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Title: ARE SOME MILKY WAY GLOBULAR CLUSTERS HOSTED BY UNDISCOVERED GALAXIES?

Abstract

The confirmation of a globular cluster (GC) in the recently discovered ultrafaint galaxy Eridanus II (Eri II) motivated us to examine the question posed in the title. After estimating the halo mass of Eri II using a published stellar mass—halo mass relation, the one GC in this galaxy supports extending the relationship between the number of GCs hosted by a galaxy and the galaxy’s total mass about two orders of magnitude in stellar mass below the previous limit. For this empirically determined specific frequency of between 0.06 and 0.39 GCs per 10{sup 9} M {sub ⊙} of total mass, the surviving Milky Way (MW) subhalos with masses smaller than 10{sup 10} M {sub ⊙} could host as many as 5–31 GCs, broadly consistent with the actual population of outer halo MW GCs, although matching the radial distribution in detail remains a challenge. Using a subhalo mass function from published high-resolution numerical simulations and a Poissonian model for populating those halos with the aforementioned empirically constrained frequency, we find that about 90% of these GCs lie in lower-mass subhalos than that of Eri II. From what we know about the stellar mass–halo mass function, the subhalo mass function, and the mass-normalizedmore » GC specific frequency, we conclude that some of the MW’s outer halo GCs are likely to be hosted by undetected subhalos with extremely modest stellar populations.« less

Authors:
 [1]; ;  [2]
  1. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  2. Physics Department, Texas Tech University, Box 41051, Lubbock, TX 79409 (United States)
Publication Date:
OSTI Identifier:
22654272
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 826; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPUTERIZED SIMULATION; GALAXIES; GALAXY CLUSTERS; MASS; MILKY WAY; NONLUMINOUS MATTER; RESOLUTION; SPATIAL DISTRIBUTION

Citation Formats

Zaritsky, Dennis, Crnojević, Denija, and Sand, David J., E-mail: dennis.zaritsky@gmail.com. ARE SOME MILKY WAY GLOBULAR CLUSTERS HOSTED BY UNDISCOVERED GALAXIES?. United States: N. p., 2016. Web. doi:10.3847/2041-8205/826/1/L9.
Zaritsky, Dennis, Crnojević, Denija, & Sand, David J., E-mail: dennis.zaritsky@gmail.com. ARE SOME MILKY WAY GLOBULAR CLUSTERS HOSTED BY UNDISCOVERED GALAXIES?. United States. doi:10.3847/2041-8205/826/1/L9.
Zaritsky, Dennis, Crnojević, Denija, and Sand, David J., E-mail: dennis.zaritsky@gmail.com. 2016. "ARE SOME MILKY WAY GLOBULAR CLUSTERS HOSTED BY UNDISCOVERED GALAXIES?". United States. doi:10.3847/2041-8205/826/1/L9.
@article{osti_22654272,
title = {ARE SOME MILKY WAY GLOBULAR CLUSTERS HOSTED BY UNDISCOVERED GALAXIES?},
author = {Zaritsky, Dennis and Crnojević, Denija and Sand, David J., E-mail: dennis.zaritsky@gmail.com},
abstractNote = {The confirmation of a globular cluster (GC) in the recently discovered ultrafaint galaxy Eridanus II (Eri II) motivated us to examine the question posed in the title. After estimating the halo mass of Eri II using a published stellar mass—halo mass relation, the one GC in this galaxy supports extending the relationship between the number of GCs hosted by a galaxy and the galaxy’s total mass about two orders of magnitude in stellar mass below the previous limit. For this empirically determined specific frequency of between 0.06 and 0.39 GCs per 10{sup 9} M {sub ⊙} of total mass, the surviving Milky Way (MW) subhalos with masses smaller than 10{sup 10} M {sub ⊙} could host as many as 5–31 GCs, broadly consistent with the actual population of outer halo MW GCs, although matching the radial distribution in detail remains a challenge. Using a subhalo mass function from published high-resolution numerical simulations and a Poissonian model for populating those halos with the aforementioned empirically constrained frequency, we find that about 90% of these GCs lie in lower-mass subhalos than that of Eri II. From what we know about the stellar mass–halo mass function, the subhalo mass function, and the mass-normalized GC specific frequency, we conclude that some of the MW’s outer halo GCs are likely to be hosted by undetected subhalos with extremely modest stellar populations.},
doi = {10.3847/2041-8205/826/1/L9},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 826,
place = {United States},
year = 2016,
month = 7
}
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