scholarly journals An X-Ray Microlensing Test of AU-Scale Accretion Disk Structure in Q2237+0305

1998 ◽  
Vol 501 (1) ◽  
pp. L41-L44 ◽  
Author(s):  
Atsunori Yonehara ◽  
Shin Mineshige ◽  
Tadahiro Manmoto ◽  
Jun Fukue ◽  
Masayuki Umemura ◽  
...  
Keyword(s):  
Accretion Disk ◽  
X Ray ◽  
Disk Structure

scholarly journals Orbital motion and quasi-quantized disk around rotating neutron stars

2014 ◽  
Vol 23 (06) ◽  
pp. 1450053 ◽  
Author(s):  
Joan Jing Wang ◽  
Hsiang-Kuang Chang
Keyword(s):  
Accretion Disk ◽  
Orbital Motion ◽  
Photon Polarization ◽  
X Ray ◽  
Frame Dragging ◽  
Accretion Flows ◽  
Promising Tool ◽  
Disk Structure ◽  
Low Mass ◽  
Inner Region

In accreting neutron star (NS) low-mass X-ray binary (LMXB) systems, NS accretes material from its low-mass companion via a Keplerian disk. In a viscous accretion disk, inflows orbit the NS and spiral in due to dissipative processes, such as the viscous process and collisions of elements. The dynamics of accretion flows in the inner region of an accretion disk is significantly affected by the rotation of NS. The rotation makes NS, thus the spacetime metric, deviate from the originally spherical symmetry, and leads to gravitational quadrupole, on one hand. On the other hand, a rotating NS drags the local inertial frame in its vicinity, which is known as the rotational frame-dragging effect. In this paper, we investigate the orbital motion of accretion flows of accreting NS/LMXBs and demonstrate that the rotational effects of NS result in a band of quasi-quantized structure in the inner region of the accretion disk, which is different, in nature, from the scenario in the strong gravity of black hole arising from the resonance for frequencies related to epicyclic and orbital motions. We also demonstrate that such a disk structure may account for frequencies seen in X-ray variability, such as quasi-periodic oscillations (QPOs), and can be a potential promising tool for the investigation of photon polarization.

scholarly journals Discovery of Jet-Induced Soft Lags of XTE J1550-564 during Its 1998 Outburst †

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 8
Author(s):  
Arka Chatterjee ◽  
Broja G. Dutta ◽  
Dusmanta Patra ◽  
Sandip K. Chakrabarti ◽  
Prantik Nandi
Keyword(s):  
Accretion Disk ◽  
Time Lag ◽  
Line Of Sight ◽  
Time Lags ◽  
Radio Flux ◽  
X Ray ◽  
Disk Structure ◽  
Timing Properties

X-ray time lags are complicated in nature. The exact reasons for complex lag spectra are as yet unknown. However, the hard lags, in general, are believed to be originated due to inverse Comptonization process. However, the origin of soft lags remained mischievous. Recent studies on “Disk–Jet Connections” revealed that the jets are also contributing in the X-ray spectral and timing properties in a magnitude which was more than what was predicted earlier. In this article, we first show an exact anticorrelation between X-ray time lag and radio flux for XTE J1550-546 during its 1998 outburst. We propose that the soft lags might be generated due to the change in the accretion disk structure along the line of sight during higher jet activity.

scholarly journals The kHz QPOs as a probe of the X-ray color–color diagram and accretion-disk structure for the atoll source 4U 1728-34

2018 ◽  
Vol 618 ◽  
pp. A181 ◽  
Author(s):  
De-Hua Wang ◽  
Cheng-Min Zhang ◽  
Jin-Lu Qu
Keyword(s):  
Magnetic Field ◽  
Accretion Disk ◽  
Disk Radius ◽  
X Ray ◽  
Corotation Radius ◽  
Disk Structure ◽  
Radiation Distribution ◽  
Island State ◽  
The Magnetic Field ◽  
Radiation Transition

