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The Sausage Globular Clusters

  • Authors: G. C. Myeong, N. W. Evans, V. Belokurov, J. L. Sanders, and S. E. Koposov

2018 The Astrophysical Journal Letters 863 L28.

  • Provider: AAS Journals

Caption: Figure 3.

Upper panel: apocenters and pericenters of the GCs, color coded according to OH (red circles), YH (blue triangles), BD (yellow triangles), Sgr GCs (green diamonds), and unknown (gray cross). Sgr is also marked (black filled square). Lines of constant eccentricity from 0 to 0.9 in steps of 0.1 are shown in green. Note the Sausage GCs (black open circles as probables and open squares as possibles) all have eccentricity ≳0.80. Lower panels: Gaia selection effects. The gray pixels show the distribution of samples in action space of GCs at the observed locations of GCs, but with velocities randomly drawn from Gaussians with isotropic velocity dispersion σ = 130 km s−1 (left) and from the radially anisotropic dispersion found by Smith et al. (2009) for local halo stars (right). Only samples with −1.7 < E/105 (km2 s−2) < −1.2 and ﹩| {J}_{\phi }| \lt 700﹩ km s−1 kpc are shown. The actual locations of the Sausage GCs (red) and other GCs (pale blue) with ﹩-1.7\lt E/{10}^{5}(﹩km2 s−2) < −1.2 and ﹩| {J}_{\phi }| \lt 700﹩ km s−1 kpc are superposed. In the left panel, although there is a weak bias to low Jz, it is clear that Gaia could have detected objects at high Jz in this energy range if they existed. In the right panel, the relative lack of high Jz GCs is expected in such a radially anisotropic DF, but the GCs at large JR (the tips of the Sausage) are not.

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