THE GLOBULAR CLUSTER SYSTEM OF THE MILKY WAY: ACCRETION IN A COSMOLOGICAL CONTEXT
Abstract
We examine the significance of a planar arrangement in the spatial distribution of the Milky Way (MW) globular clusters (GCs). We find that, when separated on the basis of horizontal branch morphology and metallicity, the outermost canonical young halo (YH) GC sample (at galactocentric radii in excess of 10 kpc) exhibits an anisotropic distribution that may be equated to a plane (24 {+-} 4) kpc thick (rms) and inclined at 8 Degree-Sign {+-} 5 Degree-Sign to the polar axis of the MW disk. To quantify the significance of this plane we determine the fraction of times that an isotropic distribution replicates the observed distribution in Monte Carlo trials. The plane is found to remain significant at the >95% level outside a galactocentric radius of 10 kpc, inside this radius the spatial distribution is apparently isotropic. In contrast, the spatial distribution of the old halo sample outside 10 kpc is well matched by an isotropic distribution. The plane described by the outer YH GCs is indistinguishable in orientation from that presented by the satellite galaxies of the MW. Simulations have shown that the planar arrangement of satellites can arise as filaments of the surrounding large-scale structure feed into the MW's potential.more »
- Authors:
-
- RSAA, Australian National University, Weston Creek, ACT 2611 (Australia)
- Publication Date:
- OSTI Identifier:
- 22004339
- Resource Type:
- Journal Article
- Journal Name:
- Astrophysical Journal
- Additional Journal Information:
- Journal Volume: 744; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; GALACTIC EVOLUTION; MILKY WAY; MONTE CARLO METHOD; MORPHOLOGY; SATELLITES; SIMULATION; SPATIAL DISTRIBUTION
Citation Formats
Keller, Stefan C, Mackey, Dougal, and Da Costa, Gary S. THE GLOBULAR CLUSTER SYSTEM OF THE MILKY WAY: ACCRETION IN A COSMOLOGICAL CONTEXT. United States: N. p., 2012.
Web. doi:10.1088/0004-637X/744/1/57.
Keller, Stefan C, Mackey, Dougal, & Da Costa, Gary S. THE GLOBULAR CLUSTER SYSTEM OF THE MILKY WAY: ACCRETION IN A COSMOLOGICAL CONTEXT. United States. https://doi.org/10.1088/0004-637X/744/1/57
Keller, Stefan C, Mackey, Dougal, and Da Costa, Gary S. 2012.
"THE GLOBULAR CLUSTER SYSTEM OF THE MILKY WAY: ACCRETION IN A COSMOLOGICAL CONTEXT". United States. https://doi.org/10.1088/0004-637X/744/1/57.
@article{osti_22004339,
title = {THE GLOBULAR CLUSTER SYSTEM OF THE MILKY WAY: ACCRETION IN A COSMOLOGICAL CONTEXT},
author = {Keller, Stefan C and Mackey, Dougal and Da Costa, Gary S},
abstractNote = {We examine the significance of a planar arrangement in the spatial distribution of the Milky Way (MW) globular clusters (GCs). We find that, when separated on the basis of horizontal branch morphology and metallicity, the outermost canonical young halo (YH) GC sample (at galactocentric radii in excess of 10 kpc) exhibits an anisotropic distribution that may be equated to a plane (24 {+-} 4) kpc thick (rms) and inclined at 8 Degree-Sign {+-} 5 Degree-Sign to the polar axis of the MW disk. To quantify the significance of this plane we determine the fraction of times that an isotropic distribution replicates the observed distribution in Monte Carlo trials. The plane is found to remain significant at the >95% level outside a galactocentric radius of 10 kpc, inside this radius the spatial distribution is apparently isotropic. In contrast, the spatial distribution of the old halo sample outside 10 kpc is well matched by an isotropic distribution. The plane described by the outer YH GCs is indistinguishable in orientation from that presented by the satellite galaxies of the MW. Simulations have shown that the planar arrangement of satellites can arise as filaments of the surrounding large-scale structure feed into the MW's potential. We therefore propose that our results are direct observational evidence for the accreted origin of the outer YH GC population. This conclusion confirms numerous lines of evidence that have similarly indicated an accreted origin for this set of clusters from the inferred cluster properties.},
doi = {10.1088/0004-637X/744/1/57},
url = {https://www.osti.gov/biblio/22004339},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 744,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2012},
month = {Sun Jan 01 00:00:00 EST 2012}
}