Abstract / Description of output
M31 has a giant stream of stars extending far to the south and a great
deal of other tidal debris in its halo, much of which is thought to be
directly associated with the southern stream. We model this structure by
means of Bayesian sampling of parameter space, where each sample uses an
N-body simulation of a satellite disrupting in M31's potential. We
combine constraints on stellar surface densities from the Isaac Newton
Telescope survey of M31 with kinematic data and photometric distances.
This combination of data tightly constrains the model, indicating a
stellar mass at last pericentric passage of log10
(Ms/M⊙) = 9.5 ± 0.1, comparable to the
Large Magellanic Cloud. Any existing remnant of the satellite is
expected to lie in the Northeast (NE) Shelf region beside M31's disc, at
velocities more negative than M31's disc in this region. This rules out
the prominent satellites M32 or NGC 205 as the progenitor, but an
overdensity recently discovered in M31's NE disc sits at the edge of the
progenitor locations found in the model. M31's virial mass is
constrained in this model to be log10 M200 = 12.3
± 0.1, alleviating the previous tension between observational
virial mass estimates and expectations from the general galactic
population and the timing argument. The techniques used in this paper,
which should be more generally applicable, are a powerful method of
extracting physical inferences from observational data on tidal debris
structures.
Original language | English |
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Pages (from-to) | 2779-2802 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 434 |
Publication status | Published - 1 Oct 2013 |
Keywords / Materials (for Non-textual outputs)
- methods: statistical
- galaxies: haloes
- galaxies: individual: M31
- galaxies: interactions
- galaxies: kinematics and dynamics