Affiliation: University of Valladolid / IA
Contribution: Poster
Title: Galaxy truncations: the physically-motivated galaxy size proxy
Abstract: Low Surface Brightness (LSB) images promise to deliver an unprecedented view of one third of the sky with HST-like spatial resolution (cf. our efforts for the Euclid satellite) permitting us to have a privileged view not only of dwarf galaxies but also the massive ones. Consequently, these innovations must have many profound repercussions on extragalactic science, and as such they are revolutionising our concept of galaxy size. This is one of the few direct galaxy observables, telling us about the continuous galaxy mass assembly. We will explain how dark matter has an impact into the sizes we determine with baryonic matter, highlighting the difference between traditional indicators (effective radii) and the relevance of utilizing a physically-motivated proxy i.e. the so-called galaxy edges or truncations. We will also describe our latest results on the evolution of these LSB features at 0<z<1 (Buitrago et al. 2024). Our conclusion is that Milky Way-like galaxies decrease their sizes by a factor of 2 up to z = 1, a more dramatic size evolution that could be parametrized as (1+z)^-1 than the one derived by using effective radii. Last but not least, we will also show the synergy that we are conducting for joining together computer scientists and astronomers to apply Machine Learning techniques to millions of galaxies with human-like accuracy (Fernandez-Iglesias et al. 2024), first for Euclid but later being able to derive galaxy sizes for any dataset/survey with minimum effort via Domain Adaptation.
This contribution can be found at the Poster Hall.
Contribution: Poster
Title: A massive dark-mater-less galaxy
Abstract: NGC1277 is a massive (1.5×10^11 M_Sun) galaxy located in the Perseus Cluster. It has been catalogued as a relic cluster because of its compactness (effective radius ~1.2 kpc) and very old stellar populations that are consistent with being untouched since its formation period. It also hosts a population of only red globular clusters and bottom-heavy IMF at all radii. Recently, Comeron et al. (2023) has shown, by means of Jeans dynamical modelling, its extreme deficiency in dark matter (dark matter fraction within 5 effective radii is 0.05 at a 2 sigma confidence level). How is it possible to form such a galaxy? Is LambdaCDM at risk? We demonstrate that galaxies like this can exist without advocating any exotic explanation just as a by-product of multiple pericenter passages in its parent cluster (Contreras-Santos et al. 2024 in press). While orbiting the host halo, tidal interactions gradually strip the less bound dark matter, although this effect should be eventually noticed in the stellar component. We are conducting efforts in that direction (Buitrago et al. 2024 in prep.) using Euclid’s Early Release Observations data, whose superb depth, spatial resolution and crucially near-infrared capabilities allow us to detect low surface brightness stellar asymmetries.
This contribution can be found at the Poster Hall.