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shortened) Results obtained from 9 X-ray observations of 3C 273 performed by ASCA are presented (for a total exposure time of about 160 000 s). The analysis and interpretation of the results is complicated by the fact that 4 of these observations were used for on-board calibration of the CCDs spectral response. The present analysis shows that, in agreement with official recommendations, a conservative systematic error (at low energies) of about 2-3 x 10**20cm-2 must be assumed when analyzing ASCA SIS data. A soft-excess, with variable flux and/or shape, has been clearly detected as well as flux and spectral variability. An anti-correlation is found between the spectral index and the flux in the 2-10 keV energy range. Fitting the data with the latest available calibration matrices, we also detect an emission line at ~5.4-5.7 keV (~6.3-6.6 keV in the quasar frame) in (only) the two observations with lowest fluxes where it is weak (EW ~ 20-30 eV), narrow and consistent with being produced by Fe K emission from neutral matter. Overall, the observations are qualitatively consistent with a variable, non-thermal X-ray continuum emission, i.e., a power law with Gamma~1.6 (possibly produced in the innermost regions of the radio-optical jet), plus underlying ``Seyfert-like features, i.e., a soft-excess and Fe K line emission due to a reflection component. When the continuum (jet) emission is in a low state, the spectral features produced by the Seyfert-like spectrum (soft-excess, iron line and possibly a steep power law plus reflection continuum) are more easily seen.
We present results from four recent Chandra monitoring observations of the jet in 3C 273 using the ACIS detector, obtained between November 2003 and July 2004. We find that the X-ray emission comes in two components: unresolved knots that are smaller
Aims. The high energy spectrum of 3C 273 is usually understood in terms of inverse-Compton emission in a relativistic leptonic jet. This model predicts variability patterns and delays that could be tested with simultaneous observations from the radio
The Fe-K line, an important physical diagnostic in the X-ray spectra of AGN, has been notoriously difficult to measure in the high-luminosity, radio-loud quasar 3C 273 (z=0.158). On the few occasions that it has been detected its intrinsic width has
A series of nine XMM-Newton observations of the radio-loud quasar 3C 273 are presented, concentrating mainly on the soft excess. Although most of the individual observations do not show evidence for iron emission, co-adding them reveals a weak, broad
We present an analysis of the rosat and asca spectra of 21 broad line AGN (QSOs) with $zsim 1$ detected in the 2-10 keV band with the asca gis. The summed spectrum in the asca band is well described by a power-law with $Gamma=1.56pm0.18$, flatter tha