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Title: Dynamical Constraints on the Dark Matter Distribution of the Sculptor Dwarf Spheroidal from Stellar Proper Motions

Abstract

In this work, we compare the transverse velocity dispersions recently measured within the Sculptor dwarf spheroidal galaxy to the predictions of our previously published dynamical model. This was designed to fit the observed number count and velocity dispersion profiles of both metal-rich and metal-poor stars, both in cored and in cusped potentials. At the projected radius where the proper motions (PMs) were measured, this model (with no change in parameters) predicts transverse dispersions in the range of 6–9.5 km s -1, with the tangential dispersion about 1 km s -1 larger than the (projected) radial dispersion. Both dispersions are predicted to be about 1 km s -1 larger for metal-poor than for metal-rich stars. At this projected radius, cored and cusped potentials predict almost identical transverse dispersions. The measured tangential dispersion (8.5 ± 3.2 km s -1) agrees remarkably well with these predictions, while the measured radial dispersion (11.5 ± 4.3 km s -1) differs only at about the 1σ level. Thus, the PM data are in excellent agreement with previous data, but do not help to distinguish between cored and cusped potentials. Lastly, this will require velocity dispersion data (either from PMs or from radial velocities) with uncertainties wellmore » below 1 km s -1 over a range of projected radii.« less

Authors:
ORCiD logo [1];  [2];  [3]
  1. Texas A & M Univ., College Station, TX (United States)
  2. Univ. of Durham, Durham (United Kingdom)
  3. Max-Planck-Institut für Astrophysik, München (Germany)
Publication Date:
Research Org.:
Texas A & M Univ., College Station, TX (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1529519
Grant/Contract Number:  
SC0010813
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 860; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; dark matter; galaxies: dwarf; Local Group

Citation Formats

Strigari, Louis E., Frenk, Carlos S., and White, Simon D. M. Dynamical Constraints on the Dark Matter Distribution of the Sculptor Dwarf Spheroidal from Stellar Proper Motions. United States: N. p., 2018. Web. doi:10.3847/1538-4357/aac2d3.
Strigari, Louis E., Frenk, Carlos S., & White, Simon D. M. Dynamical Constraints on the Dark Matter Distribution of the Sculptor Dwarf Spheroidal from Stellar Proper Motions. United States. doi:10.3847/1538-4357/aac2d3.
Strigari, Louis E., Frenk, Carlos S., and White, Simon D. M. Tue . "Dynamical Constraints on the Dark Matter Distribution of the Sculptor Dwarf Spheroidal from Stellar Proper Motions". United States. doi:10.3847/1538-4357/aac2d3. https://www.osti.gov/servlets/purl/1529519.
@article{osti_1529519,
title = {Dynamical Constraints on the Dark Matter Distribution of the Sculptor Dwarf Spheroidal from Stellar Proper Motions},
author = {Strigari, Louis E. and Frenk, Carlos S. and White, Simon D. M.},
abstractNote = {In this work, we compare the transverse velocity dispersions recently measured within the Sculptor dwarf spheroidal galaxy to the predictions of our previously published dynamical model. This was designed to fit the observed number count and velocity dispersion profiles of both metal-rich and metal-poor stars, both in cored and in cusped potentials. At the projected radius where the proper motions (PMs) were measured, this model (with no change in parameters) predicts transverse dispersions in the range of 6–9.5 km s-1, with the tangential dispersion about 1 km s-1 larger than the (projected) radial dispersion. Both dispersions are predicted to be about 1 km s-1 larger for metal-poor than for metal-rich stars. At this projected radius, cored and cusped potentials predict almost identical transverse dispersions. The measured tangential dispersion (8.5 ± 3.2 km s-1) agrees remarkably well with these predictions, while the measured radial dispersion (11.5 ± 4.3 km s-1) differs only at about the 1σ level. Thus, the PM data are in excellent agreement with previous data, but do not help to distinguish between cored and cusped potentials. Lastly, this will require velocity dispersion data (either from PMs or from radial velocities) with uncertainties well below 1 km s-1 over a range of projected radii.},
doi = {10.3847/1538-4357/aac2d3},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 860,
place = {United States},
year = {2018},
month = {6}
}

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Cited by: 3 works
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