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arXiv · 0907.0260

A Test of Star Formation Laws in Disk Galaxies

Jonathan C. Tan
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Abstract

We use observations of the radial profiles of the mass surface density of total, Sigma_g, and molecular, Sigma_H2, gas, rotation velocity and star formation rate surface density, Sigma_sfr, of the molecular dominated regions of 12 disk galaxies from Leroy et al. to test several star formation laws: a "Kennicutt-Schmidt power law", Sigma_sfr=A_g Sigma_{g,2}^{1.5}$; a "Constant molecular law", Sigma_sfr = A_H2 Sigma_{H2,2}; the "Turbulence-regulated laws" of Krumholz & McKee (KM) and Krumholz, McKee & Tumlinson (KMT), a "Gas-Omega law", Sigma_sfr = B_Omega Sigma_g Omega; and a shear-driven "GMC collisions law", Sigma_sfr = B_CC Sigma_g Omega (1 - 0.7beta), where beta is d ln v_circ / d ln r. We find the constant molecular law, KMT turbulence law and GMC collision law are the most accurate, with an rms error of a factor of 1.5 if the normalization constants are allowed to vary between galaxies. Of these three laws, the GMC collision law does not require a change in physics to account for the full range of star formation activity seen from normal galaxies to circumnuclear starbursts. A single global GMC collision law with B_CC=8.0x10^{-3}, i.e. a gas consumption time of 20 orbital times for beta=0, yields an rms error of a factor of 1.8.

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Jonathan C. Tan. 2010-07-08. A Test of Star Formation Laws in Disk Galaxies. https://doi.org/10.1088/2041-8205%2F710%2F1%2Fl88

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