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 Astrofisico 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, Extragalactic Astrophysics

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 56

Subject Categories

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

DOI

10.3847/1538-4357/aacffa

More information

Latest update

8/29/2018