We investigate systematically four outbursts of black hole system GX 339-4 observed by the Rossi X-ray Timing Explorer (RXTE) in both spectral and timing domains and find that these outbursts have some common properties, although they experience different ‘q’ tracks in the hardness–intensity diagram (HID). While the spectral indices are around 1.5 in the low/hard state (LHS) and 2.4 in the soft intermediate state (SIMS) and high/soft state (HSS), the spectral parameters of thermal, non-thermal, and reflection components vary significantly in transitions from the LHS to HIMS. Also, the quasi-periodic oscillation (QPO) shows a peculiar behaviour during the state transition between the LHS and HIMS: the RMS drop of the type C fundamental QPO is accompanied by the appearance of the second harmonic. Interestingly, the QPO RMS is found to have a similar linear relationship with the non-thermal fraction of emission in different outbursts. These findings provide more clues to aid our understanding of the outbursts of a black hole X-ray binary system.

We present a systematic analysis of type C quasiperiodic oscillation (QPO) observations of H1743-322 throughout the Rossi X-ray Timing Explorer era. We find that, while different outbursts have significant flux differences, they show consistent positive correlations between the QPO fractional rms amplitude and nonthermal fraction of the emission, which indicate an independence of the intrinsic QPO rms on individual outburst brightnesses in H1743-322. However, the dependence of the QPO rms on frequency is different between the outburst rise and decay phases, where the QPO fractional rms of the decay phase is significantly lower than that of the rise phase at low frequencies. The spectral analysis also reveals different ranges of coronal temperature between the two outburst stages. A semiquantitative analysis shows that the Lense–Thirring precession model could be responsible for the QPO rms differences, requiring a variable coronal geometric shape. However, the variable-Comptonization model could also account for the findings. The fact that the rms differences and the hysteresis traces in the hardness–intensity diagram accompany each other indicates a connection between the two phenomena. By correlating the findings with QPO phase lags and the quasi-simultaneous radio flux previously published, we propose there could be corona-jet transitions in H1743-322 similar to those that have been recently reported in GRS 1915+105.

Zero-dimensional (0D) halide perovskites have attracted extensive attention for their potential applications in solid-state lighting and X-ray detection due to their fascinating optoelectronic properties and convenient solution processability. Herein, we report the synthesis and photophysical properties of high-quality Sb 3+ -doped 0D Rb 2 ScCl 5 (H 2 O) perovskite single crystals. The pristine crystals exhibit weak yellow self-trapped exciton (STE) emission peaking at 632 nm. The emission quantum yield can be dramatically enhanced from less than 1% to about 53% via Sb 3+ doping. Spectroscopic characterizations indicate that the photoluminescence enhancement is a result of the efficient energy transfer from Sb 3+ to the emissive STEs. Additionally, 0.2%Sb 3+ :Rb 2 ScCl 5 (H 2 O) single crystals exhibit potential application in direct X-ray detection with a high sensitivity of 58.5 μC Gy −1 cm −2 .

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