A Caltech Library Service

How low does it go? Too few Galactic satellites with standard reionization quenching

Graus, Andrew S. and Bullock, James S. and Kelley, Tyler and Boylan-Kolchin, Michael and Garrison-Kimmel, Shea and Qi, Yuewen (2019) How low does it go? Too few Galactic satellites with standard reionization quenching. Monthly Notices of the Royal Astronomical Society, 488 (4). pp. 4585-4595. ISSN 0035-8711.

[img] PDF - Published Version
See Usage Policy.

[img] PDF - Submitted Version
See Usage Policy.


Use this Persistent URL to link to this item:


A standard prediction of galaxy formation theory is that the ionizing background suppresses galaxy formation in haloes with peak circular velocities smaller than V_(peak) ≃ 20kms^(−1), rendering the majority of haloes below this scale completely dark. We use a suite of cosmological zoom simulations of Milky Way-like haloes that include central Milky Way disc galaxy potentials to investigate the relationship between subhaloes and ultrafaint galaxies. We find that there are far too few subhaloes within 50 kpc of the Milky Way that had V_(peak) ≳ 20kms^(−1) to account for the number of ultrafaint galaxies already known within that volume today. In order to match the observed count, we must populate subhaloes down to V_(peak) ≃ 6kms^(−1) with ultrafaint dwarfs. The required haloes have peak virial temperatures as low as 1500 K, well below the atomic hydrogen cooling limit of 10^4 K. Allowing for the possibility that the Large Magellanic Cloud contributes several of the satellites within 50 kpc could potentially raise this threshold to 10kms^(−1) (4000 K), still below the atomic cooling limit and far below the nominal reionization threshold.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Bullock, James S.0000-0003-4298-5082
Boylan-Kolchin, Michael0000-0002-9604-343X
Garrison-Kimmel, Shea0000-0002-4655-8128
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 ( Accepted 2019 July 17. Received 2019 July 16; in original form 2018 August 10. Published: 26 July 2019. The authors would like to thank Josh Simon for providing the dispersion velocities of dwarf satellites used in this work, and Alyson Brooks, Alex Drlica-Wagner, and Denis Erkal for useful discussions. We also thank the anonymous referee for their helpful comments on the manuscript. ASG, TK, CQ, and JSB were supported by NSF AST-1518291, HST-AR-14282, and HST-AR-13888. MBK acknowledges support from NSF grant AST-1517226 and 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 the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. Support for SGK was provided by NASA through the Einstein Postdoctoral Fellowship grant number PF5-160136 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. This work used computational resources of the Texas Advanced Computing Center (TACC;, the NASA Advanced Supercomputing (NAS) Division and the NASA Center for Climate Simulation (NCCS), and the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number OCI-1053575.
Funding AgencyGrant Number
NASA Einstein FellowshipPF5-160136
Subject Keywords:galaxies: dwarf – galaxies: formation – (galaxies:) Local Group – cosmology: theory – (cosmology:) dark ages, reionization, first stars
Issue or Number:4
Record Number:CaltechAUTHORS:20190926-132243371
Persistent URL:
Official Citation:Andrew S Graus, James S Bullock, Tyler Kelley, Michael Boylan-Kolchin, Shea Garrison-Kimmel, Yuewen Qi, How low does it go? Too few Galactic satellites with standard reionization quenching, Monthly Notices of the Royal Astronomical Society, Volume 488, Issue 4, October 2019, Pages 4585–4595,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98877
Deposited By: Tony Diaz
Deposited On:26 Sep 2019 20:46
Last Modified:15 Nov 2019 03:58

Repository Staff Only: item control page