Characterizing the multicomponent density structure of galaxies

Abstract

Abridged) Quantifying the 3D spatial structure of galaxies forms a key element in furthering our understanding of the formation and evolution of galaxies and consequently the universe. What we observe, however, is a 2D projection (on the plane of the sky) of the intensity of light of galaxies. Inferring the intrinsic 3D distribution is critical for the understanding of galaxies, but technically difficult. Despite 80 years of research, we still do not have a consensus on a model that can describe the 2D projected light of galaxies over their entire spatial extent.In the first part of this work, I summarize existing models and then show how one can efficiently model the high resolution light profiles of galaxies to quantify both the 2D and the 3D distributions and also infer the existence of multiple components in a galaxy. Using data of 23 galaxies from the Virgo Cluster, I present models of their light profiles with mean residuals of ~ 3% (that is consistent with measurement errors) over a radial range spanning an order of up to 10^5 -- an unprecedented accuracy over such large spatial extent. Consequences of such models are discussed, especially an evidence for an universality in the functional form that describes both the baryonic and dark matter distributions. In the second part of this work, I demonstrate a novel way of obtaining projections of intrinsic quantities when the standard method does not yield analytical solutions, i.e. a procedure to perform otherwise difficult analytical integrations.