The connection between the host halo and the satellite galaxies of the Milky Way
Abstract
Many properties of the Milky Way's (MW) dark matter halo, including its mass-assembly history, concentration, and subhalo population, remain poorly constrained. We explore the connection between these properties of the MW and its satellite galaxy population, especially the implication of the presence of the Magellanic Clouds for the properties of the MW halo. Using a suite of high-resolution N-body simulations of MW-mass halos with a fixed final M_(vir) ~ 10^(12.1),M_⊙, we find that the presence of Magellanic Cloud-like satellites strongly correlates with the assembly history, concentration, and subhalo population of the host halo, such that MW-mass systems with Magellanic Clouds have lower concentration, more rapid recent accretion, and more massive subhalos than typical halos of the same mass. Using a flexible semi-analytic galaxy formation model that is tuned to reproduce the stellar mass function of the classical dwarf galaxies of the MW with Markov-Chain Monte-Carlo, we show that adopting host halos with different mass-assembly histories and concentrations can lead to different best-fit models for galaxy-formation physics, especially for the strength of feedback. These biases arise because the presence of the Magellanic Clouds boosts the overall population of high-mass subhalos, thus requiring a different stellar-mass-to-halo-mass ratio to match the data. These biases also lead to significant differences in the mass–metallicity relation, the kinematics of low-mass satellites, the number counts of small satellites associated with the Magellanic Clouds, and the stellar mass of MW itself. Observations of these galaxy properties can thus provide useful constraints on the properties of the MW halo.
Additional Information
© 2016 American Astronomical Society. Received 2016 May 5; revised 2016 July 26; accepted 2016 July 27; published 2016 October 11. We thank Matthew Becker for providing the c125-2048 simulation, which was run using computing resources at SLAC. The resimulations were performed using computational resources at SLAC and at NERSC. We thank the SLAC computational team for their consistent support. We also acknowledge the Ahmanson Foundation for providing computational resources used in this work. Support for programs HST-AR-13270.003-A, HST-AR-13896.005-A, and HST-AR-13896.009-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Y.L. thanks Evan Kirby, Josh Simon, Robyn Sanderson, Shude Mao, and Simon White for useful discussions. S.T. was supported by the Alvin E. Nashman Fellowship in Theoretical Astrophysics. A.R.W. was supported by a Moore Prize Fellowship through the Moore Center for Theoretical Cosmology and Physics at Caltech and by a Carnegie Fellowship in Theoretical Astrophysics at Carnegie Observatories.Attached Files
Published - Lu_2016_ApJ_830_59.pdf
Submitted - 1605.02075v2.pdf
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Additional details
- Eprint ID
- 71011
- Resolver ID
- CaltechAUTHORS:20161012-082135875
- Ahmanson Foundation
- HST-AR-13270.003-A
- NASA
- HST-AR-13896.005-A
- NASA
- HST-AR-13896.009-A
- NASA
- NAS 5-26555
- NASA
- Caltech Moore Center for Theoretical Cosmology and Physics
- Carnegie Observatories
- Created
-
2016-10-12Created from EPrint's datestamp field
- Updated
-
2021-11-11Created from EPrint's last_modified field
- Caltech groups
- Moore Center for Theoretical Cosmology and Physics