分类： 物理学 >> 核物理学 提交时间： 2016-09-14
摘要： We study the possibility that the long term red timing-noise in pulsars originates from the evolution of the magnetic inclination angle χ. The braking torque under consideration is a combination of the dipole radiation and the current loss. We find that the evolution of χ can give rise to extra cubic and fourth-order polynomial terms in the timing residuals. These two terms are determined by the efficiency of the dipole radiation, the relative electric-current density in the pulsar tube and χ. The following observation facts can be explained with this model: a) young pulsars have positive ν¨; b) old pulsars can have both positive and negative ν¨; c) the absolute values of ν¨ are proportional to −ν˙; d) the absolute values of the braking indices are proportional to the characteristic ages of pulsars. If the evolution of χ is purely due to rotation kinematics, then it can not explain the pulsars with braking index less than 3, and thus the intrinsic change of the magnetic field is needed in this case. Comparing the model with observations, we conclude that the drift direction of χ might oscillate many times during the lifetime of a pulsar. The evolution of χ is not sufficient to explain the rotation behavior of the Crab pulsar, because the observed χand χ˙ are inconsistent with the values indicated from the timing residuals using this model.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： In the late inspiral phase of a double neutron star (NS) or NS-black hole system in which one NS is a magnetar, the tidal force on the magnetar arisen from its companion will increase dramatically as the binary approaches. The tidal-induced deformation may surpass the maximum that the magnetar's crust can sustain just seconds or subseconds before the coalescence. A catastrophic global crust destruction may thus occur, and the magnetic energy stored in the magnetar's interior will have the opportunity to be released, which would be observed as a superflare with energy 100s of times larger than giant flares of magnetars. Such a mechanism can naturally explain the recently observed precursor of GRB 211211A, including its quasiperiodic oscillation. We predict that in the coming gravitational wave O4/O5 period, there could be a fraction of detected double NS mergers associated with such super flares. If observed, copious information on the structure and magnetic field in an NS interior can be obtained, which is hard to study elsewhere.
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