Q2237+0305 in X-rays: spectra and variability with XMM-Newton

Abstract

Aims: X-ray observations of gravitationally lensed quasars may allow us to probe the inner structure of the central engine of a quasar. Observations of Q2237+0305 (Einstein Cross) in X-rays may be used to constrain the inner structure of the X-ray emitting source.
Methods: Here we analyze the XMM-Newton observation of the quasar in the gravitational lens system Q2237+0305 taken during 2002. Combined spectra of the four images of the quasar in this system were extracted and modelled with a power-law model. Statistical analysis was used to test the variability of the total flux.
Results: The total X-ray flux from all the images of this quadruple gravitational lens system is 6× 10^-13 erg/(cm² s) in the range 0.2-10 keV, showing no significant X-ray spectral variability during almost 42 ks of the observation time. Fitting of the cleaned source spectrum yields a photon power-law index of Γ=1.82 _{- 0.08} ^{+ 0.07}. The X-ray lightcurves obtained after background subtraction are compatible with the hypothesis of a stationary flux from the source.

Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.