- Astronomers discovered 83 previously unknown quasars powered by supermassive black holes.
- These quasars are approximately 13 billion light-years away from Earth.
- The observations revealed that in every cubic giga-light-year there exists a supermassive black hole.
Most large galaxies contain a supermassive black hole in their center. It’s theorized that the infall of matter into the supermassive black holes can result in extremely hot regions where an enormous amount of radiation is emitted, powering the quasar. In simple terms, a quasar represents an extremely luminous active galactic nucleus.
Although quasars were first observed in the early 1960s via radio telescopes, physicists weren’t able to explain these small and incredibly bright objects until the 1980s. As of 2017, the most distant quasar, named ULAS J1342+0928, lies 29.36 billion light-years from Earth.
Recently, an international team of astronomers reported 83 new quasars in the far distant universe. These quasars are approximately 13 billion light-years away from Earth, which means their associated supermassive black holes formed just 800 million years after the Big Bang (13.8 billion years ago).
The findings provide new insights into how black holes affect the physical state of gas in the universe’s first billion years. It tells us how common supermassive black holes are in the early universe. All observations are reported in a series of five papers published in two different journals.
Finding Fainter Quasars
Unlike previous researches that explain only most luminous quasars powered by most massive black holes, the new study investigates several fainter quasars in the far distant universe.
An artistic impression of a quasar | Credit: Yoshiki Matsuoka
The team analyzed data captured by the Subaru Telescope’s Hyper Suprime-Cam component. It’s an 870-megapixel visible-light camera with a broad field-of-view that can cover 7 times the area of the full moon.
From this survey data, researchers picked distant quasar candidates and then performed an in-depth observational campaign to produce the spectra of selected candidates.
It revealed 17 known and 83 previously unknown quasars that are approximately 13 billion light-years away from Earth. This means we’re currently observing these quasars as they existed 13 billion years ago.
100 quasars detected by Subaru Telescope | 83 (top seven rows) of them are newly discovered ones while 17 (bottom two rows) are previously known quasars in the survey area. Due to the cosmic expansion and light absorption in intergalactic space, these quasars appear dark red. | Credit: National Astronomical Observatory of Japan
Astronomers also discovered an interesting thing: In every cubic giga-light-year, there exists a supermassive black hole. To explain this in a better way, they split the universe into imaginary cubes (length of a side is one billion light-years). As per survey data, each cube holds one supermassive black hole.
Quasars Didn’t Cause Reionization
The hydrogen in the universe once contained no charge (neutral) but was later ‘reionized’ (chunked into its components electrons and protons). This process of reionization took place when the first generation of supermassive black holes, galaxies, and stars were born – a few hundred million years after the creation of the universe.
In contrast to the previous hypothesis, this study suggests that the observed number of quasars isn’t large enough to provide sufficient energy for reionization. Thus, reionization might have been caused by the numerous galaxies that began to form in the early universe.