KINEMATICS OF OUTER HALO GLOBULAR CLUSTERS IN M31

Journal Article · Fri May 10 00:00:00 EDT 2013 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/768/2/L33· OSTI ID:22130668

Veljanoski, J.; Ferguson, A. M. N.; Bernard, E. J.; Penarrubia, J. ^[1]; Mackey, A. D. ^[2]; Huxor, A. P. ^[3]; Irwin, M. J.; Chapman, S. C. ^[4]; Cote, P. ^[5]; Tanvir, N. R.; McConnachie, A. ^[6]; Ibata, R. A.; Martin, N. F. ^[7]; Fardal, M. ^[8]; Lewis, G. F. ^[9]

---

1. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
2. Research School of Astronomy and Astrophysics, Australian National University, Mt Stromlo Observatory, Weston Creek, ACT 2611 (Australia)
3. Astronomisches Rechen-Institut, Zentrum fur Astronomie der Universitat Heidelberg, Monchhofstr. 12-14, D-69120 Heidelberg (Germany)
4. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, British Columbia V9E 2E7 (Canada)
6. Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH (United Kingdom)
7. Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg (France)
8. University of Massachusetts, Department of Astronomy, LGRT 619-E, 710 N. Pleasant Street, Amherst, MA 01003-9305 (United States)
9. Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)

We present the first kinematic analysis of the far outer halo globular cluster (GC) population in the Local Group galaxy M31. Our sample contains 53 objects with projected radii of {approx}20-130 kpc, 44 of which have no previous spectroscopic information. GCs with projected radii {approx}> 30 kpc are found to exhibit net rotation around the minor axis of M31, in the same sense as the inner GCs, albeit with a smaller amplitude of 79 {+-} 19 km s{sup -1}. The rotation-corrected velocity dispersion of the full halo GC sample is 106 {+-} 12 km s{sup -1}, which we observe to decrease with increasing projected radius. We find compelling evidence for kinematic coherence among GCs that project on top of halo substructure, including a clear signature of infall for GCs lying along the northwest stream. Using the tracer mass estimator, we estimate the dynamical mass of M31 within 200 kpc to be M{sub M31} = (1.2-1.5) {+-} 0.2 Multiplication-Sign 10{sup 12} M{sub Sun }. This value is highly dependent on the chosen model and assumptions within.

• OSTI ID: 22130668
• Journal Information: Astrophysical Journal Letters, Vol. 768, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AMPLITUDES
DISPERSIONS
GALAXIES
MASS
ROTATION
STREAMS
VELOCITY