A Two Micron All Sky Survey View of the Sagittarius Dwarf Galaxy. I. Morphology of the Sagittarius Core and Tidal Arms

By S. Majewski, M. Skrutskie, M. Weinberg, J. C. U. O. Virginia, U. Massachusetts. 2003

823 citations recorded by the source corpus.

We present the first all-sky view of the Sagittarius (Sgr) dwarf galaxy mapped by M-giant star tracers detected in the complete Two Micron All Sky Survey (2MASS). Near-infrared photometry of Sgr's prominent M-giant population permits an unprecedentedly clear view of the center of Sgr. The main body is fitted with a King profile of limiting major-axis radius 30°—substantially larger than previously found or assumed—beyond which is a prominent break in the density profile from stars in the Sgr tidal tails; thus the Sgr radial profile resembles that of Galactic dwarf speroidal (dSph) satellites. Adopting traditional methods for analyzing dSph light profiles, we determine the brightness of the main body of Sgr to be MV = -13.27 (the brightest of the known Galactic dSph galaxies) and the total Sgr mass-to-light ratio to be 25 in solar units. However, we regard the latter result with suspicion and argue that much of the observed structure beyond the King-fit core radius (224') may be outside the actual Sgr tidal radius as the former dwarf spiral/irregular satellite undergoes catastrophic disruption during its last orbits. The M-giant distribution of Sgr exhibits a central density cusp at the same location as, but not due to, the old stars constituting the globular cluster M54. A striking trailing tidal tail is found to extend from the Sgr center and arc across the south Galactic hemisphere with approximately constant density and mean distance varying from ~20 to 40 kpc. A prominent leading debris arm extends from the Sgr center northward of the Galactic plane to an apogalacticon ~45 kpc from the Sun and then turns toward the north Galactic cap (NGC), from where it descends back toward the Galactic plane, becomes foreshortened, and, at brighter magnitudes, covers the NGC. The leading and trailing Sgr tails lie along a well-defined orbital plane about the Galactic center. The Sun lies within a kiloparsec of that plane and near the path of leading Sgr debris; thus, it is possible that former Sgr stars are near or in the solar neighborhood. We discuss the implications of this new view of the Sgr galaxy and its entrails for the character of the Sgr orbit, mass, mass-loss rate, and contribution of stars to the Milky Way halo. The minimal precession displayed by the Sgr tidal debris along its inclined orbit supports the notion of a nearly spherical Galactic potential. The number of M giants in the Sgr tails is at least 15% that contained within the King limiting radius of the main Sgr body. The fact that M giants, presumably formed within the past few gigayears in the Sgr nucleus, are nevertheless so widespread along the Sgr tidal arms not only places limits on the dynamical age of these arms but also poses a timing problem that bears on the recent binding energy of the Sgr core and that is most naturally explained by recent and catastrophic mass loss. Sgr appears to contribute more than 75% of the high-latitude, halo M giants, despite substantial reservoirs of M giants in the Magellanic Clouds. No evidence of extended M-giant tidal debris from the Magellanic Clouds is found. Generally good correspondence is found between the M-giant, all-sky map of the Sgr system and all previously published detections of potential Sgr debris, with the exception of Sgr carbon stars, which must be subluminous compared with counterparts in other Galactic satellites in order to resolve the discrepancy.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/f52f0cbbfdcf9abf8507bd56f8276b854140a163

