Detection of satellite remnants in the Galactic Halo with Gaia - I. The effect of the Galactic background, observational errors and sampling

Abstract

We address the problem of identifying remnants of satellite galaxies in the halo of our galaxy with Gaia data. The remnants have to be extracted from a very large data set (of order 10^9 stars) in the presence of observational errors and against a background population of Galactic stars. We address this issue through a numerical simulation of the Gaia catalogue with a realistic number of entries. The Galaxy model includes separate light distributions and kinematics for the bulge, disc and stellar halo. Our catalogue contains 3.5x10^8 stars. We perform tree code 10^6-body simulations of satellite dwarf galaxies in orbit around a rigid mass model of the Galaxy. The shrinking satellite cores and tidal tails are added to the Monte Carlo simulation of the Gaia catalogue. When combining the Milky Way and dwarf galaxy models we include the complication that the luminosity function of the satellite is probed at various depths as a function of position along the tidal tails. The combined models are converted to a synthetic Gaia catalogue using a detailed model for the expected astrometric and radial velocity errors, depending on magnitude, colour and sky position of the stars. We explore the feasibility of detecting tidal streams in the halo using the energy versus angular momentum plane. A straightforward search in this plane will be very challenging. The background population and the observational errors make it difficult to detect tidal streams as discrete structures in the E-Lz plane. The propagation of observational errors leads to apparent caustic structures in the integrals of motion space that may be mistaken for physical entities. Any practical search strategy will have to use a combination of pre-selection of high-quality data and complementary searches using the photometric data from Gaia. (abridged)

arXiv comment20 pages, 24 postscript figures, accepted for publication in MNRAS

References in corpus (38)

• The Sloan Digital Sky Survey: Technical Summary
• A Universal Density Profile from Hierarchical Clustering
• Dark Matter Substructure in Galactic Halos
• Where are the missing galactic satellites?
• Evolutionary tracks and isochrones for low- and intermediate-mass stars: from 0.15 to 7 M_sun, and from Z=0.0004 to 0.03
• Dwarf Galaxies of the Local Group
• Hierarchical Galaxy Formation
• Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets
• The New Galaxy: Signatures of its Formation
• GAIA: Composition, Formation and Evolution of the Galaxy
• Semi-Analytic Modelling of Galaxy Formation: The Local Universe
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
• Debris streams in the solar neighbourhood as relicts from the formation of the Milky Way
• Great Circle tidal streams: evidence for a nearly spherical massive dark halo around the Milky Way
• Building up the Stellar Halo of the Galaxy
• Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART
• A dwarf galaxy remnant in Canis Major: the fossil of an in-plane accretion onto the Milky Way
• Sinking Satellites and the Heating of Galaxy Discs
• Fossil Signatures of Ancient Accretion Events in the Halo
• The Disruption of the Sagittarius Dwarf Galaxy.
• The Effect of Dissipation on the Shapes of Dark halos
• Velocity trends in the debris of Sagittarius and the shape of the dark-matter halo of the Galaxy
• Mapping the substructure in the Galactic halo with the next generation of astrometric satellites
• Exploring Halo Substructure with Giant Stars: A diffuse star cloud or tidal debris around the Milky Way in Triangulum-Andromeda
• A Parallel Tree Code
• Exploring Halo Substructure with Giant Stars: I. Survey Description and Calibration of the Photometric Search Technique
• Tracing out the Northern Tidal Stream of the Sagittarius Dwarf Spheoridal Galaxy
• Mapping the Galactic Halo I. The `Spaghetti' Survey
• Exploring Halo Substructure with Giant Stars IV: The Extended Structure of the Ursa Minor Dwarf Spheroidal
• The phase-space structure of cold dark-matter halos: Insights into the Galactic halo
• Dark Matter in Dwarf Spheroidals I: Models
• Spectroscopic survey of the Galaxy with Gaia I. Design and performance of the Radial Velocity Spectrometer
• SPIFFI observations of the starburst SMMJ14011+0252: Already old, fat, and rich by z = 2.565
• Shapes of dark matter halos
• A Disk Galaxy of Old Stars at z ~ 2.5
• The Faint Optical Stellar Luminosity Function in the Ursa Minor Dwarf Spheroidal Galaxy
• On the Hipparcos parallaxes of O stars

Cited by in corpus (27)

• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• Galaxia: a code to generate a synthetic survey of the Milky Way
• One large blob and many streams frosting the nearby stellar halo in Gaia DR2
• On the kinematic detection of accreted streams in the Gaia era: a cautionary tale
• On the identification of merger debris in the {\it Gaia} Era
• Decoding the stellar fossils of the dusty Milky Way progenitors
• Galactic Archaeology with Gaia
• Modeling Tidal Streams in evolving dark matter halos
• The expected performance of stellar parametrization with Gaia spectrophotometry
• Constraints on the assembly history of the Milky Way's smooth, diffuse stellar halo from the metallicity-dependent, radially-dominated velocity anisotropy profiles probed with K giants and BHB stars using LAMOST, SDSS/SEGUE, and Gaia
• A statistical method for measuring the Galactic potential and testing gravity with cold tidal streams
• Statistical detection of a tidal stream associated with the globular cluster M68 using Gaia data
• Analysing surveys of our Galaxy I: basic astrometric data
• Turbulence in the Intergalactic Medium
• A Two-Point Correlation Function For Galactic Halo Stars
• Metallicity distributions of halo stars: do they trace the Galactic accretion history?
• Characterizing the Galactic warp with Gaia: I. The tilted ring model with a twist
• Galactic googly: the rotation-metallicity bias in the inner stellar halo of the Milky Way
• Detection of satellite remnants in the Galactic Halo with Gaia III. Detection limits for Ultra Faint Dwarf Galaxies
• Predictions for the detection of Tidal Streams with Gaia using Great Circle Methods
• Detection of Satellite Remnants in the Galactic Halo with Gaia - II. A modified Great Circle Cell Method
• Dynamical invariants and diffusion of merger substructures in time-dependent gravitational potentials
• Extracting science from surveys of our Galaxy
• Constraining dark matter sub-structure with the dynamics of astrophysical systems
• Jeans that fit: weighing the mass of the Milky Way analogues in the $\Lambda \mathrm{CDM}$ universe
• How well can we unravel the accreted constituents of the Milky Way stellar halo? A test on cosmological hydrodynamical simulations
• What will Gaia tell us about the Galactic disk?