AstroSat and MAXI view of the black hole binary 4U 1630−472 during 2016 and 2018 outbursts

ABSTRACT We present an in-depth spectral and timing analysis of the black hole binary 4U 1630−472 during 2016 and 2018 outbursts as observed by AstroSat and MAXI. The extensive coverage of the outbursts with MAXI is used to obtain the hardness intensity diagram (HID). The source follows a ‘c’-shaped profile in agreement with earlier findings. Based on the HIDs of previous outbursts, we attempt to track the evolution of the source during a ‘super’-outburst and ‘mini’-outbursts. We model the broad-band energy spectra (0.7–20.0 keV) of AstroSat observations of both outbursts using phenomenological and physical models. No Keplerian disc signature is observed at the beginning of 2016 outburst. However, the disc appears within a few hours after which it remains prominent with temperature (Tin) ∼ 1.3 keV and increase in photon index (Γ) from 1.8 to 2.0, whereas the source was at a disc dominant state throughout the AstroSat campaign of 2018 outburst. Based on the HIDs and spectral properties, we classify the outbursts into three different states – the ‘canonical’ hard and soft states along with an intermediate state. Evolution of rms along different states is seen although no quasi-periodic oscillations are detected. We fit the observed spectra using a dynamical accretion model and estimate the accretion parameters. Mass of the black hole is estimated using inner disc radius, bolometric luminosity, and two-component flow model to be 3–9 M⊙. Finally, we discuss the possible implications of our findings.

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A broad-band X-ray spectral study of the Seyfert 1 galaxy ESO 141–G055 with XMM–Newton and NuSTAR

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2259 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4213-4221

Author(s):

Ritesh Ghosh ◽

Sibasish Laha

Keyword(s):

Black Hole ◽

Spectral Study ◽

Column Density ◽

Broad Band ◽

Accretion Disc ◽

Physical Models ◽

X Ray ◽

Reflection Model ◽

Ionization Parameter

ABSTRACT We have extensively studied the broad--band X-ray spectra of the source ESO 141–G055 using all available XMM–Newton and NuSTAR observations. We detect a prominent soft excess below $2\rm \, \, {\rm keV}$, a narrow Fe line, and a Compton hump ($\gt 10\rm \, \, {\rm keV}$). The origin of the soft excess is still debated. We used two models to describe the soft excess: the blurred reflection from the ionized accretion disc and the intrinsic thermal Comptonization model. We find that both of these models explain the soft excess equally well. We confirm that we do not detect any broad Fe line in the X-ray spectra of this source, although both the physical models prefer a maximally spinning black hole scenario (a > 0.96). This may mean that either the broad Fe line is absent or blurred beyond detection. The Eddington rate of the source is estimated to be $\lambda _{\rm \, Edd}\sim 0.31$. In the reflection model, the Compton hump has a contribution from both ionized and neutral reflection components. The neutral reflector which simultaneously describes the narrow Fe K α and the Compton hump has a column density of $N_{\rm H} \ge 7\times 10^{24} \, \rm cm^{-2}$. In addition, we detect a partially covering ionized absorption with ionization parameter $\log \xi /\rm \, erg\, cm\, s^{-1}$ = $0.1^{+0.1}_{-0.1}$ and column density $N_{\rm H} =20.6^{+1.0}_{-1.0}\times 10^{22} \, \rm cm^{-2}$ with a covering factor of $0.21^{+0.01}_{-0.01}$.

