Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have spotted huge clouds of carbon gas around several young starburst galaxies in the early Universe — the first confirmation that carbon generated inside early stars has spread beyond their host galaxies.
An artist’s impression of a carbon halo around a young star-forming galaxy. Image credit: National Astronomical Observatory of Japan.
“Heavy elements such as carbon and oxygen did not exist in the Universe at the time of the Big Bang. They were formed later by nuclear fusion in stars,” said lead author Dr. Seiji Fujimoto from the University of Copenhagen and colleagues from Europe and Japan.
“However, it is not yet understood how these elements spread throughout the Universe.”
In the study, the team analyzed ALMA data for 18 star-forming galaxies located 12.5-13 billion light-years away.
“We examined the ALMA Science Archive thoroughly and collected all the data that contain radio signals from carbon ions in galaxies in the early Universe, only one billion years after the Big Bang,” Dr. Fujimoto explained.
“By combining all the data, we achieved unprecedented sensitivity.”
The ALMA observations revealed enormous carbon halos that were approximately 60,000 light-years across.
“The gaseous carbon clouds are almost five times larger than the distribution of stars in the galaxies,” said co-author Professor Masami Ouchi, an astronomer at the National Astronomical Observatory of Japan and the University of Tokyo.
The researchers said that current theoretical models are unable to explain such large carbon clouds around young galaxies.
“Supernova explosions at the final stage of stellar life expel heavy elements formed in the stars,” said co-author Professor Rob Ivison, director for science at the European Southern Observatory (ESO).
“Energetic jets and radiation from supermassive black holes in the centers of the galaxies could also help transport carbon outside of the galaxies and finally to throughout the Universe.”
“We are witnessing this ongoing diffusion process, the earliest environmental pollution in the Universe.”
“Young galaxies seem to eject an amount of carbon-rich gas far exceeding our expectation,” said co-author Professor Andrea Ferrara, of Scuola Normale Superiore di Pisa.
The findings will be published in the Astrophysical Journal.
_____
Seiji Fujimoto et al. 2019. First Identification of 10-kpc Scale [CII] 158um Halos around Star-Forming Galaxies at z=5-7. ApJ, in press; arXiv: 1902.06760
