We introduce a suite of 30 cosmological magneto-hydrodynamical zoom simulations the formation galaxies in isolated Milky Way mass dark haloes. These were carried out with moving mesh code arepo, together comprehensive model for galaxy physics, including active galactic nuclei (AGN) feedback and magnetic fields, which produces realistic populations large simulations. demonstrate that our reproduce wide range present-day observables, particular, two-component disc-dominated appropriate stellar...

We determine the Milky Way (MW) mass profile inferred from fitting physically motivated models to Gaia DR2 Galactic rotation curve and other data. Using various hydrodynamical simulations of MW-mass haloes, we show that presence baryons induces a contraction dark matter (DM) distribution in inner regions, r<20 kpc. provide an analytic expression relates baryonic change DM halo profile. For our galaxy, increases enclosed by factors roughly 1.3, 2 4 at radial distances 20, 8 1 kpc,...

We analyse an N-body simulation of the interaction Milky Way (MW) with a Sagittarius-like dSph (Sgr), looking for signatures which may be attributed to its orbital history in phase space volume around Sun light $Gaia$ DR2 discoveries. The repeated impacts Sgr excite coupled vertical and radial oscillations disc qualitatively, large degree quantitatively are able reproduce many features 6D samples, from median $V_{R},V_{\phi}, V_{z} $ velocity maps local $\delta\rho(v_{z},z)$ phase-space...

We present N-body simulations of a Sagittarius-like dwarf spheroidal galaxy (Sgr) that follow its orbit about the Milky Way (MW) since first crossing Galaxy's virial radius to day. As Sgr orbits around MW, it excites vertical oscillations, corrugating and flaring Galactic stellar disc. These responses can be understood by two-phase picture in which interaction is dominated torques from wake excited MW dark halo before transitioning tides Sgr's direct impact on disc at late times. show for...

Abstract This paper explores the effect of Large Magellanic Cloud (LMC) on mass estimates obtained from timing argument. We show that accounting for presence LMC systematically lowers Local Group (MLG) derived relative motion Milky Way–Andromeda pair. Motivated by this result, we apply a Bayesian technique devised Peñarrubia et al. to simultaneously fit (i) distances and velocities galaxies within 3 Mpc (ii) between Way Andromeda HST observations, with (MLMC) as free parameter. Our analysis...

We present predictions for the quenching of star formation in satellite galaxies Local Group from a suite 30 cosmological zoom simulations Milky Way-like host galaxies. The Auriga resolve satellites down to luminosity classical dwarf spheroidal Way. find strong mass-dependent and distance-dependent signals, where systems beyond 600 kpc are only strongly quenched below stellar mass 107 M⊙. Ram pressure stripping appears be dominant mechanism 50 per cent cease within 1 Gyr first infall....

Abstract With the release of Gaia DR2, it is now possible to measure proper motions (PMs) lowest-mass, ultrafaint satellite galaxies in Milky Way’s (MW) halo for first time. Many these faint satellites are posited have been accreted as Magellanic Clouds (MCs). Using their six-dimensional phase-space information, we calculate orbital histories 13 and five classical dwarf spheroidals a combined MW+LMC+SMC potential determine which dynamically associated with MCs. These 18 separated into four...

We examine the stellar haloes of Auriga simulations, a suite thirty cosmological magneto-hydrodynamical high-resolution simulations Milky Way-mass galaxies performed with moving-mesh code AREPO. study halo global properties and radial profiles out to $\sim 150$ kpc for each individual galaxy. The are diverse in their masses density profiles; mean metallicity gradients; ages; shapes, reflecting stochasticity inherent accretion merger histories. A comparison observations nearby late-type shows...

Recently, Widrow and collaborators announced the discovery of vertical density waves in Milky Way disk. Here we investigate a scenario where these were induced by Sagittarius dwarf galaxy as it plunged through Galaxy. Using numerical simulations, find that impact produces North-South asymmetries wave-like behavior qualitatively agrees with what is observed. The extent to which modes can radially penetrate into disc, well their amplitudes, depend on mass perturbing satellite. We show mean...

Motivated by recent studies suggesting that the Large Magellanic Cloud (LMC) could be significantly more massive than previously thought, we explore whether approximation of an inertial Galactocentric reference frame is still valid in presence such a LMC. We find previous estimates LMC's orbital period and apocentric distance derived assuming fixed Milky Way are shortened for models where allowed to move freely response gravitational pull Holding other parameters fixed, fraction favoring...

Vertically extended, high velocity dispersion stellar distributions appear to be a ubiquitous feature of disc galaxies, and both internal external mechanisms have been proposed the major driver their formation. However, it is unclear what extent each mechanism can generate such distribution, which likely depend on assembly history galaxy. To this end, we perform 16 high-resolution cosmological-zoom simulations Milky Way-sized galaxies using state-of-the-art cosmological magnetohydrodynamical...

The magnetic fields observed in the Milky~Way and nearby galaxies appear to be equipartition with turbulent, thermal, cosmic ray energy densities, hence are expected dynamically important. However, origin of these strong is still unclear, most previous attempts simulate galaxy formation from cosmological initial conditions have ignored them altogether. Here, we analyse predicted by simulations Auriga Project, a set 30 high-resolution zoom Milky~Way-like galaxies, carried out moving-mesh...

