The Origin of the Bifurcation in the Sagittarius Stream

By M. Fellhauer, V. Belokurov, N. Evans II, M. Wilkinson, D. Zucker, G. Gilmore, M. Irwin, D. Bramich, S. Vidrih, R. Wyse and 5 more. 2006

204 citations recorded by the source corpus.

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 α ≈ 190°. Two branches of the stream (A and B) persist at roughly the same heliocentric distance over at least 50° 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, while 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.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Galaxies as simple dynamical systems: observational data disfavor dark matter and stochastic star formation (2014, methodology): “The Sagittarius (Sgr) satellite galaxy of the MW Attempts at fitting the large number of observational constraints on the Sgr streams which are available over the past three orbits of the satellite have used models in which Sgr has a stellar mass of about 10 − 10M but no or only a minor dark matter ”
CLUMPY STREAMS FROM CLUMPY HALOS: DETECTING MISSING SATELLITES WITH COLD STELLAR STRUCTURES (2010, result): “However, further simulations of an Sgr-scale stream (much longer and thicker than our Pal-5-like test case) are needed to confirm the plausibility of this scenario and distinguish it from other explanations of this bifurcation (e.g. Fellhauer et al. 2006; Peñarrubia et al. 2010).”
THE SAGITTARIUS DWARF GALAXY: A MODEL FOR EVOLUTION IN A TRIAXIAL MILKY WAY HALO (2010, methodology): “In both the model presented here and the model described by Fellhauer et al. (2006), the T1 wrap traverses this region from α ∼ 120◦ to α ∼ 220◦ with a distance varying from ∼ 40 kpc to ∼ 20 kpc, and radial velocity varying from ∼ 125 km s−1 to ∼ −125 km s−1 .”
ASSESSING THE MILKY WAY SATELLITES ASSOCIATED WITH THE SAGITTARIUS DWARF SPHEROIDAL GALAXY (2010, background): “Belokurov et al. (2009) note that Coma Ber is superimposed on the edge of the Sgr stream at a distance that suggests association with the ‘C’ wrap of Sgr debris in the model of Fellhauer et al. (2006).”
A COMPLETE SPECTROSCOPIC SURVEY OF THE MILKY WAY SATELLITE SEGUE 1: THE DARKEST GALAXY (2010, background): “NO09 pointed out that the Fellhauer et al. (2006) model predicts that there are also Sgr stars stripped several orbits earlier at this position that have velocities similar to Segue 1.”
Local-Group tests of dark-matter concordance cosmology - Towards a new paradigm for structure formation (2010, methodology): “However, there is still much uncertainty and disagreement as to the shape and orientation of the MW DM halo: Fellhauer et al. (2006) used the bifurcation of the Sagittarius stream to constrain the shape of the MW DM halo to within about 60 kpc, finding it to be close to spherical.”
Is the SMC Bound to the LMC? The Hubble Space Telescope Proper Motion of the SMC (2006, background): “However, a significant departure from spherical symmetry would induce a precession in the orbital plane of a satellite (e.g., Fellhauer et al. 2006).”
`Skinny Milky Way please', says Sagittarius (2014, methodology): “Second, the Sgr disruption could have been going on for so long (see e.g. Fellhauer et al. 2006) that the Galaxy’s mass distribution has evolved.”
The Causes of Halo Shape Changes Induced by Cooling Baryons: Disks versus Substructures (2007, background): “Observational constraints on halo shapes can be obtained from the Milky Way (Ibata et al. 2001; Johnston et al. 2005; Helmi 2004; Fellhauer et al. 2006), from polar ring galaxies (Schweizer et al. 1983; Sackett & Sparke 1990; Iodice et al. 2003), from X-ray isophotal shapes (Buote & Canizares 1994;…”
Limits on the Macho Content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds (2006, background): “Constraints on the shape of the Milky Way halo were recently summarized by Fellhauer et al. (2006) who argued that the observed bifurcation of the Sagittarius Stream can be explained if the halo is close to spherical.”
The total mass of the Large Magellanic Cloud from its perturbation on the Orphan stream (2018, background): “Moreover, streams are sensitive probes of the shape of the underlying potential (see Ibata et al. 2001; Helmi 2004; Johnston, Law & Majewski 2005; Fellhauer et al. 2006; Law & Majewski 2010; Bowden, Belokurov & Evans 2015) and their twisting and fanning can be used to understand the amount of…”
KINEMATICAL AND CHEMICAL VERTICAL STRUCTURE OF THE GALACTIC THICK DISK. II. A LACK OF DARK MATTER IN THE SOLAR NEIGHBORHOOD, (2012, methodology): “…constraints on the DM halo shape are scarce and often controversial and, while spherical structures are usually preferred (e.g. Ibata et al. 2001; Majewski et al. 2003; Johnston et al. 2005; Fellhauer et al. 2006), a prolate spheroid (q = 5/3) was invoked by Helmi (2004) and Law et al. (2005).”
Precession of the Sagittarius stream (2013, background): “…remains largely unstudied, yeta broadbrush picture of the wide and luminous Sgr stream is slowly taking shape, thanks to the diversity of the disruption models at hand (e.g. Ibata et al. 2001; Helmi 2004; Johnston et al. 2005; Fellhauer et al. 2006; Law & Majewski 2010; Peñarrubia et al. 2010).”
THE LEAST-LUMINOUS GALAXY: SPECTROSCOPY OF THE MILKY WAY SATELLITE SEGUE 1 (2008, background): “Figure 5 (left panel) illustrates the previously noted spatial alignment of the Segue 1 field with the leading Sgr stream (i.e. the ‘A’ and ‘C’ streams of Fellhauer et al. (2006)).”
Substructure revealed by RR Lyraes in SDSS Stripe 82 (2009, background): “Our identifications are tentative and radial velocity data is required to enable a cleaner separation of the wraps, as is evident from the lower panel of Figure 3 of Fellhauer et al. (2006).”
The VPOS: a vast polar structure of satellite galaxies, globular clusters and streams around the Milky Way (2012, result): “Sagittarius: The orbital plane of the Sagittarius stellar stream was analysed in great detail (Majewski et al. 2003; Fellhauer et al. 2006) and is in very good agreement with the orbital pole of the satellite galaxy.”
CONSTRAINING THE MILKY WAY POTENTIAL WITH A SIX-DIMENSIONAL PHASE-SPACE MAP OF THE GD-1 STELLAR STREAM (2009, methodology): “We adopt a three-component model of the Galaxy po- tential, choosing one that is widely used in the modeling of the Sgr stream (Helmi 2004; Law et al. 2005; Fellhauer et al. 2006) and reproduces the galactic rotation curve reasonably well.”
The spatial distribution of the Milky Way and Andromeda satellite galaxies (2006, methodology): “Furthermore, recent measurements of the shape of the MW potential using the Sagittarius stream show it to be spherical within about 60 kpc (Fellhauer et al. 2006).”