scholarly journals Optical Light Curves of Luminous Eclipsing Black Hole X-Ray Binaries

2010 ◽  
Vol 62 (2) ◽  
pp. 467-474
Author(s):  
Ken-ya Watarai ◽  
Jun Fukue
Keyword(s):  
Black Hole ◽  
Light Curves ◽  
X Ray ◽  
X Ray Binaries

scholarly journals A minimal timescale for the continuum in 4U 1608-52 and Aql X-1

2021 ◽  
Vol 502 (1) ◽  
pp. L72-L78
Author(s):  
K Mohamed ◽  
E Sonbas ◽  
K S Dhuga ◽  
E Göğüş ◽  
A Tuncer ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Power Spectra ◽  
Light Curves ◽  
State Transitions ◽  
Strong Positive Correlation ◽  
Present Evidence ◽  
X Ray ◽  
X Ray Binaries ◽  
The Continuum

ABSTRACT Similar to black hole X-ray binary transients, hysteresis-like state transitions are also seen in some neutron-star X-ray binaries. Using a method based on wavelets and light curves constructed from archival Rossi X-ray Timing Explorer observations, we extract a minimal timescale over the complete range of transitions for 4U 1608-52 during the 2002 and 2007 outbursts and the 1999 and 2000 outbursts for Aql X-1. We present evidence for a strong positive correlation between this minimal timescale and a similar timescale extracted from the corresponding power spectra of these sources.

scholarly journals NuSTAR and Swift Observations of the Extragalactic Black Hole X-ray Binaries

2021 ◽  
Author(s):  
Arghajit Jana ◽  
Sachindra Naik ◽  
Debjit Chatterjee ◽  
Gaurava K Jaisawal
Keyword(s):  
Black Hole ◽  
Thermal Emission ◽  
Light Curves ◽  
Telescope Array ◽  
X Ray ◽  
Soft State ◽  
Galactic Black Hole ◽  
Photon Index ◽  
X Ray Binaries ◽  
Emission Fraction

Abstract We present the results obtained from detailed spectral and timing studies of extra-galactic black hole X-ray binaries LMC X–1 and LMC X–3, using simultaneous observations with Nuclear Spectroscopic Telescope Array (NuSTAR) and Neil Gehrels Swift observatories. The combined spectra in the 0.5 − 30 keV energy range, obtained between 2014 and 2019, are investigated for both sources. We do not find any noticeable variability in 0.5 − 30 keV light curves, with 0.1 − 10 Hz fractional rms estimated to be <2 per cent. No evidence of quasi-periodic oscillations is found in the power density spectra. The sources are found to be in the high soft state during the observations with disc temperature Tin ∼ 1 keV, photon index, Γ > 2.5 and thermal emission fraction, fdisc > 80 per cent. An Fe Kα emission line is detected in the spectra of LMC X–1, though no such feature is observed in the spectra of LMC X–3. From the spectral modelling, the spins of the black holes in LMC X–1 and LMC X–3 are estimated to be in the range of 0.92 − 0.95 and 0.19 − 0.29, respectively. The accretion efficiency is found to be, η ∼ 0.13 and η ∼ 0.04 for LMC X–1 and LMC X–3, respectively.

scholarly journals Optical, J and K light curves of XTE J1118+480 = KV UMa: the mass of the black hole and the spectrum of the non-stellar component

2019 ◽  
Vol 490 (3) ◽  
pp. 3287-3308 ◽  
Author(s):  
A M Cherepashchuk ◽  
N A Katysheva ◽  
T S Khruzina ◽  
S Yu Shugarov ◽  
A M Tatarnikov ◽  
...  
Keyword(s):  
Black Hole ◽  
Orientation Angle ◽  
Light Curves ◽  
Quiescent State ◽  
X Ray ◽  
Average Brightness ◽  
Photometric Observations ◽  
Stellar Component ◽  
Low Mass ◽  
X Ray Binaries

ABSTRACT Optical, J and K photometric observations of the KV UMa black hole X-ray nova in its quiescent state obtained in 2017–2018 are presented. A significant flickering within light curves was not detected, although the average brightness of the system faded by ≈0.1m over 350 d. Changes in the average brightness were not accompanied with an increase or decrease in the flickering. From the modelling of five light curves the inclination of the KV UMa orbit and the black hole mass were obtained: i = 74 ± 4°, $M_\mathrm{BH}=(7.06\rm {-}7.24)\, \mathrm{M}_{\odot }$, depending on the mass ratio used. The non-stellar component of the spectrum in the range λ = 6400–22 000 Å can be fitted by a power law Fλ ∼ λα, α ≈ −1.8. The accretion disc orientation angle changed from one epoch to another. The model with spots on the star was inadequate. Evolutionary calculations using the scenario machine code were performed for low-mass X-ray binaries, with a recently discovered anomalously rapid decrease of the orbital period taken into account. We show that the observed decrease can be consistent with the magnetic stellar wind of the optical companion, whose magnetic field was increased during the common-envelope stage. Several constraints on evolutionary scenario parameters were developed.

scholarly journals X-Ray Determination of the Black-Hole Mass in Cygnus X-1

1998 ◽  
Vol 188 ◽  
pp. 388-389
Author(s):  
A. Kubota ◽  
K. Makishima ◽  
T. Dotani ◽  
H. Inoue ◽  
K. Mitsuda ◽  
...  
Keyword(s):  
Black Hole ◽  
Compact Object ◽  
Optical Observations ◽  
Black Hole Mass ◽  
X Ray ◽  
Upper Limit ◽  
Supergiant Star ◽  
X Ray Binaries ◽  
Two Bodies

About 10 X-ray binaries in our Galaxy and LMC/SMC are considered to contain black hole candidates (BHCs). Among these objects, Cyg X-1 was identified as the first BHC, and it has led BHCs for more than 25 years(Oda 1977, Liang and Nolan 1984). It is a binary system composed of normal blue supergiant star and the X-ray emitting compact object. The orbital kinematics derived from optical observations indicates that the compact object is heavier than ~ 4.8 M⊙ (Herrero 1995), which well exceeds the upper limit mass for a neutron star(Kalogora 1996), where we assume the system consists of only two bodies. This has been the basis for BHC of Cyg X-1.

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 INTEGRAL view on black hole X-ray binaries

2021 ◽  
pp. 101618
Author(s):  
S.E. Motta ◽  
J. Rodriguez ◽  
E. Jourdain ◽  
M. Del Santo ◽  
G. Belanger ◽  
...  
Keyword(s):  
Black Hole ◽  
X Ray ◽  
X Ray Binaries
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