Dark Galaxies and Integrated Knowledge: The View from 116 Megaparsecs Away

Michael Weisberg (University of Pennsylvania)

ABSTRACT: Astronomers believe that dark matter rings all luminous galaxies in gigantic halos. While this is widely accepted, these halos only account for a fraction of the total mass of dark matter believed to exist in the universe. Where is the rest? Is it possible to find it? And how can such a feat be possible? The search for dark matter provides an important case study of the use of models in science and of how knowledge can be integrated across multiple types of evidence. In this talk, I will describe a collaborative search for missing dark matter undertaken by philosophers and astrophysicists. My collaborators and I defend the view that a large fraction of dark matter resides in dark galaxies, dark matter halos that either never possessed or have totally lost their baryonic matter at some time in the past. Finding these dark galaxies, which are invisible to any known detector, requires integrating knowledge across many scientific disciplines and modalities. Only through the use of multiple highly idealized models can we even begin to understand observations made through our telescopes. I will explore the nature of this integration and what it can tell us about the epistemology of science more generally.