scholarly journals QPOs and Orbital elements of X-ray binary 4U 0115+63 during the 2017 outburst observed by Insight-HXMT

2021 ◽  
Author(s):  
Y Z Ding ◽  
W Wang ◽  
P Zhang ◽  
Q C Bu ◽  
C Cai ◽  
...  
Keyword(s):  
Wavelet Analysis ◽  
Timing Analysis ◽  
High Energy ◽  
Light Curves ◽  
Orbital Elements ◽  
X Ray ◽  
Spin Period ◽  
Peak Structure ◽  
Q Factors ◽  
Wavelet Spectra

Abstract In this paper, we presented a detailed timing analysis of a prominent outburst of 4U 0115+63 detected by Insight-HXMT in 2017 August. The spin period of the neutron star was determined to be 3.61398 ± 0.00002 s at MJD 57978. We measured the period variability and extract the orbital elements of the binary system. The angle of periastron evolved with a rate of $0.048^\circ \pm 0.003^\circ \rm \, yr^{-1}$. The light curves are folded to sketch the pulse profiles in different energy ranges. A multi-peak structure in 1-10 keV is clearly illustrated. We introduced wavelet analysis into our data analysis procedures to study QPO signals and perform a detailed wavelet analysis in many different energy ranges. Through the wavelet spectra, we report the discovery of a QPO at the frequency ∼10 mHz. In addition, the X-ray light curves showed multiple QPOs in the period of ∼16 − 32 s and ∼67 − 200 s. We found that the ∼100 s QPO was significant in most of the observations and energies. There exist positive relations between X-ray luminosity and their Q-factors and S-factors, while the QPO periods have no correlation with X-ray luminosity. In wavelet phase maps, we found that the pulse phase of ∼67 − 200 s QPO drifting frequently while the ∼16 − 32 s QPO scarcely drifting. The dissipation of oscillations from high energy to low energy was also observed. These features of QPOs in 4U 0115+63 provide new challenge to our understanding of their physical origins.

scholarly journals X-ray spectra and light curves of cooling novae and a nova like

2020 ◽  
Vol 499 (2) ◽  
pp. 3006-3018
Author(s):  
Bangzheng Sun ◽  
Marina Orio ◽  
Andrej Dobrotka ◽  
Gerardo Juan Manuel Luna ◽  
Sergey Shugarov ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Rate ◽  
High Energy ◽  
Gravitational Energy ◽  
Light Curves ◽  
Clear Correlation ◽  
X Rays ◽  
High State ◽  
X Ray ◽  
Low X

ABSTRACT We present X-ray observations of novae V2491 Cyg and KT Eri about 9 yr post-outburst of the dwarf nova and post-nova candidate EY Cyg, and of a VY Scl variable. The first three objects were observed with XMM–Newton, KT Eri also with the Chandra ACIS-S camera, V794 Aql with the Chandra ACIS-S camera and High Energy Transmission Gratings. The two recent novae, similar in outburst amplitude and light curve, appear very different at quiescence. Assuming half of the gravitational energy is irradiated in X-rays, V2491 Cyg is accreting at $\dot{m}=1.4\times 10^{-9}{\!-\!}10^{-8}\,{\rm M}_\odot \,{\rm yr}^{-1}$, while for KT Eri, $\dot{m}\lt 2\times 10^{-10}{\rm M}_\odot \,{\rm yr}$. V2491 Cyg shows signatures of a magnetized WD, specifically of an intermediate polar. A periodicity of  39 min, detected in outburst, was still measured and is likely due to WD rotation. EY Cyg is accreting at $\dot{m}\sim 1.8\times 10^{-11}{\rm M}_\odot \,{\rm yr}^{-1}$, one magnitude lower than KT Eri, consistently with its U Gem outburst behaviour and its quiescent UV flux. The X-rays are modulated with the orbital period, despite the system’s low inclination, probably due to the X-ray flux of the secondary. A period of  81 min is also detected, suggesting that it may also be an intermediate polar. V794 Aql had low X-ray luminosity during an optically high state, about the same level as in a recent optically low state. Thus, we find no clear correlation between optical and X-ray luminosity: the accretion rate seems unstable and variable. The very hard X-ray spectrum indicates a massive WD.

