Mapping Quasar Correlations Across Cosmic Web and Time

• Grant number: 25/17264-8
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Laerte Sodré Junior
• Grantee: Nathan Vieira de Oliveira
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Quasars are powerful tracers of the Cosmic Web, revealing an evolutionary trend in which their spatial distribution shifts from dense environments at cosmic noon to lower-density regions in the nearby Universe. This project aims to investigate underexplored correlations between quasar properties (e.g., luminosity, spectra, color) and their positions within Large-Scale Structure (LSS) components (filaments, voids, clusters, sheets) across cosmic time. Using data from observational surveys (e.g., DESI, eROSITA, SDSS, COSMOS), we plan to apply structure-finding algorithms (NEXUS+, DisPerSE, DBSCAN) to map the Cosmic Web and classify quasars. Key objectives include: quantifying the proportion of quasars in each LSS component; correlating filament/sheet topology with quasar properties; identifying environmental thresholds (e.g., cluster connectivity, graph-based morphology) that suppress black hole activity. Statistical analyses (e.g., Spearman, two-point correlation function, PCA) and machine learning (e.g., random forests, XGBoost) will test dependencies between quasar properties and environmental metrics.