No Arabic abstract
MAXI J1659-152 was discovered on 2010 September 25 as a new X-ray transient, initially identified as a gamma-ray burst, but was later shown to be a new X-ray binary with a black hole as the most likely compact object. Dips in the X-ray light curves have revealed that MAXI J1659-152 is the shortest period black hole candidate identified to date. Here we present the results of a large observing campaign at radio, sub-millimeter, near-infrared (nIR), optical and ultraviolet (UV) wavelengths. We have combined this very rich data set with the available X-ray observations to compile a broadband picture of the evolution of this outburst. We have performed broadband spectral modeling, demonstrating the presence of a spectral break at radio frequencies and a relationship between the radio spectrum and X-ray states. Also, we have determined physical parameters of the accretion disk and put them into context with respect to the other parameters of the binary system. Finally, we have investigated the radio-X-ray and nIR/optical/UV-X-ray correlations up to ~3 years after the outburst onset to examine the link between the jet and the accretion disk, and found that there is no significant jet contribution to the nIR emission when the source is in the soft or intermediate X-ray spectral state, consistent with our detection of the jet break at radio frequencies during these states.
We present 5 years of optical and infrared data of the black hole candidate MAXI J1659-152 covering its 2010 outburst, decay and quiescence. Combining optical data taken during the outburst decay, we obtain an orbital period of 2.414 $pm$ 0.005 h, in perfect agreement with the value previously measured from X-ray dips. In addition, we detect a clear H$alpha$ excess in MAXI J1659-152 with data taken during the outburst decay. We also detect a single hump modulation most likely produced by irradiation. Assuming that the maximum occurs at orbital phase 0.5, we constrain the phase of the X-ray dips to be ~ 0.65. We also detect the quiescent optical counterpart at r = 24.20 $pm$ 0.08, I = 23.32 $pm$ 0.02 and H = 20.7 $pm$ 0.1. These magnitudes provide colour indices implying an M2-M5 donor star assuming 60% contribution from a disc component in the r-band.
Following the detection of a bright new X-ray source, MAXI J1659-152, a series of observations was triggered with almost all currently flying high-energy missions. We report here on XMM-Newton, INTEGRAL and RXTE observations during the early phase of the X-ray outburst of this transient black-hole candidate. We confirm the dipping nature in the X-ray light curves. We find that the dips recur on a period of 2.4139+/-0.0005 hrs, and interpret this as the orbital period of the system. It is thus the shortest period black-hole X-ray binary known to date. Using the various observables, we derive the properties of the source. The inclination of the accretion disk with respect to the line of sight is estimated to be 60-75 degrees. The companion star to the black hole is possibly a M5 dwarf star, with a mass and radius of about 0.15 M_sun and 0.23 R_sun, respectively. The system is rather compact (orbital separation is about 1.35 R_sun) and is located at a distance of roughly 7 kpc. In quiescence, MAXI J1659-152 is expected to be optically faint, about 28 mag in the V-band.
We report on X-ray spectral and timing results of the new black hole candidate (BHC) MAXI J1659-152 with the orbital period of 2.41 hours (shortest among BHCs) in the 2010 outburst from 65 Rossi X-ray Timing Explorer (RXTE) observations and 8 simultaneous Swift and RXTE observations. According to the definitions of the spectral states in Remillard & McClintock (2006), most of the observations have been classified into the intermediate state. All the X-ray broadband spectra can be modeled by a multi-color disk plus a power-law with an exponential cutoff or a multi-color disk plus a Comptonization component. During the initial phase of the outburst, a high energy cutoff was visible at 30-40 keV. The innermost radius of the disk gradually decreased by a factor of more than 3 from the onset of the outburst and reached a constant value of 35 d_10 cos i^-1/2 km, where d_10 is the distance in units of 10 kpc and $i$ is the inclination. The type-C quasi-periodic oscillation (QPO) frequency varied from 1.6 Hz to 7.3 Hz in association with a change of the innermost radius, while the innermost radius remained constant during the type-B QPO detections at 1.6-4.1 Hz. Hence, we suggest that the origin of the type-B QPOs is different from that of type-C QPOs, the latter of which would originate from the disk truncation radius. Assuming the constant innermost radius in the latter phase of the outburst as the innermost stable circular orbit, the black hole mass in MAXI J1659-152 is estimated to be 3.6-8.0 M_solar for a distance of 5.3-8.6 kpc and an inclination angle of 60-75 degrees.
We present a broadband radio study of the transient jets ejected from the black hole candidate X-ray binary MAXI J1535-571, which underwent a prolonged outburst beginning on 2 September 2017. We monitored MAXI J1535-571 with the Murchison Widefield Array (MWA) at frequencies from 119 to 186 MHz over six epochs from 20 September to 14 October 2017. The source was quasi-simultaneously observed over the frequency range 0.84-19 GHz by UTMOST (the upgraded Molonglo Observatory Synthesis Telescope), the Australian Square Kilometre Array Pathfinder, the Australia Telescope Compact Array (ATCA), and the Australian Long Baseline Array (LBA). Using the LBA observations from 23 September 2017, we measured the source size to be $34pm1$ mas. During the brightest radio flare on 21 September 2017, the source was detected down to 119 MHz by the MWA, and the radio spectrum indicates a turnover between 250 and 500 MHz, which is most likely due to synchrotron self-absorption (SSA). By fitting the radio spectrum with a SSA model and using the LBA size measurement, we determined various physical parameters of the jet knot (identified in ATCA data), including the jet opening angle (= $4.5pm1.2^{circ}$) and the magnetic field strength (= $104^{+80}_{-78}$ mG). Our fitted magnetic field strength agrees reasonably well with that inferred from the standard equipartition approach, suggesting the jet knot to be close to equipartition. Our study highlights the capabilities of the Australian suite of radio telescopes to jointly probe radio jets in black hole X-ray binaries (BH-XRBs) via simultaneous observations over a broad frequency range, and with differing angular resolutions. This suite allows us to determine the physical properties of XRB jets. Finally, our study emphasizes the potential contributions that can be made by the low-frequency part of the Square Kilometre Array (SKA-Low) in the study of BH-XRBs.
MAXI J1535-571 is a Galactic black hole candidate X-ray binary that was discovered going into outburst in 2017 September. In this paper, we present comprehensive radio monitoring of this system using the Australia Telescope Compact Array (ATCA), as well as the MeerKAT radio observatory, showing the evolution of the radio jet during its outburst. Our radio observations show the early rise and subsequent quenching of the compact jet as the outburst brightened and then evolved towards the soft state. We constrain the compact jet quenching factor to be more than 3.5 orders of magnitude. We also detected and tracked (for 303 days) a discrete, relativistically-moving jet knot that was launched from the system. From the motion of the apparently superluminal knot, we constrain the jet inclination (at the time of ejection) and speed to $leq 45^{circ}$ and $geq0.69$c, respectively. Extrapolating its motion back in time, our results suggest that the jet knot was ejected close in time to the transition from the hard intermediate state to soft intermediate state. The launching event also occurred contemporaneously with a short increase in X-ray count rate, a rapid drop in the strength of the X-ray variability, and a change in the type-C quasi-periodic oscillation (QPO) frequency that occurs $>$2.5 days before the first appearance of a possible type-B QPO.