Exposing sgr tidal debris behind the galactic disc with M giants selected in WISE∩2MASS

S. E. Koposov, V. Belokurov, D. B. Zucker, G. F. Lewis, R. A. Ibata, E. W. Olszewski, A. R. Loṕez-Sańchez, E. A. Hyde

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We show that a combination of infrared photometry from WISE and 2MASS surveys can yield highly pure samples of M giant stars. We take advantage of the new WISEn2MASS M giant selection to trace the Sagittarius (Sgr) trailing tail behind the Galactic disc in the direction of the anticentre. The M giant candidates selected via broad-band photometry are confirmed spectroscopically using AAOmega on the Anglo-Australian Telescope in three fields around the extremity of the Sgr trailing tail in the Southern Galactic hemisphere.We demonstrate that at the Sgr longitude (n-ary logical and) ⊙ = 204°, the line-of-sight velocities of the trailing tail starts to deviate from the track of the Law & Majewski model, confirming the prediction of Belokurov et al. This discovery serves to substantiate the measurement of low differential orbital precession of the Sgr stream which in turn may imply diminished dark matter content within 100 kpc.

Original languageEnglish (US)
Pages (from-to)3110-3117
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - 2015


  • Galaxies: Dwarf
  • Galaxies: Kinematics and dynamics
  • Galaxy: Halo
  • Galaxy: Kinematics and dynamics
  • Stars: General
  • Stars: Kinematics and dynamics

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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