HI scale height in dwarf galaxies. (arXiv:2005.05979v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Patra_N/0/1/0/all/0/1">Narendra Nath Patra</a>
Assuming a vertical hydrostatic equilibrium in the baryonic discs, joint
Poisson’s-Boltzmann equation was set up and solved numerically in a sample of
23 nearby dwarf galaxies from the LITTLE-THINGS survey. This is the largest
sample to date for which detailed hydrostatic modeling is performed. The
solutions of the Poisson’s-Boltzmann equation provide a complete
three-dimensional distribution of the atomic hydrogen (HI) in these galaxies.
Using these solutions, we estimate the vertical scale height (defined as the
Half Width at Half Maxima (HWHM) of the density distribution) of the HI as a
function of radius. We find that the scale height in our sample galaxies varies
between a few hundred parsecs at the center to a few kiloparsecs at the edge.
These values are significantly higher than what is observed in spiral galaxies.
We further estimate the axial ratios to investigate the thickness of the HI
discs in dwarf galaxies. For our sample galaxies, we find a median axial ratio
to be 0.40, which is much higher than the same observed in the Milky Way. This
indicates that the vertical hydrostatic equilibrium results in thicker HI discs
in dwarf galaxies naturally.
Assuming a vertical hydrostatic equilibrium in the baryonic discs, joint
Poisson’s-Boltzmann equation was set up and solved numerically in a sample of
23 nearby dwarf galaxies from the LITTLE-THINGS survey. This is the largest
sample to date for which detailed hydrostatic modeling is performed. The
solutions of the Poisson’s-Boltzmann equation provide a complete
three-dimensional distribution of the atomic hydrogen (HI) in these galaxies.
Using these solutions, we estimate the vertical scale height (defined as the
Half Width at Half Maxima (HWHM) of the density distribution) of the HI as a
function of radius. We find that the scale height in our sample galaxies varies
between a few hundred parsecs at the center to a few kiloparsecs at the edge.
These values are significantly higher than what is observed in spiral galaxies.
We further estimate the axial ratios to investigate the thickness of the HI
discs in dwarf galaxies. For our sample galaxies, we find a median axial ratio
to be 0.40, which is much higher than the same observed in the Milky Way. This
indicates that the vertical hydrostatic equilibrium results in thicker HI discs
in dwarf galaxies naturally.
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