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arXiv · 1909.04629

An ALMA-HST Study of Millimeter Dust Emission and Star Clusters

J. A. Turner·D. A. Dale·A. Adamo·D. Calzetti·K. Grasha·E. K. Grebel·K. E. Johnson·J. C. Lee·L. J. Smith·I. Yoon
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Abstract

We present results from a joint ALMA-HST study of the nearby spiral galaxy NGC 628. We combine the HST LEGUS database of over 1000 stellar clusters in NGC 628 with ALMA Cycle 4 millimeter/submillimeter observations of the cold dust continuum that span ~15 square kpc including the nuclear region and western portions of the galaxy's disk. The resolution -- 1.1" or approximately 50 pc at the distance of NGC 628 -- allows us to constrain the spatial variations in the slope of the millimeter dust continuum as a function of the ages and masses of the nearby stellar clusters. Our results indicate an excess of dust emission in the millimeter assuming a typical cold dust model for a normal star-forming galaxy, but little correlation of the dust continuum slope with stellar cluster age or mass. For the depth and spatial coverage of these observations, we cannot substantiate the millimeter/submillimeter excess arising from the processing of dust grains by the local interstellar radiation field. We detect a bright unknown source in NGC 628 in ALMA bands 4 and 7 with no counterparts at other wavelengths from ancillary data. We speculate this is possibly a dust obscured supernova.

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J. A. Turner, D. A. Dale, A. Adamo, D. Calzetti, K. Grasha, E. K. Grebel, K. E. Johnson, J. C. Lee, L. J. Smith, I. Yoon. 2019-09-10. An ALMA-HST Study of Millimeter Dust Emission and Star Clusters. https://doi.org/10.3847/1538-4357%2Fab3faa

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