EDP Sciences
Free access
Issue
A&A
Volume 398, Number 1, January IV 2003
Page(s) 31 - 39
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20021656


A&A 398, 31-39 (2003)
DOI: 10.1051/0004-6361:20021656

BeppoSAX observation of the cluster Abell 970

G. B. Lima Neto1, H. V. Capelato2, L. Sodré Jr.1 and D. Proust3

1  Instituto de Astronomia, Geofísica e Ciências Atmos. (IAG), Universidade de São Paulo, Brazil
2  Divisão de Astrofísica INPE/MCT, 12227-010, São José dos Campos/S.P., Brazil
3  Observatoire de Paris-Meudon, GEPI, 92195 Meudon, France

(Received 1 July 2002 / Accepted 6 November 2002)

Abstract
We report new results on the cluster of galaxies Abell 970 obtained from X-ray observation with BeppoSAX. Our analysis of the BeppoSAX MECS and LECS data in the range [0.15-10] keV reveals a mean cluster gas temperature of kT = 4.46-0.15+0.14, a metallicity of $Z =
0.31_{-0.04}^{+0.05}~Z_{\odot}$ , and an interstellar hydrogen absorption column density of $N_{\rm H} = 6.05_{-0.97}^{+1.29} \times 10^{20}$ cm -2. Moreover, we obtained azimuthally averaged radial profiles of these quantities. Our results are consistent with the hypothesis that Abell 970 has been disturbed by a past merger or by the ongoing merger process of a substructure, that put the cluster out of equilibrium. This is also demonstrated by the offset between the gas and galaxy distributions. Combining the X-ray data with a recently published analysis of new galaxy radial velocities, we conclude that a subcluster 8 arcmin to the NW is falling into Abell 970 and will merge in a few Gigayears, thus disturbing Abell 970's newly acquired equilibrium. The high $\alpha$-elements/iron ratio that we derive for this cluster supports the hypothesis of early intracluster medium enrichment by Type II supernovae.


Key words: galaxies: clusters: individual: Abell 970 -- X-rays: galaxies: clusters

Offprint request: G. B. Lima Neto, gastao@astro.iag.usp.br

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