VALES VII: Molecular and ionized gas properties in pressure balanced interstellar medium of starburst galaxies at z ~ 0.15

Juan Molina; Edo Ibar; Nicolas Godoy; Andres Escala; Tomonari Michiyama; Cheng Cheng; Thomas M. Hughes; Maarten Baes; Yongquan Xue; Michał J. Michałowski; Paul van der Werf; Xue-Jian Jiang

doi:10.1051/0004-6361/202039008

paper

VALES VII: Molecular and ionized gas properties in pressure balanced interstellar medium of starburst galaxies at z ~ 0.15

arXiv:2009.08446 · doi:10.1051/0004-6361/202039008

Abstract

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 $\sim$ 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-H $_{2}$ 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 $\sim 0.1 - 1$ Gyr. The star formation rate surface density ( $Σ_{SFR}$ ) correlates with the ISM pressure set by self-gravity ( $P_{grav}$ ) 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 $Σ_{SFR}$ and $P_{grav}$ suggests that, in these dusty starbursts galaxies, the star formation activity arises as a consequence of the ISM pressure balance.

Accepted for publication in A&A; 18 pages, 9 figures, 5 tables plus appendix. Figure 3 may not be correctly visualized in web browser

VALES VII: Molecular and ionized gas properties in pressure balanced interstellar medium of starburst galaxies at z ~ 0.15

Abstract

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