scholarly journals Models for the Observable System Parameters of Ultraluminous X‐Ray Sources

2008 ◽  
Vol 688 (2) ◽  
pp. 1235-1249 ◽  
Author(s):  
N. Madhusudhan ◽  
S. Rappaport ◽  
Ph. Podsiadlowski ◽  
L. Nelson
Keyword(s):  
X Ray ◽  
System Parameters ◽  
Observable System

scholarly journals The frequency of Kozai–Lidov disc oscillation driven giant outbursts in Be/X-ray binaries

2019 ◽  
Vol 489 (2) ◽  
pp. 1797-1804 ◽  
Author(s):  
Rebecca G Martin ◽  
Alessia Franchini
Keyword(s):  
Orbital Period ◽  
Time Scale ◽  
Orbital Plane ◽  
Material Flows ◽  
X Ray ◽  
System Parameters ◽  
Be Star ◽  
Chaotic Nature ◽  
X Ray Binaries ◽  
Good Agreement

ABSTRACT Giant outbursts of Be/X-ray binaries may occur when a Be-star disc undergoes strong eccentricity growth due to the Kozai–Lidov (KL) mechanism. The KL effect acts on a disc that is highly inclined to the binary orbital plane provided that the disc aspect ratio is sufficiently small. The eccentric disc overflows its Roche lobe and material flows from the Be star disc over to the companion neutron star causing X-ray activity. With N-body simulations and steady state decretion disc models we explore system parameters for which a disc in the Be/X-ray binary 4U 0115+634 is KL unstable and the resulting time-scale for the oscillations. We find good agreement between predictions of the model and the observed giant outburst time-scale provided that the disc is not completely destroyed by the outburst. This allows the outer disc to be replenished between outbursts and a sufficiently short KL oscillation time-scale. An initially eccentric disc has a shorter KL oscillation time-scale compared to an initially circular orbit disc. We suggest that the chaotic nature of the outbursts is caused by the sensitivity of the mechanism to the distribution of material within the disc. The outbursts continue provided that the Be star supplies material that is sufficiently misaligned to the binary orbital plane. We generalize our results to Be/X-ray binaries with varying orbital period and find that if the Be star disc is flared, it is more likely to be unstable to KL oscillations in a smaller orbital period binary, in agreement with observations.

scholarly journals A tale of two periods: determination of the orbital ephemeris of the super-Eddington pulsar NGC 7793 P13

2018 ◽  
Vol 616 ◽  
pp. A186 ◽  
Author(s):  
F. Fürst ◽  
D. J. Walton ◽  
M. Heida ◽  
F. A. Harrison ◽  
D. Barret ◽  
...  
Keyword(s):  
Accretion Disk ◽  
Orbital Period ◽  
Timing Analysis ◽  
X Ray ◽  
System Parameters ◽  
Orbital Resonance ◽  
Photometric Period ◽  
Orbital Periods ◽  
Analyze Data

We present a timing analysis of multiple XMM-Newton and NuSTAR observations of the ultra-luminous pulsar NGC 7793 P13 spread over its 65 d variability period. We use the measured pulse periods to determine the orbital ephemeris, confirm a long orbital period with Porb = 63.9+0.5−0.6 d, and find an eccentricity of e ≤ 0.15. The orbital signature is imprinted on top of a secular spin-up, which seems to get faster as the source becomes brighter. We also analyze data from dense monitoring of the source with Swift and find an optical photometric period of 63.9 ± 0.5 d and an X-ray flux period of 66.8 ± 0.4 d. The optical period is consistent with the orbital period, while the X-ray flux period is significantly longer. We discuss possible reasons for this discrepancy, which could be due to a super-orbital period caused by a precessing accretion disk or an orbital resonance. We put the orbital period of P13 into context with the orbital periods implied for two other ultra-luminous pulsars, M82 X-2 and NGC 5907 ULX, and discuss possible implications for the system parameters.

