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Letter to the Editor
The gravitationally lensed quasar Q2237+0305 in X-rays: ROSAT/HRI detection of the "Einstein Cross"
Joachim Wambsganss 1,
Hermann Brunner 1,
Sabine Schindler 2 and
Emilio Falco 3
Received 2 March 1999 / Accepted 20 April 1999
We report the first detection of the gravitationally lensed quasar Q2237+0305 in X-rays. With a ROSAT/HRI exposure of 53 ksec taken in Nov./Dec. 1997, we found a count rate of 0.006 counts per second for the combined four images. This corresponds to an X-ray flux of erg/cm2/sec and an X-ray luminosity of erg/sec (in the ROSAT energy window 0.1-2.4 keV). The ROSAT/HRI detector is not able to resolve spatially the four quasar images (maximum separation 1.8 arcsec). The analysis is based on about 330 source photons. The signal is consistent with no variability, but with low significance. This detection is promising in view of the upcoming X-ray missions with higher spatial/spectral resolution and/or collecting power (Chandra X-ray Observatory, XMM and ASTRO-E).
Key words: cosmology: observations cosmology: gravitational lensing galaxies: quasars: individual: Q2237+0305 X-rays: galaxies X-rays: general
© European Southern Observatory (ESO) 1999
Online publication: May 6, 1999