Determining the dust composition of GRB host galaxies

Document Type

Conference Proceeding

Publication Title

Proceedings of Science

Publication Date



Gamma ray burst (GRB) spectral energy distributions (SEDs) are typically fit with a dust extinction template with pre-determined graphite-to-silicate ratios (see Figure 1) to extract the approximate dust composition. These templates are an oversimplification of composition and often rely on non-physical fitting parameters. We instead propose a model that allows for the ratio of graphite to silicate to vary, enabling us to detect smaller amounts of graphite in GRB host galaxies than previously determined with physical model parameters relying on fixed ratios of graphite to silicate column densities. Data from the literature was used to construct GRB SEDs. The optical depths of astronomical silicates and graphite were calculated for a typical size distribution of dust particles and fit to the SEDs using our fitting function. A linear regression produced the best-fit and errors to the dust column densities.



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