Related papers: The cross-correlation analysis in Z source GX 349+…
X-rays illuminating the accretion disc in active galactic nuclei give rise to an iron K line and its associated reflection spectrum which are lagged behind the continuum variability by the light-travel time from the source to the disc. The…
Luminous accreting stellar mass and supermassive black holes produce power-law continuum X-ray emission from a compact central corona. Reverberation time lags occur due to light travel time-delays between changes in the direct coronal…
Observations of the black hole X-ray binaries GX 339-4 and V404 Cygni have brought evidence of a strong correlation between radio and X-ray emission during the hard spectral state; however, now more and more sources, the so-called…
We analysed all X-ray data on the low-mass X-ray binary Cygnus X-2 obtained with Ginga. The analysis of the spectral and fast timing behaviour of these 4 years of data provides new insights in the behaviour of this Z source. We confirm the…
We analyze observations of the low mass X-ray binary 2S0921-63 obtained with the gratings and CCDs on Chandra and XMM. This object is a high inclination system showing evidence for an accretion disk corona (ADC). Such a corona has the…
We present long term monitoring of MCG-6-30-15 in X-rays, optical and near-IR wavelengths, collected over five years of monitoring. We determine the power spectrum density of all the observed bands and show that after taking into account…
Accreting black holes and neutron stars in their hard (low) state show not only very similar X/gamma-ray spectra but also that the behaviour of their light curves is quite similar which can be quantified as having similar power-density…
We investigate the X-ray enhancement and the long-term evolution of the recently discovered, second "low-B magnetar" Swift J1822.3-1606 in the frame of the fallback disk model. During a soft gamma burst episode, the inner disk matter is…
We analyze eleven NuSTAR and Swift observations of the black hole X-ray binary GX 339-4 in the hard state, six of which were taken during the end of the 2015 outburst, five during a failed outburst in 2013. These observations cover…
We report the first spectro-polarimetric investigation of the bright Z-type source GX 349+2 using simultaneous observations of \textit{IXPE}, \textit{NuSTAR} and \textit{Swift/XRT}. The source exhibited significant polarization in the 2-8…
X-ray reverberation lags from the vicinity of supermassive black holes have been detected in almost 30 AGN. The soft lag, which is the time delay between the hard and soft X-ray light curves, is usually interpreted as the time difference…
We have studied the spectro-temporal properties of the neutron star low mass X-ray binary GX 9$+$1 using data from \textit{NuSTAR/FPM} and \textit{AstroSat/SXT} and \textit{LAXPC}. The hardness-intensity diagram of the source showed it to…
We report results of a new spectral analysis of two BeppoSAX observations of the Z source GX 17+2. In one of the two observations the source exhibits a powerlaw-like hard (> 30 keV) X-ray tail which was described in a previous work by a…
We present an explanation of the Z-track phenomenon based on spectral fitting of RXTE observations of GX340+0 using the emission model previously shown to describe the dipping LMXB. In our Z-track model, the soft apex is a quiescent state…
We present our long term Chandra X-ray monitoring data for the gravitationally lensed quasar Q2237+0305 with 20 epochs spanning 10 years. We easily detect microlensing variability between the images in the full (0.2--8 keV), soft (0.2--2…
Context: Extensive, multi-wavelength monitoring campaigns of nearby and higher redshift active galactic nuclei (AGN) have shown that the UV/optical variations are well correlated with time delays which increase with increasing wavelength.…
Variations in the X-ray emission from the narrow line Seyfert 1 galaxy, Markarian 335 (Mrk 335), are studied on both long and short timescales through observations made between 2006 and 2013 with XMM-Newton, Suzaku and NuSTAR. Changes in…
The broad emission features in the Fe-Kalpha region of X-ray binary spectra represent an invaluable probe to constrain the geometry and the physics of these systems. Several Low Mass X-ray binary systems (LMXBs) containing a neutron star…
We perform a comprehensive wide-band ($3-100$keV) spectro-temporal analysis of 13 outbursting BH-XRBs, using data (quasi)simultaneous with radio observations to unravel the complex disc-jet connection. RXTE observations are analyzed for…
We report the first detection of X-ray polarization in the horizontal branch for GX 340+0 as obtained by Imaging X-ray Polarimetry Explorer (IXPE). A polarization degree of 4.3%$\pm$0.3% is obtained. This value is in agreement with the…