scholarly journals The 2016 super-Eddington outburst of SMC X-3: X-ray and optical properties and system parameters

2017 ◽  
Vol 471 (4) ◽  
pp. 3878-3887 ◽  
Author(s):  
L. J. Townsend ◽  
J. A. Kennea ◽  
M. J. Coe ◽  
V. A. McBride ◽  
D. A. H. Buckley ◽  
...  
Keyword(s):  
Optical Properties ◽  
X Ray ◽  
System Parameters

A Feasibility Study of Using X-Ray Computer Tomography for Ball Grid Array (BGA) Inspection

2008 ◽  
Vol 594 ◽  
pp. 331-338 ◽  
Author(s):  
Shin Chieh Lin ◽  
Hsin I Lu
Keyword(s):  
Feasibility Study ◽  
Computer Tomography ◽  
Ball Grid Array ◽  
Reconstructed Image ◽  
Simulation Test ◽  
X Ray ◽  
System Parameters ◽  
Beam Projection ◽  
Sensor Geometry

It is of interest to study the feasibility of using computing tomography technique on BGA inspection. The effects of system parameters on the quality of the reconstructed images were studied first. The system parameters studied are projection type, projection number, sensor number, and filter. For fan beam projection, there are two additional parameters are studied. They are the fan beam arc angle and the sensor geometry. It was found that the increase in projection number and sensor number generally improve the quality of reconstructed image. The effects of sensor geometry and the fan beam arc angle are not significant. BGA simulation test show the feasibility of using this technique to detect the shape and location of defects inside the BGA.

scholarly journals Six Supersoft X‐Ray Binaries: System Parameters and Twin‐Jet Outflows

1998 ◽  
Vol 504 (2) ◽  
pp. 854-865 ◽  
Author(s):  
A. P. Cowley ◽  
P. C. Schmidtke ◽  
David Crampton ◽  
J. B. Hutchings
Keyword(s):  
X Ray ◽  
System Parameters ◽  
X Ray Binaries

scholarly journals Orbital and superorbital monitoring of the Be/X-ray binary A0538–66: constraints on the system parameters

2016 ◽  
Vol 464 (4) ◽  
pp. 4133-4144 ◽  
Author(s):  
A. F. Rajoelimanana ◽  
P. A. Charles ◽  
P. J. Meintjes ◽  
L. J. Townsend ◽  
M. P. E. Schurch ◽  
...  
Keyword(s):  
X Ray ◽  
System Parameters

scholarly journals X-Ray Fluorescence Experiments with Polarized X-Rays*

1974 ◽  
Vol 18 ◽  
pp. 265-277 ◽  
Author(s):  
R. H. Howell ◽  
W. L. Pickles ◽  
J. L. Cate
Keyword(s):  
Compton Scattering ◽  
Usual Method ◽  
X Rays ◽  
Scattering System ◽  
X Ray ◽  
System Parameters ◽  
Preliminary Results ◽  
Geometric Limit ◽  
Solid Angles ◽  
Approximate Expressions

AbstractTwo methods of obtaining polarized x-rays for fluorescence experiments are discussed. Compton scattering from a low-Z scatterer is the usual method used in such experiments. The polarization of x-rays undergoing anomalous Borrmann transmission in a dislocation-free crystal is also described and preliminary results are presented. Approximate expressions, useful for comparing scatter-polarizing systems, are derived for the dependence of scatter rejection and fluorescent efficiency on two scattering-system parameters: the thickness of the scattering polarizer and the geometric limit to solid angles and angular divergences in the system.

scholarly journals A MeerKAT survey of nearby nova-like cataclysmic variables

2020 ◽  
Vol 496 (3) ◽  
pp. 2542-2557 ◽  
Author(s):  
D M Hewitt ◽  
M L Pretorius ◽  
P A Woudt ◽  
E Tremou ◽  
J C A Miller-Jones ◽  
...  
Keyword(s):  
Radio Emission ◽  
Cataclysmic Variables ◽  
Spectral Energy ◽  
Energy Distributions ◽  
Transfer Rates ◽  
X Ray ◽  
System Parameters ◽  
Radio Detection ◽  
Low Mass ◽  
X Ray Binaries