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DISCOVERY OF PHOTON INDEX SATURATION IN THE BLACK HOLE BINARY GRS 1915+105

The Astrophysical Journal ◽

10.1088/0004-637x/706/2/1463 ◽

2009 ◽

Vol 706 (2) ◽

pp. 1463-1483 ◽

Cited By ~ 30

Author(s):

Lev Titarchuk ◽

Elena Seifina

Keyword(s):

Black Hole ◽

Photon Index ◽

Black Hole Binary ◽

Index Saturation

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Rapid spectral transition of the black hole binary V404 Cygni

Astronomy and Astrophysics ◽

10.1051/0004-6361/201937191 ◽

2020 ◽

Vol 634 ◽

pp. A94

Author(s):

J. J. E. Kajava ◽

C. Sánchez-Fernández ◽

J. Alfonso-Garzón ◽

S. E. Motta ◽

A. Veledina

Keyword(s):

Black Hole ◽

Optical Data ◽

X Ray ◽

Rapid Changes ◽

Photon Index ◽

Order Of Magnitude ◽

Best Fitting ◽

Black Hole Binary ◽

Flux Increase ◽

Magnitude Increase

During the June 2015 outburst of the black hole binary V404 Cyg, rapid changes in the X-ray brightness and spectra were common. The INTEGRAL monitoring campaign detected spectacular Eddington-limited X-ray flares, but also rapid variations at much lower flux levels. On 2015 June 21 at 20 h 50 min, the 3–10 keV JEM-X data as well as simultaneous optical data started to display a gradual brightening from one of these low-flux states. This was followed 15 min later by an order-of-magnitude increase of flux in the 20–40 keV IBIS/ISGRI light curve in just 15 s. The best-fitting model for both the pre- and post-transition spectra required a Compton-thick partially covering absorber. The absorber parameters remained constant, but the spectral slope varied significantly during the event, with the photon index decreasing from Γ ≈ 3.7 to Γ ≈ 2.3. We propose that the rapid 20–40 keV flux increase was either caused by a spectral state transition that was hidden from our direct view, or that there was a sudden reduction in the amount of Compton down-scattering of the primary X-ray emission in the disk outflow.

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Spectro-timing analysis of MAXI J1535–571 using AstroSat

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz1774 ◽

2019 ◽

Vol 488 (1) ◽

pp. 720-727 ◽

Cited By ~ 5

Author(s):

Yash Bhargava ◽

Tomaso Belloni ◽

Dipankar Bhattacharya ◽

Ranjeev Misra

Keyword(s):

Black Hole ◽

Power Law ◽

Intermediate State ◽

Timing Analysis ◽

Physical Models ◽

Periodic Oscillations ◽

Black Hole Candidate ◽

Centroid Frequency ◽

Spacecraft Orbits ◽

Tight Correlation

Abstract We report the results of the analysis of an AstroSat observation of the black hole candidate MAXI J1535–571 during its hard-intermediate state. We studied the evolution of the spectral and timing parameters of the source during the observation. The observation covered a period of ∼5 d and consisted of 66 continuous segments, corresponding to individual spacecraft orbits. Each segment was analysed independently. The source count rate increased roughly linearly by ∼30 per cent. We modelled the spectra as a combination of radiation from a thermal disc component and a power law. The timing analysis revealed the presence of strong quasi-periodic oscillations with centroid frequency νQPO fluctuating in the range of 1.7–3.0 Hz. We found a tight correlation between the QPO centroid frequency νQPO and the power-law spectral index Γ, while νQPO appeared not to be correlated with the linearly increasing flux itself. We discuss the implications of these results on physical models of accretion.

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Probing Supercritical Accretion in Ultraluminous X-ray Source M82 X-1 by means of X-ray Spectral Evolution Analysis

EPJ Web of Conferences ◽

10.1051/epjconf/202024007005 ◽

2020 ◽

Vol 240 ◽

pp. 07005

Author(s):

Izatul Hafizah ◽

Kiki Vierdayanti

Keyword(s):