scholarly journals The Spin-Up Rate of the White Dwarf in GK Per

2004 ◽  
Vol 190 ◽  
pp. 120-123
Author(s):  
Christopher W. Mauche
Keyword(s):  
White Dwarf ◽  
Light Curves ◽  
Optical Measurements ◽  
Pulse Period ◽  
X Ray ◽  
Spin Period

AbstractWe use hard X-ray light curves measured by the Chandra HETG and RXTE PCA during the late rise and plateau phases of the 2002 March–April outburst of the intermediate polar GK Per to determine that its X-ray pulse period P = 351.332 ± 0.002 s. Combined with previous X-ray and optical measurements of the spin period of the white dwarf, we find that its spin-up rate Ṗ = 0.00027 ± 0.00005 s yr−1.

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.

scholarly journals Timing Analysis with INTEGRAL: Comparing Different Reconstruction Algorithms

10.14311/1312 ◽  
2011 ◽  
Vol 51 (1) ◽  
Author(s):  
V. Grinberg ◽  
I. Kreykenbohm ◽  
F. Fürst ◽  
J. Wilms ◽  
K. Pottschmidt ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Time Resolution ◽  
Timing Analysis ◽  
Light Curves ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
X Ray ◽  
Coded Mask

INTEGRAL is one of the few instruments capable of detecting X-rays above 20 keV. It is therefore in principle well suited for studying X-ray variability in this regime. Because INTEGRAL uses coded mask instruments for imaging, the reconstruction of light curves of X-ray sources is highly non-trivial. We present results from a comparison of two commonly employed algorithms, which primarily measure flux from mask deconvolution (ii_lc_extract) and from calculating the pixel illuminated fraction (ii_light). Both methods agree well for timescales above about 10 s, the highest time resolution for which image reconstruction is possible. For higher time resolution, ii light produces meaningful results, although the overall variance of the lightcurves is not preserved.

scholarly journals Complex optical/UV and X-ray variability in Seyfert 1 galaxy Mrk 509

2021 ◽  
Vol 38 ◽  
Author(s):  
Neeraj Kumari ◽  
Main Pal ◽  
Sachindra Naik ◽  
Arghajit Jana ◽  
Gaurava K. Jaisawal ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Timing Analysis ◽  
Optical Emission ◽  
Light Curves ◽  
Thermal Component ◽  
X Ray ◽  
Uv Emission ◽  
Average Spectrum ◽  
Entire Duration ◽  
Using Data

Abstract We performed a detailed spectral and timing analysis of a Seyfert 1 galaxy Mrk 509 using data from the Neil Gehrels Swift observatory that spanned over $\sim$ 13 years between 2006 and 2019. To study the variability properties from the optical/UV to X-ray emission, we used a total of 275 pointed observations in this work. The average spectrum over the entire duration exhibits a strong soft X-ray excess above the power law continuum. The soft X-ray excess is well described by two thermal components with temperatures of kT $_{\rm BB1}\sim$ 120 eV and kT $_{\rm BB2}\sim$ 460 eV. The warm thermal component is likely due to the presence of an optically thick and warm Comptonizing plasma in the inner accretion disk. The fractional variability amplitude is found to be decreasing with increasing wavelength, i.e., from the soft X-ray to UV/optical emission. However, the hard X-ray (2–8 keV) emission shows very low variability. The strength of the correlation within the UV and the optical bands (0.95–0.99) is found to be stronger than the correlation between the UV/optical and X-ray bands (0.40–0.53). These results clearly suggest that the emitting regions of the X-ray and UV/optical emission are likely distinct or partly interacting. Having removed the slow variations in the light curves, we find that the lag spectrum is well described by the 4/3 rule for the standard Shakura–Sunyaev accretion disk when we omit X-ray lags. All these results suggest that the real disk is complex, and the UV emission is likely reprocessed in the accretion disk to give X-ray and optical emission.

