Astronomers Spot 83 Super-massive Black Holes from Earliest Days of the Universe
Astronomers at the Subaru Telescope in Hawaii recently announced the discovery of 83 quasars, powered by super-massive black holes in the depths of space. Objects like these are found at the centers of galaxies, and they can have masses equal to millions or billions of stars the size of the Sun.
When the light seen from these objects left their source, the Universe was only around five percent of its current age. This discovery greatly increases the number of super-massive black holes (SMBH’s) seen in the early Universe.
“While they are prevalent in the present-day universe, it is unclear when they first formed, and how many of them exist in the distant early universe,” researchers from the National Astronomical Observatory of Japan (NAOJ) report.
This latest batch of SMBH’s, found 13 billion light years from Earth, were imaged by astronomers using the wide-field camera Hyper Suprime-Cam (HSC), mounted to the Subaru Telescope. Previous studies of ancient SMBH’s only searched for the brightest quasars, resulting in the discovery of just the most-massive objects. In this new study, astronomers looked for super-massive black holes like those in our present-day Universe.
A few hundred million years after the Big Bang, the Universe was filled with hydrogen and helium gas, wandering free. However, about the time stars and galaxies were first forming, roughly 13 billion years ago, the neutral hydrogen (which made up about 75% of all normal matter in the Universe) was “re-ionized,” or split into its component protons and electrons.
Astrophysicists are uncertain about the causes of this process, or how the vast amount of energy needed to make this happen was generated. One theory is that the early Universe quickly became filled with powerful quasars which ionized the gas, but this new study does not reveal enough of these objects to have supplied the needed energy. Another theory postulates the formation of numerous galaxies in the early Universe may have provided enough energy to ionize the hydrogen which permeated space at that time.
The processes resulting in the formation of SMBH’s in the earliest days of the Universe remains a mystery. Recent research from the Georgia Institute of Technology suggests that when galaxies form extremely quickly, the process can produce super-massive black holes. Normal star formation during this process might be interrupted, and dark matter (which provides the “glue” holding all galaxies together) can collapse into halos around the nascent galaxy.
Previously, astronomers believed that ultraviolet radiation from nearby galaxies flooding young neighbors would be needed to discourage star formation, providing enough raw material for super-massive black holes to form so quickly. Computer simulations conducted by GA Tech researchers showed ultraviolet light would not be needed to allow the quick formation of SMBH’s in the early Universe.
“As we delved deeper, we saw that these sites were undergoing a period of extremely rapid growth. That was the key. The violent and turbulent nature of the rapid assembly, the violent crashing together of the galaxy’s foundations during the galaxy’s birth prevented normal star formation and led to perfect conditions for black hole formation instead,” said John Regan, research fellow in the Centre for Astrophysics and Relativity in Dublin City University.
Nearly all galaxies seen in the modern Universe contain super-massive black holes at their centers. The one near the middle of our own Milky Way Galaxy is thought to have a mass around 4.6 million times greater than that of the Sun.
In addition to providing more information about the number of these objects, this discovery also assists astronomers studying how gas in the early Universe was affected by super-massive black holes like the ones found by astronomers using the Subaru Telescope.