Tuesday, February 14, 2023

Carbonaceous dust grains within galaxies seen in the first billion years of cosmic time


Interstellar dust captures a significant fraction of elements heavier than helium in the solid state and is an indispensable component both in theory and observations of galaxy evolution. However, the astrophysical origin of various types of dust grains remains an open question, especially in the early Universe. Here we report direct evidence for the presence of carbonaceous grain from the detection of the broad UV absorption feature around 2175 Å in deep near-infrared spectra of galaxies up to the first billion years of cosmic time, at a redshift (𝑧) of ∼ 7. 

Our results suggest a more rapid production scenario, likely in supernova (SN) ejecta.

The previous scenario considered was giant branch/AGB stellar evolution. There are some issues with the supernova scenario, particularly in that supernova shock waves tend to vaporize surrounding dust grains produced in previous phases.

Figure 1. Spectrum taken by JWST/NIRSpec of JADES-GS-z6-0 at redshift z = 6.71. a...

I like this figure a lot--it shows the UV bump around 2000 Å extremely clearly.

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Thermal vacuum testing for the Europa Clipper

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