scholarly journals Rapid spectral transition of the black hole binary V404 Cygni

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.

scholarly journals The awakening beast in the Seyfert 1 Galaxy KUG 1141+371 – I

2020 ◽  
Vol 501 (1) ◽  
pp. 916-932
Author(s):  
Jiachen Jiang ◽  
Huaqing Cheng ◽  
Luigi C Gallo ◽  
Luis C Ho ◽  
Douglas J K Buisson ◽  
...  
Keyword(s):  
Black Hole ◽  
Accretion Rate ◽  
Continuum Emission ◽  
Simultaneous Increase ◽  
Steady Increase ◽  
X Ray ◽  
The Awakening ◽  
Order Of Magnitude ◽  
Flux Increase ◽  
Eddington Limit

ABSTRACT KUG 1141+371 is a Seyfert 1 galaxy that shows a simultaneous flux increase in the optical and UV bands in the past decade. For instance, the latest Swift observation in 2019 shows that the UVW2 flux of the active galactic nucleus in KUG 1141+371 has increased by over one order of magnitude since 2009. Meanwhile, the soft X-ray flux of KUG 1141+371 also shows a steady increase by one order of magnitude since 2007. The significant multiwavelength luminosity change is likely due to a boost of mass accretion rate from approximately $0.6{{\ \rm per\ cent}}$ of the Eddington limit to $3.2{{\ \rm per\ cent}}$, assuming a black hole mass of 108 M⊙. In this work, we conduct detailed multi-epoch X-ray spectral analysis focusing on the variability of the X-ray continuum emission and the puzzling soft excess emission. In addition, our SED models also suggest a simultaneous increase of disc temperature and a decreasing inner disc radius along with the increasing accretion rate. Finally, we discuss possible connection between KUG 1141+371 and black hole transients in outburst.

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

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.

scholarly journals Review of the soft-X-ray laser research at CEL-V

1991 ◽  
Vol 9 (2) ◽  
pp. 493-499
Author(s):  
D. Naccache ◽  
J-L. Bourgade ◽  
P. Combis ◽  
C. J. Keane ◽  
J-P. Le Breton ◽  
...  
Keyword(s):  
Atomic Number ◽  
Collisional Excitation ◽  
X Ray ◽  
Order Of Magnitude ◽  
Laser Experiments ◽  
Magnitude Increase

We present some significant results of collisional excitation X-ray laser experiments in plasmas produced by a laser. We studied the amplification in Ne- and Ni-like ions by varying both the nature and the thickness of targets, the irradiation, and the wavelength of the driving laser. Some potentially interesting scalings as a function of the atomic number of the lasing element are demonstrated in the Ne-like system. An order-of-magnitude increase in gain in the Ni-like experiments was determined.

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.

X-ray observations of the black hole binary V404 Cygni in quiescence

1994 ◽  
Author(s):  
R. M. Wagner ◽  
S. G. Starrfield ◽  
T. J. Kreidl ◽  
S. B. Howell ◽  
R. M. Hjellming
Keyword(s):  
Black Hole ◽  
X Ray ◽  
Black Hole Binary

scholarly journals Optical Photometry of LMXBs: UW CrB (=MS 1603+260) and V1408 Aql (=4U 1957+115)

2015 ◽  
Vol 2 (1) ◽  
pp. 50-54
Author(s):  
P. A. Mason ◽  
E. L. Robinson ◽  
S. Gomez ◽  
J. V. Segura
Keyword(s):  
Black Hole ◽  
Orbital Period ◽  
Light Curves ◽  
Optical Data ◽  
Published Data ◽  
Type I ◽  
Optical Photometry ◽  
Mean Intensity ◽  
X Ray ◽  
Low Mass

We present new optical observations of V1408 Aql (= 4U 1957+115), the only low mass X-ray binary, black hole candidate known to be in a persistently soft state. We combine new broadband optical photometry with previously published data and derive a precise orbital ephemeris. The optical light curves display sinusoidal variations modulated on the orbital period as well as large night to night changes in mean intensity. The amplitude of the variations increases with mean intensity while maintaining sinusoidal shape. Considering the set of constraints placed by the X-ray and optical data we argue that V1408 Aql may harbor a very low mass black hole. Optical light curves of UW CrB display partial eclipses of the accretion disk by the donor star that vary both in depth and orbital phase. The new eclipses of UW CrB in conjunction with published eclipse timings are well fitted with a linear ephemeris. We derive an upper limit to the rate of change of the orbital period. By including the newly observed type I bursts with published bursts in our analysis, we find that optical bursts are not observed between orbital phases 0.93 and 0.07, i.e. they are not observable during partial eclipses of the disk.

