The X-ray view of black-hole candidateSwiftJ1842.5-1124 during its 2008 outburst

Abstract

Context. The spectral and temporal evolution during X-ray outbursts give important clues on the accretion process and radiation mechanism in black-hole X-ray binaries (BH XRBs). Aims. A set of Swift and RXTE observations were executed to monitor the 2008 outburst of the black-hole candidate Swift J1842.5-1124. We investigate these data to explore the accretion physics in BH XRBs. Methods. We carry out a comprehensive spectral and timing analysis on all the available pointing observations, including fitting both X-ray spectra and power density spectra, measuring the optical and near-ultraviolet flux density. We also search for correlations among the spectral and timing parameters. Results. The observed properties of Swift J1842.5-1124 are similar to other BH XRBs in many respects, for example the hardnessintensity diagram and hardness-rms diagram. The type-C quasi-periodic oscillations (QPOs) were observed as the source started to transit from the low-hard state to the high-soft state. The frequency of QPOs correlate with intensity and the hard component index, and anti-correlate with the hardness and the total fractional rms. These relations are consistent with the Lense-Thirring precession model. The estimated U-band flux changed with the X-ray flux, while the flux density at the V band remained 0.26 mJy. These results imply that the X-ray reprocessing or the tail of thermal emission from the outer disk contributes a significant fraction of the U-band radiation; alternatively, the companion star or the jet dominates the flux at longer wavelengths.

MeerKAT radio detection of the Galactic black hole candidate Swift J1842.5-1124 during its 2020 outburst

“…Markwardt et al (2008) suggested that the source is a BH binary that was evolving in the hard state, according to the X-ray spectral properties (e.g., combined black body and power law model with black body kT of 0.9 keV and photon index of 1.5) and the detection of a strong QPO at ≈ 0.8 Hz, together with the strong X-ray variability. In addition, the observed timing properties which were systematically studied by Zhao et al (2016), are similar to other BH XRBs in many respects, supporting a BH nature of this source. Furthermore, the peak of the hard X-ray light curve precedes the peak of the softer X-ray light curves by ∼ 10 days (Krimm et al 2013), which is larger than what has been seen in neutron star LMXB transients (Yu et al 2003(Yu et al , 2004, supporting the scenario in which the source is a candidate BH XRB (e.g., Krimm et al 2011;Brocksopp et al 2005).…”

A Statistical Analysis of the “Heartbeat” Behavior of GRS 1915+105

“…Note that low-frequency QPO signals detected in low-mass Xray binaries are generally connected with the hard component but not (or sometimes indirectly linked with) the thermal accretion disk (e.g. Belloni & Stella 2014;Motta et al 2015;Zhao et al 2016;Zhang et al 2017;Yan et al 2018).…”

A Machine Learning Approach For Classifying Low-mass X-ray Binaries Based On Their Compact Object Nature

“…LMXB and our trained model also predicts the same for 54% of its 97 observations. SWIFT J1842.5-1124 was classified by Zhao et al (2016) as a BH LMXB candidate and our trained model predicts it is a black hole for 51% of its observations. Apart from that it is also important to note that all the 13 sources in our prediction sample have an average SNR <100 which is the region where the algorithm has the worst performance as shown in Fig.…”