The magnetic field of an isolated neutron star from X-ray cyclotron absorption lines

Nature ◽  
2003 ◽  
Vol 423 (6941) ◽  
pp. 725-727 ◽  
Author(s):  
G. F. Bignami ◽  
P. A. Caraveo ◽  
A. De Luca ◽  
S. Mereghetti
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Absorption Lines ◽  
X Ray ◽  
Cyclotron Absorption ◽  
The Magnetic Field

scholarly journals Early neutron star evolution in high-mass X-ray binaries

2020 ◽  
Vol 494 (1) ◽  
pp. 44-49 ◽  
Author(s):  
Wynn C G Ho ◽  
M J P Wijngaarden ◽  
Nils Andersson ◽  
Thomas M Tauris ◽  
F Haberl
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Thermal Emission ◽  
Equilibrium Phase ◽  
High Mass ◽  
X Ray ◽  
Spin Period ◽  
Long Duration ◽  
X Ray Binaries ◽  
The Magnetic Field

ABSTRACT The application of standard accretion theory to observations of X-ray binaries provides valuable insights into neutron star (NS) properties, such as their spin period and magnetic field. However, most studies concentrate on relatively old systems, where the NS is in its late propeller, accretor, or nearly spin equilibrium phase. Here, we use an analytic model from standard accretion theory to illustrate the evolution of high-mass X-ray binaries (HMXBs) early in their life. We show that a young NS is unlikely to be an accretor because of the long duration of ejector and propeller phases. We apply the model to the recently discovered ∼4000 yr old HMXB XMMU J051342.6−672412 and find that the system’s NS, with a tentative spin period of 4.4 s, cannot be in the accretor phase and has a magnetic field B > a few × 1013 G, which is comparable to the magnetic field of many older HMXBs and is much higher than the spin equilibrium inferred value of a few × 1011 G. The observed X-ray luminosity could be the result of thermal emission from a young cooling magnetic NS or a small amount of accretion that can occur in the propeller phase.

scholarly journals Effect of Photon Rocket in X-ray Binaries

2000 ◽  
Vol 177 ◽  
pp. 653-654
Author(s):  
V. D. Pal’shin ◽  
A. I. Tsygan
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Gravitational Attraction ◽  
Dipolar Field ◽  
X Ray ◽  
The Galaxy ◽  
Star Surface ◽  
X Ray Binaries ◽  
The Magnetic Field

AbstractIt is shown that X-ray binaries can be accelerated by their own radiation. It is possible if the magnetic field of a neutron star in a binary differs from the dipolar field. Asymmetric X-ray emission generated due to accretion of matter onto a neutron star surface creates an accelerating force. Its magnitude can be comparable or even larger than gravitational attraction of the binary to the Galaxy.

scholarly journals Spin evolution of neutron stars in wind-fed high-mass X-ray binaries

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Shigeyuki Karino
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Neutron Stars ◽  
Wind Velocity ◽  
High Mass ◽  
Quasi Equilibrium ◽  
Pulse Period ◽  
X Ray ◽  
Spin Evolution ◽  
The Magnetic Field

Abstract The observed X-ray pulse period of OB-type high-mass X-ray binary (HMXB) pulsars is typically longer than 100 seconds. It is considered that the interaction between the strong magnetic field of a neutron star and the wind matter could cause such a long pulse period. In this study, we follow the spin evolution of neutron stars, taking into account the interaction between the magnetic field and wind matter. In this line, as new challenges, we solve the evolution of the magnetic field of the neutron star at the same time, and additionally we focus on the effects of the wind properties of the donor. As a result, evolutionary tracks were obtained in which the neutron star spends some duration in the ejector phase after birth, then rapidly spins down, becomes quasi-equilibrium, and gradually spins up. Such evolution is similar to previous studies, but we found that its dominant physics depends on the velocity of the donor wind. When the wind velocity is fast, the spin-down occurs due to magnetic inhibition, while the classical propeller effect and settling accretion shell causes rapid spin-down in the slow wind accretion. Since the wind velocity of the donor could depend on the irradiated X-ray luminosity, the spin evolution track of the neutron star in a wind-fed HMXB could be more complicated than considered.

scholarly journals MEASURING MAGNETIC FIELD OF NEUTRON STAR 4U 0115+63 WITH CYCLOTRON FEATURES

2013 ◽  
Vol 23 ◽  
pp. 161-164
Author(s):  
SU YAO ◽  
CHENGMIN ZHANG
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Relativistic Effect ◽  
Absorption Lines ◽  
Fundamental Feature ◽  
X Ray ◽  
Measuring Magnetic Field ◽  
Absorption Features ◽  
Main Region ◽  
Just Right

We analyze the 3-80 keV spectrum of X-ray pulsar 4U 0115+63 taken by Rossi X-ray Timing Explorer(RXTE) on April 22nd, 2008. Two absorption features at ~13.5 keV and ~20.5 keV are detected by using cyclotron scattering feature profiles to fit the spectrum, ignoring the inadequate photons of the analyzed data. The fundamental feature is just right between ~11 and ~16 keV. It seems implausible to interprete these absorption lines as cyclotron features because of their inharmonic behavior, even when relativistic effect has been taken into account. But it is possible that the main region where first harmonic line forms is slightly different from the fundamental one.

