摘要：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 hardness-intensity 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.
关键词：accretion, accretion disks;black hole physics;X-rays: stars;X-rays: individuals: Swift J1842.5-1124;X-rays: binaries
