Braneworld effects in plasma magnetosphere of a slowly rotating magnetized neutron star

2019 ◽  
Vol 28 (10) ◽  
pp. 1950128 ◽  
Author(s):  
Javlon Rayimbaev ◽  
Bobur Turimov ◽  
Bobomurat Ahmedov
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Charge Density ◽  
Production Condition ◽  
Scalar Potential ◽  
Polar Cap ◽  
Radiation Beam ◽  
Electrical Fields ◽  
Analytical Expression ◽  
Surface Magnetic Field

Results of our previous paper [B. V. Turimov, B. J. Ahmedov and A. A. Hakimov, Phys. Rev. D 96 (2017) 104001] show that the effects of brane charges are not negligible in the magnetic field of the magnetized neutron star, in particular at the surface of the star, and increasing the value of brane tidal charges causes an increases in the value of surface magnetic field of magnetized neutron star, that is why it is important to consider the effects of braneworlds on energetic processes in the plasma magnetosphere of the neutron star. In this paper, we have obtained the analytical expression for Goldreich–Julian (GJ) charge density in braneworlds for inclined neutron star by solving Maxwell’s equations and found that the value of GJ charge density decreases in braneworlds. The analytical expression for scalar potential in the polar cap region of the neutron star has also been obtained. It is shown that the values of the parallel accelerating electrical fields increase with the increase of the value of the tidal charge near the surface of the neutron star. The influence of braneworlds on pair production condition on the surface of the neutron star and magnetospheric energy losses due to electromagnetic radiations have also been studied. We have shown how radiation beam becomes narrow due to the effects of braneworlds by studying the particle’s trajectory in the polar cap region in the [Formula: see text]–[Formula: see text] ([Formula: see text].) plane. Numerical calculations for particle motion in the polar cap region show that accelerating distance of charged particle increases up to its maximum value in braneworld in comparison with that in GR, due to additional gravitating behavior of tidal charges.

scholarly journals Plasma magnetosphere of slowly rotating magnetized neutron star in branewold

2019 ◽  
Vol 49 ◽  
pp. 1960019 ◽  
Author(s):  
Rayimbaev Javlon ◽  
Turimov Bobur ◽  
Palvanov Satimbay
Keyword(s):  
Neutron Star ◽  
Electric Field ◽  
Charge Density ◽  
Poisson Equation ◽  
Maxwell Equations ◽  
Scalar Potential ◽  
Parallel Electric Field ◽  
Polar Cap ◽  
Analytical Expression ◽  
Analytical Expressions

The analytical expression for Goldreich-Julian (GJ) charge density at the polar cap of magnetized neutron star has been obtained in braneworlds for inclined neutron star through solving Maxwell equations and shown that the value of GJ charge density decreases with increasing the value of the brane charge. The analytical expressions for scalar potential and parallel electric field on the region greater than the polar cap region of the neutron star have also been obtained by solving Poisson equation in braneworlds.

Particle acceleration and electromagnetic field of deformed neutron stars

2019 ◽  
Vol 35 (09) ◽  
pp. 2050056 ◽  
Author(s):  
Javlon Rayimbaev ◽  
Bobur Turimov ◽  
Figueroa Marcos ◽  
Satimbay Palvanov ◽  
Azamkhan Rakhmatov
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Neutron Star ◽  
Neutron Stars ◽  
Electromagnetic Fields ◽  
Deformation Parameter ◽  
Radio Pulsar ◽  
Slow Rotation ◽  
Polar Cap ◽  
Surface Magnetic Field

