相关论文: RXTE observations of Seyfert-2 galaxies: evidence …

We investigate the X-ray spectra of the type-2 Seyfert galaxies NGC 7172 and ESO 103-G35, using BeppoSAX observations, separated by approximately one year. We find that the X-ray spectra of both NGC 7172 and ESO 103-G35 can be well fitted…

We present results from RXTE data obtained during a systematic monitoring program of four Seyfert galaxies (NGC5548, NGC5506, MCG-6-30-15 and NGC4051). We studied the variability of three hardness ratios derived from the light curves in…

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…

A broad band X-, gamma-ray spectral study of the Seyfert 2 galaxy NGC 7172 is presented. We use our ASCA observations from May 1995 and combine these with the CGRO OSSE data from March 1995. The only Seyfert 2 galaxy previously to have been…

We present evidence of flux variability, on both short (hours) and long (months) time scales of the Seyfert 2 galaxy NGC 7172. These results are based on the ASCA observation of NGC 7172 performed on May 1996. The source was detected at a…

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…

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…

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…

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…

We present a combined, non-simultaneous, ASCA GIS and CGRO OSSE spectrum of the Seyfert 2 galaxy, NGC 7172, and make broad band spectral fits. The only Seyfert 2 galaxy previously studied over such a broad band is NGC 4945. We find that the…

We report broad band (0.1-200 keV) X-ray observations, made by BeppoSAX, of a sample of bright Seyfert 2 galaxies: NGC7172, NGC2110, NGC4507, Mkn 3 and NGC7674. These spectra provide a better understanding of the effects of X-ray…

The broad band 0.1-200 keV spectra of a sample of 5 Seyfert 2 galaxies (NGC 7172, Mkn 3, NGC 2110, NGC 4507 and NGC 7674) have been measured within the first year of the $BeppoSAX$ Core program. All sources have been detected up to \~ 100…

We have analyzed the two longest (elapsed time > 3 days) BeppoSAX observations of the X-ray brightest Seyfert galaxy, NGC 4151, to search for spectral variability on time-scales from a few tens of ksec to years. We found in both cases…

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 report on observations of the narrow line Seyfert galaxy NGC 5506 with the Rossi X-ray TIming Explorer. The observations cover a time interval of ~1000 days during which the source showed strong flux and spectral variability. The…

We report results from a Suzaku observation of the narrow-line Seyfert 1 NGC 4051. During our observation, large amplitude rapid variability is seen and the averaged 2--10 keV flux is 8.1x10^-12 erg s^-1 cm^-2, which is several times lower…

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…

Preliminary results of the RXTE observation of the Seyfert 2 Galaxy NGC4507 are presented. The observed broadband [4-100 keV] spectrum is intrinsically hard (Gamma = 1.2); an iron line is detected with a relatively high equivalent width (EW…

We present the analysis of X-ray spectral varability made on a sample of 7 Seyfert 1 bright galaxies, using XMM-Newton data. From the "XMM-Newton Science Archive" we selected those bright Seyfert 1 showing one or more prominent flares in…

We present an analysis of the long RXTE observation of the Seyfert~1 galaxy MCG-6-30-15, taken in July 1997. Our results show that the behaviour is complicated. We find clear evidence from colour ratios and direct spectral fitting that…