The Galaxy and its stellar halo: insights on their formation from a hybrid cosmological approach

Abstract

We use a series of high-resolution simulations of a `Milky-Way' halo coupled to semi-analytic methods to study the formation of our own Galaxy and of its stellar halo. The physical properties of our model Milky Way, as well as the age and metallicity distribution of stars in the different components, are in relatively good agreement with observational measurements. Assuming that the stellar halo builds up from the cores of the satellite galaxies that merged with the Milky Way over its life-time, we are able to study the physical and structural properties of this component. In agreement with previous work, we find that the largest contribution to the stellar halo should come from a few relatively massive (10^8 - 10^10 Msun) satellites, accreted at early times. Our "stellar halo" does not exhibit any clear metallicity gradient, but higher metallicity stars are more centrally concentrated than stars of lower abundance. This indicates that the probability of observing low-metallicity halo stars increases with distance from the Galactic centre. We find that the proposed "dual" nature of the Galactic stellar halo can be explained in our model as a result of a mass-metallicity relation imprinted in the building blocks of this component.

20 pages, 14 figures. Minor revisions to match version accepted to MNRAS. Version with high-resolution figures available at: http://www.mpa-garching.mpg.de/~lucia/astro-ph/mw_delucia_rev.pdf

References in corpus (16)

• The hierarchical formation of the brightest cluster galaxies
• The Radial Velocity Experiment (RAVE): first data release
• The RAVE Survey: Constraining the Local Galactic Escape Speed
• Two Stellar Components in the Halo of the Milky Way
• A primer on hierarchical galaxy formation: the semi-analytical approach
• The accretion origin of the Milky Way's stellar halo
• The Geneva-Copenhagen Survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk
• A fitting formula for the merger timescale of galaxies in hierarchical clustering
• The high redshift galaxy population in hierarchical galaxy formation models
• The stellar halo of the Galaxy
• Oxygen, Sodium, Magnesium and Aluminium as tracers of the Galactic Bulge Formation
• Modelling galaxy clustering in a high resolution simulation of structure formation
• The Dependence of Galaxy Formation on Cosmological Parameters: Can we distinguish the WMAP1 and WMAP3 Parameter Sets?
• Life and times of dwarf spheroidal galaxies
• Circular velocity profiles of dark matter haloes
• Evolution of stellar-gaseous disks in cosmological haloes

Cited by in corpus (57)

• Is the Milky Way ringing? The hunt for high velocity streams
• The Dragonfly Nearby Galaxies Survey. I. Substantial variation in the diffuse stellar halos around spiral galaxies
• Elemental Abundances in Milky Way-like Galaxies from a Hierarchical Galaxy Formation Model
• Modeling the neutral hydrogen distribution in the post-reionization Universe: intensity mapping
• Galactic Archaeology with Gaia
• Hidden depths in the local Universe: The Stellar Stream Legacy Survey
• Merger-induced galaxy transformations in the ARTEMIS simulations
• Born this way: thin disc, thick disc, and isotropic spheroid formation in FIRE-2 Milky-Way-mass galaxy simulations
• A unified solution to the small scale problems of the $\Lambda$CDM model
• Creating mock catalogues of stellar haloes from cosmological simulations
• Chemical enrichment in very low-metallicity environments: Bootes I
• The distribution of globular clusters in kinematic spaces does not trace the accretion history of the host galaxy
• STEP: The VST survey of the SMC and the Magellanic Bridge. I. Overview and first results
• Does SEGUE/SDSS indicate a dual Galactic halo?
• On the common mass scale of the Milky Way satellites
• Purveyors of fine halos. II. Chemodynamical association of halo stars with Milky Way globular clusters
• Newly Discovered RR Lyrae Stars in the SDSSXPanXSTARRS1XCatalina Footprint
• AGN feedback and the origin of the $\alpha$ enhancement in early type galaxies - insights from the GAEA model
• How cosmological merger histories shape the diversity of stellar haloes
• The observable properties of galaxy accretion events in Milky Way-like galaxies in the FIRE-2 cosmological simulations
• The flat density profiles of massive, and relaxed galaxy clusters
• The stellar halo in Local Group Hestia simulations II. The accreted component
• The diverse X-ray properties of four truly isolated elliptical galaxies: NGC 2954, NGC 6172, NGC 7052, and NGC 7785
• The stellar halo in Local Group Hestia simulations III. Chemical abundance relations for accreted and in-situ stars
• Dark-ages Reionization and Galaxy Formation Simulation -- XVII. Sizes, angular momenta and morphologies of high redshift galaxies
• Possibilities and Limitations of Kinematically Identifying Stars from Accreted Ultra-Faint Dwarf Galaxies
• Building the Stellar Halo Through Feedback in Dwarf Galaxies
• A feather on the hat: Tracing the giant stellar stream around the Sombrero galaxy
• Origin of metals in old Milky Way halo stars based on GALAH and Gaia
• Milky Way type galaxies in a LCDM cosmology
• Effects of chaos on the detectability of stellar streams
• On the Edge: the relation between stellar and dark matter haloes of Milky Way-mass galaxies
• On the dark matter haloes inner structure and galaxy morphology
• Saying Hallo to M94's Stellar Halo: Investigating the Accretion History of the Largest Pseudobulge Host in the Local Universe
• Statistical properties of substructures around Milky Way-sized haloes and their implications for the formation of stellar streams
• Chemical evolution of ultra-faint dwarf galaxies: testing the IGIMF
• Observing the stellar halo of Andromeda in cosmological simulations: the Auriga2PAndAS pipeline
• Jeans that fit: weighing the mass of the Milky Way analogues in the $\Lambda \mathrm{CDM}$ universe
• An optimized Method to Identify RR Lyrae stars in the SDSS X Pan-STARRS1 Overlapping Area Using a Bayesian Generative Technique
• Performance Assessment of the KASI-Deep Rolling Imaging Fast-optics Telescope pathfinder
• On the dwarf galaxies rotation curves diversity problem
• Revealing the Milky Way's Most Recent Major Merger with a Gaia EDR3 Catalog of Machine-Learned Line-of-Sight Velocities
• AuriDESI: Mock Catalogues for the DESI Milky Way Survey
• Building Blocks of the Milky Way's Accreted Spheroid
• RR Lyrae Stars In Stellar Streams with Gaia: The Escapers
• Memoirs of mass accretion: probing the edges of intracluster light in simulated galaxy clusters
• Tomography of stellar halos: what does anisotropy in a stellar halo tell us?
• On the Use of Field RR Lyrae as Galactic Probes -- VIII. Early Formation of the Galactic Spheroid
• Barions and $\Lambda$CDM Model Problems
• Cluster density slopes from Dark Matter-Baryons Energy Transfer
• Accreted stars and stellar haloes of simulated galaxies in TNG50
• Modelling the chemical evolution of the Milky Way
• Probing the spatial and velocity anisotropies in stellar halos from the Aquarius simulations
• Dwarf stellar haloes: a powerful probe of small-scale galaxy formation and the nature of dark matter
• A Tilt in the Dark Matter Halo of the Galaxy
• A Mass Dependent Density Profile from Dwarfs to Clusters
• Towards model-free stellar chemical abundances. Potential applications in the search for chemically peculiar stars in large spectroscopic surveys