We present and apply a method to infer the mass of Milky Way (MW) by comparing dynamics MW satellites those model in EAGLE cosmological hydrodynamics simulations. A distribution function (DF) for galactic is constructed from using specific angular momentum energy, which are scaled so as be independent host halo mass. In this 2-dimensional space, orbital properties satellite galaxies vary according The can inferred calculating likelihood that observed population drawn DF. Our robustly...

We present N-body and hydrodynamical simulations of the response Milky Way's baryonic disc to presence Large Magellanic Cloud during a first infall scenario. For fiducial galactic model reproducing gross properties Galaxy, we explore set six initial conditions for LMC varying mass which all evolve fit measured constraints on its current position velocity with respect Galactic Center. find that can produce strong disturbances - warping stellar gaseous discs in without violating from...

The stellar disk of the Milky Way shows complex spatial and abundance structure that is central to understanding key physical mechanisms responsible for shaping our Galaxy. In this study, we use six very high resolution cosmological zoom simulations Way-sized haloes study prevalence formation chemically distinct disc components. We find develop a clearly bimodal distribution in $[\rm \alpha/Fe]$ -- Fe/H]$ plane. two main pathways creating dichotomy which operate different regions galaxies:...

We present the largest number of Milky Way sized dark matter halos simulated at very high mass ($\sim$$10^4$ M$_\odot$/particle) and temporal resolution ($\sim$5 Myrs/snapshot) done to date, quadrupling what is currently available in literature. This initial suite consists first 24 $Caterpillar$ $Project$ (www.caterpillarproject.org) whose project goal 60 - 70 will be made public when complete. resolve $\sim$20,000 gravitationally bound subhalos within virial radius each host halo. Over...

Using the astrometry from ESA's Gaia mission, previous works have shown that Milky Way stellar halo is dominated by metal-rich stars on highly eccentric orbits. To shed light nature of this prominent component, we analysed 28 Galaxy analogues in Auriga suite cosmological hydrodynamics zoom-in simulations. Some three quarters galaxies contain significant components with high radial velocity anisotropy, beta > 0.6. However, only one third hosts do high-beta contribute significantly to accreted...

ABSTRACT We explore the chemodynamical properties of a sample barred galaxies in Auriga magnetohydrodynamical cosmological zoom-in simulations, which form boxy/peanut (b/p) bulges, and compare these to Milky Way (MW). show that best reproduce stellar populations MW bulge have quiescent merger histories since redshift z ∼ 3.5: their last major occurs at $t_{\rm lookback}\gt 12\, \rm Gyr$, while subsequent mergers mass ratio ≤1:20, suggesting an upper limit few per cent for recently proposed...

We analyse a set of cosmological magneto-hydrodynamic simulations the formation Milky Way-mass galaxies identified to have prominent radially anisotropic stellar halo component similar so-called "Gaia Sausage" found in Gaia data. examine effects progenitor Sausage (the Gaia-Enceladus-Sausage, GES) on major galactic components analogous Galactic thick disc and inner halo. find that GES merger is likely been gas-rich contribute 10-50$\%$ gas merger-induced centrally concentrated starburst...

Extremely metal-poor (EMP) stars in the Milky Way (MW) allow us to infer properties of their progenitors by comparing chemical composition metal yields first supernovae. This method is most powerful when applied mono-enriched stars, i.e. that formed from gas was enriched only one previous supernova. We present a novel diagnostic identify this subclass EMP stars. model generations star formation semi-analytically, based on dark matter halo merger trees yield MW-like halos at day. Radiative...

Indications of disequilibrium throughout the Milky Way (MW) highlight need for compact,flexible, non-parametric descriptions phase--space distributions galaxies. We present a new representation current Dark Matter (DM) distribution and potential derived from N-body simulations Large Magellanic Cloud (LMC) system using Basis Function Expansions (BFEs). incorporate methods to maximize physical signal in representation. As result, $10^8$ DM particles representing MW--LMC can be described by 354...

Recent studies have revealed an oscillating asymmetry in the vertical structure of Milky Way's disc. Here, we analyse 16 high-resolution, fully cosmological simulations evolution individual Way-sized galaxies, carried out with magnetohydrodynamic code arepo. At redshift zero, about 70 per cent our galactic discs show strong patterns, amplitudes that can exceed 2 kpc. Half these are typical 'integral sign' warps. The rest oscillations similar to those observed Way. Such structures thus...

ABSTRACT Using a set of 15 high-resolution magnetohydrodynamic cosmological simulations Milky Way formation, we investigate the origin baryonic material found in stars at redshift zero. We find that roughly half this originates from subhalo/satellite systems and is smoothly accreted intergalactic medium. About $90 {{\ \rm per\ cent}}$ all has been ejected re-accreted galactic winds least once. The vast majority gas enters into fountain extends to median galactocentric distance ∼20 kpc with...

ABSTRACT Measurements of the rotation curves dwarf galaxies are often interpreted as requiring a constant density core at centre, odds with ‘cuspy’ inner profiles predicted by N-body simulations cold dark matter (CDM) haloes. It has been suggested that this conflict could be resolved fluctuations in gravitational potential caused periodic removal gas following bursts star formation. Earlier work formation requires bursty and extended history (SFH). Here we investigate structure CDM haloes...

We study the effect of magnetic fields on a simulated galaxy and its surrounding gaseous halo, or circumgalactic medium (CGM), within cosmological 'zoom-in' simulations Milky Way-mass as part 'Simulating Universe with Refined Galaxy Environments' (SURGE) project. use three different formation models, each without fields, include additional spatial refinement in CGM to improve resolution. The central galaxy's star rate stellar mass are not strongly affected by presence but is more...