We have taken the kHz QPOs as a tool to probe the correlation between the tracks of X-ray color–color diagram (CCD) and magnetosphere-disk positions for the atoll source 4U 1728-34, based on the assumptions that the upper kHz QPO is ascribed to the Keplerian orbital motion and the neutron star (NS) magnetosphere is defined by the dipole magnetic field. We find that from the island to the banana state, the inner accretion disk gradually approaches the NS surface with the radius decreasing from r ∼ 33.0 km to ∼15.9 km, corresponding to the magnetic field from B(r) ∼ 4.8 × 106 G to ∼4.3 × 107 G. In addition, we note the characteristics of some particular radii of magnetosphere-disk r are: firstly, the whole atoll shape of the CCD links the disk radius range of ∼15.9–33.0 km, which is just located inside the corotation radius of 4U 1728-34 rco (∼34.4 km), implying that the CCD shape is involved in the NS spin-up state. Secondly, the island and banana states of CCD correspond to the two particular boundaries: (I)near the corotation radius at r ∼ 27.2–33.0 km, where the source lies in the island state; (II)near the NS surface at r ∼ 15.9–22.3 km, where the source lies in both the island and banana states. Thirdly, the vertex of the atoll shape in CCD, where the radiation transition from the hard to soft photons occurs, is found to be near the NS surface at r ∼ 16.4 km. The above results suggest that both the magnetic field and accretion environment are related to the CCD structure of atoll track, where the corotation radius and NS hard surface play the significant roles in the radiation distribution of atoll source.

scholarly journals Kilohertz quasi-periodic oscillations as probes of the X-ray color-color diagram and neutron star accretion-disk structure for Z sources

2020 ◽  
Vol 642 ◽  
pp. A117
Author(s):  
De-Hua Wang ◽  
Cheng-Min Zhang ◽  
Jin-Lu Qu ◽  
Shu-Mei Jia
Keyword(s):  
Magnetic Field ◽  
Neutron Star ◽  
Accretion Disk ◽  
Magnetic Energy ◽  
Mass Density ◽  
Periodic Oscillations ◽  
Disk Radius ◽  
X Ray ◽  
Disk Structure ◽  
Z Sources

Based on the detected kilohertz quasi-periodic oscillations (kHz QPOs) in neutron star low-mass X-ray binaries (NS-LMXBs), we investigate the evolution of the NS magnetosphere-disk structure along the Z track in the X-ray color-color diagram (CCD) for luminous Z sources, such as Cyg X-2, GX 5-1, GX 17+2, and Sco X-1. We find that the magnetosphere-disk radius r inferred by kHz QPOs for all the sources shows a monotonically decreasing trend along the Z track from the horizontal branch (HB) to the normal branch (NB), implying that the dominated radiation components may dramatically change as the accretion disk moves toward the NS surface. In addition, the specific radius that corresponds to the HB/NB vertex is found to be around r ∼ 20 km, implying a potential characteristic position of transiting for the X-ray radiation mode. Furthermore, we find that the NBs that occur near the NS surface have a radius of r ∼ 16−20 km, which is systematically smaller than those of HBs that have radii of r ∼ 20−29 km. To interpret the relation between the CCD properties and the special magnetosphere-disk radii of Z sources, we suggest that the magnetic field lines corresponding to NB are “frozen-in” to the plasma, and move further inward with the shrinking of the NS magnetosphere-disk radius and pile up near the NS surface. They then form a strong magnetic field region around r ∼ 16−20 km, where the high magnetic energy density and high plasma mass density may dominate the radiation process in NB.

scholarly journals X‐Ray Light Curves and Accretion Disk Structure of EX Hydrae

2005 ◽  
Vol 628 (2) ◽  
pp. 946-952 ◽  
Author(s):  
R. Hoogerwerf ◽  
N. S. Brickhouse ◽  
C. W. Mauche
Keyword(s):  
Accretion Disk ◽  
Light Curves ◽  
X Ray ◽  
Disk Structure

scholarly journals Suzaku studies of microquasars

2010 ◽  
Vol 6 (S275) ◽  
pp. 242-249
Author(s):  
Yoshihiro Ueda ◽  
Megumi Shidatsu
Keyword(s):  
Spectral Analysis ◽  
Accretion Disk ◽  
Energy Resolution ◽  
Broad Band ◽  
High Energy ◽  
High Energy Resolution ◽  
Jet Formation ◽  
X Ray ◽  
Disk Structure ◽  
Accretion Rates

AbstractWe report our recent results from multiwavelengths studies of microquasars, focusing on X-ray data of GX 339–4 and GRS 1915+105 obtained with Suzaku and other observatories. The broad band coverage and high energy resolution achieved with Suzaku (or a combination of Chandra/HETGS and RXTE) enable us to perform the most reliable spectral analysis both on iron-K features and continuum, and thus to best constrain the accretion disk structure of microquasars and its relation to the jet formation at various mass accretion rates.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

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