Revealing Substructure in the Galactic Halo - The SEKBO RR Lyrae Survey

Abstract

We present a search for RR Lyrae variable stars from archival observations of the Southern Edgeworth-Kuiper Belt Object survey. The survey covers 1675 square degrees along the ecliptic to a mean depth of V=19.5, i.e. a heliocentric distance of ~50kpc for RR Lyrae stars. The survey reveals 2016 RR Lyrae candidates. Follow-up photometric monitoring of a subset of these candidates shows (24+/-12)% contamination by non-RR Lyrae variables. We derive a map of over-density of RR Lyraes in the halo that reveals a series of structures coincident with the leading and trailing arms of debris from the Sagittarius dwarf galaxy. One of the regions of over-density is found on the trailing arm, 200 deg. from the main body of the Sagittarius dwarf at a distance of ~45kpc. This distant detection of the stellar population of the outer trailing arm of Sagittarius offers a tight constraint on the motion of the dwarf galaxy. A distinctly separate region of over-density is seen towards the Virgo Over Density.

59 pages, 21 figures. ApJ accepted

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• The Stellar Halo in the Inner Milky Way: Predicted Shape and Kinematics
• A comprehensive view of the Virgo Stellar Stream
• The Outer Halo of the Milky Way as Probed by RR Lyr Variables from the Palomar Transient Facility
• Probing the Galactic Halo with RR Lyrae Stars. II. The Substructures of the Milky Way
• The stellar halo of the Milky Way traced by blue horizontal-branch stars in the Subaru Hyper Suprime-Cam Survey
• RR Lyrae in XSTPS: The halo density profile in the North Galactic Cap
• Newly Discovered RR Lyrae Stars in the SDSSXPanXSTARRS1XCatalina Footprint
• Stellar over-densities in the halo: the extent of the Virgo over-density
• On the Use of Field RR Lyrae as Galactic Probes. V. Optical and radial velocity curve templates
• The RR Lyrae projected density distribution from the Galactic centre to the halo
• The Identification of RR Lyrae and Delta Scuti Stars from Variable GALEX Ultraviolet Sources
• An optimized Method to Identify RR Lyrae stars in the SDSS X Pan-STARRS1 Overlapping Area Using a Bayesian Generative Technique
• RR Lyrae stars as probes of the outer Galactic halo: Chemical and kinematic analysis of a pilot sample
• A Hint of Three-section Halo as Seen from the APOGEE DR14