Characterisation of compact stellar systems in the Coma cluster of galaxies

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2021
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We present the Coma Cluster Core PrOject (C3PO), a deep, high resolution and contiguous mosaic survey of the inner ⇡ 150 square arcminutes of the core of the Coma Cluster. The region was tiled by 21 HST/WFC3 pointings and was observed in F336W from the UVIS channel, and F160W from the IR channel. Using this data, and combining this with archival data in F475W and F814W taken previously in programs led by some of our team members, we study the compact stellar systems of said cluster. We separate those systems from background galaxies and foreground stars guided by a nearUV/visible/near-IR colour-colour diagram, obtaining more than 9000 objects. From our selection, we study the globular cluster luminosity function in our available bands, finding values of the turn-over magnitude of 26.2 mag for F814W, 27.3 mag for F475W, and 25.8 in F160W. We recover the blue and red GC populations found by Peng et al. [138], finding similar relative abundances and spatial distribution. We do not recover the colour distribution found by Madrid et al. [119] because their extremely red objects are not present in our data, most likely due to the inclusion of the u band. For the first time with such diagnostic power, age and metallicity are derived for distant GCs. 60% of our GC sample falls inside the range of our SSP models, finding an age-metallicity relation that does not correlate with any single colour, but is rather dependant on pairs of colours. The age and metallicity also do not correlate strongly with spatial distribution or environment. Colour-colour relations with visible (gi) colours show differences with varying environment, which may indicate differences in star formation history and chemical enrichment history. The dataset also contains a large number of UCDs, and the method can be easily expanded to also find NSCs.
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Tesis (Doctor en Astrofísica)--Pontificia Universidad Católica de Chile, 2021
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