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

Citations in the corpus

STELLAR TIDAL STREAMS IN SPIRAL GALAXIES OF THE LOCAL VOLUME: A PILOT SURVEY WITH MODEST APERTURE TELESCOPES (2010, background): “2) that resemble the Milky Way’s Sagittarius, Orphan and Anticenter streams (e.g., Majewski et al. 2003, Belokurov et al. 2006, 2007b, Grillmair 2006) and (ii) enormous clouds of debris that resemble our current understandings of the expansive Tri-And and Virgo overdensities and the Hercules-Aquila…”
The Milky Way Tomography with SDSS. I. Stellar Number Density Distribution (2005, methodology): “…the contamination byM giants is negligible, because the luminosity difference between red giants and dwarfs is very large (e.g., there are tens of millions of M dwarfs in our sample, while the 2MASS survey revealed only a few thousand M giants in the same region of the sky; Majewski et al. 2003).”
Is the SMC Bound to the LMC? The Hubble Space Telescope Proper Motion of the SMC (2006, background): “…of the Clouds and the Magellanic Stream with tidal streams from other Local Group dwarfs, such as the Sagittarius Stream (Ibata et al. 1994; Majewski et al. 2003), might further constrain the potential of the halo (e.g., Fellhauer et al. 2006; Belokurov et al. 2006; Johnston et al. 2005;…”
THE LEAST-LUMINOUS GALAXY: SPECTROSCOPY OF THE MILKY WAY SATELLITE SEGUE 1 (2008, background): “Majewski et al. (2003) defined a longitudinal coordinate system, Λ⊙, in which the center of the Sgr dSph lies at Λ⊙ = 0.”
The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology (2012, background): “Concerning the MW, the empirical evidence is that its DM halo may be somewhat flattened (oblate) with qd\ 0.8 within Rt 60 kpc (Olling & Merrifield 2000, 2001; Ibata et al. 2001; Majewski et al. 2003; Martı́nezDelgado et al. 2004).”
Redefining the Missing Satellites Problem (2007, background): “The mass modeling of Sagittarius is further complicated by the fact that it is experiencing tidal interactions with the MW (Ibata et al. 1997; Majewski et al. 2003), so a mass estimate from the Jeans equation is not necessarily reliable.”
Tracing Galaxy Formation with Stellar Halos. I. Methods (2005, background): “…of the Sagittarius dwarf galaxy (Ibata, Gilmore, & Irwin 1994; Ibata Gilmore & Irwin 1995) — hereafter Sgr — and its associated trails of debris (see Majewski et al. 2003, for an overview of the many detections) which have now been traced entirely around the Galaxy (Ibata et al. 2001; Majewski…”
Exploring Halo Substructure with Giant Stars: A Diffuse Star Cloud or Tidal Debris around the Milky Way in Triangulum-Andromeda (2004, background): “Recent surveys of the Galactic stellar content (e.g., Ibata et al. 1994, 2002; Majewski et al. 1996, 2003, hereafter M03; Newberg et al. 2002, hereafter N02) have consolidated the notion that galactic mergers play a fundamental role in building our Milky Way (MW).”
Empirical extinction coefficients for the GALEX, SDSS, 2MASS and WISE passbands (2013, methodology): “Downloaded from https://academic.oup.com/mnras/article-abstract/430/3/2188/981583 by guest on 28 July 2018 the R(a) values deduced in this work and those of SFD, Seibert et al. (2005) and Majewski et al. (2003).”
PROBING THE OUTER GALACTIC HALO WITH RR LYRAE FROM THE CATALINA SURVEYS (2012, methodology): “A Monoceros stream has also been discovered (Newberg et al. 2002; Majewski et al 2003) that may be due to the disruption of the putative Canis Major dwarf (CasettiDinescu et al. 2006).”
A Two Micron All-Sky Survey View of the Sagittarius Dwarf Galaxy. IV. Modeling the Sagittarius Tidal Tails (2004, background): “There have been numerous studies reporting the discovery of stars and star clusters plausibly associated with debris from this satellite, either trailing or leading it along its orbit (see Majewski et al. 2003, hereafter Paper I, for a comprehensive summary).”
KINEMATICS OF THE STELLAR HALO AND THE MASS DISTRIBUTION OF THE MILKY WAY USING BLUE HORIZONTAL BRANCH STARS (2012, background): “Discoveries of structures like the Sagittarius dwarf galaxy (Ibata et al. 1994, 1995; Majewski et al. 2003; Belokurov et al. 2006), the Virgo over-density (Juríc et al. 2008), the Triangulum-Andromeda structure (Rocha-Pinto et al. 2004; Majewski et al. 2004; Martin et al. 2007) and the…”
The Metal-poor Halo of the Andromeda Spiral Galaxy (M31) (2006, background): “In the Milky Way, the Sagittarius stream (Ibata et al. 1994; Majewski et al. 2003), the Magellanic stream (Mathewson, Cleary, & Murray 1974) and the Monoceros stream (Yanny et al. 2003) present clear evidence that merging processes are prominent in massive galaxies and are still occuring today.”
The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy (2007, methodology): “However, M54 has been shown (Ibata et al. 1994; Sarajedini & Layden 1995, hereafter SL95; Majewski et al. 2003; Monaco et al. 2005a; Siegel et al. 2006) to lie at the photometric center and distance of the Sagittarius (Sgr) dwarf spheroidal (dSph) galaxy, which is merging with the Milky Way (Ibata…”
Tracing the Galactic Anticenter Stellar Stream with 2MASS M Giants (2003, background): “…Sky Survy (2MASS) database includes the first homogeneous, all-sky photometric survey of Milky Way stars and has already reshaped our understanding of the structure of our Galaxy and its satellite system (e.g., Skrutskie et al. 2001; Weinberg & Nikolaev 2001; Majewski et al. 2003, hereafter M03).”
Precession of the Sagittarius stream (2013, methodology): “We follow the prescription of Majewski et al. (2003) and transform equatorial RA and Dec into a heliocentricΛ⊙, B⊙ coordinate system whose equator is aligned with the Sgr trailing tail.”
Dynamics for galactic archaeology (2013, background): “The most prominent of these is clearly the tidal debris of the Sagittarius dwarf spheroidal galaxy (Majewski et al, 2003; Fellhauer et al., 2007) and SDSS photometry of the vicinity of the globular cluster Palomar 5 allows us to study the process of disruption in detail (Newberg et al., 2002;…”
THE NUCLEUS OF THE SAGITTARIUS DSPH GALAXY AND M54: A WINDOW ON THE PROCESS OF GALAXY NUCLEATION (2008, background): “The tidally stripped stars form a huge and coherent tidal tail system that can be observed over the whole celestial sphere (Sgr Stream, see Ibata et al. 2001; Majewski et al. 2003, and references therein).”