First, we need to clear up some definitions. There are many kinds of black holes: some big ones, some small ones, some with electric charges, some without, and some with rapid rotations and others more sedentary. For the purposes of our adventure in this particular tale, I'm going to stick to the simplest possible scenario: a giant black hole with no electric charge and no spin whatsoever.
From a distance the black hole is surprisingly benign. After all, it's just a massive object, pretty much like any other massive object. Gravity is gravity and mass is mass — a black hole with the mass of, say, the sun will pull on you exactly the same as the sun itself. All that's missing is the wonderful heat and light and warmth and radiation. But if you felt like orbiting it at a safe distance, you most certainly could.
In case you are keeping track:
A Weakened Black Hole Allows Its Galaxy To Awaken
Supermassive black holes, weighing millions or even billions of times our Sun's mass, are still only a tiny fraction of the mass of the galaxies they inhabit. But in some cases, the central black hole is the tail wagging the dog. It seems that black holes can run hot or cold when it comes to either enhancing or squelching star birth inside a cluster of galaxies.
Unraveling this mystery required the combined power of NASA's Hubble Space Telescope, NASA's Chandra X-ray Observatory, and the Very Large Array (VLA) radio observatory near Socorro, New Mexico.
New technique touted for spotting elusive black hole mergers – Astronomy Now
The Milky Way, like most if not all large galaxies, features a supermassive black hole at its core. Astronomers believe smaller black holes also congregate near the core where it might be possible to detect mergers by their interactions with gas swirling around the much more massive supermassive black hole.
Such mergers are currently detected by the gravitational waves they generate, so-called “ripples” in the fabric of spacetime. They do not, by definition, produce a light signature that would help astronomers pinpoint their locations and glean additional details.
How to observe a 'black hole symphony' using gravitational wave astronomy
Through these findings on black hole gravitational waves, which were first observed in 2015 by the Laser Interferometer Gravitational-Wave Observatories (LIGO) in Louisiana and Washington, researchers have learned exciting details about these invisible objects and developed theories and projections on everything from their sizes to their physical properties.
Still, limitations in LIGO and other observation technologies have kept scientists from grasping a more complete picture of black holes, and one of the largest gaps in knowledge concerns a certain type of black hole: those of intermediate-mass, or black holes that fall somewhere between supermassive (at least a million times greater than our sun) and stellar (think: smaller, though still 5 to 50 times greater than the mass of our sun).
Other things to check out:
Hypervelocity Star Booted out of Our Galaxy by Supermassive Black Hole | Digital Trends
Astronomers have detected a hypervelocity star called S5-HVS1 traveling through our galaxy at a tremendous speed of 2.3 million miles per hour (1,017 km/s), making it the third-fastest star ever recorded.
The star is traveling fast enough that it will leave the Milky Way and shoot off into the massive space between galaxies. "S5-HVS1's velocity is so high that it will inevitably leave the galaxy and never return," Dr. Douglas Boubert, an astronomer at the University of Oxford, explained in a statement .
Milky Way's Supermassive Black Hole Flings Star Away at 6,000,000 km/h
An artist’s impression of the Milky Way’s big black hole flinging the star from the galaxy’s center. Credit: James Josephides (Swinburne Astronomy Productions)
The eviction occurred about five million years ago, around the time when our ancestors were just learning to walk upright.
“We traced this star’s journey back to the center of our galaxy, which is pretty exciting,” said Professor Da Costa from the ANU Research School of Astronomy and Astrophysics.
Hyper-fast star ejected by supermassive black hole | Cosmos
An artist's impression of the Milky Way's big black hole flinging the star from the galaxy's centre.
Astronomers have discovered a star travelling at more than six million kilometres an hour through the Milky Way after being flung from our galaxy's centre by a supermassive black hole.
The eviction occurred about five million years ago, an international team reports in the Monthly Notices of the Royal Astronomical Society , and the star is moving so quickly that it will leave the Milky Way in about 100 million years, never to return.
Huge black holes might have merging baby black holes around them | Astronomy.com
When the LIGO collaboration first detected the spacetime ripples of a gravitational wave it came from the merger of two black holes. To date, scientists have detected at least ten pairs of black holes spiraling into and combining with each other.
Now, a group of researchers has proposed a new possibility. Black holes in the accretion disk surrounding a galaxy’s central supermassive black hole might gather in similar orbits. This could lead black holes to go through multiple mergers, growing larger each time.
Happening on Twitter
Take a Fun Trip into a Black Hole: What's It Like Inside? https://t.co/41l59CuGOn https://t.co/PhXF00jQTs SPACEdotcom (from NYC) Mon Nov 18 13:24:06 +0000 2019
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