相关论文: Rapidly variable Fe K$\alpha$ line in NGC 4051

The X-ray spectra of two intermediate type Seyfert galaxies are investigated using ASCA observations separated by more than a year. Both NGC 4388 and ESO 103-G35 exhibit strong, narrow Fe K alpha line emission and absorption by cold neutral…

Direct time-resolved spectral fitting has been performed on continuous RXTE monitoring of seven Seyfert 1 galaxies in order to study their broadband spectral variability and Fe K alpha variability characteristics on time scales of days to…

On 9-11 May 1998, the highly-variable, low luminosity Seyfert 1 galaxy NGC4051 was observed in an unusual low flux state by BeppoSAX (Guainazzi et al. 1998) RXTE and EUVE. We present fits of the 4-15 keV RXTE spectrum and BeppoSAX MECS…

We present detailed time-averaged X-ray spectroscopy in the 0.5--10 keV band of the Seyfert~1.9 galaxy NGC 2992 with the Suzaku X-ray Imaging Spectrometers (XIS). We model the complex continuum in detail. There is an Fe K line emission…

We have performed systematic studies of narrow Fe-K line (6.4 keV) flux variability and Ni-K line intensity for Seyfert galaxies, using {\em Suzaku} and {\em XMM-Newton} archival data. Significant Fe-K line variability of several tens…

We present strong evidence for variability of the flux of the iron K$\alpha$ emission line in the Seyfert 1 galaxy, NGC 3516. Two ASCA observations, separated by $\sim 1$~yr, showed a marked decrease in continuum flux by $\sim 60$~per cent.…

We report results from a 2007 Suzaku observation of the Seyfert 1 AGN NGC 4593. The narrow Fe K alpha emission line has a FWHM width ~4000 km/s, indicating emission from >~ 5000 Rg. There is no evidence for a relativistically broadened Fe K…

We report on the results from a large observational campaign on the bare Seyfert galaxy Ark 120, jointly carried out in 2014 with XMM-Newton, Chandra, and NuSTAR. The fortunate line of sight to this source, devoid of any significant…

It has been suggested that X-ray observations of rapidly variable Seyfert galaxies may hold the key to probe the gas orbital motions in the innermost regions of accretion discs around black holes and, thus, trace flow patterns under the…

NGC 4051 is a nearby (16.7 Mpc), Narrow Line Seyfert 1 galaxy (NLS1), which has a low black hole mass of $10^6$ M$_{\odot}$. It is also known for its rapid X-ray variability, on timescales of kilo-seconds and has a complex, multi component…

We report the detection of a narrow Fe-K emission line in the Seyfert 1 galaxy NGC 5548 with the Chandra High-Energy Transmission Gratings. In the galaxy frame we measure a center energy of 6.40 \pm 0.03 keV, a FWHM of 4515 (+3525,-2645)…

We present the results of the Suzaku observation of the Seyfert 2 galaxy NGC 4507. This source is one of the X-ray brightest Compton-thin Seyfert 2s and a candidate for a variable absorber. Suzaku caught NGC 4507 in a highly absorbed state…

We present the first X-ray monitoring observations of the X-ray bright FRI radio galaxy NGC6251 observed with RXTE for 1 year. The primary goal of this study is to shed light on the origin of the X-rays, by investigating the spectral…

We present simultaneous observations by EUVE, ASCA, and RXTE of the type~1 Seyfert galaxy NGC 5548. These data indicate that variations in the EUV emission (at $\sim 0.2 $keV) appear to lead similar modulations in higher energy ($\ga 1…

We report the results from a Chandra TOO observation of the low-luminosity Narrow Line Seyfert 1 galaxy NGC 4051, obtained during a 6-week duration low-flux state in 2001 February. During the Chandra observation, the 2-10 keV source flux…

NGC 1566 is a changing look AGN known to exhibit recurrent X-ray outbursts with each lasting for several years. The most recent X-ray outburst is observed on 2018, with a substantial increase of 2--10 keV flux by a factor of ~24 than the…

We report on some results from a three-year program of RXTE observations of 4 Seyfert galaxies: NGC 4051, NGC 5548, MCG-6-30-15 and NGC 5506. We focus here on color-color and color-flux diagrams obtained using the count-rates of the PCA…

We present the imaging and spectroscopic analysis of the combined Chandra ACIS-S observations of the Compton-thick Seyfert 2 galaxy NGC 4945. We performed a spatially-resolved spectroscopy of the circumnuclear environment of the source,…

BeppoSAX observed the low-luminous Seyfert 1 Galaxy NGC4051 in a ultra-dim X-ray state. The 2-10 keV flux (1.26 x 10^{-12} erg/cm^2/s) was about 20 times fainter than its historical average value, and remained steady along the whole…

There is growing evidence for the presence of blueshifted Fe K absorption lines in a number of radio-quiet AGNs and QSOs. These may be fundamental to probe flow dynamics near supermassive black holes. Here we aim at verifying and better…