Abstract
ABSTRACT We analyse a sample of 12 galaxy clusters, from the Kapteyn IAC WEAVE INT Cluster Survey (KIWICS) looking for dwarf galaxy candidates. By using photometric data in the r and g bands from the Wide Field Camera (WFC) at the 2.5-m Isaac Newton Telescope (INT), we select a sample of bright dwarf galaxies (M$_r\, \le$ −15.5 mag) in each cluster and analyse their spatial distribution, stellar colour, and as well as their Sérsic index and effective radius. We quantify the dwarf fraction inside the R200 radius of each cluster, which ranges from ∼0.7 to ∼0.9. Additionally, when comparing the fraction in the inner region with the outermost region of the clusters, we find that the fraction of dwarfs tends to increase going to the outer regions. We also study the clustercentric distance distribution of dwarf and giant galaxies (M$_r\, \lt $ −19.0 mag), and in half of the clusters of our sample, the dwarfs are distributed in a statistically different way as the giants, with the giant galaxies being closer to the cluster centre. We analyse the stellar colour of the dwarf candidates and quantify the fraction of blue dwarfs inside the R200 radius, which is found to be less than ∼0.4, but increases with distance from the cluster centre. Regarding the structural parameters, the Sérsic index for the dwarfs we visually classify as early-type dwarfs tends to be higher in the inner region of the cluster. These results indicate the role that the cluster environment plays in shaping the observational properties of low-mass haloes.
Highlights
Galaxy clusters are the largest and gravitationally bound structures in the Universe
We considered as background objects those galaxies located more than 1.5-σ above the linear relation in the Mr − μe defined by the cluster members
We analysed a set of twelve nearby clusters from the Kapteyn IAC WHT Enhanced Area Velocity Explores (WEAVE) Isaac Newton telescope (INT) Cluster Survey (KIWICS) survey, studying the properties of the dwarf population in each cluster for galaxies as faint as a total r-band absolute magnitude, Mr = -15.5 mag
Summary
Galaxy clusters are the largest and gravitationally bound structures in the Universe They cover a wide range of masses ranging from ∼ 1012 − 1015 M , from small groups with tens of galaxies to clusters with thousands of members, there is not a sharp line between them. We might still have some contamination of foreground and background galaxies even applying a colour cut, as they can have a g - r < 1.0 mag so we performed a second cut using the surface brightness-magnitude plane (similar to Venhola et al 2018) To perform this selection, all the clusters of our sample were analysed together (bottom panel; Fig.4 ) in order to have a robust number of spectroscopically confirmed (and not confirmed) galaxy members. The fainter objects that were included in this group were those that did not have a uniform colour, that is, with some characteristics such as blue spots
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