The most distant astronomical object in space is a galaxy that has been recently seen by an international team of astronomers, including researchers at the Center for Astrophysics-Harvard & Smithsonian.
A candidate galaxy, designated HD1, is about 13.5 billion light-years away and is described Thursday in the Astrophysical Journal. In an accompanying article published in the Royal Astronomical Society’s Monthly Notices of Letters, scientists are starting to guess what exactly a galaxy is.
The Team’s Observations About The HD1
The team came up with two ideas-
HD1 is capable of star formation at an astonishing rate and may well be home to the Population III star, the first star in the universe never seen before.
Alternatively, HD1 could contain a supermassive black hole with a mass about 100 million times that of our Sun.
Answering questions about the nature of distant sources can be tricky, says Fabio Pacucci, lead author of the MNRAS study, co-author of the ApJ paper, and astronomer at the Center for Astrophysics. – It’s like guessing your nationality.
A ship from the flag flies away from the shore with the ship in the midst of a storm and thick fog. Some of the colors and shapes of the flag may be visible, but not all. Ultimately, this is a long game of analysis and eliminating nonsensical scenarios.”
Characteristics Of HD1
HD1 is very bright in ultraviolet light. In explanation, Pacucci says, “Some kind of energy process is going on there, or better yet, it happened billions of years ago.”
The researchers hypothesized that HD1 was a standard stellar bursting galaxy that produces stars at a high rate. However, by counting the number of stars that HD1 produces, “an astonishing rate – HD1 will produce more than 100 stars per year. That’s more than ten times what we would expect for this galaxy.”
That’s when the team began to suspect that HD1 couldn’t form a normal, mediocre star.
Reason For The Scientists’ Assumptions
Pacucci said the first star clusters formed in the universe were more massive, brighter and hotter than the stars of today. It’s easier to explain. In fact, Population III stars can emit more ultraviolet light than normal stars, which could explain the extreme ultraviolet luminosity of HD1.”
But supermassive black holes may also explain HD1’s exceptional brightness. Because they absorb huge amounts of gas, they can emit high-energy photons around black holes.
If so, it will be the first supermassive black hole known to mankind, and will be observed much closer to the Big Bang than the current record holder.
Problems In Study Of HD1
“HD1 represents a giant baby in the early universe’s delivery room ,” said Avi Loeb, an astronomer at the Center for Astrophysics and co-author of the MNRAS “It breaks the highest quasar redshift on record by almost a factor of two, a remarkable feat.”HD1 was discovered after over 1200 hours of observation with Subaru, VISTA, UK Infrared Telescope and Spitzer Space Telescope.
It was very difficult to find HD1 among more than 700,000 objects, says Yuichi Harikane, an astronomer at the University of Tokyo who discovered the galaxy. The red color of HD1 matched the expected properties of a galaxy 13.5 billion light-years away, remarkably well. I got goosebumps when I found it.”
The team conducted a follow-up using the Atacama Large Millimeter/Submillimeter Array (ALMA), which identified a distance that was 100 million light-years greater than GNz11, the current record holder for the most distant galaxy.
How Will James Webb Help To Find HD1?
The team is using the James Webb Space Telescope to monitor HD1 again soon to determine its distance from Earth. If current calculations are correct, HD1 would be the most distant and oldest galaxy in history. The same observations allow the team to take a deeper look into HD1’s personality and see if one of their theories is correct.
Formed hundreds of millions of years after the Big Bang, the black hole in HD1 would have grown from a huge seed at an unprecedented rate,” says Loeb. “Again, nature seems to be more ingenious than we are.”