The masses of local group dwarf spheroidal galaxies: The death of the universal mass profile

Journal Article · Sat Mar 01 04:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/783/1/7· OSTI ID:22351389

Collins, Michelle L. M.; Martin, Nicolas F. ^[1]; Chapman, Scott C.; Irwin, Michael J. ^[2]; Rich, R. M. ^[3]; Ibata, Rodrigo A. ^[4]; Bate, Nicholas F.; Lewis, Geraint F. ^[5]; Peñarrubia, Jorge ^[6]; Arimoto, Nobuo ^[7]; Casey, Caitlin M. ^[8]; Ferguson, Annette M. N. ^[9]; Koch, Andreas ^[10]; McConnachie, Alan W. ^[11]; Tanvir, Nial ^[12]

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1. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
2. Institute of Astronomy, Madingley Rise, Cambridge, CB3 0HA (United Kingdom)
3. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States)
4. Observatoire de Strasbourg, 11 rue de l'Université, F-67000, Strasbourg (France)
5. Sydney Institute for Astronomy, School of Physics, A28, University of Sydney, NSW 2006 (Australia)
6. Instituto de Astrofísica de Andalucia-CSIC, Glorieta de la Astronomía s/n, E-18008, Granada (Spain)
7. Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States)
8. Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822-1839 (United States)
9. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom)
10. Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, D-69117 Heidelberg (Germany)
11. NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, British Columbia, Victoria V9E 2E7 (Canada)
12. Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

We investigate the claim that all dwarf spheroidal galaxies (dSphs) reside within halos that share a common, universal mass profile as has been derived for dSphs of the galaxy. By folding in kinematic information for 25 Andromeda dSphs, more than doubling the previous sample size, we find that a singular mass profile cannot be found to fit all of the observations well. Further, the best-fit dark matter density profile measured solely for the Milky Way dSphs is marginally discrepant with that of the Andromeda dSphs (at just beyond the 1σ level), where a profile with lower maximum circular velocity, and hence mass, is preferred. The agreement is significantly better when three extreme Andromeda outliers, And XIX, XXI, and XXV, all of which have large half-light radii (≳ 600 pc) and low-velocity dispersions (σ {sub v} < 5 km s{sup –1}), are omitted from the sample. We argue that the unusual properties of these outliers are likely caused by tidal interactions with the host galaxy.

• OSTI ID: 22351389
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 783; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DENSITY
DISPERSIONS
DWARF STARS
GALAXIES
INTERACTIONS
MASS
MILKY WAY
NONLUMINOUS MATTER
VELOCITY
VISIBLE RADIATION