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Modeling mass independent of anisotropy

Published online by Cambridge University Press:  12 August 2011

Joe Wolf*
Affiliation:
Center for Cosmology, Department of Physics & Astronomy, University of California, Irvine, CA 92697wolfj@uci.edu
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Abstract

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By manipulating the spherical Jeans equation, Wolf et al. (2010) show that the mass enclosed within the 3D deprojected half-light radius r1/2 can be determined with only mild assumptions about the spatial variation of the stellar velocity dispersion anisotropy as long as the projected velocity dispersion profile is fairly flat near the half-light radius, as is typically observed. They find M1/2 = 3 G−1 〈σ2los〉 r1/2 ≃ 4 G−1 〈σ2los〉 Re, where 〈σ2los〉 is the luminosity-weighted square of the line-of-sight velocity dispersion and Re is the 2D projected half-light radius. This finding can be used to show that all of the Milky Way dwarf spheroidal galaxies (MW dSphs) are consistent with having formed within a halo of mass approximately 3 × 109 M, assuming a ΛCDM cosmology. In addition, the dynamical I-band mass-to-light ratio ϒI1/2 vs. M1/2 relation for dispersion-supported galaxies follows a U-shape, with a broad minimum near ϒI1/2 ≃ 3 that spans dwarf elliptical galaxies to normal ellipticals, a steep rise to ϒI1/2 ≃ 3,200 for ultra-faint dSphs, and a more shallow rise to ϒI1/2 ≃ 800 for galaxy cluster spheroids.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

Battaglia, G. et al. 2005, MNRAS, 364, 433CrossRefGoogle Scholar
Binney, J. & Mamon, G. A. 1982, MNRAS, 200, 361CrossRefGoogle Scholar
Bullock, J. S., Kolatt, T. S., Sigad, Y., Somerville, R. S., Kravtsov, A. V., Klypin, A. A., Primack, J. R., & Dekel, A. 2001, MNRAS, 321, 559CrossRefGoogle Scholar
Bullock, J. S., Stewart, K. R., Kaplinghat, M., Tollerud, E. J., & Wolf, J. 2010, ApJ, 717, 1043CrossRefGoogle Scholar
Dehnen, W., McLaughlin, D. E., & Sachania, J. 2006, MNRAS, 369, 1688CrossRefGoogle Scholar
Dekel, A., Stoehr, F., Mamon, G. A., Cox, T. J., Novak, G. S., & Primack, J. R. 2005, Nature, 437, 707CrossRefGoogle Scholar
Gilmore, G., Wilkinson, M. I., Wyse, R. F. G., Kleyna, J. T., Koch, A., Evans, N. W., & Grebel, E. K. 2007, ApJ, 663, 948CrossRefGoogle Scholar
Kalirai, J. S. et al. 2010, ApJ, 711, 671CrossRefGoogle Scholar
Łokas, E. L. 2009, MNRAS, 394, L102CrossRefGoogle Scholar
Macciò, A. V., Dutton, A. A. & van den Bosch, F. C. 2008, MNRAS, 391, 1940CrossRefGoogle Scholar
Martinez, G. D., Bullock, J. S., Kaplinghat, M., Strigari, L. E., & Trotta, R. 2009, JCAP, 06, 014CrossRefGoogle Scholar
Martinez, G. D., Minor, Q. E., Bullock, J., Kaplinghat, M., Simon, J. D., & Geha, M. 2010, arXiv1008.4585Google Scholar
McGaugh, S. S. & Wolf, J. 2010, arXiv1003.3448Google Scholar
Minor, Q. E, Martinez, G., Bullock, J., Kaplinghat, M., & Trainor, R. 2010, arXiv1001.1160Google Scholar
Navarro, J. F., Frenk, C. S., & White, S. D. M. 1997, ApJ, 490, 493CrossRefGoogle Scholar
Romanowsky, A. J., Douglas, N. G., Arnaboldi, M., Kuijken, K., Merrifield, M. R., Napolitano, N. R., Capaccioli, M., & Freeman, K. C. 2003, Science, 301, 1696CrossRefGoogle Scholar
Simon, J. D. et al. 2010, arXiv1007.4198Google Scholar
Strigari, L. E., Bullock, J. S., Kaplinghat, M., Diemand, J., Kuhlen, M., & Madau, P. 2007b, ApJ, 669, 676CrossRefGoogle Scholar
Strigari, L. E., Bullock, J. S., Kaplinghat, M., Simon, J. D., Geha, M., Willman, B., & Walker, M. G. 2008, Nature, 454, 1096CrossRefGoogle Scholar
Tollerud, E. J., Bullock, J. S., Graves, G. J., & Wolf, J. 2010, arXiv1007.5311Google Scholar
Wolf, J., Martinez, G. D., Bullock, J. S., Kaplinghat, M., Geha, M., Muñoz, R. R., Simon, J. D., & Avedo, F. F. 2010, MNRAS, 406, 1220Google Scholar