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arXiv · 1504.02142

ALMA observations of 99 GHz free-free and H40$\alpha$ line emission from star formation in the centre of NGC 253

G. J. Bendo·R. J. Beswick·M. J. D'Cruze·C. Dickinson·G. A. Fuller·T. W. B. Muxlow
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Abstract

We present Atacama Large Millimeter/submillimeter Array observations of 99.02 GHz free-free and H40$\alpha$ emission from the centre of the nearby starburst galaxy NGC 253. We calculate electron temperatures of 3700-4500 K for the photoionized gas, which agrees with previous measurements. We measure a photoionizing photon production rate of $(3.2\pm0.2)\times10^{53}$ s$^{-1}$ and a star formation rate of $1.73\pm0.12$ M$_\odot$ yr$^{-1}$ within the central 20$\times$10 arcsec, which fall within the broad range of measurements from previous millimetre and radio observations but which are better constrained. We also demonstrate that the dust opacities are ~3 dex higher than inferred from previous near-infrared data, which illustrates the benefits of using millimetre star formation tracers in very dusty sources.

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G. J. Bendo, R. J. Beswick, M. J. D'Cruze, C. Dickinson, G. A. Fuller, T. W. B. Muxlow. 2015-04-08. ALMA observations of 99 GHz free-free and H40$\alpha$ line emission from star formation in the centre of NGC 253. https://doi.org/10.1093/mnrasl/slv053

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