Black Hole ◽

Binary System ◽

Accretion Rate ◽

Spectral Evolution ◽

X Ray ◽

Mass Accretion Rate ◽

Blackbody Model ◽

Chi Squared ◽

Dominant State ◽

Black Hole Binary

We analyze the spectral evolution of ultraluminous X-ray source (ULX) M82 X-1 by means of spectral fitting. We use selected Swift/XRT data in 2014 and 2015. The flux of M82 X-1 increased by a factor of 2-3 from 2014 to 2015. Most of the data in 2015 show greater dominance of hard component than those of 2014. Due to moderate signal-to-noise ratio, we only fit each spectrum with power-law and disk blackbody model separately. The data in 2014 are better fitted with powerlaw model based on the value of reduced-chi squared. On the other hand, both powerlaw and diskbb models showed comparable re- duced chi-squared value for the data in 2015. We found that the range of spectral index for 2014 data is 1.65 < Γ < 2.08 and for 2015 data is 1.02 < Γ < 1.95 from the powerlaw model, resembling the range for that of black hole binary system at low mass accretion rate. We obtained higher innermost disk temper- ature from the disk blackbody model, 1.20 keV < Tin < 3.63 keV, compared to that of black hole binary system in the thermal state. The calculated innermost radius of the disk, Rin, varies between 0.99 to 4.89 RS assuming 10 M0 black hole which indicates that the spectral state is not in thermal dominant state but rather we suspect that M82 X-1 exhibits greater mass accretion rate than that of the thermal dominant state.

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Swift unveils the orbital period of IGR J18214-1318

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2505 ◽

2020 ◽

Vol 498 (2) ◽

pp. 2750-2756

Author(s):

G Cusumano ◽

A D’Aì ◽

A Segreto ◽

V La Parola ◽

M Del Santo

Keyword(s):

Orbital Period ◽

Timing Analysis ◽

Broad Band ◽

Physical Models ◽

High Mass ◽

Periodic Signal ◽

Deep Minimum ◽

Companion Star ◽

Bulk Motion ◽

Using Data

ABSTRACT We analysed 13 yr of the Neil Gehrels Swift Observatory survey data collected on the high-mass X-ray binary IGR J18214-1318. Performing the timing analysis, we detected a periodic signal of 5.42 d. From the companion star characteristics, we derived an average orbital separation of $\sim 41 \rm R_{\odot }\simeq 2 R_{\star }$. The spectral type of the companion star (O9) and the tight orbital separation suggest that IGR J18214-1318 is a wind-accreting source with eccentricity lower than 0.17. The intensity profile folded at the orbital period shows a deep minimum compatible with an eclipse of the source by the companion star. In addition, we report on the broad-band 0.6–100 keV spectrum using data from XMM–Newton, NuSTAR, and Swift, applying self-consistent physical models. We find that the spectrum is well fitted either by a pure thermal Comptonization component, or, assuming that the source is a neutron star accreting above the critical regime, by a combined thermal and bulk motion Comptonization model. In both cases, the presence of a local neutral absorption (possibly related to the thick wind of the companion star) is required.

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X-ray properties of reverberation-mapped AGNs with super-Eddington accreting massive black holes

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002756 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 143-143

Author(s):

Jaya Maithil ◽

Michael S. Brotherton ◽

Bin Luo ◽

Ohad Shemmer ◽

Sarah C. Gallagher ◽

...

Keyword(s):

Black Holes ◽

Black Hole ◽

Accretion Rate ◽

Time Lags ◽

Black Hole Mass ◽

Host Galaxies ◽

Massive Black Holes ◽

X Ray ◽

Photon Index ◽

The Impact

AbstractActive Galactic Nuclei (AGN) exhibit multi-wavelength properties that are representative of the underlying physical processes taking place in the vicinity of the accreting supermassive black hole. The black hole mass and the accretion rate are fundamental for understanding the growth of black holes, their evolution, and the impact on the host galaxies. Recent results on reverberation-mapped AGNs show that the highest accretion rate objects have systematic shorter time-lags. These super-Eddington accreting massive black holes (SEAMBHs) show BLR size 3-8 times smaller than predicted by the Radius-Luminosity (R-L) relationship. Hence, the single-epoch virial black hole mass estimates of highly accreting AGNs have an overestimation of a factor of 3-8 times. SEAMBHs likely have a slim accretion disk rather than a thin disk that is diagnostic in X-ray. I will present the extreme X-ray properties of a sample of dozen of SEAMBHs. They indeed have a steep hard X-ray photon index, Γ, and demonstrate a steeper power-law slope, ασx.

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