ABSTRACT We present the results of MeerKAT radio observations of 11 nearby nova-like cataclysmic variables (CVs). We have detected radio emission from IM Eri, RW Sex, V3885 Sgr, and V603 Aql. While RW Sex, V3885 Sgr, and V603 Aql had been previously detected, this is the first reported radio detection of IM Eri. Our observations have doubled the sample of non-magnetic CVs with sensitive radio data. We observe that at our radio detection limits, a specific optical luminosity ${\gtrsim}2.2\times 10^{18}\,$ erg s−1 Hz−1 (corresponding to MV ≲ 6.0) is required to produce a radio detection. We also observe that the X-ray and radio luminosities of our detected nova-like CVs are on an extension of the $L_X\propto L_R^{\sim 0.7}$ power law originally proposed for non-pulsating neutron star low-mass X-ray binaries. We find no other correlations between the radio emission and emission in other wavebands or any other system parameters for the existing sample of radio-detected non-magnetic CVs. We measure in-band (0.9–1.7 GHz) radio spectral indices that are consistent with reports from earlier work. Finally, we constructed broad spectral energy distributions for our sample from published multiwavelength data, and use them to place constraints on the mass transfer rates of these systems.

scholarly journals The Kepler-11 system: evolution of the stellar high-energy emission and initial planetary atmospheric mass fractions

2019 ◽  
Vol 632 ◽  
pp. A65 ◽  
Author(s):  
D. Kubyshkina ◽  
L. Fossati ◽  
A. J. Mustill ◽  
P. E. Cubillos ◽  
M. B. Davies ◽  
...  
Keyword(s):  
Mass Loss ◽  
Extreme Ultraviolet ◽  
High Energy ◽  
X Ray ◽  
System Parameters ◽  
The Past ◽  
Energy Emission ◽  
Mass Fractions ◽  
High Energy Emission ◽  
Atmospheric Mass

The atmospheres of close-in planets are strongly influenced by mass loss driven by the high-energy (X-ray and extreme ultraviolet, EUV) irradiation of the host star, particularly during the early stages of evolution. We recently developed a framework to exploit this connection and enable us to recover the past evolution of the stellar high-energy emission from the present-day properties of its planets, if the latter retain some remnants of their primordial hydrogen-dominated atmospheres. Furthermore, the framework can also provide constraints on planetary initial atmospheric mass fractions. The constraints on the output parameters improve when more planets can be simultaneously analysed. This makes the Kepler-11 system, which hosts six planets with bulk densities between 0.66 and 2.45 g cm−3, an ideal target. Our results indicate that the star has likely evolved as a slow rotator (slower than 85% of the stars with similar masses), corresponding to a high-energy emission at 150 Myr of between 1 and 10 times that of the current Sun. We also constrain the initial atmospheric mass fractions for the planets, obtaining a lower limit of 4.1% for planet c, a range of 3.7–5.3% for planet d, a range of 11.1–14% for planet e, a range of 1–15.6% for planet f, and a range of 4.7–8.7% for planet g assuming a disc dispersal time of 1 Myr. For planet b, the range remains poorly constrained. Our framework also suggests slightly higher masses for planets b, c, and f than have been suggested based on transit timing variation measurements. We coupled our results with published planet atmosphere accretion models to obtain a temperature (at 0.25 AU, the location of planet f) and dispersal time of the protoplanetary disc of 550 K and 1 Myr, although these results may be affected by inconsistencies in the adopted system parameters. This work shows that our framework is capable of constraining important properties of planet formation models.

Sign in / Sign up

Export Citation Format

Share Document