The record for the most distant galaxy ever observed may have been broken yet again, according to a statement from Harvard &; Smithsonian Center for Astrophysics. The light source in question, a galaxy the researchers themselves dubbed HD1, traveled 13.5 billion light-years to reach Earth and was later captured by a team of astronomers from the Center for Astrophysics. Two studies have been published in the Astrophysical Journal it Monthly Notices of the Royal Astronomical Society Letters.
Capturing the details of such a distant object is quite a feat.
Fabio Pacucci, lead author of the MNRAS study and co-author of the ApJ study, explains that it is still difficult to understand and especially to describe such a distant source of light. It’s a bit like determining the nationality of a distant ship by examining its flag waving in thick fog and in the midst of a gale. You can see some of the connotations of the flag but you can’t get the full picture.
However, it is possible to develop scenarios and see which are the most plausible.
Maybe it’s a star galaxy.
First, researchers know that the HD1 light source is very bright in the ultraviolet band. The researchers initially assumed that it was a standard star. A star galaxy is a galaxy in which new stars are being created at a very high rate.
However, on closer inspection, the researchers discovered that the rate of formation of this galaxy was 100 stars per year, a rate much higher than that of outburst galaxies.
early universe galaxy
So researchers began to suspect that the stars forming, or rather forming, in this galaxy were not normal stars. What we are observing is a galaxy from the early universe. We observe it at a stage in the universe when the first populations of stars appeared. As Pacucci explains, the first stars that formed in the universe were much more massive, brighter and hotter than the average stars formed today.
HD1 stars may belong to population III
If the stars of HD1 are just this type of star, its particular properties would be more easily explained. The researcher thinks in particular that the information stars of the HD1 galaxy belong to population III. These are stars, now all extinct, which formed during the first phase of star formation in the universe and which were totally devoid of metals. Population III stars can produce more ultraviolet light than normal stars, which would explain in particular the high level of ultraviolet luminosity of HD1.
A supermassive black hole could also be involved.
However, a supermassive black hole could also be put into play to explain this high level of luminosity. The latter would propagate huge amounts of gas and high-energy photons in its surrounding region, which could also explain the extreme level of luminosity.
If it is indeed a black hole, it would be the oldest ever detected, the closest to the moment of the Big Bang of all the primordial black holes ever discovered. Researchers now plan to use the new James Webb Space Telescope to take a closer look at HD1, in part to confirm its distance and find out if it really is the most distant and oldest galaxy ever discovered.