scholarly journals Investigating state transition luminosities of Galactic black hole transients in the outburst decay

2019 ◽  
Vol 485 (2) ◽  
pp. 2744-2758 ◽  
Author(s):  
A Vahdat Motlagh ◽  
E Kalemci ◽  
T J Maccarone
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Intermediate State ◽  
State Transition ◽  
Archival Data ◽  
Weighted Mean ◽  
X Ray ◽  
Galactic Black Hole ◽  
Photon Index ◽  
Hard State

Abstract We have performed a comprehensive spectral and timing analyses of Galactic black hole transients (GBHTs) during outburst decay in order to obtain the distribution of state transition luminosities. Using the archival data of the Rossi X-ray Timing Explorer (RXTE), we have calculated the weighted mean for state transition luminosities of 11 BH sources in 19 different outbursts and for disc and power law luminosities separately. We also produced histograms of these luminosities in terms of Eddington luminosity fraction (ELF) and fitted them with a Gaussian. Our results show the tightest clustering in bolometric power law luminosity with a mean logarithmic ELF of −1.70 ± 0.21 during the index transition (as the photon index starts to decrease towards the hard state). We obtained mean logarithmic ELF of −1.80 ± 0.25 during the transition to the hard state (as the photon index reaches the lowest value) and −1.50 ± 0.32 for disc-blackbody luminosity (DBB) during the transition to the hard-intermediate state (HIMS). We discussed the reasons for clustering and possible explanations for sources that show a transition luminosity significantly below or above the general trends.

scholarly journals Correlation of time lag and photon index in GX 339-4

2018 ◽  
Vol 614 ◽  
pp. L5 ◽  
Author(s):  
Nikolaos D. Kylafis ◽  
Pablo Reig
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Time Lag ◽  
Radio Spectrum ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Photon Index ◽  
Hard State ◽  
Two Parameters ◽  
Soft Disk

Context. Black hole transients, as a class, exhibit during their outbursts a correlation between the time lag of hard photons with respect to softer ones and the photon index of the hard X-ray power law. The correlation is not very tight and therefore it is necessary to examine it source by source. Aims. The objective of the present work is to investigate in detail the correlation between the time lag and the photon index in GX 339-4, which is the best studied black hole transient. Methods. We have obtained RXTE energy spectra and light curves and have computed the photon index and the time lag of the 9–15 keV photons with respect to the 2–6 keV photons. The observations cover the first stages of the hard state, the pure hard state, and the hard-intermediate state. Results. We have found a tight correlation between time lag and photon index Γ in the hard and hard-intermediate states. At low Γ, the correlation is positive; it becomes negative at high Γ By assuming that the hard X-ray power-law index Γ is produced by inverse Compton scattering of soft disk photons in the jet, we have reproduced the entire correlation by varying two parameters in the jet: the radius of the jet at its base R0 and the Thomson optical depth along the jet τ∥. We have found that as the luminosity of the source increases, R0 initially increases and then decreases. This behavior is expected in the context of the Cosmic Battery. Conclusions. Our jet model nicely explains the correlation with reasonable values of the parameters R0 and τ∥ These parameters also correlate between themselves. As a further test of our model, we predict the break frequency in the radio spectrum as a function of the photon index during the rising part of an outburst.

scholarly journals Long-term variability of Swift J1753.5−0127: X-ray spectral–temporal correlations during state transitions

2019 ◽  
Vol 487 (1) ◽  
pp. 1439-1446
Author(s):  
Qingcui Bu ◽  
Lian Tao ◽  
Yu Lu ◽  
Shuangnan Zhang ◽  
Liang Zhang ◽  
...  
Keyword(s):  
Black Hole ◽  
Intermediate State ◽  
State Transition ◽  
Time Lag ◽  
Periodic Oscillation ◽  
State Transitions ◽  
Time Lags ◽  
X Ray ◽  
Hard State

