The influence of Sagittarius and the Large Magellanic Cloud on the stellar disc of the Milky Way Galaxy

By C. Laporte, K. Johnston, F. G'omez, N. Garavito-Camargo, G. Besla. 2017

139 citations recorded by the source corpus.

We present N-body simulations of a Sagittarius-like dwarf spheroidal galaxy (Sgr) that follow its orbit about the Milky Way (MW) since its first crossing of the Galaxy's virial radius to the present day. As Sgr orbits around the MW, it excites vertical oscillations, corrugating and flaring the Galactic stellar disc. These responses can be understood by a two-phase picture in which the interaction is first dominated by torques from the wake excited by Sgr in the MW dark halo before transitioning to tides from Sgr's direct impact on the disc at late times. We show for the first time that a massive Sgr model simultaneously reproduces the locations and motions of arc-like over densities, such as the Monoceros Ring and the Triangulum Andromeda stellar clouds, that have been observed at the extremities of the disc, while also satisfying the solar neighbourhood constraints on the vertical structure and streaming motions of the disc. In additional simulations, we include the Large Magellanic Cloud (LMC) self consistently with Sgr. The LMC introduces coupling through constructive and destructive interference, but no new corrugations. In our models, the excitation of the current structure of the outer disk can be traced to interactions as far back as 6-7 Gyr ago (corresponding to $z\leq1$). Given the apparently quiescent accretion history of the MW over this timescale, this places Sgr as the main culprit behind the vertical oscillations of the disc and the last major accretion event for the Galaxy with the capacity to modulate its chemodynamical structure.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Yule-Simpson’s paradox in Galactic Archaeology (2019, background): “Disk flaring can be related to the dynamical effect of merging satellites, e.g., the Sagittarius dwarf (Laporte et al. 2018; Thomas et al. 2019).”
Evidence from the H3 Survey That the Stellar Halo Is Entirely Comprised of Substructure (2020, background): “…the other extreme of the plot, Sagittarius is the most α poor and metal rich of all the structures in the halo, likely because it was accreted very recently (z<1, e.g., Laporte et al. 2018; Kruijssen et al. 2020; Ruiz-Lara et al. 2020), after undergoing significant enrichment by Type Ia supernovae.”
Hunting for the Dark Matter Wake Induced by the Large Magellanic Cloud (2019, methodology): “We use the simulations presented in Laporte et al. (2018b), a suite of two N-body simulations of the interaction between the MW, LMC and Sgr and four additional simulations of the MW-Sgr interaction alone (no LMC).”
A-type stars in the Canada–France Imaging Survey – II. Tracing the height of the disc at large distances with Blue Stragglers (2018, background): “The projected Z − R distribution of a Galactic disc perturbed by a Sgr-like dwarf is shown in grey from Laporte et al. (2018a).”
Footprints of the Sagittarius dwarf galaxy in the Gaia data set (2018, methodology): “…et al. 2011; Gómez et al. 2013; Laporte et al. 2018a) and quantitative successes have only recently been achieved in the latest experiments of (Laporte et al. 2018b) which considered more realistic intial conditions in order to explain the origin of outer disc overdensities, thin stellar…”