Using optical data of a recently detected gamma ray burst afterglow, astronomers from the Harvard-Smithsonian Center for Astrophysics, Pennsylvania State University and Gemini Observatory, have learned about the chemistry of a galaxy 12.7 billion light-years away. The team discovered that the galaxy contains only one-tenth of the heavy elements found in our Solar System.
This is an artist’s impression of GRB 130606A illuminating interstellar gas in its host galaxy (Gemini Observatory / AURA / Lynette Cook)
NASA’s Swift spacecraft detected this gamma ray burst (GRB) – a flash of gamma rays associated with extremely energetic explosions in distant galaxies – on June 6, 2013. It was labeled GRB 130606A and classified as a long GRB since the event lasted for more than four minutes.
At a distance of 12.7 billion light-years, GRB 130606A is one of the most distant gamma-ray bursts ever found.
The team quickly organized follow-up observations by the MMT Telescope in Arizona and the Gemini North telescope in Hawaii.
“We were able to get right on target in a matter of hours. That speed was crucial in detecting and studying the afterglow,” explained Dr Ryan Chornock of the Harvard-Smithsonian Center for Astrophysics, lead author of a paper accepted for publication in the Astrophysical Journal (preprint at arXiv.org).
A GRB afterglow occurs when jets from the burst slam into surrounding gas, sweeping that material up like a snowplow, heating it, and causing it to glow.
As the afterglow’s light travels through the dead star’s host galaxy, it passes through clouds of interstellar gas. Chemical elements within those clouds absorb light at certain wavelengths, leaving ‘fingerprints.’ By splitting the light into a rainbow spectrum, astronomers can study those fingerprints and learn what gases the distant galaxy contained.
All chemical elements heavier than hydrogen, helium, and lithium had to be created by stars. As a result those heavy elements, which astronomers collectively call ‘metals,’ took time to accumulate. Life could not have existed in the early Universe because the elements of life, including carbon and oxygen, did not exist.
The team found that the GRB galaxy contained only about one-tenth of the metals in our Solar System. Theory suggests that although rocky planets might have been able to form, life probably could not thrive yet.
“At the time this star died, the Universe was still getting ready for life. It didn’t have life yet, but was building the required elements,” Dr Chornock said.
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Bibliographic information: Ryan Chornock et al. 2013. GRB 130606A as a Probe of the Intergalactic Medium and the Interstellar Medium in a Star-forming Galaxy in the First Gyr After the Big Bang. ApJ, accepted for publication; arXiv: 1306.3949
