Project Details
Projekt
Unveiling the link between galaxies and large-scale structures in the Sloan Digital Sky Survey
Applicant
Professor Dr. Cristiano Porciani
Subject Area
Astrophysics and Astronomy
Term
from 2009 to 2012
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 127016664
Redshift surveys have revealed that galaxies trace a complex network of structures where prominent high-density features as clusters and filaments are interweaved with large nearly empty regions. Theoretical models and simulations show that a “cosmic web”, qualitatively similar to the observed one, is naturally produced by the gravitational instability of tiny density perturbations produced in the early universe. A quantitative observational study of the cosmic web has long been impossible because galaxy redshift surveys either covered too small a volume or had too a low sampling rate to allow an automatic and objective detection of large-scale structures. However, the revolutionary progress in mapping the low-redshift universe enabled by the latest generation of surveys has filled this gap. On the other hand, we are now in uncharted territory, because the tools necessary to identify the large-scale structures are lacking. Building on our past experience with numerical simulations and large observational samples, we thus propose to:1. develop a general and simple method to identify large-scale structures such as voids, walls, filaments and clumps in large galaxy catalogs with high sampling rate;2. apply the method to the Sloan Digital Sky Survey (SDSS) so that to identify galaxies in different large-scale environments;3. investigate if and how the fundamental properties of SDSS galaxies correlate with the large-scale environment and, in particular, collect evidence for cold-gas accretion onto galaxies along filaments;4. quantify the alignment between SDSS galaxies and their host large-scale structures.In return, this research programme will1. open a new chapter in the study of galaxy clustering so far dominated by measurements of 2-point and 3-point statistics;2. connect the small-scale physics of galaxies with the assembly of the large-scale structure, thus bridging galaxy formation and cosmology;3. clarify the origin of galactic spins and shapes and their relation to the underlying large-scale structure;4. understand the origin of intrinsic galaxy-galaxy and galaxy-shear alignments that plague cosmic-shear surveys.
DFG Programme
Priority Programmes
