The Origin of the Bifurcation in the Sagittarius Stream

Abstract

The latest Sloan Digital Sky Survey data reveal a prominent bifurcation in the distribution of debris of the Sagittarius dwarf spheroidal (Sgr) beginning at a right ascension of roughly 190 degrees. Two branches of the stream (A and B) persist at roughly the same heliocentric distance over at least 50 degrees of arc. There is also evidence for a more distant structure (C) well behind the A branch. This paper provides the first explanation for the bifurcation. It is caused by the projection of the young leading (A) and old trailing (B) tidal arms of the Sgr, whilst the old leading arm (C) lies well behind A. This explanation is only possible if the halo is close to spherical, as the angular difference between the branches is a measure of the precession of the orbital plane.

arXiv commentApJ, in press

References in corpus (24)

• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The u'g'r'i'z' Standard Star Network
• The Fourth Data Release of the Sloan Digital Sky Survey
• Simulations of X-ray Clusters
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: I. Morphology of the Sagittarius Core and Tidal Arms
• The Field of Streams: Sagittarius and its Siblings
• Astrometric Calibration of the Sloan Digital Sky Survey
• The Ghost of Sagittarius and Lumps in the Halo of the Milky Way
• A photometricity and extinction monitor at the Apache Point Observatory
• SDSS Data Management and Photometric Quality Assessment
• Great Circle tidal streams: evidence for a nearly spherical massive dark halo around the Milky Way
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: IV. Modeling the Sagittarius Tidal Tails
• The Kinematics, Orbit, and Survival of the Sagittarius Dwarf Spheroidal Galaxy
• The Assembly of Galaxies in a Hierarchically Clustering Universe
• The Universal Mass Accretion History of CDM Haloes
• Galactic Halo substructure in the Sloan Digital Sky Survey: the ancient tidal stream from the Sagittarius dwarf galaxy
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: III. Constraints on the Flattening of the Galactic Halo
• Velocity trends in the debris of Sagittarius and the shape of the dark-matter halo of the Galaxy
• Sagittarius Tidal Debris 90 kpc from the Galactic Center
• Two measures of the shape of the Milky Way's dark halo
• A Two Micron All-Sky Survey View of the Sagittarius Dwarf Galaxy: II. Swope Telescope Spectroscopy of M Giant Stars in the Dynamically Cold Sagittarius Tidal Stream
• Superbox - An Efficient Code for Collisionless Galactic Dynamics
• Is the dark halo of our Galaxy spherical?
• Something about the structure of the Galaxy

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