Abstract
We use Atacama Large Millimeter Array (ALMA) observations of four submillimeter galaxies (SMGs) at z ~ 2–3 to investigate the spatially resolved properties of the interstellar medium (ISM) at scales of 1–5 kpc (01–06). The velocity fields of our sources, traced by the 12CO(J = 3–2) emission, are consistent with disk rotation to the first order, implying average dynamical masses of ~3 × 1011 within
two half-light radii. Through a Bayesian approach we investigate the
uncertainties inherent to dynamically constraining total gas masses. We
explore the covariance between the stellar mass-to-light ratio and
CO-to-H2 conversion factor, α CO, finding values of
for dark matter fractions of 15%. We show that the resolved spatial
distribution of the gas and dust continuum can be uncorrelated to the
stellar emission, challenging energy balance assumptions in global SED
fitting. Through a stacking analysis of the resolved radial profiles of
the CO(3–2), stellar, and dust continuum emission in SMG samples, we
find that the cool molecular gas emission in these sources (radii ~5–14
kpc) is clearly more extended than the rest-frame ~250 μm dust
continuum by a factor >2. We propose that assuming a constant
dust-to-gas ratio, this apparent difference in sizes can be explained by
temperature and optical depth gradients alone. Our results suggest that
caution must be exercised when extrapolating morphological properties
of dust continuum observations to conclusions about the molecular gas
phase of the interstellar medium (ISM).
Original language | English |
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Article number | 56 |
Number of pages | 16 |
Journal | The Astrophysical Journal |
Volume | 863 |
Issue number | 1 |
Early online date | 9 Aug 2018 |
DOIs | |
Publication status | Published - 10 Aug 2018 |
Keywords
- astro-ph.GA