Type: Talk
Session: Galaxies Science from Dwarfs to Clusters
Author: Burcin Mutlu-Pakdil

Abstract: Local Group satellites have been the primary sample for understanding the astrophysics and cosmological implications of dwarf galaxies. However, there is a danger of ‘overtailoring’ the models to fit local observations. To fully test the ΛCDM model and its underlying astrophysics, studies of satellite systems beyond the Local Group are necessary to sample primary halos with a range of masses, morphologies, and environments. To address this fundamental need, we started PISCeS, a Magellan+Megacam survey to identify dwarfs and other substructures in resolved stellar light around Milky Way (MW)-mass galaxies outside the Local Group. We recently completed the survey around NGC253 (at 3.5 Mpc), the nearest MW-mass spiral galaxy in an isolated environment, providing us with a unique opportunity to extend the range of environments probed by the existing surveys. We take a deeper look at the faint satellite system of NGC253, and find no convincing evidence for the presence of a plane of satellites surrounding NGC253. We construct its satellite luminosity function, and compare it to those calculated for other Local Volume galaxies. Exploring trends in satellite counts and star-forming fractions among satellite systems, we find relationships with host stellar mass, environment, and morphology, pointing to a complex picture of satellite formation, and a successful model has to reproduce all of these trends. In this talk, I will present these exciting PISCeS results, discuss complementary ongoing efforts, and conclude with a preview of what is possible with LSST in the coming decade.