scholarly journals Redshifted absorption lines from an isolated neutron star

2020 ◽  
Author(s):  
Sergio Campana
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Hydrogen Atmosphere ◽  
Oxygen Absorption ◽  
Spectral Features ◽  
Breeding Ground ◽  
X Ray ◽  
Cyclotron Absorption ◽  
Star Surface ◽  
Absorption Features

Abstract The solid crust constituting the outer layers of a hot neutron star is wrapped by an mm-to-cm thin atmosphere. Even if the atmosphere is so thin, it substantially affects the blackbody spectrum emitted by the surface, resulting in an overall hardening of the emitted spectrum. The composition of the atmosphere has so far remained elusive. Several narrow absorption features have been detected and interpreted as arising from proton (or electron) resonant cyclotron absorption in the neutron star magnetic field. Apart from these, for a Hydrogen atmosphere no spectral features are expected, whereas when it is polluted with metals, absorption features start appearing in soft X-ray spectra. Absorption edges and features have been possibly observed during thermonuclear explosions onto the neutron star surface. Isolated neutron stars represent a breeding ground where to look for absorption features, thanks to their simple X-ray spectra. Here we report on the detection of redshifted Nitrogen and Oxygen absorption features from the closest and brightest isolated neutron star. The lines are ~50 eV wide and their intensity is incompatible from originating in the interstellar path to the neutron star. Lines are redshifted by a common gravitational redshift of z_g=0.216±0.004.

scholarly journals First characterization of Swift J1845.7–0037 with NuSTAR

2020 ◽  
Vol 634 ◽  
pp. A89
Author(s):  
V. Doroshenko ◽  
S. Tsygankov ◽  
J. Long ◽  
A. Santangelo ◽  
S. Molkov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Spectral Analysis ◽  
Neutron Star ◽  
X Ray ◽  
Transient Source ◽  
Broadband Spectrum ◽  
Cyclotron Line ◽  
The Magnetic Field

The hard X-ray transient source Swift J1845.7–0037 was discovered in 2012 by Swift/BAT. However, at that time, no dedicated observations of the source were performed. In October 2019, the source became active again, and X-ray pulsations with a period of ∼199 s were detected with Swift/XRT. This triggered follow-up observations with NuSTAR. Here, we report on the timing and spectral analysis of the source properties using NuSTAR and Swift/XRT. The main goal was to confirm pulsations and search for possible cyclotron lines in the broadband spectrum of the source to probe its magnetic field. Despite highly significant pulsations with period of 207.379(2) s being detected, no evidence for a cyclotron line was found in the spectrum of the source. We therefore discuss the strength of the magnetic field based on the source flux and the detection of the transition to the “cold-disc” accretion regime during the 2012 outburst. Our conclusion is that the source is most likely a highly magnetized neutron star with B ≳ 1013 G at a large distance of d ∼ 10 kpc. The latter is consistent with the nondetection of a cyclotron line in the NuSTAR energy band.

scholarly journals Anomalous diffusion across a tera-Gauss magnetic field in accreting neutron stars

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Russell M. Kulsrud ◽  
Rashid Sunyaev
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Flux Distribution ◽  
Polar Regions ◽  
X Ray ◽  
Princeton University ◽  
Neutron Star Mass ◽  
Field Lines ◽  
Strong Ideal ◽  
The Magnetic Field

When mass falls on the polar regions of a neutron star in a binary X-ray source system, it tends to spread out over the entire surface. A long-standing question in research on this problem is: will the mass be anchored on the magnetic field lines and drag the field with it or is there a special mechanism that allows the mass to slip through the magnetic field lines, leading to much less distortion? As the amount of mass falling on the neutron star can actually be comparable with the neutron star mass, the question of which alternative holds is very important. We suggest an efficient mechanism that will allow the mass to slip through the lines. The mechanism is based on a strong ideal Schwarzschild (Structure and Evolution of the Stars. Princeton University Press, 1958) instability. As the instability itself is ideal, it cannot directly force the mass to slip though the lines. However, it can create a cascade of eddies whose scale extends down to a resistive scale, at the same time mixing the field lines up without breaking them. On this scale the mass can cross the lines. This instability is efficient enough that it can produce a mass flow in the plasma without growing to a large amplitude but saturates at a small one. The instability determines the mass per flux distribution of the accumulated material on different lines so that the equilibrium is marginal to the instability on every line. This makes the equilibrium unique. Thus, as the extra mass on the neutron star grows, the state of the outer shell proceeds through a sequence of unique critically unstable equilibria. In an appendix, an attempt is made to track the critical equilibria over long times.

