Compton scattering in the optically thick uniform spherical corona around the neutron star in an X-ray binary in two conditions

2021 ◽  
Author(s):  
ChangSheng Shi
Keyword(s):  
Neutron Star ◽  
Energy Distribution ◽  
Compton Scattering ◽  
Physical Process ◽  
Low Energy ◽  
X Ray ◽  
Low Energy Electrons ◽  
Initial Seed

Abstract We consider the Compton scattering in the optically thick uniform spherical corona around a neutron star in an X-ray binary. In the scattering, the low energy seed photons (0.1 ∼ 2.5 keV) are scattered in low energy electrons (2.5 ∼ 10 keV) in the corona in two conditions, i.e. initial seed photons are scattered in a whole corona and scattered in every layer of the corona that are supposed to be divided into many layers. When the same number of input seed photons, the same corona parameters and the same energy distribution of all photons in the two conditions are considered, the approximately same number of output photons can be obtained, which means that there is approximately a transform invariance of layering the Comptonized corona. Thus the scattering in the layers of a multi-layered corona is approximately equal to the scattering in the whole corona by dividing the whole corona into several layers. It means that Compton scattering for the initial seed photons scattered in a whole optically thick spherical corona with uniformly distributed electrons also can be considered as that the multiple Compton scatterings take place in the layers of a multi-layered corona in order approximately, which can be used to explore some physical process in one part of a corona.

scholarly journals Effects of Compton scattering on the neutron star radius constraints in rotation-powered millisecond pulsars

2019 ◽  
Vol 627 ◽  
pp. A39 ◽  
Author(s):  
Tuomo Salmi ◽  
Valery F. Suleimanov ◽  
Juri Poutanen
Keyword(s):  
Angular Distribution ◽  
Neutron Star ◽  
Energy Spectrum ◽  
Compton Scattering ◽  
Electron Scattering ◽  
Exact Formulation ◽  
Millisecond Pulsars ◽  
X Ray ◽  
Synthetic Phase ◽  
Neutron Star Radius

The aim of this work is to study the possible effects and biases on the radius constraints for rotation-powered millisecond pulsars when using Thomson approximation to describe electron scattering in the atmosphere models, instead of using exact formulation for Compton scattering. We compare the differences between the two models in the energy spectrum and angular distribution of the emitted radiation. We also analyse a self-generated, synthetic, phase-resolved energy spectrum, based on Compton atmosphere and the most X-ray luminous, rotation-powered millisecond pulsars observed by the Neutron star Interior Composition ExploreR (NICER). We derive constraints for the neutron star parameters using both the Compton and Thomson models. The results show that the method works by reproducing the correct parameters with the Compton model. However, biases are found in both the size and the temperature of the emitting hotspot, when using the Thomson model. The constraints on the radius are still not significantly changed, and therefore the Thomson model seems to be adequate if we are interested only in the radius measurements using NICER.

Extended X-ray absorption fine-structure analysis of vacuum-deposited amorphous germanium

1989 ◽  
Vol 67 (4) ◽  
pp. 358-364 ◽  
Author(s):  
G. W. Johnson ◽  
D. E. Brodie ◽  
E. D. Crozier
Keyword(s):  
Fine Structure ◽  
Amorphous Materials ◽  
Amorphous Material ◽  
Amorphous Structure ◽  
Low Energy ◽  
X Ray Diffraction ◽  
Two Phase ◽  
Edge Structure ◽  
X Ray ◽  
Low Energy Electrons

In this study, thin films of germanium have been vacuum deposited in four regimes. Care was taken to prepare reproducible films, which required that the partial pressure of water be below 10−8 Torr during deposition (1 Torr = 133.3 Pa). First, films deposited onto substrates held during deposition at a temperature Ts that is below 473 K are amorphous. Once annealed above 423 K, their electrical conductivity and optical band gap are independent of deposition temperature and rate, and of whether or not low-energy electron irradiation of the substrate is used during deposition. This suggests that a well-defined and reproducible structure is being prepared. Second, a "precrystallization regime" is obtained when Ts is between 473 and 513 K. Extended X-ray adsorption fine-structure and X-ray diffraction confirm that this regime is a two-phase mixture of amorphous material and crystallites. Third, films deposited with Ts near 513 K, while using low-energy electrons to bombard the substrate, are amorphous, but these films have different electrical and optical properties from the films m the first regime. From this, we infer that a second well-defined amorphous structure exists. Fourth, films deposited with Ts above 513 K are polycrystalline. Extended X-ray adsorption fine-structure and X-ray adsorption near-edge structure could not distinguish between the two amorphous materials in the first and third regimes.

scholarly journals Symmetric and triangle-shaped variability of blazars

2014 ◽  
Vol 10 (S313) ◽  
pp. 97-98
Author(s):  
Kenji Yoshida
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Low Energy ◽  
Light Curves ◽  
X Ray ◽  
High Energy Electrons ◽  
Flux Variability ◽  
Low Energy Electrons ◽  
Flux Increase ◽  
Rise Phase

AbstractSymmetric and triangle-shaped flux variability in X-ray and gamma-ray light curves is observed from many blazars. We derived the X-ray spectrum changing in time by using a kinetic equation of high energy electrons. Giving linearly changing the injection of low energy electrons into accelerating and emitting region, we obtained the preliminary results that represent the characteristic X-ray variability of the linear flux increase with hardening in the rise phase and the linear decrease with softening in the decay phase.

