相关论文: Statistical properties of Fourier-based time-lag e…
Electromagnetic radiation from blazar jets often displays strong variability, extending from radio to $\gamma$-ray frequencies. In a few cases, this variability has been characterized using Fourier time lags, such as those detected in the…
Spectral timing analyses based upon wavelet transforms provide a new means to study the variability of the X-ray emission from accreting systems, including AGN, stellar mass black holes and neutron stars, and can be used to trace the time…
Variable continuum emission from AGN can be used to probe the structure of their accretion disks via reverberation mapping. Assuming a variable, hot inner light source irradiates the surrounding accretion disk, time delays between different…
Many AGN exhibit a highly variable luminosity. Some AGN also show a pronounced time delay between variations seen in their optical continuum and in their emission lines. In effect, the emission lines are light echoes of the continuum. This…
X-ray reverberation mapping is a powerful technique for probing the innermost accretion disk, whereas continuum reverberation mapping in the UV, optical, and infrared (UVOIR) reveals reprocessing by the rest of the accretion disk and…
Optical observations cannot resolve the structure of active galactic nuclei (AGN), and a unified model for AGN was inferred mostly from indirect methods. Optical reverberation mapping allowed us to constrain the spatial dimension of the…
The X-ray signal from active galactic nuclei and black hole X-ray binaries is highly variable on a range of timescales. This variability can be exploited to map the region of interest close to the black hole, which is far too small to…
X-ray observations of active galactic nuclei (AGN) show variability on timescales ranging from a few hours up to a few days. Some of this variability may be associated with occultation events by clouds in the broad line region. In this…
We develop models for time lag between maxima of the source brightness in different wavelengths during a transient flash of luminosity connected with a short period of increase of the mass flux onto the central compact object. We derive a…
In this paper, we present an updated version of our model (KYNXiltr) which considers thermal reverberation of a standard Novikov-Thorne accretion disc illuminated by an X-ray point-like source. Previously, the model considered only two…
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…
The origin of the soft X-ray excess below 2 keV in active galactic nuclei (AGNs) remains debated, with relativistic reflection from the inner accretion disk and warm Comptonization in an optically thick corona being the leading…
We use a 100 ks long XMM-Newton observation of the Narrow-Line Seyfert 1 galaxy Ark 564 and combine it with the month-long monitoring of the same source produced by ASCA, to calculate the phase lags and coherence between different energy…
The detection of X-ray narrow spectral features in the 5-7 keV band is becoming increasingly more common in AGN observations, thanks to the capabilities of current X-ray satellites. Such lines, both in emission and in absorption, are mostly…
Accreting black holes are thought to swallow matter in the form of a disk and a hot cloud of plasma that glows brightly in X-rays, known as the corona. The X-ray emitting region is far too small to be directly imaged, but rapid variability…
Accreting supermassive black holes at the centres of galaxies are the engine of active galactic nuclei (AGN). X-ray light curves of unabsorbed AGN show dramatic random variability on timescales ranging from seconds to years. The power…
Quantities characterizing temporal property, e.g. power density, coherence, and time lag, can be defined and calculated directly in the time domain without using the Fourier transformation. Spectral hardness, variability duration, and…
Thermal reverberation in accretion discs of active galactic nuclei is thought to be the reason of the continuum UV/optical time lags seen in these sources. Recently, we studied thermal reverberation of a standard Novikov-Thorne accretion…
We present the results from a combined study of the average X-ray spectral and timing properties of 14 nearby AGN. For 11 of the sources in the sample, we used all the available data from the RXTE archive, which were taken until the end of…
In photometric observations, the flux averaged over the preset exposure time is usually used as the representation of an object's true flux at the middle of the exposure interval. For the study of transients and variables, it is also the…