3.2 Uncovering the Origins of Supermassive Black Holes
The number of actively feeding black holes peaked 3,000,000,000 years after the Big Bang and then began falling, with relatively few active quasars now. This raises the question of how these black holes initially formed and grew, such that some were able to reach 1,000,000,000 solar masses. There are three ways to form black holes:
- When a star 10-50 times the mass of the sun dies, it can form a black hole.
- A cluster of stars that die together can form a black hole of roughly 1,000 times the mass of the sun.
- In the early universe, a pre-galactic gas disc could become sufficiently dense for a black hole to form at its center without an intermediary star. This is known as a direct collapse black hole. These black holes can be 10,000-1,000,000 times the mass of the sun.
One current challenge facing astrophysicists is differentiating between these three different pathways to determine how supermassive black holes originated.
- In a direct collapse black hole, there will be a period where the black hole’s mass is greater than the stellar mass of the galaxy it is situated in, contrary to what we observe in the nearby universe.
- The James Webb Space Telescope, scheduled to launch on October 31, 2021, will be equipped to detect galaxies of this nature.
Black holes are typically in a fasting state, with a relatively small amount of gas in their accretion discs.
- After galactic mergers, the black holes can acquire enough gas in their accretion discs to turn into quasars.
- These mergers produce a wide variety of electromagnetic signatures, allowing us to locate them with precision. This technique is known as multi-messenger astronomy.
This is an exciting time in astrophysics, as researchers continue to develop a more detailed understanding of our universe.
- LIGO researchers recently figured out the equations that govern hydrodynamics near the Schwarzchild radius of a black hole, a computationally-intensive problem.
- The James Webb Space Telescope will soon observe some of the earliest black holes in the distant universe.
- The Laser Interferometer Space Antenna, or LISA, will soon be able to detect galactic mergers, allowing us to see supermassive black holes as they enter their ‘feeding’ periods.