Open AccessThe bottom magnetic field and magnetosphere evolution of neutron star in low‐mass X‐ray binary
Author(s) -
Zhang C. M.,
Kojima Y.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2005.09802.x
Subject(s) - physics , neutron star , magnetosphere , accretion (finance) , astrophysics , intermediate polar , pulsar , millisecond pulsar , polar , radius , magnetic field , x ray binary , astronomy , white dwarf , stars , computer security , quantum mechanics , computer science
The accretion‐induced neutron star (NS) magnetic field evolution is studied through considering the accretion flow to drag the field lines aside and dilute the polar‐field strength, and as a result the equatorial field strength increases, which is buried inside the crust on account of the accretion‐induced global compression of star crust. The main conclusions of model are as follows: (i) the polar field decays with increase in the accreted mass; (ii) the bottom magnetic field strength of about 10 8 G can occur when the NS magnetosphere radius approaches the star radius, and it depends on the accretion rate as ; and (iii) the NS magnetosphere radius decreases with accretion until it reaches the star radius, and its evolution is little influenced by the initial field and the accretion rate after accreting ∼0.01 M ⊙ , which implies that the magnetosphere radii of NSs in low‐mass X‐ray binaries would be homogeneous if they accreted the comparable masses. As an extension, the physical effects of the possible strong magnetic zone in the X‐ray NSs and recycled pulsars are discussed. Moreover, the strong magnetic fields in the binary pulsars PSR 1831−00 and PSR 1718−19 after accreting about 0.5 M ⊙ in the binary‐accretion phase, 8.7 × 10 10 and 1.28 × 10 12 G , respectively, can be explained through considering the incomplete frozen flow in the polar zone. As an expectation of the model, the existence of the low magnetic field (∼3 × 10 7 G) NSs or millisecond pulsars is suggested.