Two articles, one published in the journal “Nature” and one published in the “Astrophysical Journal Letters”, describe different aspects of a research that led to the discovery of the oldest known supermassive black hole. According to an estimate it formed about 690 million years after the Big Bang and it’s difficult to explain how it reached 800 million times the Sun’s mass. Labeled as Ulas J134208.10+092838.61 or more simply as J1342+0928, it may have formed during the so-called reionization period.
J1342+0928 is a very active supermassive black hole strongly heating up gas and dust that orbit it with the consequence that they emit a huge amount of electromagnetic radiation in what is called a quasar. Despite this, at a distance of about 13 billion light years, it took patients examinations of observations made with various telescopes to be able to identify and study it.
The discovery of J1342+0928 came in two phases. Initially, the researchers combined data collected in the DECam Legacy Survey (DECaLS) survey, by NASA’s WISE Space Telescope and in the United Kingdom Infrared Telescope Deep Sky Survey (UKIDSS) to identify potential targets at extreme distances. Subsequently, they conducted observations with the Folded-port InfraRed Echellette (FIRE) instrument on the Magellan telescopes in Chile, the antennas of IRAM/Noema Array in France and the Very Large Array radio telescope in New Mexico.
The formation of J1342+0928 may have occurred during the period of reionization, a crucial moment in the history of the universe. Much of the hydrogen surrounding the supermassive black hole is neutral, indicating that it’s not only the most distant found yet but is also the first dating back to a period when the universe had not yet reionized. This can provide new information about that period when large galaxies and supermassive black holes started forming with a considerable activity.
The enormous mass of J1342+0928 is in itself a mystery because it’s difficult to understand how it was possible to reach 800 million solar masses when the universe was still very young in astronomical terms. In June 2017, a research published in the journal “Monthly Notices of the Royal Astronomical Society” proposed a possible mechanism for supermassive black holes in which they devour large quantities of matter relatively quickly but it needs to be well tested.
According to the researchers there could be between 20 and 100 quasars comparable to J1342+0928 for brightness and distance. At 13 billion light years even an extremely bright source can be really hard to spot. Daniel Stern of NASA’s JPL, among the authors of the article published in “Nature”, stated that the ESA’s Euclid and NASA’s WFIRST space telescopes, which will be launched in the next years, will be able to detect these early supermassive black holes.