mgwalker@umich.edu dsph masses matthew walker – ioa, cambridge with mario mateo - u. michigan...

mgwalker@umich.edu

dSph Masses

Matthew Walker – IoA, Cambridge

withMario Mateo - U. MichiganEdward Olszewski - U. ArizonaJorge Peñarrubia - IoAWyn Evans - IoAGerry Gilmore - IoA

--Stay tuned for Joe Wolf’s talk too--

Extreme Star Formation in Dwarf Galaxies

Ann Arbor, 28 July, 2009

mgwalker@umich.edu

Velocity Dispersion Profiles

Walker etal (arXiv:0906.0341)

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Kinematics with the Jeans Equation

1) Jeans Eq. (spherical)

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3) Adopt Hernquist Halo Model

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Free Parameters V_max, r_scale, alpha, gamma, beta=constant

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2) Solution in terms of observables

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Fornax: Vmax = 20 +/- 4 km/s

arXiv:0906.0341

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M(rhalf) for 8 “classical” dSphs

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arXiv:0906.0341

• Robust to large ranges for r0, alpha, gamma, beta

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Simple Mass Estimator

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QuickTime™ and aTIFF (Uncompressed) decompressor

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Isotropy, flat vdisp profile -->

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Simple Mass Estimator

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Simple Mass Estimator

c.f. Strigari et al. 2008

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Data for 28 Satellites

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arXiv:0906.0341

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A Universal Mass Profile?

arXiv:0906.0341

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Velocity Dispersion vs. Size

arXiv:0906.0341

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Universal Mass Profile?

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arXiv:0906.0341

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Scatter wrt Universal Profile and M300

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arXiv:0906.0341

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