I am interested in understanding how galaxies formed and evolved. Currently, my research focuses on the evolution of galaxies in clusters and proto-clusters. I have a broad range of interests, including AGN, large-scale structures, and cosmology.
In this image from Wilson+08, we can see a high-z galaxy cluster and its red galaxies. Why should we look at them? We must look at high-zs to understand how these objects formed and evolved. I am interested in knowing more about these monsters of the cosmos and their galaxies! In Werner et al. (2021), we used the GOGREEN and GCLASS data to investigate the infall region of galaxy clusters at z~1. We found that the galaxies in the infall region are very different from field and cluster galaxies. We also found that most galaxies quenched before entering the main cluster halo, and satellite quenching was not important at z~1. This effect is stronger for more massive galaxies; most quench before arriving in the cluster. The main physical mechanism is unclear, and it can be due to preprocessing in groups, AGN or other mechanisms. We discuss it more in the paper.
Free-floating stars in the core of galaxy proto-clusters
Free-floating stars within galaxy clusters are thought to result from gravitational tides and galaxy interactions that rip stars away from their parent galaxies. Within the cosmological paradigm of hierarchical structure formation, such interactions accumulate over time which suggests that the amount of intracluster stars should be negligible in young proto-clusters and grow to around a quarter of the stellar mass in the oldest, most mature clusters. In contrast to these theoretical expectations, we report on the detection of copious intracluster stars within two proto-clusters at a redshift of 2. The distribution of stars in these protoclusters is similarly extended as in nearby mature clusters. This suggests that intracluster stars are a generic feature of massive dark matter halos, regardless of when these halos are observed. This paper was recently accepted by MNRAS (Werner et al. 2023).
S-PLUS galaxy clusters and groups catalogue with PzWav
We used the S-PLUS survey data (Mendes de Oliveira et al. 2019) and the PzWav technique to build a galaxy cluster catalogue (Werner et al. 2022). The S-PLUS data take advantage of 12 optical filters, which return precise photometric redshift estimates. Using simulations, we show that the photo-z precision influences cluster detections. We also used simulations to find the best parameters and check the purity and completeness levels we could reach. More information about the catalogue can be found in Werner et al. (2022). The catalogue is available on GitHub.
Using simulations, we can visualise the detections of clusters and groups in different redshifts for different mass ranges. In the video, we show a small area of the sky, and it is possible to see the clusters appearing in the smoothed images. More massive clusters are more prominent in the video. We added the log of the mass in solar masses, the redshift of each cluster, and the redshift of the slice in the top right.
Analyzing Galaxy Proto-clusters at 1.3<z<2.9
Previous works show that galaxies in clusters at z<1.5 are evolving passively since a major part of the mass was already accreted (Wylezalek et al. 2014). On the other hand, clusters at z~1.5 have a considerable star-forming population (Brodwin et al. 2013, Snyder et al. 2012). Additionally, Wylezalek et al. (2014) showed that clusters at 1.5<z<3.0 have significant star formation. This is evidence that the physical processes behind the evolution of galaxies at high redshifts are different from low redshifts. Thus, to understand which physical processes triggered this star formation, it is crucial to study clusters at z>1.5. Our main goal is to quantify properties of proto-cluster galaxies and connect them with different physical processes that are responsible for quenching or triggering star formation in galaxies. We are currently analysing 20 galaxy proto-clusters at 1.3<z<3.0.