2017/10/31 by Stacy McGaugh, Jim Schombert, Federico Lelli · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/aa9790
published as 2017, ApJ, 851, 22 · Accepted for publication in the Astrophysical Journal. 11 pages, 3 figures. Second version identical to original version; fixed one typo in metadata abstract
arxiv created 2017/11/01 · arxiv updated 2017/12/11
We explore the star forming properties of late type, low surface brightness (LSB) galaxies. The star forming main sequence (SFR-M_*) of LSB dwarfs has a steep slope, indistinguishable from unity (1.04 ± 0.06). They form a distinct sequence from more massive spirals, which exhibit a shallower slope. The break occurs around M_* ≈ 1010 M\odot, and can also be seen in the gas mass-stellar mass plane. The global Kennicutt-Schmidt law (SFR-Mg) has a slope of 1.47 ± 0.11 without the break seen in the main sequence. There is an ample supply of gas in LSB galaxies, which have gas depletion times well in excess of a Hubble time, and often tens of Hubble times. Only ∼ 3% of this cold gas need be in the form of molecular gas to sustain the observed star formation. In analogy with the faint, long-lived stars of the lower stellar main sequence, it may be appropriate to consider the main sequence of star forming galaxies to be defined by thriving dwarfs (with M_* < 1010 M\odot) while massive spirals (with M_* > 1010 M\odot) are weary giants that constitute more of a turn-off population.