ABSTRACT We studied the long-term evolution of the spectral–temporal correlated properties of the black hole candidate Swift J1753.5−0127 from the onset of its outburst until 2011 with the Rossi X-ray Timing Explorer (RXTE). The source stayed most of its lifetime during hard state, with occasionally transitioned to the hard intermediate state. Similar to typical black hole transients, Swift J1753.5−0127 traces a clear hard line in absolute rms–intensity diagram during the low hard state, with expected highest absolute rms, while shows a clear turn during the hard intermediate state, accompanied by lower absolute rms. Different from Cyg X-1, we found that frequency-dependent time lag increased significantly in the 0.02–3.2 Hz band during state transition in this source. The X-ray time lags in 0.02–3.2 Hz can therefore be used as indicators of state transition in this source. Type-C quasi-periodic oscillation frequency is positively related with its fractional rms and X-ray photon index, suggesting a moving inwards disc/corona scenario. We discussed the physical interpretation of our results in this paper.

scholarly journals Energy and time-lag spectra of galactic black-hole X-ray sources in the low/hard state

2003 ◽  
Vol 403 (1) ◽  
pp. L15-L18 ◽  
Author(s):  
P. Reig ◽  
N. D. Kylafis ◽  
D. Giannios
Keyword(s):  
Black Hole ◽  
Time Lag ◽  
X Ray ◽  
Galactic Black Hole ◽  
Hard State

scholarly journals Discovery of a New X-ray Transient in Scorpius GRO J1655-40 ≡ X-ray Nova Scorpii 1994

1996 ◽  
Vol 165 ◽  
pp. 363-367
Author(s):  
W.S. Paciesas ◽  
S.N. Zhang ◽  
B.C. Rubin ◽  
B.A. Harmon ◽  
C.A. Wilson ◽  
...  
Keyword(s):  
Black Hole ◽  
High Resolution ◽  
Power Law ◽  
Radio Observations ◽  
X Ray ◽  
Black Hole Candidate ◽  
Radio Jets ◽  
Transient Source ◽  
Galactic Source ◽  
Photon Index

A bright transient X-ray source, GRO J1655-40 (X-ray Nova Scorpii 1994) was discovered with BATSE (the Burst and Transient Source Experiment) in late July 1994. More recently, the source also became a strong radio emitter, its rise in the radio being approximately anti-correlated with a decline in the hard X-ray intensity. High-resolution radio observations subsequent to this symposium showed evidence for superluminally expanding jets. Since the hard X-ray emission extends to at least 200 keV and we find no evidence of pulsations, we tentatively classify the source as a black-hole candidate. However, its hard X-ray spectrum is unusually steep (power-law photon index α ≃ −3) relative to most other black-hole candidates. In this regard, it resembles GRS 1915+105, the first galactic source to show superluminal radio jets.

scholarly journals Inclination effects on the X-ray emission of Galactic black-hole binaries

2019 ◽  
Vol 625 ◽  
pp. A90 ◽  
Author(s):  
Pablo Reig ◽  
Nikolaos D. Kylafis
Keyword(s):  
Black Hole ◽  
Linear Regression Analysis ◽  
Time Lag ◽  
Light Curves ◽  
Energy Spectra ◽  
Time Lags ◽  
X Ray ◽  
Galactic Black Hole ◽  
Photon Index ◽  
Inclination Angles

Context. Galactic black-hole X-ray binaries (BHBs) emit a compact, optically thick, mildly relativistic radio jet when they are in hard and hard-intermediate states. In these states, BHBs exhibit a correlation between the time lag of hard with respect to softer photons and the photon index of the power law component that characterizes the X-ray spectral continuum above ∼10 keV. The correlation, however, shows large scatter. In recent years, several works have brought to light the importance of taking into account the inclination of the systems to understand the X-ray and radio phenomenology of BHBs. Aims. Our objective is to investigate the role that the inclination plays on the correlation between the time lag and photon index. Methods. We obtained RXTE energy spectra and light curves of a sample of BHBs with different inclination angles. We computed the photon index and the time lag between hard and soft photons and performed a correlation and linear regression analysis of the two variables. We also computed energy spectra and light curves of BHBs using the Monte Carlo technique that reproduces the process of Comptonization in the jet. We account for the inclination effects by recording the photons that escape from the jet at different angles. From the simulated light curves and spectra we obtained model-dependent photon index and time lags, which we compared with those obtained from the real data. Results. We find that the correlation between the time lag and photon index is tight in low-inclination systems and becomes weaker in high-inclination systems. The amplitude of the lags is also larger at low- and intermediate-inclination angles than at high inclination. We also find that the photon index and time lag, obtained from the simulated spectra and light curves, also follow different relationships for different inclination angle ranges. Our jet model reproduces the observations remarkably well. The same set of models that reproduces the correlation for the low-inclination systems, also accounts for the correlation for intermediate- and high-inclination systems fairly well. Conclusions. The large dispersion observed in the time lag – photon index correlation in BHBs can naturally be explained as an inclination effect. Comptonization in the jet explains the steeper dependence of the lags on the photon index in low- and intermediate-inclination systems than in high-inclination systems.

