Dynamical Properties of Molecular-forming Gas Clumps in Galaxies at the Epoch of Reionization

We study the properties of molecular-forming gas clumps (MGCs) at the epoch of reionization using cosmological zoom-in simulations. We identify MGCs in a z=6 prototypical galaxy ("Althaea") using an H2 density-based clump finder. We compare their mass, size, velocity dispersion, gas surfac...

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Bibliographic Details
Published in:arXiv.org 2020-04
Main Authors: Leung, T K Daisy, Pallottini, Andrea, Ferrara, Andrea, Mordecai-Mark Mac Low
Format: Article
Language:English
Subjects:
Arrays
Clumps
Density
Dynamic stability
Gas dynamics
Ionization
Molecular clouds
Properties (attributes)
Q values
Spatial resolution
Spirals
Stability analysis
Star & galaxy formation
Star formation
Starburst galaxies
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Summary:We study the properties of molecular-forming gas clumps (MGCs) at the epoch of reionization using cosmological zoom-in simulations. We identify MGCs in a z=6 prototypical galaxy ("Althaea") using an H2 density-based clump finder. We compare their mass, size, velocity dispersion, gas surface density, and virial parameter (alpha_vir) to observations. In Althaea, the typical MGC mass and size are Mgas=10^6.5 Msun and R=45-100 pc, which are comparable to those found in nearby spirals and starburst galaxies. MGCs are highly supersonic and supported by turbulence, with rms velocity dispersions of sigma_gas=20-100 km s^-1 and pressure of P/k_B=10^7.6 K cm^-3 (i.e., >1000x with respect to the Milky Way), similar to those found in nearby and z~2 gas-rich starburst galaxies. In addition, we perform stability analysis to understand the origin and dynamical properties of MGCs. We find that MGCs are globally stable in the main disk of Althaea. Densest regions where star formation is expected to take place in clouds and cores on even smaller scales instead have lower alpha_vir and Toomre-Q values. Detailed studies of the star-forming gas dynamics at the epoch of reionization thus require a spatial resolution of
ISSN:2331-8422
DOI:10.48550/arxiv.1907.02972