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Published January 2020 | Published + Submitted
Journal Article Open

A profile in FIRE: resolving the radial distributions of satellite galaxies in the Local Group with simulations

Abstract

While many tensions between Local Group (LG) satellite galaxies and Λ cold dark matter cosmology have been alleviated through recent cosmological simulations, the spatial distribution of satellites remains an important test of physical models and physical versus numerical disruption in simulations. Using the FIRE-2 cosmological zoom-in baryonic simulations, we examine the radial distributions of satellites with M∗>10⁵ M⊙ around eight isolated Milky Way (MW) mass host galaxies and four hosts in LG-like pairs. We demonstrate that these simulations resolve the survival and physical destruction of satellites with M∗≳10⁵ M⊙. The simulations broadly agree with LG observations, spanning the radial profiles around the MW and M31. This agreement does not depend strongly on satellite mass, even at distances ≲100 kpc. Host-to-host variation dominates the scatter in satellite counts within 300 kpc of the hosts, while time variation dominates scatter within 50 kpc. More massive host galaxies within our sample have fewer satellites at small distances, likely because of enhanced tidal destruction of satellites via the baryonic discs of host galaxies. Furthermore, we quantify and provide fits to the tidal depletion of subhaloes in baryonic relative to dark matter-only simulations as a function of distance. Our simulated profiles imply observational incompleteness in the LG even at M∗≳10⁵ M⊙: we predict 2–10 such satellites to be discovered around the MW and possibly 6–9 around M31. To provide cosmological context, we compare our results with the radial profiles of satellites around MW analogues in the SAGA survey, finding that our simulations are broadly consistent with most SAGA systems.

Additional Information

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2019 October 24. Received 2019 October 24; in original form 2019 April 25. Published: 31 October 2019. We thank Marla Geha, Risa Wechsler, and Ethan Nadler for their helpful comments. This research made use of ASTROPY,4 a community-developed core PYTHON package for Astronomy (Astropy Collaboration 2013, 2018), the IPYTHON package (Pérez & Granger 2007), NUMPY (Van Der Walt, Colbert & Varoquaux 2011), SCIPY (Jones et al. 2001), NUMBA (Lam, Pitrou & Seibert 2015), and MATPLOTLIB, a PYTHON library for publication quality graphics (Hunter 2007). JS, AW, and SB were supported by the National Aeronautics and Space Administration (NASA) through Astrophysics Theory Program (ATP) grant 80NSSC18K1097 and Hubble Space Telescope (HST) grants GO-14734 and AR-15057 from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS5-26555. We performed this work in part at the Aspen Center for Physics, supported by the National Science Foundation (NSF) grant PHY-1607611, and at the Kavli Institue for Theoretical Physics (KITP), supported by NSF grant PHY-1748958. Support for SGK and PFH was provided by an Alfred P. Sloan Research Fellowship, NSF grant #1715847, CAREER grant #1455342, NASA grant NNX15AT06G, and Jet Propulsion Laboratory (JPL) grants 1589742 ,17-ATP17-0214. Support for SL was provided by NASA through Hubble Fellowship grant #HST-JF2-51395.001-A awarded by STScI. KE was supported by an NSF graduate research fellowship. MBK acknowledges support from NSF grant AST-1517226, CAREER grant AST-1752913, and from NASA grants NNX17AG29G and HST-AR-13888, HST-AR-13896, HST-AR-14282, HST-AR-14554, HST-AR-15006, HST-GO-12914, and HST-GO-14191 from STScI. CAFG was supported by NSF through grants AST-1517491, AST-1715216, and CAREER award AST-1652522, by NASA through grant 17-ATP17-0067, and by a Cottrell Scholar Award from the Research Corporation for Science Advancement. JSB was supported by NSF AST-1518291, HST-AR-14282, and HST-AR-13888. We ran simulations using the Extreme Science and Engineering Discovery Environment (XSEDE) supported by NSF grant ACI-1548562, Blue Waters via allocation PRAC NSF.1713353 supported by the NSF, and NASA HEC Program through the NAS Division at Ames Research Center.

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Additional details

Created:
August 19, 2023
Modified:
October 18, 2023