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Astron. Astrophys. 349, 97-107 (1999)

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A multi-wavelength analysis of the cluster of galaxies ABCG 194

E. Nikogossyan 1, F. Durret 2,3, D. Gerbal 2,3 and F. Magnard 2

1 Byurakan Observatory, Aragatsotn Province, 375433, Armenia
2 Institut d'Astrophysique de Paris, CNRS, 98bis Bd Arago, F-75014 Paris, France
3 DAEC, Observatoire de Paris, Université Paris VII, CNRS (UA 173), F-92195 Meudon Cedex, France

Received 10 May 1999 / Accepted 19 July 1999

Abstract

We present a morphological and structural analysis of the Richness zero cluster ABCG 194, known as a "linear cluster". This study is based on a catalogue of 97 galaxies with B magnitudes and redshifts belonging to the cluster, a ROSAT PSPC image and radio data.

We show that the overall large scale structure is rather smooth and comparable at optical and X-ray wavelengths. The cluster is elongated along PA [FORMULA]; however it appears as "linear" when taking into account only galaxies in the very central part (the axial ratio varies from 0.2 in the central region to 0.8 for a larger region). We have obtained the galaxy density profile and despite the very low X-ray emission the X-ray emitting gas density profile. We have estimated the X-ray gas and dynamical masses up to the limiting radius [FORMULA] of the PSPC image (respectively [FORMULA] and 8 1013 [FORMULA]) and the stellar mass up to [FORMULA] and to 3 Mpc (3 [FORMULA] and 7.5 1012 [FORMULA]).

At smaller scales, the analysis of both positions and velocities reveals the existence of several groups but which are not strongly linked dynamically; however a main structure with a nearly gaussian velocity distribution is exhibited. The velocity dispersion is small ([FORMULA] = 360 km s-1). A wavelet analysis of the X-ray image reveals no large scale substructures. Small scale X-ray sources are detected, mainly corresponding to individual galaxies; we give an estimate of their luminosities. The lack of strong substructuring suggests that ABCG 194 is overall a relaxed cluster.

ABCG 194 is a poor and cold cluster; we compare how its characteristics fit into various correlations found in the literature, but generally for richer/hotter clusters, such as the [FORMULA]-[FORMULA], [FORMULA]-[FORMULA], [FORMULA]-[FORMULA] relations or the ratios of various kinds of masses.

Key words: galaxies: clusters: general – galaxies: clusters: individual: ABCG 194

Send offprint requests to: F. Durret (durret@iap.fr)

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© European Southern Observatory (ESO) 1999

Online publication: August 25, 1999
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