2019/09/03 by Yanxia Xie, Luis C. Ho · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/ab4200
16 pages, 5 figures, 2 tables, accepted for publication in ApJ
arxiv created 2019/09/03 · arxiv updated 2019/11/06
Polycyclic aromatic hydrocarbon (PAH) emission has long been proposed to be a potential star formation rate indicator, as it arises from the photodissociation region bordering the Strömgren sphere of young, massive stars. We apply a recently developed technique of mid-infrared spectral decomposition to obtain a uniform set of PAH measurements from Spitzer low-resolution spectra of a large sample of star-forming galaxies spanning a wide range in stellar mass (M_⋆ ≈ 106-1011.4 M\odot) and star formation rate (∼ 0.1- 2000 M\odot\rm yr-1). High-resolution spectra are also analyzed to measure [Ne II] 12.8 μm and [Ne III] 15.6 μm, which effectively trace the Lyman continuum. We present a new relation between PAH luminosity and star formation rate based on the [Ne II] and [Ne III] lines. Calibrations are given for the integrated 5-15 μm PAH emission, the individual features at 6.2, 7.7, 8.6, and 11.3 μm, as well as several mid-infrared bandpasses sensitive to PAH. We confirm that PAH emission is suppressed in low-mass, dwarf galaxies, and we discuss the possible physical origin of this effect.