Related papers: Bulk Comptonization: new hints from the luminous b…
Recently, blazar 4C +27.50 was found to be flaring in gamma-rays since its detection with Fermi-LAT in 2008. For the first time, a dedicated temporal and spectral study of the blazar 4C +27.50 has been performed in this work to understand…
We present the X-ray variability properties of the X-ray and TeV bright blazar Mrk 421 with a ~60 ks long XMM-Newton observation performed on November 9-10, 2005. The source experienced a pronounced flare, of which the inter-band time lags…
We have observed with XMM-Newton four radiatively efficient active type 1 galaxies with black hole masses < 10^6 Msun, selected optically from the SDSS. We show here that their soft X-ray spectrum exhibits a soft excess with the same…
We observed with the NuSTAR satellite 3 blazars at z>2, detected in gamma-rays by Fermi/LAT and in the soft X-rays, but not yet observed above 10 keV. The flux and slope of their X-ray continuum, together with Fermi/LAT data allows us to…
In paper 1 (Cheng et al. 2001) we have shown that the soft X-ray spectra of two types of Seyfert 1 galaxies statistically vary differently with increasing intensity. In order to understand how the spectrum of blazars changes, the spectral…
This paper reports the results of Suzaku observation of the spectral variation of the black hole binary LMCX-1 in the soft state. The observationwas carried out in 2009 from July 21 to 24. the obtained net count rate was $\sim$30 counts…
We present an update of 3C 273's database hosted by the ISDC, completed with data from radio to gamma-ray observations over the last 10 years. We use this large data set to study the multiwavelength properties of this quasar,especially…
We have carried out a systematic analysis of the nearby (z=0.0279) active galaxy Zw 229.015 using multi-epoch, multi-instrument and deep pointed observations with XMM-Newton, Suzaku, Swift and NuSTAR. Spectral and temporal variability are…
The X-ray emission from blazars has been widely investigated using several space telescopes. In this work, we explored statistical properties of the X-ray variability in the blazars S5 0716+714, OJ 287, Mkn 501 and RBS 2070 using the…
The theoretical predictions of the converging inflow, or Bulk-Motion Comptonization model are discussed and some predictions are compared to X- and gamma-ray observations of the high/soft state of Galactic black hole candidate XTE…
We present an analysis of a pair of Suzaku spectra of the soft X-ray background (SXRB), obtained from pointings on and off a nearby shadowing filament in the southern Galactic hemisphere. Because of the different Galactic column densities…
Strong soft X-ray emission called soft X-ray excess is often observed in luminous active galactic nuclei (AGN). It has been suggested that the soft X-rays are emitted from a warm ($T=10^6\sim10^7\ \rm{K}$) region that is optically thick for…
We present results from the analysis of the two EXOSAT observations of the low mass X-ray binary (LMXRB) 4U1957+11. The 1-20keV spectrum of the source is best fitted by a power law model with exponential cutoff, that provides an…
We study the variability properties at radio frequencies of the jets thought to be typical of Active Galactic Nuclei, i.e. bulk Lorentz factor \Gamma ~ 10, and incoherent synchrotron emission. We assume that the radiating electrons are…
The synchrotron reflection scenario recently proposed to explain $\gamma$-ray flares observed from blazar jets is studied. Our analysis takes into account the angular distribution of the beamed radiation, the finite extent of the scattering…
The active galactic nucleus 4C +28.07 is a flat spectrum radio quasar, one of the brightest at $\gamma$-ray energies. We study its multi-wavelength emission by analysing $\sim12.3$ years of \textit{Fermi-LAT} data in the $\gamma$-ray band…
We report on a \textit{NuSTAR} and \textit{Swift}/XRT observation of the newly discovered X-ray transient MAXI J1820+070. \textit{Swift}/XRT and \textit{NuSTAR} have concurrently observed the newly detected source on 14 March 2018. We have…
The Type I Seyfert galaxy Markarian 509 was observed with Suzaku in 2010 November, for a gross time span of 2.2 days. Timing and spectral properties of the 0.5-45 keV X-rays, detected with the XIS and HXD, consistently revealed the presence…
Blazars radiate from relativistic plasma jets with bulk Lorentz factors {\Gamma} ~ 10, closely aligned along our line of sight. In a number of blazars of the Flat Spectrum Radio Quasar type such as 3C 454.3 and 3C 279 gamma-ray flares have…
We report on the XMM-Newton observation of the Be/neutron star X-ray binary system RX J0146.9+6121, a long period (~ 23 m) pulsar in the NGC 663 open cluster. The X-ray luminosity decreased by a factor two compared to the last observation…