Resolving the ISM at the Peak of Cosmic Star Formation with ALMA: The Distribution of CO and Dust Continuum in z ∼2.5 Submillimeter Galaxies
Journal article, 2018
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 (0.″1-0.″6). The velocity fields of our sources, traced by the12CO(J =3-2) emission, are consistent with disk rotation to the first order, implying average dynamical masses of ∼3 1011within 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-H2conversion factor, αCO, 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).
ISM: structure
submillimeter: galaxies
galaxies: ISM
galaxies: structure
galaxies: kinematics and dynamics
submillimeter: ISM
Author
Gabriela Calistro Rivera
Leiden University
J. Hodge
Leiden University
I. Smail
Durham University
A.M. Swinbank
Durham University
A. Weiß
Max Planck Society
J. L. Wardlow
Durham University
F. Walter
Max Planck Society
M. Rybak
Leiden University
C. C. Chen
European Southern Observatory (ESO)
W. N. Brandt
Pennsylvania State University
K. E. K. Coppin
University of Hertfordshire
E. Da Cunha
Australian National University
H. Dannerbauer
Instituto de Astrofísica de Canarias
University of La Laguna
T. R. Greve
University College London (UCL)
A. Karim
University of Bonn
Kirsten Kraiberg Knudsen
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
E. Schinnerer
Max Planck Society
J. M. Simpson
Academia Sinica
B. Venemans
Max Planck Society
P. van der Werf
Leiden University
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 863 1 56Subject Categories
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
Atom and Molecular Physics and Optics
DOI
10.3847/1538-4357/aacffa