In astronomy, the term black hole refers to a region in space where the gravitational pull is so intense that nothing, not even light, can escape its grasp. These enigmatic entities can be billions of times more massive than our Sun and are believed to reside at the centers of most galaxies, including our own Milky Way. Supermassive black holes exert such powerful influence that their activity can ripple throughout their host galaxies.
Recently, an international team led by researchers at MIT’s Haystack Observatory achieved a significant milestone by measuring the radius of a black hole in a distant galaxy for the first time. This measurement indicates the closest distance at which matter can approach before being irretrievably pulled into the black hole. To accomplish this, the scientists utilized a network of radio dishes across Hawaii, Arizona, and California, forming the Event Horizon Telescope (EHT). This unique telescope array is capable of resolving details 2,000 times finer than those visible with the Hubble Space Telescope.
The EHT focused on M87, a galaxy approximately 50 million light-years away from Earth, which harbors a black hole estimated to be 6 billion times more massive than our Sun. The team observed the glow of matter near the edge of this black hole, known as the event horizon. Shep Doeleman, assistant director at MIT Haystack Observatory, emphasized the significance of this boundary: “Once objects fall through the event horizon, they’re lost forever. It’s an exit door from our universe.”
Key Measurements
The EHT’s observations revealed that the diameter of M87*’s event horizon is about 40 billion kilometers, or roughly 270 astronomical units. This measurement is significant as it provides insights into the size and characteristics of black holes, which are among the most extreme objects predicted by Einstein’s theory of general relativity. The event horizon marks the boundary beyond which nothing can escape the gravitational pull of the black hole. Using advanced imaging techniques, researchers were able to observe the glow of matter near this boundary, confirming that more than 50% of the total flux at arcsecond scales originates from near the event horizon. The findings indicate that there is a dramatic suppression of emission within this region, consistent with theoretical predictions regarding black holes.
The findings from this research were published in Science, highlighting how supermassive black holes are among the most extreme objects predicted by Einstein’s theory of gravity. At their edges, gravitational forces are so strong that they draw in everything from their surroundings. However, not all matter crosses the event horizon; this leads to a “cosmic traffic jam,” where gas and dust accumulate into a flat structure known as an accretion disk. This disk orbits the black hole at nearly the speed of light, feeding it a continuous supply of superheated material and potentially causing it to spin in alignment with the orbiting matter.
Recent Developments
In October 2024, scientists captured the first image of a black hole using EHT observations of M87. This image reveals a bright ring formed by light bending around the intense gravitational field of the black hole, which is now measured to be 6.5 billion times more massive than our Sun. The imaging process involved advanced techniques such as Very Long Baseline Interferometry (VLBI), allowing for unprecedented resolution by linking telescopes across vast distances.
The EHT has continued to evolve since its initial observations in 2017. It now includes multiple telescopes and is set to observe Sagittarius A* (Sgr A*), the supermassive black hole at the center of our galaxy, again in April 2024. Each year brings improvements in imaging technology and data processing capabilities, enabling higher fidelity images and even potential movies capturing dynamic behavior around these black holes.
Implications
The ongoing research and imaging efforts surrounding black holes not only deepen our understanding of these cosmic giants but also enhance our knowledge of fundamental physics and cosmology. As astronomers refine their techniques and expand their observational capabilities, they continue to unlock mysteries about the nature of gravity and the evolution of galaxies throughout the universe.
Read More
[1] https://www.jpl.nasa.gov/edu/resources/teachable-moment/how-scientists-captured-the-first-image-of-a-black-hole/
[2] https://eventhorizontelescope.org/blog/astronomers-unveil-strong-magnetic-fields-spiraling-edge-milky-way%E2%80%99s-central-black-hole
[3] https://ui.adsabs.harvard.edu/abs/2019ApJ…875L…4E/abstract
[4] https://www.eso.org/public/science/EHT-MilkyWay/
[5] https://en.wikipedia.org/wiki/Event_Horizon_Telescope
[6] https://eventhorizontelescope.org/blog/astronomers-reveal-first-image-black-hole-heart-our-galaxy
8 comments
“Over time, this disk can cause the black hole to spin in the same direction as the orbiting material.”