scholarly journals Long-Term X-ray Variability of Circinus X-1 as Observed by the RXTE All Sky Monitor

2003 ◽  
Vol 214 ◽  
pp. 218-219
Author(s):  
Junfeng Wang ◽  
W. N. Brandt
Keyword(s):  
Timing Analysis ◽  
Period Change ◽  
Light Curves ◽  
Data Set ◽  
X Ray ◽  
Low Mass ◽  
Sky Monitor ◽  
Radio Band ◽  
Over Time

The luminous low mass X-ray binary Cir X-1 has been observed nearly continuously for about 5 years by the X-ray All Sky Monitor on board the RXTE satellite. We carried out a timing analysis on Cir X-1 with the RXTE data. We define the period from the X-ray data, comparing the period change over time with the best current ephemeris. with folded light curves of entire data set, characteristics of the system like long-term lightcurve changes, behavior of flares and dips and super-Eddington accretion were obtained. We also checked and identified the secondary flaring reported in radio band with X-ray data.

Structure of Zinc Phosphate Glasses of 75 and 80 mole% ZnO Content Studied by X-Ray Diffraction and Reverse Monte Carlo Simulations

2005 ◽  
Vol 60 (7) ◽  
pp. 517-526 ◽  
Author(s):  
Uwe Hoppe ◽  
Yanko Dimitriev ◽  
Pal Jóvári
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
High Energy ◽  
Phosphate Glasses ◽  
Strong Increase ◽  
Reverse Monte Carlo ◽  
X Ray Diffraction ◽  
X Ray ◽  
Coordination Numbers ◽  
Q Factors

X-Ray diffraction, using high-energy photons from a synchrotron, was used to extend the investigation of (ZnO)x(P2O5)1−x glasses to samples of ZnO content close to x = 0.8 which were obtained by roller-quenching. The isolated PO4 tetrahedra are surrounded by ZnOn polyhedra, where Zn−O coordination numbers of ∼ 4.5 are determined. The small increase of NZnO from ∼ 4 at metaphosphate composition (x = 0.5) to ∼ 4.5 is not sufficient to explain the strong increase of the packing density beyond the minimum at x = 0.5. The medium-range order was analyzed on the basis of partial SPP(Q) and SZnZn(Q) factors obtained from Reverse Monte Carlo simulations of glasses with 0 ≤ x ≤ 0.8. The positions of the first peaks in these factors, the number densities of P and Zn atoms and knowledge of definite P-P and Zn-Zn distances were used to check the applicability of simple models such as the dense packing of uniform P- and Zn-centered spherical environments for glasses with x=0.8 and 0.5, the packing of corrugated sheets for vitreous P2O5 and the packing of phosphate chains for Zn metaphosphate glass.

scholarly journals Supersoft X-Ray Source CAL 83: A Possible AE Aqr-like System

2015 ◽  
Vol 2 (1) ◽  
pp. 94-98 ◽  
Author(s):  
A. Odendaal ◽  
P. J. Meintjes ◽  
P. A. Charles ◽  
A. F. Rajoelimanana
Keyword(s):  
Timing Analysis ◽  
Rotation Period ◽  
Large Magellanic Cloud ◽  
Accretion Disc ◽  
Close Binary ◽  
X Rays ◽  
Hydrogen Burning ◽  
X Ray ◽  
Spin Period ◽  
Wing Structures

CAL83 is a close binary supersoft X-ray source in the Large Magellanic Cloud. A ~67 s periodicity detected in supersoft X-rays is most probably associated with the spin period of a highly spun-up white dwarf (WD). The variability in the period is ascribed to the obscuration of the WD by the hydrogen burning envelope surrounding it, rotating with a period that is close to, but not quite synchronized with, the WD rotation period. Optical spectra obtained with SALT exhibit accretion disc emission lines with broad wing structures and P Cyg profiles, indicating mass outflows. Timing analysis of photometrical observations performed at the South African Astronomical Observatory (SAAO) revealed variable signals at ≤1 mHz which are thought to be associated with quasi-periodic oscillations from an accretion disc. The short spin period inferred for CAL83 can be the result of spin-up by accretion disc torques during a long mass transfer history, placing this source on a similar evolutionary track as the cataclysmic variable AE Aqr.

