3.16 Tesis doctorado

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Browsing 3.16 Tesis doctorado by Subject "523.112"

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    Characterisation of compact stellar systems in the Coma cluster of galaxies
    (2021) Ángel Ángel, Simón Andrés; Puzia, Thomas H.; Tissera, Patricia; Goudfrooij, Paul; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    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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    Redshift-space distortions with split densities
    (2021) Paillas Villavicencio, Enrique; Padilla, Nelson; Pontificia Universidad Católica de Chile. Instituto de Astrofísica
    Accurate modelling of redshift-space distortions (RSD) is challenging in the nonlinear regime for two-point statistics e.g. the two-point correlation function (2PCF). We take a different perspective to split the galaxy density field according to the local density, and cross-correlate those densities with the entire galaxy field. We demonstrate that combining a series of cross-correlation functions (CCFs) offers improvements over the 2PCF as follows: 1. The distribution of peculiar velocities in each split density is nearly Gaussian. This allows the Gaussian streaming model for RSD to perform accurately for a wide range of scales. 2. The probability distribution function of the density field at small scales is non-Gaussian, but the CCFs of split densities capture the non-Gaussianity, leading to improved cosmological constraints over the 2PCF. We can obtain unbiased constraints on the growth parameter fσ12 at the per-cent level, and Alcock-Paczynski (AP) parameters at the sub-per-cent level with the minimal scale of 15 Mpc/h. This is a ~30 per cent and ~6 times improvement over the 2PCF, respectively. 3. Baryon acoustic oscillations (BAO) are contained in all CCFs of split densities. Including BAO scales helps to break the degeneracy between the line-of-sight and transverse AP parameters, allowing independent constraints on them. We test our methodology on N-body simulations and apply it to the BOSS DR12 galaxy samples, obtaining constraints for the growth rate of structure at different redshifts.