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Kinematics of the Tucana Dwarf Galaxy: an unusually dense dwarf in the Local Group

Gregory, Alexandra L, Collins, Michelle L M, Read, Justin, Irwin, Michael J, Ibata, Rodrigo A, Martin, Nicolas F, McConnachie, Alan W and Weisz, Daniel R (2019) Kinematics of the Tucana Dwarf Galaxy: an unusually dense dwarf in the Local Group Monthly Notices of the Royal Astronomical Society, 485 (2). pp. 2010-2025.

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Abstract

We present new FLAMES+GIRAFFE spectroscopy of 36 member stars in the isolated Local Group dwarf spheroidal galaxy Tucana. We measure a systemic velocity for the system of vTuc=216.7+2.9−2.8vTuc=216.7−2.8+2.9 km s−1, and a velocity dispersion of σv,Tuc=14.4+2.8−2.3σv,Tuc=14.4−2.3+2.8 km s−1. We also detect a rotation gradient of dvrdχ=7.6+4.2−4.3dvrdχ=7.6−4.3+4.2 km s−1 kpc−1, which reduces the systemic velocity to vTuc=215.2+2.8−2.7vTuc=215.2−2.7+2.8 km s−1 and the velocity dispersion to σv,Tuc=13.3+2.7−2.3σv,Tuc=13.3−2.3+2.7 km s−1. We perform Jeans modelling of the density profile of Tucana, using the line-of-sight velocities of the member stars. We find that it favours a high central density consistent with ‘pristine’ subhaloes in Λ cold dark matter, and a massive dark matter halo (∼1010 M⊙) consistent with expectations from abundance matching. Tucana appears to be significantly more centrally dense than other isolated Local Group dwarfs, making it an ideal laboratory for testing dark matter models.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
NameEmailORCID
Gregory, Alexandra La.gregory@surrey.ac.uk
Collins, Michelle L Mm.collins@surrey.ac.uk
Read, Justinj.read@surrey.ac.uk
Irwin, Michael J
Ibata, Rodrigo A
Martin, Nicolas F
McConnachie, Alan W
Weisz, Daniel R
Date : 20 February 2019
DOI : 10.1093/mnras/stz518
Copyright Disclaimer : © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) Supple
Uncontrolled Keywords : Galaxies: dwarf. Galaxies: evolution. Galaxies: haloes. Galaxies: kinematics and dynamics. Local Group
Depositing User : Clive Harris
Date Deposited : 20 Mar 2019 10:45
Last Modified : 20 Mar 2019 10:45
URI: http://epubs.surrey.ac.uk/id/eprint/850811

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