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

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 $0.21^{+0.01}_{-0.01}$.

scholarly journals Broad-band spectral study of X-ray transient MAXI J1820+070 using Swift/XRT and NuSTAR

2019 ◽  
Vol 487 (4) ◽  
pp. 5946-5951 ◽  
Author(s):  
Priya Bharali ◽  
Jaiverdhan Chauhan ◽  
Kalyanee Boruah
Keyword(s):  
Thermal Emission ◽  
Broad Band ◽  
Compact Object ◽  
Black Body ◽  
Gravitational Radius ◽  
X Ray ◽  
Stable Circular Orbit ◽  
Hard State ◽  
Best Fitting ◽  
Band Spectra

ABSTRACT We report on a NuSTAR and Swift/XRT observation of the newly discovered X-ray transient MAXI J1820+070. Swift/XRT and NuSTAR have concurrently observed the newly detected source on 2018 March 14. We have simultaneously fitted the broad-band spectra obtained from Swift/XRT and NuSTAR. The observed joint spectra in the energy range 0.6–78.0 keV are well modeled with a weak disc black-body emission, dominant thermal Comptonization, and relativistic reflection fraction. We have detected a fluorescent Iron-Kα line relativistically broadened and a Compton hump at ∼30 keV. We constrain the inner disc radius as well as the disc inclination angle, and their values are found to be 4.1$^{+0.8}_{-0.6}$RISCO (where RISCO ≡ radius of the innermost stable circular orbit) or 5.1$^{+1.0}_{-0.7}$ rg (where rg ≡ gravitational radius) and 29.8$^{+3.0}_{-2.7}$°, respectively. The best-fitting broad-band spectra suggest that the source was in the hard state and evolving. The source emission is best described by weak thermal emission along with strong thermal Comptonization from a relatively cold, optically thick, geometrically thin and ionized accretion disc. X-ray spectral modeling helps us to understand the accretion and ejection properties in the vicinity of the compact object.

X-ray spectral and timing studies of black hole transients in the hard state at low luminosity

2012 ◽  
Author(s):  
John A. Tomsick ◽  
Kazutaka Yamaoka ◽  
Emrah Kalemci ◽  
Stéphane Corbel ◽  
Philip Kaaret ◽  
...  
Keyword(s):  
Black Hole ◽  
X Ray ◽  
Hard State

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 Thermal and radiation driving can produce observable disc winds in hard-state X-ray binaries

2020 ◽  
Vol 492 (4) ◽  
pp. 5271-5279 ◽  
Author(s):  
Nick Higginbottom ◽  
Christian Knigge ◽  
Stuart A Sim ◽  
Knox S Long ◽  
James H Matthews ◽  
...  
Keyword(s):  
Black Hole ◽  
Binary Systems ◽  
Velocity Structure ◽  
Spectral Energy ◽  
X Ray ◽  
Black Hole Binaries ◽  
Soft State ◽  
Before And After ◽  
Hard State ◽  
New Generation

ABSTRACT X-ray signatures of outflowing gas have been detected in several accreting black hole binaries, always in the soft state. A key question raised by these observations is whether these winds might also exist in the hard state. Here, we carry out the first full-frequency radiation hydrodynamic simulations of luminous (${L = 0.5 \, L_{\mathrm{\mathrm{ Edd}}}}$) black hole X-ray binary systems in both the hard and the soft state, with realistic spectral energy distributions (SEDs). Our simulations are designed to describe X-ray transients near the peak of their outburst, just before and after the hard-to-soft state transition. At these luminosities, it is essential to include radiation driving, and we include not only electron scattering, but also photoelectric and line interactions. We find powerful outflows with ${\dot{M}_{\mathrm{ wind}} \simeq 2 \, \dot{M}_{\mathrm{ acc}}}$ are driven by thermal and radiation pressure in both hard and soft states. The hard-state wind is significantly faster and carries approximately 20 times as much kinetic energy as the soft-state wind. However, in the hard state the wind is more ionized, and so weaker X-ray absorption lines are seen over a narrower range of viewing angles. Nevertheless, for inclinations ≳80°, blueshifted wind-formed Fe xxv and Fe xxvi features should be observable even in the hard state. Given that the data required to detect these lines currently exist for only a single system in a luminous hard state – the peculiar GRS 1915+105 – we urge the acquisition of new observations to test this prediction. The new generation of X-ray spectrometers should be able to resolve the velocity structure.

