A Two-Point Correlation Function For Galactic Halo Stars

Abstract

We describe a correlation function statistic that quantifies the amount of spatial and kinematic substructure in the stellar halo. We test this statistic using model stellar halo realizations constructed from the Aquarius suite of six high-resolution N-body simulations in combination with the Galform semi-analytic galaxy formation model. These simulations show considerable scatter in the properties of stellar haloes. We find that our statistic can distinguish between these plausible alternatives for the global structure of the Milky Way stellar halo. We compare with observational data and show that pencil beam surveys of ~100 tracer stars (such as the Spaghetti Survey) are not sufficient to constrain the degree of structure in the Milky Way halo with this statistic. Larger area surveys with >1000 tracer stars (such as BHB stars in the Sloan Digital Sky Survey) provide much tighter constraints on comparisons between models and data. In our simulations, we find examples of haloes with spatial and kinematic substructure consistent with the available Milky Way data.

10 pages, 6 figures, accepted by MNRAS; bug in correlation function code fixed. Key figures updated, analysis of distance dependence included. Conclusions unchanged. For a related article by another group see arXiv:1011.1925

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Cited by in corpus (25)

• Ages and kinematics of chemically selected, accreted Milky Way halo stars
• Formation of In Situ Stellar Haloes in Milky Way-Mass Galaxies
• Galactic Stellar Populations in the Era of SDSS and Other Large Surveys
• Characterising stellar halo populations I: An extended distribution function for halo K giants
• Identifying Contributions to the Stellar Halo from Accreted, Kicked-Out, and In Situ Populations
• Creating mock catalogues of stellar haloes from cosmological simulations
• The SEGUE K Giant Survey. III. Quantifying Galactic Halo Substructure
• Identifying Galactic Halo Substructure in 6D Phase-space Using $\sim$13,000 LAMOST K Giants
• Quantifying the Smoothness of the Stellar Halo: A Link to Accretion History
• What to expect from dynamical modelling of galactic haloes
• Comparing semi-analytic particle tagging and hydrodynamical simulations of the Milky Way's stellar halo
• Particle tagging and its implications for stellar population dynamics
• Kinematically Detected Halo Streams
• Spatial and Kinematic Clustering of Stars in the Galactic Disk
• Jeans that fit: weighing the mass of the Milky Way analogues in the $\Lambda \mathrm{CDM}$ universe
• Auriga Streams I: disrupting satellites surrounding Milky Way-mass haloes at multiple resolutions
• Milky Way simulations: the Galaxy, its stellar halo and its satellites - insights from a hybrid cosmological approach
• Characterizing the SHARDS of Disrupted Milky Way Satellites with LAMOST
• Mapping the Milky Way's stellar halo with 2D data
• Two-point correlation function studies for the Milky Way: discovery of spatial clustering from disk excitations and substructure
• Luminous Satellites versus Dark Subhaloes: Clustering in the Milky Way
• Architecture of the Andromeda: a quantitative analysis of clustering in the inner stellar halo
• Using two point correlation functions to understand the assembly histories of Milky Way-like galaxies
• The mass and redshift dependence of halo star clustering
• Kolmogorov complexity in the Milky Way and its reduction with warm dark matter