Related papers: Revealing structure and evolution within the coron…
We report on X-ray flares that were observed from the active galactic nucleus I Zwicky 1 (I Zw 1) in 2020 January by the NuSTAR and XMM-Newton observatories. The X-ray spectrum is well-described by a model comprised of the continuum…
The short-term spectral variability of the narrow-line Seyfert 1 galaxy I Zwicky 1 (I Zw 1) as observed in an 85 ks XMM-Newton observation is discussed in detail. I Zw 1 shows distinct modes of variability prior to and after a flux dip in…
The innermost regions of accretion disks around black holes are strongly irradiated by X-rays that are emitted from a highly variable, compact corona, in the immediate vicinity of the black hole. The X-rays that are seen reflected from the…
Models of X-ray reverberation from extended coronae are developed from general relativistic ray tracing simulations. Reverberation lags between correlated variability in the directly observed continuum emission and that reflected from the…
The narrow-line Seyfert 1 galaxy 1H0707-495 has previously been identified as showing time lags between flux variations in the soft- (0.3-1 keV) and medium-energy (1-4 keV) X-ray bands that oscillate between positive and negative values as…
X-ray reverberation, where light-travel time delays map out the compact geometry around the inner accretion flow in supermassive black holes, has been discovered in several of the brightest, most variable and well-known Seyfert galaxies. In…
Understanding disc-corona geometry through X-ray reverberation variability studies in Seyfert galaxies is crucial, yet our knowledge mostly relies on flux-averaged mean spectral analysis. In this study, we investigate the origin of the…
We present results based on an XMM-Newton observation of the prototype narrow-line Seyfert 1 galaxy I Zw 1 performed in June 2002. The 0.6-12 keV spectrum is well described by a steep power-law (Gamma\sim 2.3) and a weak soft blackbody…
The X-ray spectra of the narrow line Seyfert 1 galaxy, 1H 0707-495, obtained with XMM-Newton, from time periods of varying X-ray luminosity are analysed in the context of understanding the changes to the X-ray emitting corona that lead to…
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…
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 X-ray emission from active galactic nuclei (AGN) is highly variable. Measurements of time lags (characterised by lag spectra) between variability in the light curves in energy bands corresponding to directly observed continuum emission…
X-ray reverberation, which exploits the time delays between variability in different energy bands as a function of Fourier frequency, probes the structure of the inner accretion disks and X-ray coronae of active galactic nuclei. We present…
We present the second XMM-Newton observation (85 ks) of the narrow-line Seyfert 1 galaxy (NLS1) I Zw 1 and describe its mean spectral and timing characteristics. On average, I Zw 1 is ~35 per cent dimmer in 2005 than in the shorter (20 ks)…
MCG-6-30-15 is one of the most observed Narrow Line Seyfert 1 galaxies in the X-ray band. In this paper we examine the X-ray time lags in this source using a total of 600 ks in observations (440 ks exposure) taken with the XMM-Newton…
We develop a physically motivated, spherical corona model to investigate the frequency-dependent time lags in AGN. The model includes the effects of Compton up-scattering between the disc UV photons and coronal electrons, and the subsequent…
We analyse the X-ray time-lags in the Narrow Line Seyfert 1 (NLS1) galaxy PG 1244+026 ($M_{\rm BH}\sim 10^7 M_{\rm sun}$, $L/L_{\rm Edd}\sim 1$). The time delay between the soft (0.3--0.7~keV) and harder (1.2--4.0~keV) variations shows…
X-ray inter-band time lags are observed during the outbursts of black hole X-ray binaries (BHXRBs). Timing analysis of fast variability in low Fourier frequency bands shows that high-energy photons lag behind low-energy photons, a…
A triggered 140 ks XMM-Newton observation of the narrow-line Seyfert 1 (NLS1) Mrk 335 in December 2015 caught the active galaxy at its lowest X-ray flux since 2007. The NLS1 is relatively quiescent for the first ~120 ks of the observation…
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…