Evidence for a 36 ks phase modulation in the hard X-ray pulses from the magnetar 1E 1547.0−5408

Makishima, Kazuo; Enoto, T.; Murakami, Hiroaki; Furuta, Yoshihiro; Nakano, T.; Sasano, M.; Nakazawa, K.

doi:10.1093/pasj/psv097

Cited by 23 publications

(16 citation statements)

References 42 publications

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“…The same pulse-phase modulation effects, as observed from 4U 0142+61, have also been discovered in Suzaku data of 1E 1547.0–4516, 68) the fastest-spinning ( P = 2.0721 sec) magnetar which became active in 2009 January (§ 4.3; orange in Fig. 7b).…”

Section: Challenging the Mysteries Of Magnetarssupporting

confidence: 77%

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X-ray studies of neutron stars and their magnetic fields

Makishima

2016

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

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Utilizing results obtained over the past quarter century mainly with Japanese X-ray astronomy satellites, a review is given to some aspects of neutron stars (NSs), with a particular emphasis on the magnetic fields (MFs) of mass-accreting NSs and magnetars. Measurements of electron cyclotron resonance features in binary X-ray pulsars, using the Ginga and Suzaku observatories, clarified that their surface MFs are concentrated in a narrow range of (1–7) × 108 T. Extensive studies of magnetars with Suzaku reinforced their nature as neutron stars with truly strong MFs, and revealed several important clues to their formation, evolution, and physical states. Taking all these results into account, a discussion is made on the origin and evolution of these strong MFs. One possible scenario is that the MF of NSs is a manifestation of some fundamental physics, e.g., neutron spin alignment or chirality violation, and the MF makes transitions from strong to weak states.

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Section: Challenging the Mysteries Of Magnetarssupporting

confidence: 77%

“… The 15–40 keV pulse profiles of the magnetar 1E 1547.0–4516, folded at a barycentric period of 2.07214 sec, in 6 different phases of the T = 36 ksec slip period. 68 ) Their average is shown in black at the middle. …”

Section: Figurementioning

confidence: 99%

X-ray studies of neutron stars and their magnetic fields

Makishima

2016

Proceedings of the Japan Academy. Ser. B: Physical and Biologic

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“…If the two conclusions are compatible, there should be a relation that B eff ∼ 0.01B t . This is consistent with the requirement in modeling AXPs/SGRs (Thompson & Duncan 1993, 1995 and the implication of the phase modulation observed for two magnetars (Makishima et al, 2014(Makishima et al, , 2016 that the internal toroidal fields of magetars can be up to 10 16 G.…”

Section: Two-case Studysupporting

confidence: 89%

Investigating magnetically-induced distortions of neutron stars through gamma-ray burst X-ray plateaus

Lin¹,

Du²,

Hou³

et al. 2021

Preprint

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Magnetic field may distort neutron stars (NSs), but the effect has not been robustly tested through gravitational-wave observation yet due to the absence of a fast rotating Galactic magnetar. The central objects of Gamma-ray bursts (GRBs) could be millisecond magnetars. Under the magnetar scenario on the X-ray plateaus of GRB afterglows, the spindown evolution modulated by the gravitational-wave radiation may be inferred from some special samples, so that the magnetically-induced distorting can be further estimated. According to two samples, GRB 060807 and GRB 070521, we found that the correlation between the effective ellipticity, ε B,eff , and effective dipole magnetic field strength on a neutron star (NS) surface, B eff , is ε B,eff ∼ 10 −4 ( B eff 10 14 G ) 2 . This result demands that B eff ∼ 0.01B t with B t being the internal toroidal magnetic field strength of NSs. We suggested that the torque generated during few unsymmetrical massive-star collapses may induce differential rotations in proto-NSs to amplify the internal toroidal fields.

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“…Similarly to our results, some observations suggest that the dipole may not be the strongest component of the magnetic field of magnetars. Indeed, Makishima et al (2016Makishima et al ( , 2019 have detected phase modulations in X-ray emissions from two magnetars, that are interpreted as a free precession due to prolate deformations of the neutron star under the torque of a very intense internal toroidal field. The MRI driven magnetic field is mainly toroidal and could be important to explain these observations.…”

Section: Discussionmentioning

confidence: 99%

A global model of the magnetorotational instability in protoneutron stars

Reboul-Salze,

Guilet,

Raynaud

et al. 2020

Preprint

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Context. Magnetars are isolated neutron stars characterized by their variable high-energy emission which is powered by the dissipation of enormous internal magnetic fields. The measured spin-down of magnetars constrains the magnetic dipole to be in the range of 10 14 to 10 15 G. The magnetorotational instability (MRI) is considered to be a promising mechanism to amplify the magnetic field in fastrotating protoneutron stars and form magnetars. This scenario is supported by many local studies which have shown that magnetic fields could be amplified by the MRI on small scales. However, the efficiency of the MRI at generating a dipole field is still unknown.Aims. To answer this question, we study the MRI dynamo in an idealized global model of a fast rotating protoneutron star with differential rotation. Methods. Using the pseudo-spectral code MagIC, we perform three-dimensional incompressible MHD simulations in spherical geometry with explicit diffusivities where the differential rotation is forced at the outer boundary. We performed a parameter study in which we varied the initial magnetic field and investigated different magnetic boundary conditions. These simulations were compared to local shearing box simulations performed with the code Snoopy. Results. We obtain a self-sustained turbulent MRI-driven dynamo, whose saturated state is independent of the initial magnetic field. The MRI generates a strong turbulent magnetic field of B ≥ 2 × 10 15 G and a non-dominant magnetic dipole, which represents systematically about 5% of the averaged magnetic field strength. Interestingly, this dipole is tilted towards the equatorial plane. By comparing these results with shearing box simulations, we find that local models can reproduce fairly well several characteristics of global MRI turbulence such as the kinetic and magnetic spectra. The turbulence is nonetheless more vigorous in the local models than in the global ones. Moreover, too large boxes allow for elongated structures to develop without any realistic curvature constraint, which may explain why these models tend to overestimate the field amplification. Conclusions. Overall, our results support the ability of the MRI to form magnetar-like large-scale magnetic fields. They furthermore predict the presence of a stronger small-scale magnetic field. The resulting magnetic field could be important to power outstanding stellar explosions, such as superluminous supernovae (SLSNe) and gamma-ray bursts (GRBs).

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Evidence for a 36 ks phase modulation in the hard X-ray pulses from the magnetar 1E 1547.0−5408

Cited by 23 publications

References 42 publications

X-ray studies of neutron stars and their magnetic fields

X-ray studies of neutron stars and their magnetic fields

Investigating magnetically-induced distortions of neutron stars through gamma-ray burst X-ray plateaus

A global model of the magnetorotational instability in protoneutron stars

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