Two ‘previously inaccessible’ galaxies were discovered by scientists around 29 billion light-years from Earth.
The two ‘heavily dust-obscured’ galaxies – called REBELS-12-2 and REBELS-29-2 – were found during observations with the ALMA radio telescopes in Chile’s Atacama Desert.
Both were previously undetectable to the optical lens of NASA’s Hubble Space Telescope, because they were hidden behind curtains of cosmic dust.
According to the astronomers, up to 20% of all galaxies within the universe have been found.
With the help of the giant ALMA radio telescopes (Atacama Large Milimeter Array) in Chile’s Atacama Desert the two invisible galaxies ‘suddenly appeared’. As this graphic shows ALMA offers a five-fold spatial resolution than Hubble Space Telescope. This was crucial to their discovery
However, many of these “missing” galaxies can be discovered by equipment like the James Webb Space Telescope.
This new study was done by scientists at University of Copenhagen’s Niels Bohr Institute.
Pascal Oesch (associate professor at the Niels Bohr institute) said, “We were looking, a sample, of very distant galaxies which we already knew existed through the Hubble Space Telescope,”
“Then, we realized that one of the two had a neighbor that we hadn’t expected to be there.”
Hubble is unable to see these two galaxies because they are both surrounded by dust.
Hubble was launched into low Earth orbit in 1990, while the ground-based ALMA (Atacama Large Milimeter Array) radio telescopes began scientific observations in 2011.
ALMA, which is five times more precise than Hubble Space Telescope’s spatial resolution, was the key to its discovery.
ALMA uses the combined light from all its 66 antennae in order to produce a high-resolution image and spectrum of the sky. It can also capture radio waves that are emitted by the darkest and coldest parts of the universe.
Antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, set against the splendour of the Milky Way
Team says that the light of both REBELS-12-2 & REBELS-2-9-2 has traveled about 13 billion year to reach Earth.
REBELS-12-2 was compared to REBELS-229-2, and the results showed that between 10 and 20% of the early universe’s sources (about 13 Billion years ago) may be still hidden behind cosmic debris.
‘Our discovery demonstrates that up to one in five of the earliest galaxies may have been missing from our map of the heavens,’ said Professor Oesch.
The James Webb Space Telescope, which is expected to be launched into orbit on December 22 this year after 25 years in development, will help experts better understand when and how galaxies formed.
The general consensus is that the oldest galaxies were formed in the first 100 million years following the Big Bang. However, astronomers are still not sure how they got there.
Hubble Space telescope is over 30 years old. NASA captured Hubble’s drift over Earth in this NASA photo on May 19, 2009.
NASA’s James Webb Space Telescope (NASA) is the biggest, most powerful and complex space science telescope ever made.
James Webb is one of many things that help scientists see through cosmic dust better than Hubble and ALMA.
Professor Oesch stated that the next step was to find galaxies not yet identified. There are many more than we think.’That’s where the James Webb Telescope will be a huge step forward.
“It will be more sensitive than Hubble. It can also investigate longer wavelengths. This should enable us to find these hidden galaxies easily.
Nature has published this new study.