A KINEMATIC STUDY OF THE ANDROMEDA DWARF SPHEROIDAL SYSTEM

By M. Collins, S. Chapman, R. Rich, R. Ibata, N. Martin, M. Irwin, N. Bate, Geraint F. Lewis, J. Peñarrubia, N. Arimoto and 5 more. 2013

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We present a homogeneous kinematic analysis of red giant branch stars within 18 of the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using the Keck I/LRIS and Keck II/DEIMOS spectrographs. Based on their g − i colors (taken with the CFHT/MegaCam imager), physical positions on the sky, and radial velocities, we assign probabilities of dSph membership to each observed star. Using this information, the velocity dispersions, central masses, and central densities of the dark matter halos are calculated for these objects, and compared with the properties of the Milky Way dSph population. We also measure the average metallicity ([Fe/H]) from the co-added spectra of member stars for each M31 dSph and find that they are consistent with the trend of decreasing [Fe/H] with luminosity observed in the Milky Way population. We find that three of our studied M31 dSphs appear as significant outliers in terms of their central velocity dispersion, And XIX, XXI, and XXV, all of which have large half-light radii (≳ 700 pc) and low velocity dispersions (σv < 5 km s−1). In addition, And XXV has a mass-to-light ratio within its half-light radius of just , making it consistent with a simple stellar system with no appreciable dark matter component within its 1σ uncertainties. We suggest that the structure of the dark matter halos of these outliers have been significantly altered by tides.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/6452fbfff8620eafc0f9bc739c72a7239ad771d1

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Citations in the corpus

A HIGH STELLAR VELOCITY DISPERSION AND ∼100 GLOBULAR CLUSTERS FOR THE ULTRA-DIFFUSE GALAXY DRAGONFLY 44 (2016, background): “It has been suggested that tides were responsible for creating some of the largest and faintest galaxies in the Local Group 1 Astronomy Department, Yale University, New Haven, CT 06511, USA 2 Department of Astronomy & Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Ca”
One Law to Rule Them All: The Radial Acceleration Relation of Galaxies (2016, methodology): “…(2005), 20 21 49: Geha et al. (2006), 50: McConnachie & Irwin (2006), 51: Tollerud et al. (2012), 52: Ho et al. (2012), 53: Chapman et al. (2007), 54: Collins et al. (2013), 55: Brasseur et al. (2011), 56: Kalirai et al. (2009), 57: Collins et al. (2015), 58: McConnachie et al. (2008), 59:…”
The Local Group on FIRE: dwarf galaxy populations across a suite of hydrodynamic simulations (2018, unknown): “…(2006); (27) Tollerud et al. (2012); (28) Martin et al. (2013a); (29) Conn et al. (2012); (30) Ho et al. (2012); (31) Richardson et al. (2011); (32) Collins et al. (2013); (33) Martin et al. (2009); (34) Cook et al. (1999); (35) Ibata et al. (2007); (36) McConnachie et al. (2008); (37) Brasseur…”
WHY BARYONS MATTER: THE KINEMATICS OF DWARF SPHEROIDAL SATELLITES (2012, methodology): “We predict that only satellite galaxies that have experienced substantial mass loss via tidal stripping should reach the lowest observed vc values at a fixed luminosity (see also Collins et al. 2013b).”
Core formation in dwarf haloes with self-interacting dark matter: no fine-tuning necessary (2014, methodology): “…for the purely dispersion galaxies are calculated using the Wolf et al. (2010) formula, where measurements for stellar velocity dispersion, σ?, are taken from Hoffman et al. (1996), Simon & Geha (2007), Epinat et al. (2008), Fraternali et al. (2009), Collins et al. (2013), and Kirby et al. (2014).”
Too big to fail in the Local Group (2014, background): “Velocity dispersions for the two Andromeda dwarfs with constraints on σ that meet the distance cuts are from Collins et al. (2013).”
Quenching and ram pressure stripping of simulated Milky Way satellite galaxies (2017, background): “Also, M31 contains several dwarf spheroidal (dSph) galaxies with unusually large half-light radii compared to MW dSphs (Collins et al. 2013).”
Is there a "too big to fail" problem in the field? (2014, background): “…and environmental mechanisms (such as photoionization feedback, tidal and ram-pressure stripping, etc.;e.g Okamoto et al. 2008; Arraki et al. 2014; Zolotov et al. 2012; Collins et al. 2013; Kravtsov et al. 2004) that are expected to inhibit the formation of galaxies in the smallest MW subhalos.”