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Astron. Astrophys. 353, 498-506 (2000)

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Beppo SAX observations of two high redshift clusters of galaxies: RXJ 0152.7-1357 and MS 2053.7-0449

R. Della Ceca 1, R. Scaramella 2, I.M. Gioia 3,4, P. Rosati 5, F. Fiore 2,6 and G. Squires 7,8

1 Osservatorio Astronomico di Brera, via Brera 28, 20121 Milano, Italy
2 Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Italy
3 Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822, USA
4 Istituto di Radioastronomia del CNR, via Gobetti 101, 40129 Bologna, Italy
5 European Southern Observatory, 85748 Garching bei München, Germany
6 BeppoSAX Science Data Center, via Corcolle 19, 00131 Roma, Italy
7 Center for Particle Astrophysics, UC Berkeley, 301 Le Conte Hall, Berkeley, CA, USA
8 Caltech Astronomy M/S 105-24, 1200 E. California Blvd., Pasadena, CA, USA

Received 4 August 1999 / Accepted 20 October 1999


We present X-ray observations of two high redshift clusters of galaxies carried out with the Beppo SAX satellite. One cluster, RXJ 0152.7-1357 at [FORMULA], was selected from the ROSAT Deep Cluster Survey sample, as one of the most X-ray luminous systems known at [FORMULA]. The optical and ROSAT-PSPC data show a complex morphology with at least two cores. Our SAX observations yield a gas temperature [FORMULA] keV and a metallicity [FORMULA], with a prominent iron [FORMULA] line. The second cluster, MS 2053.7-0449 at [FORMULA], was selected from the EMSS sample. Given the poor statistics no constraints on the metallicity can be derived from the present data. Large uncertainties are associated to the gas temperature ([FORMULA] keV), which has been obtained after fixing the abundance to 0.3 solar. Combining these results with those obtained for similarly high redshift ([FORMULA]) clusters of galaxies with broad band X-ray spectra, we discuss the high redshift [FORMULA] relationship. The data can easily be accommodated with a non-evolving (or mildly evolving) [FORMULA] relation, a result which, when combined with the little observed evolution in the bulk of the X-ray cluster population, gives support to low [FORMULA] cosmological models.

Key words: galaxies: clusters: individual: MS 2053.7-0449 – galaxies: clusters: individual: RXJ 0152.7-1357 – cosmology: observations – X-rays: galaxies

Send offprint requests to: R. Della Ceca (rdc@brera.mi.astro.it)

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© European Southern Observatory (ESO) 2000

Online publication: December 17, 1999