2017/10/30 by Alexa Villaume, Jean Brodie, Charlie Conroy +2 · 28 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Galaxy #Globular cluster #Initial mass function #Metallicity #Population #Stellar mass #Stellar population #Stellar, planetary, and galactic studies #Variation (astronomy) #Velocity dispersion #astro-ph.GA
paper · pdf · doi:10.3847/2041-8213/aa970f
published in The Astrophysical Journal Letters 850(1), L14 (IOP Publishing) · Accepted to The Astrophysical Journal Letters
arxiv created 2017/10/30 · openalex created_date 2017/11/10 · openalex publication_date 2017/11/16 · arxiv updated 2017/11/29 · openalex updated_date 2026/08/06
Abstract Analyses of strong gravitational lenses, galaxy-scale kinematics, and absorption-line stellar population synthesis (SPS) have all concluded that the stellar initial mass function (IMF) varies within the massive early-type galaxy (ETG) population. However, the physical mechanism that drives variation in the IMF is an outstanding question. Here we use new SPS models to consider a diverse set of compact, low-velocity dispersion stellar systems: globular clusters (GCs), an ultra-compact dwarf (UCD), and the compact elliptical (cE) galaxy M32. We compare our results to massive ETGs and available dynamical measurements. We find that the GCs have stellar mass-to-light ratios ( M/L ) that are either consistent with a Kroupa IMF or are slightly bottom-light, while the UCD and cE have mildly elevated M/L . The separation in derived IMFs for systems with similar metallicities and abundance patterns indicates that our SPS models can distinguish abundance and IMF effects. Variation among the sample in this paper is only in normalized M/L compared to the among the ETG sample. This suggests that metallicity is not the sole driver of IMF variability and additional parameters need to be considered.