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2011MNRAS.411.2118A - Mon. Not. R. Astron. Soc., 411, 2118-2136 (2011/March-2)
Phase-space models of the dwarf spheroidals.
AMORISCO N.C. and EVANS N.W.
Abstract (from CDS):
The origin of the observational correlation between half-light radius Rh and line-of-sight central velocity dispersion σ_p, 0_ is investigated. We prove that a power-law correlation Rh∝σDp,0 can exist if, and only if, the dark halo potential is a power law of the radius. Although a power law is a good approximation in the central parts (D= 2 for a Navarro-Frenk-White halo, D= 1 for cored haloes), the theoretical correlation curve between Rh and σ_p, 0_ dramatically steepens at larger half-light radii. Using our phase-space models, we show that different dark halo profiles - whether cored or cusped - lead to very similar mass estimates within one particular radius, ≈1.7Rh. The formula for the enclosed mass M(<1.7Rh) is ≈5.8 σ2p,0Rh/G and extends out to larger radii than those in previous investigations. This is a tight result for models with a flattish projected velocity dispersion profile (out to several half-light radii). We show that deviations between mass measures due to different density profiles are substantially smaller than the uncertainties propagated by the observational errors on the half-light radius and central velocity dispersion. We produce a mass measure for each of the dSphs and find that the two most massive of the Milky Way dSphs are the most luminous, namely Sgr (M(<1.7Rh) ∼ 2.8 {x} 108 M☉) and Fornax (∼1.3 {x} 108 M☉). The least massive of the Milky Way satellites are Willman 1 (∼4 {x} 105 M☉) and Segue 1 (∼6 {x} 105 M☉).
Abstract Copyright: 2010 The Authors Monthly Notices of the Royal Astronomical Society2010 RAS
Journal keyword(s): galaxies: dwarf - galaxies: kinematics and dynamics - Local Group
Simbad objects: 33
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