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

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.

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

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935070 ◽

2019 ◽

Vol 625 ◽

pp. A90 ◽

Cited By ~ 4

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.

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

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slab004 ◽

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.

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The soft state of the black hole transient source MAXI J1820+070: emission from the edge of the plunge region?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa564 ◽

2020 ◽

Vol 493 (4) ◽

pp. 5389-5396 ◽

Cited By ~ 5

Author(s):

A C Fabian ◽

D J Buisson ◽

P Kosec ◽

C S Reynolds ◽

D R Wilkins ◽

...

Keyword(s):

Black Hole ◽

Photon Counting ◽

Black Hole Mass ◽

X Ray ◽

Excess Emission ◽

Transient Source ◽

Stable Circular Orbit ◽

Soft State ◽

Galactic Black Hole ◽

Innermost Stable Circular Orbit

ABSTRACT The Galactic black hole X-ray binary MAXI J1820+070 had a bright outburst in 2018 when it became the second brightest X-ray source in the sky. It was too bright for X-ray CCD instruments such as XMM–Newton and Chandra, but was well observed by photon-counting instruments such as Neutron star Inner Composition Explorer (NICER) and Nuclear Spectroscopic Telescope Array(NuSTAR). We report here on the discovery of an excess-emission component during the soft state. It is best modelled with a blackbody spectrum in addition to the regular disc emission, modelled as either diskbb or kerrbb. Its temperature varies from about 0.9 to 1.1 keV, which is about 30–80 per cent higher than the inner disc temperature of diskbb. Its flux varies between 4 and 12 per cent of the disc flux. Simulations of magnetized accretion discs have predicted the possibility of excess emission associated with a non-zero torque at the innermost stable circular orbit (ISCO) about the black hole, which, from other NuSTAR studies, lies at about 5 gravitational radii or about 60 km (for a black hole, mass is $8\, {\rm M}_{\odot }$). In this case, the emitting region at the ISCO has a width varying between 1.3 and 4.6 km and would encompass the start of the plunge region where matter begins to fall freely into the black hole.

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Correlation between the photon index and X-ray luminosity of black hole X-ray binaries and active galactic nuclei: observations and interpretation

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stu2571 ◽

2014 ◽

Vol 447 (2) ◽

pp. 1692-1704 ◽

Cited By ~ 56

Author(s):

Qi-Xiang Yang ◽

Fu-Guo Xie ◽

Feng Yuan ◽

Andrzej A. Zdziarski ◽

Marek Gierliński ◽

...

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

X Ray ◽

Photon Index ◽

X Ray Binaries

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Near-Eddington Luminosity Flares from Quiescent Supermassive Black Holes

Proceedings of the International Astronomical Union ◽

10.1017/s174392131000654x ◽

2009 ◽

Vol 5 (S267) ◽

pp. 319-324

Author(s):

Suvi Gezari

Keyword(s):

Black Hole ◽

Thermal Emission ◽

Rare Event ◽

Light Curves ◽

Spectral Energy ◽

Wide Field ◽

Tidal Disruption ◽

X Ray ◽

Solar Type ◽

Detection Capabilities

AbstractA dormant supermassive black hole lurking in the center of a galaxy will be revealed when a star passes within its tidal disruption radius, is disrupted, and a flare of electromagnetic radiation is emitted when the bound stellar debris is accreted. Although the tidal disruption of a star is a rare event in a galaxy, ~ 10−4 yr−1, observational candidates have emerged in all-sky X-ray and deep UV surveys in the form of luminous UV/X-ray flares from otherwise quiescent galaxies. We present the light curves and broadband properties of three tidal disruption candidates discovered in the UV by GALEX, and find that (1) the light curves are well-fitted by the power-law decline expected for the fallback of debris from a tidally disrupted solar-type star, and (2) the UV/optical spectral energy distributions can be attributed to thermal emission from an envelope of debris located at ten times the tidal disruption radius of the central black hole. We use the observed peak absolute optical magnitudes of the flares to predict the detection capabilities of the next generation of wide-field optical synoptic surveys.

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Properties of the two-temperature corona model for active galactic nuclei and galactic black hole X-ray Binaries

New Astronomy ◽

10.1016/s1384-1076(99)00051-2 ◽

2000 ◽

Vol 5 (1) ◽

pp. 7-24 ◽

Cited By ~ 18

Author(s):

Agnieszka Janiuk ◽

Bożena Czerny

Keyword(s):

Black Hole ◽

Active Galactic Nuclei ◽

Galactic Nuclei ◽

X Ray ◽

Galactic Black Hole ◽

X Ray Binaries ◽

Two Temperature

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Multiwavelength analysis as a probe of accretion and radiative processes in LINERs

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312020388 ◽

2012 ◽

Vol 8 (S290) ◽

pp. 355-356

Author(s):

George Younes ◽

Delphine Porquet

Keyword(s):

Black Hole ◽

Energy Distribution ◽

Spectral Energy Distribution ◽

Spectral Characteristics ◽

Spectral Energy ◽

X Ray ◽

Radiative Processes ◽

Central Engine ◽

Galactic Black Hole ◽

X Ray Binaries

AbstractWe study the multiwavelength properties of an optically selected sample of Low Ionization Nuclear Emission-line Regions (LINERs), in an attempt to determine the accretion mechanism powering their central engine. We show how their X-ray spectral characteristics, and their spectral energy distribution compare to luminous AGN, and briefly discuss their connection to their less massive counter-parts galactic black-hole X-ray binaries.

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