INTERNAL DYNAMICS AND DYNAMICAL FRICTION EFFECTS IN THE DWARF SPHEROIDAL GALAXY IN FORNAX

Cowsik, Ramanath; Wagoner, Kasey; Sircar, Amit; Berti, Emanuele

doi:10.1088/0004-637X/699/2/1389; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)

Title: INTERNAL DYNAMICS AND DYNAMICAL FRICTION EFFECTS IN THE DWARF SPHEROIDAL GALAXY IN FORNAX

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Abstract

In the Fornax dwarf spheroidal galaxy the globular clusters are distributed widely, without any significant central concentration. Oh et al. pointed out that such a distribution is paradoxical: dynamical friction effects estimated using single-component King models would have forced the globular clusters to spiral down to the center of the galaxy well within a Hubble time. This paper is devoted to a discussion of this paradox. We describe a model in which the stars of the dwarf spheroidal galaxy are embedded in a cloud of dark matter, and each of these components is specified by its own phase-space distribution function. This model allows us to fit self-consistently the observed luminosity profile and the spatial variation of the velocity dispersion of the stars. This fitting yields two basic parameters, related to the central density and velocity dispersion, that characterize the phase-space distribution of dark matter. The dynamical friction effects calculated on the basis of this self-consistent model are small enough that the observed spatial distribution of the globular clusters poses no difficulty, and the apparent paradox is resolved. Thus, we have at hand a model for Fornax that reproduces the main observed features of this dwarf spheroidal galaxy.

Authors:

Cowsik, Ramanath; Wagoner, Kasey; Sircar, Amit ^[1]; Berti, Emanuele ^[2]

McDonnell Center for the Space Sciences, Department of Physics, Washington University, St. Louis, MO 63130 (United States)
Department of Physics and Astronomy, University of Mississippi, University, MS 38677-1848 (United States)

Publication Date:: Fri Jul 10 00:00:00 EDT 2009

OSTI Identifier:: 21333733

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 699; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/699/2/1389; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DISTRIBUTION FUNCTIONS; FRICTION; GALAXIES; LUMINOSITY; NONLUMINOUS MATTER; PHASE SPACE; SPATIAL DISTRIBUTION; STARS

Citation Formats


                    Cowsik, Ramanath, Wagoner, Kasey, Sircar, Amit, and Berti, Emanuele. INTERNAL DYNAMICS AND DYNAMICAL FRICTION EFFECTS IN THE DWARF SPHEROIDAL GALAXY IN FORNAX.  United States: N. p., 2009. 
        Web.  doi:10.1088/0004-637X/699/2/1389; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).

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                    Cowsik, Ramanath, Wagoner, Kasey, Sircar, Amit, & Berti, Emanuele. INTERNAL DYNAMICS AND DYNAMICAL FRICTION EFFECTS IN THE DWARF SPHEROIDAL GALAXY IN FORNAX.  United States.  https://doi.org/10.1088/0004-637X/699/2/1389; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)

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                    Cowsik, Ramanath, Wagoner, Kasey, Sircar, Amit, and Berti, Emanuele. 2009.  
        "INTERNAL DYNAMICS AND DYNAMICAL FRICTION EFFECTS IN THE DWARF SPHEROIDAL GALAXY IN FORNAX".  United States.  https://doi.org/10.1088/0004-637X/699/2/1389; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).

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@article{osti_21333733,

  title        = {INTERNAL DYNAMICS AND DYNAMICAL FRICTION EFFECTS IN THE DWARF SPHEROIDAL GALAXY IN FORNAX},

  author       = {Cowsik, Ramanath and Wagoner, Kasey and Sircar, Amit and Berti, Emanuele},

  abstractNote = {In the Fornax dwarf spheroidal galaxy the globular clusters are distributed widely, without any significant central concentration. Oh et al. pointed out that such a distribution is paradoxical: dynamical friction effects estimated using single-component King models would have forced the globular clusters to spiral down to the center of the galaxy well within a Hubble time. This paper is devoted to a discussion of this paradox. We describe a model in which the stars of the dwarf spheroidal galaxy are embedded in a cloud of dark matter, and each of these components is specified by its own phase-space distribution function. This model allows us to fit self-consistently the observed luminosity profile and the spatial variation of the velocity dispersion of the stars. This fitting yields two basic parameters, related to the central density and velocity dispersion, that characterize the phase-space distribution of dark matter. The dynamical friction effects calculated on the basis of this self-consistent model are small enough that the observed spatial distribution of the globular clusters poses no difficulty, and the apparent paradox is resolved. Thus, we have at hand a model for Fornax that reproduces the main observed features of this dwarf spheroidal galaxy.},

  doi          = {10.1088/0004-637X/699/2/1389; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},

  url          = {https://www.osti.gov/biblio/21333733},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 2,

  volume       = 699,

  place        = {United States},

  year         = {Fri Jul 10 00:00:00 EDT 2009},

  month        = {Fri Jul 10 00:00:00 EDT 2009}

}

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https://doi.org/10.1088/0004-637X/699/2/1389; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)

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