Exploring the connection between large-scale structure and galactic conformity in low-mass galaxies

• Grant number: 25/07340-9
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2025
• End date: April 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Laerte Sodré Junior
• Grantee: Daniela Fernanda Palma Palma
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 11/51680-6 - Exploring the universe: from the galaxies formation to Earth-like planets with the Giant Magellan Telescope, AP.ESP

Abstract

This project aims to explore the outskirts of galaxy groups and clusters as intermediate density regions, contributing to our understanding of galaxy evolution in these environments and their connection to the large-scale structure (LSS). The motivation behind focusing on these outskirts is closely tied to upcoming surveys that will extend coverage beyong massive structures, reaching the low-mass regime of neighboring galaxies. Filaments and streams in these regions may play a crucial role in shaping galax properties before they enter dense environments. In particular, they could influence the large-scale conformity signal and the star formation activity of low-mass galaxies. Identifying low-mass central galaxies with respect to filamentary structures can help clarify the origin of the strong signal these galaxies exhibit. For instance, simulations such as IllustrisTNG300 and MDPL2-SAG reveal that a significant fraction of star-forming (SF) galaxies persist in the outskirts massive systems, appearing largely unaffected by their massive neighbors. In contrast, a smaller population of quenched galaxies in these peripheries exhibits strong environmental imprints. One possible explanation is that SF galaxies sustain their star formation by accreting material from filaments or streams. Alternatively, filaments may act as "protective" structures, creating local conditions that shield galaxies from quenching mechanisms. If the conformity signal is indeed linked to LSS, we expect that removing galaxies embedded in filaments will lead to a decrease in this signal.To test this hyphothesis, we will identify filamentary structures in the outskirts of massive systems using the publicly available data from DisPerSE (for IllustrisTNG300), and an existing filament catalog from MDPL2-SAG. Additionally, we will examine the dependence of former satellites on their proximity to filaments and nodes.The dynamical state of galaxy groups and clusters will also be analyzed to assess their influence on surrounding galaxies. To ensure comparability with observations, the surrounding regions will be defined in terms of R200. This phase of the project will focus on z=0 and the nearby universe (z¿0.3), aligning with previous results (Palma+2025) on the conformity signal.Upcoming surveys such as CHANCES and WEAVE will provide unprecedented data on the low-mass regime, extending up to 5 virial radii from cluster centers. These surveys will allow us to study the impact of massive structures on their lo-mass neighbors. To complement these data, I will use the Southern Photometric Local Universe Survey (S-PLUSS; Mendes de Oliveira et al. 2019) to analyze the role of massive structures in shaping low-mass galaxy properties through photometric measurements. The survey's multi-filter photometry, including five broad and seven narrow bands, will facilitate the analysis of the conformity signal at low redshifts. Additionally, I aim to complete the analysis of galaxy clusters from the LoCuSS survey using observational data to examine the conformity signal in the outskirts of these clusters, providing insights of how environmental effects influence low-mass galaxies beyond the cluster cores, complementing insights gained from simulations.These results will refine our understanding of conformity by allowing direct comparisons with theoretical predictions. Furthermore, they can be contrasted with future findings from CHANCES and WEAVE, providing a more comprehensive picture of how massive structures influence their surroundings. As part of future work, I will also explore other semi-analytical models to assess the robustness of the conformity signal across different theoretical frameworks. Furthermore, the study will extend to high-redshift objects, such as protoclusters, to investigate whether the observed trends persist at earlier cosmic epochs. (AU)