Estimating Dark Matter Distributions

Details Estimating Dark Matter Distributions Estimating Dark Matter Distributions

2005-04-11

arxiv.org/abs/astro-ph/0504239v1

Astrophys.J. 626 (2005) 145-158

Astronomy and Astrophysics

Astrophysics

Accepted for publication in The Astrophysical Journal

Scientific paper

10.1086/429792

Thanks to instrumental advances, new, very large kinematic datasets for nearby dwarf spheroidal (dSph) galaxies are on the horizon. A key aim of these datasets is to help determine the distribution of dark matter in these galaxies. Past analyses have generally relied on specific dynamical models or highly restrictive dynamical assumptions. We describe a new, non-parametric analysis of the kinematics of nearby dSph galaxies designed to take full advantage of the future large datasets. The method takes as input the projected positions and radial velocities of stars known to be members of the galaxies, but does not use any parametric dynamical model, nor the assumption that the mass distribution follows that of the visible matter. The problem of estimating the radial mass distribution, M(r) (the mass interior to true radius r), is converted into a problem of estimating a regression function non-parametrically. From the Jeans Equation we show that the unknown regression function is subject to fundamental shape restrictions which we exploit in our analysis using statistical techniques borrowed from isotonic estimation and spline smoothing. Simulations indicate that M(r) can be estimated to within a factor of two or better with samples as small as 1000 stars over almost the entire radial range sampled by the kinematic data. The technique is applied to a sample of 181 stars in the Fornax dSph galaxy. We show that the galaxy contains a significant, extended dark halo some ten times more massive than its baryonic component. Though applied here to dSph kinematics, this approach can be used in the analysis of any kinematically hot stellar system in which the radial velocity field is discretely sampled.

Affiliated with

Also associated with

No associations

Rating

Estimating Dark Matter Distributions does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Estimating Dark Matter Distributions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Estimating Dark Matter Distributions will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-21576