Galaxy chemical evolution models: The role of molecular gas formation

Abstract

In our grid of multiphase chemical evolution models (Mollá & Díaz, 2005), star formation in the disk occurs in two steps: first, molecular gas forms, and then stars are created by cloud-cloud collisions or interactions of massive stars with the surrounding molecular clouds. The formation of both molecular clouds and stars are treated through the use of free parameters we refer to as efficiencies. In this work we modify the formation of molecular clouds based on several new prescriptions existing in the literature, and we compare the results obtained for a chemical evolution model of the Milky Way Galaxy regarding the evolution of the Solar region, the radial structure of the Galactic disk, and the ratio between the diffuse and molecular components, HI/H${}_2$. Our results show that the six prescriptions we have tested reproduce fairly consistent most of the observed trends, differing mostly in their predictions for the (poorly-constrained) outskirts of the Milky Way and the evolution in time of its radial structure. Among them, the model proposed by Ascasibar et al. (2017), where the conversion of diffuse gas into molecular clouds depends on the local stellar and gas densities as well as on the gas metallicity, seems to provide the best overall match to the observed data.

14 pages, 13 figures, accepted by Monthly Notices of the Royal Astronomical Society

References in corpus (17)

• The Role of Pressure in GMC Formation II: The H_2 - Pressure Relation
• Cold gas accretion in galaxies
• The Atomic to Molecular Transition in Galaxies. II: HI and H_2 Column Densities
• Size evolution of the most massive galaxies at 1.7<z<3 from GOODS NICMOS survey imaging
• The Universal Rotation Curve of Spiral Galaxies. II The Dark Matter Distribution out to the Virial Radius
• Environmental Dependence of the Kennicutt-Schmidt Relation in Galaxies
• The Atomic to Molecular Transition in Galaxies. I: An Analytic Approximation for Photodissociation Fronts in Finite Clouds
• Shape of the oxygen abundance profiles in CALIFA face-on spiral galaxies
• Star formation at very low metallicity. I: Chemistry and cooling at low densities
• Evolution of the Milky Way with radial motions of stars and gas I. The solar neighborhood and the thin and thick disk
• The Atomic to Molecular Transition and its Relation to the Scaling Properties of Galaxy Disks in the Local Universe
• Chemical Rates on Small Grains and PAHs: C^+ Recombination and H_2 Formation
• Evolution of the Milky Way with radial motions of stars and gas II. The evolution of abundance profiles from H to Ni
• Understanding chemical evolution in resolved galaxies -- I The local star fraction-metallicity relation
• The role of gas infall in the evolution of disc galaxies
• Chemical and photometric evolution models for disk, irregular and low mass galaxies
• Comment on "The Cosmic Time in Terms of the Redshift", by Carmeli et al

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• On the origin of the mass-metallicity gradient relation in the local Universe
• The time evolution of the Milky Way's oxygen abundance gradient
• 2D-Galactic chemical evolution: the role of the spiral density wave
• Recent star formation episodes in the Galaxy: impact on its chemical properties and the evolution of its abundance gradient
• Chemical evolution of galaxies: emerging dust and the different gas phases in a new multiphase code
• Inner and outer star forming regions over the disks of spiral galaxies. II. A comparative of physical properties and evolutionary stages
• Predicting interstellar radiation fields from chemical evolution models
• Local metallicity distribution function derived from Galactic large-scale radial iron pattern modelling