Evolution implications of neutron star magnetic fields: inferred from pulsars and cyclotron lines of HMXBs

Abstract

The evolution of neutron star (NS) magnetic field (Bfield) has long been an important topic, which is still not yet settled down. Here, we analyze the NS B-fields inferred by the cyclotron resonance scattering features (CRSFs) for the high mass X-ray binaries (HMXBs) and by the magnetic dipole model for the spin-down pulsars. We find that the B-fields of both the 32 NS-HMXBs and 28 young pulsars with the supernova remnants follow the log-normal distributions, with the average values of 3.4 × 10 12 G and 4.1 × 10 12 G respectively, which are further verified to come from the same continuous distribution by the statistical tests. These results declaim that the two methods of measuring NS B-fields are reliable for the above two groups of samples. In addition, since the NS-HMXBs have experienced the spin-down phase as the normal pulsars without accretion and then the spin-up phase by accretion, their ages should be about million years (Myrs). Our statistical facts imply that the B-fields of NS-HMXBs have little decayed in their non-accretion spin-down phases of ∼ Myrs, as well as in their accretion phases of ∼ 0.1 Myrs.

Statistical tests of young radio pulsars with/without supernova remnants: implying two origins of neutron stars

“…Additionally, because the periods for most rotating radio transients (RRATs) and intermittent pulsars are greater than 0.5 s (McLaughlin et al 2006;Kramer et al 2006), we eliminate these special radio pulsars from our samples. Therefore, we regard the radio pulsars with spin periods of less than 0.5 s to be the young pulsar, and they are roughly consistent with the arguments based on that their magnetic fields are comparable with those measured by cyclotron absorption lines of X-rays (Ye et al 2019).…”

Evolution of neutron star magnetic fields

“…Thus, strong magnetic fields measured for NSs in HMXBs (B p ∼ 10 12 G) indicate that there is no significant magnetic field decay on timescales up to ≈ 2 × 10 8 years [146]. This is also in correspondence with results in [144] where the authors also concluded that fields 10 13 G do not decay significantly.…”

“…In both cases there are two independent approaches to measure the NS magnetic field: (1) based on NS spin properties and X-ray luminosity, and (2) based on X-ray absorption lines (see e.g. [144] and references therein). The first approach usually suggests that the NS spin period stays close to the equilibrium period.…”

Evolution of Neutron Star Magnetic Fields

“…Thus, strong magnetic fields measured for NSs in HMXBs (B p ∼ 10 12 G) indicate that there is no significant magnetic field decay on timescales of up to ≈2 × 10 8 years [149]. This is also in correspondence with the results in [147], where the authors also concluded that fields 10 13 G do not decay significantly.…”

“…In both cases, there are two independent approaches to measure the NS magnetic field: (1) based on NS spin properties and X-ray luminosity, and (2) based on X-ray absorption lines (see, for example, [147] and the references therein). The first approach usually suggests that the NS spin period stays close to the equilibrium period.…”