The past five years have brought a spate of astounding black hole observations : the first detection in 2015 of gravitational waves from the collision of two black holes; an unprecedented x-ray look in 2018 at a dozen black holes spinning around the supermassive black hole at the center of the Milky Way; and the first-ever photo of a black hole (at the center of the Messier 87 galaxy) in 2019.
The mere existence of black holes had been an open question, even until the 1990s —how the oldest and biggest ones could possibly have formed so soon after the big bang was particularly vexing . An unshakable belief that a monster supermassive black hole lurked at the center of our own galaxy was only vindicated after more than a decade of work by Nobel-winning physicists Andrea Ghez, Reinhard Genzel, and others .
Not to change the topic here:
Cygnus X-1 contains a 21–solar mass black hole—Implications for massive star winds | Science
If a black hole interacts with a binary companion star, the system emits x-rays and can form a radio jet. The masses of black holes in these x-ray binaries are all lower than those detected using gravitational waves, challenging models of black hole formation from massive stars. Miller-Jones et al. used radio astrometry to refine the distance to Cygnus X-1, a well-studied x-ray binary.
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The x-ray binary Cygnus X-1 contains a black hole with a high mass that challenges stellar evolution models.
New Study: Black Hole May Be Larger Than Expected
A recent study found that the first black hole ever discovered is a lot bigger than scientists first thought.
Black holes are extremely massive space objects whose gravity is so powerful not even light escapes. The black hole, Cygnus X-1, was discovered in 1964. It is well-known for being the object of a friendly bet between two famous scientists.
Researchers found that new observations of Cygnus X-1 showed it is 21 times our sun's mass. That is about 50 percent more massive than scientists had believed.
Black hole visionaries push the boundaries of knowledge in a new film | Science News
Black holes sit on the cusp of the unknowable. Anything that crosses a black hole's threshold is lost forever, trapped by an extreme gravitational pull. That enigmatic quality makes the behemoths an enticing subject, scientists explain in the new documentary Black Holes: The Edge of All We Know .
When big discoveries happen, the camera is right there — allowing us to thrill in the moment when Event Horizon Telescope scientists first lay eyes on a black hole's visage. And we triumph as the team unveils the result in 2019, a now-familiar orange, ring-shaped image depicting the supermassive black hole in the center of galaxy M87 ( SN: 4/10/19 ). Likewise, scenes where Hawking questions his collaborators as they explain chalkboards full of equations prove mesmerizing.
And here's another article:
Cygnus X-1: The black hole that started it all | Astronomy.com
Black holes are a tricky bunch. While Einstein’s theory of relativity predicts they’re common, tracking down the first one was quite a challenge. Unlike stars, black holes themselves don’t emit any light, so the only thing we can measure about them is their size and spin.
There was little doubt in Hawking’s mind that black holes existed. After all, they were one of the focuses of his career. But whether scientists could actually find one was another question entirely.
Could a human enter a black hole to study it? | Astronomy.com
Triple star recipe for supersized stellar-mass black holes | Astronomy.com
This formidable and growing sample contains events in which one or both pre-merger black holes are so massive that they challenge standard theoretical models. A collapsing star should not be able to produce a black hole between about 50 and 130 solar masses, yet several detected black holes come very close or even surpass the lower limit of this so-called mass gap.
And in a paper published January 21 in The Astrophysical Journal Letters , a team of scientists proposed that triple stars could solve this conundrum.
One of the Milky Way's Biggest Black Holes Hid a Surprise - The Atlantic
There's a spot in space, thousands of light-years from here, that might best be described as a cosmic amusement park. A supergiant star, so hot that it glows electric blue, and a black hole spin around each other at extraordinary speeds, orbiting so closely that some of the star's material is pulled toward the black hole. The stellar particles swirl around the invisible object in a tilt-a-whirl of luminous reds and oranges.
Astronomers have studied this distant environment, and particularly the black hole, for decades. In fact, the black hole is the first ever discovered, after some years of research led to the breathtaking realization that this weird object couldn't be anything but an invisible pit of inscrutable depths.
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