scholarly journals A spectral study of the black hole X-ray binary MAXI J1820+070 with AstroSat and NuSTAR

2020 ◽  
Vol 498 (4) ◽  
pp. 5873-5884
Author(s):  
Sudip Chakraborty ◽  
Nilam Navale ◽  
Ajay Ratheesh ◽  
Sudip Bhattacharyya
Keyword(s):  
Black Hole ◽  
Broad Band ◽  
X Ray ◽  
Reflection Model ◽  
Temporal Features ◽  
Source State ◽  
Hard State ◽  
Independent Observations ◽  
Best Fitting ◽  
Fitting Model

ABSTRACT MAXI J1820+070 is a newly discovered transient black hole X-ray binary, which showed several spectral and temporal features. In this work, we analyse the broad-band X-ray spectra from all three simultaneously observing X-ray instruments onboard AstroSat, as well as contemporaneous X-ray spectra from NuSTAR, observed during the hard state of MAXI J1820+070 in 2018 March. Implementing a combination of multicolour disc model, relativistic blurred reflection model relxilllpcp, and a distant reflection in the form of xillvercp, we achieve reasonable and consistent fits for AstroSat and NuSTAR spectra. The best-fitting model suggests a low temperature disc (kTin ∼ 0.3 keV), iron overabundance (AFe ∼ 4–5 solar), a short lamp-post corona height (h ≲ 8Rg), and a high corona temperature (kTe ∼ 115–150 keV). Addition of a second Comptonization component leads to a significantly better fit, with the kTe of the second Comptonization component being ∼14–18 keV. Our results from independent observations with two different satellites in a similar source state indicate an inhomogeneous corona, with decreasing temperature attributed to increasing height. Besides, utilizing the broader energy coverage of AstroSat, we estimate the black hole mass to be 6.7–13.9 M⊙, consistent with independent measurements reported in the literature.

scholarly journals Spikey: self-lensing flares from eccentric SMBH binaries

2020 ◽  
Vol 495 (4) ◽  
pp. 4061-4070 ◽  
Author(s):  
Betty X Hu ◽  
Daniel J D’Orazio ◽  
Zoltán Haiman ◽  
Krista Lynne Smith ◽  
Bradford Snios ◽  
...  
Keyword(s):  
Rest Frame ◽  
Relativistic Effects ◽  
Light Curves ◽  
Optical Data ◽  
Spectral Slope ◽  
X Ray ◽  
Periodic Behaviour ◽  
Black Hole Binary ◽  
High Cadence ◽  
Rule Out

ABSTRACT We examine the light curves of two quasars, motivated by recent suggestions that a supermassive black hole binary (SMBHB) can exhibit sharp lensing spikes. We model the variability of each light curve as due to a combination of two relativistic effects: the orbital relativistic Doppler boost and gravitational binary self-lensing. In order to model each system, we extend previous Doppler plus self-lensing models to include eccentricity. The first quasar is identified in optical data as a binary candidate with a 20-yr period (Ark 120), and shows a prominent spike. For this source, we rule out the lensing hypothesis and disfavour the Doppler-boost hypothesis due to discrepancies in the measured versus recovered values of the binary mass and optical spectral slope. The second source, which we nickname Spikey, is the rare case of an active galactic nucleus identified in Kepler’s high-quality, high-cadence photometric data. For this source, we find a model, consisting of a combination of Doppler modulation and a narrow symmetric lensing spike, consistent with an eccentric SMBHB with a mass of $M_{\text{tot}} = 3\times 10^{7} {\, \mathrm{M}_{\odot }}$, rest-frame orbital period T = 418 d, eccentricity e = 0.5, and seen at an inclination of 8○ from edge-on. This interpretation can be tested by monitoring Spikey for periodic behaviour and recurring flares in the next few years. In preparation for such monitoring, we present the first X-ray observations of this object taken by the Neil Gehrels Swift Observatory.

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