Modelling the spin equilibrium of neutron stars in low‐mass X‐ray binaries without gravitational radiation

  title={Modelling the spin equilibrium of neutron stars in low‐mass X‐ray binaries without gravitational radiation},
  author={Nils Andersson and Kostas Glampedakis and Brynmor Haskell and A.L.Watts},
  journal={Monthly Notices of the Royal Astronomical Society},
In this paper we discuss the spin equilibrium of accreting neutron stars in low-mass X-ray binaries (LMXBs). We demonstrate that, when combined with a naive spin-up torque, the observed data lead to inferred magnetic fields which are at variance with those of Galactic millisecond radio pulsars. This indicates the need for either additional spin-down torques (e.g. gravitational radiation) or an improved accretion model. We show that a simple consistent accretion model can be arrived at by… 

Figures and Tables from this paper

Evolution of The Spin Periods of Neutron Stars in Low Mass X-ray Binaries
Abstract We present a numerical analysis of the spin evolution of neutron stars in low-mass X-ray binaries, trying to explain the discrepancy in the spin period distribution between observations of
Population synthesis of accreting neutron stars emitting gravitational waves
The fastest-spinning neutron stars in low-mass X-ray binaries, despite having undergone millions of years of accretion, have been observed to spin well below the Keplerian break-up frequency. We
Gravitational waves from rapidly rotating neutron stars
Rapidly rotating neutron stars in Low Mass X-ray Binaries have been proposed as an interesting source of gravitational waves. In this chapter we present estimates of the gravitational wave emission
Modelling spin-up episodes in accreting millisecond X-ray pulsars
Accreting millisecond X-ray pulsars are known to provide a wealth of physical information during their successive states of outburst and quiescence. Based on the observed spin-up and spin-down
Constraining the physics of the r-mode instability in neutron stars with X-ray and ultraviolet observations
Rapidly rotating neutron stars in low-mass X-ray binaries may be an interesting source of gravitational waves (GWs). In particular, several modes of stellar oscillation may be driven unstable by GW
Asymmetric accretion and thermal ‘mountains’ in magnetized neutron star crusts
Accreting neutron stars are one of the main targets for continuous gravitational wave searches, as asymmetric accretion may lead to quadrupolar deformations, or `mountains', on the crust of the star,
On the Magnetic Field of the Ultraluminous X-Ray Pulsar M82 X-2
The discovery of the ultraluminous X-ray pulsar M82 X-2 has stimulated lively discussion on the nature of the accreting neutron star. In most of the previous studies the magnetic field of the neutron
The impact of neutron star spin on X-ray spectra
We investigate whether the intrinsic spin of neutron stars leaves an observable imprint on the spectral properties of X-ray binaries. To evaluate this we consider a sample of nine NSs for which the
A millisecond pulsar is a neutron star that has been substantially spun up by accretion from a binary companion. A previously unrecognized factor governing the spin evolution of such pulsars is the
Torque Enhancement, Spin Equilibrium, and Jet Power from Disk-Induced Opening of Pulsar Magnetic Fields
The interaction of a rotating star's magnetic field with a surrounding plasma disk lies at the heart of many questions posed by neutron stars in X-ray binaries. We consider the opening of stellar


Accretion by rotating magnetic neutron stars. III. Accretion torques and period changes in pulsating X-ray sources.
We use the solutions of the two-dimensional hydromagnetic equations obtained previously to calculate the torque on a magnetic neutron star accreting from a Keplerian disk. We find that the magnetic
The Disk-Magnetosphere Interaction in the Accretion-powered Millisecond Pulsar SAX J1808.4–3658
The recent discovery of the first known accretion-powered millisecond pulsar with the Rossi X-Ray Timing Explorer provides the first direct probe of the interaction of an accretion disk with the
Millisecond X-Ray Pulsars in Low-mass X-Ray Binaries
The discovery of millisecond X-ray pulsars in low-mass X-ray binaries (LMXRBs) with the Rossi X-Ray Timing Explorer (RXTE) has resulted in the determination of the neutron star spin periods to be in
Quasi-periodic X-ray brightness fluctuations in an accreting millisecond pulsar
The measurements establish a clear link between kHz QPOs and stellar spin, but one not predicted by any current model, and suggest that a resonance between the spin and general relativistic orbital and epicyclic frequencies could provide the observed relation between Q POs and spin.
Disk accretion by magnetic neutron stars.
A model for disk accretion by a rotating magnetic neutron star is proposed which includes a detailed description of matter flow in the transition region between the disk and the magnetosphere. It is
Spin-Up of Low Luminosity Low Mass X-ray Binaries
We examine the spin-up of low-luminosity, low-mass X-ray binaries (LMXBs) to millisecond pulsars (MSPs). In the conventional spin-up model of the Ghosh & Lamb type, where the stellar magnetic field
Deformations of accreting neutron star crusts and gravitational wave emission
Motivated by the remarkably narrow range of measured spin frequencies of ∼20 accreting (and weakly magnetic) neutron stars in the Galaxy, Bildsten conjectured that their spin-up had been halted by
Nuclear-powered millisecond pulsars and the maximum spin frequency of neutron stars
Millisecond pulsars are neutron stars that are thought to have been spun-up by mass accretion from a stellar companion. It is not known whether there is a natural brake for this process, or if it
Magnetic Screening in Accreting Neutron Stars
We investigate whether the magnetic field of an accreting neutron star may be diamagnetically screened by the accreted matter. We assume the freshly accumulated material is unmagnetized and calculate
Sonic-Point Model of Kilohertz Quasi-periodic Brightness Oscillations in Low-Mass X-Ray Binaries
Quasi-periodic brightness oscillations (QPOs) with frequencies ranging from ~300 to ~1200 Hz have been discovered in the X-ray emission from 14 neutron stars in low-mass binary systems and from