The Star Forming Main Sequence of Dwarf Low Surface Brightness Galaxies

Stacy McGaugh; Jim Schombert; Federico Lelli

doi:10.3847/1538-4357/aa9790

paper

The Star Forming Main Sequence of Dwarf Low Surface Brightness Galaxies

arXiv:1710.11236 · doi:10.3847/1538-4357/aa9790

Abstract

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 ( $1.04 \pm 0.06$ ). They form a distinct sequence from more massive spirals, which exhibit a shallower slope. The break occurs around $M_{*} \approx 1 0^{10} M_{⊙}$ , and can also be seen in the gas mass-stellar mass plane. The global Kennicutt-Schmidt law (SFR- $M_{g}$ ) has a slope of $1.47 \pm 0.11$ 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 $\sim 3%$ 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 $M_{*} < 1 0^{10} M_{⊙}$ ) while massive spirals (with $M_{*} > 1 0^{10} M_{⊙}$ ) are weary giants that constitute more of a turn-off population.

Accepted for publication in the Astrophysical Journal. 11 pages, 3 figures. Second version identical to original version; fixed one typo in metadata abstract

The Star Forming Main Sequence of Dwarf Low Surface Brightness Galaxies

Abstract

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