scholarly journals A Study on the Hysteresis Effect and Spectral Evolution in the Mini-Outbursts of Black Hole X-Ray Binary XTE J1550-564

2021 ◽  
Vol 8 ◽  
Author(s):  
Ai-Jun Dong ◽  
Chang Liu ◽  
Kang Ge ◽  
Xiang Liu ◽  
Qi-Jun Zhi ◽  
...  
Keyword(s):  
Black Hole ◽  
State Transition ◽  
Hysteresis Effect ◽  
Transition Model ◽  
Spectral Evolution ◽  
X Ray ◽  
Photon Count ◽  
Hard State ◽  
State Transition Model ◽  
Spectral State

One normal outburst and three mini-outbursts have been detected by Rossi X-ray Timing Explorer satellite after 2000 in the well-known black hole X-ray binary XTE J1550-564. In this work, we explore the hysteresis effect of the four outbursts, which is a phenomenon that a similar spectral state transition occurs at different luminosity in an outburst of black hole X-ray binary. A q-like track was found in the hardness-intensity diagram of the normal outburst in 2000 but not in the three mini-outbursts that only occur in the Low/Hard state. The results demonstrate that the hysteresis effect is not apparent in the three mini-outbursts and the X-ray spectra are harder than that of the normal outburst at the same photon count rate. Furthermore, the results of the correlation analysis show that the Γ − F2−10keV correlation of mini-outburst maintain negative in the Low/Hard state with the harder spectra than that of the normal outburst at the same X-ray flux. The X-ray spectral evolution can be well-explained by the state-transition model from the Shakura–Sunyaev disk to the advection-dominated accretion flow, which implies that the three mini-outbursts of XTE J1550-564 might originate from a smaller discrete accretion event.

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 Spectra and time variability of Galactic black-hole X-ray sources in the low/hard state

2004 ◽  
Vol 425 (1) ◽  
pp. 163-169 ◽  
Author(s):  
D. Giannios ◽  
N. D. Kylafis ◽  
D. Psaltis
Keyword(s):  
Black Hole ◽  
Time Variability ◽  
X Ray ◽  
Galactic Black Hole ◽  
Hard State

scholarly journals The causal connection between disc and power-law variability in hard state black hole X-ray binaries

2011 ◽  
Vol 414 (1) ◽  
pp. L60-L64 ◽  
Author(s):  
P. Uttley ◽  
T. Wilkinson ◽  
P. Cassatella ◽  
J. Wilms ◽  
K. Pottschmidt ◽  
...  
Keyword(s):  
Black Hole ◽  
Power Law ◽  
Causal Connection ◽  
X Ray ◽  
Hard State ◽  
X Ray Binaries

scholarly journals Isolating the jet in broadband spectra of XBs

2010 ◽  
Vol 6 (S275) ◽  
pp. 317-318
Author(s):  
David M. Russell ◽  
Fraser Lewis ◽  
Dipankar Maitra ◽  
Robert J. H. Dunn ◽  
Sera Markoff ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Power Law ◽  
Spectral Energy ◽  
Synchrotron Emission ◽  
Energy Distributions ◽  
X Ray ◽  
Relativistic Jet ◽  
Hard State ◽  
X Ray Binaries

AbstractMost accretion-powered relativistic jet sources in our Galaxy are transient X-ray binaries (XBs). Efforts to coordinate multiwavelength observations of these objects have improved dramatically over the last decade. Now the challenge is to interpret broadband spectral energy distributions (SEDs) of XBs that are well sampled in both wavelength and time. Here we focus on the evolution of the jet in their broadband spectra. Some of the most densely sampled broadband SEDs of a neutron star transient (IGR J00291+5934) are used to constrain the optically thick–thin break in the jet spectrum. For the black hole transient XTE J1550-564, infrared – X-ray correlations, evolution of broadband spectra and timing signatures indicate that synchrotron emission from the jet likely dominates the X-ray power law at low luminosities (~(2 × 10−4 − 2 × 10−3) LEdd) during the hard state outburst decline.

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