Space Telescope Observations of Warm Dust in Low Surface Brightness Galaxies
Date
2017-12-19
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Abstract
Blue in color, a low star formation rate, dark matter dominated, and low in metallicity, low surface brightness (LSB) galaxies questions the current understanding of galactic formation by representing an alternative to the classical Hubble sequence. LSB galaxies are proposed to be the result of galactic overfeeding as high velocity clouds (HVC) weaken the metal content in gas, hindering the process of forming more stars. Although HVCs can dilute the metallicity content, it cannot destroy dust grains. Without HVC dilution, it is expected that there is a correlation between metallicity and dust. To get the dust content, we created warm dust maps using the Independent Component Analysis, first introduced by Meidt et al. (2012), on the Spitzer IRAC 3.6 and 4.5μm images on 10 LSB galaxies: UGC 628, UGC 731, UGC 11748, UGC 11820, UGC 1230, F415-3, F583-5, F584-2, UGC 5709, F563-V2. The images were decomposed to trace either the old stellar population or the contaminant sources of emission, which included Polycyclic Aromatic Hydrocarbons, warm dust, intermediate-age asymptotic giant branch stars and red supergiant stars. We find that in our sample, warm dust is present in all the galaxies, old stellar populations reside in the center and unlike their high surface brightness (HSB) galaxy counterparts, there are a small number of larger HII regions that do not show preference to the center. In the future, we hope to refine our methods, increase our sample size, and convert our contaminant images into dust maps to compare with the metallicity content of each galaxy. Such studies will determine if low surface brightness galaxies are the outcome of galactic overfeeding and provide insight into the evolutionary path of these galaxies.
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galaxy, astronomy