Neutron stars (NS)s are astrophysical objects with strong gravitational and electromagnetic fields. Since there are several effects on radiation processes around the star, it is impossible to consider whole effects all together. One way to study the processes is by considering them one by one as a toy model. In this paper, we have investigated the effects of spacetime deformation on the surface magnetic field of the slowly rotating neutron star and its plasma magnetospheric processes, such as the plasma magnetosphere formation around the star. At first, the approximate vacuum solutions of the Maxwell equations for the electromagnetic fields of a magnetized neutron star in a slowly rotating deformed spacetime metric have been obtained. It has been shown that the positive deformation parameter leads to an increase in the value of the (surface) magnetic field at the near zone of the neutron star, while the effect of the negative deformation parameter is vice versa. We have also considered the electric field of the slowly rotating neutron star in the spacetime. In the slow rotation approximation, we have studied the particle acceleration in the polar cap zone, considering the effect of deformation of spacetime on the [Formula: see text]-Lorentz factor of a relativistic charged particle. It is shown that in the case of the positive deformation, an additional gravity occurs around the NS. The effects of spacetime deformation on magneto-dipolar radiation of radio pulsars and polar cap size have also been studied and shown that negative deformation of spacetime increased the radiation luminosity and as positive deformation increases, the luminosity decreases. Size of polar cap region of a neutron star, where magnetic field lines open, increases with increasing the value of the deformation parameter [Formula: see text]. Moreover, we have studied the influence of the spacetime deformation on the death line for radio pulsar, which separates the region in [Formula: see text] [Formula: see text] diagram, where the pulsar can or cannot radiate in radio band (create pair production) through inverse compton scattering (ICS). It is shown that the negative (positive) deformation shifts upward (downward) the death line, which means that even a small negative (positive) deformation of spacetime may cause to be radio-quite (be radio load) the radio pulsar which is lying on the death line (in [Formula: see text] diagram) in the GR frame with its corresponding parameters.

scholarly journals An Emission Line in the Hard X-Ray Spectrum of Hercules X-1: Quantized Cyclotron Emission from the Neutron Star

1977 ◽  
Vol 43 ◽  
pp. 34-34
Author(s):  
W. Pietsch ◽  
C. Reppin ◽  
R. Staubert ◽  
J. Truemper ◽  
W. Voges ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Field Strength ◽  
Second Harmonic ◽  
Narrow Line ◽  
Electron Cyclotron Emission ◽  
Polar Cap ◽  
Astrophysical Application ◽  
X Ray ◽  
Cyclotron Emission

A four hour balloon observation of HERC X-l during the 'On-state' in the 35 day cycle was performed on May 3rd, 1976. The 1.24 second pulsations show a pulsed fraction of 58 ± 8% in the 18-31 KeV interval. A pulsed flux (1.24 sec) was discovered in the 31-88 KeV interval with a pulsed fraction of 51 ± 14%. The spectrum of the pulsed flux can be represented up to 50 KeV by an exponential distribution with KT approximately 8 KeV. At approximately 58 KeV a strong and narrow line feature occurs which we interpret as electron cyclotron emission (ΔN = 1 Landau transition) from the polar cap plasma of the rotating neutron star. The corresponding magnetic field strength is approximately 5 x 1012 Gauss, neglecting gravitational red shift. There is evidence for a second harmonic at approximately 110 KeV (ΔN = 2 ).The astrophysical application of this discovery will be discussed in some detail.

scholarly journals A single spark model for PSR J2144−3933

2019 ◽  
Vol 492 (2) ◽  
pp. 2468-2480 ◽  
Author(s):  
Dipanjan Mitra ◽  
Rahul Basu ◽  
George I Melikidze ◽  
Mihir Arjunwadkar
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Single Pulse ◽  
Single Component ◽  
Gap Model ◽  
Acceleration Region ◽  
Polar Cap ◽  
Surface Magnetic Field ◽  
Gap Models ◽  
Vacuum Gap

ABSTRACT The partially screened vacuum gap model (PSG) for the inner acceleration region in normal radio pulsars, a variant of the pure vacuum gap model, attempts to account for the observed thermal X-ray emission from polar caps and the subpulse drifting time-scales. We have used this model to explain the presence of death lines and extreme location of PSR J2144−3933 in the $P{-}\dot{P}$ diagram. This model requires maintaining the polar cap near a critical temperature and the presence of non-dipolar surface magnetic field to form the inner acceleration region. In the PSG model, thermostatic regulation is achieved by sparking discharges, which are a feature of all vacuum gap models. We demonstrate that non-dipolar surface magnetic field reduces polar cap area in PSR J2144−3933 such that only one spark can be produced and is sufficient to sustain the critical temperature. This pulsar has a single-component profile over a wide frequency range. Single-pulse polarimetric observations and the rotating vector model confirm that the observer’s line of sight traverses the emission beam centrally. These observations are consistent with a single spark operating within framework of the PSG model leading to single-component emission. Additionally, single-pulse modulations of this pulsar, including lack of subpulse drifting, presence of single-period nulls and microstructure, are compatible with a single spark either in PSG or in general vacuum gap models.

scholarly journals Determining the neutron star surface magnetic field strength of two Z sources

2012 ◽  
Vol 8 (S290) ◽  
pp. 203-204
Author(s):  
Guoqiang Ding ◽  
Chunping Huang ◽  
Yanan Wang
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Extreme Position ◽  
X Ray ◽  
Surface Magnetic Field ◽  
Axis Of Rotation ◽  
Star Surface ◽  
Z Sources

