Tracing the first stars and galaxies of the Milky Way

• Main Authors: Griffen, Brendan F. (Author), Dooley, Gregory Alan (Author), Ji, Alexander Pung (Author), O'Shea, Brian W (Author), Gómez, Facundo A (Author), Frebel, Anna L. (Author)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), MIT Kavli Institute for Astrophysics and Space Research (Contributor)
• Format: Article
• Language: English
• Published: Oxford University Press (OUP), 2019-06-04T19:58:32Z.
• Subjects: Article
• Online Access: Get fulltext

We use 30 high-resolution dark matter haloes of the Caterpillar simulation suite to probe the first stars and galaxies of MilkyWay-mass systems. We quantify the environment of the high-z progenitors of theMilkyWay and connect them to the properties of the host and satellites today. We identify the formation sites of the first generation of Population III (Pop III) stars (z ~ 25) and first galaxies (z ~ 22) with several different models based on a minimum halo mass. This includes a simple model for radiative feedback, the primary limitation of the model. Through this method we find approximately 23 000 ± 5000 Pop III potentially star-forming sites per MilkyWay-mass host, though this number is drastically reduced to ~550 star-forming sites if feedback is included. The majority of these haloes identified form in isolation (96 per cent at z = 15) and are not subject to external enrichment by neighbouring haloes (median separation ~1 kpc at z = 15), though half merge with a system larger than themselves within 1.5 Gyr. Using particle tagging, we additionally trace the Pop III remnant population to z = 0 and find an order of magnitude scatter in their number density at small (i.e. r < 5 kpc) and large (i.e. r > 50 kpc) galactocentric radii. We provide fitting functions for determining the number of progenitor minihalo and atomic cooling halo systems that present-day satellite galaxies might have accreted since their formation. We determine that observed dwarf galaxies with stellar masses below 10[superscript 4.6]M[subscript ⊙] are unlikely to have merged with any other star-forming systems. Keywords: Galaxy: halo; galaxies: evolution; galaxies: formation; dark ages; reionization; first stars; dark matter; cosmology: theory
National Science Foundation (U.S.) (Grant 1122374)
National Science Foundation (U.S.) (Grant PHY-0941373)
National Science Foundation (U.S.) (Grant PHY 08-22648)
National Science Foundation (U.S.) (Grant PHY-1430152)
United States. National Aeronautics and Space Administration (Grant NNX12AC98G)
United States. National Aeronautics and Space Administration (Grant NNX15AP39G)
United States. National Aeronautics and Space Administration (Grant HST-AR-13261.01-A)
United States. National Aeronautics and Space Administration (Grant HST-AR-14315.001-A)