On the Functional Form of the Universal Star-formation Law
Abstract
We study the functional form of the star-formation law using the Vaschy-Buckingham Pi theorem. We find that it should have the form {{\dot{ Σ }}\star }\propto \sqrt{\frac{G}{L}}{Σ }gas3/2, where L is a characteristic length that is related to an integration scale. With a reasonable estimate for L, we find that galaxies of different types and redshifts, including low-surface-brightness galaxies and individual star-forming regions in our Galaxy, obey this single star-formation law. We also find that, depending on the assumption for L, this star-formation law adopts different formulations of {{\dot{ Σ }}\star } scaling that are widely studied in the literature: {Σ }gas3/2,{{{Σ }}gas}/{{t}orb},{{{Σ }}gas}/{{t}ff} and {Σ }gas2/{{v}turb}. We also study secondary controlling parameters of the star-formation law based on the current evidence from numerical simulations, and we find that for galaxies the star-formation efficiency should be controlled, at least, by the turbulent Toomre parameter and the sonic and Alfvénic Mach numbers.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 2015
- DOI:
- 10.1088/0004-637X/804/1/54
- arXiv:
- arXiv:1411.7043
- Bibcode:
- 2015ApJ...804...54E
- Keywords:
-
- galaxies: formation;
- stars: formation;
- stars: general;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted version after referee report. 20 pages, 4 figures