scholarly journals Observations of GRO J1744–28 in quiescence with XMM-Newton

2020 ◽  
Vol 643 ◽  
pp. A62
Author(s):  
V. Doroshenko ◽  
V. Suleimanov ◽  
S. Tsygankov ◽  
J. Mönkkönen ◽  
L. Ji ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Binary System ◽  
Galactic Center ◽  
Optical Counterpart ◽  
X Ray ◽  
Upper Limit ◽  
Dipole Term ◽  
The Magnetic Field

We report on the deep observations of the “bursting pulsar” GRO J1744–28, which were performed with XMM-Newton and aimed to clarify the origin of its X-ray emission in quiescence. We detect the source at a luminosity level of ∼1034 erg s−1 with an X-ray spectrum that is consistent with the power law, blackbody, or accretion-heated neutron star atmosphere models. The improved X-ray localization of the source allowed us to confirm the previously identified candidate optical counterpart as a relatively massive G/K III star at 8 kpc close to the Galactic center, implying an almost face-on view of the binary system. Although we could only find a nonrestricting upper limit on the pulsed fraction of ∼20%, the observed hard X-ray spectrum and strong long-term variability of the X-ray flux suggest that the source is also still accreting when not in outburst. The luminosity corresponding to the onset of centrifugal inhibition of accretion is thus estimated to be at least two orders of magnitude lower than previously reported. We discuss this finding in the context of previous studies and argue that the results indicate a multipole structure in the magnetic field with the first dipole term of ∼1010 G, which is much lower than previously assumed.

scholarly journals Properties of the transient X-ray pulsar Swift J1816.7–1613 and its optical companion

2019 ◽  
Vol 622 ◽  
pp. A198 ◽  
Author(s):  
Armin Nabizadeh ◽  
Sergey S. Tsygankov ◽  
Dmitrij I. Karasev ◽  
Juhani Mönkkönen ◽  
Alexander A. Lutovinov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Energy Spectrum ◽  
Timing Analysis ◽  
Broad Band ◽  
Type I ◽  
Quiescent State ◽  
Band Energy ◽  
X Ray ◽  
Cyclotron Absorption

We present results of investigation of the poorly studied X-ray pulsar Swift J1816.7–1613 during its transition from the type I outburst to the quiescent state. Our studies are based on the data obtained from X-ray observatories Swift, NuSTAR, and Chandra alongside with the latest IR data from UKIDSS/GPS and Spitzer/GLIMPSE surveys. The aim of the work is to determine the parameters of the system, namely the strength of the neutron star magnetic field and the distance to the source, which are required for the interpretation of the source behaviour in the framework of physically motivated models. No cyclotron absorption line was detected in the broad-band energy spectrum. However, the timing analysis hints at the typical for the X-ray pulsars magnetic field from a few ×1011 to a few ×1012 G. We also estimated the type of the IR-companion as a B0-2e star located at a distance of 7–13 kpc.

scholarly journals The Nature and Evolutionary Status of GRO J1744–28

1997 ◽  
Vol 163 ◽  
pp. 289-299
Author(s):  
P. C. Joss ◽  
S. Rappaport
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Neutron Star ◽  
Neutron Stars ◽  
Evolutionary Status ◽  
Type I ◽  
Core Mass ◽  
X Ray ◽  
The Magnetic Field

AbstractGRO J1744–28 is the first known X-ray source to display both bursts and periodic pulsations. This source may thus provide crucial clues that will lead to an understanding of the differences in the nature of the X-ray variability among accreting neutron stars. We deduce that the magnetic field of the neutron star is relatively weak (~ 8 × 1010G) but, nevertheless, sufficiently strong to funnel the accretion flow onto the magnetic polar caps and suppress the thermonuclear flashes that would otherwise give rise to type I X-ray bursts. We also present a series of interrelated arguments which demonstrate that the observed bursts are of type II and probably result from an instability associated with the interaction of the neutron-star magnetic field with the inner edge of the accretion disk. From these results, we infer that X-ray pulsars, GRO J1744–28, the Rapid Burster, and the type I X-ray bursters may form a sequence of possible behaviors among accreting neutron stars, with the strength of the magnetic field serving as the crucial parameter that determines the mode of X-ray variability. The companion star in the GRO J1744–28 binary system is probably a very low-mass (~ 0.2M⊙) giant that is in the final stages of losing its hydrogen-rich envelope. We have carried out binary evolution calculations which show that (1) if the mass of the giant was ~ 1M⊙when mass transfer onto the neutron star commenced, then the orbital period and the core mass of the giant have increased from ~ 1 to ~ 11.8 days and from ~ 0.15 to ~ 0.21M⊙, respectively, during the mass-transfer epoch, which has lasted for ~ 8 × 108yr, (2) the present long-term average X-ray luminosity is ~ 4 × 1036ergs s−1, which is at least two orders of magnitude lower than the luminosity at the peak of the transient outburst, and (3) the predicted long-term equilibrium rotation rate of the neutron star is remarkably close to the observed pulse rate. The transient nature of GRO J1744–28 may well be related to the final stages of dissipation of the envelope of the giant companion.

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