The farthest galaxy is improving our model of the history of the universe

To look at the universe with a telescope means to look back in time, because the speed of light is so slow that even the light of stars in the environment in our own galaxy takes years or millennia to reach us. reach. As such, the very distant galaxies also offer humans a glimpse into the past of the universe – making the discovery of the farthest galaxy ever found even the oldest.

According to a new study Published December 14 in the journal Nature Astronomy, astronomers have confirmed the most distant galaxy in our universe. The galaxy, called GN-z11, is so far away that it is believed to be the boundary of the universe at 13.4 billion light-years, or 134 non-million kilometers, from Earth, which means that the light we see from it, Left 4 billion years ago – only 400 million years after the big bang.

Nobunari Kashikawa of the School of Science at the University of Tokyo, a co-author of the study, explained to Salon that the current designation for GN-z11 as the “oldest” galaxy may be short-lived, as telescopes constantly scan the sky.

“GN-z11 is the farthest galaxy we know so far today, and maybe we’ll find a star galaxy tomorrow,” Kashikawa wrote in an email.

Although the distant galaxy was originally spotted in 2016 by the Hubble Space Telescope, Kashikawa and his team used the Keck I telescope in Hawaii to confirm its age and distance. At the time of its discovery, astronomers estimated that it was 13.4 billion light-years away, based on the discovery of a fracture known as the ‘Lyman fracture’, in the ‘spectrum characteristic of distant galaxies’. ‘, Kashikawa explained. .

The attempt to detect such a distant, dim galaxy pushed the Hubble Space Telescope to its technological limit.

“Our spectroscopic observations show that the galaxy is even further away than we originally thought, just at the distance limit of what Hubble can observe,” Gabriel Brammer, author of the 2016 study, said in a statement. statement.

Astronomers measure the distance of a galaxy by determining its redshift, which measures how fast it moves from Earth. As the universe is expanding, every object in the sky that is not gravity to our own galaxy is off the earth; while doing so, these objects will ‘ light extends in longer and thus redder wavelengths. The farther the galaxy, the greater the redshift.

To determine how far GN-z11 was from Earth, Kashikawa’s team studied its spectral characteristics, as the observations of the Hubble Space Telescope were limited.

“Even the Hubble cannot solve ultraviolet emission lines to the extent we needed,” Kashikawa said in a statement. “We therefore turned to a more current ground spectrograph, a tool for measuring emission lines, called MOSFIRE, which is mounted on the Keck I Telescope in Hawaii. “

Kashikawa told Salon it is “difficult” to determine if there really is a break in the spectrum or not. Specifically, the team threatened to look at ultraviolet light to find the red-shifted chemical signatures. What this amounted to was having the right equipment to confirm and identify the spectral fraction.

“Since the wavelength cannot be measured accurately, the accuracy of determining the distance to the galaxy was uncertain,” Kashikawa told Salon in an email. “Once we believe that the carbon and oxygen emission lines we have detected at this time are real, it is not that difficult to calculate the distance from them.”

Even though this galaxy is far, far away, astronomers are hopeful that it contains information we can learn about our own galaxy and the universe.

“The detected light of carbon and oxygen indicates special physical conditions not found in modern galaxies,” Kashikawa told Salon. “The age of GN-z11 is estimated at only 70 million years and the estimated mass of a billion times the sun (the star component) indicates that this young galaxy was born and grew rapidly.”

Kashikawa added: “The fact that carbon and oxygen were found in GN-z11 indicates that this galaxy is not the first (metal-free) galaxy in the universe.” Since elements heavier than hydrogen and helium are forged only in massive stars, the presence of heavier elements such as carbon indicates that the stars in the galaxy are at least second generation, meaning that one generation of large suns has already lived and died, and their metals drove the galaxy inside.

This means, Kashikawa said, that the first galaxies in the universe are still “in a more distant universe unknown to mankind.”

Next year will be a big year for astronomy, especially in terms of how we better understand the universe.

“The boundary of the farthest corners of space is expected to expand dramatically,” Kashikawa said.

And that’s in part because the James Webb Space Telescope will launch from French Guiana on October 31, 2021, and will build on the legacy of the Hubble Telescope. It will specifically observe the infrared universe and detect light from distant, old galaxies. Infrared light can not be detected well from Earth due to disturbance of the atmosphere, and so the space-based telescope is needed to explore the universe in infrared.

“The [James Webb Space Telescope] observatories will detect light from the first generation of galaxies that formed after the big bang in the early universe and study the atmosphere of nearby exoplanets for possible signs of habitability, “said Eric Smith, NASA Webb’s program scientist at the agency’s headquarters, in ‘ a statement previously.