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arXiv · 1605.01489

New Lessons from the HI Size-Mass Relation of Galaxies

Jing Wang·Bärbel S. Koribalski·Paolo Serra·Thijs van der Hulst·Sambit Roychowdhury·Peter Kamphuis·Jayaram N. Chengalur
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Abstract

We revisit the HI size-mass (D$_{\rm HI}$-M$_{\rm HI}$) relation of galaxies with a sample of more than 500 nearby galaxies covering over five orders of magnitude in HI mass and more than ten $B$-band magnitudes. The relation is remarkably tight with a scatter $σ\sim$0.06 dex, or 14%. The scatter does not change as a function of galaxy luminosity, HI richness or morphological type. The relation is linked to the fact that dwarf and spiral galaxies have a homogenous radial profile of HI surface density in the outer regions when the radius is normalised by D$_{\rm HI}$. The early-type disk galaxies typically have shallower HI radial profiles, indicating a different gas accretion history. We argue that the process of atomic-to-molecular gas conversion or star formation cannot explain the tightness of the D$_{\rm HI}$-M$_{\rm HI}$ relation. This simple relation puts strong constraints on simulation models for galaxy formation.

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Jing Wang, Bärbel S. Koribalski, Paolo Serra, Thijs van der Hulst, Sambit Roychowdhury, Peter Kamphuis, Jayaram N. Chengalur. 2016-05-05. New Lessons from the HI Size-Mass Relation of Galaxies. https://doi.org/10.1093/mnras%2Fstw1099

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