One acceleration measurement equals ~10^5 phase-space measurements for local dark matter density estimation, with acceleration outperforming Jeans modeling in both equilibrium and perturbed Milky Way simulations.
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The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
13 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
The assembly process of our Galaxy can be retrieved using the motions and chemistry of individual stars. Chemo-dynamical studies of the nearby halo have long hinted at the presence of multiple components such as streams, clumps, duality and correlations between the stars' chemical abundances and orbital parameters. More recently, the analysis of two large stellar surveys have revealed the presence of a well-populated chemical elemental abundance sequence, of two distinct sequences in the colour-magnitude diagram, and of a prominent slightly retrograde kinematic structure all in the nearby halo, which may trace an important accretion event experienced by the Galaxy. Here report an analysis of the kinematics, chemistry, age and spatial distribution of stars in a relatively large volume around the Sun that are mainly linked to two major Galactic components, the thick disk and the stellar halo. We demonstrate that the inner halo is dominated by debris from an object which at infall was slightly more massive than the Small Magellanic Cloud, and which we refer to as Gaia-Enceladus. The stars originating in Gaia-Enceladus cover nearly the full sky, their motions reveal the presence of streams and slightly retrograde and elongated trajectories. Hundreds of RR Lyrae stars and thirteen globular clusters following a consistent age-metallicity relation can be associated to Gaia-Enceladus on the basis of their orbits. With an estimated 4:1 mass-ratio, the merger with Gaia-Enceladus must have led to the dynamical heating of the precursor of the Galactic thick disk and therefore contributed to the formation of this component approximately 10 Gyr ago. These findings are in line with simulations of galaxy formation, which predict that the inner stellar halo should be dominated by debris from just a few massive progenitors.
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A neural network trained on simulations infers stripping times for Sagittarius stream stars from phase-space data, measuring a 0.3 dex/Gyr metallicity gradient and estimating ages for globular clusters such as Pal 12 and NGC 2419.
N-body simulations show high-z proto-star clusters with multiple populations can survive strong early tidal fields and evolve into systems with properties matching Galactic globular clusters after 12 Gyr.
AuriGLOBES is a new subgrid model implemented in Auriga simulations that incorporates compressive tides and compact-object mass loss to transform an initial Schechter mass function into observed globular cluster populations while reproducing the GC system mass-halo mass relation.
Galaxy size at fixed stellar mass encodes the link between long-term gas inflow histories, current inner gas reservoirs, and metallicity via differences in assembly timing.
Koposov 2 is shown to be an old (13.7 Gyr) star cluster with half-light radius 2.7 pc, absolute magnitude -0.95, and stellar mass 372 solar masses, supporting a star cluster classification over a dwarf galaxy.
Hot Jupiter occurrence in the Galactic halo is low at ~0.13% with no significant difference between in-situ and accreted populations, well below disk rates.
N-body simulations of the Milky Way-GSE merger indicate that halo and merger-formed globular clusters largely retain orbital energy, allowing most GSE-linked GCs to trace accretion events in the E-Lz plane.
A lithium chemical evolution model for the GSE galaxy matches survey data showing Spite-like and eRGB plateaus at low metallicity with a hint of reduced nova contributions.
ARTEMIS and EAGLE simulations classify L* galaxies by central BH-to-stellar-mass ratio and trace how merger history drives divergence in BH growth, star formation, and morphology, offering an explanation for the observed scatter and for MW/M31 differences.
Phase-space density is recovered from Gaia data for M4 and disrupted streams by correcting entropy injection and minimizing stream entropy, enabling original mass inference via Liouville's theorem.
Resolved stellar property gradients in Milky Way analog progenitors show inside-out assembly with minor, temporary disruption from major mergers.
High-precision analysis of TYC 6044-714-1 favors s+r nucleosynthesis over i-process models, which require implausible conditions and mismatch Ba isotopes.
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Applying Liouville's Theorem to Gaia Data
Phase-space density is recovered from Gaia data for M4 and disrupted streams by correcting entropy injection and minimizing stream entropy, enabling original mass inference via Liouville's theorem.