Oldest Oxygen Shows Earliest Stars Formed 250 Million Years After Big Bang

James Marshall
May 17, 2018

According to Takuya Hashimoto, representing the Japanese University of Osaka, this invention allows to significantly extend the boundary of the Universe studied by scientists. When ALMA's antennas (which range from 7 to 12 meters in diameter) are configured in different ways, the array is capable of zooming in on some of the most distant cosmic objects in the universe, as well as capturing images that are clearer than those produced by the Hubble Space Telescope.

"This galaxy is seen at a time when the universe was only 500m years old and yet it already has a population of mature stars", said Nicolas Laporte, a researcher at University College London in the United Kingdom and second author of the new paper.

Using the giant ALMA telescope in Chile, researchers were able to observe the distant galaxy MACS1149-JD1 when it was just 550 million years old, a time when it contained stars that were about 300 million years old.

For MACS1149-JD1 to contain substantial amounts of oxygen, many stars must have already gone through that whole life cycle. An global team of astronomers used ALMA to observe a distant galaxy called MACS1149-JD1. They found that the observed brightness of the galaxy is well-explained by a model where the onset of star formation corresponds to only 250 million years after the Universe began. "It is truly remarkable that ALMA detected an emission line - the fingerprint of a particular element - at such a record-breaking distance". The recognition of oxygen in MACS1149-JD1 demonstrates that these prior ages of stars had been now shaped and ousted oxygen by only 500 million years after the start of the Universe.

Before the first stars kicked on, the universe was a relatively boring place, consisting primarily of radiation leftover from the Big Bang, as well as hydrogen and helium. While this ALMA study has indirectly dated that time to 250 million years after the Big Bang, the earliest direct detection was announced earlier this year, in the form of an ionized hydrogen signature hailing from when our universe was a mere 180 million years old. Photo: ALMA (ESO/NAOJ/NRAO), NASA/ESA Hubble Space Telescope, W. Zheng (JHU), M. Postman (STScI), the CLASH Team, Hashimoto et al.

"The mature stellar population in MACS1149-JD1 implies that stars were forming back to even earlier times, beyond what we can now see with our telescopes". "This has very exciting implications for finding "Cosmic Dawn" when the first galaxies emerged".

Richard Ellis, senior astronomer at UCL and co-author of the paper, concludes: "Determining when cosmic dawn occurred is akin to the Holy Grail of cosmology and galaxy formation".

The find comes thanks to observations of an ancient galaxy known as MACS1149-JD1, first detected in 2012. "Since we are all made of processed stellar material, this is really finding our own origins". Several months later, Nicolas Laporte of University College London used ALMA to detect oxygen 13.2 billion years ago.

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