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Astron. Astrophys. 334, 789-798 (1998)

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An ASCA-ROSAT study of the distant, lensing cluster A 2390

H. Böhringer 1, Y. Tanaka 1, 2, R.F. Mushotzky 3, Y. Ikebe 1 and M. Hattori 4

1 Max-Planck-Institut für Extraterrestrische Physik, D-85748 Garching, Germany
2 Institute of Space and Astronautical Science, Sagamihara, Kanagawa 229, Japan
3 Laboratory for High Energy Astrophysics, Code 660, NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
4 Astronomical Institute, Tohoku University, Aoba Aramaki, Sendai, Japan

Received 6 August 1997 / Accepted 9 February 1998


We present the results of a combined study of ASCA and ROSAT observations of the distant cluster Abell 2390. For this cluster a gravitational arc as well as weak lensing shear have been previously discovered.

We determine the surface brightness profile and the gas density distribution of the cluster from the ROSAT PSPC and HRI data. A combined spatially resolved spectral analysis of the ASCA and ROSAT data show that the temperature distribution of the intracluster medium of A 2390 is consistent with an isothermal temperature distribution in the range 9 to 12 keV except for the central region. Within a radius of [FORMULA] kpc the cooling time is found to be shorter than the Hubble time, implying the presence of a cooling flow. In this central region we find strong evidence for a multi-temperature structure. Detailed analysis of the combined ASCA and ROSAT data yields a self-consistent result for the spectral structure and the surface brightness profile of the cluster with a cooling flow of about [FORMULA] [FORMULA] y-1 and an age of about [FORMULA] y.

From the constraints on the temperature and density profile of the intracluster gas we determine the gravitational mass profile of the cluster and find a mass of about [FORMULA] [FORMULA] within a radius of [FORMULA] Mpc. A comparison of the projected mass profiles of the cluster shows an excellent agreement between the mass determined from X-ray data and the mass determined from the models for the gravitational arc and the weak lensing results. This agreement in this object, as compared to other cases where a larger lensing mass was implied, may probably be due to the fact that A 2390 is more relaxed than most other cases for which gravitational lensing mass and X-ray mass have been compared so far.

Key words: dark matter – gravitational lensing – Galaxies: clusters: individual: A 2390 – cooling flows – X-rays: galaxies

Send offprint requests to: H. Böhringer

© European Southern Observatory (ESO) 1998

Online publication: June 2, 1998