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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:
Journal Article: Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
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. https://doi.org/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. https://doi.org/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},
url = {https://www.osti.gov/biblio/1529519}, journal = {The Astrophysical Journal (Online)},
issn = {1538-4357},
number = 1,
volume = 860,
place = {United States},
year = {2018},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 7 works
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Web of Science

Figures / Tables:

Figure 1 Figure 1: Posterior probability densities for the transverse radial and tangential velocity dispersions for different populations, based on the models of Strigari et al. (2017) which fit parameterized distribution functions to star count and LOS velocity dispersion data from Walker & Penarrubia (2011). The top row assumes an NFW darkmore » matter profile and the bottom row a Burkert profile. The red histogram is for the MR population, the blue histogram is for the MP population, and the black histogram for the total population. The thin black curves are Gaussian distributions that represent the PM-based estimates of Massari et al. (2017) and their 1σ uncertainty.« less

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Works referenced in this record:

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    Works referencing / citing this record:

    Stellar chemo-kinematics of the Cetus dwarf spheroidal galaxy
    journal, October 2018


    The effect of tides on the Sculptor dwarf spheroidal galaxy
    journal, May 2019


    Stellar chemo-kinematics of the Cetus dwarf spheroidal galaxy
    journal, October 2018


    The effect of tides on the Sculptor dwarf spheroidal galaxy
    journal, May 2019


    Towards an improved model of self-interacting dark matter haloes
    journal, December 2018


    Dark matter heats up in dwarf galaxies
    journal, January 2019


    Scale-invariant dynamics of galaxies, MOND, dark matter, and the dwarf spheroidals
    journal, December 2019


      Figures / Tables found in this record:

        Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.