is studied. The real polar cap is a significantly smaller area within or close by the conventional polar cap which is encircled by the last open field lines of the dipolar field B d . It is surrounded by those field lines of the small scale local surface field B s that join the last open field lines of B d in a height of ∼ 10 5 cm above the cap. As the ratio of radii of the conventional and real polar cap R dip /R pc ∼ 10, flux conservation requires B s /B d ∼ 100. For rotational periods P ∼ 0.5 s, B s ∼ 10 14 G creates a strong electric potential gap that forms the inner accelerating region (IAR) in which charges gain kinetic energies ∼ 3 × 10 14 eV. This sets an upper limit for the energy that back flowing charges can release as heat in the surface layers of the real polar cap. Within the IAR, which is flown through with a dense stream of extremely energetic charges, no stable atmosphere of hydrogen can survive. Therefore, we consider the polar cap as a solidified "naked" surface consisting of fully ionized iron ions. We discuss the physical situation at the real polar cap, calculate its surface temperatures T s as functions of B s and P , and compare the results with X-ray observations of radio pulsars.

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Section: Introductionmentioning

confidence: 99%

Heating of the real polar cap of radio pulsars

Sznajder

Geppert

2020

Monthly Notices of the Royal Astronomical Society

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“…Several observational studies suggest that the IAR is dominated by strongly non-dipolar surface magnetic field (e.g. Arumugasamy & Mitra 2019) and as a consequence is not a pure vacuum gap as was initially assumed by Ruderman & Sutherland (1975), but form a PSG (Gil et al 2003) due to supply of thermally regulated ions from the stellar surface. The strong non-dipolar nature causes the field lines to become highly curved, thereby enhancing the generation and acceleration of the dense pair plasma in the PSG.…”

Section: The Properties Of Polar Cap Influencing Coherent Radio Emissionmentioning

confidence: 96%

Rapid Modification of Neutron Star Surface Magnetic Field: A proposed mechanism for explaining Radio Emission State Changes in Pulsars

Geppert,

Basu,

Mitra

et al. 2021

Preprint

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The radio emission in many pulsars show sudden changes, usually within a period, that cannot be related to the steady state processes within the inner acceleration region (IAR) above the polar cap. These changes are often quasi-periodic in nature, where regular transitions between two or more stable emission states are seen. The durations of these states show a wide variety ranging from several seconds to hours at a time. There are strong, small scale magnetic field structures and huge temperature gradients present at the polar cap surface. We have considered several processes that can cause temporal modifications of the local magnetic field structure and strength at the surface of the polar cap. Using different magnetic field strengths and scales, and also assuming realistic scales of the temperature gradients, the evolutionary timescales of different phenomena affecting the surface magnetic field was estimated. We find that the Hall drift results in faster changes in comparison to both Ohmic decay and thermoelectric effects. A mechanism based on the Partially Screened Gap (PSG) model of the IAR has been proposed, where the Hall and thermoelectric oscillations perturb the polar cap magnetic field to alter the sparking process in the PSG. This is likely to affect the observed radio emission resulting in the observed state changes.

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“…Third, the magnetic field evolution leaves its imprint on the timing evolution of NSs, either in the form of enhanced noise, or through their braking indices [91][92][93][94][95][96][97]. Fourth, the evolution of the magnetic field leads to the spontaneous formations of spots, arcades and multipolar structures [46,66,[98][99][100] which have been related to magnetars and have been directly observed in several NSs, either directly or as spectral features [101][102][103][104][105]. Fifth, apart from the obvious connection to strongly magnetised NSs, the Hall effect has been related to Central Compact Objects [106][107][108][109][110][111][112], in the scenario of the re-emergence of the buried magnetic field.…”

Section: Hall-ohmic Evolutionmentioning

confidence: 99%

Magnetic Field Evolution in Neutron Star Crusts: Beyond the Hall Effect

Gourgouliatos

Grandis²,

Igoshev

2022

Symmetry

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Neutron stars host the strongest magnetic fields that we know of in the Universe. Their magnetic fields are the main means of generating their radiation, either magnetospheric or through the crust. Moreover, the evolution of the magnetic field has been intimately related to explosive events of magnetars, which host strong magnetic fields, and their persistent thermal emission. The evolution of the magnetic field in the crusts of neutron stars has been described within the framework of the Hall effect and Ohmic dissipation. Yet, this description is limited by the fact that the Maxwell stresses exerted on the crusts of strongly magnetised neutron stars may lead to failure and temperature variations. In the former case, a failed crust does not completely fulfil the necessary conditions for the Hall effect. In the latter, the variations of temperature are strongly related to the magnetic field evolution. Finally, sharp gradients of the star’s temperature may activate battery terms and alter the magnetic field structure, especially in weakly magnetised neutron stars. In this review, we discuss the recent progress made on these effects. We argue that these phenomena are likely to provide novel insight into our understanding of neutron stars and their observable properties.

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Evaluating the evidence of multipolar surface magnetic field in PSR J0108–1431

Cited by 31 publications

References 93 publications

Heating of the real polar cap of radio pulsars

Heating of the real polar cap of radio pulsars

Rapid Modification of Neutron Star Surface Magnetic Field: A proposed mechanism for explaining Radio Emission State Changes in Pulsars

Magnetic Field Evolution in Neutron Star Crusts: Beyond the Hall Effect

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