The Evolution of GX 339-4 in the Low-hard State as Seen by NuSTAR and Swift

Grinberg

et al. 2018

ApJ

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We present a detailed spectral analysis of the black hole binary XTEJ1752−223in the hard state of its 2009 outburst. Regular monitoring of this source by the Rossi X-ray Timing Explorer mission provided high signal-tonoise spectra along the outburst rise and decay. During one full month this source stalled at ∼30% of its peak count rate at a constant hardness and intensity. By combining all the data in this exceptionally stable hard state, we obtained an aggregate proportional counter array spectrum (3-45 keV) with 100million counts, and a corresponding high energy X-ray timing experiment spectrum (20-140 keV) with 5.8million counts. Implementing a version of our reflection code with a physical model for Comptonization, we obtain tight constraints on important physical parameters for this system. In particular, the inner accretion disk is measured very close in, at R in =1.7±0.4 R g . Assuming R in =R ISCO , we find a relatively high black hole spin (a * =0.92±0.06). Imposing a lamppost geometry, we obtain a low inclination (i=35°±4°), which agrees with the upper limit found in the radio (i<49°). However, we note that this model cannot be statistically distinguished from a non-lamppost model with a free emissivity index, for which the inclination is markedly higher. Additionally, we find a relatively cool corona (57-70 keV) and large iron abundance (3.3-3.7 solar). We further find that properly accounting for Comptonization of the reflection emission improves the fit significantly and causes an otherwise low reflection fraction (∼0.2-0.3) to increase by an order of magnitude, in line with geometrical expectations for a lamppost corona. We compare these results with similar investigations reported for GX339−4in its bright hard state.

Section: Discussionsupporting

confidence: 57%

Reflection Spectroscopy of the Black Hole Binary XTE J1752−223 in Its Long-stable Hard State

Grinberg

et al. 2018

ApJ

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“…During the hard state, Meyer et al (2000) had predicted that thermal conduction of heat from the corona will cause the inner disk to evaporate, leading to an optically thick and geometrically thin disk, that is truncated at some significant distance away from the black hole. While there is evidence for truncation during the hard state (Mahmoud et al 2019), and at luminosities below 0.1% of the Eddington limit (L Edd ) for GX 339-4 (Tomsick et al 2009), measurements of the reflection component in the bright hard state (> 5% L Edd ) have lead to estimates of inner radii very close to the ISCO for several sources, including GX 339-4 (García et al 2015;Steiner et al 2017;Wang-Ji et al 2018;García et al 2019). While there exists abundant evidence for truncated disk at low/hard state, and the disk extending until ISCO by the time the source reaches bright soft state (Gierliński & Done 2004;Steiner et al 2010;Penna et al 2010;Zhu et al 2012), the evolution of the disk and the coronal parameters, especially the inner disk's radius during the bright intermediate states is not well understood.…”

Section: Introductionmentioning

confidence: 99%

Evolution of the Accretion Disk–Corona during the Bright Hard-to-soft State Transition: A Reflection Spectroscopic Study with GX 339–4

Sridhar

et al. 2020

ApJ

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We present the analysis of several observations of the black hole binary GX 339-4 during its bright intermediate states from two different outbursts (2002 and 2004), as observed by RXTE/PCA. We perform a consistent study of its reflection spectrum by employing the relxill family of relativistic reflection models to probe the evolutionary properties of the accretion disk including the inner disk radius (R in ), ionization parameter (ξ), temperatures of the inner disk (T in ), corona (kT e ), and its optical depth (τ ). Our analysis indicates that the disk inner edge approaches the inner-most stable circular orbit (ISCO) during the early onset of bright hard state, and that the truncation radius of the disk remains low (< 9R g ) throughout the transition from hard to soft state. This suggests that the changes observed in the accretion disk properties during the state transition are driven by variation in accretion rate, and not necessarily due to changes in the inner disk's radius. We compare the aforementioned disk properties in two different outbursts with state transitions occurring at dissimilar luminosities, and find identical evolutionary trends in the disk properties, with differences only seen in corona's kT e and τ . We also perform an analysis by employing a self-consistent Comptonized accretion disk model accounting for the scatter of disk photons by the corona, and measure low inner disk truncation radius across the bright intermediate states, using the temperature dependent values of spectral hardening factor, thereby independently confirming our results from the reflection spectrum analysis.

“…Figure 3 shows the data-to-model ratios and the contributions to the total χ 2 of the best-fitting. No distant reflection from the outer disc, the wind or the surface of companion (Wang-Ji et al 2018;Xu et al 2018), was necessary, which is attributed to that the RXTE is not sensitive to the narrow line. When the distant reflection component is added using xillver, the statistic is not improved with χ 2 ν = 0.87 (385.82/445).…”

Section: Analysis and Resultsmentioning

confidence: 99%

The spin measurement of the black hole in 4U 1543-47 constrained with the X-ray reflected emission

Dong

Monthly Notices of the Royal Astronomical Society

et al. 2020

4U 1543-47 is a low mass X-ray binary which harbours a stellar-mass black hole located in our Milky Way galaxy. In this paper, we revisit 7 data sets which were in the Steep Power Law state of the 2002 outburst. The spectra were observed by the Rossi X-ray Timing Explorer. We have carefully modelled the X-ray reflection spectra, and made a joint-fit to these spectra with relxill, for the reflected emission. We found a moderate black hole spin, which is 0.67 +0.15 −0.08 at 90% statistical confidence. Negative and low spins (< 0.5) at more than 99% statistical confidence are ruled out. In addition, our results indicate that the model requires a super-solar iron abundance: 5.05 +1.21 −0.26 , and the inclination angle of the inner disc is 36.3 +5.3 −3.4 degrees. This inclination angle is appreciably larger than the binary orbital inclination angle (∼21 degrees); this difference is possibly a systematic artefact of the artificially low-density employed in the reflection model for this X-ray binary system.