A New Calibration of Star Formation Rate in Galaxies Based on Polycyclic Aromatic Hydrocarbon Emission

Yanxia Xie; Luis C. Ho

doi:10.3847/1538-4357/ab4200

paper

A New Calibration of Star Formation Rate in Galaxies Based on Polycyclic Aromatic Hydrocarbon Emission

arXiv:1909.01110 · doi:10.3847/1538-4357/ab4200

Abstract

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 ( $M_{⋆} \approx 1 0^{6} - 1 0^{11.4} M_{⊙}$ ) and star formation rate ( $\sim 0.1 - 2000 M_{⊙} y r^{- 1}$ ). High-resolution spectra are also analyzed to measure [Ne II] 12.8 $μ$ m and [Ne III] 15.6 $μ$ m, 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 $5 - 15$ $μ$ m PAH emission, the individual features at 6.2, 7.7, 8.6, and 11.3 $μ$ m, 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.

arXiv comment16 pages, 5 figures, 2 tables, accepted for publication in ApJ

A New Calibration of Star Formation Rate in Galaxies Based on Polycyclic Aromatic Hydrocarbon Emission

Abstract

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