University of Surrey

Test tubes in the lab Research in the ATI Dance Research

On the origin of the asymmetric dwarf galaxy distribution around andromeda

Wan, Zhen, Oliver, William H, Lewis, Geraint F, Read, Justin and Collins, Michelle (2019) On the origin of the asymmetric dwarf galaxy distribution around andromeda Monthly Notices of the Royal Astronomical Society, 492 (1). pp. 456-467.

stz3477.pdf - Version of Record

Download (4MB) | Preview


The dwarf galaxy distribution surrounding M31 is significantly anisotropic in nature. Of the 30 dwarf galaxies in this distribution, 15 form a disc-like structure and 23 are contained within the hemisphere facing the Milky Way. Using a realistic local potential, we analyse the conditions required to produce and maintain these asymmetries. We find that some dwarf galaxies are required to have highly eccentric orbits in order to preserve the presence of the hemispherical asymmetry with an appropriately large radial dispersion. Under the assumption that the dwarf galaxies originate from a single association or accretion event, we find that the initial size and specific energy of that association must both be relatively large in order to produce the observed hemispherical asymmetry. However if the association was large in physical size, the very high-energy required would enable several dwarf galaxies to escape from the M31 and be captured by the Milky Way. Furthermore, we find that associations that result in this structure have total specific energies concentrated around E = V_esc2 - V_init2 ̃ 200^2 - 300^2 {km^2 s^{-2}}, implying that the initial velocity and initial position needed to produce the structure are strongly correlated. The overlap of initial conditions required to produce the radial dispersion, angular dispersion, and the planar structure is small and suggests that either they did not originate from a single accretion event, or that these asymmetric structures are short-lived.

Item Type: Article
Divisions : Faculty of Engineering and Physical Sciences > Physics
Authors :
Wan, Zhen
Oliver, William H
Lewis, Geraint F
Date : 12 December 2019
Funders : Institute of Advanced Studies
DOI : 10.1093/mnras/stz3477
Copyright Disclaimer : C 2019 The Author(s)
Uncontrolled Keywords : galaxies: evolution – galaxies: kinematics and dynamics.
Depositing User : James Marshall
Date Deposited : 29 Jan 2020 10:46
Last Modified : 29 Jan 2020 10:46

Actions (login required)

View Item View Item


Downloads per month over past year

Information about this web site

© The University of Surrey, Guildford, Surrey, GU2 7XH, United Kingdom.
+44 (0)1483 300800