Large polar caps for twisted magnetosphere of magnetars

Tong, H.

doi:10.1093/mnras/stz2438

Cited by 10 publications

(17 citation statements)

References 43 publications

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“…Magnetars may have a twisted magnetic field compared with that of normal pulsars (Thompson et al 2002;Beloborodov 2009;Pavan et al 2009). A twisted magnetic field will result in a larger polar cap (Tong 2019). This will also result in a larger potential drop across the polar cap.…”

Section: Modification Of Pulsar Death Line For Long-period Radio Pulsarsmentioning

confidence: 99%

“…For a twisted dipole field, the radial dependence of the magnetic field is B(r) ∝ r −(2+ n) (Wolfson 1995), where n = 1 corresponds to the dipole case, n = 0 corresponds to the split monopole case, and 0 < n < 1 corresponds to a twisted dipole case. Due to inflation of the field line in the radial direction of a twisted dipole field, more field lines will become open, and a larger polar cap will be expected (Tong 2019). According to Equation (12) in Tong (2019), the polar cap for a twisted dipole field is…”

Section: Modification Of Pulsar Death Line For Long-period Radio Pulsarsmentioning

confidence: 99%

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Discussions on the Nature of GLEAM-X J162759.5–523504.3

Tong

2023

ApJ

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The nature of the long-period radio transient GLEAM-X J162759.5−523504.3 (hereafter GLEAM-X J1627) is discussed. We try to understand both its radio emission and pulsation in the neutron star scenario as an alternative to the white dwarf model. We think that (1) from the radio emission point of view, GLEAM-X J1627 can be a radio-loud magnetar; (2) from the rotational evolution point of view, GLEAM-X J1627 is unlikely to be an isolated magnetar; (3) the 1091 s period is unlikely to be the precession period; (4) GLEAM-X J1627 may be a radio-loud magnetar spun down by a fallback disk; (5) the pulsar death line is modified due to the presence of a fallback disk or a twisted magnetic field. In both cases, a higher maximum acceleration potential can be obtained. This may explain why GLEAM-X J1627 is still radioactive with such a long pulsation period; and (6) general constraints on the neutron star magnetic field and initial disk mass are given analytically. Possible ways to discriminate between different modelings are also discussed.

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Section: Modification Of Pulsar Death Line For Long-period Radio Pulsarsmentioning

confidence: 99%

Section: Modification Of Pulsar Death Line For Long-period Radio Pulsarsmentioning

confidence: 99%

Discussions on the Nature of GLEAM-X J162759.5–523504.3

Tong

2023

ApJ

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“…The effect of rotation (Blaskiewicz et al 1991;Wang et al 2012) and polar cap currents (Hibschman & Arons 2001) will result in modifications to RVM. In the case of magnetars, the magnetic field may be a twisted dipolar (Thompson et al 2002;Tong 2019). Then the RVM for magnetars will also change to some degree (Tong et al 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Both works suggest the presence of a multipolar field near the pulsar's surface. In the existence of multipole magnetic fields in pulsars and magnetars (Thompson et al 2002;Beloborodov 2009;Pavan et al 2009;Bilous et al 2019;Tong 2019), the RVM may also change.…”

Section: Introductionmentioning

confidence: 99%

Rotating Vector Model and Radius-to-frequency Mapping in the Presence of a Multipole Magnetic Field

Qiu,

Tong,

Wang

2023

ApJ

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The rotating vector model and radius-to-frequency mapping in the presence of a multipole magnetic field in pulsars and magnetars are considered. An axisymmetric potential field is assumed, and the following is found: (1) The radiation beam in the case of a multipole field is wider than the dipole case. This may account for the increasing pulse width at the higher frequency of pulsars (anti-radius-to-frequency mapping); (2) The expression for the polarization position angle is unchanged. Only the inclination angle α and phase constant ϕ 0 will change. The angle between the rotational axis and line of sight and the position angle constant ψ 0 will not change. When fitting the varying position angle of magnetars, these constraints should be considered. The appearance and disappearance of a multipole field may account for the changing slope of the position angle in the radio-emitting magnetar Swift J1818.0–1607. A similar but more active process in magnetar magnetospheres may account for the diverse position angle in fast radio bursts.

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“…The present model cannot be modified for the case of an oblique rotator as the computational code does not take into account the time evolution of the system. There is great freedom on the relation between I and Ψ, the one we follow comes from the relationship (Viganò 2013;Tong 2019):…”

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confidence: 99%

Force-free and twisted, relativistic neutron star magnetosphere

Ntotsikas

Gourgouliatos

2020

Proc. IAU

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In this poster we present the structure of an axisymmetric, force-free magnetosphere of a twisted, aligned rotating dipole within a corotating plasma-filled magnetosphere. We explore various profiles for the twist. We find that as the current increases more field lines cross the light cylinder leading to more efficient spin-down. Moreover, we notice that the twist cannot be increased indefinitely and after a finite twist of about π/2 the field becomes approximately radial. This could have implications for torque variations of magnetars related to outbursts.

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Large polar caps for twisted magnetosphere of magnetars

Cited by 10 publications

References 43 publications

Discussions on the Nature of GLEAM-X J162759.5–523504.3

Discussions on the Nature of GLEAM-X J162759.5–523504.3

Rotating Vector Model and Radius-to-frequency Mapping in the Presence of a Multipole Magnetic Field

Force-free and twisted, relativistic neutron star magnetosphere

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