scholarly journals A stochastic propagation model to the energy dependent rapid temporal behaviour of Cygnus X-1 as observed by AstroSat in the hard state

2019 ◽  
Vol 486 (2) ◽  
pp. 2964-2975 ◽  
Author(s):  
Bari Maqbool ◽  
Sneha Prakash Mudambi ◽  
R Misra ◽  
J S Yadav ◽  
S B Gudennavar ◽  
...  
Keyword(s):  
Time Lag ◽  
Broad Band ◽  
Propagation Model ◽  
Large Area ◽  
Temporal Behaviour ◽  
X Ray ◽  
Single Temperature ◽  
Hard State ◽  
Band Spectra ◽  
Energy Dependent

Abstract We report the results from analysis of six observations of Cygnus X-1 by Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) onboard AstroSat, when the source was in the hard spectral state as revealed by the broad-band spectra. The spectra obtained from all the observations can be described by a single-temperature Comptonizing region with disc and reflection components. The event mode data from LAXPC provides unprecedented energy dependent fractional root mean square (rms) and time-lag at different frequencies which we fit with empirical functions. We invoke a fluctuation propagation model for a simple geometry of a truncated disc with a hot inner region. Unlike other propagation models, the hard X-ray emission (>4 keV) is assumed to be from the hot inner disc by a single-temperature thermal Comptonization process. The fluctuations first cause a variation in the temperature of the truncated disc and then the temperature of the inner disc after a frequency dependent time delay. We find that the model can explain the energy dependent rms and time-lag at different frequencies.

scholarly journals Broad-band spectral energy distribution of the X-ray transient Swift J1745−26 from outburst to quiescence

2020 ◽  
Vol 637 ◽  
pp. A2
Author(s):  
Sylvain Chaty ◽  
Francis Fortin ◽  
Alicia López-Oramas
Keyword(s):  
Energy Distribution ◽  
Light Curve ◽  
Spectral Energy Distribution ◽  
Broad Band ◽  
Spectral Energy ◽  
X Ray ◽  
Upper Limit ◽  
Spectral Break ◽  
Hard State ◽  
Low Mass

Aims. We aim to analyse our study of the X-ray transient Swift J1745−26, using observations obtained from its outburst in September 2012, up to its decay towards quiescence in March 2013. Methods. We obtained optical and infrared observations, through override programme at ESO/VLT with FORS2 and ISAAC instruments, and added archival optical (VLT/VIRCAM), radio and X-ray (Swift) observations, to build the light curve and the broad-band spectral energy distribution (SED) of Swift J1745−26. Results. We show that, during its outburst and also during its decay towards quiescence, Swift J1745−26 SED can be adjusted, from infrared up to X-rays, by the sum of both a viscous irradiated multi-colour black body emitted by an accretion disc, and a synchrotron power law at high energy. In the radio domain, the SED arises from synchrotron emission from the jet. While our SED fitting confirms that the source remained in the low/hard state during its outburst, we determine an X-ray spectral break at frequency 3.1 ≤ νbreak ≤ 3.4 × 1014 Hz, and a radio spectral break at 1012 Hz ≤ νbreak ≤ 1013 Hz. We also show that the system is compatible with an absorption AV of ∼7.69 mag, lies within a distance interval of D ∼ [2.6 − 4.8] kpc with an upper limit of orbital period Porb = 11.3 h, and that the companion star is a late spectral type in the range K0–M0 V, confirming that the system is a low-mass X-ray binary. We finally plot the position of Swift J1745−26 on an optical-infrared – X-ray luminosity diagram: its localisation on this diagram is consistent with the source staying in the low-hard state during outburst and decay phases. Conclusions. By using new observations obtained at ESO/VLT with FORS2 and ISAAC, and adding archival optical (VLT/VIRCAM), radio and X-ray (Swift) observations, we built the light curve and the broad-band SED of Swift J1745−26, and we plotted its position on an optical-infrared – X-ray luminosity diagram. By fitting the SED, we characterized the emission of the source from infrared, via optical, up to X-ray domain, we determined the position of both the radio and X-ray spectral breaks, we confirmed that it remained in the low-hard state during outburst and decay phases, and we derived its absorption, distance interval, orbital period upper limit, and the late-type nature of companion star, confirming Swift J1745−26 is a low-mass X-ray binary.

