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We compare the distribution of optically and Halpha (Ha) selected galaxies in the Southern half of the nearby Abell 85 (A85) cluster with the recently discovered X-ray filament (XRF). We search for galaxies where star formation (SF) may have been triggered by interactions with intracluster gas or tidal pressure due to the cluster potential when entering the cluster. Our analysis is based on images obtained with CFHT MegaPrime/MegaCam (1x1 deg2 field) in four bands (ugri) and ESO 2.2mWFI (38x36 field) in a narrow band filter corresponding to the redshifted Halpha (Ha) line and in a broad R-band filter. The LFs are estimated by statistically subtracting a reference field. Background contamination is minimized by cutting out galaxies redder than the observed red sequence in the g-i vs. i colour-magnitude diagram. The galaxy distribution shows a significantly flattened cluster, whose principal axis is slightly offset from the XRF. The analysis of the broad band LFs shows that the filament region is well populated. The filament is also independently detected as a gravitationally bound structure by the Serna & Gerbal hierarchical method. 101 galaxies are detected in Ha, among which 23 have spectroscopic redshifts in the cluster, 2 have spectroscopic redshifts higher than the cluster and 58 have photometric redshifts that tend to indicate that they are background objects.The 23 galaxies with spectroscopic redshifts in the cluster are mostly concentrated in the South part of the cluster and along the filament. We find a number of galaxies showing evidence for SF in the XRF, and all our results are consistent with the previous hypothesis that the XRF in A85 is a gravitationally bound structure made of groups falling on to the main cluster.
Abell 3376 is a merging cluster of galaxies at redshift z=0.046, famous mostly for its giant radio arcs, and shows an elongated and highly substructured X-ray emission, but has not been analysed in detail at optical wavelengths. We have obtained wide
Based on a VLA HI-imaging through the total volume of the cluster Abell 85, we compare the distribution of HI-rich and HI deficient late type galaxies with the intra cluster medium (ICM) drawn by the X-ray emission.
Several scenarios explaining how filaments are formed can be found in literature. In this paper, we analyzed the observations of an active region filament and critically evaluated the observed properties in the context of current filament formation m
We report the observation of the Intra-Cluster Medium (ICM) of Abell 85 by the X-ray satellite BeppoSAX. We have both analysed the spectrum obtained in the central 8 arcmin circular region centred on the Very Steep Spectrum Radio Source (VSSRS) and t
For the first time, we explore the dynamics of the central region of a galaxy cluster within $r_{500}sim 600h^{-1}$~kpc from its center by combining optical and X-ray spectroscopy. We use (1) the caustic technique that identifies the cluster substruc