(ORDO NEWS) — An international team of astronomers has discovered the most distant astronomical object known to date – a galaxy. This candidate galaxy, designated HD1, is about 13.5 billion light-years away.
Regarding the device of the HD1 galaxy, scientists offer two versions. In the first scenario, the galaxy could form stars at a surprisingly high rate and even contain population III stars – which scientists have never been able to observe until now.
An alternative hypothesis suggests that the HD1 galaxy contains a supermassive black hole with a mass of about 100 million solar masses.
The HD1 galaxy is extremely bright when observed in the ultraviolet (UV) range. This indicates the high-energy processes in the galaxy.
At first, scientists assumed that the HD1 galaxy is a standard starburst galaxy, that is, a galaxy with an increased rate of formation of new stars.
However, as a result of calculations of the rate of formation of stars in the HD1 galaxy, an “incredibly high” value was obtained – about 100 stars per year.
This value was at least 10 times higher than the expected value of the star formation rate for galaxies of this class.
Then the researchers suggested that the HD1 galaxy can form unusual stars.
The very first generation of stars in the universe, called population III, were more massive, brighter, and hotter than today’s stars.
If we assume that the stars forming in the HD1 galaxy belong to population III, then the properties of the galaxy are explained much more easily.
The fact is that population III stars are able to radiate more energy in the UV range than ordinary stars, and this fact can explain the extremely high luminosity of the HD1 galaxy in this range of the electromagnetic spectrum, the authors explained.
An alternative explanation is that at the center of the HD1 galaxy, there is a SMBH that absorbs huge amounts of gas, which emits high-energy photons before falling into the black hole, the researchers added.
A series of articles devoted to the discovery and study of the properties of the HD1 galaxy has been published in the Astrophysical Journal, Monthly Notices of the Royal Astronomical Society Letters and Monthly Notices of the Royal Astronomical Society.
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