Dwarf spheroidals in MOND

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Abstract

We take the line-of-sight velocity dispersions as functions of radius for eight Milky Way dwarf spheroidal galaxies and use Jeans analysis to calculate the mass-to-light ratios (M/L) in Modified Newtonian Dynamics (MOND). Using the latest structural parameters, distances and variable velocity anisotropy, we find six out of eight dwarfs have sensible M/L using only the stellar populations. Sextans and Draco, however, have M/L = 9.2 +5.3 -3.0 and 43.9 +29.0 -19.3 respectively, which poses a problem. Apart from the need for Sextans' integrated magnitude to be reviewed, we propose tidal effects intrinsic to MOND, testable with numerical simulations, but fully orbit dependant, which are disrupting Draco. The creation of the Magellanic Stream is also re-addressed in MOND, the scenario being the stream is ram pressure stripped from the SMC as it crosses the LMC.

Original languageEnglish
Pages (from-to)1481-1488
Number of pages8
JournalMonthly Notices of the Royal Astronomical Society
Volume387
Issue number4
DOIs
Publication statusPublished - Jul 2008

All Science Journal Classification (ASJC) codes

  • Space and Planetary Science
  • Astronomy and Astrophysics

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