Using the ARTEMIS set of 45 high-resolution cosmological simulations, we investigate a range merger-induced dynamical transformations Milky Way-like galaxies. We first identify populations accreted stars on highly radial orbits, similar to 'Gaia Sausage' in Way. show that $\approx1/3$ galaxies contain feature, and confirm they usually comprise stellar debris from most massive satellite. Selecting 15 with discs at present-day, study their changes around times GS-like mergers. Dark matter...

ABSTRACT Using data from the Gaia satellite’s Radial Velocity Spectrometer Data Release 3 (RVS, DR3), we find a new and robust feature in phase-space distribution of halo stars. It is prominent ridge at constant energy with angular momentum Lz > 0. We run test particle simulations stellar halo-like particles realistic Milky Way potential rotating bar. observe similar structures generated trapping resonances bar, particularly corotation resonance. Many orbits trapped are like, large...

ABSTRACT Relying on the dramatic increase in number of stars with full 6D phase-space information provided by Gaia Data Release 3, we resolve distribution stellar halo around Sun to uncover signatures incomplete phase-mixing. We show that, for likely belonging last massive merger, (vr, r) contains a series long and thin chevron-like overdensities. These substructures have been predicted emerge following dissolution satellite, when its tidal debris is given time wind up, out, fold. Such...

Overdensities in the radial phase space $(r,v_r)$ of Milky Way's halo have previously been associated with phase-mixed debris a highly merger event, such as Gaia Sausage-Enceladus. We present and test an alternative theory which overdense 'chevrons' are instead composed stars trapped resonances Galactic bar. develop analytic model resonant orbits isochrone potential, complement this particle simulation stellar realistic barred Way potential. These models used to predict appearance action...

ABSTRACT We investigate the effects of a massive ($\gtrsim 4\times 10^{10}\, \mathrm{M}_\odot$) Sagittarius dwarf spheroidal galaxy (Sgr) on stellar streams using test particle simulations in realistic Milky Way potential. find that Sgr can easily disrupt formed more than ∼3 Gyr ago, while stars stripped recently are generally unaffected. In certain realizations, is able to produce asymmetry between leading and trailing tails Pal 5, qualitatively similar observations. Using data from Gaia...

Radial migration is an important dynamical effect that has reshaped the Galactic disc, but its origin yet to be elucidated. In this work, we present evidence resonant dragging by corotation of a decelerating bar could main driver radial in Milky Way disc. Using test particle simulation, demonstrate scenario explains two distinct age-metallicity sequences observed solar vicinity: plateauing upper sequence interpreted as stars dragged outwards expanding and steeper lower formed locally around...

Abstract Radial migration is an important dynamical effect that has reshaped the Galactic disk, but its origin yet to be elucidated. In this work, we present evidence resonant dragging by corotation of a decelerating bar could main driver radial in Milky Way disk. Using test particle simulation, demonstrate scenario explains two distinct age–metallicity sequences observed solar vicinity: plateauing upper sequence interpreted as stars dragged outward expanding and steeper lower formed locally...

ABSTRACT We investigate the formation (spin-up) of galactic discs in artemis simulations Milky Way (MW)-mass galaxies. In almost all galaxies, spin up at higher [Fe/H] than MW. Those galaxies that contain an analogue Gaia Sausage-Enceladus (GSE) a lower average metallicity those without. identify six with spin-up similar to MW, which formed their ∼8–11 Gyr ago. Five these experience merger GSE. The times correlate halo masses early times: have larger virial lookback time tL = 12 Gyr....

ABSTRACT In this work, we look for evidence of a non-unity mass ratio binary dwarf galaxy merger in the Sagittarius stream. Simulations such show that, upon merging with host, particles from less massive will often mostly be found extended stream and so central remnant. Motivated by these simulations, use Apache Point Observatory Galactic Evolution Experiment Data Release 17 chemical data approximately 1100 stars both remnant to contamination second galaxy. We separate into its compare...

In a galaxy merger, the stars tidally stripped from satellite and accreted onto host undergo phase mixing form finely-grained structures in space. However, these fragile may be destroyed subsequent evolution, particular, by rotating bar that appears well after merger is completed. this work, we investigate survivability of phase-space presence bar. We find with amplitude pattern speed similar to those Milky Way would blur destroy substantial amount substructure consists particles pericentre...

ABSTRACT Overdensities in the radial phase space $(r,v_{\rm r})$ of Milky Way’s halo have previously been associated with phase-mixed debris a highly merger event such as Gaia Sausage–Enceladus. We present and test an alternative theory which overdense ‘chevrons’ are instead composed stars trapped resonances Galactic bar. develop analytic model resonant orbits isochrone potential, complement this particle simulation stellar realistic barred Way potential. These models used to predict...

Abstract We search for globular clusters (GCs) trapped in resonances with the bar of Milky Way (MW). By integrating their orbits a potential decelerating bar, we select 10 whose are significantly changed by its presence. Most these corotation resonance, including M22 and 47 Tuc. The is capable transporting GCs to current positions from much lower energies, angular momenta, radii. Our results indicate that likely have reshaped MW’s GC system via resonances. also discuss implications origins...

