Goater, Alex;
Read, Justin;
Noel, Noelia ED;
Orkney, Matthew DA;
Kim, Stacy Y;
Rey, Martin P;
Andersson, Eric P;
... Jeneway, Kiah; + view all
(2024)
EDGE: The direct link between mass growth history and the extended stellar haloes of the faintest dwarf galaxies.
Monthly Notices of the Royal Astronomical Society
, 527
(2)
pp. 2403-2412.
10.1093/mnras/stad3354.
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Abstract
Ultra-faint dwarf galaxies (UFDs) are commonly found in close proximity to the Milky Way and other massive spiral galaxies. As such, their projected stellar ellipticity and extended light distributions are often thought to owe to tidal forces. In this paper, we study the projected stellar ellipticities and faint stellar outskirts of tidally isolated ultra-faints drawn from the ‘Engineering Dwarfs at Galaxy Formation’s Edge’ (EDGE) cosmological simulation suite. Despite their tidal isolation, our simulated dwarfs exhibit a wide range of projected ellipticities (0.03 < ε < 0.85), with many possessing anisotropic extended stellar haloes that mimic tidal tails, but owe instead to late-time accretion of lower mass companions. Furthermore, we find a strong causal relationship between ellipticity and formation time of a UFD, which is robust to a wide variation in the feedback model. We show that the distribution of projected ellipticities in our suite of simulated EDGE dwarfs matches well with a sample of 19 Local Group dwarf galaxies and a sample of 11 isolated dwarf galaxies. Given ellipticity in EDGE arises from an ex-situ accretion origin, the agreement in shape indicates the ellipticities of some observed dwarfs may also originate from a non-tidal scenario. The orbital parameters of these observed dwarfs further support that they are not currently tidally disrupting. If the baryonic content in these galaxies is still tidally intact, then the same may be true for their dark matter content, making these galaxies in our Local Group pristine laboratories for testing dark matter and galaxy formation models.
| Type: | Article |
|---|---|
| Title: | EDGE: The direct link between mass growth history and the extended stellar haloes of the faintest dwarf galaxies |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stad3354 |
| Publisher version: | http://dx.doi.org/10.1093/mnras/stad3354 |
| Language: | English |
| Additional information: | Copyright © 2023 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | Galaxies: dwarf, galaxies: formation, galaxies: stellar content, galaxies: structure |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10187505 |
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