A team of astronomers, including two MIT scientists, have detected the most distant supermassive black hole ever observed. It is at the center of an ultra-bright quasar, the light of which was emitted only 690 million years after the Big Bang. That light has taken about 13 billion years to reach us, a period of time that is almost equal to the age of the universe.
The absolutely gigantic black hole is about 800 million times more massive than our star (and about 200 times more than Sagittarius A , the black hole at the center of the Milky Way), certainly a true Goliath, by standards modern astronomical and an anomaly of the early universe. It is the most distant black hole ever detected, as the universe was barely 5% of its current age.
“Gathering all this mass in less than 690 million years is an enormous challenge for the theories of the supermassive growth of the black hole “, explains Eduardo Bañados, from Carnegie Mellon University and leader of the study that compiles the journal Nature.
The black hole in question, which has been baptized as J1342 + 0928, is located in the center of a super bright disk of gas, in the heart of a galaxy, forming an object known as a quasar, an emitting source of X-rays, light visible and other wavelengths and that it is among the brightest objects in the universe.
The discovery
The finding was made thanks to data from three wide-area surveys: Z-band data from the Legacy DECam Survey at the Cerro Tololo Inter-American Observatory in Chile; and infrared data from NASA’s Wide-field Infrared Survey Explorer and UKIRT Infrared Deep Sky Survey.
We already know that black holes do not emit light, as the light is caused by the accretion disk around the black hole, where dust and gas swirl at tremendous speeds, generating immense friction as they are pulled by the massive gravitational force of the black hole. central black hole. But, despite their great brightness, all the quasars found to date are so far away that they cannot be seen with the naked eye, they can only be observed with telescopes. However, they are really valuable tools for studying the early universe, because light can be analyzed to reveal information about the path of hydrogen on its journey to Earth.
The quasar Y J1342 + 0928 is so old that it can tell us about a crucial point in the history of our universe: the Age of Reonization.
Just after the Big Bang, the universe was a kind of dark and hot “primordial soup” on a cosmic scale, rapidly expanding.
As it expanded, it cooled, causing protons and neutrons to begin to combine into ionized hydrogen atoms; And, around 240,000-300,000 years after the Big Bang, these hydrogen atoms attracted electrons, merging into neutral hydrogen.
At this point, light could travel freely through the universe, but it wasn’t until gravity began to pull the first stars and galaxies together in this dark, hydrogen-filled void that starlight appeared … and shortly after If this happened, according to current theories, neutral hydrogen was stirred up by ultraviolet light from these newborn stars, galaxies, quasars, or a combination of the three.
This effect reionized most of the hydrogen in the universe, dividing it into protons and electrons. About 1 billion years after the Big Bang, the reionization process was complete.
However, how is it possible that at the height of reionization, this supermassive black hole already reached 800 million suns? How could he accumulate so much matter?
Analysis of the light from the quasar shows that a significant proportion of the space around it is still neutral hydrogen, 690,000 years after the Big Bang. This means that reionization may have occurred relatively late in the life of the universe.
Astronomers estimate that there must be between 20 and 100 quasars as bright and distant as this one, hence this research is so relevant, as it will help us explain what happened in the universe when it was so young and, hopefully, we can develop a model of galactic evolution that can explain all these phenomena.
“This is a very exciting discovery, found by touring the new generation of sensitive wide-area studies that astronomers are conducting using NASA’s orbiting Wide-field infrared field explorer and ground-based telescopes in Chile and Hawaii.” says Daniel Stern of NASA’s Jet Propulsion Laboratory.
Reference: An 800 million solar mass black hole in a significantly neutral Universe at a redshift of 7.5, Nature (2017). nature.com/articles/doi:10.1038/nature25180
Image credit: Robin Dienel, Carnegie Institution for Science