ABSTRACT Recent work uncovered features in the phase space of Milky Way’s stellar halo which may be attributed to last major merger. When material from a satellite is accreted onto its host, it mixes and appears finely substructured space. For high-eccentricity merger, this substructure most clearly manifests as numerous wrapping chevrons (vr, r) space, corresponding stripes (E, θr) We introduce idea using an alternative subhalo detector cold streams. simulate N-body merger akin GSE assess...

Using data from the Gaia satellite's Radial Velocity Spectrometer Data Release 3 (RVS, DR3), we find a new and robust feature in phase space distribution of halo stars. It is prominent ridge at constant energy with angular momentum $L_z>0$. We run test particle simulations stellar halo-like particles realistic Milky Way potential rotating bar. observe similar structures generated trapping resonances bar, particularly corotation resonance. Many orbits trapped are halo-like, large vertical...

Motivated by the LMC's impact on integral of motion space stellar halo, we run an $N$-body merger simulation to produce a population halo-like stars. We subsequently move test particle simulation, in which LMC perturbs this debris. When axisymmetric potential is assumed for final snapshot remnant, series vertical striations $(L_z, E)$ form as approaches its pericentre. These result from formation overdensities angular momentum owing relationship between precession rate near radial orbits and...

We investigate the formation (spin-up) of galactic discs in ARTEMIS simulations Milky Way-mass galaxies. In almost all galaxies spin up at higher [Fe/H] than Way (MW). Those that contain an analogue Gaia Sausage-Enceladus (GSE) a lower average metallicity those without. identify six with spin-up similar to MW, which form their $\sim 8-11$ Gyr ago. Five these experience merger GSE. The times correlate halo masses early times: have larger virial lookback time $t_L=12$ Gyr. fraction stars...

We report a correlation between the presence of Gaia-Sausage-Enceladus (GSE) analogue and dark matter halo spin in ARTEMIS simulations Milky Way-like galaxies. The haloes which contain large population accreted stars on highly radial orbits (like GSE) have lower average than their counterparts with more isotropic stellar velocity distributions. median modified parameters $\lambda^\prime$ differ by factor $\sim1.7$ at present-day, similar value when far from virial equilibrium are removed....

We search for globular clusters (GCs) trapped in resonances with the bar of Milky Way. By integrating their orbits a potential decelerating bar, we select 10 whose are significantly changed by its presence. Most these corotation resonance (CR), including M22 and 47 Tuc. The is capable transporting GCs to current positions from much lower energies, angular momenta, radii. Our results indicate that likely have reshaped Way's cluster system via resonances. also discuss implications origins...

In a galaxy merger, the stars tidally stripped from satellite and accreted onto host undergo phase mixing form finely-grained structures in space. However, these fragile may be destroyed subsequent evolution, particular, by rotating bar that appears well after merger is completed. this work, we investigate survivability of phase-space presence bar. We find with amplitude pattern speed similar to those Milky Way would blur destroy substantial amount substructure consists particles pericentre...

Relying on the dramatic increase in number of stars with full 6D phase-space information provided by Gaia Data Release 3, we discover unambiguous signatures phase-mixing stellar halo around Sun. We show that for likely belonging to last massive merger, (v_r,r) distribution contains a series long and thin chevron-like overdensities. These sub-structures are predicted emerge following dissolution satellite, when its tidal debris is given time wind up, out fold. Additionally, observed energy...

Motivated by the LMC's impact on integral of motion space stellar halo, we run an $N$-body merger simulation to produce a population halo-like stars. We subsequently move test particle simulation, in which LMC perturbs this debris. When axisymmetric potential is assumed for final snapshot remnant, series vertical striations $(L_z, E)$ form as approaches its pericentre. These result from formation overdensities angular momentum owing relationship between precession rate near radial orbits and...

In this work, we look for evidence of a non-unity mass ratio binary dwarf galaxy merger in the Sagittarius stream. Simulations such show that, upon merging with host, particles from less-massive will often mostly be found extended stream and less-so central remnant. Motivated by these simulations, use APOGEE DR17 chemical data approximately 1100 stars both remnant to contamination second galaxy. This search is initially justified idea that disrupted galaxies provide possible explanation...

We investigate the effects of a massive ($\gtrsim4\times10^{10}M_\odot$) Sagittarius dwarf spheroidal galaxy (Sgr) on stellar streams using test particle simulations in realistic Milky Way potential. find that Sgr can easily disrupt formed more than $\sim3$ Gyr ago, while stars stripped recently are generally unaffected. In certain realizations, is able to produce asymmetry between leading and trailing tails Pal 5, qualitatively similar observations. Using data from Gaia space telescope...

We report a correlation between the presence of Gaia-Sausage-Enceladus (GSE) analogue and dark matter halo spin in ARTEMIS simulations Milky Way-like galaxies. The haloes which contain large population accreted stars on highly radial orbits (like GSE) have lower average than their counterparts with more isotropic stellar velocity distributions. median modified parameters $λ^\prime$ differ by factor $\sim1.7$ at present-day, similar value when far from virial equilibrium are removed. also...