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Commonly used dwarf galaxy mass estimators are accurate, even for non-spherical galaxies. The half-light radius (Re) is key to accurate mass estimation, with analytic fits outperforming direct summation.

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Area of Science:

  • Cosmology
  • Astrophysics
  • Galaxy Formation and Evolution

Background:

  • Dwarf galaxies are crucial for understanding galaxy formation.
  • Accurate mass estimation is vital for studying dwarf galaxy properties.
  • Existing mass estimators rely on velocity dispersion and half-light radius (Re).

Purpose of the Study:

  • To test the accuracy of widely used dwarf galaxy mass estimators.
  • To evaluate estimator performance in realistic, non-spherical galaxy simulations.
  • To identify key factors influencing mass estimation accuracy.

Main Methods:

  • Utilized high-resolution cosmological simulations from the FIRE (Feedback In Realistic Environments) project.
  • Simulated 12 dwarf galaxy systems with stellar masses from 10^5 to 10^7 M☉.
  • Compared results from Walker et al. (2009) and Wolf et al. (2010) mass estimators.

Main Results:

  • Both mass estimators demonstrated high accuracy, with errors within the 68% range.
  • Estimator accuracy remained high despite significant deviations from spherical symmetry in simulated galaxies.
  • The accuracy of mass estimators showed no correlation with galaxy asphericity.
  • Determining Re via analytic fits to surface density profiles yielded more accurate mass estimates than direct summation.

Conclusions:

  • Commonly used mass estimators are robust and accurate for dwarf galaxies, even those with non-spherical shapes.
  • The half-light radius (Re) is the most critical observational parameter for accurate mass estimation.
  • Analytic fitting of surface density profiles is recommended for determining Re to improve mass estimation.