Astronomers Find The Most Far-Away Galaxy Ever And It's Creating Stars At An Incredible Rate
A group of international astronomers, including a team of researchers from the Center for Astrophysics Harvard & Smithsonian, have published a new research paper documenting their findings concerning HD1 in the Astrophysical Journal. In the paper, scientists hypothesize exactly what the newly found galaxy is.
The new candidate galaxy is very bright in ultraviolet light, which indicates highly energetic activity in HD1. This led astronomers to first theorize that it might be a starburst galaxy, or a galaxy that creates stars at a fairly high rate. But after looking a bit closer, they discovered that the galaxy was producing stars at a rate of 100 stars annually, which is 10 times higher than a typical starburst galaxy. This caused the teams to reconsider.
“Answering questions about the nature of a source so far away can be challenging,” noted Fabio Pacucci, lead author of the MNRAS study, and co-author of the discovery paper. “It’s like guessing the nationality of a ship from the flag it flies, while being faraway ashore, with the vessel in the middle of a gale and dense fog. One can maybe see some colors and shapes of the flag, but not the entirety. It’s ultimately a long game of analysis and exclusion of implausible scenarios.”
Two ideas have come to the forefront as to what HD1 may be. The first is that it is forming stars at an astonishing rate, and it could possibly be the home to Population III stars. These unique stars are essentially the universe’s very first stars, which if true have never been observed until now. The second hypothesis is that HD1 could contain a supermassive black hole that is 100 million times the mass of our Sun.
“The very first population of stars that formed in the universe were more massive, more luminous and hotter than modern stars,” Pacucci says. “If we assume the stars produced in HD1 are these first, or Population III, stars, then its properties could be explained more easily. In fact, Population III stars are capable of producing more UV light than normal stars, which could clarify the extreme ultraviolet luminosity of HD1.”
However, that still leaves the possibility of HD1 being a supermassive black hole, which could also explain the galaxy’s extreme luminosity. As the black hole chomps down on enormous amounts of gas, high-energy photons may be emitted by the region around the black hole. If this is true, then it would be the earliest supermassive black hole known and seen at a much closer time period to the Big Bang compared to the current record-holder.
Observations included in the new study were made using the Subaru Telescope, VISTA Telescope, UK Infrared Telescope and Spitzer Space Telescope over a period of more than 1,200 hours. The teams will continue their observations with the James Webb Space Telescope once it is ready, allowing them to verify its distance from Earth.
“Forming a few hundred million years after the Big Bang, a black hole in HD1 must have grown out of a massive seed at an unprecedented rate,” states Loeb. “Once again, nature appears to be more imaginative than we are.”
Top Image Courtesy of Harikane et al.
