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SUMMARY:Carbonaceous dust grains within galaxies seen in the first billion
  years of cosmic time - Joris Witstok
DTSTART:20230301T134000Z
DTEND:20230301T140500Z
UID:TALK197806@talks.cam.ac.uk
CONTACT:Hannah Uebler
DESCRIPTION:Interstellar dust captures a significant fraction of elements 
 heavier than helium in the solid state and is an indispensable component b
 oth in theory and observations of galaxy evolution. Dust emission is gener
 ally the primary coolant of the interstellar medium (ISM) and facilitates 
 the gravitational collapse and fragmentation of gas clouds from which star
 s form\, while altering the emission spectrum of galaxies from ultraviolet
  (UV) to far-infrared wavelengths through the reprocessing of starlight. H
 owever\, the astrophysical origin of various types of dust grains remains 
 an open question\, especially in the early Universe. I will present direct
  evidence for the presence of carbonaceous grains from the detection of th
 e 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. This dust attenuation feature has previously only been observed
  spectroscopically in older\, more evolved galaxies at redshifts of z < 3.
  The carbonaceous grains giving rise to this feature are often thought to 
 be produced on timescales of hundreds of millions of years by asymptotic g
 iant branch (AGB) stars. These results suggest a more rapid production sce
 nario\, likely in supernova (SN) ejecta.
LOCATION:The Hoyle Lecture Theatre + Zoom 
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