Rotochemical heating originates in the deviation from beta equilibrium due to spin-down compression, which is closely related to the dipole magnetic field. We numerically calculate the deviation from chemical equilibrium and thermal evolution of neutron stars with decaying magnetic fields. We find that the power-law long term decay of the magnetic field slightly affects the deviation from chemical equilibrium and surface temperature. However, the magnetic decay leads to older neutron stars that could have a different surface temperature with the same magnetic field strength. That is, older neutron stars with a low magnetic field(108G) could have a lower temperature even with rotochemical heating in operation, which probably explains the lack of other observations on older millisecond pulsars with higher surface temperature,except millisecond pulsar J0437–4715.
We study the effect of dark matter heating on the temperature of typical strange star(SS hereafter)(M=1.4 M⊙,R=10 km)in normal phase(NSS hereafter)and in a possible existing colour-flavour locked(CFL)phase(CSS hereafter).For NSS,the influence of dark matter heating is ignored until roughly 107yr.After 107yr,the dark matter heating is dominant that significantly delays the star cooling,which maintains a temperature much higher than that predicted by standard cooling model for old stars.Especially for CSS,the emissivity of dark matter will play a leading role after roughly 104yr,which causes the temperature to rise.This leads to the plateau of surface temperature appearing in～106.5yr which is earlier than that of NSS(～107yr).
Interstellar scattering causes broadening and distortion in the mean pulse profiles and polarization position angle(PPA)curves of pulsars,especially pulse profiles observed at lower frequencies.This paper implements a method to recover the pulse profiles and PPA curves of five pulsars which have obvious scattered pulse profiles at lower frequency.It reports a simulation to show the scattering and descattering of pulse profiles and PPA curves,and as a practical application the lower frequency profiles and PPA curves of PSR 1356-60,PSR 1831-03,PSR 1838+04,PSR 1859+03 and PSR 1946+35 are obtained.It is found that the original pulse profiles and PPA curves can be recovered.
The Five-hundred-meter Aperture Spherical radio Telescope(FAST) has the potential to discover many new pulsars and new phenomena. In this paper we mainly concentrate on how FAST can impact study of the pulsar emission mechanism and magnetospheric dynamics. Several observational programs heading to this direction are reviewed. To make full use of the superior performance of FAST and maximize the scientific outcome, these programs can be arranged in different phases of FAST according to their demands for observational conditions. We suggest that programs can be performed following the test phase, which are observations of multifrequency mean pulse profiles, anomalous X-ray pulsars(AXPs)/soft gamma-ray repeaters(SGRs), mode changing, drifting subpulse and nulling. The long-term monitoring can be carried out for mode changing, AXPs/SGRs and precessional pulsars. Others programs, including polarization observations of radio and γ-ray pulsars, searching for weak pulse components, and multifrequency observations of subpulse drifting, microstructure and giant pulses, can be conducted in all the normal operating phases(the first and second phases). These programs will push forward the frontier in this field in different respects. The search for sub-millisecond pulsars and follow-up observations of their emission properties are very important projects for FAST, but they may be covered by other papers in this mini-volume; therefore,they are not discussed here.
Hong-Guang WangGuo-Jun QiaoYuan-Jie DuJi-Guang LuRen-Xin XuKe-Jia LeeXiong-Wei Liu
Since there is a large population of massive O/B stars and putative neutron stars(NSs) located in the vicinity of the Galactic Center(GC),intermediate-mass X-ray binaries(IMXBs) constituted by an NS and a B-type star probably exist there.We investigate the evolutions of accreting NSs in IMXBs(similar to M82 X-2) with a ~ 5.2 M⊙companion and orbital period■ 2.53 d.By adopting a mildly super-Eddington rate M= 6 × 10^(-8) M⊙yr^(-1) for the early Case B Roche-lobe overflow(RLOF)accretion,we find that only in accreting NSs with quite elastic crusts(slippage factor s = 0.05) can the toroidal magnetic fields be amplified within 1 Myr,which is assumed to be the longest duration of the RLOF.These IMXBs will evolve into NS+white dwarf(WD) binaries if they are dynamically stable.However,before the formation of NS+WD binaries,the high stellar density in the GC will probably lead to frequent encounters between the NS+ evolved star binaries(in post-early Case B mass transfer phase)and NSs or exchange encounters with other stars,which may produce single NSs.These NSs will evolve into magnetars when the amplified poloidal magnetic fields diffuse out to the NS surfaces.Consequently,our results provide a possible explanation for the origin of the GC magnetar SGR 1745–2900.Moreover,the accreting NSs with s > 0.05 will evolve into millisecond pulsars(MSPs).Therefore,our model reveals that the GC magnetars and MSPs could both originate from a special kind of IMXB.
We study the dispersion relation of the excitation mode in a spin-polarized Fermi gas.In the frame of the imaginarytime finite temperature field theory,the polarization tensor is calculated by taking the random phase approximation.The population imbalance effects on the dispersion relation of the excitation mode and the spin-spin correlation susceptibility are investigated.The numerical results in terms of the imbalance ratio indicate the polarization effects on the dispersion relation and susceptibility χ.