AbstractFrom the extreme position of disk motion, we infer the neutron star (NS) surface magnetic field strength (B0) of Z-source GX 17+2 and Cyg X-2. The inferred B0 of GX 17+2 and Cyg X-2 are ~(1–5)×108 G and ~(1–3)×108 G, respectively, which are not inferior to that of millisecond X-ray pulsars or atoll sources. It is likely that the NS magnetic axis of Z sources is parallel to the axis of rotation, which could result in the lack of pulsations in these sources.

scholarly journals On the Nature of Magnetars

2004 ◽  
Vol 218 ◽  
pp. 265-266
Author(s):  
Ya. N. Istomin
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Magnetic Fields ◽  
Electromagnetic Fields ◽  
Gamma Ray ◽  
X Ray ◽  
Surface Magnetic Field ◽  
The Core ◽  
Neutron Star Crust ◽  
High Magnitude

The electromagnetic fields of magnetodipole radiation can penetrate to the conducting matter of a neutron star crust and create there electric currents and tangential magnetic fields of high magnitude. The solution obtained here has the form of surface magnetic field discontinuities propagating through the crust to the core. This model explains the phenomena of magnetars — Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars.

scholarly journals A New Model of “Magnetar”

2004 ◽  
Vol 218 ◽  
pp. 271-272
Author(s):  
I. F. Malov ◽  
G. Z. Machabeli ◽  
V. M. Malofeev
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Gamma Ray ◽  
Drift Waves ◽  
New Model ◽  
X Ray ◽  
Surface Magnetic Field ◽  
Light Cylinder

A new model is proposed to explain the main properties of anomalous X-ray pulsars and soft gamma-ray repeaters, in terms of drift waves in the vicinity of the light cylinder of a neutron star with a surface magnetic field ∼ 1012 G.

scholarly journals Broadband spectral investigations of SGR J1550–5418 bursts

2012 ◽  
Vol 8 (S291) ◽  
pp. 444-446
Author(s):  
Lin Lin ◽  
Ersin Göğüş
Keyword(s):  
Magnetic Field ◽  
Spectral Analysis ◽  
Neutron Star ◽  
Hot Spots ◽  
Gamma Ray ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Surface Magnetic Field ◽  
First Time ◽  
Burst Emission

AbstractWe present the results of our broadband (0.5 − 200 keV) spectral analysis of 42 SGR J1550–5418 bursts simultaneously detected with the Swift/X-ray Telescope (XRT) and the Fermi/Gamma-ray Burst Monitor (GBM), during the 2009 January active episode of the source. We find that, on average, the burst spectra are better described with two blackbody functions than with the Comptonized model. Thus, our joint XRT/GBM analysis clearly shows for the first time that the SGR J1550–5418 burst spectra might naturally be expected to exhibit a more truly thermalized character, such as a two-blackbody or even a multi-blackbody signal. We also studied the spin phase of the XRT burst emission, which indicate that the burst emitting sites on the neutron star need not to be co-located with hot spots emitting the bulk of the persistent X-ray emission and the surface magnetic field of SGR J1550–5418 is likely non-uniform over the emission zone.

scholarly journals Observational Consequences of Polar Cap Theories

1981 ◽  
Vol 95 ◽  
pp. 99-102
Author(s):  
Andrew F. Cheng
Keyword(s):  
Magnetic Field ◽  
Temporal Modulation ◽  
Polar Cap ◽  
Ion Outflow ◽  
X Ray ◽  
Surface Magnetic Field ◽  
Polar Caps ◽  
Temperature Oscillations ◽  
Field Lines ◽  
Positive Ion

Possible observational consequences are outlined for pulsar models with positive ion outflow at the polar caps together with e+-e− pair production discharge there. A characteristic thermal x-ray luminosity is maintained by discharge heating in regions of positive current outflow. A decrease in polar cap thermal x-ray emission may occur during radio nulls. Two mechanisms are identified which can yield temporal modulation of the outflowing ion and e+-e− plasmas, and which may lead to modulation of coherent radio emission on observed microstructure timescales. These are: (1) polar cap temperature oscillations which occur preferentially in pulsars of low surface magnetic field, and (2) the tendency of sparks to migrate toward the convex side of the magnetic field lines.

Sign in / Sign up

Export Citation Format

Share Document