The Next Generation Virgo Cluster Survey. V. modeling the dynamics of M87 with the made-to-measure method
- National Astronomical Observatories, Chinese Academy of Sciences, A20 Datun Rd, Chaoyang District, Beijing 100012 (China)
- Department of Astronomy, Peking University, Beijing 100871 (China)
- Department of Physics and Astronomy, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
- National Research Council of Canada, Victoria, BC V9E 2E7 (Canada)
- Canada-France-Hawaii Telescope Corporation, Kamuela, HI 96743 (United States)
- Department of Physics and Astronomy, Youngstown State University, One University Plaza, Youngstown, OH 44555 (United States)
- Université de Lyon 1, CRAL, Observatoire de Lyon, 9 av. Charles André, F-69230 Saint-Genis Laval, CNRS, UMR 5574, ENS de Lyon (France)
- Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 7820436 Macul, Santiago (Chile)
- Observatoire astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 rue de l'Universite, F-67000 Strasbourg (France)
- GEPI, Observatoire de Paris, 77 av. Denfert Rochereau, F-75014 Paris (France)
We study the dynamics of the giant elliptical galaxy M87 from the central to the outermost regions with the made-to-measure (M2M) method. We use a new catalog of 922 globular cluster line-of-sight velocities extending to a projected radius of 180 kpc (equivalent to 25 M87 effective radii), and SAURON integral field unit data within the central 2.4 kpc. There are 263 globular clusters, mainly located beyond 40 kpc, newly observed by the Next Generation Virgo Survey. For the M2M modeling, the gravitational potential is taken as a combination of a luminous matter potential with a constant stellar mass-to-light ratio and a dark matter potential modeled as a logarithmic potential. Our best-fit dynamical model returns a stellar mass-to-light ratio in the I band of M/L{sub I} = 6.0 ± 0.3 M{sub ⊙} L{sub ⊙}{sup −1} with a dark matter potential scale velocity of 591 ± 50 km s{sup –1} and scale radius of 42 ± 10 kpc. We determine the total mass of M87 within 180 kpc to be (1.5 ± 0.2) × 10{sup 13} M {sub ☉}. The mass within 40 kpc is smaller than previous estimates determined using globular cluster kinematics that did not extend beyond ∼45 kpc. With our new globular cluster velocities at much larger radii, we see that globular clusters around 40 kpc show an anomalously large velocity dispersion which affected previous results. The mass we derive is in good agreement with that inferred from ROSAT X-ray observation out to 180 kpc. Within 30 kpc our mass is also consistent with that inferred from Chandra and XMM-Newton X-ray observations, while within 120 kpc it is about 20% smaller. The model velocity dispersion anisotropy β parameter for the globular clusters in M87 is small, varying from –0.2 at the center to 0.2 at ∼40 kpc, and gradually decreasing to zero at ∼120 kpc.
- OSTI ID:
- 22365193
- Journal Information:
- Astrophysical Journal, Vol. 792, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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