相关论文: Variable X-ray reflection from 1H~0419--577

We present a flux-resolved X-ray analysis of the dwarf Seyfert 1.8 galaxy NGC 4395, based on three archival $XMM-Newton$ and one archival $NuSTAR$ observations. The source is known to harbor a low mass black hole ($\sim 10^4- {\rm a~…

We have monitored the Seyfert galaxy NGC 3227 with the Rossi X-ray Timing Explorer (RXTE) since January 1999. During late 2000 and early 2001 we observed an unusual hardening of the 2-10 keV X-ray spectrum which lasted several months. The…

We present simultaneous XMM-Newton and NuSTAR observations of the `bare' Seyfert 1 galaxy, Ark 120, a system in which ionized absorption is absent. The NuSTAR hard X-ray spectral coverage allows us to constrain different models for the…

We present two new NuSTAR observations of the narrow line Seyfert 1 (NLS1) galaxy Mrk 766 and give constraints on the two scenarios previously proposed to explain its spectrum and that of other NLS1s: relativistic reflection and partial…

We report on the X-ray spectral variability of the Seyfert 1 galaxy NGC 4051 observed with the Rossi X-ray Timing Explorer (RXTE) during a 1000 day period between May 1996 and March 1999. The spectra were obtained as part of monitoring…

We report on a 50 ks observation of the bright Seyfert 1 galaxy MCG--6-30-15 with the Rossi X-ray Timing Explorer. The data clearly show the broad fluorescent iron line (equivalent width ~ 250 eV), and the Compton reflection continuum at…

We present a detailed analysis of the XMM-Newton observations of five narrow-line Seyfert 1 galaxies (NLS1s). They all show very soft continuum emission in the X-ray band with a photon index of $\Gamma\gtrsim 2.5$. Therefore, they are…

The 1.5 Seyfert galaxy NGC 3227 has been observed by several X-ray missions. We carried out a combined analysis of the data obtained by more recent major observations of the source: two observations performed by XMM-Newton in 2000 and 2006…

A sample of narrow-line (NLS1) and broad-line Seyfert 1 (BLS1) galaxies observed with Suzaku is presented. The final sample consists of 22 NLS1s and 47 BLS1s, for a total of 69 AGN that are all at low redshift (z<0.5) and exhibit low host…

Active galactic nuclei (AGNs) are known to be variable across all wavelengths. Significant observational efforts have been invested in the last decade in studying their ultraviolet (UV) and optical variability. Long and densely sampled,…

We present spectroscopic X-ray data of two candidate ultra-compact X-ray binaries: 4U~0614+091 and 4U~1543$-$624. We confirm the presence of a broad O VIII Ly$\alpha$ reflection line (at $\approx18\ \AA$) using {\it XMM-Newton} and {\it…

Probing the physics of the accretion flow around active galactic nuclei (AGN) is crucial to understanding their emission mechanisms as well as being able to constrain the geometrical and variability properties of the different regions…

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…

We report on the first detection of hard X-ray photons (E>2.5 keV) in the X-ray transient Narrow-Line Seyfert 1 galaxy WPVS 007 which was the AGN with the softest X-ray spectrum during the ROSAT All-Sky Survey. The AGN is clearly detected…

In this work, the analysis of multi-epoch (1995-2010) X-ray observations of the Seyfert 1 galaxy H0557-385 is presented. The wealth of data presented in this analysis show that the source exhibits dramatic spectral variability, from a…

A fraction of active galactic nuclei (AGN) exhibit dramatic variability, which is observed on timescales down to minutes in the X-ray band. We introduce the case study of 1H 1934-063 (z = 0.0102), a Narrow-line Seyfert 1 (NLS1) among the…

We present a systematic investigation of X-ray spectral variability of Seyfert 1 galaxies using a ``spectral-ratio model fitting'' technique, which we developed to estimate contribution of the putative clumpy absorbers to the spectral…

X-ray reflection generates much of the spectral complexity in the X-ray spectra of AGN. It is argued that strong relativistic blurring of the reflection spectrum should commonly be expected from objects accreting at a high Eddington rate.…

Aims: Active Galactic Nuclei are known to be variable throughout the electromagnetic spectrum. An energy domain poorly studied in this respect is the hard X-ray range above 20 keV. Methods: The first 9 months of the Swift/BAT all-sky survey…

This paper combines data from the three preceding papers in order to analyze the multi-waveband variability and spectral energy distribution of the Seyfert~1 galaxy NGC~4151 during the December 1993 monitoring campaign. The source, which…