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

17 May 2018

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. The model indicates that the star formation became inactive once after the first ignition, and then revived at the epoch of the ALMA observations; 500 million years after the Big Bang.

The new details revealed that light from a galaxy dubbed MACS1149-JD1 was 13.28 billion light years old, an global team reported in the scientific journal Nature.

The real breakthrough was the detection of oxygen in the galaxy, which is observable in the Leo constellation, though not with the naked eye. Oxygen is created inside of stars and it is released as a gas cloud when those stars die.

Bouwens emphasised that it is still not clear whether the stellar activity detected in MACS1149-JD1 occurred in other regions in the early Universe, but he added that the discovery will spur similar studies of other galaxies. Although we are seeing it now, the gas glow from this far-off galaxy was likely emitted 500 million years after the universe was first formed.

The study, published today in the journal Nature, was an global and collaborative effort.

An global team of astronomers led by Hashimoto used ALMA to observe a distant galaxy called MACS1149-JD1.

Based on the wavelength of the light, stretched from infrared to microwave by the expansion of the Universe, the team ascertained that the galaxy is 13.28 billion light-years away.

Along with the ancient oxygen signal, the VLT also picked up a weaker signal of hydrogen emission which is consistent with the distance from the oxygen observation.

By measuring the precise change in the wavelength of this light - from infrared to millimeter - the team determined that this telltale signal of oxygen traveled 13.28 billion light-years to reach us, making it the most distant signature of oxygen ever detected by any telescope.

ALMA has set the record for the most distant known source several times. In 2016, Akio Inoue at Osaka Sangyo University and his colleagues found the signal of oxygen at 13.1 billion light-years away with ALMA. The massive newborn stars in the second burst ionized the oxygen between the stars; it is those emissions that have been detected with ALMA. Both teams merged efforts to achieve this new record.

The Universe's very early years are notoriously hard to study.

The team reconstructed the earlier history of MACS1149-JD1 using infrared data taken with the NASA/ESA Hubble Space Telescope and NASA Spitzer Space Telescope. "This has very exciting implications for finding "cosmic dawn" when the first galaxies emerged", Laporte said in another statement, referring to the time when the earliest galaxies emerged from the complete darkness of the early universe.

By establishing the age of MACS1149-JD1, the team has effectively demonstrated the existence of early galaxies to times earlier than those where we can now directly detect them. With MACS1149-JD1, we have managed to probe history beyond the limits of when we can actually detect galaxies with current facilities. Whether MACS1149-JD1 is just an outlier or the tip of an iceberg will have to wait for more observations. "Since we are all made of processed stellar material, this is really finding our own origins", said Richard Ellis, senior astronomer at UCL and co-author of the new paper detailing this research. A calculation based on the latest cosmological parameters measured with Planck (H0=67.3 km/s/Mpc, Ωm=0.315, Λ=0.685: Planck 2013 Results) yields the distance of 13.28 billion light-years.

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