scholarly journals Millisecond Time Variations of X-Ray Binaries

1998 ◽  
Vol 188 ◽  
pp. 107-110
Author(s):  
J. H. Swank
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Beat Frequency ◽  
Rotation Period ◽  
Periodic Oscillation ◽  
Frequency Model ◽  
X Ray ◽  
Low Mass ◽  
The Difference ◽  
X Ray Binaries

Millisecond time-scales are natural for some neutron star and black hole processes, although possibly difficult to observe. The Rossi X-Ray Timing Explorer (RXTE) has found that for the neutron stars in low-mass X-ray binaries (LMXB) there are flux oscillations at high frequencies, with large amplitudes. Z sources and bursters tend to exhibit oscillations in the range 300-1200 Hz. Persistent emission may exhibit one or both of two features. In bursts from different bursters, a nearly coherent pulsation is seen, which may be the rotation period of the neutron star. For some the frequency equals the difference between the two higher frequencies, suggesting a beat frequency model, but in others it is twice the difference. The sources span two orders of magnitude in accretion rate, yet the properties are similar. The similar maximum frequencies suggests that it corresponds to the Kepler orbit frequency at the minimum stable orbit or the neutron star surface, either of which would determine the neutron star masses, radii and equation of state. Theories of accretion onto black holes predict a quasi-periodic oscillation (QPO) related to the inner accretion disk. The two microquasar black hole candidates (BHCs) have exhibited candidates for this or related frequencies.

scholarly journals The Beat Frequency Model for QPOs

1987 ◽  
Vol 125 ◽  
pp. 347-361 ◽  
Author(s):  
Jacob Shaham
Keyword(s):  
Beat Frequency ◽  
Periodic Oscillation ◽  
The Other ◽  
Prime Model ◽  
Single Model ◽  
Frequency Model ◽  
Quasi Periodic Oscillation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

We have to date reports of Quasi-Periodic-Oscillation (QPO) observations in some twelve X-ray source, of which at least seven are low mass X-ray binaries (van der Klis 1987). They constitute a formidable zoo of phenomenae with so much variety that they, at times, do not at all even seem amenable to a single model. Some of the other QPO talks in these proceedings will try and present observations in the context of various models. My task is to talk about the Beat Frequency Model which, it seems to me, is by far the prime model for at least some of the QPOs.

scholarly journals Kilohertz QPO in Low Mass X-Ray Binaries: an Overview

1997 ◽  
Vol 163 ◽  
pp. 347-350
Author(s):  
M. van der Klis
Keyword(s):  
Beat Frequency ◽  
Current Status ◽  
Frequency Model ◽  
Periodic Oscillations ◽  
Simple Interpretation ◽  
X Ray ◽  
Peak Separation ◽  
Low Mass ◽  
The Difference ◽  
X Ray Binaries

AbstractI review the current status of the investigations of the kilohertz quasi-periodic oscillations that have been discovered in low-mass Xray binaries (LMXBs) with NASA’s Rossi X-ray Timing Explorer (RXTE) since February 1996. Seven sources have now shown this new phenomenon, one Z source (Sco X–l) and 6 atoll sources (all X-ray bursters), and some patterns are beginning to emerge. The frequencies of the oscillations are between 500 and 1200 Hz. They can be coherent for more than 102 cycles, but a more typical coherence is several 101. Amplitudes are between 0.5 and 16% (rms) of the total flux. Most sources show double kHz peaks separated by a few 102 Hz, which move up and down in frequency together. In Sco X–l the peak frequencies systematically increase, and the peak separation systematically decreases, with Ṁ. In 4U 1728–34 a third oscillation is seen at a frequency equal to the difference frequency of the two kHz peaks, but only during X-ray bursts. A simple interpretation in terms of a beat-frequency model with the difference frequency being the neutron star’s spin, as suggested by this result, is inconsistent with the fact that in Sco X–l the peak separation varies.

scholarly journals A Machine Learning Approach For Classifying Low-mass X-ray Binaries Based On Their Compact Object Nature

2020 ◽  
Author(s):  
R Pattnaik ◽  
K Sharma ◽  
K Alabarta ◽  
D Altamirano ◽  
M Chakraborty ◽  
...  
Keyword(s):  
Machine Learning ◽  
Black Hole ◽  
Neutron Star ◽  
Binary Systems ◽  
Compact Object ◽  
X Ray ◽  
Average Accuracy ◽  
Machine Learning Approach ◽  
Low Mass ◽  
X Ray Binaries