X-Ray Observations of M32 with ASCA

1998 ◽  
Vol 188 ◽  
pp. 291-292
Author(s):  
T. Toneri ◽  
K. Hayashida ◽  
M. Loewenstein
Keyword(s):  
Black Hole ◽  
Mass Concentration ◽  
Elliptical Galaxy ◽  
Broad Band ◽  
The Other ◽  
Central Black Hole ◽  
Massive Black Hole ◽  
X Ray ◽  
Eddington Limit

M32 is the nearest dwarf elliptical galaxy. Its center is known to have a mass concentration of 3 × 106 M⊙, which is usually interpreted as an evidence of a super massive black hole. We observed M32 with ASCA two times in July and August of 1996. An X-ray source was detected at the center of M32 and its first broad-band X-ray spectra were obtained. ASCA observations of M32 limit the activity of the central black hole to be less than 10−6 times of the Eddington limit. We also found two other bright sources within 12 arcmin from the M32 center. One is the newly appeared X-ray source and the other is G144. In this paper, we summarize the results on the new source and G144. For M32, please refer to the publication (Loewenstein et al. 1997).

A broad-band X-ray telescope observation of the black hole candidate LMC X-1

1994 ◽  
Vol 422 ◽  
pp. 243 ◽  
Author(s):  
Eric M. Schlegel ◽  
F. E. Marshall ◽  
R. F. Mushotzky ◽  
A. P. Smale ◽  
K. A. Weaver ◽  
...  
Keyword(s):  
Black Hole ◽  
Broad Band ◽  
X Ray ◽  
Black Hole Candidate ◽  
Telescope Observation

scholarly journals The unusual broad-band X-ray spectral variability of NGC 1313 X-1 seen with XMM–Newton, Chandra, and NuSTAR

2020 ◽  
Vol 494 (4) ◽  
pp. 6012-6029 ◽  
Author(s):  
D J Walton ◽  
C Pinto ◽  
M Nowak ◽  
M Bachetti ◽  
R Sathyaprakash ◽  
...  
Keyword(s):  
Black Hole ◽  
Broad Band ◽  
High Energy ◽  
Accretion Disc ◽  
Continuum Emission ◽  
Spectral Variability ◽  
Temperature Behaviour ◽  
Temperature Relation ◽  
X Ray ◽  
Constant Area

ABSTRACT We present results from the major coordinated X-ray observing programme on the ULX NGC 1313 X-1 performed in 2017, combining XMM–Newton, Chandra, and NuSTAR, focusing on the evolution of the broad-band (∼0.3–30.0 keV) continuum emission. Clear and unusual spectral variability is observed, but this is markedly suppressed above ∼10–15 keV, qualitatively similar to the ULX Holmberg IX X-1. We model the multi-epoch data with two-component accretion disc models designed to approximate super-Eddington accretion, allowing for both a black hole and a neutron star accretor. With regards to the hotter disc component, the data trace out two distinct tracks in the luminosity–temperature plane, with larger emitting radii and lower temperatures seen at higher observed fluxes. Despite this apparent anticorrelation, each of these tracks individually shows a positive luminosity–temperature relation. Both are broadly consistent with L ∝ T4, as expected for blackbody emission with a constant area, and also with L ∝ T2, as may be expected for an advection-dominated disc around a black hole. We consider a variety of possibilities for this unusual behaviour. Scenarios in which the innermost flow is suddenly blocked from view by outer regions of the super-Eddington disc/wind can explain the luminosity–temperature behaviour, but are difficult to reconcile with the lack of strong variability at higher energies, assuming this emission arises from the most compact regions. Instead, we may be seeing evidence for further radial stratification of the accretion flow than is included in the simple models considered, with a combination of winds and advection resulting in the suppressed high-energy variability.

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