Influence of anisotropy of Compton scattering on low energy x-ray reflection

2004 ◽  
Vol 37 (16) ◽  
pp. 2314-2317 ◽  
Author(s):  
D M Davidovi ◽  
J Vukani ◽  
D Arsenovi
Keyword(s):  
Compton Scattering ◽  
Low Energy ◽  
X Ray

scholarly journals On the spin-up events and spin direction of the X-ray pulsar GX 301-2

2020 ◽  
Vol 496 (3) ◽  
pp. 3991-3995
Author(s):  
Jiren Liu
Keyword(s):  
Angular Momentum ◽  
Neutron Star ◽  
Orbital Motion ◽  
Low Energy ◽  
Slow Rotation ◽  
Scattering Process ◽  
X Ray ◽  
Spin Reversal ◽  
Stream Model ◽  
Orbital Spin

ABSTRACT Recently, a retrograde neutron star is proposed for the classical wind-fed X-ray pulsar, GX 301-2, to explain the orbital spin-up to spin-down reversal near periastron, based on the stream model invoked to explain the pre-periastron flare of GX 301-2 previously. We study in detail three rare spin-up events detected by Fermi/GBM and find that the spin derivatives are correlated with the Swift/BAT fluxes, following a relation of $\dot{\nu }\propto F^{0.75\pm 0.05}$. All the spin-up events of GX 301-2 started about 10 d after the periastron, which is the time needed for tidally stripped gas to reach the neutron star. The slow rotation of the optical companion implies that the accreted matter is likely to have angular momentum in the direction of the orbital motion, as in a Roche lobe-like overflow. As a result, the spin-up events of GX 301-2 would favour accretion of a prograde disc to a prograde neutron star. We also find that the flare of intrinsic X-ray emission of GX 301-2 happened 0.4 d before periastron, while the flare of low-energy emission (2–10 keV) happened about 1.4 d before periastron. The preceding low-energy flare can be explained by stronger absorption of the intrinsic X-ray emission closer to the periastron. This finding weakened the need of the stream model. The pulse fraction of GX 301-2 near periastron is reduced heavily, which is likely caused by Compton-scattering process. Compton reflection from the optical companion might be responsible for the observed orbital spin reversal of GX 301-2.

scholarly journals IGR J17503–2636: a candidate supergiant fast X-ray transient

2019 ◽  
Vol 624 ◽  
pp. A142 ◽  
Author(s):  
C. Ferrigno ◽  
E. Bozzo ◽  
A. Sanna ◽  
G. K. Jaisawal ◽  
J. M. Girard ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Neutron Star ◽  
Energy Distribution ◽  
Power Law ◽  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
X Ray ◽  
Broad Feature

The object IGR J17503–2636 is a hard X-ray transient discovered by INTEGRAL on 2018 August 11. This was the first ever reported X-ray emission from this source. Following the discovery, follow-up observations were carried out with Swift, Chandra, NICER, and NuSTAR. Here we report on the analysis of all of these X-ray data and the results obtained. Based on the fast variability in the X-ray domain, the spectral energy distribution in the 0.5–80 keV energy range, and the reported association with a highly reddened OB supergiant at ∼10 kpc, we conclude that IGR J17503–2636 is most likely a relatively faint new member of the supergiant fast X-ray transients. Spectral analysis of the NuSTAR data revealed a broad feature in addition to the typical power-law with exponential roll-over at high energy. This can be modeled either in emission or as a cyclotron scattering feature in absorption. If confirmed by future observations, this feature would indicate that IGR J17503–2636 hosts a strongly magnetized neutron star with B ∼ 2 × 1012 G.

Low-energy electrons and X-ray irradiation effects on plasma-polymerized allylamine bioactive coatings for stents

2010 ◽  
Vol 95 (2) ◽  
pp. 153-163 ◽  
Author(s):  
Sylvain Massey ◽  
Enrico Gallino ◽  
Pierre Cloutier ◽  
Michaël Tatoulian ◽  
Léon Sanche ◽  
...  
Keyword(s):  
Low Energy ◽  
Irradiation Effects ◽  
Bioactive Coatings ◽  
X Ray ◽  
Low Energy Electrons
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