2020/09/17 by Juan Molina, Edo Ibar, Nicolas Godoy +9 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/202039008
published as A&A 643, A78 (2020) · Accepted for publication in A&A; 18 pages, 9 figures, 5 tables plus appendix. Figure 3 may not be correctly visualized in web browser
arxiv created 2020/09/17 · arxiv updated 2020/11/11
Context. Spatially resolved observations of the ionized and molecular gas are critical for understanding the physical processes that govern the interstellar medium (ISM) in galaxies. Aims. To study the morpho-kinematic properties of the ionized and molecular gas in three dusty starburst galaxies at z = 0.12-0.17 to explore the relation between molecular ISM gas phase dynamics and the star-formation activity. Methods. We analyse ∼kpc-scale ALMA CO(1--0) and seeing limited SINFONI Paschen-α observations. We use a dynamical mass model, which accounts for beam-smearing effects, to constrain the CO-to-H2 conversion factor. Results. One starburst galaxy shows irregular morphology which may indicate a major merger, while the other two systems show disc-like morpho-kinematics. The two disc-like starbursts show molecular gas velocity dispersion values comparable with that seen in local LIRG/ULIRGs, but in an ISM with molecular gas fraction and surface density values consistent to that reported for local star-forming galaxies. These molecular gas velocity dispersion values can be explained by assuming vertical pressure equilibrium. The star-formation activity is correlated with the molecular gas content suggesting depletion times of the order of ∼ 0.1-1 Gyr. The star formation rate surface density (Σ\rm SFR) correlates with the ISM pressure set by self-gravity (P\rm grav) following a power law with an exponent close to 0.8. Conclusions. In dusty disc-like starburst galaxies, our data support the scenario in which the molecular gas velocity dispersion values are driven by the ISM pressure set by self-gravity, responsible to maintain the vertical pressure balance. The correlation between Σ\rm SFR and P\rm grav suggests that, in these dusty starbursts galaxies, the star formation activity arises as a consequence of the ISM pressure balance.