scholarly journals The Magnetic Field of the Intermediate Polar RE 0751+14

1996 ◽  
Vol 158 ◽  
pp. 183-183
Author(s):  
H. Väth
Keyword(s):  
Magnetic Field ◽  
White Dwarf ◽  
Accretion Rate ◽  
Shock Structure ◽  
Light Curves ◽  
X Rays ◽  
Strong Magnetic Fields ◽  
X Ray ◽  
Spin Period ◽  
The Magnetic Field

Piirola, Hakala & Coyne (1993) modeled the optical/IR light curve of RE 0751+14 assuming a uniform shock structure and neglecting the hard X-ray emission. In this paper, we model the light curves at optical/IR and hard X-ray wavelengths and include the effects of the shock structure.We base our model on accretion onto a white dwarf with a displaced magnetic dipole for a range of likely white dwarf masses. We find that the observed intensity variations of X-rays and in the I band over one spin period largely determine the position of the emission regions. Furthermore, the observed maximum X-ray flux constrains the specific accretion rate. We deduce that the magnetic field at the pole is likely to be in the range 9 .. .21 MG, which is consistent with the estimates of Piirola et al. (1993). It had been proposed previously that there must exist asynchronous rotators with sufficiently strong magnetic fields such that the binaries will evolve into AM Her binaries (Chanmugam & Ray 1984; King, Frank & Ritter 1985). With this deduced high magnetic field RE 0751+14 is the most likely example of such a system known to date.

scholarly journals Outstanding X-ray emission from the stellar radio pulsar CU Virginis

2018 ◽  
Vol 619 ◽  
pp. A33 ◽  
Author(s):  
J. Robrade ◽  
L. M. Oskinova ◽  
J. H. M. M. Schmitt ◽  
P. Leto ◽  
C. Trigilio
Keyword(s):  
Spectral Component ◽  
High Energy ◽  
Light Curves ◽  
Magnetic Star ◽  
X Ray ◽  
Polarized Beams ◽  
Low Mass ◽  
Stellar Magnetospheres ◽  
Ap Stars ◽  
Component Models

Context. Among the intermediate-mass magnetic chemically peculiar (MCP) stars, CU Vir is one of the most intriguing objects. Its 100% circularly polarized beams of radio emission sweep the Earth as the star rotates, thereby making this strongly magnetic star the prototype of a class of nondegenerate stellar radio pulsars. While CU Vir is well studied in radio, its high-energy properties are not known. Yet, X-ray emission is expected from stellar magnetospheres and confined stellar winds. Aims. Using X-ray data we aim to test CU Vir for intrinsic X-ray emission and investigate mechanisms responsible for its generation. Methods. We present X-ray observations performed with XMM-Newton and Chandra and study obtained X-ray images, light curves, and spectra. Basic X-ray properties are derived from spectral modelling and are compared with model predictions. In this context we investigate potential thermal and nonthermal X-ray emission scenarios. Results. We detect an X-ray source at the position of CU Vir. With LX ≍ 3×1028 erg s−1 it is moderately X-ray bright, but the spectrum is extremely hard compared to other Ap stars. Spectral modelling requires multi-component models with predominant hot plasma at temperatures of about TX = 25 MK or, alternatively, a nonthermal spectral component. Both types of model provide a virtually equivalent description of the X-ray spectra. The Chandra observation was performed six years later than those by XMM-Newton, yet the source has similar X-ray flux and spectrum, suggesting a steady and persistent X-ray emission. This is further confirmed by the X-ray light curves that show only mild X-ray variability. Conclusions. CU Vir is also an exceptional star at X-ray energies. To explain its full X-ray properties, a generating mechanism beyond standard explanations, like the presence of a low-mass companion or magnetically confined wind-shocks, is required. Magnetospheric activity might be present or, as proposed for fast-rotating strongly magnetic Bp stars, the X-ray emission of CU Vir is predominantly auroral in nature.

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