Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies

By M. Walker, M. Mateo, E. Olszewski, O. Gnedin, Xiao Wang, Bodhisattva Sen, Michael Woodroofe. 2007

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We present stellar velocity dispersion profiles for seven Milky Way dwarf spheroidal (dSph) satellite galaxies. We have measured 8394 line-of-sight velocities (±2.5 km s-1) for 6804 stars from high-resolution spectra obtained at the Magellan and MMT telescopes. We combine these new data with previously published velocities to obtain the largest available kinematic samples, which include more than 5500 dSph members. All the measured dSphs have stellar velocity dispersion of order 10 km s-1 that remains approximately constant with distance from the dSph center, out to and in some cases beyond the radius at which the mean surface brightness falls to the background level. Assuming dSphs reside within dark matter halos characterized by the NFW density profile, we obtain reasonable fits to the empirical velocity dispersion profiles. These fits imply that, among the seven dSphs, Mvir ~ 108-109 M☉. The mass enclosed at a radius of 600 pc, the region common to all data sets, lies in the range (2-7) × 107 M☉.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/1020743f06242be8fe9bcd93d736b58196aba0dd

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Citations in the corpus

STELLAR VELOCITIES IN THE CARINA, FORNAX, SCULPTOR, AND SEXTANS dSph GALAXIES: DATA FROM THE MAGELLAN/MMFS SURVEY (2008, methodology): “…of stars per dSph, velocity dispersion profiles are now available for all of the brighter MW dSphs (Kleyna et al. 2002, 2004; Wilkinson et al. 2004; Muñoz et al. 2005, 2006; Sohn et al. 2007; Walker et al. 2006a, 2006b, 2007b; Battaglia et al. 2006; Mateo et al. 2008; Koch et al. 2007b, 2007a).”
The Kinematic Status and Mass Content of the Sculptor Dwarf Spheroidal Galaxy (2008, background): “…appear to be the most dark matter (DM) dominated objects known to date, with mass-tolight (M/L) ratios larger than 100 (e.g., Kleyna et al. 2005; Walker et al. 2007, and references therein); their kinematic status is generally believed to be undisturbed by interactions with the Milky Way (MW),…”
The Most Dark-Matter-dominated Galaxies: Predicted Gamma-Ray Signals from the Faintest Milky Way Dwarfs (2007, background): “Despite the broad range of observed luminosities, the dark matter masses for all of the preSDSS satellites are constrained towithin a relatively narrow range, approximately 1 6 ; 107 M within their inner 600 pc (Walker et al. 2007; Strigari et al. 2007a).”
One Law to Rule Them All: The Radial Acceleration Relation of Galaxies (2016, unknown): “…1: Pietrzyński et al. (2009), 2: Irwin & Hatzidimitriou (1995), 3: Walker et al. (2009c), 4: Bonanos et al. (2004), 5: Martin et al. (2008), 6: Walker et al. (2007), 7: Bellazzini et al. (2004), 8: Mateo et al. (2008), 9: Bellazzini et al. (2005), 10: Koch et al. (2007), 11: Pietrzyński et…”
A QUANTITATIVE EXPLANATION OF THE OBSERVED POPULATION OF MILKY WAY SATELLITE GALAXIES (2009, methodology): “With a model that assigns stellar luminosities to each satellite halo, we can predict the expected stellar velocity dispersions for comparison with those measured for MW satellites by Walker et al. (2007), Simon & Geha (2007), and Martin et al. (2007).”
The impact of dark matter cusps and cores on the satellite galaxy population around spiral galaxies (2010, methodology): “This approximation is valid for the large majority of satellite galaxies, i.e. dwarf galaxies, which typically show very high mass-to-light ratios (Aaronson 1983, Aaronson & Olszewski 1987; Mateo 1998; Walker et al. 2007; Simon & Geha 2007; Strigari et al. 2008; Peñarrubia et al. 2008a).”
Gravitational probes of dark matter physics (2017, background): “For somewhat larger objects, like the classical dwarf satellites of the Milky Way (with stellar mass M∗ & 10(5)M , many of which were recently star-forming) or the late-type (spiral) dwarf galaxies in the Little Things surveys [250, 251] (Mhalo∼ 10(10)M − 10(11)M ), it is clear that their central de”
A METHOD FOR MEASURING (SLOPES OF) THE MASS PROFILES OF DWARF SPHEROIDAL GALAXIES (2011, background): “Furthermore, given the general flatness of dSph velocity dispersion profiles (Walker et al. 2007b), the value of this mass relates simply to the product of velocity dispersion and the halflight radius of the adopted surface brightness model.”
Formation of isolated dwarf galaxies with feedback (2009, methodology): “This is comparable to the observed range of 7 to 10 kms−1 for six of the seven ‘classical’ Local Group dwarf spheroidals in the sample of Walker et al. (2007).”
Dark Matter Subhalos and the Dwarf Satellites of the Milky Way (2008, unknown): “6 values from Walker et al. (2007).”
The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run? (2007, methodology): “This model agrees reasonably well with the distribution of velocities of other nonYLeo I stars plotted in Figure 9 and does very well in other dSph fields (Walker et al. 2007b).”
The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, methodology): “The M/L ratios were computed using the masses derived by Walker et al. (2007); Battaglia et al. (2008); Kleyna et al. (2004).”
ACCURATE STELLAR KINEMATICS AT FAINT MAGNITUDES: APPLICATION TO THE BOÖTES I DWARF SPHEROIDAL GALAXY (2011, methodology): “The standard approach used for the measurement of stellar velocities (Hargreaves, Gilmore, et al. 1994; Koch et al. 2007; Simon & Geha 2007; Walker et al. 2007; Baumgardt et al. 2009; Geha et al. 2009; Leaman et al. 2009; Koch et al. 2009) has been to crosscorrelate against a template spectrum…”