The nuclei (or center of galaxies) are pretty crazy !! And it wasn’t until the 40s that we knew what makes up that central region of our very own galaxy the Milky Way!
American astronomer Carl Seyfert took images of galaxies specifically spiral galaxies and he noticed that they have a very very bright nuclei and they were emitting intense amounts of ultraviolet emissions.
Even more interesting is that the luminosity a.k.a. the the total amount of energy radiated by a star or celestial object, that we re able to visually see, that it was variable and on scales on weeks meaning it was inconsistent with energy output, one week it may be reading high amounts of energy and later that week the energy levels may be lower.
This means something had to be causing the inconsistency of luminosity that the object had to have been fluctuating for a reason.
Another interesting thing that was found was that the gas in the center was moving much much faster than expected. So using the twin Keck Observatory telescopes astronomers gazed directly at the Milky Way Center and using their AO systems have been able to confirm that there is super massive black hole at the center of our galaxy.
They did this using their AO systems also known as adaptive optics system which was built to get super clear images of things beyond our solar system.
You see when we’re capturing images from the ground here on Earth but taken of space lightyears away theres a lot of interference and mainly from our own atmosphere!
The AO system used to rely on the light of a star that was bright and close by a targeted celestial object to correct any disturbances but there aren’t always enough bright stars to use as a reference point when looking at only 1% of the sky.
So this is where the LASERS COME IN, astronomers developed the Laser Guide Star Adaptive Optics system which points a laser to our atmosphere in the designated place of observing and it excites sodium atoms which sit in an atmospheric layer about 60 miles above Earth.
When these atoms in the sodium layers of our atmosphere are excited it creates an artificial star to measure the exact atmospheric distortions. Those measurements are calculated in when adjusting the mirror, which can change shape 1000 times per second! And once this adjustment is made it’s able to capture super clear images of celestial objects by cutting out our annoying atmosphere.
NOW BACK TO OUR GALACTIC CENTER..
The Keck observatory looked at the center and observed stellar motions to be really interesting.
The stars near the center were orbiting similarly to how the planets orbit the sun in our solar system. When closer to the center they whip around faster, meaning there is something super strong in gravity there.
This could only be due to one main factor VERY VERY STRONG GRAVITY.
And the stellar velocities were calculated on magnitudes of thousands of km/s.
The only thing in the universe known to have a gravitational field of such strength is a super massive black hole and four million times the mass of the sun!
Now what was also being calculated we’re massive jets of plasma coming out of the black hole.
So the black holes at the center of the galaxy should be spinning and they should have very strong amounts of angular momentum. When plasma or gas falls upon the black hole, it gets accelerated along the poles and escapes as a very high-energy, relativistic plasma, twin jets pointing out into space. But we can get into that another time… If you want to learn about quasars check out my video here!