EDP Sciences
Free access
Issue A&A
Volume 490, Number 3, November II 2008
Page(s) 989 - 994
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20078730
Published online 17 September 2008



A&A 490, 989-994 (2008)
DOI: 10.1051/0004-6361:20078730

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

E. V. Fedorova1, V. I. Zhdanov1, C. Vignali2, and G. G. C. Palumbo2

1  Astronomical Observatory of Kyiv Shevchenko University, Observatorna St. 3, Kiev, UA- 04053, Ukraine
    e-mail: elena_f@mail.univ.kiev.ua; zhdanov@observ.univ.kiev.ua
2  Dipartimento di Astronomia, Università di Bologna, via Ranzani 1, 40127 Bologna, Italy
    e-mail: [cristian.vignali;giorgio.palumbo]@unibo.it

Received 25 September 2007 / Accepted 23 August 2008

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 $6\times 10^{-13}$ 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 $\Gamma=1.82_{ - 0.08}^{ + 0.07}$. The X-ray lightcurves obtained after background subtraction are compatible with the hypothesis of a stationary flux from the source.


Key words: gravitational lensing -- X-rays: general -- galaxies: quasars: general



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Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: C. Bertout

ISSN: 0004-6361 ; e-ISSN: 1432-0746
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Published by: EDP Sciences

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