A kinematic study of the Andromeda dwarf spheroidal system

Collins, Michelle L. M. and Chapman, Scott C. and Rich, R. Michael and Ibata, Rodrigo A. and Martin, Nicolas F. and Irwin, Michael J. and Bate, Nicholas F. and Lewis, Geraint F. and Peñarrubia, Jorge and Arimoto, Nobuo and Casey, Caitlin M. and Ferguson, Annette M. N. and Koch, Andreas and McConnachie, Alan W. and Tanvir, Nial (2013) A kinematic study of the Andromeda dwarf spheroidal system. The Astrophysical Journal, 768 (2). ISSN 0004-637X

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We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I LRIS and Keck II DEIMOS spectrographs. Based on their g-i colors (taken with the CFHT MegaCam imager), physical positions on the sky, and radial velocities, we assign probabilities of dSph membership to each observed star. Using this information, the velocity dispersions, central masses and central densities of the dark matter halos are calculated for these objects, and compared with the properties of the Milky Way dSph population. We also measure the average metallicity ([Fe/H]) from the co-added spectra of member stars for each M31 dSph and find that they are consistent with the trend of decreasing [Fe/H] with luminosity observed in the Milky Way population. We find that three of our studied M31 dSphs appear as significant outliers in terms of their central velocity dispersion, And XIX, XXI and XXV, all of which have large half-light radii (>700 pc) and low velocity dispersions (sigma_v

Item Type:
Journal Article
Journal or Publication Title:
The Astrophysical Journal
Additional Information:
41 pages, 23 figures. Accepted for publication in ApJ
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01 Dec 2016 11:20
Last Modified:
24 Jun 2020 04:09