Detection of satellite remnants in the Galactic Halo with Gaia III. Detection limits for Ultra Faint Dwarf Galaxies

Abstract

We present a method to identify Ultra Faint Dwarf Galaxy (UFDG) candidates in the halo of the Milky Way using the future Gaia catalogue and we explore its detection limits and completeness. The method is based on the Wavelet Transform and searches for over-densities in the combined space of sky coordinates and proper motions, using kinematics in the search for the first time. We test the method with a Gaia mock catalogue that has the Gaia Universe Model Snapshot (GUMS) as a background, and use a library of around 30 000 UFDGs simulated as Plummer spheres with a single stellar population. For the UFDGs we use a wide range of structural and orbital parameters that go beyond the range spanned by real systems, where some UFDGs may remain undetected. We characterize the detection limits as function of the number of observable stars by Gaia in the UFDGs with respect to that of the background and their apparent sizes in the sky and proper motion planes. We find that the addition of proper motions in the search improves considerably the detections compared to a photometric survey at the same magnitude limit. Our experiments suggest that Gaia will be able to detect UFDGs that are similar to some of the known UFDGs even if the limit of Gaia is around 2 magnitudes brighter than that of SDSS, with the advantage of having a full-sky catalogue. We also see that Gaia could even find some UFDGs that have lower surface brightness than the SDSS limit.

Accepted for publication in MNRAS

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• Dark matters on the scale of galaxies
• Abundance matching with the mean star formation rate: there is no missing satellites problem in the Milky Way above ${\mathbf{M}}_{200}\sim 10^9{\mathbf{M}}_{\odot }$
• Galactic Archaeology with Gaia
• An all-sky proper motion map of the Sagittarius stream using Gaia DR2
• The phase spiral in Gaia DR3
• Indirect dark matter searches in the dwarf satellite galaxy Ursa Major II with the MAGIC Telescopes
• The ISLAnds Project III: Variable Stars in Six Andromeda Dwarf Spheroidal Galaxies
• Spectral and spatial analysis of the dark matter subhalo candidates among Fermi Large Area Telescope unidentified sources
• New detections of embedded clusters in the Galactic halo
• A Gaia DR2 search for dwarf galaxies towards Fermi-LAT sources: implications for annihilating dark matter
• Searching for Dwarf Galaxies in $Gaia$ DR2 Phase-Space Data Using Wavelet Transforms
• Hunt for dark subhalos in the galactic stellar field using computer vision