That’s a chicken and egg problem. What came first, the black hole or the orbiting material?
It would seem that black holes must be rotating awfully fast before they can even attract any material. So the black hole (the chicken) must be first in this case…
Check out Nassim Haramein at
http://www.veoh.com/watch/v211655826NC94xJz?h1=Nassim+Haramein+-++Black+Whole+(2011
A black hole starts as a star, a chicken starts as an egg. All stars attract additional mass because they have mass. Mass attracts mass. Spin isn’t required to attract mass, afaik. Faster spin does not mean more gravity. More mass does. If a star has enough mass, nothing can escape its gravity, not even light.
There is no chicken and egg problem: The orbiting material orbits a pre-black hole star first.
We are material orbiting a star, of course, but our sun isn’t big enough to become a black hole… Even after it swells up and eats us.
The problem is, how does the mass concentrate to begin with. Obviously it won’t concentrate if there isn’t some kind of seed there. How did the star form, in other words. We are getting an idea that stars are formed at the center of a galaxy, in a way that somehow involves the action of the black hole that resides there.
Spin provides the seed for any accumulation of matter to form. It does that by providing a vortex, which tends to concentrate matter in one point. There is no star, no planet, no galaxy without that spin. We know now that all galaxies have a black hole at the center. We haven’t gotten around to find the black hole in stars and planets yet…
Mass concentrates without spin. Two completely still magnets still attract. I haven’t seen any evidence that spin is an attractive force. You get orbiting and spinning when any two randomly moving masses attract and “miss” hitting each other directly. The spin is a result of attraction, not the cause of it.
I suppose we will just have to disagree on that one.
In my book, spin is the basic force that will allow the formation of particles and of accumulations of particles which we see in star systems and galaxies.
Time will show…
In physics, things are often testable, so disagreements can become learning experiences. If spin is a force, I’d like to know about that. Thinking of macro scale forces and spin, do you agree that centrifugal force does not exist, but centripetal force does?
http://www.regentsprep.org/regents/physics/phys06/bcentrif/centrif.htm
Found something interesting in checking if I might be wrong: Is gravity a pseudo force caused by space time “spinning” in another dimension/inertial frame?
I don’t think spinning a mass or not increases or decreases its gravity, but is gravity itself the result of all mass wanting to continue in a “straight line” with reference to all other mass? You’d have to step out of this dimension to see the spin to which I’m referring.
A common misconception is that anything spinning has gravity due to its spin. If the earth was not spinning your weight might very slightly INCREASE, but it would not decrease. The gravity of a non-spinning earth would be the same. Spin does not create or change gravity… Unless the spinning causes you to eject mass. Mass causes gravity.
That’s a difficult one (centrifugal force). Had a long discussion some time back with an alt physics crowd. My takeaway was that centrifugal force is not a force but merely a result of inertia (the tendency to want to move in a straight line, rather than in a circle. Something that forces a circular movement “bends” the natural course of a mass which is straight or nearly so, and thereby gives rise to a counter-force which we call centrifugal, but which is really due to inertia.
I’m not saying we know what inertia exactly is, either. Neither do we know what causes gravity. This is all still in discussion and development. You won’t hear those questions in mainstream science as the tendency is to pretend we know it all already.
What we DO know and can demonstrate is that a vortex (which is a result of spin) has a tendency to concentrate, rather than disperse. You have seen depictions of a funnel that gets smaller and smaller at one end, and where the matter that’s being moved is rotating faster and faster the closer to the center point you get.
Gravity is usually associated with a mass (particles of matter) but the mechanism by which it works isn’t clear yet.
Accumulations of matter like a planet or a star exhibit gravity, but it wasn’t gravity that got them to exist in the first place. There is a missing link there, which in my view is the centripetal force of a space-time vortex, brought about by spin. You might ask what causes spin to create a space-time vortex. It is another one of those things that will have to wait for resolution until we know some more physics basics.