Abstract Low Mass X-ray binaries (LMXBs) are binary systems where one of the components is either a black hole or a neutron star and the other is a less massive star. It is challenging to unambiguously determine whether a LMXB hosts a black hole or a neutron star. In the last few decades, multiple observational works have tried, with different levels of success, to address this problem. In this paper, we explore the use of machine learning to tackle this observational challenge. We train a random forest classifier to identify the type of compact object using the energy spectrum in the energy range 5-25 keV obtained from the Rossi X-ray Timing Explorer archive. We report an average accuracy of 87±13% in classifying the spectra of LMXB sources. We further use the trained model for predicting the classes for LMXB systems with unknown or ambiguous classification. With the ever-increasing volume of astronomical data in the X-ray domain from present and upcoming missions (e.g., SWIFT, XMM-Newton, XARM, ATHENA, NICER), such methods can be extremely useful for faster and robust classification of X-ray sources and can also be deployed as part of the data reduction pipeline.

scholarly journals The Beat-Frequency Interpretation of Kilohertz Quasi-periodic Oscillations in Neutron Star Low-Mass X-Ray Binaries

1998 ◽  
Vol 501 (1) ◽  
pp. L95-L99 ◽  
Author(s):  
Dimitrios Psaltis ◽  
Mariano Méndez ◽  
Rudy Wijnands ◽  
Jeroen Homan ◽  
Peter G. Jonker ◽  
...  
Keyword(s):  
Neutron Star ◽  
Beat Frequency ◽  
Periodic Oscillations ◽  
X Ray ◽  
Frequency Interpretation ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals Formation of Low-Mass Black Hole X-Ray Transients

1998 ◽  
Vol 11 (2) ◽  
pp. 775-778
Author(s):  
Simon Portegies Zwart ◽  
Frank Verbunt ◽  
Ene Ergma
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
Formation Rate ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

We study the formation of low-mass X-ray binaries with a black hole as accreting object. The performed semi-analytic analysis reveals that the formation rate of black holes in low-mass X-ray binaries is about two orders of magnitude smaller than that of systems with a neutron star as accretor. This is contradicted by the six observed systems, which are all transients, which suggest that the majority of these systems has not been seen jet. The birthrate for both type of objects are expected to be similar (for reviews see Cowley 1992, Tanaka & Lewin 1995).

scholarly journals Black hole-like hysteresis and accretion states in neutron star low-mass X-ray binaries

2014 ◽  
Vol 443 (4) ◽  
pp. 3270-3283 ◽  
Author(s):  
T. Muñoz-Darias ◽  
R. P. Fender ◽  
S. E. Motta ◽  
T. M. Belloni
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals The Formation and Evolution of Black-Hole Binaries

1996 ◽  
Vol 165 ◽  
pp. 93-103
Author(s):  
Roger W. Romani
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
High Mass ◽  
X Ray ◽  
Black Hole Binaries ◽  
Low Mass ◽  
Formation And Evolution ◽  
X Ray Binaries ◽  
Black Hole Candidates

The presence of accreting black holes (BH) among the X-ray binaries has been recognized for many years. Traditionally, Cyg X-1 and the handful of other candidates have been thought of as cousins of the HMXB neutron star systems. Recent studies of the soft X-ray transients such as A 0620-00 have, however, shown that the dynamical evidence makes these low-mass systems very strong black-hole candidates. Further, analysis of the eventual end-states of various high-mass X-ray binaries suggest that some could end as observable BH-pulsar binaries, although the first such system is yet to be discovered.

scholarly journals Variability of winds in X-ray binaries

2012 ◽  
Vol 8 (S290) ◽  
pp. 25-28
Author(s):  
M. Díaz Trigo ◽  
L. Boirin ◽  
S. Migliari ◽  
J. Miller-Jones ◽  
A. Parmar ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Column Density ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries ◽  
The Continuum

AbstractWe discuss the variability of winds in two low-mass X-ray binaries, GX 13+1 and 4U 1630-47. XMM-Newton observations of these sources show that strong, photoionised winds with column densities well above 1022 cm−2 can be present in both neutron star and black hole LMXBs. Such winds can fade significantly due to changes in the flux or spectral hardness of the continuum. In particular, a decrease of column density and/or an increase of ionisation are measured when the flux increases or the spectrum hardens. We show how variability studies can help us to understand what triggers changes in the wind and discuss the limitations of current instruments for such studies.

scholarly journals Measuring the Masses of Compact Objects in Low-Mass X-Ray Binaries

2004 ◽  
Vol 194 ◽  
pp. 214-214
Author(s):  
Dawn M. Gelino
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Compact Object ◽  
Compact Objects ◽  
Orbital Inclination ◽  
X Ray ◽  
Secondary Star ◽  
Low Mass ◽  
The Masses ◽  
X Ray Binaries

Low-mass X-ray binaries (LMXBs) contain compact, black hole (BH) or neutron star (NS) primaries, and cool, low-mass secondary stars. We measure the orbital inclination of the system in quiescence by modeling infrared (IR) ellipsoidal variations from the secondary star in order to determine the compact object mass. I present our results for a few LMXBs, including the first BH that appears to conclusively fall in the 3-5 M⊙ range.

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